SCONS(1) SCons 4.9.1 SCONS(1)

NAME

scons - a software construction tool

SYNOPSIS

scons [options...] [name=val...] [targets...]

DESCRIPTION

SCons is an extensible open source build system that orchestrates the
construction of software (and other tangible products such as
documentation files) by determining which component pieces must be
built or rebuilt and invoking the necessary commands to build them.
SCons offers many features to improve developer productivity such as
parallel builds, caching of build artifacts, automatic dependency
scanning, and a database of information about previous builds so
details do not have to be recalculated each run.

scons requires Python 3.7 or later to run; there should be no other
dependencies or requirements, unless the experimental Ninja tool is
used (requires the ninja package).

Changed in version 4.3.0: support for Python 3.5 is removed. The
CPython project retired 3.5 in Sept 2020:
https://peps.python.org/pep-0478.

Changed in version 4.8.0: support for Python 3.6 is deprecated and
will be removed in a future SCons release. The CPython project
retired 3.6 in Sept 2021: https://peps.python.org/pep-0494.

Changed in version 4.9.0: support for Python 3.6 is removed.

You set up an SCons build by writing a script that describes things
to build (targets), and, if necessary, the rules to build those files
(actions). SCons comes with a collection of Builder methods which
supply premade Actions for building many common software components
such as executable programs, object files and libraries, so that for
many software projects, only the targets and input files (sources)
need be specified in a call to a builder.

SCons operates at a level of abstraction above that of pure
filenames. For example if you specify a shared library target named
"foo", SCons keeps track of the actual operating system dependent
filename (such as libfoo.so on a GNU/Linux system and foo.dll on
Windows), and gives you a handle to refer to that target in other
steps, so you don't have to use system-specific strings yourself.
SCons can also scan automatically for dependency information, such as
header files included by source code files (for example, #include
preprocessor directives in C or C++ files), so these implicit
dependencies do not have to be specified manually. SCons supports
the ability to define new scanners to support additional input file
types.

Information about files involved in the build, including a
cryptographic hash of the contents of source files, is cached for
later reuse. By default, this hash (the content signature) is used to
decide if a file has changed since the last build, although other
algorithms can be used by selecting an appropriate Decider function.
Implicit dependency files are also part of out-of-date computation.
The scanned implicit dependency information can optionally be cached
and used to speed up future builds. A hash of each executed build
action (the build signature) is also cached, so that changes to build
instructions (changing flags, etc.) or to the build tools themselves
(e.g. a compiler upgrade) can also trigger a rebuild.

SCons supports separated source and build directories (also called
"out-of-tree builds") through the definition of variant directories
Using a separated build directory helps keep the source directory
clean of artifacts when doing searches, allows setting up differing
builds ("variants") without conflicts, and allows resetting the build
by just removing the build directory (note that SCons does have a
"clean" mode as well). See the VariantDir description for more
details.

When invoked, scons looks for a file describing the build
configuration in the current directory and reads that in. The file is
by default named SConstruct, although some variants of that, or a
developer-chosen name, are also accepted (see the section called
"SConscript Files"). If found, the current directory is set as the
project top directory. Certain command-line options specify alternate
places to look for SConstruct (see -C, -D, -u and -U), which will set
the project top directory to the path found. A path to the build
configuration can also be specified with the -f option, which leaves
the current directory as the project top directory.

The build configuration may be split into multiple files: the
SConstruct file can specify additional configuration files by calling
the SConscript function, and any file thus invoked may include
further files in the same way. By convention, these subsidiary files
are named SConscript, although any name may be used. As a result of
this naming convention, the term SConscript files is used to refer
generically to the complete set of configuration files for a project
(including the SConstruct file), regardless of the actual file names
or number of such files. A hierarchical build is not recursive - all
of the SConscript files are processed in a single pass so that scons
has a picture of the complete dependency tree when it begins
considering what needs building. Each SConscript file is processed in
a separate context so settings made in one script do not leak into
another; information can however be shared explicitly between
scripts.

Before reading the SConscript files, scons looks for a site directory
- a directory named site_scons is searched for in various system
directories and in the project top directory, or if the --site-dir
option is given, checks only for that directory. Found site
directories are prepended to the Python module search path
(sys.path), thus allowing modules in such directories to be imported
in the normal Python way in SConscript files. For each found site
directory, (1) if it contains a file site_init.py that file is
evaluated, and (2) if it contains a directory site_tools the path to
that directory is prepended to the default toolpath. See the
--site-dir and --no-site-dir options for details on default paths and
controlling the site directories.

SConscript files are written in the Python programming language. For
many tasks, the simple syntax can be understood from examples, so it
is normally not necessary to be a Python programmer to use SCons
effectively. SConscript files are executed in a context that makes
the facilities described in this manual page directly available (that
is, no need to import). Standard Python scripting capabilities such
as flow control, data manipulation, and imported Python modules are
available to use in more complicated build configurations. Other
Python files can be made a part of the build system, but they do not
automatically have the SCons context and need to import it if they
need access (described later).

SCons reads and executes all of the included SConscript files before
it begins building any targets. Progress messages show this behavior
(the state change lines - those beginning with the scons: tag - may
be suppressed using the -Q option):

$ scons foo.out
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cp foo.in foo.out
scons: done building targets.
$

To assure reproducible builds, SCons uses a restricted execution
environment for running external commands used to build targets,
rather than propagating the full environment in effect at the time
scons was called. This helps avoid problems like picking up
accidental or malicious settings, temporary debug values that are no
longer needed, or a developer having different settings than another
(or than the CI pipeline). Environment variables needed for the
proper operation of such commands must be set in the execution
environment explicitly, either by assigning the desired values, or by
picking those values individually or collectively out of environment
variables exposed by the Python os.environ dictionary (as external
program inputs they should be validated before use). The execution
environment for a given construction environment is its $ENV value. A
small number of environment variables are picked up automatically by
scons itself (see the section called "ENVIRONMENT").

In particular, if a compiler or other external command needed to
build a target file is not in scons' idea of a standard system
location, it will not be found at runtime unless you explicitly add
the location into the execution environment's PATH element. This is a
particular consideration on Windows platforms, where it is common for
a command to install into an app-specific location and depend on
setting PATH in order for them to be found, which does not
automatically work for SCons.

One example approach is to extract the entire PATH environment
variable and set that into the execution environment:

import os
env = Environment(ENV={'PATH': os.environ['PATH']})

Similarly, if the commands use specific external environment
variables that scons does not recognize, they can be propagated into
the execution environment:

import os

env = Environment(
ENV={
'PATH': os.environ['PATH'],
'MODULEPATH': os.environ['MODULEPATH'],
'PKG_CONFIG_PATH': os.environ['PKG_CONFIG_PATH'],
}
)

Or you can explicitly propagate the invoking user's complete external
environment:

import os
env = Environment(ENV=os.environ.copy())

This comes at the expense of making your build dependent on the
user's environment being set correctly, but it may be more convenient
for some configurations. It should not cause problems if done in a
build setup which tightly controls how the environment is set up
before invoking scons, as in many continuous integration setups.

Note

The above fragments are intended to illustrate a concept. It is
normally not a good idea to wipe out the entire default value of
the execution environment (env["ENV"]), as it may carry important
information for the execution of build commands.

scons is normally executed in a top-level directory containing an
SConstruct file (the project top directory). When scons is invoked,
the command line (including the contents of the SCONSFLAGS
environment variable, if set) is processed. Command-line options (see
the section called "OPTIONS") are consumed. Any variable argument
assignments are collected, and remaining arguments are taken as
targets to build.

Values of variables to be passed to the SConscript files may be
specified on the command line:

scons debug=1

These variables are available through the ARGUMENTS dictionary, and
can be used in the SConscript files to modify the build in any way:

if ARGUMENTS.get("debug", ""):
env = Environment(CCFLAGS="-g")
else:
env = Environment()

The command-line variable arguments are also available in the ARGLIST
list, indexed by their order on the command line. This allows you to
process them in order rather than by name, if necessary. Each ARGLIST
entry is a tuple consisting of the name and the value.

See the section called "Command-Line Construction Variables" for more
information.

scons can maintain a cache of target (derived) files that can be
shared between multiple builds. When derived-file caching is enabled
in an SConscript file, any target files built by scons will be copied
to the cache. If an up-to-date target file is found in the cache, it
will be retrieved from the cache instead of being rebuilt locally.
Caching behavior may be disabled and controlled in other ways by the
--cache-force, --cache-disable, --cache-readonly, and --cache-show
command-line options. The --random option is useful to prevent
multiple builds from trying to update the cache simultaneously.

By default, scons searches for known programming tools on various
systems and initializes itself based on what is found. On Windows
systems which identify as win32, scons searches in order for the
Microsoft Visual C++ tools, the MinGW tool chain, the Intel compiler
tools, the GCC tools, the LLVM/clang tools, and the PharLap ETS
compiler. On Windows system which identify as cygwin (that is, if
scons is invoked from a cygwin shell), the order changes to prefer
the GCC toolchain over the MSVC tools. On OS/2 systems, scons
searches in order for the OS/2 compiler, the GCC tool chain, and the
Microsoft Visual C++ tools, On SGI IRIX, IBM AIX, Hewlett Packard
HP-UX, and Oracle Solaris systems, scons searches for the native
compiler tools (MIPSpro, Visual Age, aCC, and Forte tools
respectively) and the GCC tool chain. On all other platforms,
including POSIX (Linux and UNIX) and macOS platforms, scons searches
in order for the GCC tool chain, the LLVM/clang tools, and the Intel
compiler tools. The default tool selection can be pre-empted through
the use of the tools argument to construction environment creation
methods, explicitly calling the Tool loader, the through the setting
of various setting of construction variables.

Target Selection

SCons acts on the selected targets, whether the requested operation
is build, no-exec or clean. Targets are selected as follows:

1. Targets specified on the command line. These may be files,
directories, or phony targets defined using the Alias function.
Directory targets are scanned by scons for any targets that may
be found with a destination in or under that directory. The
targets listed on the command line are made available in the
COMMAND_LINE_TARGETS list.

2. If no targets are specified on the command line, scons will
select those targets specified in the SConscript files via calls
to the Default function. These are known as the default targets,
and are made available in the DEFAULT_TARGETS list.

3. If no targets are selected by the previous steps, scons selects
the current directory for scanning, unless command-line options
which affect the directory for target scanning are present (-C,
-D, -u, -U). Since targets thus selected were not the result of
user instructions, this target list is not made available for
direct inspection; use the --debug=explain option if they need to
be examined.

4. scons always adds to the selected targets any intermediate
targets which are necessary to build the specified ones. For
example, if constructing a shared library or dll from C source
files, scons will also build the object files which will make up
the library.

To ignore the default targets specified through calls to Default and
instead build all target files in or below the current directory
specify the current directory (.) as a command-line target:

scons .

To build all target files, including any files outside of the current
directory, supply a command-line target of the root directory (on
POSIX systems):

scons /

or the path name(s) of the volume(s) in which all the targets should
be built (on Windows systems):

scons C:\ D:\

A subset of a hierarchical tree may be built by remaining at the
project top directory and specifying the subdirectory as the target
to build:

scons src/subdir

or by changing directory and invoking scons with the -u option, which
traverses up the directory hierarchy until it finds the SConstruct
file, and then builds targets relatively to the current subdirectory
(see also the related -D and -U options):

cd src/subdir
scons -u .

In all cases, more files may be built than are requested, as scons
needs to make sure any dependent files are built.

Specifying "cleanup" targets in SConscript files is usually not
necessary. The -c flag removes all selected targets:

scons -c .

to remove all target files in or under the current directory, or:

scons -c build export

to remove target files under build and export.

Additional files or directories to remove can be specified using the
Clean function in the SConscript files. Conversely, targets that
would normally be removed by the -c invocation can be retained by
calling the NoClean function with those targets.

scons supports building multiple targets in parallel via a -j option
that takes, as its argument, the number of simultaneous tasks that
may be spawned:

scons -j 4

builds four targets in parallel, for example.

OPTIONS

In general, scons supports the same command-line options as GNU Make
and many of those supported by cons.

-b
Ignored for compatibility with non-GNU versions of Make

-c, --clean, --remove
Set clean mode. Clean up by removing the selected targets, well
as any files or directories associated with a selected target
through calls to the Clean function. Will not remove any targets
which are marked for preservation through calls to the NoClean
function.

While clean mode removes targets rather than building them, work
which is done directly in Python code in SConscript files will
still be carried out. If it is important to avoid some such work
from taking place in clean mode, it should be protected. An
SConscript file can determine which mode is active by querying
GetOption, as in the call if GetOption("clean"):

--cache-debug=file
Write debug information about derived-file caching to the
specified file. If file is a hyphen (-), the debug information is
printed to the standard output. The printed messages describe
what signature-file names are being looked for in, retrieved
from, or written to the derived-file cache specified by CacheDir.

--cache-disable, --no-cache
Disable derived-file caching. scons will neither retrieve files
from the cache nor copy files to the cache. This option can be
used to temporarily disable the cache without modifying the build
scripts.

--cache-force, --cache-populate
When using CacheDir, populate a derived-file cache by copying any
already-existing, up-to-date derived files to the cache, in
addition to files built by this invocation. This is useful to
populate a new cache with all the current derived files, or to
add to the cache any derived files recently built with caching
disabled via the --cache-disable option.

--cache-readonly
Use the derived-file cache, if enabled, to retrieve files, but do
not not update the cache with any files actually built during
this invocation.

--cache-show
When using a derived-file cache, show the command that would have
been executed to build the file (or the corresponding *COMSTR
contents if set) even if the file is retrieved from cache.
Without this option, scons shows a cache retrieval message if the
file is fetched from cache. This allows producing consistent
output for build logs, regardless of whether a target file was
rebuilt or retrieved from the cache.

--config=mode
Control how the Configure call should use or generate the results
of configuration tests. mode should be one of the following
choices:

auto
SCons will use its normal dependency mechanisms to decide if
a test must be rebuilt or not. This saves time by not running
the same configuration tests every time you invoke scons, but
will overlook changes in system header files or external
commands (such as compilers) if you don't specify those
dependencies explicitly. This is the default behavior.

force
If this mode is specified, all configuration tests will be
re-run regardless of whether the cached results are
out-of-date. This can be used to explicitly force the
configuration tests to be updated in response to an otherwise
unconfigured change in a system header file or compiler.

cache
If this mode is specified, no configuration tests will be
rerun and all results will be taken from cache. scons will
report an error if --config=cache is specified and a
necessary test does not have any results in the cache.


-C directory, --directory=directory
Run as if scons was started in directory instead of the current
working directory. That is, change directory before searching for
the SConstruct, Sconstruct, sconstruct, SConstruct.py,
Sconstruct.py or sconstruct.py file or doing anything else. When
multiple -C options are given, each subsequent non-absolute -C
directory is interpreted relative to the preceding one. See also
options -u, -U and -D to change the SConstruct search behavior
when this option is used.

-D
Works exactly the same way as the -u option except for the way
default targets are handled. When this option is used and no
targets are specified on the command line, all default targets
are built, whether or not they are below the current directory.

--debug=type[,type...]
Debug the build process. type specifies the kind of debugging
info to emit. Multiple types may be specified, separated by
commas. The following types are recognized:

action-timestamps
Prints additional time profiling information. For each
command, shows the absolute start and end times. This may be
useful in debugging parallel builds. Implies the --debug=time
option.

New in version 3.1.

count
Print how many objects are created of the various classes
used internally by SCons before and after reading the
SConscript files and before and after building targets. This
is not supported when SCons is executed with the Python -O
(optimized) option or when the SCons modules have been
compiled with optimization (that is, when executing from
*.pyo files).

duplicate
Print a line for each unlink/relink (or copy) of a file in a
variant directory from its source file. Includes debugging
info for unlinking stale variant directory files, as well as
unlinking old targets before building them.

explain
Print an explanation of why scons is deciding to (re-)build
the targets it selects for building.

findlibs
Instruct the scanner that searches for libraries to print a
message about each potential library name it is searching
for, and about the actual libraries it finds.

includes
Print the include tree after each top-level target is built.
This is generally used to find out what files are included by
the sources of a given derived file:

$ scons --debug=includes foo.o

json
Write info to a JSON file for any of the following debug
options if they are enabled: memory, count, time,
action-timestamps

The default output file is scons_stats.json

The file name/path can be modified by using DebugOptions for
example DebugOptions(json='path/to/file.json')

$ scons --debug=memory,json foo.o

memoizer
Prints a summary of hits and misses using the Memoizer, an
internal subsystem that counts how often SCons uses cached
values in memory instead of recomputing them each time
they're needed.

memory
Prints how much memory SCons uses before and after reading
the SConscript files and before and after building targets.

objects
Prints a list of the various objects of the various classes
used internally by SCons.

pdb
Run scons under control of the pdb Python debugger.

$ scons --debug=pdb
> /usr/lib/python3.11/site-packages/SCons/Script/Main.py(869)_main()
-> options = parser.values
(Pdb)

Note
pdb will stop at the beginning of the scons main routine
on startup. The search path (sys.path) at that point will
include the location of the running scons, but not of the
project itself. If you need to set breakpoints in your
project files, you will either need to add to the path,
or use absolute pathnames when referring to project
files. A .pdbrc file in the project root can be used to
add the current directory to the search path to avoid
having to enter it by hand, along these lines:

sys.path.append('.')

Due to the implementation of the pdb module, the break,
tbreak and clear commands only understand references to
filenames which have a .py extension. (although the
suffix itself can be omitted), except if you use an
absolute path. As a special exception to that rule, the
names SConstruct and SConscript are recognized without
needing the .py extension.


Changed in version 4.6.0: The names SConstruct and
SConscript are now recognized without requiring .py
suffix.


Changed in version 4.8.0: The name SCsub is now
recognized without requiring .py suffix.

prepare
Print a line each time any target (internal or external) is
prepared for building. scons prints this for each target it
considers, even if that target is up-to-date (see also
--debug=explain). This can help debug problems with targets
that aren't being built; it shows whether scons is at least
considering them or not.

presub
Print the raw command line used to build each target before
the construction environment variables are substituted. Also
shows which targets are being built by this command. Output
looks something like this:

$ scons --debug=presub
Building myprog.o with action(s):
$SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
...

stacktrace
Prints an internal Python stack trace when encountering an
otherwise unexplained error.

time
Prints various time profiling information:

+o The time spent executing each individual build command

+o The total build time (time SCons ran from beginning to
end)

+o The total time spent reading and executing SConscript
files

+o The total time SCons itself spent running (that is, not
counting reading and executing SConscript files)

+o The total time spent executing all build commands

+o The elapsed wall-clock time spent executing those build
commands

+o The time spent processing each file passed to the
SConscript function

(When scons is executed without the -j option, the elapsed
wall-clock time will typically be slightly longer than the
total time spent executing all the build commands, due to the
SCons processing that takes place in between executing each
command. When scons is executed with the -j option, and your
build configuration allows good parallelization, the elapsed
wall-clock time should be significantly smaller than the
total time spent executing all the build commands, since
multiple build commands and intervening SCons processing
should take place in parallel.)

sconscript
Enables output indicating entering and exiting each
SConscript file.


--diskcheck=type
Enable specific checks for whether or not there is a file on disk
where the SCons configuration expects a directory (or vice versa)
when searching for source and include files. type can be an
available diskcheck type or the special tokens all or none. A
comma-separated string can be used to select multiple checks. The
default setting is all.

Current available checks are:

match
to check that files and directories on disk match SCons'
expected configuration.

Disabling some or all of these checks can provide a performance
boost for large configurations, or when the configuration will
check for files and/or directories across networked or shared
file systems, at the slight increased risk of an incorrect build
or of not handling errors gracefully.

--duplicate=ORDER
There are three ways to duplicate files in a build tree: hard
links, soft (symbolic) links and copies. The default policy is to
prefer hard links to soft links to copies. You can specify a
different policy with this option. ORDER must be one of
hard-soft-copy (the default), soft-hard-copy, hard-copy,
soft-copy or copy. SCons will attempt to duplicate files using
the mechanisms in the specified order.

--enable-virtualenv
Import virtualenv-related variables to SCons.

--experimental=feature
Enable experimental features and/or tools. feature can be an
available feature name or the special tokens all or none. A
comma-separated string can be used to select multiple features.
The default setting is none.

Current available features are: ninja (New in version 4.2),
legacy_sched (New in version 4.6.0).

Caution
No Support offered for any features or tools enabled by this
flag.
New in version 4.2 (experimental).

-f file, --file=file, --makefile=file, --sconstruct=file
Use file as the initial SConscript file. Multiple -f options may
be specified, in which case scons will read all of the specified
files.

-h, --help
Print a local help message for this project, if one is defined in
the SConscript files (see the Help function), plus a line that
refers to the standard SCons help message. If no local help
message is defined, prints the standard SCons help message (as
for the -H option) plus help for any local options defined
through AddOption. Exits after displaying the appropriate
message.

Note that use of this option requires SCons to process the
SConscript files, so syntax errors may cause the help message not
to be displayed.

--hash-chunksize=KILOBYTES
Set the block size used when computing content signatures to
KILOBYTES. This value determines the size of the chunks which are
read in at once when computing signature hashes. Files below that
size are fully stored in memory before performing the signature
computation while bigger files are read in block-by-block. A huge
block-size leads to high memory consumption while a very small
block-size slows down the build considerably.

The default value is to use a chunk size of 64 kilobytes, which
should be appropriate for most uses.

New in version 4.1.

--hash-format=ALGORITHM
Set the hashing algorithm used by SCons to ALGORITHM. This value
determines the hashing algorithm used in generating content
signatures, build signatures and CacheDir keys.

The supported list of values are: md5, sha1 and sha256. However,
the Python interpreter used to run scons must have the
corresponding support available in the hashlib module to use the
specified algorithm.

If this option is omitted, the first supported hash format found
is selected. Typically, this is MD5, however, on a FIPS-compliant
system using a version of Python older than 3.9, SHA1 or SHA256
is chosen as the default. Python 3.9 and onwards clients always
default to MD5, even in FIPS mode.

Specifying this option changes the name of the SConsign database.
The default database is .sconsign.dblite. In the presence of this
option, ALGORITHM is included in the name to indicate the
difference, even if the argument is md5. For example,
--hash-format=sha256 uses a SConsign database named
.sconsign_sha256.dblite.

New in version 4.1.

-H, --help-options
Print the standard help message about SCons command-line options
and exit.

-i, --ignore-errors
Ignore all errors from commands executed to rebuild files.

-I directory, --include-dir=directory
Specifies a directory to search for imported Python modules. If
several -I options are used, the directories are searched in the
order specified.

--ignore-virtualenv
Suppress importing virtualenv-related variables to SCons.

--implicit-cache
Cache implicit dependencies. This causes scons to use the
implicit (scanned) dependencies from the last time it was run
instead of scanning the files for implicit dependencies. This can
significantly speed up SCons, but with the following limitations:

scons will not detect changes to implicit dependency search paths
(e.g. $CPPPATH, $LIBPATH) that would ordinarily cause different
versions of same-named files to be used.

scons will miss changes in the implicit dependencies in cases
where a new implicit dependency is added earlier in the implicit
dependency search path (e.g. $CPPPATH, $LIBPATH) than a current
implicit dependency with the same name.

--implicit-deps-changed
Forces SCons to ignore the cached implicit dependencies. This
causes the implicit dependencies to be rescanned and recached.
This implies --implicit-cache.

--implicit-deps-unchanged
Force SCons to ignore changes in the implicit dependencies. This
causes cached implicit dependencies to always be used. This
implies --implicit-cache.

--install-sandbox=sandbox_path
When using the Install builders, prepend sandbox_path to the
installation paths such that all installed files will be placed
under that directory. This option is unavailable if one of
Install, InstallAs or InstallVersionedLib is not used in the
SConscript files.

--interactive
Starts SCons in interactive mode. The SConscript files are read
once and a scons>>> prompt is printed. Targets may now be rebuilt
by typing commands at interactive prompt without having to
re-read the SConscript files and re-initialize the dependency
graph from scratch.

SCons interactive mode supports the following commands:

build [OPTIONS] [TARGETS] ...
Builds the specified TARGETS (and their dependencies) with
the specified SCons command-line OPTIONS. b and scons are
synonyms for build.

The following SCons command-line options affect the build
command:

--cache-debug=FILE
--cache-disable, --no-cache
--cache-force, --cache-populate
--cache-readonly
--cache-show
--debug=TYPE
-i, --ignore-errors
-j N, --jobs=N
-k, --keep-going
-n, --no-exec, --just-print, --dry-run, --recon
-Q
-s, --silent, --quiet
--taskmastertrace=FILE
--tree=OPTIONS

Any other SCons command-line options that are specified do
not cause errors but have no effect on the build command
(mainly because they affect how the SConscript files are
read, which only happens once at the beginning of interactive
mode).

clean [OPTIONS] [TARGETS] ...
Cleans the specified TARGETS (and their dependencies) with
the specified OPTIONS. c is a synonym. This command is
itself a synonym for build --clean

exit
Exits SCons interactive mode. You can also exit by
terminating input (Ctrl+D UNIX or Linux systems, (Ctrl+Z on
Windows systems).

help [COMMAND]
Provides a help message about the commands available in SCons
interactive mode. If COMMAND is specified, h and ? are
synonyms.

shell [COMMANDLINE]
Executes the specified COMMANDLINE in a subshell. If no
COMMANDLINE is specified, executes the interactive command
interpreter specified in the SHELL environment variable (on
UNIX and Linux systems) or the COMSPEC environment variable
(on Windows systems). sh and ! are synonyms.

version
Prints SCons version information.

An empty line repeats the last typed command. Command-line
editing can be used if the readline module is available.

$ scons --interactive
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons>>> build -n prog
scons>>> exit

-j N, --jobs=N
Specifies the maximum number of concurrent jobs (commands) to
run. If there is more than one -j option, the last one is
effective.

-k, --keep-going
Continue as much as possible after an error. The target that
failed and those that depend on it will not be remade, but other
targets specified on the command line will still be processed.

-m
Ignored for compatibility with non-GNU versions of Make.

--max-drift=SECONDS
Set the maximum expected drift in the modification time of files
to SECONDS. This value determines how long a file must be
unmodified before its cached content signature will be used
instead of calculating a new content signature (hash) of the
file's contents. The default value is 2 days, which means a file
must have a modification time of at least two days ago in order
to have its cached content signature used. A negative value means
to never cache the content signature and to ignore the cached
value if there already is one. A value of 0 means to always use
the cached signature, no matter how old the file is.

--md5-chunksize=KILOBYTES
A deprecated synonym for --hash-chunksize.

Changed in version 4.2: deprecated.

-n, --no-exec, --just-print, --dry-run, --recon
Set no-exec mode. Print the commands that would be executed to
build any out-of-date targets, but do not execute those commands.

Only target building is suppressed - any work in the build system
that is done directly (in regular Python code) will still be
carried out. You can add guards around code which should not be
executed in no-exec mode by checking the value of the option at
run time with GetOption:

if not GetOption("no_exec"):
# run regular instructions

The output is a best effort, as SCons cannot always precisely
determine what would be built. For example, if a file generated
by a builder action is also used as a source in the build, that
file is not available to scan for dependencies at all in an
unbuilt tree, and may contain out-of-date information in a
previously built tree.


SCons cannot perform Configure checks in no-exec mode, as they
would make changes to the filesystem (see $CONFIGUREDIR and
$CONFIGURELOG). It can use stored information from a previous
build, if it is not out-of-date, so a "priming" build may make
subsequent no-exec runs more useful.

--no-site-dir
Do not read site directories. Neither the standard site
directories (site_scons) nor the path specified via a previous
--site-dir option are added to the module search path sys.path,
searched for a site_init.py file, or have their site_tools
directory included in the tool search path. Can be overridden by
a subsequent --site-dir option.

--package-type=type
The type of package to create when using the Package builder.
Multiple types can be specified by using a comma-separated
string, in which case SCons will try to build for all of those
package types. Note this option is only available if the
packaging tool has been enabled.

--profile=file
Run SCons under the Python profiler and save the results to file.
The results may be analyzed using the Python pstats module.

-q, --question
Do not run any commands, or print anything. Just return an exit
status that is zero if the specified targets are already
up-to-date, non-zero otherwise.

-Q
Suppress status messages about reading SConscript files, building
targets and entering directories. Commands that are executed to
rebuild target files are still printed.

--random
Build dependencies in a random order. This is useful when
building multiple trees simultaneously with caching enabled, to
prevent multiple builds from simultaneously trying to build or
retrieve the same target files.

-s, --silent, --quiet
Silent. Do not print commands that are executed to rebuild target
files. Also suppresses SCons status messages.

-S, --no-keep-going, --stop
Ignored for compatibility with GNU Make

--site-dir=path
Use path as the site directory rather than searching the list of
default site directories. This directory will be prepended to
sys.path, the module path/site_init.py will be loaded if it
exists, and path/site_tools will be included in the tool search
path. The option is not additive - if given more than once, the
last path wins.

The default set of site directories searched when --site-dir is
not specified depends on the system platform, as follows. Users
or system administrators can tune site-specific or
project-specific SCons behavior by setting up a site directory in
one or more of these locations. Directories are examined in the
order given, from most generic ("system" directories) to most
specific (in the current project), so the last-executed
site_init.py file is the most specific one, giving it the chance
to override everything else), and the directories are prepended
to the paths, again so the last directory examined comes first in
the resulting path.

Windows:

%ALLUSERSPROFILE%/scons/site_scons
%LOCALAPPDATA%/scons/site_scons
%APPDATA%/scons/site_scons
%USERPROFILE%/.scons/site_scons
./site_scons

Note earlier versions of the documentation listed a different
path for the "system" site directory, this path is still
checked but its use is discouraged:

%ALLUSERSPROFILE%/Application Data/scons/site_scons

Mac OS X:

/Library/Application Support/SCons/site_scons
/opt/local/share/scons/site_scons (for MacPorts)
/sw/share/scons/site_scons (for Fink)
$HOME/Library/Application Support/SCons/site_scons
$HOME/.scons/site_scons
./site_scons

Solaris:

/opt/sfw/scons/site_scons
/usr/share/scons/site_scons
$HOME/.scons/site_scons
./site_scons

Linux, HPUX, and other Posix-like systems:

/usr/share/scons/site_scons
$HOME/.scons/site_scons
./site_scons

--stack-size=KILOBYTES
Set the size stack used to run threads to KILOBYTES. This value
determines the stack size of the threads used to run jobs. These
threads execute the actions of the builders for the nodes that
are out-of-date. This option has no effect unless the number of
concurrent build jobs is larger than one (as set by -j N or
--jobs=N on the command line or SetOption in a script).

Using a stack size that is too small may cause stack overflow
errors. This usually shows up as segmentation faults that cause
scons to abort before building anything. Using a stack size that
is too large will cause scons to use more memory than required
and may slow down the entire build process. The default value is
to use a stack size of 256 kilobytes, which should be appropriate
for most uses. You should not need to increase this value unless
you encounter stack overflow errors.

-t, --touch
Ignored for compatibility with GNU Make. (Touching a file to make
it appear up-to-date is unnecessary when using scons.)

--taskmastertrace=file
Prints trace information to the specified file about how the
internal Taskmaster object evaluates and controls the order in
which Nodes are built. A file name of - may be used to specify
the standard output.

--tree=type[,type...]
Prints a tree of the dependencies after each top-level target is
built. This prints out some or all of the tree, in various
formats, depending on the type specified:

all
Print the entire dependency tree after each top-level target
is built. This prints out the complete dependency tree,
including implicit dependencies and ignored dependencies.

derived
Restricts the tree output to only derived (target) files, not
source files.

linedraw
Draw the tree output using Unicode line-drawing characters
instead of plain ASCII text. This option acts as a modifier
to the selected type(s). If specified alone, without any
type, it behaves as if all had been specified.

New in version 4.0.

status
Prints status information for each displayed node.

prune
Prunes the tree to avoid repeating dependency information for
nodes that have already been displayed. Any node that has
already been displayed will have its name printed in [square
brackets], as an indication that the dependencies for that
node can be found by searching for the relevant output higher
up in the tree.

Multiple type choices may be specified, separated by commas:

# Prints only derived files, with status information:
scons --tree=derived,status

# Prints all dependencies of target, with status information
# and pruning dependencies of already-visited Nodes:
scons --tree=all,prune,status target

-u, --up, --search-up
Walks up the directory structure until an SConstruct, Sconstruct,
sconstruct, SConstruct.py, Sconstruct.py or sconstruct.py file is
found, and uses that as the project top directory. If no targets
are specified on the command line, only targets at or below the
current directory will be built.

-U
Works exactly the same way as the -u option except for the way
default targets are handled. When this option is used and no
targets are specified on the command line, all default targets
that are defined in the SConscript file(s) in the current
directory are built, regardless of what directory the resultant
targets end up in.

-v, --version
Print the scons version, copyright information, list of authors,
and any other relevant information. Then exit.

-w, --print-directory
Print a message containing the working directory before and after
other processing.

--no-print-directory
Turn off -w, even if it was turned on implicitly.

--warn=type, --warn=no-type
Enable or disable (with the prefix "no-") warnings (--warning is
a synonym). type specifies the type of warnings to be enabled or
disabled:

all
All warnings.

cache-version
Warnings about the derived-file cache directory specified by
CacheDir not using the latest configuration information.
These warnings are enabled by default.

cache-write-error
Warnings about errors trying to write a copy of a built file
to a specified derived-file cache specified by CacheDir.
These warnings are disabled by default.

cache-cleanup-error
Warnings about errors when a file retrieved from the
derived-file cache could not be removed.

corrupt-sconsign
Warnings about unfamiliar signature data in .sconsign files.
These warnings are enabled by default.

dependency
Warnings about dependencies. These warnings are disabled by
default.

deprecated
Warnings about use of currently deprecated features. These
warnings are enabled by default. Not all deprecation warnings
can be disabled with the --warn=no-deprecated option as some
deprecated features which are late in the deprecation cycle
may have been designated as mandatory warnings, and these
will still display. Warnings for certain deprecated features
may also be enabled or disabled individually; see below.

duplicate-environment
Warnings about attempts to specify a build of a target with
two different construction environments that use the same
action. These warnings are enabled by default.

fortran-cxx-mix
Warnings about linking Fortran and C++ object files in a
single executable, which can yield unpredictable behavior
with some compilers.

future-reserved-variable
Warnings about construction variables which are currently
allowed, but will become reserved variables in a future
release.

future-deprecated
Warnings about features that will be deprecated in the
future. Such warnings are disabled by default. Enabling
future deprecation warnings is recommended for projects that
redistribute SCons configurations for other users to build,
so that the project can be warned as soon as possible about
to-be-deprecated features that may require changes to the
configuration.

link
Warnings about link steps.

misleading-keywords
Warnings about the use of two commonly misspelled keywords
targets and sources to Builder calls. The correct spelling is
the singular form, even though target and source can
themselves refer to lists of names or nodes.

tool-qt-deprecated
Warnings about the qt tool being deprecated. These warnings
are disabled by default for the first phase of deprecation.
Enable to be reminded about use of this tool module. New in
version 4.3.

no-object-count
Warnings about the --debug=object feature not working when
scons is run with the Python -O option or from optimized
Python (.pyo) modules.

Note the "no-" prefix is part of the name of this warning.
Add another "-no" to disable.

no-parallel-support
Warnings about the version of Python not being able to
support parallel builds when the -j option is used. These
warnings are enabled by default.

Note the "no-" prefix is part of the name of this warning.
Add another "-no" to disable.

python-version
Warnings about running SCons using a version of Python that
has been deprecated. These warnings are enabled by default.

reserved-variable
Warnings about attempts to set the reserved construction
variable names $CHANGED_SOURCES, $CHANGED_TARGETS, $TARGET,
$TARGETS, $SOURCE, $SOURCES, $UNCHANGED_SOURCES or
$UNCHANGED_TARGETS. These warnings are disabled by default.

stack-size
Warnings about requests to set the stack size that could not
be honored. These warnings are enabled by default.

target-not-built
Warnings about a build rule not building the expected
targets. These warnings are disabled by default.


-Y repository, --repository=repository, --srcdir=repository
Search repository for any input and target files not found in the
local directory hierarchy. Multiple -Y options may be specified,
with repositories searched in the given order. See Repository for
more information.

SCONSCRIPT FILE REFERENCE

SConscript Files

The build configuration is described by one or more files, known as
SConscript files. There must be at least one file for a valid build
(scons will quit if it does not find one). scons by default looks
for this file by the name SConstruct in the directory from which you
run scons, though if necessary, also looks for alternative file names
Sconstruct, sconstruct, SConstruct.py, Sconstruct.py and
sconstruct.py in that order. A different file name (which can include
a pathname part) may be specified via the -f option. Except for the
SConstruct file, these files are not searched for automatically; you
add additional configuration files to the build by calling the
SConscript function. This allows parts of the build to be
conditionally included or excluded at run-time depending on how scons
is invoked.

Each SConscript file in a build configuration is invoked
independently in a separate context. This provides necessary
isolation so that different parts of the build don't accidentally
step on each other. You have to be explicit about sharing
information, by using the Export function or the exports argument to
the SConscript function, as well as the Return function in a called
SConscript file, and consume shared information by using the Import
function.

The following sections describe the various SCons facilities that can
be used in SConscript files. Quick links:
Construction Environments
Tools
Builder Methods
Functions and Environment Methods
SConscript Variables
Construction Variables
Configure Contexts
Command-Line Construction Variables
Node Objects

Construction Environments

A Construction Environment is the basic means by which you
communicate build information to SCons. A new construction
environment is created using the Environment function:

env = Environment()

Construction environment attributes called Construction Variables may
be set either by specifying them as keyword arguments when the object
is created or by assigning them a value after the object is created.
These two are nominally equivalent:

env = Environment(FOO='foo')
env['FOO'] = 'foo'

Note that certain settings which affect tool detection are referenced
only when the tools are initialized, so you need either to supply
them as part of the call to Environment, or defer tool
initialization. For example, initializing the Microsoft Visual C++
version you wish to use:

# initializes msvc to v14.1
env = Environment(MSVC_VERSION="14.1")

env = Environment()
# msvc tool was initialized to default, does not reinitialize
env['MSVC_VERSION'] = "14.1"

env = Environment(tools=[])
env['MSVC_VERSION'] = "14.1"
# msvc tool initialization was deferred, so will pick up new value
env.Tool('default')

As a convenience, construction variables may also be set or modified
by the parse_flags keyword argument during object creation, which has
the effect of the env.MergeFlags method being applied to the argument
value after all other processing is completed. This is useful either
if the exact content of the flags is unknown (for example, read from
a control file) or if the flags need to be distributed to a number of
construction variables. env.ParseFlags describes how these arguments
are distributed to construction variables.

env = Environment(parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable,
'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

An existing construction environment can be duplicated by calling the
env.Clone method. Without arguments, it will be a copy with the same
settings. Otherwise, env.Clone takes the same arguments as
Environment, and uses the arguments to create a modified copy.

SCons provides a special construction environment called the Default
Environment. The default environment is used only for global
functions, that is, construction activities called without the
context of a regular construction environment. See DefaultEnvironment
for more information.

By default, a new construction environment is initialized with a set
of builder methods and construction variables that are appropriate
for the current platform. The optional platform keyword argument may
be used to specify that the construction environment should be
initialized for a different platform:

env = Environment(platform='cygwin')

Specifying a platform initializes the appropriate construction
variables in the environment to use and generate file names with
prefixes and suffixes appropriate for that platform.

Note that the win32 platform adds the SystemDrive and SystemRoot
variables from the user's external environment to the construction
environment's ENV dictionary. This is so that any executed commands
that use sockets to connect with other systems will work on Windows
systems.

The platform argument may be a string value representing one of the
pre-defined platforms (aix, cygwin, darwin, hpux, irix, os2, posix,
sunos or win32), or a callable platform object returned by a call to
Platform selecting a pre-defined platform, or it may be a
user-supplied callable, in which case the Environment method will
call it to update the new construction environment:

def my_platform(env):
env['VAR'] = 'xyzzy'

env = Environment(platform=my_platform)

Note that supplying a non-default platform or custom function for
initialization may bypass settings that should happen for the host
system and should be used with care. It is most useful in the case
where the platform is an alternative for the one that would be
auto-detected, such as platform="cygwin" on a system which would
otherwise identify as win32.

The optional tools and toolpath keyword arguments affect the way
tools available to the environment are initialized. See the section
called "Tools" for details.

The optional variables keyword argument allows passing a Variables
object which will be used in the initialization of the construction
environment See the section called "Command-Line Construction
Variables" for details.

Tools

SCons has many included tool modules (more properly, tool
specification modules) which are used to help initialize the
construction environment prior to building, and more can be written
to suit a particular purpose, or added from external sources (a
repository of contributed tools is available). More information on
writing custom tools can be found in the Extending SCons section and
specifically Tool Modules.

An SCons tool is only responsible for setup. For example, if an
SConscript file declares the need to construct an object file from a
C-language source file by calling the Object builder, then a tool
module representing an available C compiler needs to have run first,
to set up that builder and all the construction variables it needs in
the associated construction environment. The tool itself is not
called in the process of the build. Tool setup happens when a
construction environment is constructed, and in the basic case needs
no intervention - platform-specific lists of default tools are used
to examine the specific capabilities of that platform and configure
the environment, skipping those tools which are not applicable.

If necessary, a specific set of tools to initialize in an environment
during creation may be specified using the optional keyword argument
tools. tools must be a list, even if there are one (or zero) tools.
This is useful to override the defaults, to specify non-default
built-in tools, and to cause added tools to be called:

env = Environment(tools=['msvc', 'lex'])

The tools argument overrides the default tool list, it does not add
to it, so be sure to include all the tools you need. For example, if
you are building a c/c++ program, you must specify a tool for at
least a compiler and a linker, as in tools=['clang', 'link'].

If the tools argument is omitted, or if tools includes the reserved
name 'default', then SCons will auto-detect usable tools, using the
search path from the execution environment (that is,
env['ENV']['PATH']) for looking up any external programs, and the
platform name in effect to determine the default tools for that
platform. Note the contents of PATH from the external environment
os.environ is not used. Changing the PATH in the execution
environment after the construction environment is constructed will
not cause the tools to be re-detected.

Tools can also be directly called by using the Tool method (see
below).

SCons supports the following tool specifications out of the box:

386asm
Sets construction variables for the 386ASM assembler for the Phar
Lap ETS embedded operating system.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

aixc++
Sets construction variables for the IMB xlc / Visual Age C++
compiler.

Sets: $CXX, $CXXVERSION, $SHCXX, $SHOBJSUFFIX.

aixcc
Sets construction variables for the IBM xlc / Visual Age C
compiler.

Sets: $CC, $CCVERSION, $SHCC.

aixf77
Sets construction variables for the IBM Visual Age f77 Fortran
compiler.

Sets: $F77, $SHF77.

aixlink
Sets construction variables for the IBM Visual Age linker.

Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

applelink
Sets construction variables for the Apple linker (similar to the
GNU linker).

Sets: $APPLELINK_COMPATIBILITY_VERSION,
$APPLELINK_CURRENT_VERSION, $APPLELINK_NO_COMPATIBILITY_VERSION,
$APPLELINK_NO_CURRENT_VERSION, $FRAMEWORKPATHPREFIX,
$LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX, $LDMODULESUFFIX,
$LINKCOM, $SHLINKCOM, $SHLINKFLAGS,
$_APPLELINK_COMPATIBILITY_VERSION, $_APPLELINK_CURRENT_VERSION,
$_FRAMEWORKPATH, $_FRAMEWORKS.

Uses: $FRAMEWORKSFLAGS.

ar
Sets construction variables for the ar library archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $RANLIB,
$RANLIBCOM, $RANLIBFLAGS.

as
Sets construction variables for the as assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

bcc32
Sets construction variables for the bcc32 compiler.

Sets: $CC, $CCCOM, $CCFLAGS, $CFILESUFFIX, $CFLAGS,
$CPPDEFPREFIX, $CPPDEFSUFFIX, $INCPREFIX, $INCSUFFIX, $SHCC,
$SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHOBJSUFFIX.

Uses: $_CPPDEFFLAGS, $_CPPINCFLAGS.

cc
Sets construction variables for generic POSIX C compilers.

Sets: $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CFILESUFFIX, $CFLAGS,
$CPPDEFPREFIX, $CPPDEFSUFFIX, $FRAMEWORKPATH, $FRAMEWORKS,
$INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS,
$SHOBJSUFFIX.

Uses: $CCCOMSTR, $PLATFORM, $SHCCCOMSTR.

clang
Set construction variables for the Clang C compiler.

Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

clangxx
Set construction variables for the Clang C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX,
$STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME.

compilation_db
Sets up CompilationDatabase builder which generates a clang
tooling compatible compilation database.

Sets: $COMPILATIONDB_COMSTR, $COMPILATIONDB_PATH_FILTER,
$COMPILATIONDB_USE_ABSPATH.

cvf
Sets construction variables for the Compaq Visual Fortran
compiler.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANMODDIR,
$FORTRANMODDIRPREFIX, $FORTRANMODDIRSUFFIX, $FORTRANPPCOM,
$OBJSUFFIX, $SHFORTRANCOM, $SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANFLAGS, $SHFORTRANFLAGS, $_CPPDEFFLAGS,
$_FORTRANINCFLAGS, $_FORTRANMODFLAG.

cXX
Sets construction variables for generic POSIX C++ compilers.

Sets: $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM,
$CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJSUFFIX,
$SHCXX, $SHCXXCOM, $SHCXXFLAGS, $SHOBJSUFFIX.

Uses: $CXXCOMSTR, $SHCXXCOMSTR.

cyglink
Set construction variables for cygwin linker/loader.

Sets: $IMPLIBPREFIX, $IMPLIBSUFFIX, $LDMODULEVERSIONFLAGS,
$LINKFLAGS, $RPATHPREFIX, $RPATHSUFFIX, $SHLIBPREFIX,
$SHLIBSUFFIX, $SHLIBVERSIONFLAGS, $SHLINKCOM, $SHLINKFLAGS,
$_LDMODULEVERSIONFLAGS, $_SHLIBVERSIONFLAGS.

default
Sets construction variables for a default list of Tool modules.
Use default in the tools list to retain the original defaults,
since the tools parameter is treated as a literal statement of
the tools to be made available in that construction environment,
not an addition.

The list of tools selected by default is not static, but is
dependent both on the platform and on the software installed on
the platform. Some tools will not initialize if an underlying
command is not found, and some tools are selected from a list of
choices on a first-found basis. The finished tool list can be
examined by inspecting the $TOOLS construction variable in the
construction environment.

On all platforms, the tools from the following list are selected
if their respective conditions are met: filesystem;, wix, lex,
yacc, rpcgen, swig, jar, javac, javah, rmic, dvipdf, dvips, gs,
tex, latex, pdflatex, pdftex, tar, zip, textfile.

On Linux systems, the default tools list selects (first-found): a
C compiler from gcc, intelc, icc, cc; a C++ compiler from g++,
intelc, icc, cXX; an assembler from gas, nasm, masm; a linker
from gnulink, ilink; a Fortran compiler from gfortran, g77,
ifort, ifl, f95, f90, f77; and a static archiver ar. It also
selects all found from the list m4 rpm.

On Windows systems, the default tools list selects (first-found):
a C compiler from msvc, mingw, gcc, intelc, icl, icc, cc, bcc32;
a C++ compiler from msvc, intelc, icc, g++, cXX, bcc32; an
assembler from masm, nasm, gas, 386asm; a linker from mslink,
gnulink, ilink, linkloc, ilink32; a Fortran compiler from
gfortran, g77, ifl, cvf, f95, f90, fortran; and a static archiver
from mslib, ar, tlib; It also selects all found from the list
msvs, midl.

On MacOS systems, the default tools list selects (first-found): a
C compiler from gcc, cc; a C++ compiler from g++, cXX; an
assembler as; a linker from applelink, gnulink; a Fortran
compiler from gfortran, f95, f90, g77; and a static archiver ar.
It also selects all found from the list m4, rpm.

Default lists for other platforms can be found by examining the
scons source code (see SCons/Tool/__init__.py).

dmd
Sets construction variables for D language compiler DMD.

Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
$DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
$DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
$DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX,
$DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX,
$DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX,
$DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC,
$SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM,
$SHDLINKFLAGS.

docbook
This tool tries to make working with Docbook in SCons a little
easier. It provides several toolchains for creating different
output formats, like HTML or PDF. Contained in the package is a
distribution of the Docbook XSL stylesheets as of version 1.76.1.
As long as you don't specify your own stylesheets for
customization, these official versions are picked as
default...which should reduce the inevitable setup hassles for
you.

Implicit dependencies to images and XIncludes are detected
automatically if you meet the HTML requirements. The additional
stylesheet utils/xmldepend.xsl by Paul DuBois is used for this
purpose.

Note, that there is no support for XML catalog resolving offered!
This tool calls the XSLT processors and PDF renderers with the
stylesheets you specified, that's it. The rest lies in your hands
and you still have to know what you're doing when resolving names
via a catalog.

For activating the tool "docbook", you have to add its name to
the Environment constructor, like this

env = Environment(tools=['docbook'])

On its startup, the docbook tool tries to find a required
xsltproc processor, and a PDF renderer, e.g. fop. So make sure
that these are added to your system's environment PATH and can be
called directly without specifying their full path.

For the most basic processing of Docbook to HTML, you need to
have installed

+o the Python lxml binding to libxml2, or

+o a standalone XSLT processor, currently detected are xsltproc,
saxon, saxon-xslt and xalan.

Rendering to PDF requires you to have one of the applications fop
or xep installed.

Creating a HTML or PDF document is very simple and
straightforward. Say

env = Environment(tools=['docbook'])
env.DocbookHtml('manual.html', 'manual.xml')
env.DocbookPdf('manual.pdf', 'manual.xml')

to get both outputs from your XML source manual.xml. As a
shortcut, you can give the stem of the filenames alone, like
this:

env = Environment(tools=['docbook'])
env.DocbookHtml('manual')
env.DocbookPdf('manual')

and get the same result. Target and source lists are also
supported:

env = Environment(tools=['docbook'])
env.DocbookHtml(['manual.html','reference.html'], ['manual.xml','reference.xml'])

or even

env = Environment(tools=['docbook'])
env.DocbookHtml(['manual','reference'])


Important
Whenever you leave out the list of sources, you may not
specify a file extension! The Tool uses the given names as
file stems, and adds the suffixes for target and source files
accordingly.
The rules given above are valid for the Builders DocbookHtml,
DocbookPdf, DocbookEpub, DocbookSlidesPdf and DocbookXInclude.
For the DocbookMan transformation you can specify a target name,
but the actual output names are automatically set from the
refname entries in your XML source.

The Builders DocbookHtmlChunked, DocbookHtmlhelp and
DocbookSlidesHtml are special, in that:

1. they create a large set of files, where the exact names and
their number depend on the content of the source file, and

2. the main target is always named index.html, i.e. the output
name for the XSL transformation is not picked up by the
stylesheets.

As a result, there is simply no use in specifying a target HTML
name. So the basic syntax for these builders is always:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual')

If you want to use a specific XSL file, you can set the
additional xsl parameter to your Builder call as follows:

env.DocbookHtml('other.html', 'manual.xml', xsl='html.xsl')

Since this may get tedious if you always use the same local
naming for your customized XSL files, e.g. html.xsl for HTML and
pdf.xsl for PDF output, a set of variables for setting the
default XSL name is provided. These are:

DOCBOOK_DEFAULT_XSL_HTML
DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
DOCBOOK_DEFAULT_XSL_HTMLHELP
DOCBOOK_DEFAULT_XSL_PDF
DOCBOOK_DEFAULT_XSL_EPUB
DOCBOOK_DEFAULT_XSL_MAN
DOCBOOK_DEFAULT_XSL_SLIDESPDF
DOCBOOK_DEFAULT_XSL_SLIDESHTML

and you can set them when constructing your environment:

env = Environment(
tools=['docbook'],
DOCBOOK_DEFAULT_XSL_HTML='html.xsl',
DOCBOOK_DEFAULT_XSL_PDF='pdf.xsl',
)
env.DocbookHtml('manual') # now uses html.xsl

Sets: $DOCBOOK_DEFAULT_XSL_EPUB, $DOCBOOK_DEFAULT_XSL_HTML,
$DOCBOOK_DEFAULT_XSL_HTMLCHUNKED, $DOCBOOK_DEFAULT_XSL_HTMLHELP,
$DOCBOOK_DEFAULT_XSL_MAN, $DOCBOOK_DEFAULT_XSL_PDF,
$DOCBOOK_DEFAULT_XSL_SLIDESHTML, $DOCBOOK_DEFAULT_XSL_SLIDESPDF,
$DOCBOOK_FOP, $DOCBOOK_FOPCOM, $DOCBOOK_FOPFLAGS,
$DOCBOOK_XMLLINT, $DOCBOOK_XMLLINTCOM, $DOCBOOK_XMLLINTFLAGS,
$DOCBOOK_XSLTPROC, $DOCBOOK_XSLTPROCCOM, $DOCBOOK_XSLTPROCFLAGS,
$DOCBOOK_XSLTPROCPARAMS.

Uses: $DOCBOOK_FOPCOMSTR, $DOCBOOK_XMLLINTCOMSTR,
$DOCBOOK_XSLTPROCCOMSTR.

dvi
Attaches the DVI builder to the construction environment.

dvipdf
Sets construction variables for the dvipdf utility.

Sets: $DVIPDF, $DVIPDFCOM, $DVIPDFFLAGS.

Uses: $DVIPDFCOMSTR.

dvips
Sets construction variables for the dvips utility.

Sets: $DVIPS, $DVIPSFLAGS, $PSCOM, $PSPREFIX, $PSSUFFIX.

Uses: $PSCOMSTR.

f03
Set construction variables for generic POSIX Fortran 03
compilers.

Sets: $F03, $F03COM, $F03FLAGS, $F03PPCOM, $SHF03, $SHF03COM,
$SHF03FLAGS, $SHF03PPCOM, $_F03INCFLAGS.

Uses: $F03COMSTR, $F03PPCOMSTR, $FORTRANCOMMONFLAGS,
$SHF03COMSTR, $SHF03PPCOMSTR.

f08
Set construction variables for generic POSIX Fortran 08
compilers.

Sets: $F08, $F08COM, $F08FLAGS, $F08PPCOM, $SHF08, $SHF08COM,
$SHF08FLAGS, $SHF08PPCOM, $_F08INCFLAGS.

Uses: $F08COMSTR, $F08PPCOMSTR, $FORTRANCOMMONFLAGS,
$SHF08COMSTR, $SHF08PPCOMSTR.

f77
Set construction variables for generic POSIX Fortran 77
compilers.

Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77FLAGS, $F77PPCOM,
$F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHF77,
$SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM,
$SHFORTRANFLAGS, $SHFORTRANPPCOM, $_F77INCFLAGS.

Uses: $F77COMSTR, $F77PPCOMSTR, $FORTRANCOMMONFLAGS,
$FORTRANCOMSTR, $FORTRANFLAGS, $FORTRANPPCOMSTR, $SHF77COMSTR,
$SHF77PPCOMSTR, $SHFORTRANCOMSTR, $SHFORTRANFLAGS,
$SHFORTRANPPCOMSTR.

f90
Set construction variables for generic POSIX Fortran 90
compilers.

Sets: $F90, $F90COM, $F90FLAGS, $F90PPCOM, $SHF90, $SHF90COM,
$SHF90FLAGS, $SHF90PPCOM, $_F90INCFLAGS.

Uses: $F90COMSTR, $F90PPCOMSTR, $FORTRANCOMMONFLAGS,
$SHF90COMSTR, $SHF90PPCOMSTR.

f95
Set construction variables for generic POSIX Fortran 95
compilers.

Sets: $F95, $F95COM, $F95FLAGS, $F95PPCOM, $SHF95, $SHF95COM,
$SHF95FLAGS, $SHF95PPCOM, $_F95INCFLAGS.

Uses: $F95COMSTR, $F95PPCOMSTR, $FORTRANCOMMONFLAGS,
$SHF95COMSTR, $SHF95PPCOMSTR.

fortran
Set construction variables for generic POSIX Fortran compilers.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHFORTRAN,
$SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANCOMSTR, $FORTRANPPCOMSTR,
$SHFORTRANCOMSTR, $SHFORTRANPPCOMSTR, $_CPPDEFFLAGS.

g++
Set construction variables for the g++ C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX.

g77
Set construction variables for the g77 Fortran compiler.

Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77PPCOM,
$F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHF77,
$SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM,
$SHFORTRANFLAGS, $SHFORTRANPPCOM.

Uses: $F77FLAGS, $FORTRANCOMMONFLAGS, $FORTRANFLAGS.

gas
Sets construction variables for the gas assembler. Calls the as
tool.

Sets: $AS.

gcc
Set construction variables for the gcc C compiler.

Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

gdc
Sets construction variables for the D language compiler GDC.

Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
$DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
$DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
$DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX,
$DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX,
$DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX,
$DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC,
$SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM,
$SHDLINKFLAGS.

gettext
A toolset supporting internationalization and localization of
software being constructed with SCons. The toolset loads the
following tools:


+o xgettext - extract internationalized messages from source
code to POT file(s).

+o msginit - initialize PO files during initial translation of
a project.

+o msgmerge - update PO files that already contain translated
messages,

+o msgfmt - compile textual PO files to binary installable MO
files.

When you enable gettext, it internally loads all the
above-mentioned tools, so you're encouraged to see their
individual documentation.

Each of the above tools provides its own builder(s) which may be
used to perform particular activities related to software
internationalization. You may be however interested in top-level
Translate builder.

To use the gettext tools, add the 'gettext' tool to your
construction environment:

env = Environment(tools=['default', 'gettext'])

gfortran
Sets construction variables for the GNU Fortran compiler. Calls
the fortran Tool module to set variables.

Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
$SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

gnulink
Set construction variables for GNU linker/loader.

Sets: $LDMODULEVERSIONFLAGS, $RPATHPREFIX, $RPATHSUFFIX,
$SHLIBVERSIONFLAGS, $SHLINKFLAGS, $_LDMODULESONAME,
$_SHLIBSONAME.

gs
This Tool sets the required construction variables for working
with the Ghostscript software. It also registers an appropriate
Action with the PDF Builder, such that the conversion from PS/EPS
to PDF happens automatically for the TeX/LaTeX toolchain.
Finally, it adds an explicit Gs Builder for Ghostscript to the
environment.

Sets: $GS, $GSCOM, $GSFLAGS.

Uses: $GSCOMSTR.

hpc++
Set construction variables for the compilers aCC on HP/UX
systems.

hpcc
Set construction variables for aCC compilers on HP/UX systems.
Calls the cXX tool for additional variables.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS.

hplink
Sets construction variables for the linker on HP/UX systems.

Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

icc
Sets construction variables for the icc compiler on OS/2 systems.

Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX.

Uses: $CCFLAGS, $CFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

icl
Sets construction variables for the Intel C/C++ compiler. Calls
the intelc Tool module to set its variables.

ifl
Sets construction variables for the Intel Fortran compiler.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHFORTRANCOM,
$SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANFLAGS, $_CPPDEFFLAGS, $_FORTRANINCFLAGS.

ifort
Sets construction variables for newer versions of the Intel
Fortran compiler for Linux.

Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
$SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

ilink
Sets construction variables for the ilink linker on OS/2 systems.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS.

ilink32
Sets construction variables for the Borland ilink32 linker.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS.

install
Sets construction variables for file and directory installation.

Sets: $INSTALL, $INSTALLSTR.

intelc
Sets construction variables for the Intel C/C++ compiler (Linux
and Windows, version 7 and later). Calls the gcc or msvc (on
Linux and Windows, respectively) tool to set underlying
variables.

Sets: $AR, $CC, $CXX, $INTEL_C_COMPILER_VERSION, $LINK.

jar
Sets construction variables for the jar utility.

Sets: $JAR, $JARCOM, $JARFLAGS, $JARSUFFIX.

Uses: $JARCOMSTR.

javac
Sets construction variables for the javac compiler.

Sets: $JAVABOOTCLASSPATH, $JAVAC, $JAVACCOM, $JAVACFLAGS,
$JAVACLASSPATH, $JAVACLASSSUFFIX, $JAVAINCLUDES, $JAVASOURCEPATH,
$JAVASUFFIX.

Uses: $JAVACCOMSTR.

javah
Sets construction variables for the javah tool.

Sets: $JAVACLASSSUFFIX, $JAVAH, $JAVAHCOM, $JAVAHFLAGS.

Uses: $JAVACLASSPATH, $JAVAHCOMSTR.

latex
Sets construction variables for the latex utility.

Sets: $LATEX, $LATEXCOM, $LATEXFLAGS.

Uses: $LATEXCOMSTR.

ldc
Sets construction variables for the D language compiler LDC2.

Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
$DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
$DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
$DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX,
$DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX,
$DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX,
$DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC,
$SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM,
$SHDLINKFLAGS.

lex
Sets construction variables for the lex lexical analyzer.

Sets: $LEX, $LEXCOM, $LEXFLAGS, $LEXUNISTD.

Uses: $LEXCOMSTR, $LEXFLAGS, $LEX_HEADER_FILE, $LEX_TABLES_FILE.

link
Sets construction variables for generic POSIX linkers. This is a
"smart" linker tool which selects a compiler to complete the
linking based on the types of source files.

Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS,
$LDMODULENOVERSIONSYMLINKS, $LDMODULEPREFIX, $LDMODULESUFFIX,
$LDMODULEVERSION, $LDMODULEVERSIONFLAGS, $LIBDIRPREFIX,
$LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM,
$LINKFLAGS, $SHLIBSUFFIX, $SHLINK, $SHLINKCOM, $SHLINKFLAGS,
$__LDMODULEVERSIONFLAGS, $__SHLIBVERSIONFLAGS.

Uses: $LDMODULECOMSTR, $LINKCOMSTR, $SHLINKCOMSTR.

linkloc
Sets construction variables for the LinkLoc linker for the Phar
Lap ETS embedded operating system.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $SHLINK, $SHLINKCOM,
$SHLINKFLAGS.

Uses: $LINKCOMSTR, $SHLINKCOMSTR.

m4
Sets construction variables for the m4 macro processor.

Sets: $M4, $M4COM, $M4FLAGS.

Uses: $M4COMSTR.

masm
Sets construction variables for the Microsoft assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $ASCOMSTR, $ASPPCOMSTR, $CPPFLAGS, $_CPPDEFFLAGS,
$_CPPINCFLAGS.

midl
Sets construction variables for the Microsoft IDL compiler.

Sets: $MIDL, $MIDLCOM, $MIDLFLAGS.

Uses: $MIDLCOMSTR.

mingw
Sets construction variables for MinGW (Minimal Gnu on Windows).

Sets: $AS, $CC, $CXX, $LDMODULECOM, $LIBPREFIX, $LIBSUFFIX,
$OBJSUFFIX, $RC, $RCCOM, $RCFLAGS, $RCINCFLAGS, $RCINCPREFIX,
$RCINCSUFFIX, $SHCCFLAGS, $SHCXXFLAGS, $SHLINKCOM, $SHLINKFLAGS,
$SHOBJSUFFIX, $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX.

Uses: $RCCOMSTR, $SHLINKCOMSTR.

msgfmt
This tool is a part of the gettext toolset. It provides SCons an
interface to the msgfmt(1) command by setting up the MOFiles
builder, which generates binary message catalog (MO) files from a
textual translation description (PO files).

Sets: $MOSUFFIX, $MSGFMT, $MSGFMTCOM, $MSGFMTCOMSTR,
$MSGFMTFLAGS, $POSUFFIX.

Uses: $LINGUAS_FILE.

msginit
This tool is a part of scons gettext toolset. It provides SCons
an interface to the msginit(1) program, by setting up the POInit
builder, which creates a new PO file, initializing the meta
information with values from the construction environment (or
options).

Sets: $MSGINIT, $MSGINITCOM, $MSGINITCOMSTR, $MSGINITFLAGS,
$POAUTOINIT, $POCREATE_ALIAS, $POSUFFIX, $POTSUFFIX,
$_MSGINITLOCALE.

Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

msgmerge
This tool is a part of scons gettext toolset. It provides SCons
an interface to the msgmerge(1) command, by setting up the
POUpdate builder, which merges two Uniform style .po files
together.

Sets: $MSGMERGE, $MSGMERGECOM, $MSGMERGECOMSTR, $MSGMERGEFLAGS,
$POSUFFIX, $POTSUFFIX, $POUPDATE_ALIAS.

Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

mslib
Sets construction variables for the Microsoft mslib library
archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

mslink
Sets construction variables for the Microsoft linker.

Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX,
$LDMODULESUFFIX, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $REGSVR, $REGSVRCOM,
$REGSVRFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS,
$WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX, $WINDOWSEXPPREFIX,
$WINDOWSEXPSUFFIX, $WINDOWSPROGMANIFESTPREFIX,
$WINDOWSPROGMANIFESTSUFFIX, $WINDOWSSHLIBMANIFESTPREFIX,
$WINDOWSSHLIBMANIFESTSUFFIX, $WINDOWS_INSERT_DEF.

Uses: $LDMODULECOMSTR, $LINKCOMSTR, $REGSVRCOMSTR, $SHLINKCOMSTR.

mssdk
Sets variables for Microsoft Platform SDK and/or Windows SDK.
Note that unlike most other Tool modules, mssdk does not set
construction variables, but sets the environment variables in the
environment SCons uses to execute the Microsoft toolchain:
%INCLUDE%, %LIB%, %LIBPATH% and %PATH%.

Uses: $MSSDK_DIR, $MSSDK_VERSION, $MSVS_VERSION.

msvc
Sets construction variables for the Microsoft Visual C++
compiler.

Sets: $BUILDERS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CCPCHFLAGS,
$CCPDBFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXX, $CXXCOM, $CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX,
$OBJPREFIX, $OBJSUFFIX, $PCHCOM, $PCHPDBFLAGS, $RC, $RCCOM,
$RCFLAGS, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHCXX,
$SHCXXCOM, $SHCXXFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

Uses: $CCCOMSTR, $CXXCOMSTR, $MSVC_NOTFOUND_POLICY,
$MSVC_SCRIPTERROR_POLICY, $MSVC_SCRIPT_ARGS, $MSVC_SDK_VERSION,
$MSVC_SPECTRE_LIBS, $MSVC_TOOLSET_VERSION, $MSVC_USE_SCRIPT,
$MSVC_USE_SCRIPT_ARGS, $MSVC_USE_SETTINGS, $MSVC_VERSION, $PCH,
$PCHSTOP, $PDB, $SHCCCOMSTR, $SHCXXCOMSTR.

msvs
Sets construction variables for Microsoft Visual Studio.

Sets: $MSVSBUILDCOM, $MSVSCLEANCOM, $MSVSENCODING,
$MSVSPROJECTCOM, $MSVSREBUILDCOM, $MSVSSCONS, $MSVSSCONSCOM,
$MSVSSCONSCRIPT, $MSVSSCONSFLAGS, $MSVSSOLUTIONCOM.

mwcc
Sets construction variables for the Metrowerks CodeWarrior
compiler.

Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXX, $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX,
$MWCW_VERSION, $MWCW_VERSIONS, $SHCC, $SHCCCOM, $SHCCFLAGS,
$SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS.

Uses: $CCCOMSTR, $CXXCOMSTR, $SHCCCOMSTR, $SHCXXCOMSTR.

mwld
Sets construction variables for the Metrowerks CodeWarrior
linker.

Sets: $AR, $ARCOM, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $SHLINK, $SHLINKCOM,
$SHLINKFLAGS.

nasm
Sets construction variables for the nasm Netwide Assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $ASCOMSTR, $ASPPCOMSTR.

ninja
Sets up the Ninja builder, which generates a ninja build file,
and then optionally runs ninja.

Note
This is an experimental feature. This functionality is
subject to change and/or removal without a deprecation cycle.
Sets: $IMPLICIT_COMMAND_DEPENDENCIES, $NINJA_ALIAS_NAME,
$NINJA_CMD_ARGS, $NINJA_COMPDB_EXPAND,
$NINJA_DEPFILE_PARSE_FORMAT, $NINJA_DIR, $NINJA_DISABLE_AUTO_RUN,
$NINJA_ENV_VAR_CACHE, $NINJA_FILE_NAME, $NINJA_FORCE_SCONS_BUILD,
$NINJA_GENERATED_SOURCE_ALIAS_NAME,
$NINJA_GENERATED_SOURCE_SUFFIXES, $NINJA_MSVC_DEPS_PREFIX,
$NINJA_POOL, $NINJA_REGENERATE_DEPS,
$NINJA_SCONS_DAEMON_KEEP_ALIVE, $NINJA_SCONS_DAEMON_PORT,
$NINJA_SYNTAX, $_NINJA_REGENERATE_DEPS_FUNC.

Uses: $AR, $ARCOM, $ARFLAGS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS,
$CXX, $CXXCOM, $ESCAPE, $LINK, $LINKCOM, $PLATFORM,
$PRINT_CMD_LINE_FUNC, $PROGSUFFIX, $RANLIB, $RANLIBCOM, $SHCCCOM,
$SHCXXCOM, $SHLINK, $SHLINKCOM.

packaging
Sets construction variables for the Package Builder. If this tool
is enabled, the --package-type command-line option is also
enabled.

pdf
Sets construction variables for the Portable Document Format
builder.

Sets: $PDFPREFIX, $PDFSUFFIX.

pdflatex
Sets construction variables for the pdflatex utility.

Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS.

Uses: $PDFLATEXCOMSTR.

pdftex
Sets construction variables for the pdftex utility.

Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS,
$PDFTEX, $PDFTEXCOM, $PDFTEXFLAGS.

Uses: $PDFLATEXCOMSTR, $PDFTEXCOMSTR.

python
Loads the Python source scanner into the invoking environment.
When loaded, the scanner will attempt to find implicit
dependencies for any Python source files in the list of sources
provided to an Action that uses this environment.

Available since scons 4.0..

qt
Placeholder tool to alert anyone still using qt tools to switch
to qt3 or newer tool.

qt3
Sets construction variables for building Qt3 applications.

Note
This tool is only suitable for building targeted to Qt3,
which is obsolete (the tool is deprecated since 4.3, and was
renamed to qt3 in 4.5.0. ). There are contributed tools for
Qt4 and Qt5, see https://github.com/SCons/scons-contrib[1].
Qt4 has also passed end of life for standard support (in Dec
2015).
Note paths for these construction variables are assembled using
the os.path.join method so they will have the appropriate
separator at runtime, but are listed here in the various entries
only with the '/' separator for simplicity.

In addition, the construction variables $CPPPATH, $LIBPATH and
$LIBS may be modified and the variables $PROGEMITTER,
$SHLIBEMITTER and $LIBEMITTER are modified. Because the
build-performance is affected when using this tool, you have to
explicitly specify it at Environment creation:

Environment(tools=['default','qt3'])

The qt3 tool supports the following operations:


Automatic moc file generation from header files. You do not have
to specify moc files explicitly, the tool does it for you.
However, there are a few preconditions to do so: Your header file
must have the same basename as your implementation file and must
stay in the same directory. It must have one of the suffixes .h,
.hpp, .H, .hxx, .hh. You can turn off automatic moc file
generation by setting $QT3_AUTOSCAN to False. See also the
corresponding Moc Builder.


Automatic moc file generation from C++ files. As described in the
Qt documentation, include the moc file at the end of the C++
file. Note that you have to include the file, which is generated
by the transformation
${QT3_MOCCXXPREFIX}<basename>${QT3_MOCCXXSUFFIX}, by default
<basename>.mo. A warning is generated after building the moc file
if you do not include the correct file. If you are using
VariantDir, you may need to specify duplicate=True. You can turn
off automatic moc file generation by setting $QT3_AUTOSCAN to
False. See also the corresponding Moc Builder.


Automatic handling of .ui files. The implementation files
generated from .ui files are handled much the same as yacc or lex
files. Each .ui file given as a source of Program, Library or
SharedLibrary will generate three files: the declaration file,
the implementation file and a moc file. Because there are also
generated headers, you may need to specify duplicate=True in
calls to VariantDir. See also the corresponding Uic Builder.

Sets: $QT3DIR, $QT3_AUTOSCAN, $QT3_BINPATH, $QT3_CPPPATH,
$QT3_LIB, $QT3_LIBPATH, $QT3_MOC, $QT3_MOCCXXPREFIX,
$QT3_MOCCXXSUFFIX, $QT3_MOCFROMCXXCOM, $QT3_MOCFROMCXXFLAGS,
$QT3_MOCFROMHCOM, $QT3_MOCFROMHFLAGS, $QT3_MOCHPREFIX,
$QT3_MOCHSUFFIX, $QT3_UIC, $QT3_UICCOM, $QT3_UICDECLFLAGS,
$QT3_UICDECLPREFIX, $QT3_UICDECLSUFFIX, $QT3_UICIMPLFLAGS,
$QT3_UICIMPLPREFIX, $QT3_UICIMPLSUFFIX, $QT3_UISUFFIX.

Uses: $QT3DIR.

rmic
Sets construction variables for the rmic utility.

Sets: $JAVACLASSSUFFIX, $RMIC, $RMICCOM, $RMICFLAGS.

Uses: $RMICCOMSTR.

rpcgen
Sets construction variables for building with RPCGEN.

Sets: $RPCGEN, $RPCGENCLIENTFLAGS, $RPCGENFLAGS,
$RPCGENHEADERFLAGS, $RPCGENSERVICEFLAGS, $RPCGENXDRFLAGS.

sgiar
Sets construction variables for the SGI library archiver.

Sets: $AR, $ARCOMSTR, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $SHLINK,
$SHLINKFLAGS.

Uses: $ARCOMSTR, $SHLINKCOMSTR.

sgic++
Sets construction variables for the SGI C++ compiler.

Sets: $CXX, $CXXFLAGS, $SHCXX, $SHOBJSUFFIX.

sgicc
Sets construction variables for the SGI C compiler.

Sets: $CXX, $SHOBJSUFFIX.

sgilink
Sets construction variables for the SGI linker.

Sets: $LINK, $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

sunar
Sets construction variables for the Sun library archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

sunc++
Sets construction variables for the Sun C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXX, $SHCXXFLAGS, $SHOBJPREFIX,
$SHOBJSUFFIX.

suncc
Sets construction variables for the Sun C compiler.

Sets: $CXX, $SHCCFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

sunf77
Set construction variables for the Sun f77 Fortran compiler.

Sets: $F77, $FORTRAN, $SHF77, $SHF77FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunf90
Set construction variables for the Sun f90 Fortran compiler.

Sets: $F90, $FORTRAN, $SHF90, $SHF90FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunf95
Set construction variables for the Sun f95 Fortran compiler.

Sets: $F95, $FORTRAN, $SHF95, $SHF95FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunlink
Sets construction variables for the Sun linker.

Sets: $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

swig
Sets construction variables for the SWIG interface compiler.

Sets: $SWIG, $SWIGCFILESUFFIX, $SWIGCOM, $SWIGCXXFILESUFFIX,
$SWIGDIRECTORSUFFIX, $SWIGFLAGS, $SWIGINCPREFIX, $SWIGINCSUFFIX,
$SWIGPATH, $SWIGVERSION, $_SWIGINCFLAGS.

Uses: $SWIGCOMSTR.

tar
Sets construction variables for the tar archiver.

Sets: $TAR, $TARCOM, $TARFLAGS, $TARSUFFIX.

Uses: $TARCOMSTR.

tex
Sets construction variables for the TeX formatter and typesetter.

Sets: $BIBTEX, $BIBTEXCOM, $BIBTEXFLAGS, $LATEX, $LATEXCOM,
$LATEXFLAGS, $MAKEINDEX, $MAKEINDEXCOM, $MAKEINDEXFLAGS, $TEX,
$TEXCOM, $TEXFLAGS.

Uses: $BIBTEXCOMSTR, $LATEXCOMSTR, $MAKEINDEXCOMSTR, $TEXCOMSTR.

textfile
Set construction variables for the Textfile and Substfile
builders.

Sets: $FILE_ENCODING, $LINESEPARATOR, $SUBSTFILEPREFIX,
$SUBSTFILESUFFIX, $TEXTFILEPREFIX, $TEXTFILESUFFIX.

Uses: $SUBST_DICT.

tlib
Sets construction variables for the Borland tlib library
archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

xgettext
This tool is a part of the gettext toolset. It provides SCons an
interface to the xgettext(1) program, which extracts
internationalized messages from source code. The tool sets up the
POTUpdate builder to make PO Template files.

Sets: $POTSUFFIX, $POTUPDATE_ALIAS, $XGETTEXTCOM,
$XGETTEXTCOMSTR, $XGETTEXTFLAGS, $XGETTEXTFROM,
$XGETTEXTFROMPREFIX, $XGETTEXTFROMSUFFIX, $XGETTEXTPATH,
$XGETTEXTPATHPREFIX, $XGETTEXTPATHSUFFIX, $_XGETTEXTDOMAIN,
$_XGETTEXTFROMFLAGS, $_XGETTEXTPATHFLAGS.

Uses: $POTDOMAIN.

yacc
Sets construction variables for the yacc parser generator.

Sets: $YACC, $YACCCOM, $YACCFLAGS, $YACCHFILESUFFIX,
$YACCHXXFILESUFFIX, $YACCVCGFILESUFFIX, $YACC_GRAPH_FILE_SUFFIX.

Uses: $YACCCOMSTR, $YACCFLAGS, $YACC_GRAPH_FILE,
$YACC_HEADER_FILE.

zip
Sets construction variables for the zip archiver.

Sets: $ZIP, $ZIPCOM, $ZIPCOMPRESSION, $ZIPFLAGS, $ZIPSUFFIX.

Uses: $ZIPCOMSTR.

Builder Methods

You tell SCons what to build by calling Builders, functions which
take particular action(s) to produce target(s) of a particular type
(conventionally hinted at by the builder name, e.g. Program) from
the specified source files. A builder call is a declaration: SCons
enters the specified relationship into its internal dependency node
graph, and only later makes the decision on whether anything is
actually built, since this depends on command-line options, target
selection rules, and whether the target(s) are out-of-date with
respect to the sources.

SCons provides a number of builders, and you can also write your own
(see Builder Objects). Builders are created dynamically at run-time,
often (though not always) by tools which determine whether the
external dependencies for the builder are satisfied, and which
perform the necessary setup (see Tools). Builders are attached to a
construction environment as methods. The available builder methods
are registered as key-value pairs in the $BUILDERS attribute of the
construction environment, so the available builders can be examined.
This example displays them for debugging purposes:

env = Environment()
print("Builders:", list(env['BUILDERS']))

Builder methods take two required arguments: target and source. The
target and source arguments can be specified either as positional
arguments, in which case target comes first, or as keyword arguments,
using target= and source=. Although both arguments are nominally
required, if there is a single source and the target can be inferred
the target argument can be omitted (see below). Builder methods also
take a variety of keyword arguments, described below.

Because long lists of file names can lead to a lot of quoting in a
builder call, SCons supplies a Split global function and a same-named
environment method that splits a single string into a list, using
strings of white-space characters as the delimiter (similar to the
Python string split method, but succeeds even if the input isn't a
string).

The following are equivalent examples of calling the Program builder
method:

env.Program('bar', ['bar.c', 'foo.c'])
env.Program('bar', Split('bar.c foo.c'))
env.Program('bar', env.Split('bar.c foo.c'))
env.Program(source=['bar.c', 'foo.c'], target='bar')
env.Program(target='bar', source=Split('bar.c foo.c'))
env.Program(target='bar', source=env.Split('bar.c foo.c'))
env.Program('bar', source='bar.c foo.c'.split())

Sources and targets can be specified as a scalar or as a list,
composed of either strings or nodes (more on nodes below). When
specifying path strings, Python follows the POSIX pathname
convention: if a string begins with the operating system pathname
separator (on Windows both the slash and backslash separator are
accepted, and any leading drive specifier is ignored for the
determination) it is considered an absolute path, otherwise it is a
relative path. If the path string contains no separator characters,
it is searched for as a file in the current directory. If it contains
separator characters, the search follows down from the starting
point, which is the top of the directory tree for an absolute path
and the current directory for a relative path. The "current
directory" in this context is the directory of the SConscript file
currently being processed.

SCons also recognizes a third way to specify path strings: if the
string begins with the # character it is top-relative - it works like
a relative path, but the search follows down from the project top
directory rather than from the current directory. The # can
optionally be followed by a pathname separator, which is ignored if
found in that position. Top-relative paths only work in places where
scons will interpret the path (see some examples below). To be used
in other contexts the string will need to be converted to a relative
or absolute path first.

Examples:

# The comments describing the targets that will be built
# assume these calls are in a SConscript file in the
# a subdirectory named "subdir".

# Builds the program "subdir/foo" from "subdir/foo.c":
env.Program('foo', 'foo.c')

# Builds the program "/tmp/bar" from "subdir/bar.c":
env.Program('/tmp/bar', 'bar.c')

# An initial '#' or '#/' are equivalent; the following
# calls build the programs "foo" and "bar" (in the
# top-level SConstruct directory) from "subdir/foo.c" and
# "subdir/bar.c", respectively:
env.Program('#foo', 'foo.c')
env.Program('#/bar', 'bar.c')

# Builds the program "other/foo" (relative to the top-level
# SConstruct directory) from "subdir/foo.c":
env.Program('#other/foo', 'foo.c')

# This will not work, only SCons interfaces understand '#',
# os.path.exists is pure Python:
if os.path.exists('#inc/foo.h'):
env.Append(CPPPATH='#inc')

When the target shares the same base name as the source and only the
suffix varies, and if the builder method has a suffix defined for the
target file type, then the target argument may be omitted completely,
and scons will deduce the target file name from the source file name.
The following examples all build the executable program bar (on POSIX
systems) or bar.exe (on Windows systems) from the bar.c source file:

env.Program(target='bar', source='bar.c')
env.Program('bar', source='bar.c')
env.Program(source='bar.c')
env.Program('bar.c')

The optional srcdir keyword argument specifies that all source file
strings that are not absolute paths or top-relative paths shall be
interpreted relative to the specified srcdir. The following example
will build the build/prog (or build/prog.exe on Windows) program from
the files src/f1.c and src/f2.c:

env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

The optional parse_flags keyword argument causes behavior similar to
the env.MergeFlags method, where the argument value is broken into
individual settings and merged into the appropriate construction
variables.

env.Program('hello', 'hello.c', parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable,
'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

The optional chdir keyword argument specifies that the Builder's
action(s) should be executed after changing directory. If the chdir
argument is a path string or a directory Node, scons will change to
the specified directory. If the chdir is not a string or Node and
evaluates true, then scons will change to the target file's
directory.

Warning

Python only keeps one current directory location even if there
are multiple threads. This means that use of the chdir argument
will not work with the SCons -j option, because individual worker
threads spawned by SCons interfere with each other when they
start changing directory.

# scons will change to the "sub" subdirectory
# before executing the "cp" command.
env.Command(
target='sub/dir/foo.out',
source='sub/dir/foo.in',
action="cp dir/foo.in dir/foo.out",
chdir='sub',
)

# Because chdir is not a string, scons will change to the
# target's directory ("sub/dir") before executing the
# "cp" command.
env.Command('sub/dir/foo.out', 'sub/dir/foo.in', "cp foo.in foo.out", chdir=True)

Note that SCons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the chdir
keyword argument--that is, the expanded file names will still be
relative to the project top directory, and consequently incorrect
relative to the chdir directory. If you use the chdir keyword
argument, you will typically need to supply a different command line
using expansions like ${TARGET.file} and ${SOURCE.file} to use just
the filename portion of the target and source.

Keyword arguments that are not specifically recognized are treated as
construction variable overrides, which replace or add those variables
on a limited basis. These overrides will only be in effect when
building the target of the builder call, and will not affect other
parts of the build. For example, if you want to specify some
libraries needed by just one program:

env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

or generate a shared library with a non-standard suffix:

env.SharedLibrary(
target='word',
source='word.cpp',
SHLIBSUFFIX='.ocx',
LIBSUFFIXES=['.ocx'],
)

Note that both the $SHLIBSUFFIX and $LIBSUFFIXES construction
variables must be set if you want scons to search automatically for
dependencies on the non-standard library names; see the descriptions
of these variables for more information.

Although the builder methods defined by scons are, in fact, methods
of a construction environment object, many may also be called without
an explicit environment:

Program('hello', 'hello.c')
SharedLibrary('word', 'word.cpp')

If called this way, the builder will internally use the Default
Environment that consists of the tools and values that scons has
determined are appropriate for the local system.

Builder methods that can be called without an explicit environment
(indicated in the listing of builders below without a leading env.)
may be called from custom Python modules that you import into an
SConscript file by adding the following to the Python module:

from SCons.Script import *

A builder may add additional targets beyond those requested if an
attached Emitter chooses to do so (see the section called "Builder
Objects" for more information. $PROGEMITTER is an example). For
example, the GNU linker takes a command-line argument -Map=mapfile,
which causes it to produce a linker map file in addition to the
executable file actually being linked. If the Program builder's
emitter is configured to add this mapfile if the option is set, then
two targets will be returned when you only provided for one.

For this reason, builder methods always return a NodeList, a
list-like object whose elements are Nodes. Nodes are the internal
representation of build targets or sources (see the section called
"Node Objects" for more information). The returned NodeList object
can be passed to other builder methods as source(s) or to other SCons
functions or methods where a path string would normally be accepted.

For example, to add a specific preprocessor define when compiling one
specific object file but not the others:

bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
env.Program("prog", ['foo.c', bar_obj_list, 'main.c'])

Using a Node as in this example makes for a more portable build by
avoiding having to specify a platform-specific object suffix when
calling the Program builder method.

The NodeList object is also convenient to pass to the Default
function, for the same reason of avoiding a platform-specific name:

tgt = env.Program("prog", ["foo.c", "bar.c", "main.c"])
Default(tgt)

Builder calls will automatically "flatten" lists passed as source and
target, so they are free to contain elements which are themselves
lists, such as bar_obj_list returned by the StaticObject call. If you
need to manipulate a list of lists returned by builders directly in
Python code, you can either build a new list by hand:

foo = Object('foo.c')
bar = Object('bar.c')
objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
for obj in objects:
print(str(obj))

Or you can use the Flatten function supplied by SCons to create a
list containing just the Nodes, which may be more convenient:

foo = Object('foo.c')
bar = Object('bar.c')
objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
for obj in objects:
print(str(obj))

Since builder calls return a list-like object, not an actual Python
list, it is not appropriate to use the Python add operator (+ or +=)
to append builder results to a Python list. Because the list and the
object are different types, Python will not update the original list
in place, but will instead create a new NodeList object containing
the concatenation of the list elements and the builder results. This
will cause problems for any other Python variables in your SCons
configuration that still hold on to a reference to the original list.
Instead, use the Python list extend method to make sure the list is
updated in-place. Example:

object_files = []

# Do NOT use += here:
# object_files += Object('bar.c')
#
# It will not update the object_files list in place.
#
# Instead, use the list extend method:
object_files.extend(Object('bar.c'))

The path name for a Node's file may be used by passing the Node to
Python's built-in str function:

bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
print("The path to bar_obj is:", str(bar_obj_list[0]))

Note that because the Builder call returns a NodeList, you have to
access the first element in the list (bar_obj_list[0] in the example)
to get at the Node that actually represents the object file.

When trying to handle errors that may occur in a builder method,
consider that the corresponding Action is executed at a different
time than the SConscript file statement calling the builder. It is
not useful to wrap a builder call in a try block, since success in
the builder call is not the same as the builder itself succeeding. If
necessary, a Builder's Action should be coded to exit with a useful
exception message indicating the problem in the SConscript files -
programmatically recovering from build errors is rarely useful.

The following builder methods are predefined in the SCons core
software distribution. Depending on the setup of a particular
construction environment and on the type and software installation
status of the underlying system, not all builders may be available in
that construction environment. Since the function calling signature
is the same for all builders:

Buildername(target, source, [key=val, ...])

it is omitted in this listing for brevity.

CFile(), env.CFile()
Builds a C source file given a lex (.l) or yacc (.y) input file.
The suffix specified by the $CFILESUFFIX construction variable
(.c by default) is automatically added to the target if it is not
already present. Example:

# builds foo.c
env.CFile(target='foo.c', source='foo.l')

# builds bar.c
env.CFile(target='bar', source='bar.y')

Command(), env.Command()
There is actually no Builder named Command, rather the term
"Command Builder" refers to a function which, on each call,
creates and calls an anonymous Builder. This is useful for
"one-off" builds where a full Builder is not needed. Since the
anonymous Builder is never hooked into the standard Builder
framework, an Action must always be specified. See the Command
function description for the calling syntax and details.

CompilationDatabase(), env.CompilationDatabase()

CompilationDatabase is a special builder which adds a target to
create a JSON formatted compilation database compatible with
clang tooling (see the LLVM specification[2]). This database is
suitable for consumption by various tools and editors who can use
it to obtain build and dependency information which otherwise
would be internal to SCons. The builder does not require any
source files to be specified, rather it arranges to emit
information about all of the C, C++ and assembler source/output
pairs identified in the build that are not excluded by the
optional filter $COMPILATIONDB_PATH_FILTER. The target is subject
to the usual SCons target selection rules.

If called with no arguments, the builder will default to a target
name of compile_commands.json.

If called with a single positional argument, scons will "deduce"
the target name from that source argument, giving it the same
name, and then ignore the source. This is the usual way to call
the builder if a non-default target name is wanted.

If called with either the target= or source= keyword arguments,
the value of the argument is taken as the target name. If called
with both, the target= value is used and source= is ignored. If
called with multiple sources, the source list will be ignored,
since there is no way to deduce what the intent was; in this case
the default target name will be used.

Note
You must load the compilation_db tool prior to specifying any
part of your build or some source/output files will not show
up in the compilation database.
Available since scons 4.0.

CXXFile(), env.CXXFile()
Builds a C++ source file given a lex (.ll) or yacc (.yy) input
file. The suffix specified by the $CXXFILESUFFIX construction
variable (.cc by default) is automatically added to the target if
it is not already present. Example:

# builds foo.cc
env.CXXFile(target='foo.cc', source='foo.ll')

# builds bar.cc
env.CXXFile(target='bar', source='bar.yy')

DocbookEpub(), env.DocbookEpub()
A pseudo-Builder, providing a Docbook toolchain for EPUB output.

env = Environment(tools=['docbook'])
env.DocbookEpub('manual.epub', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookEpub('manual')

DocbookHtml(), env.DocbookHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML output.

env = Environment(tools=['docbook'])
env.DocbookHtml('manual.html', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookHtml('manual')

DocbookHtmlChunked(), env.DocbookHtmlChunked()
A pseudo-Builder providing a Docbook toolchain for chunked HTML
output. It supports the base.dir parameter. The chunkfast.xsl
file (requires "EXSLT") is used as the default stylesheet. Basic
syntax:

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('manual')

where manual.xml is the input file.

If you use the root.filename parameter in your own stylesheets
you have to specify the new target name. This ensures that the
dependencies get correct, especially for the cleanup via "scons
-c":

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('mymanual.html', 'manual', xsl='htmlchunk.xsl')

Some basic support for the base.dir parameter is provided. You
can add the base_dir keyword to your Builder call, and the given
prefix gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('manual', xsl='htmlchunk.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookHtmlhelp(), env.DocbookHtmlhelp()
A pseudo-Builder, providing a Docbook toolchain for HTMLHELP
output. Its basic syntax is:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual')

where manual.xml is the input file.

If you use the root.filename parameter in your own stylesheets
you have to specify the new target name. This ensures that the
dependencies get correct, especially for the cleanup via "scons
-c":

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('mymanual.html', 'manual', xsl='htmlhelp.xsl')

Some basic support for the base.dir parameter is provided. You
can add the base_dir keyword to your Builder call, and the given
prefix gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual', xsl='htmlhelp.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookMan(), env.DocbookMan()
A pseudo-Builder, providing a Docbook toolchain for Man page
output. Its basic syntax is:

env = Environment(tools=['docbook'])
env.DocbookMan('manual')

where manual.xml is the input file. Note, that you can specify a
target name, but the actual output names are automatically set
from the refname entries in your XML source.

DocbookPdf(), env.DocbookPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF output.

env = Environment(tools=['docbook'])
env.DocbookPdf('manual.pdf', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookPdf('manual')

DocbookSlidesHtml(), env.DocbookSlidesHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML slides
output.

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('manual')

If you use the titlefoil.html parameter in your own stylesheets
you have to give the new target name. This ensures that the
dependencies get correct, especially for the cleanup via "scons
-c":

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('mymanual.html','manual', xsl='slideshtml.xsl')

Some basic support for the base.dir parameter is provided. You
can add the base_dir keyword to your Builder call, and the given
prefix gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('manual', xsl='slideshtml.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookSlidesPdf(), env.DocbookSlidesPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF slides
output.

env = Environment(tools=['docbook'])
env.DocbookSlidesPdf('manual.pdf', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookSlidesPdf('manual')

DocbookXInclude(), env.DocbookXInclude()
A pseudo-Builder, for resolving XIncludes in a separate
processing step.

env = Environment(tools=['docbook'])
env.DocbookXInclude('manual_xincluded.xml', 'manual.xml')

DocbookXslt(), env.DocbookXslt()
A pseudo-Builder, applying a given XSL transformation to the
input file.

env = Environment(tools=['docbook'])
env.DocbookXslt('manual_transformed.xml', 'manual.xml', xsl='transform.xslt')

Note, that this builder requires the xsl parameter to be set.

DVI(), env.DVI()
Builds a .dvi file from a .tex, .ltx or .latex input file. If the
source file suffix is .tex, scons will examine the contents of
the file; if the string \documentclass or \documentstyle is
found, the file is assumed to be a LaTeX file and the target is
built by invoking the $LATEXCOM command line; otherwise, the
$TEXCOM command line is used. If the file is a LaTeX file, the
DVI builder method will also examine the contents of the .aux
file and invoke the $BIBTEX command line if the string bibdata is
found, start $MAKEINDEX to generate an index if a .ind file is
found and will examine the contents .log file and re-run the
$LATEXCOM command if the log file says it is necessary.

The suffix .dvi (hard-coded within TeX itself) is automatically
added to the target if it is not already present. Examples:

# builds from aaa.tex
env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
# builds bbb.dvi
env.DVI(target = 'bbb', source = 'bbb.ltx')
# builds from ccc.latex
env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

Gs(), env.Gs()
A Builder for explicitly calling the gs executable. Depending on
the underlying OS, the different names gs, gsos2 and gswin32c are
tried.

env = Environment(tools=['gs'])
env.Gs(
'cover.jpg',
'scons-scons.pdf',
GSFLAGS='-dNOPAUSE -dBATCH -sDEVICE=jpeg -dFirstPage=1 -dLastPage=1 -q',
)

Install(), env.Install()
Installs one or more source files or directories in the specified
target, which must be a directory. The names of the specified
source files or directories remain the same within the
destination directory. The sources may be given as a string or as
a node returned by a builder.

env.Install(target='/usr/local/bin', source=['foo', 'bar'])

Note that if target paths chosen for the Install builder (and the
related InstallAs and InstallVersionedLib builders) are outside
the project tree, such as in the example above, they may not be
selected for "building" by default, since in the absence of other
instructions scons builds targets that are underneath the top
directory (the directory that contains the SConstruct file,
usually the current directory). Use command line targets or the
Default function in this case.

If the --install-sandbox command line option is given, the target
directory will be prefixed by the directory path specified. This
is useful to test installation behavior without installing to a
"live" location in the system.

See also FindInstalledFiles. For more thoughts on installation,
see the User Guide (particularly the section on Command-Line
Targets and the chapters on Installing Files and on Alias
Targets).

InstallAs(), env.InstallAs()
Installs one or more source files or directories to specific
names, allowing changing a file or directory name as part of the
installation. It is an error if the target and source arguments
list different numbers of files or directories.

env.InstallAs(target='/usr/local/bin/foo',
source='foo_debug')
env.InstallAs(target=['../lib/libfoo.a', '../lib/libbar.a'],
source=['libFOO.a', 'libBAR.a'])

See the note under Install.

InstallVersionedLib(), env.InstallVersionedLib()
Installs a versioned shared library. The symlinks appropriate to
the architecture will be generated based on symlinks of the
source library.

env.InstallVersionedLib(target='/usr/local/bin/foo',
source='libxyz.1.5.2.so')

See the note under Install.

Jar(), env.Jar()
Builds a Java archive (.jar) file from the specified list of
sources. Any directories in the source list will be searched for
.class files). Any .java files in the source list will be
compiled to .class files by calling the Java Builder.

If the $JARCHDIR value is set, the jar command will change to the
specified directory using the -C option. If $JARCHDIR is not set
explicitly, SCons will use the top of any subdirectory tree in
which Java .class were built by the Java Builder.

If the contents any of the source files begin with the string
Manifest-Version, the file is assumed to be a manifest and is
passed to the jar command with the m option set.

env.Jar(target = 'foo.jar', source = 'classes')

env.Jar(target = 'bar.jar',
source = ['bar1.java', 'bar2.java'])

Java(), env.Java()
Builds one or more Java class files. The sources may be any
combination of explicit .java files, or directory trees which
will be scanned for .java files.

SCons will parse each source .java file to find the classes
(including inner classes) defined within that file, and from that
figure out the target .class files that will be created. The
class files will be placed underneath the specified target
directory.

SCons will also search each Java file for the Java package name,
which it assumes can be found on a line beginning with the string
package in the first column; the resulting .class files will be
placed in a directory reflecting the specified package name. For
example, the file Foo.java defining a single public Foo class and
containing a package name of sub.dir will generate a
corresponding sub/dir/Foo.class class file.

Examples:

env.Java(target='classes', source='src')
env.Java(target='classes', source=['src1', 'src2'])
env.Java(target='classes', source=['File1.java', 'File2.java'])


Java source files can use the native encoding for the underlying
OS. Since SCons compiles in simple ASCII mode by default, the
compiler will generate warnings about unmappable characters,
which may lead to errors as the file is processed further. In
this case, the user must specify the LANG environment variable to
tell the compiler what encoding is used. For portability, it's
best if the encoding is hard-coded, so that the compilation works
when run on a system with a different encoding.

env = Environment()
env['ENV']['LANG'] = 'en_GB.UTF-8'


JavaH(), env.JavaH()
Builds C header and source files for implementing Java native
methods. The target can be either a directory in which the header
files will be written, or a header file name which will contain
all of the definitions. The source can be the names of .class
files, the names of .java files to be compiled into .class files
by calling the Java builder method, or the objects returned from
the Java builder method.

If the construction variable $JAVACLASSDIR is set, either in the
environment or in the call to the JavaH builder method itself,
then the value of the variable will be stripped from the
beginning of any .class file names.

Examples:

# builds java_native.h
classes = env.Java(target="classdir", source="src")
env.JavaH(target="java_native.h", source=classes)

# builds include/package_foo.h and include/package_bar.h
env.JavaH(target="include", source=["package/foo.class", "package/bar.class"])

# builds export/foo.h and export/bar.h
env.JavaH(
target="export",
source=["classes/foo.class", "classes/bar.class"],
JAVACLASSDIR="classes",
)

Note
Java versions starting with 10.0 no longer use the javah
command for generating JNI headers/sources, and indeed have
removed the command entirely (see Java Enhancement Proposal
JEP 313[3]), making this tool harder to use for that purpose.
SCons may autodiscover a javah belonging to an older release
if there are multiple Java versions on the system, which will
lead to incorrect results. To use with a newer Java, override
the default values of $JAVAH (to contain the path to the
javac) and $JAVAHFLAGS (to contain at least a -h flag) and
note that generating headers with javac requires supplying
source .java files only, not .class files.

Library(), env.Library()
A synonym for the StaticLibrary builder method.

LoadableModule(), env.LoadableModule()
On most systems, this is the same as SharedLibrary. On Mac OS X
(Darwin) platforms, this creates a loadable module bundle.

M4(), env.M4()
Builds an output file from an M4 input file. This uses a default
$M4FLAGS value of -E, which considers all warnings to be fatal
and stops on the first warning when using the GNU version of m4.
Example:

env.M4(target = 'foo.c', source = 'foo.c.m4')

Moc(), env.Moc()
Builds an output file from a moc input file. moc input files are
either header files or C++ files. This builder is only available
after using the tool qt3. See the $QT3DIR variable for more
information. Example:

env.Moc('foo.h') # generates moc_foo.cc
env.Moc('foo.cpp') # generates foo.moc

MOFiles(), env.MOFiles()
This builder is set up by the msgfmt tool. The builder compiles
PO files to MO files. MOFiles is a single-source builder. The
source parameter can also be omitted if $LINGUAS_FILE is set.


Example 1. Create pl.mo and en.mo by compiling pl.po and en.po:

env.MOFiles(['pl', 'en'])


Example 2. Compile files for languages defined in LINGUAS file:

env.MOFiles(LINGUAS_FILE=True)


Example 3. Create pl.mo and en.mo by compiling pl.po and en.po
plus files for languages defined in LINGUAS file:

env.MOFiles(['pl', 'en'], LINGUAS_FILE=True)


Example 4. Compile files for languages defined in LINGUAS file
(another version):

env['LINGUAS_FILE'] = True
env.MOFiles()

MSVSProject(), env.MSVSProject()
Build a Microsoft Visual C++ project file and solution file.

Builds a Microsoft Visual C++ project file based on the version
of Visual Studio (or to be more precise, of MSBuild) that is
configured: either the latest installed version, or the version
specified by $MSVC_VERSION in the current construction
environment. For Visual Studio 6.0 a .dsp file is generated. For
Visual Studio versions 2002-2008, a .vcproj file is generated.
For Visual Studio 2010 and later a .vcxproj file is generated.
Note there are multiple versioning schemes involved in the
Microsoft compilation environment - see the description of
$MSVC_VERSION for equivalences. Note SCons does not know how to
construct project files for other languages (e.g. .csproj for
C#, .vbproj for Visual Basic or .pyproject for Python).

For the .vcxproj file, the underlying format is the MSBuild XML
Schema, and the details conform to:
https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-file-structure[4].
The generated solution file enables Visual Studio to understand
the project structure, and allows building it using MSBuild to
call back to SCons. The project file encodes a toolset version
that has been selected by SCons as described above. Since recent
Visual Studio versions support multiple concurrent toolsets, use
$MSVC_VERSION to select the desired one if it does not match the
SCons default. The project file also includes entries which
describe how to call SCons to build the project from within
Visual Studio (or from an MSBuild command line). In some
situations SCons may generate this incorrectly - notably when
using the scons-local distribution, which is not installed in a
way that that matches the default invocation line. If so, the
$SCONS_HOME construction variable can be used to describe the
right way to locate the SCons code so that it can be imported.

By default, a matching solution file for the project is also
generated. This behavior may be disabled by specifying
auto_build_solution=0 to the MSVSProject builder. The solution
file can also be independently generated by calling the
MSVSSolution builder, such as in the case where a solution should
describe multiple projects. See the MSVSSolution description for
further information.

The MSVSProject builder accepts several keyword arguments
describing lists of filenames to be placed into the project file.
Currently, srcs, incs, localincs, resources, and misc are
recognized. The names are intended to be self-explanatory, but
note that the filenames need to be specified as strings, not as
SCons File Nodes (for example if you generate files for inclusion
by using the Glob function, the results should be converted to a
list of strings before passing them to MSVSProject). This is
because Visual Studio and MSBuild know nothing about SCons Node
types. Each of the filename lists are individually optional, but
at least one list must be specified for the resulting project
file to be non-empty.

In addition to the above lists of values, the following values
may be specified as keyword arguments:

target
The name of the target .dsp or .vcproj file. The correct
suffix for the version of Visual Studio must be used, but the
$MSVSPROJECTSUFFIX construction variable will be defined to
the correct value (see example below).

variant
The name of this particular variant. Except for Visual Studio
6 projects, this can also be a list of variant names. These
are typically things like "Debug" or "Release", but really
can be anything you want. For Visual Studio 7 projects, they
may also specify a target platform separated from the variant
name by a | (vertical pipe) character: Debug|Xbox. The
default target platform is Win32. Multiple calls to
MSVSProject with different variants are allowed; all variants
will be added to the project file with their appropriate
build targets and sources.

cmdargs
Additional command line arguments for the different variants.
The number of cmdargs entries must match the number of
variant entries, or be empty (not specified). If you give
only one, it will automatically be propagated to all
variants.

cppdefines
Preprocessor definitions for the different variants. The
number of cppdefines entries must match the number of variant
entries, or be empty (not specified). If you give only one,
it will automatically be propagated to all variants. If you
don't give this parameter, SCons will use the invoking
environment's $CPPDEFINES entry for all variants.

cppflags
Compiler flags for the different variants. If a /std:c++ flag
is found then /Zc:__cplusplus is appended to the flags if not
already found, this ensures that Intellisense uses the
/std:c++ switch. The number of cppflags entries must match
the number of variant entries, or be empty (not specified).
If you give only one, it will automatically be propagated to
all variants. If you don't give this parameter, SCons will
combine the invoking environment's $CCFLAGS, $CXXFLAGS,
$CPPFLAGS entries for all variants.

cpppaths
Compiler include paths for the different variants. The number
of cpppaths entries must match the number of variant entries,
or be empty (not specified). If you give only one, it will
automatically be propagated to all variants. If you don't
give this parameter, SCons will use the invoking
environment's $CPPPATH entry for all variants.

buildtarget
An optional string, node, or list of strings or nodes (one
per build variant), to tell the Visual Studio debugger what
output target to use in what build variant. The number of
buildtarget entries must match the number of variant entries.

runfile
The name of the file that Visual Studio 7 and later will run
and debug. This appears as the value of the Output field in
the resulting Microsoft Visual C++ project file. If this is
not specified, the default is the same as the specified
buildtarget value.


Note

SCons and Microsoft Visual Studio understand projects in
different ways, and the mapping is sometimes imperfect:

Because SCons always executes its build commands from the
directory in which the SConstruct file is located, if you
generate a project file in a different directory than the
directory of the SConstruct file, users will not be able to
double-click on the file name in compilation error messages
displayed in the Visual Studio console output window. This
can be remedied by adding the Microsoft Visual C++ /FC
compiler option to the $CCFLAGS variable so that the compiler
will print the full path name of any files that cause
compilation errors.

If the project file is only used to teach the Visual Studio
project browser about the file layout there should be no
issues, However, Visual Studio should not be used to make
changes to the project structure, build options, etc. as
these will (a) not feed back to the SCons description of the
project and (b) be lost if SCons regenerates the project
file. The SConscript files should remain the definitive
description of the build.

If the project file is used to drive MSBuild (such as
selecting "build" from the Visual Studio interface) you lose
the direct control of target selection and command-line
options you would have if launching the build directly from
SCons, because these will be hard-coded in the project file
to the values specified in the MSVSProject call. You can
regain some of this control by defining multiple variants,
using multiple MSVSProject calls to arrange different build
targets, arguments, defines, flags and paths for different
variants.

If the build is divided into a solution with multiple MSBuild
projects the mapping is further strained. In this case, it is
important not to set Visual Studio to do parallel builds, as
it will then launch the separate project builds in parallel,
and SCons does not work well if called that way. Instead, you
can set up the SCons build for parallel building - see the
SetOption function for how to do this with num_jobs.
Example usage:

barsrcs = ['bar.cpp']
barincs = ['bar.h']
barlocalincs = ['StdAfx.h']
barresources = ['bar.rc', 'resource.h']
barmisc = ['bar_readme.txt']

dll = env.SharedLibrary(target='bar.dll', source=barsrcs)
buildtarget = [s for s in dll if str(s).endswith('dll')]
env.MSVSProject(
target='Bar' + env['MSVSPROJECTSUFFIX'],
srcs=barsrcs,
incs=barincs,
localincs=barlocalincs,
resources=barresources,
misc=barmisc,
buildtarget=buildtarget,
variant='Release',
)


DebugSettings
A dictionary of debug settings that get written to the
.vcproj.user or the .vcxproj.user file, depending on the
version installed. As for cmdargs, you can specify a
DebugSettings dictionary per variant. If you give only one,
it will be propagated to all variants.


Changed in version 2.4: Added the optional DebugSettings
parameter.

Currently, only Visual Studio v9.0 and Visual Studio version v11
are implemented, for other versions no file is generated. To
generate the user file, you just need to add a DebugSettings
dictionary to the environment with the right parameters for your
MSVS version. If the dictionary is empty, or does not contain any
good value, no file will be generated.

Following is a more contrived example, involving the setup of a
project for variants and DebugSettings:

# Assuming you store your defaults in a file
vars = Variables('variables.py')
msvcver = vars.args.get('vc', '9')

# Check command args to force one Microsoft Visual Studio version
if msvcver == '9' or msvcver == '11':
env = Environment(MSVC_VERSION=msvcver + '.0', MSVC_BATCH=False)
else:
env = Environment()

AddOption(
'--userfile',
action='store_true',
dest='userfile',
default=False,
help="Create Visual C++ project file",
)

#
# 1. Configure your Debug Setting dictionary with options you want in the list
# of allowed options, for instance if you want to create a user file to launch
# a specific application for testing your dll with Microsoft Visual Studio 2008 (v9):
#
V9DebugSettings = {
'Command': 'c:\\myapp\\using\\thisdll.exe',
'WorkingDirectory': 'c:\\myapp\\using\\',
'CommandArguments': '-p password',
# 'Attach':'false',
# 'DebuggerType':'3',
# 'Remote':'1',
# 'RemoteMachine': None,
# 'RemoteCommand': None,
# 'HttpUrl': None,
# 'PDBPath': None,
# 'SQLDebugging': None,
# 'Environment': '',
# 'EnvironmentMerge':'true',
# 'DebuggerFlavor': None,
# 'MPIRunCommand': None,
# 'MPIRunArguments': None,
# 'MPIRunWorkingDirectory': None,
# 'ApplicationCommand': None,
# 'ApplicationArguments': None,
# 'ShimCommand': None,
# 'MPIAcceptMode': None,
# 'MPIAcceptFilter': None,
}

#
# 2. Because there are a lot of different options depending on the Microsoft
# Visual Studio version, if you use more than one version you have to
# define a dictionary per version, for instance if you want to create a user
# file to launch a specific application for testing your dll with Microsoft
# Visual Studio 2012 (v11):
#
V10DebugSettings = {
'LocalDebuggerCommand': 'c:\\myapp\\using\\thisdll.exe',
'LocalDebuggerWorkingDirectory': 'c:\\myapp\\using\\',
'LocalDebuggerCommandArguments': '-p password',
# 'LocalDebuggerEnvironment': None,
# 'DebuggerFlavor': 'WindowsLocalDebugger',
# 'LocalDebuggerAttach': None,
# 'LocalDebuggerDebuggerType': None,
# 'LocalDebuggerMergeEnvironment': None,
# 'LocalDebuggerSQLDebugging': None,
# 'RemoteDebuggerCommand': None,
# 'RemoteDebuggerCommandArguments': None,
# 'RemoteDebuggerWorkingDirectory': None,
# 'RemoteDebuggerServerName': None,
# 'RemoteDebuggerConnection': None,
# 'RemoteDebuggerDebuggerType': None,
# 'RemoteDebuggerAttach': None,
# 'RemoteDebuggerSQLDebugging': None,
# 'DeploymentDirectory': None,
# 'AdditionalFiles': None,
# 'RemoteDebuggerDeployDebugCppRuntime': None,
# 'WebBrowserDebuggerHttpUrl': None,
# 'WebBrowserDebuggerDebuggerType': None,
# 'WebServiceDebuggerHttpUrl': None,
# 'WebServiceDebuggerDebuggerType': None,
# 'WebServiceDebuggerSQLDebugging': None,
}

#
# 3. Select the dictionary you want depending on the version of Visual Studio
# Files you want to generate.
#
if not env.GetOption('userfile'):
dbgSettings = None
elif env.get('MSVC_VERSION', None) == '9.0':
dbgSettings = V9DebugSettings
elif env.get('MSVC_VERSION', None) == '11.0':
dbgSettings = V10DebugSettings
else:
dbgSettings = None

#
# 4. Add the dictionary to the DebugSettings keyword.
#
barsrcs = ['bar.cpp', 'dllmain.cpp', 'stdafx.cpp']
barincs = ['targetver.h']
barlocalincs = ['StdAfx.h']
barresources = ['bar.rc', 'resource.h']
barmisc = ['ReadMe.txt']

dll = env.SharedLibrary(target='bar.dll', source=barsrcs)

env.MSVSProject(
target='Bar' + env['MSVSPROJECTSUFFIX'],
srcs=barsrcs,
incs=barincs,
localincs=barlocalincs,
resources=barresources,
misc=barmisc,
buildtarget=[dll[0]] * 2,
variant=('Debug|Win32', 'Release|Win32'),
cmdargs=f'vc={msvcver}',
DebugSettings=(dbgSettings, {}),
)


MSVSSolution(), env.MSVSSolution()
Build a Microsoft Visual Studio Solution file.

Builds a Visual Studio solution file based on the version of
Visual Studio that is configured: either the latest installed
version, or the version specified by $MSVC_VERSION in the
construction environment. For Visual Studio 6, a .dsw file is
generated. For Visual Studio .NET 2002 and later, it will
generate a .sln file. Note there are multiple versioning schemes
involved in the Microsoft compilation environment - see the
description of $MSVC_VERSION for equivalences.

The solution file is a container for one or more projects, and
follows the format described at
https://learn.microsoft.com/en-us/visualstudio/extensibility/internals/solution-dot-sln-file[5].

The following values must be specified:

target
The name of the target .dsw or .sln file. The correct suffix
for the version of Visual Studio must be used, but the value
$MSVSSOLUTIONSUFFIX will be defined to the correct value (see
example below).

variant
The name of this particular variant, or a list of variant
names (the latter is only supported for MSVS 7 solutions).
These are typically things like "Debug" or "Release", but
really can be anything you want. For MSVS 7 they may also
specify target platform, like this "Debug|Xbox". Default
platform is Win32.

projects
A list of project file names, or Project nodes returned by
calls to the MSVSProject Builder, to be placed into the
solution file. Note that these filenames need to be specified
as strings, NOT as SCons File Nodes. This is because the
solution file will be interpreted by MSBuild and by Visual
Studio, which know nothing about SCons Node types.

In addition to the mandatory arguments above, the following
optional values may be specified as keyword arguments:

auto_filter_projects
Under certain circumstances, solution file names or solution
file nodes may be present in the projects argument list. When
solution file names or nodes are present in the projects
argument list, the generated solution file may contain
erroneous Project records resulting in VS IDE error messages
when opening the generated solution file. By default, an
exception is raised when a solution file name or solution
file node is detected in the projects argument list.

The accepted values for auto_filter_projects are:

None
An exception is raised when a solution file name or
solution file node is detected in the projects argument
list.


None is the default value.

True or evaluates True
Automatically remove solution file names and solution
file nodes from the projects argument list.

False or evaluates False
Leave the solution file names and solution file nodes in
the projects argument list. An exception is not raised.

When opening the generated solution file with the VS IDE,
the VS IDE will likely report that there are erroneous
Project records that are not supported or that need to be
modified.

Example Usage:

env.MSVSSolution(
target="Bar" + env["MSVSSOLUTIONSUFFIX"],
projects=["bar" + env["MSVSPROJECTSUFFIX"]],
variant="Release",
)


Ninja(), env.Ninja()
A special builder which adds a target to create a Ninja build
file. The builder does not require any source files to be
specified.

Note
This is an experimental feature. To enable it you must use
one of the following methods

# On the command line
--experimental=ninja

# Or in your SConstruct
SetOption('experimental', 'ninja')


This functionality is subject to change and/or removal
without deprecation cycle.

To use this tool you need to install the Python ninja
package, as the tool by default depends on being able to do
an import of the package This can be done via:

python -m pip install ninja

If called with no arguments, the builder will default to a target
name of ninja.build.

If called with a single positional argument, scons will "deduce"
the target name from that source argument, giving it the same
name, and then ignore the source. This is the usual way to call
the builder if a non-default target name is wanted.

If called with either the target= or source= keyword arguments,
the value of the argument is taken as the target name. If called
with both, the target= value is used and source= is ignored. If
called with multiple sources, the source list will be ignored,
since there is no way to deduce what the intent was; in this case
the default target name will be used.


Available since scons 4.2.

Object(), env.Object()
A synonym for the StaticObject builder method.

Package(), env.Package()
Builds software distribution packages. A package is a container
format which includes files to install along with metadata.
Packaging is optional, and must be enabled by specifying the
packaging tool. For example:

env = Environment(tools=['default', 'packaging'])


SCons can build packages in a number of well known packaging
formats. The target package type may be selected with the
$PACKAGETYPE construction variable or the --package-type command
line option. The package type may be a list, in which case SCons
will attempt to build packages for each type in the list.
Example:

env.Package(PACKAGETYPE=['src_zip', 'src_targz'], ...other args...)

The currently supported packagers are:

+-----------+---------------------------+
|msi | Microsoft Installer |
| | package |
+-----------+---------------------------+
|rpm | RPM Package Manager |
| | package |
+-----------+---------------------------+
|ipkg | Itsy Package Management |
| | package |
+-----------+---------------------------+
|tarbz2 | bzip2-compressed tar file |
+-----------+---------------------------+
|targz | gzip-compressed tar file |
+-----------+---------------------------+
|tarxz | xz-compressed tar file |
+-----------+---------------------------+
|zip | zip file |
+-----------+---------------------------+
|src_tarbz2 | bzip2-compressed tar file |
| | suitable as source to |
| | another packager |
+-----------+---------------------------+
|src_targz | gzip-compressed tar file |
| | suitable as source to |
| | another packager |
+-----------+---------------------------+
|src_tarxz | xz-compressed tar file |
| | suitable as source to |
| | another packager |
+-----------+---------------------------+
|src_zip | zip file suitable as |
| | source to another |
| | packager |
+-----------+---------------------------+
The file list to include in the package may be specified with the
source keyword argument. If omitted, the FindInstalledFiles
function is called behind the scenes to select all files that
have an Install, InstallAs or InstallVersionedLib Builder
attached. If the target keyword argument is omitted, the target
name(s) will be deduced from the package type(s).

The metadata comes partly from attributes of the files to be
packaged, and partly from packaging tags. Tags can be passed as
keyword arguments to the Package builder call, and may also be
attached to files (or more accurately, Nodes representing files)
with the Tag function. Some package-level tags are mandatory, and
will lead to errors if omitted. The mandatory tags vary depending
on the package type.

While packaging, the builder uses a temporary location named by
the value of the $PACKAGEROOT variable - the package sources are
copied there before packaging.

Packaging example:

env = Environment(tools=["default", "packaging"])
env.Install("/bin/", "my_program")
env.Package(
NAME="foo",
VERSION="1.2.3",
PACKAGEVERSION=0,
PACKAGETYPE="rpm",
LICENSE="gpl",
SUMMARY="balalalalal",
DESCRIPTION="this should be really really long",
X_RPM_GROUP="Application/fu",
SOURCE_URL="https://foo.org/foo-1.2.3.tar.gz",
)

In this example, the target /bin/my_program created by the
Install call would not be built by default since it is not under
the project top directory. However, since no source is specified
to the Package builder, it is selected for packaging by the
default sources rule. Since packaging is done using $PACKAGEROOT,
no write is actually done to the system's /bin directory, and the
target will be selected since after rebasing to underneath
$PACKAGEROOT it is now under the top directory of the project.

PCH(), env.PCH()
Builds a Microsoft Visual C++ precompiled header. Calling this
builder returns a list of two target nodes: the PCH as the first
element, and the object file as the second element. Normally the
object file is ignored. The PCH builder is generally used in
conjunction with the $PCH construction variable to force object
files to use the precompiled header:

env['PCH'] = env.PCH('StdAfx.cpp')[0]

Note
This builder is specific to the PCH implementation in
Microsoft Visual C++. Other compiler chains also implement
precompiled header support, but PCH does not work with them
at this time. As a result, the builder is only generated into
the construction environment when Microsoft Visual C++ is
being used as the compiler.

The builder only works correctly in a C++ project. The
Microsoft implementation distinguishes between precompiled
headers from C and C++. Use of the builder will cause the PCH
generation to happen with a flag that tells cl.exe all of the
files are C++ files; if that PCH file is then supplied when
compiling a C source file, cl.exe will fail the build with a
compatibility violation.

If possible, arrange the project so that a C++ source file
passed to the PCH builder is not also included in the list of
sources to be otherwise compiled in the project. SCons will
correctly track that file in the dependency tree as a result
of the PCH call, and (for MSVC 11.0 and greater)
automatically add the corresponding object file to the link
line. If the source list is automatically generated, for
example using the Glob function, it may be necessary to
remove that file from the list.

PDF(), env.PDF()
Builds a .pdf file from a .dvi input file (or, by extension, a
.tex, .ltx, or .latex input file). The suffix specified by the
$PDFSUFFIX construction variable (.pdf by default) is added
automatically to the target if it is not already present. PDF is
a single-source builder. Example:

# builds from aaa.tex
env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
# builds bbb.pdf from bbb.dvi
env.PDF(target = 'bbb', source = 'bbb.dvi')

POInit(), env.POInit()
This builder is set up by the msginit tool. The builder
initializes missing PO file(s) if $POAUTOINIT is set. If
$POAUTOINIT is not set (the default), POInit prints instruction
for the user (such as a translator), telling how the PO file
should be initialized. In normal projects you should not use
POInit and use POUpdate instead. POUpdate chooses intelligently
between msgmerge(1) and msginit(1). POInit always uses
msginit(1) and should be regarded as builder for special purposes
or for temporary use (e.g. for quick, one time initialization of
a bunch of PO files) or for tests. POInit is a single-source
builder. The source parameter can also be omitted if
$LINGUAS_FILE is set.

Target nodes defined through POInit are not built by default
(they're Ignored from '.' node) but are added to special Alias
('po-create' by default). The alias name may be changed through
the $POCREATE_ALIAS construction variable. All PO files defined
through POInit may be easily initialized by scons po-create.


Example 1. Initialize en.po and pl.po from messages.pot:

env.POInit(['en', 'pl']) # messages.pot --> [en.po, pl.po]


Example 2. Initialize en.po and pl.po from foo.pot:

env.POInit(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.po]


Example 3. Initialize en.po and pl.po from foo.pot but using the
$POTDOMAIN construction variable:

env.POInit(['en', 'pl'], POTDOMAIN='foo') # foo.pot --> [en.po, pl.po]


Example 4. Initialize PO files for languages defined in LINGUAS
file. The files will be initialized from template messages.pot:

env.POInit(LINGUAS_FILE=True) # needs 'LINGUAS' file


Example 5. Initialize en.po and pl.pl PO files plus files for
languages defined in LINGUAS file. The files will be initialized
from template messages.pot:

env.POInit(['en', 'pl'], LINGUAS_FILE=True)


Example 6. You may preconfigure your environment first, and then
initialize PO files:

env['POAUTOINIT'] = True
env['LINGUAS_FILE'] = True
env['POTDOMAIN'] = 'foo'
env.POInit()

which has same efect as:

env.POInit(POAUTOINIT=True, LINGUAS_FILE=True, POTDOMAIN='foo')

PostScript(), env.PostScript()
Builds a .ps file from a .dvi input file (or, by extension, a
.tex, .ltx, or .latex input file). The suffix specified by the
$PSSUFFIX construction variable (.ps by default) is added
automatically to the target if it is not already present.
PostScript is a single-source builder. Example:

# builds from aaa.tex
env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
# builds bbb.ps from bbb.dvi
env.PostScript(target = 'bbb', source = 'bbb.dvi')

POTUpdate(), env.POTUpdate()
The builder is set up by the xgettext tool, part of the gettext
toolset. The builder updates the target POT file if exists or
creates it if it doesn't. The target node is not selected for
building by default (e.g. scons .), but only on demand (i.e.
when the given POT file is required or when special alias is
invoked). This builder adds its target node (messages.pot, say)
to a special alias (pot-update by default, see $POTUPDATE_ALIAS)
so you can update/create them easily with scons pot-update. The
file is not written until there is no real change in
internationalized messages (or in comments that enter POT file).


Note
You may see xgettext(1) being invoked by the xgettext tool
even if there is no real change in internationalized messages
(so the POT file is not being updated). This happens every
time a source file has changed. In such case we invoke
xgettext(1) and compare its output with the content of POT
file to decide whether the file should be updated or not.


Example 1. Let's create po/ directory and place following
SConstruct script there:

# SConstruct in 'po/' subdir
env = Environment(tools=['default', 'xgettext'])
env.POTUpdate(['foo'], ['../a.cpp', '../b.cpp'])
env.POTUpdate(['bar'], ['../c.cpp', '../d.cpp'])

Then invoke scons few times:

$ scons # Does not create foo.pot nor bar.pot
$ scons foo.pot # Updates or creates foo.pot
$ scons pot-update # Updates or creates foo.pot and bar.pot
$ scons -c # Does not clean foo.pot nor bar.pot.

the results shall be as the comments above say.


Example 2. The target argument can be omitted, in which case the
default target name messages.pot is used. The target may also be
overridden by setting the $POTDOMAIN construction variable or
providing it as an override to the POTUpdate builder:

# SConstruct script
env = Environment(tools=['default', 'xgettext'])
env['POTDOMAIN'] = "foo"
env.POTUpdate(source=["a.cpp", "b.cpp"]) # Creates foo.pot ...
env.POTUpdate(POTDOMAIN="bar", source=["c.cpp", "d.cpp"]) # and bar.pot


Example 3. The source parameter may also be omitted, if it is
specified in a separate file, for example POTFILES.in:

# POTFILES.in in 'po/' subdirectory
../a.cpp
../b.cpp
# end of file

The name of the file (POTFILES.in) containing the list of sources
is provided via $XGETTEXTFROM:

# SConstruct file in 'po/' subdirectory
env = Environment(tools=['default', 'xgettext'])
env.POTUpdate(XGETTEXTFROM='POTFILES.in')


Example 4. You can use $XGETTEXTPATH to define the source search
path. Assume, for example, that you have files a.cpp, b.cpp,
po/SConstruct, po/POTFILES.in. Then your POT-related files could
look like this:

# POTFILES.in in 'po/' subdirectory
a.cpp
b.cpp
# end of file

# SConstruct file in 'po/' subdirectory
env = Environment(tools=['default', 'xgettext'])
env.POTUpdate(XGETTEXTFROM='POTFILES.in', XGETTEXTPATH='../')


Example 5. Multiple search directories may be defined as a list,
i.e. XGETTEXTPATH=['dir1', 'dir2', ...]. The order in the list
determines the search order of source files. The path to the
first file found is used.

Let's create 0/1/po/SConstruct script:

# SConstruct file in '0/1/po/' subdirectory
env = Environment(tools=['default', 'xgettext'])
env.POTUpdate(XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../', '../../'])

and 0/1/po/POTFILES.in:

# POTFILES.in in '0/1/po/' subdirectory
a.cpp
# end of file

Write two *.cpp files, the first one is 0/a.cpp:

/* 0/a.cpp */
gettext("Hello from ../../a.cpp")

and the second is 0/1/a.cpp:

/* 0/1/a.cpp */
gettext("Hello from ../a.cpp")

then run scons. You'll obtain 0/1/po/messages.pot with the
message "Hello from ../a.cpp". When you reverse order in
$XGETTEXTFOM, i.e. when you write SConscript as

# SConstruct file in '0/1/po/' subdirectory
env = Environment(tools=['default', 'xgettext'])
env.POTUpdate(XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../../', '../'])

then the messages.pot will contain msgid "Hello from ../../a.cpp"
line and not msgid "Hello from ../a.cpp".

POUpdate(), env.POUpdate()
The builder is set up by the msgmerge tool. part of the gettext
toolset. The builder updates PO files with msgmerge(1), or
initializes missing PO files as described in the documentation of
the msginit tool and the POInit builder (see also $POAUTOINIT).
POUpdate is a single-source builder. The source parameter can
also be omitted if $LINGUAS_FILE is set.

The target nodes are not selected for building by default (e.g.
scons .). Instead, they are added automatically to special Alias
('po-update' by default). The alias name may be changed through
the $POUPDATE_ALIAS construction variable. You can easily update
PO files in your project by scons po-update. Note that POUpdate
does not add its targets to the po-create alias as POInit does.


Example 1. Update en.po and pl.po from messages.pot template (see
also $POTDOMAIN), assuming that the later one exists or there is
rule to build it (see POTUpdate):

env.POUpdate(['en','pl']) # messages.pot --> [en.po, pl.po]


Example 2. Update en.po and pl.po from foo.pot template:

env.POUpdate(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.pl]


Example 3. Update en.po and pl.po from foo.pot (another version):

env.POUpdate(['en', 'pl'], POTDOMAIN='foo') # foo.pot -- > [en.po, pl.pl]


Example 4. Update files for languages defined in LINGUAS file.
The files are updated from messages.pot template:

env.POUpdate(LINGUAS_FILE=True) # needs 'LINGUAS' file


Example 5. Same as above, but update from foo.pot template:

env.POUpdate(LINGUAS_FILE=True, source=['foo'])


Example 6. Update en.po and pl.po plus files for languages
defined in LINGUAS file. The files are updated from messages.pot
template:

# produce 'en.po', 'pl.po' + files defined in 'LINGUAS':
env.POUpdate(['en', 'pl' ], LINGUAS_FILE=True)


Example 7. Use $POAUTOINIT to automatically initialize PO file if
it doesn't exist:

env.POUpdate(LINGUAS_FILE=True, POAUTOINIT=True)


Example 8. Update PO files for languages defined in LINGUAS file.
The files are updated from foo.pot template. All necessary
settings are pre-configured via environment.

env['POAUTOINIT'] = True
env['LINGUAS_FILE'] = True
env['POTDOMAIN'] = 'foo'
env.POUpdate()

Program(), env.Program()
Builds an executable given one or more object files or C, C++, D,
or Fortran source files. If any C, C++, D or Fortran source files
are specified, then they will be automatically compiled to object
files using the Object builder method; see that builder method's
description for a list of legal source file suffixes and how they
are interpreted. The target executable file prefix, specified by
the $PROGPREFIX construction variable (nothing by default), and
suffix, specified by the $PROGSUFFIX construction variable (by
default, .exe on Windows systems, nothing on POSIX systems), are
automatically added to the target if not already present.
Example:

env.Program(target='foo', source=['foo.o', 'bar.c', 'baz.f'])

ProgramAllAtOnce(), env.ProgramAllAtOnce()
Builds an executable from D sources without first creating
individual objects for each file.

D sources can be compiled file-by-file as C and C++ source are,
and D is integrated into the scons Object and Program builders
for this model of build. D codes can though do whole source
meta-programming (some of the testing frameworks do this). For
this it is imperative that all sources are compiled and linked in
a single call to the D compiler. This builder serves that
purpose.

env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])


This command will compile the modules mod_a, mod_b, and mod_c in
a single compilation process without first creating object files
for the modules. Some of the D compilers will create executable.o
others will not.

RES(), env.RES()
Builds a Microsoft Visual C++ resource file. This builder method
is only provided when Microsoft Visual C++ or MinGW is being used
as the compiler. The .res (or .o for MinGW) suffix is added to
the target name if no other suffix is given. The source file is
scanned for implicit dependencies as though it were a C file.
Example:

env.RES('resource.rc')

RMIC(), env.RMIC()
Builds stub and skeleton class files for remote objects from Java
.class files. The target is a directory relative to which the
stub and skeleton class files will be written. The source can be
the names of .class files, or the objects return from the Java
builder method.

If the construction variable $JAVACLASSDIR is set, either in the
environment or in the call to the RMIC builder method itself,
then the value of the variable will be stripped from the
beginning of any .class file names.

classes = env.Java(target='classdir', source='src')
env.RMIC(target='outdir1', source=classes)
env.RMIC(
target='outdir2',
source=['package/foo.class', 'package/bar.class'],
)
env.RMIC(
target='outdir3',
source=['classes/foo.class', 'classes/bar.class'],
JAVACLASSDIR='classes',
)

RPCGenClient(), env.RPCGenClient()
Generates an RPC client stub (_clnt.c) file from a specified RPC
(.x) source file. Because rpcgen only builds output files in the
local directory, the command will be executed in the source
file's directory by default.

# Builds src/rpcif_clnt.c
env.RPCGenClient('src/rpcif.x')

RPCGenHeader(), env.RPCGenHeader()
Generates an RPC header (.h) file from a specified RPC (.x)
source file. Because rpcgen only builds output files in the local
directory, the command will be executed in the source file's
directory by default.

# Builds src/rpcif.h
env.RPCGenHeader('src/rpcif.x')

RPCGenService(), env.RPCGenService()
Generates an RPC server-skeleton (_svc.c) file from a specified
RPC (.x) source file. Because rpcgen only builds output files in
the local directory, the command will be executed in the source
file's directory by default.

# Builds src/rpcif_svc.c
env.RPCGenClient('src/rpcif.x')

RPCGenXDR(), env.RPCGenXDR()
Generates an RPC XDR routine (_xdr.c) file from a specified RPC
(.x) source file. Because rpcgen only builds output files in the
local directory, the command will be executed in the source
file's directory by default.

# Builds src/rpcif_xdr.c
env.RPCGenClient('src/rpcif.x')

SharedLibrary(), env.SharedLibrary()
Builds a shared library given one or more object files and/or C,
C++, D or Fortran source files. Any source files listed in the
source parameter will be automatically compiled to object files
suitable for use in a shared library. Any object files listed in
the source parameter must have been built for a shared library
(that is, using the SharedObject builder method). scons will
raise an error if there is any mismatch.

The target library file prefix, specified by the $SHLIBPREFIX
construction variable (by default, lib on POSIX systems, nothing
on Windows systems), and suffix, specified by the $SHLIBSUFFIX
construction variable (by default, .dll on Windows systems, .so
on POSIX systems), are automatically added (if not already
present) to the target name to make up the library filename. On a
POSIX system, if the $SHLIBVERSION construction variable is set,
it is appended (following a period) to the resulting library
name.

Example:

env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'])

On Windows systems, the SharedLibrary builder method will always
build an import library (.lib) in addition to the shared library
(.dll), adding a .lib library with the same basename if there is
not already a .lib file explicitly listed in the targets.

On Cygwin systems, the SharedLibrary builder method will always
build an import library (.dll.a) in addition to the shared
library (.dll), adding a .dll.a library with the same basename if
there is not already a .dll.a file explicitly listed in the
targets.

On some platforms, there is a distinction between a shared
library (loaded automatically by the system to resolve external
references) and a loadable module (explicitly loaded by user
action). For maximum portability, use the LoadableModule builder
for the latter.

If $SHLIBVERSION is defined, a versioned shared library is
created. This modifies $SHLINKFLAGS as required, adds the version
number to the library name, and creates any symbolic links that
are needed.

env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'], SHLIBVERSION='1.5.2')

On a POSIX system, supplying a simple version string (no dots)
creates exactly one symbolic link: SHLIBVERSION="1" would create
(for example) library libbar.so.1 and symbolic link libbar.so.
Supplying a dotted version string will create two symbolic links
(irrespective of the number of segments in the version):
SHLIBVERSION="1.5.2" for the same library would create library
libbar.so.1.5.2 and symbolic links libbar.so and libbar.so.1. A
Darwin (OSX) system creates one symlink in either case, for the
second example the library would be libbar.1.5.2.dylib and the
link would be libbar.dylib.

On Windows systems, specifying the register=1 keyword argument
will cause the .dll to be registered after it is built. The
command that is run is determined by the $REGSVR construction
variable (regsvr32 by default), and the flags passed are
determined by $REGSVRFLAGS. By default, $REGSVRFLAGS includes the
/s option, to prevent dialogs from popping up and requiring user
attention when it is run. If you change $REGSVRFLAGS, be sure to
include the /s option. For example,

env.SharedLibrary(target='bar', source=['bar.cxx', 'foo.obj'], register=1)

will register bar.dll as a COM object when it is done linking it.

SharedObject(), env.SharedObject()
Builds an object file intended for inclusion in a shared library.
Source files must have one of the same set of extensions
specified above for the StaticObject builder method. On some
platforms building a shared object requires additional compiler
option (e.g. -fPIC for gcc) in addition to those needed to build
a normal (static) object, but on some platforms there is no
difference between a shared object and a normal (static) one.
When there is a difference, SCons will only allow shared objects
to be linked into a shared library, and will use a different
suffix for shared objects. On platforms where there is no
difference, SCons will allow both normal (static) and shared
objects to be linked into a shared library, and will use the same
suffix for shared and normal (static) objects. The target object
file prefix, specified by the $SHOBJPREFIX construction variable
(by default, the same as $OBJPREFIX), and suffix, specified by
the $SHOBJSUFFIX construction variable, are automatically added
to the target if not already present. Examples:

env.SharedObject(target='ddd', source='ddd.c')
env.SharedObject(target='eee.o', source='eee.cpp')
env.SharedObject(target='fff.obj', source='fff.for')

Note that the source files will be scanned according to the
suffix mappings in the SourceFileScanner object. See the manpage
section "Scanner Objects" for more information.

StaticLibrary(), env.StaticLibrary()
Builds a static library given one or more object files or C, C++,
D or Fortran source files. If any source files are given, then
they will be automatically compiled to object files. The static
library file prefix, specified by the $LIBPREFIX construction
variable (by default, lib on POSIX systems, nothing on Windows
systems), and suffix, specified by the $LIBSUFFIX construction
variable (by default, .lib on Windows systems, .a on POSIX
systems), are automatically added to the target if not already
present. Example:

env.StaticLibrary(target='bar', source=['bar.c', 'foo.o'])

Any object files listed in the source must have been built for a
static library (that is, using the StaticObject builder method).
scons will raise an error if there is any mismatch.

StaticObject(), env.StaticObject()
Builds a static object file from one or more C, C++, D, or
Fortran source files. Source files must have one of the following
extensions:

.asm assembly language file
.ASM assembly language file
.c C file
.C Windows: C file
POSIX: C++ file
.cc C++ file
.cpp C++ file
.cxx C++ file
.cxx C++ file
.c++ C++ file
.C++ C++ file
.d D file
.f Fortran file
.F Windows: Fortran file
POSIX: Fortran file + C pre-processor
.for Fortran file
.FOR Fortran file
.fpp Fortran file + C pre-processor
.FPP Fortran file + C pre-processor
.m Object C file
.mm Object C++ file
.s assembly language file
.S Windows: assembly language file
ARM: CodeSourcery Sourcery Lite
.sx assembly language file + C pre-processor
POSIX: assembly language file + C pre-processor
.spp assembly language file + C pre-processor
.SPP assembly language file + C pre-processor

The target object file prefix, specified by the $OBJPREFIX
construction variable (nothing by default), and suffix, specified
by the $OBJSUFFIX construction variable (.obj on Windows systems,
.o on POSIX systems), are automatically added to the target if
not already present. Examples:

env.StaticObject(target='aaa', source='aaa.c')
env.StaticObject(target='bbb.o', source='bbb.c++')
env.StaticObject(target='ccc.obj', source='ccc.f')

Note that the source files will be scanned according to the
suffix mappings in the SourceFileScanner object. See the manpage
section "Scanner Objects" for more information.

Substfile(), env.Substfile()
The Substfile builder creates a single text file from a template
consisting of a file or set of files (or nodes), replacing text
using the $SUBST_DICT construction variable (if set). If a set,
they are concatenated into the target file using the value of the
$LINESEPARATOR construction variable as a separator between
contents; the separator is not emitted after the contents of the
last file. Nested lists of source files are flattened. See also
Textfile.

By default, the target file encoding is "utf-8" and can be
changed by $FILE_ENCODING Examples:

If a single source file name is specified and has a .in suffix,
the suffix is stripped and the remainder of the name is used as
the default target name.

The prefix and suffix specified by the $SUBSTFILEPREFIX and
$SUBSTFILESUFFIX construction variables (an empty string by
default in both cases) are automatically added to the target if
they are not already present.

If a construction variable named $SUBST_DICT is present, it may
be either a Python dictionary or a sequence of (key, value)
tuples. If it is a dictionary it is converted into a list of
tuples with unspecified order, so if one key is a prefix of
another key or if one substitution could be further expanded by
another substitution, it is unpredictable whether the expansion
will occur.

Any occurrences of a key in the source are replaced by the
corresponding value, which may be a Python callable function or a
string. If the value is a callable, it is called with no
arguments to get a string. Strings are subst-expanded and the
result replaces the key.

env = Environment(tools=['default'])

env['prefix'] = '/usr/bin'
script_dict = {'@prefix@': '/bin', '@exec_prefix@': '$prefix'}
env.Substfile('script.in', SUBST_DICT=script_dict)

conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'}
env.Substfile('config.h.in', conf_dict, SUBST_DICT=conf_dict)

# UNPREDICTABLE - one key is a prefix of another
bad_foo = {'$foo': '$foo', '$foobar': '$foobar'}
env.Substfile('foo.in', SUBST_DICT=bad_foo)

# PREDICTABLE - keys are applied longest first
good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')]
env.Substfile('foo.in', SUBST_DICT=good_foo)

# UNPREDICTABLE - one substitution could be further expanded
bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'}
env.Substfile('bar.in', SUBST_DICT=bad_bar)

# PREDICTABLE - substitutions are expanded in order
good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye'))
env.Substfile('bar.in', SUBST_DICT=good_bar)

# the SUBST_DICT may be in common (and not an override)
substutions = {}
subst = Environment(tools=['textfile'], SUBST_DICT=substitutions)
substitutions['@foo@'] = 'foo'
subst['SUBST_DICT']['@bar@'] = 'bar'
subst.Substfile(
'pgm1.c',
[Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm1.in"],
)
subst.Substfile(
'pgm2.c',
[Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm2.in"],
)


Tar(), env.Tar()
Builds a tar archive of the specified files and/or directories.
Unlike most builder methods, the Tar builder method may be called
multiple times for a given target; each additional call adds to
the list of entries that will be built into the archive. Any
source directories will be scanned for changes to any on-disk
files, regardless of whether or not scons knows about them from
other Builder or function calls.

env.Tar('src.tar', 'src')

# Create the stuff.tar file.
env.Tar('stuff', ['subdir1', 'subdir2'])
# Also add "another" to the stuff.tar file.
env.Tar('stuff', 'another')

# Set TARFLAGS to create a gzip-filtered archive.
env = Environment(TARFLAGS = '-c -z')
env.Tar('foo.tar.gz', 'foo')

# Also set the suffix to .tgz.
env = Environment(TARFLAGS = '-c -z',
TARSUFFIX = '.tgz')
env.Tar('foo')

Textfile(), env.Textfile()
The Textfile builder generates a single text file from a template
consisting of a list of strings, replacing text using the
$SUBST_DICT construction variable (if set) - see Substfile for a
description of replacement. The strings will be separated in the
target file using the value of the $LINESEPARATOR construction
variable; the line separator is not emitted after the last
string. Nested lists of source strings are flattened. Source
strings need not literally be Python strings: they can be Nodes
or Python objects that convert cleanly to Value nodes.

The prefix and suffix specified by the $TEXTFILEPREFIX and
$TEXTFILESUFFIX construction variables (by default an empty
string and .txt, respectively) are automatically added to the
target if they are not already present.

By default, the target file encoding is "utf-8" and can be
changed by $FILE_ENCODING Examples:

# builds/writes foo.txt
env.Textfile(target='foo.txt', source=['Goethe', 42, 'Schiller'])

# builds/writes bar.txt
env.Textfile(target='bar', source=['lalala', 'tanteratei'], LINESEPARATOR='|*')

# nested lists are flattened automatically
env.Textfile(target='blob', source=['lalala', ['Goethe', 42, 'Schiller'], 'tanteratei'])

# files may be used as input by wrapping them in File()
env.Textfile(
target='concat', # concatenate files with a marker between
source=[File('concat1'), File('concat2')],
LINESEPARATOR='====================\n',
)

Results:

foo.txt

Goethe
42
Schiller

bar.txt

lalala|*tanteratei

blob.txt

lalala
Goethe
42
Schiller
tanteratei

Translate(), env.Translate()
This pseudo-Builder is part of the gettext toolset. The builder
extracts internationalized messages from source files, updates
the POT template (if necessary) and then updates PO translations
(if necessary). If $POAUTOINIT is set, missing PO files will be
automatically created (i.e. without translator person
intervention). The variables $LINGUAS_FILE and $POTDOMAIN are
taken into account too. All other construction variables used by
POTUpdate, and POUpdate work here too.


Example 1. The simplest way is to specify input files and output
languages inline in a SCons script when invoking Translate:

# SConscript in 'po/' directory
env = Environment(tools=["default", "gettext"])
env['POAUTOINIT'] = True
env.Translate(['en', 'pl'], ['../a.cpp', '../b.cpp'])


Example 2. If you wish, you may also stick to the conventional
style known from autotools, i.e. using POTFILES.in and LINGUAS
files to specify the targets and sources:

# LINGUAS
en pl
# end

# POTFILES.in
a.cpp
b.cpp
# end

# SConscript
env = Environment(tools=["default", "gettext"])
env['POAUTOINIT'] = True
env['XGETTEXTPATH'] = ['../']
env.Translate(LINGUAS_FILE=True, XGETTEXTFROM='POTFILES.in')

The last approach is perhaps the recommended one. It allows
easily split internationalization/localization onto separate
SCons scripts, where a script in source tree is responsible for
translations (from sources to PO files) and script(s) under
variant directories are responsible for compilation of PO to MO
files to and for installation of MO files. The "gluing factor"
synchronizing these two scripts is then the content of LINGUAS
file. Note, that the updated POT and PO files are usually going
to be committed back to the repository, so they must be updated
within the source directory (and not in variant directories).
Additionally, the file listing of po/ directory contains LINGUAS
file, so the source tree looks familiar to translators, and they
may work with the project in their usual way.


Example 3. Let's prepare a development tree as below

project/
+ SConstruct
+ build/
+ src/
+ po/
+ SConscript
+ SConscript.i18n
+ POTFILES.in
+ LINGUAS

with build being the variant directory. Write the top-level
SConstruct script as follows

# SConstruct
env = Environment(tools=["default", "gettext"])
VariantDir('build', 'src', duplicate=False)
env['POAUTOINIT'] = True
SConscript('src/po/SConscript.i18n', exports='env')
SConscript('build/po/SConscript', exports='env')

the src/po/SConscript.i18n as

# src/po/SConscript.i18n
Import('env')
env.Translate(LINGUAS_FILE=True, XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../'])

and the src/po/SConscript

# src/po/SConscript
Import('env')
env.MOFiles(LINGUAS_FILE=True)

Such a setup produces POT and PO files under the source tree in
src/po/ and binary MO files under the variant tree in build/po/.
This way the POT and PO files are separated from other output
files, which must not be committed back to source repositories
(e.g. MO files).

Note
In the above example, the PO files are not updated, nor
created automatically when you issue the command scons .. The
files must be updated (created) by hand via scons po-update
and then MO files can be compiled by running scons ..

TypeLibrary(), env.TypeLibrary()
Builds a Windows type library (.tlb) file from an input IDL file
(.idl). In addition, it will build the associated interface stub
and proxy source files, naming them according to the base name of
the .idl file. For example,

env.TypeLibrary(source="foo.idl")

Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c
files.

Uic(), env.Uic()
Builds a header file, an implementation file and a moc file from
an ui file. and returns the corresponding nodes in the that
order. This builder is only available after using the tool qt3.
Note: you can specify .ui files directly as source files to the
Program, Library and SharedLibrary builders without using this
builder. Using this builder lets you override the standard naming
conventions (be careful: prefixes are always prepended to names
of built files; if you don't want prefixes, you may set them to
``). See the $QT3DIR variable for more information. Example:

env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
env.Uic(
target=Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
source='foo.ui'
) # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

Zip(), env.Zip()
Builds a zip archive of the specified files and/or directories.
Unlike most builder methods, the Zip builder method may be called
multiple times for a given target; each additional call adds to
the list of entries that will be built into the archive. Any
source directories will be scanned for changes to any on-disk
files, regardless of whether or not scons knows about them from
other Builder or function calls.

env.Zip('src.zip', 'src')

# Create the stuff.zip file.
env.Zip('stuff', ['subdir1', 'subdir2'])
# Also add "another" to the stuff.tar file.
env.Zip('stuff', 'another')

All targets of builder methods automatically depend on their sources.
An explicit dependency can be specified using the env.Depends method
of a construction environment (see below).

In addition, scons automatically scans source files for various
programming languages, so the dependencies do not need to be
specified explicitly. By default, SCons can C source files, C++
source files, Fortran source files with .F (POSIX systems only),
.fpp, or .FPP file extensions, and assembly language files with .S
(POSIX systems only), .spp, or .SPP files extensions for C
preprocessor dependencies. SCons also has default support for
scanning D source files, You can also write your own Scanners to add
support for additional source file types. These can be added to the
default Scanner object used by the Object, StaticObject and
SharedObject Builders by adding them to the SourceFileScanner object.
See the section called "Scanner Objects" for more information about
defining your own Scanner objects and using the SourceFileScanner
object.

SCons Functions and Environment Methods

SCons provides a variety of construction environment methods and
global functions to manipulate the build configuration. Often, a
construction environment method and a global function with the same
name exist for convenience. In this section, both forms are shown if
the function can be called in either way. The documentation style for
these is as follows:

Function(arguments, [optional arguments, ...]) # Global function
env.Function(arguments, [optional arguments, ...]) # Environment method

In these function signatures, arguments in brackets ([]) are
optional, and ellipses (...) indicate possible repetition. Positional
vs. keyword arguments are usually detailed in the following text, not
in the signature itself. The Python positional-only (/) and
keyword-only (*) markers are not used.

When the Python keyword=value style is shown, it can have two
meanings. If the keyword argument is known to the function, the value
is the default for that argument if it is omitted. If the keyword is
unknown to the function, some methods treat it as a construction
variable assignment; otherwise an exception is raised for an unknown
argument.

A global function and a same-named construction environment method
have the same base functionality, with two key differences:

1. Construction environment methods that change the environment act
on the environment instance from which they are called, while the
corresponding global function acts on a special "hidden"
construction environment called the Default Environment. In some
cases, the global function may take an initial argument giving
the object to operate on.

2. String-valued arguments (including strings in list-valued
arguments) are subject to construction variable expansion by the
environment method form; variable expansion is not immediately
performed in the global function. For example,
Default('$MYTARGET') adds '$MYTARGET' to the list of default
targets, while if the value in env of MYTARGET is 'mine',
env.Default('$MYTARGET' adds 'mine' to the default targets. For
more details on construction variable expansion, see the
Construction variables section.

Global functions are automatically in scope inside SConscript files.
If your project adds Python modules that you include via the Python
import statement from an SConscript file, such code will need to add
the functions to that module's global scope explicitly. You can do
that by adding the following import to the Python module: from
SCons.Script import *.

SCons provides the following construction environment methods and
global functions. The list can be augmented on a project basis using
AddMethod

Action(action, [output, [var, ...]] [key=value, ...]),
env.Action(action, [output, [var, ...]] [key=value, ...])
A factory function to create an Action object for the specified
action. See the manpage section "Action Objects" for a complete
explanation of the arguments and behavior.

Note that the env.Action form of the invocation will expand
construction variables in any argument strings, including the
action argument, at the time it is called using the construction
variables in the construction environment through which
env.Action was called. The Action global function form delays all
variable expansion until the Action object is actually used.

AddMethod(object, function, [name]), env.AddMethod(function, [name])
Adds function to an object as a method. function will be called
with an instance object as the first argument as for other
methods. If name is given, it is used as the name of the new
method, else the name of function is used.

When the global function AddMethod is called, the object to add
the method to must be passed as the first argument; typically
this will be Environment, in order to create a method which
applies to all construction environments subsequently
constructed. When called using the env.AddMethod form, the method
is added to the specified construction environment only. Added
methods propagate through env.Clone calls.

More examples:

# Function to add must accept an instance argument.
# The Python convention is to call this 'self'.
def my_method(self, arg):
print("my_method() got", arg)

# Use the global function to add a method to the Environment class:
AddMethod(Environment, my_method)
env = Environment()
env.my_method('arg')

# Use the optional name argument to set the name of the method:
env.AddMethod(my_method, 'other_method_name')
env.other_method_name('another arg')

AddOption(opt_str, ..., attr=value, ...)
Adds a local (project-specific) command-line option. One or more
opt_str values are the strings representing how the option can be
called, while the keyword arguments define attributes of the
option. For the most part these are the same as for the
OptionParser.add_option method in the standard Python library
module optparse, but with a few additional capabilities noted
below. See the optparse documentation[6] for a thorough
discussion of its option-processing capabilities. All options
added through AddOption are placed in a special "Local Options"
option group.

In addition to the arguments and values supported by the optparse
add_option method, AddOption allows setting the nargs keyword
value to a string '?' (question mark) to indicate that the option
argument for that option string may be omitted. If the option
string is present on the command line but has no matching option
argument, the value of the const keyword argument is produced as
the value of the option. If the option string is omitted from the
command line, the value of the default keyword argument is
produced, as usual; if there is no default keyword argument in
the AddOption call, None is produced.


optparse recognizes abbreviations of long option names, as long
as they can be unambiguously resolved. For example, if add_option
is called to define a --devicename option, it will recognize
--device, --dev and so forth as long as there is no other option
which could also match to the same abbreviation. Options added
via AddOption do not support the automatic recognition of
abbreviations. Instead, to allow specific abbreviations, include
them as synonyms in the AddOption call itself.

Once a new command-line option has been added with AddOption, the
option value may be accessed using GetOption or env.GetOption. If
the settable=True argument was supplied in the AddOption call,
the value may also be set later using SetOption or env.SetOption,
if conditions in an SConscript file require overriding any
default value. Note however that a value specified on the command
line will always override a value set in an SConscript file.


Changed in 4.8.0: added the settable keyword argument to enable
an added option to be settable via SetOption.

Help text for an option is a combination of the string supplied
in the help keyword argument to AddOption and information
collected from the other keyword arguments. Such help is
displayed if the -h command line option is used (but not with
-H). Help for all local options is displayed under the separate
heading Local Options. The options are unsorted - they will
appear in the help text in the order in which the AddOption calls
occur.

Example:

AddOption(
'--prefix',
dest='prefix',
nargs=1,
type='string',
action='store',
metavar='DIR',
help='installation prefix',
)
env = Environment(PREFIX=GetOption('prefix'))

For that example, the following help text would be produced:

Local Options:
--prefix=DIR installation prefix

Help text for local options may be unavailable if the Help
function has been called, see the Help documentation for details.

Note
As an artifact of the internal implementation, the behavior
of options added by AddOption which take option arguments is
undefined if whitespace (rather than an = sign) is used as
the separator on the command line. Users should avoid such
usage; it is recommended to add a note to this effect to
project documentation if the situation is likely to arise. In
addition, if the nargs keyword is used to specify more than
one following option argument (that is, with a value of 2 or
greater), such arguments would necessarily be whitespace
separated, triggering the issue. Developers should not use
AddOption this way. Future versions of SCons will likely
forbid such usage.

AddPostAction(target, action), env.AddPostAction(target, action)
Arranges for the specified action to be performed after the
specified target has been built. action may be an Action object,
or anything that can be converted into an Action object. See the
manpage section "Action Objects" for a complete explanation.

When multiple targets are supplied, the action may be called
multiple times, once after each action that generates one or more
targets in the list.

foo = Program('foo.c')
# remove execute permission from binary:
AddPostAction(foo, Chmod('$TARGET', "a-x"))

AddPreAction(target, action), env.AddPreAction(target, action)
Arranges for the specified action to be performed before the
specified target is built. action may be an Action object, or
anything that can be converted into an Action object. See the
manpage section "Action Objects" for a complete explanation.

When multiple targets are specified, the action(s) may be called
multiple times, once before each action that generates one or
more targets in the list.

Note that if any of the targets are built in multiple steps, the
action will be invoked just before the "final" action that
specifically generates the specified target(s). For example, when
building an executable program from a specified source .c file
via an intermediate object file:

foo = Program('foo.c')
AddPreAction(foo, 'pre_action')

The specified pre_action would be executed before scons calls the
link command that actually generates the executable program
binary foo, not before compiling the foo.c file into an object
file.

Alias(alias, [source, [action]]), env.Alias(alias, [source,
[action]])
Creates an alias target that can be used as a reference to zero
or more other targets, specified by the optional source
parameter. Aliases provide a way to give a shorter or more
descriptive name to specific targets, and to group multiple
targets under a single name. The alias name, or an Alias Node
object, may be used as a dependency of any other target,
including another alias.


alias and source may each be a string or Node object, or a list
of strings or Node objects; if Nodes are used for alias they must
be Alias nodes. If source is omitted, the alias is created but
has no reference; if selected for building this will result in a
"Nothing to be done." message. An empty alias can be used to
define the alias in a visible place in the project; it can later
be appended to in a subsidiary SConscript file with the actual
target(s) to refer to. The optional action parameter specifies an
action or list of actions that will be executed whenever the any
of the alias targets are out-of-date.


Alias can be called for an existing alias, which appends the
alias and/or action arguments to the existing lists for that
alias.

Returns a list of Alias Node objects representing the alias(es),
which exist outside of any physical file system. The alias name
space is separate from the name space for tangible targets; to
avoid confusion do not reuse target names as alias names.

Examples:

Alias('install')
Alias('install', '/usr/bin')
Alias(['install', 'install-lib'], '/usr/local/lib')

env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
env.Alias('install', ['/usr/local/man'])

env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

AllowSubstExceptions([exception, ...])
Specifies the exceptions that will be ignored when expanding
construction variables. By default, any construction variable
expansions that generate a NameError or IndexError exception will
expand to a '' (an empty string) and not cause scons to fail. All
exceptions not in the specified list will generate an error
message and terminate processing.

If AllowSubstExceptions is called multiple times, each call
completely overwrites the previous list of ignored exceptions.
Calling it with no arguments means no exceptions will be ignored.

Example:

# Requires that all construction variable names exist.
# (You may wish to do this if you want to enforce strictly
# that all construction variables must be defined before use.)
AllowSubstExceptions()

# Also allow a string containing a zero-division expansion
# like '${1 / 0}' to evaluate to ''.
AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

AlwaysBuild(target, ...), env.AlwaysBuild(target, ...)
Marks each given target so that it is always assumed to be
out-of-date, and will always be rebuilt if needed. Note, however,
that AlwaysBuild does not add its target(s) to the default target
list, so the targets will only be built if they are specified on
the command line, or are a dependent of a target specified on the
command line--but they will always be built if so specified.
Multiple targets can be passed in to a single call to
AlwaysBuild.

env.Append(key=val, [...])
Appends value(s) intelligently to construction variables in env.
The construction variables and values to add to them are passed
as key=val pairs (Python keyword arguments). env.Append is
designed to allow adding values without having to think about the
data type of an existing construction variable. Regular Python
syntax can also be used to manipulate the construction variable,
but for that you may need to know the types involved, for example
pure Python lets you directly "add" two lists of strings, but
adding a string to a list or a list to a string requires
different syntax - things Append takes care of. Some pre-defined
construction variables do have type expectations based on how
SCons will use them: for example $CPPDEFINES is often a string or
a list of strings, but can also be a list of tuples or a
dictionary; while $LIBEMITTER is expected to be a callable or
list of callables, and $BUILDERS is expected to be a dictionary.
Consult the documentation for the various construction variables
for more details.

The following descriptions apply to both the Append and Prepend
methods, as well as their Unique variants, with the differences
being the insertion point of the added values and whether
duplication is allowed.


val can be almost any type. If env does not have a construction
variable named key, then key is simply stored with a value of
val. Otherwise, val is combined with the existing value, possibly
converting into an appropriate type which can hold the expanded
contents. There are a few special cases to be aware of. Normally,
when two strings are combined, the result is a new string
containing their concatenation (and you are responsible for
supplying any needed separation); however, the contents of
$CPPDEFINES will be post-processed by adding a prefix and/or
suffix to each entry when the command line is produced, so SCons
keeps them separate - appending a string will result in a
separate string entry, not a combined string. For $CPPDEFINES. as
well as $LIBS, and the various *PATH variables, SCons will amend
the variable by supplying the compiler-specific syntax (e.g.
prepending a -D or /D prefix for $CPPDEFINES), so you should omit
this syntax when adding values to these variables. Examples (gcc
syntax shown in the expansion of CPPDEFINES):

env = Environment(CXXFLAGS="-std=c11", CPPDEFINES="RELEASE")
print(f"CXXFLAGS = {env['CXXFLAGS']}, CPPDEFINES = {env['CPPDEFINES']}")
# notice including a leading space in CXXFLAGS addition
env.Append(CXXFLAGS=" -O", CPPDEFINES="EXTRA")
print(f"CXXFLAGS = {env['CXXFLAGS']}, CPPDEFINES = {env['CPPDEFINES']}")
print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

$ scons -Q
CXXFLAGS = -std=c11, CPPDEFINES = RELEASE
CXXFLAGS = -std=c11 -O, CPPDEFINES = deque(['RELEASE', 'EXTRA'])
CPPDEFINES will expand to -DRELEASE -DEXTRA
scons: `.' is up to date.

Because $CPPDEFINES is intended for command-line specification of
C/C++ preprocessor macros, additional syntax is accepted when
adding to it. The preprocessor accepts arguments to predefine a
macro name by itself (-DFOO for most compilers, /DFOO for
Microsoft C++), which gives it an implicit value of 1, or can be
given with a replacement value (-DBAR=TEXT). SCons follows these
rules when adding to $CPPDEFINES:

+o A string is split on spaces, giving an easy way to enter
multiple macros in one addition. Use an = to specify a valued
macro.

+o A tuple is treated as a valued macro. Use the value None if
the macro should not have a value. It is an error to supply
more than two elements in such a tuple.

+o A list is processed in order, adding each item without
further interpretation. In this case, space-separated strings
are not split.

+o A dictionary is processed in order, adding each key-value
pair as a valued macro. Use the value None if the macro
should not have a value.

Examples:

env = Environment(CPPDEFINES="FOO")
print("CPPDEFINES =", env['CPPDEFINES'])
env.Append(CPPDEFINES="BAR=1")
print("CPPDEFINES =", env['CPPDEFINES'])
env.Append(CPPDEFINES=[("OTHER", 2)])
print("CPPDEFINES =", env['CPPDEFINES'])
env.Append(CPPDEFINES={"EXTRA": "arg"})
print("CPPDEFINES =", env['CPPDEFINES'])
print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

$ scons -Q
CPPDEFINES = FOO
CPPDEFINES = deque(['FOO', 'BAR=1'])
CPPDEFINES = deque(['FOO', 'BAR=1', ('OTHER', 2)])
CPPDEFINES = deque(['FOO', 'BAR=1', ('OTHER', 2), ('EXTRA', 'arg')])
CPPDEFINES will expand to -DFOO -DBAR=1 -DOTHER=2 -DEXTRA=arg
scons: `.' is up to date.

Examples of adding multiple macros:

env = Environment()
env.Append(CPPDEFINES=[("ONE", 1), "TWO", ("THREE", )])
print("CPPDEFINES =", env['CPPDEFINES'])
env.Append(CPPDEFINES={"FOUR": 4, "FIVE": None})
print("CPPDEFINES =", env['CPPDEFINES'])
print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

$ scons -Q
CPPDEFINES = [('ONE', 1), 'TWO', ('THREE',)]
CPPDEFINES = deque([('ONE', 1), 'TWO', ('THREE',), ('FOUR', 4), ('FIVE', None)])
CPPDEFINES will expand to -DONE=1 -DTWO -DTHREE -DFOUR=4 -DFIVE
scons: `.' is up to date.


Changed in version 4.5: clarified the use of tuples vs. other
types, handling is now consistent across the four functions.

env = Environment()
env.Append(CPPDEFINES=("MACRO1", "MACRO2"))
print("CPPDEFINES =", env['CPPDEFINES'])
env.Append(CPPDEFINES=[("MACRO3", "MACRO4")])
print("CPPDEFINES =", env['CPPDEFINES'])
print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

$ scons -Q
CPPDEFINES = ('MACRO1', 'MACRO2')
CPPDEFINES = deque(['MACRO1', 'MACRO2', ('MACRO3', 'MACRO4')])
CPPDEFINES will expand to -DMACRO1 -DMACRO2 -DMACRO3=MACRO4
scons: `.' is up to date.

See $CPPDEFINES for more details.

Appending a string val to a dictionary-typed construction
variable enters val as the key in the dictionary, and None as its
value. Using a tuple type to supply a key-value pair only works
for the special case of $CPPDEFINES described above.

Although most combinations of types work without needing to know
the details, some combinations do not make sense and Python
raises an exception.

When using env.Append to modify construction variables which are
path specifications (conventionally, the names of such end in
PATH), it is recommended to add the values as a list of strings,
even if you are only adding a single string. The same goes for
adding library names to $LIBS.

env.Append(CPPPATH=["#/include"])

See also env.AppendUnique, env.Prepend and env.PrependUnique.

env.AppendENVPath(name, newpath, [envname, sep,
delete_existing=False])
Append path elements specified by newpath to the given search
path string or list name in mapping envname in the construction
environment. Supplying envname is optional: the default is the
execution environment $ENV. Optional sep is used as the search
path separator, the default is the platform's separator
(os.pathsep). A path element will only appear once. Any
duplicates in newpath are dropped, keeping the last appearing (to
preserve path order). If delete_existing is False (the default)
any addition duplicating an existing path element is ignored; if
delete_existing is True the existing value will be dropped and
the path element will be added at the end. To help maintain
uniqueness all paths are normalized (using os.path.normpath and
os.path.normcase).

Example:

print('before:', env['ENV']['INCLUDE'])
include_path = '/foo/bar:/foo'
env.AppendENVPath('INCLUDE', include_path)
print('after:', env['ENV']['INCLUDE'])

Yields:

before: /foo:/biz
after: /biz:/foo/bar:/foo

See also env.PrependENVPath.

env.AppendUnique(key=val, [...], [delete_existing=False])
Append values to construction variables in the current
construction environment, maintaining uniqueness. Works like
env.Append, except that values that would become duplicates are
not added. If delete_existing is set to a true value, then for
any duplicate, the existing instance of val is first removed,
then val is appended, having the effect of moving it to the end.

Example:

env.AppendUnique(CCFLAGS='-g', FOO=['foo.yyy'])

See also env.Append, env.Prepend and env.PrependUnique.

Builder(action, [arguments]), env.Builder(action, [arguments])
Creates a Builder object for the specified action. See the
manpage section "Builder Objects" for a complete explanation of
the arguments and behavior.

Note that the env.Builder() form of the invocation will expand
construction variables in any arguments strings, including the
action argument, at the time it is called using the construction
variables in the env construction environment through which
env.Builder was called. The Builder form delays all variable
expansion until after the Builder object is actually called.

CacheDir(cache_dir, custom_class=None), env.CacheDir(cache_dir,
custom_class=None)
Direct scons to maintain a derived-file cache in cache_dir. The
derived files in the cache will be shared among all the builds
specifying the same cache_dir. Specifying a cache_dir of None
disables derived file caching.

Calling the environment method env.CacheDir limits the effect to
targets built through the specified construction environment.
Calling the global function CacheDir sets a global default that
will be used by all targets built through construction
environments that do not set up environment-specific caching by
calling env.CacheDir.

Caching behavior can be configured by passing a specialized cache
class as the optional custom_class parameter. This class must be
a subclass of SCons.CacheDir.CacheDir. SCons will internally
invoke the custom class for performing caching operations. If the
parameter is omitted or set to None, SCons will use the default
SCons.CacheDir.CacheDir class.

When derived-file caching is being used and scons finds a derived
file that needs to be rebuilt, it will first look in the cache to
see if a file with matching build signature exists (indicating
the input file(s) and build action(s) were identical to those for
the current target), and if so, will retrieve the file from the
cache. scons will report Retrieved `file' from cache instead of
the normal build message. If the derived file is not present in
the cache, scons will build it and then place a copy of the built
file in the cache, identified by its build signature, for future
use.

The Retrieved `file' from cache messages are useful for human
consumption, but less useful when comparing log files between
scons runs which will show differences that are noisy and not
actually significant. To disable, use the --cache-show option.
With this option, scons changes printing to always show the
action that would have been used to build the file without
caching.

Derived-file caching may be disabled for any invocation of scons
by giving the --cache-disable command line option; cache updating
may be disabled, leaving cache fetching enabled, by giving the
--cache-readonly option.

If the --cache-force option is used, scons will place a copy of
all derived files into the cache, even if they already existed
and were not built by this invocation. This is useful to populate
a cache the first time a cache_dir is used for a build, or to
bring a cache up to date after a build with cache updating
disabled (--cache-disable or --cache-readonly) has been done.

The NoCache method can be used to disable caching of specific
files. This can be useful if inputs and/or outputs of some tool
are impossible to predict or prohibitively large.

Note that (at this time) SCons provides no facilities for
managing the derived-file cache. It is up to the developer to
arrange for cache pruning, expiry, access control, etc. if
needed.

Clean(targets, files), env.Clean(targets, files)
Set additional files for removal when any of targets are selected
for cleaning (-c command line option). targets and files can
each be a single filename or node, or a list of filenames or
nodes. These can refer to files or directories. Calling this
method repeatedly has an additive effect.

The related NoClean method has higher priority: any target
specified to NoClean will not be cleaned even if also given as a
files parameter to Clean.

Examples:

Clean('foo', ['bar', 'baz'])
Clean('dist', env.Program('hello', 'hello.c'))
Clean(['foo', 'bar'], 'something_else_to_clean')


SCons does not directly track directories as targets - they are
created if needed and not normally removed in clean mode. In this
example, installing the project creates a subdirectory for the
documentation. The Clean call ensures that the subdirectory is
removed if the project is uninstalled.

Clean(docdir, os.path.join(docdir, projectname))

env.Clone([key=val, ...])
Returns an independent copy of a construction environment. If
there are any unrecognized keyword arguments specified, they are
added as construction variables in the copy, overwriting any
existing values for those keywords. See the manpage section
"Construction Environments" for more details.

Example:

env2 = env.Clone()
env3 = env.Clone(CCFLAGS='-g')

A list of tools and a toolpath may be specified, as in the
Environment constructor:

def MyTool(env):
env['FOO'] = 'bar'

env4 = env.Clone(tools=['msvc', MyTool])

The parse_flags keyword argument is also recognized, to allow
merging command-line style arguments into the appropriate
construction variables (see env.MergeFlags).

# create an environment for compiling programs that use wxWidgets
wx_env = env.Clone(parse_flags='!wx-config --cflags --cxxflags')

The variables keyword argument is also recognized, to allow
(re)initializing construction variables from a Variables object.


Changed in version 4.8.0: the variables parameter was added.

Command(target, source, action, [key=val, ...]), env.Command(target,
source, action, [key=val, ...])
Creates an anonymous builder and calls it, thus recording action
to build target from source into the dependency tree. This can be
more convenient for a single special-case build than having to
define and add a new named Builder.

The Command function accepts the source_scanner and
target_scanner keyword arguments which are used to specify custom
scanners for the specified sources or targets. The value must be
a Scanner object. For example, the global DirScanner object can
be used if any of the sources will be directories that must be
scanned on-disk for changes to files that aren't already
specified in other Builder or function calls.

The Command function also accepts the source_factory and
target_factory keyword arguments which are used to specify
factory functions to create SCons Nodes from any sources or
targets specified as strings. If any sources or targets are
already Node objects, they are not further transformed even if a
factory is specified for them. The default for each is the Entry
factory.

These four arguments, if given, are used in the creation of the
Builder. Other Builder-specific keyword arguments are not
recognized as such. See the manpage section "Builder Objects" for
more information about how these arguments work in a Builder.

Any remaining keyword arguments are passed on to the generated
builder when it is called, and behave as described in the manpage
section "Builder Methods", in short: recognized arguments have
their specified meanings, while the rest are used to override any
same-named existing construction variables from the construction
environment.


action can be an external command, specified as a string, or a
callable Python object; see the manpage section "Action Objects"
for more complete information. Also note that a string specifying
an external command may be preceded by an at-sign (@) to suppress
printing the command in question, or by a hyphen (-) to ignore
the exit status of the external command.

Examples:

env.Command(
target='foo.out',
source='foo.in',
action="$FOO_BUILD < $SOURCES > $TARGET"
)

env.Command(
target='bar.out',
source='bar.in',
action=["rm -f $TARGET", "$BAR_BUILD < $SOURCES > $TARGET"],
ENV={'PATH': '/usr/local/bin/'},
)


import os
def rename(env, target, source):
os.rename('.tmp', str(target[0]))


env.Command(
target='baz.out',
source='baz.in',
action=["$BAZ_BUILD < $SOURCES > .tmp", rename],
)

Note that the Command function will usually assume, by default,
that the specified targets and/or sources are Files, if no other
part of the configuration identifies what type of entries they
are. If necessary, you can explicitly specify that targets or
source nodes should be treated as directories by using the Dir or
env.Dir functions.

Examples:

env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')

env['DISTDIR'] = 'destination/directory'
env.Command(env.Dir('$DISTDIR')), None, make_distdir)

Also note that SCons will usually automatically create any
directory necessary to hold a target file, so you normally don't
need to create directories by hand.

Configure(env, [custom_tests, conf_dir, log_file, config_h]),
env.Configure([custom_tests, conf_dir, log_file, config_h])
Creates a Configure object for integrated functionality similar
to GNU autoconf. See the manpage section "Configure Contexts" for
a complete explanation of the arguments and behavior.

DebugOptions([json])
Allows setting options for SCons debug options. Currently, the
only supported value is json which sets the path to the JSON file
created when --debug=json is set.

DebugOptions(json='#/build/output/scons_stats.json')

New in version 4.6.0.

Decider(function), env.Decider(function)
Specifies that all up-to-date decisions for targets built through
this construction environment will be handled by function.
function can be the name of a function or one of the following
strings that specify a predefined decider function:

"content"
Specifies that a target shall be considered out-of-date and
rebuilt if the dependency's content has changed since the
last time the target was built, as determined by performing a
checksum on the dependency's contents using the selected hash
function, and comparing it to the checksum recorded the last
time the target was built. content is the default decider.


Changed in version 4.1: The decider was renamed to content
since the hash function is now selectable. The former name,
MD5, can still be used as a synonym, but is deprecated.

"content-timestamp"
Specifies that a target shall be considered out-of-date and
rebuilt if the dependency's content has changed since the
last time the target was built, except that dependencies with
a timestamp that matches the last time the target was rebuilt
will be assumed to be up-to-date and not rebuilt. This
provides behavior very similar to the content behavior of
always checksumming file contents, with an optimization of
not checking the contents of files whose timestamps haven't
changed. The drawback is that SCons will not detect if a
file's content has changed but its timestamp is the same, as
might happen in an automated script that runs a build,
updates a file, and runs the build again, all within a single
second.


Changed in version 4.1: The decider was renamed to
content-timestamp since the hash function is now selectable.
The former name, MD5-timestamp, can still be used as a
synonym, but is deprecated.

"timestamp-newer"
Specifies that a target shall be considered out-of-date and
rebuilt if the dependency's timestamp is newer than the
target file's timestamp. This is the behavior of the classic
Make utility, and make can be used a synonym for
timestamp-newer.

"timestamp-match"
Specifies that a target shall be considered out-of-date and
rebuilt if the dependency's timestamp is different than the
timestamp recorded the last time the target was built. This
provides behavior very similar to the classic Make utility
(in particular, files are not opened up so that their
contents can be checksummed) except that the target will also
be rebuilt if a dependency file has been restored to a
version with an earlier timestamp, such as can happen when
restoring files from backup archives.

Examples:

# Use exact timestamp matches by default.
Decider('timestamp-match')

# Use hash content signatures for any targets built
# with the attached construction environment.
env.Decider('content')

In addition to the above already-available functions, the
function argument may be a Python function you supply. Such a
function must accept the following four arguments:

dependency
The Node (file) which should cause the target to be rebuilt
if it has "changed" since the last time target was built.

target
The Node (file) being built. In the normal case, this is what
should get rebuilt if the dependency has "changed."

prev_ni
Stored information about the state of the dependency the last
time the target was built. This can be consulted to match
various file characteristics such as the timestamp, size, or
content signature.

repo_node
If set, use this Node instead of the one specified by
dependency to determine if the dependency has changed. This
argument is optional so should be written as a default
argument (typically it would be written as repo_node=None). A
caller will normally only set this if the target only exists
in a Repository.

The function should return a value which evaluates True if the
dependency has "changed" since the last time the target was built
(indicating that the target should be rebuilt), and a value which
evaluates False otherwise (indicating that the target should not
be rebuilt). Note that the decision can be made using whatever
criteria are appropriate. Ignoring some or all of the function
arguments is perfectly normal.

Example:

def my_decider(dependency, target, prev_ni, repo_node=None):
return not os.path.exists(str(target))

env.Decider(my_decider)

Default(target[, ...]), env.Default(target[, ...])
Specify default targets to the SCons target selection mechanism.
Any call to Default will cause SCons to use the defined default
target list instead of its built-in algorithm for determining
default targets (see the manpage section "Target Selection").


target may be one or more strings, a list of strings, a NodeList
as returned by a Builder, or None. A string target may be the
name of a file or directory, or a target previously defined by a
call to Alias (defining the alias later will still create the
alias, but it will not be recognized as a default). Calls to
Default are additive. A target of None will clear any existing
default target list; subsequent calls to Default will add to the
(now empty) default target list like normal.

Both forms of this call affect the same global list of default
targets; the construction environment method applies construction
variable expansion to the targets.

The current list of targets added using Default is available in
the DEFAULT_TARGETS list (see below).

Examples:

Default('foo', 'bar', 'baz')
env.Default(['a', 'b', 'c'])
hello = env.Program('hello', 'hello.c')
env.Default(hello)

DefaultEnvironment([key=value, ...])
Instantiates and returns the global construction environment
object. The Default Environment is used internally by SCons when
executing a global function or the global form of a Builder
method that requires access to a construction environment.

On the first call, arguments are interpreted as for the
Environment function. The Default Environment is a singleton;
subsequent calls to DefaultEnvironment return the
already-constructed object, and any keyword arguments are
silently ignored.

The Default Environment can be modified after instantiation,
similar to other construction environments, although some
construction environment methods may be unavailable. Modifying
the Default Environment has no effect on any other construction
environment, either existing or newly constructed.

It is not necessary to explicitly call DefaultEnvironment. SCons
instantiates the default environment automatically when the build
phase begins, if has not already been done. However, calling it
explicitly provides the opportunity to affect and examine its
contents. Instantiation occurs even if nothing in the build
system appears to use it, due to internal uses.

If the project SConscript files do not use global functions or
Builders, a small performance gain may be achieved by calling
DefaultEnvironment with an empty tools list
(DefaultEnvironment(tools=[])). This avoids the tool
initialization cost for the Default Environment, which is mainly
of interest in the test suite where scons is launched repeatedly
in a short time period.

Depends(target, dependency), env.Depends(target, dependency)
Specifies an explicit dependency; the target will be rebuilt
whenever the dependency has changed. Both the specified target
and dependency can be a string (usually the path name of a file
or directory) or Node objects, or a list of strings or Node
objects (such as returned by a Builder call). This should only be
necessary for cases where the dependency is not caught by a
Scanner for the file.

Example:

env.Depends('foo', 'other-input-file-for-foo')

mylib = env.Library('mylib.c')
installed_lib = env.Install('lib', mylib)
bar = env.Program('bar.c')

# Arrange for the library to be copied into the installation
# directory before trying to build the "bar" program.
# (Note that this is for example only. A "real" library
# dependency would normally be configured through the $LIBS
# and $LIBPATH variables, not using an env.Depends() call.)

env.Depends(bar, installed_lib)

env.Detect(progs)
Find an executable from one or more choices: progs may be a
string or a list of strings. Returns the first value from progs
that was found, or None. Executable is searched by checking the
paths in the execution environment (env['ENV']['PATH']). On
Windows systems, additionally applies the filename suffixes found
in the execution environment (env['ENV']['PATHEXT']) but will not
include any such extension in the return value. env.Detect is a
wrapper around env.WhereIs.

env.Dictionary([var, ...], [as_dict=])
Return an object containing construction variables from env. If
var is omitted, all the construction variables with their values
are returned in a dict. If var is specified, and as_dict is true,
the specified construction variables are returned in a dict;
otherwise (the default, for backwards compatibility), values only
are returned, as a scalar if one var is given, or as a list if
multiples.

Example:

cvars = env.Dictionary()
cc_values = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')


Note
The object returned by env.Dictionary should be treated as a
read-only view into the construction variables. Some
construction variables require special internal handling, and
modifying them through the env.Dictionary object can bypass
that handling and cause data inconsistencies. The primary use
of env.Dictionary is for diagnostic purposes - it is used
widely by test cases specifically because it bypasses the
special handling so that behavior can be verified.
Changed in 4.9.0: as_dict added.

Dir(name, [directory]), env.Dir(name, [directory])
Returns Directory Node(s). A Directory Node is an object that
represents a directory. name can be a relative or absolute path
or a list of such paths. directory is an optional directory that
will be used as the parent directory. If no directory is
specified, the current script's directory is used as the parent.

If name is a single pathname, the corresponding node is returned.
If name is a list, SCons returns a list of nodes. Construction
variables are expanded in name.

Directory Nodes can be used anywhere you would supply a string as
a directory name to a Builder method or function. Directory Nodes
have attributes and methods that are useful in many situations;
see manpage section "Filesystem Nodes" for more information.

env.Dump([var, ...], [format=TYPE])
Serialize construction variables from env to a string. If var is
omitted, all the construction variables are serialized. If one or
more var values are supplied, only those variables and their
values are serialized.

The optional format string selects the serialization format:

pretty
Returns a pretty-printed representation of the construction
variables - the result will look like a Python dict (this is
the default).

json
Returns a JSON-formatted representation of the variables. The
variables will be presented as a JSON object literal, the
JSON equivalent of a Python dict..


Changed in 4.9.0: More than one key can be specified. The
returned string always looks like a dict (or equivalent in other
formats); previously a single key serialized only the value, not
the key with the value.

Examples: this SConstruct

env = Environment()
print(env.Dump('CCCOM'))
print(env.Dump('CC', 'CCFLAGS', format='json'))

will print something like:

{'CCCOM': '$CC -o $TARGET -c $CFLAGS $CCFLAGS $_CCCOMCOM $SOURCES'}
{
"CC": "gcc",
"CCFLAGS": []
}

While this SConstruct:

env = Environment()
print(env.Dump())

will print something like:

{ 'AR': 'ar',
'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET',
'ARFLAGS': ['r'],
'AS': 'as',
'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
'ASFLAGS': [],
...

EnsurePythonVersion(major, minor)
Ensure that the Python version is at least major.minor. This
function will print out an error message and exit SCons with a
non-zero exit code if the actual Python version is not late
enough.

Example:

EnsurePythonVersion(2,2)

EnsureSConsVersion(major, minor, [revision])
Ensure that the SCons version is at least major.minor, or
major.minor.revision. if revision is specified. This function
will print out an error message and exit SCons with a non-zero
exit code if the actual SCons version is not late enough.

Examples:

EnsureSConsVersion(0,14)

EnsureSConsVersion(0,96,90)

Environment([key=value, ...]), env.Environment([key=value, ...])
Return a new construction environment initialized with the
specified key=value pairs. The keyword arguments parse_flags,
platform, toolpath, tools and variables are specially recognized
and do not lead to construction variable creation. See the
manpage section "Construction Environments" for more details.

Execute(action, [actionargs ...]), env.Execute(action, [actionargs
...])
Executes an Action. action may be an Action object or it may be
a command-line string, list of commands, or executable Python
function, each of which will first be converted into an Action
object and then executed. Any additional arguments to Execute are
passed on to the Action factory function which actually creates
the Action object (see the manpage section Action Objects for a
description). Example:

Execute(Copy('file.out', 'file.in'))

Execute performs its action immediately, as part of the
SConscript-reading phase. There are no sources or targets
declared in an Execute call, so any objects it manipulates will
not be tracked as part of the SCons dependency graph. In the
example above, neither file.out nor file.in will be tracked
objects.


Execute returns the exit value of the command or return value of
the Python function. scons prints an error message if the
executed action fails (exits with or returns a non-zero value),
however it does not, automatically terminate the build for such a
failure. If you want the build to stop in response to a failed
Execute call, you must explicitly check for a non-zero return
value:

if Execute("mkdir sub/dir/ectory"):
# The mkdir failed, don't try to build.
Exit(1)

Exit([value])
This tells scons to exit immediately with the specified value. A
default exit value of 0 (zero) is used if no value is specified.

Export([vars...], [key=value...]), env.Export([vars...],
[key=value...])
Exports variables for sharing with other SConscript files. The
variables are added to a global collection where they can be
imported by other SConscript files. vars may be one or more
strings, or a list of strings. If any string contains whitespace,
it is split automatically into individual strings. Each string
must match the name of a variable that is in scope during
evaluation of the current SConscript file, or an exception is
raised.

A vars argument may also be a dictionary or individual keyword
arguments; in accordance with Python syntax rules, keyword
arguments must come after any non-keyword arguments. The
dictionary/keyword form can be used to map the local name of a
variable to a different name to be used for imports. See the
Examples for an illustration of the syntax.


Export calls are cumulative. Specifying a previously exported
variable will replace the previous value in the collection. Both
local variables and global variables can be exported.

To use an exported variable, an SConscript must call Import to
bring it into its own scope. Importing creates an additional
reference to the object that was originally exported, so if that
object is mutable, changes made will be visible to other users of
that object.

Examples:

env = Environment()
# Make env available for all SConscript files to Import().
Export("env")

package = 'my_name'
# Make env and package available for all SConscript files:.
Export("env", "package")

# Make env and package available for all SConscript files:
Export(["env", "package"])

# Make env available using the name debug:
Export(debug=env)

# Make env available using the name debug:
Export({"debug": env})

Note that the SConscript function also supports an exports
argument that allows exporting one or more variables to the
SConscript files invoked by that call (only). See the description
of that function for details.

File(name, [directory]), env.File(name, [directory])
Returns File Node(s). A File Node is an object that represents a
file. name can be a relative or absolute path or a list of such
paths. directory is an optional directory that will be used as
the parent directory. If no directory is specified, the current
script's directory is used as the parent.

If name is a single pathname, the corresponding node is returned.
If name is a list, SCons returns a list of nodes. Construction
variables are expanded in name.

File Nodes can be used anywhere you would supply a string as a
file name to a Builder method or function. File Nodes have
attributes and methods that are useful in many situations; see
manpage section "Filesystem Nodes" for more information.

FindFile(file, dirs), env.FindFile(file, dirs)
Search for file in the path specified by dirs. dirs may be a
list of directory names or a single directory name. In addition
to searching for files that exist in the filesystem, this
function also searches for derived files that have not yet been
built.

Example:

foo = env.FindFile('foo', ['dir1', 'dir2'])

FindInstalledFiles(), env.FindInstalledFiles()
Returns the list of targets set up by the Install or InstallAs
builders.

This function serves as a convenient method to select the
contents of a binary package.

Example:

Install('/bin', ['executable_a', 'executable_b'])

# will return the file node list
# ['/bin/executable_a', '/bin/executable_b']
FindInstalledFiles()

Install('/lib', ['some_library'])

# will return the file node list
# ['/bin/executable_a', '/bin/executable_b', '/lib/some_library']
FindInstalledFiles()

FindPathDirs(variable)
Returns a function (actually a callable Python object) intended
to be used as the path_function of a Scanner object. The returned
object will look up the specified variable in a construction
environment and treat the construction variable's value as a list
of directory paths that should be searched (like $CPPPATH,
$LIBPATH, etc.).

Note that use of FindPathDirs is generally preferable to writing
your own path_function for the following reasons: 1) The returned
list will contain all appropriate directories found in source
trees (when VariantDir is used) or in code repositories (when
Repository or the -Y option are used). 2) scons will identify
expansions of variable that evaluate to the same list of
directories as, in fact, the same list, and avoid re-scanning the
directories for files, when possible.

Example:

def my_scan(node, env, path, arg):
# Code to scan file contents goes here...
return include_files

scanner = Scanner(name = 'myscanner',
function = my_scan,
path_function = FindPathDirs('MYPATH'))

FindSourceFiles(node='"."'), env.FindSourceFiles(node='"."')
Returns the list of nodes which serve as the source of the built
files. It does so by inspecting the dependency tree starting at
the optional argument node which defaults to the '"."'-node. It
will then return all leaves of node. These are all children which
have no further children.

This function is a convenient method to select the contents of a
Source Package.

Example:

Program('src/main_a.c')
Program('src/main_b.c')
Program('main_c.c')

# returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
FindSourceFiles()

# returns ['src/main_b.c', 'src/main_a.c' ]
FindSourceFiles('src')

As you can see, build support files (SConstruct in the above
example) will also be returned by this function.

Flatten(sequence), env.Flatten(sequence)
Takes a sequence (that is, a Python list or tuple) that may
contain nested sequences and returns a flattened list containing
all of the individual elements in any sequence. This can be
helpful for collecting the lists returned by calls to Builders;
other Builders will automatically flatten lists specified as
input, but direct Python manipulation of these lists does not.

Examples:

foo = Object('foo.c')
bar = Object('bar.c')

# Because `foo' and `bar' are lists returned by the Object() Builder,
# `objects' will be a list containing nested lists:
objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']

# Passing such a list to another Builder is all right because
# the Builder will flatten the list automatically:
Program(source = objects)

# If you need to manipulate the list directly using Python, you need to
# call Flatten() yourself, or otherwise handle nested lists:
for object in Flatten(objects):
print(str(object))

GetBuildFailures()
Returns a list of exceptions for the actions that failed while
attempting to build targets. Each element in the returned list is
a BuildError object with the following attributes that record
various aspects of the build failure:


.node The node that was being built when the build failure
occurred.


.status The numeric exit status returned by the command or Python
function that failed when trying to build the specified Node.


.errstr The SCons error string describing the build failure.
(This is often a generic message like "Error 2" to indicate that
an executed command exited with a status of 2.)


.filename The name of the file or directory that actually caused
the failure. This may be different from the .node attribute. For
example, if an attempt to build a target named sub/dir/target
fails because the sub/dir directory could not be created, then
the .node attribute will be sub/dir/target but the .filename
attribute will be sub/dir.


.executor The SCons Executor object for the target Node being
built. This can be used to retrieve the construction environment
used for the failed action.


.action The actual SCons Action object that failed. This will be
one specific action out of the possible list of actions that
would have been executed to build the target.


.command The actual expanded command that was executed and
failed, after expansion of $TARGET, $SOURCE, and other
construction variables.

Note that the GetBuildFailures function will always return an
empty list until any build failure has occurred, which means that
GetBuildFailures will always return an empty list while the
SConscript files are being read. Its primary intended use is for
functions that will be executed before SCons exits by passing
them to the standard Python atexit.register() function. Example:

import atexit

def print_build_failures():
from SCons.Script import GetBuildFailures
for bf in GetBuildFailures():
print("%s failed: %s" % (bf.node, bf.errstr))

atexit.register(print_build_failures)

GetBuildPath(file, [...]), env.GetBuildPath(file, [...])
Returns the scons path name (or names) for the specified file (or
files). The specified file or files may be scons Nodes or strings
representing path names.

GetLaunchDir()
Returns the absolute path name of the directory from which scons
was initially invoked. This can be useful when using the -u, -U
or -D options, which internally change to the directory in which
the SConstruct file is found.

GetOption(name), env.GetOption(name)
Query the value of settable options which may have been set on
the command line, via option defaults, or by using the SetOption
function. The value of the option is returned in a type matching
how the option was declared - see the documentation of the
corresponding command line option for information about each
specific option.


name can be an entry from the following table, which shows the
corresponding command line arguments that could affect the value.
name can be also be the destination variable name from a
project-specific option added using the AddOption function, as
long as that addition has been processed prior to the GetOption
call in the SConscript files.

+------------------------+---------------------------+--------------------+
|Query name | Command-line options | Notes |
+------------------------+---------------------------+--------------------+
|cache_debug | --cache-debug | |
+------------------------+---------------------------+--------------------+
|cache_disable | --cache-disable, | |
| | --no-cache | |
+------------------------+---------------------------+--------------------+
|cache_force | --cache-force, | |
| | --cache-populate | |
+------------------------+---------------------------+--------------------+
|cache_readonly | --cache-readonly | |
+------------------------+---------------------------+--------------------+
|cache_show | --cache-show | |
+------------------------+---------------------------+--------------------+
|clean | -c, --clean, | |
| | --remove | |
+------------------------+---------------------------+--------------------+
|climb_up | -D -U -u | |
| | --up --search_up | |
+------------------------+---------------------------+--------------------+
|config | --config | |
+------------------------+---------------------------+--------------------+
|debug | --debug | |
+------------------------+---------------------------+--------------------+
|directory | -C, --directory | |
+------------------------+---------------------------+--------------------+
|diskcheck | --diskcheck | |
+------------------------+---------------------------+--------------------+
|duplicate | --duplicate | |
+------------------------+---------------------------+--------------------+
|enable_virtualenv | --enable-virtualenv | |
+------------------------+---------------------------+--------------------+
|experimental | --experimental | since 4.2 |
+------------------------+---------------------------+--------------------+
|file | -f, --file, | |
| | --makefile, | |
| | --sconstruct | |
+------------------------+---------------------------+--------------------+
|hash_format | --hash-format | since 4.2 |
+------------------------+---------------------------+--------------------+
|help | -h, --help | |
+------------------------+---------------------------+--------------------+
|ignore_errors | -i, --ignore-errors | |
+------------------------+---------------------------+--------------------+
|ignore_virtualenv | --ignore-virtualenv | |
+------------------------+---------------------------+--------------------+
|implicit_cache | --implicit-cache | |
+------------------------+---------------------------+--------------------+
|implicit_deps_changed | --implicit-deps-changed | |
+------------------------+---------------------------+--------------------+
|implicit_deps_unchanged | --implicit-deps-unchanged | |
+------------------------+---------------------------+--------------------+
|include_dir | -I, --include-dir | |
+------------------------+---------------------------+--------------------+
|install_sandbox | --install-sandbox | Available only if |
| | | the install tool |
| | | has been called |
+------------------------+---------------------------+--------------------+
|keep_going | -k, --keep-going | |
+------------------------+---------------------------+--------------------+
|max_drift | --max-drift | |
+------------------------+---------------------------+--------------------+
|md5_chunksize | --hash-chunksize, | --hash-chunksize |
| | --md5-chunksize | since 4.2 |
+------------------------+---------------------------+--------------------+
|no_exec | -n, --no-exec, | |
| | --just-print, | |
| | --dry-run, --recon | |
+------------------------+---------------------------+--------------------+
|no_progress | -Q | |
+------------------------+---------------------------+--------------------+
|num_jobs | -j, --jobs | |
+------------------------+---------------------------+--------------------+
|package_type | --package-type | Available only if |
| | | the packaging tool |
| | | has been called |
+------------------------+---------------------------+--------------------+
|profile_file | --profile | |
+------------------------+---------------------------+--------------------+
|question | -q, --question | |
+------------------------+---------------------------+--------------------+
|random | --random | |
+------------------------+---------------------------+--------------------+
|repository | -Y, --repository, | |
| | --srcdir | |
+------------------------+---------------------------+--------------------+
|silent | -s, --silent, | |
| | --quiet | |
+------------------------+---------------------------+--------------------+
|site_dir | --site-dir, --no-site-dir | |
+------------------------+---------------------------+--------------------+
|stack_size | --stack-size | |
+------------------------+---------------------------+--------------------+
|taskmastertrace_file | --taskmastertrace | |
+------------------------+---------------------------+--------------------+
|tree_printers | --tree | |
+------------------------+---------------------------+--------------------+
|warn | --warn, --warning | |
+------------------------+---------------------------+--------------------+

GetSConsVersion()
Returns the current SCons version in the form of a Tuple[int,
int, int], representing the major, minor, and revision values
respectively. Added in 4.8.0.

Glob(pattern, [ondisk=True, source=False, strings=False,
exclude=None]), env.Glob(pattern, [ondisk=True, source=False,
strings=False, exclude=None])
Returns a possibly empty list of Nodes (or strings) that match
pathname specification pattern. pattern can be absolute,
top-relative, or (most commonly) relative to the directory of the
current SConscript file. Glob matches both files stored on disk
and Nodes which SCons already knows about, even if any
corresponding file is not currently stored on disk. The
environment method form (env.Glob) performs string substitution
on pattern and returns whatever matches the resulting expanded
pattern. The results are sorted, unlike for the similar Python
glob.glob function, to ensure build order will be stable.


pattern can contain POSIX-style shell metacharacters for
matching:

+--------+---------------------------+
|Pattern | Meaning |
+--------+---------------------------+
|* | matches everything |
+--------+---------------------------+
|? | matches any single |
| | character |
+--------+---------------------------+
|[seq] | matches any character in |
| | seq (can be a list |
| | or a range). |
+--------+---------------------------+
|[!seq] | matches any character not |
| | in seq |
+--------+---------------------------+
For a literal match, wrap the metacharacter in brackets to escape
the normal behavior. For example, '[?]' matches the character
'?'.

Filenames starting with a dot are specially handled - they can
only be matched by patterns that start with a dot (or have a dot
immediately following a pathname separator character, or slash),
they are not not matched by the metacharacters. Metacharacter
matches also do not span directory separators.


Glob understands repositories (see the Repository function) and
source directories (see the VariantDir function) and returns a
Node (or string, if so configured) match in the local
(SConscript) directory if a matching Node is found anywhere in a
corresponding repository or source directory.

If the optional ondisk argument evaluates false, the search for
matches on disk is disabled, and only matches from
already-configured File or Dir Nodes are returned. The default is
to return Nodes for matches on disk as well.

If the optional source argument evaluates true, and the local
directory is a variant directory, then Glob returns Nodes from
the corresponding source directory, rather than the local
directory.

If the optional strings argument evaluates true, Glob returns
matches as strings, rather than Nodes. The returned strings will
be relative to the local (SConscript) directory. (Note that while
this may make it easier to perform arbitrary manipulation of file
names, it loses the context SCons would have in the Node, so if
the returned strings are passed to a different SConscript file,
any Node translation there will be relative to that SConscript
directory, not to the original SConscript directory.)

The optional exclude argument may be set to a pattern or a list
of patterns describing files or directories to filter out of the
match list. Elements matching a least one specified pattern will
be excluded. These patterns use the same syntax as for pattern.

Examples:

Program("foo", Glob("*.c"))
Zip("/tmp/everything", Glob(".??*") + Glob("*"))
sources = Glob("*.cpp", exclude=["os_*_specific_*.cpp"]) \
+ Glob("os_%s_specific_*.cpp" % currentOS)

Help(text, append=False, local_only=False), env.Help(text,
append=False, local_only=False)
Adds text to the help message shown when scons is called with the
-h or --help argument.

On the first call to Help, if append is False (the default), any
existing help text is discarded. The default help text is the
help for the scons command itself plus help collected from any
project-local AddOption calls. This is the help printed if Help
has never been called. If append is True, text is appended to the
existing help text. If local_only is also True (the default is
False), the project-local help from AddOption calls is preserved
in the help message but the scons command help is not.

Subsequent calls to Help ignore the keyword arguments append and
local_only and always append to the existing help text.


Changed in 4.6.0: added local_only.

Ignore(target, dependency), env.Ignore(target, dependency)
Ignores dependency when deciding if target needs to be rebuilt.
target and dependency can each be a single filename or Node or a
list of filenames or Nodes.


Ignore can also be used to remove a target from the default build
by specifying the directory the target will be built in as target
and the file you want to skip selecting for building as
dependency. Note that this only removes the target from the
default target selection algorithm: if it is a dependency of
another object being built SCons still builds it normally. See
the third and forth examples below.

Examples:

env.Ignore('foo', 'foo.c')
env.Ignore('bar', ['bar1.h', 'bar2.h'])
env.Ignore('.', 'foobar.obj')
env.Ignore('bar', 'bar/foobar.obj')

Import(vars...), env.Import(vars...)
Imports variables into the scope of the current SConscript file.
vars must be strings representing names of variables which have
been previously exported either by the Export function or by the
exports argument to the SConscript function. Variables exported
by the SConscript call take precedence. Multiple variable names
can be passed to Import as separate arguments, as a list of
strings, or as words in a space-separated string. The wildcard
"*" can be used to import all available variables.

If the imported variable is mutable, changes made locally will be
reflected in the object the variable is bound to. This allows
subsidiary SConscript files to contribute to building up, for
example, a construction environment.

Examples:

Import("env")
Import("env", "variable")
Import(["env", "variable"])
Import("*")

Literal(string), env.Literal(string)
The specified string will be preserved as-is and not have
construction variables expanded.

Local(targets), env.Local(targets)
The specified targets will have copies made in the local tree,
even if an already up-to-date copy exists in a repository.
Returns a list of the target Node or Nodes.

env.MergeFlags(arg, [unique])
Merges values from arg into construction variables in env. If arg
is a dictionary, each key-value pair represents a construction
variable name and the corresponding flags to merge. If arg is not
a dictionary, MergeFlags attempts to convert it to one before the
values are merged. env.ParseFlags is used for this, so values to
be converted are subject to the same limitations: ParseFlags has
knowledge of which construction variables certain flags should go
to, but not all; and only for GCC and compatible compiler chains.
arg must be a single object, so to pass multiple strings, enclose
them in a list.

If unique is true (the default), duplicate values are not
retained. In case of duplication, any construction variable names
that end in PATH keep the left-most value so the path search
order is not altered. All other construction variables keep the
right-most value. If unique is false, values are appended even if
they are duplicates.

Examples:

# Add an optimization flag to $CCFLAGS.
env.MergeFlags({'CCFLAGS': '-O3'})

# Combine the flags returned from running pkg-config with an optimization
# flag and merge the result into the construction variables.
env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])

# Combine an optimization flag with the flags returned from running pkg-config
# for two distinct packages and merge into the construction variables.
env.MergeFlags(
[
'-O3',
'!pkg-config gtk+-2.0 --cflags --libs',
'!pkg-config libpng12 --cflags --libs',
]
)

NoCache(target, ...), env.NoCache(target, ...)
Specifies a list of files which should not be cached whenever the
CacheDir method has been activated. The specified targets may be
a list or an individual target.

Multiple files should be specified either as separate arguments
to the NoCache method, or as a list. NoCache will also accept
the return value of any of the construction environment Builder
methods.

Calling NoCache on directories and other non-File Node types has
no effect because only File Nodes are cached.

Examples:

NoCache('foo.elf')
NoCache(env.Program('hello', 'hello.c'))

NoClean(targets, ...), env.NoClean(targets, ...)
Specifies files or directories which should not be removed
whenever a specified target (or its dependencies) is selected and
clean mode is active (-c command line option). targets may be
one or more file or directory names or nodes, and/or lists of
names or nodes. NoClean can be called multiple times.

Calling NoClean for a target overrides calling Clean for the same
target, so any targets passed to both functions will not be
removed in clean mode.

Examples:

NoClean('foo.elf')
NoClean(env.Program('hello', 'hello.c'))

env.ParseConfig(command, [function, unique])
Updates the current construction environment with the values
extracted from the output of running external command, by passing
it to a helper function. command may be a string or a list of
strings representing the command and its arguments. If function
is omitted or None, env.MergeFlags is used. By default, duplicate
values are not added to any construction variables; you can
specify unique=False to allow duplicate values to be added.


command is executed using the SCons execution environment (that
is, the construction variable $ENV in the current construction
environment). If command needs additional information to operate
properly, that needs to be set in the execution environment. For
example, pkg-config may need a custom value set in the
PKG_CONFIG_PATH environment variable.


env.MergeFlags needs to understand the output produced by command
in order to distribute it to appropriate construction variables.
env.MergeFlags uses a separate function to do that processing -
see env.ParseFlags for the details, including a table of options
and corresponding construction variables. To provide alternative
processing of the output of command, you can supply a custom
function, which must accept three arguments: the construction
environment to modify, a string argument containing the output
from running command, and the optional unique flag.

ParseDepends(filename, [must_exist, only_one]),
env.ParseDepends(filename, [must_exist, only_one])
Parses the contents of filename as a list of dependencies in the
style of Make or mkdep, and explicitly establishes all of the
listed dependencies.

By default, it is not an error if filename does not exist. The
optional must_exist argument may be set to True to have SCons
raise an exception if the file does not exist, or is otherwise
inaccessible.

The optional only_one argument may be set to True to have SCons
raise an exception if the file contains dependency information
for more than one target. This can provide a small sanity check
for files intended to be generated by, for example, the gcc -M
flag, which should typically only write dependency information
for one output file into a corresponding .d file.


filename and all of the files listed therein will be interpreted
relative to the directory of the SConscript file which calls the
ParseDepends function.

env.ParseFlags(flags, ...)
Parses one or more strings containing typical command-line flags
for GCC-style tool chains and returns a dictionary with the flag
values separated into the appropriate SCons construction
variables. Intended as a companion to the env.MergeFlags method,
but allows for the values in the returned dictionary to be
modified, if necessary, before merging them into the construction
environment. (Note that env.MergeFlags will call this method if
its argument is not a dictionary, so it is usually not necessary
to call env.ParseFlags directly unless you want to manipulate the
values.)

If the first character in any string is an exclamation mark (!),
the rest of the string is executed as a command, and the output
from the command is parsed as GCC tool chain command-line flags
and added to the resulting dictionary. This can be used to call a
*-config command typical of the POSIX programming environment
(for example, pkg-config). Note that such a command is executed
using the SCons execution environment; if the command needs
additional information, that information needs to be explicitly
provided. See ParseConfig for more details.

Flag values are translated according to the prefix found, and
added to the following construction variables:

-arch CCFLAGS, LINKFLAGS
-D CPPDEFINES
-framework FRAMEWORKS
-frameworkdir= FRAMEWORKPATH
-fmerge-all-constants CCFLAGS, LINKFLAGS
-fopenmp CCFLAGS, LINKFLAGS
-fsanitize CCFLAGS, LINKFLAGS
-include CCFLAGS
-imacros CCFLAGS
-isysroot CCFLAGS, LINKFLAGS
-isystem CCFLAGS
-iquote CCFLAGS
-idirafter CCFLAGS
-I CPPPATH
-l LIBS
-L LIBPATH
-mno-cygwin CCFLAGS, LINKFLAGS
-mwindows LINKFLAGS
-openmp CCFLAGS, LINKFLAGS
-pthread CCFLAGS, LINKFLAGS
-std= CFLAGS
-stdlib= CXXFLAGS
-Wa, ASFLAGS, CCFLAGS
-Wl,-rpath= RPATH
-Wl,-R, RPATH
-Wl,-R RPATH
-Wl, LINKFLAGS
-Wp, CPPFLAGS
- CCFLAGS
+ CCFLAGS, LINKFLAGS

Any other strings not associated with options are assumed to be
the names of libraries and added to the $LIBS construction
variable.

Examples (all of which produce the same result):

dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')

Platform(plat), env.Platform(plat)
When called as a global function, returns a callable platform
object selected by plat (defaults to the detected platform for
the current system) that can be used to initialize a construction
environment by passing it as the platform keyword argument to the
Environment function.

Example:

env = Environment(platform=Platform('win32'))

When called as a method of an environment, calls the platform
object indicated by plat to update that environment.

env.Platform('posix')

See the manpage section "Construction Environments" for more
details.

Precious(target, ...), env.Precious(target, ...)
Marks target as precious so it is not deleted before it is
rebuilt. Normally SCons deletes a target before building it.
Multiple targets can be passed in a single call, and may be
strings and/or nodes. Returns a list of the affected target
nodes.

env.Prepend(key=val, [...])
Prepend values to construction variables in the current
construction environment, works like env.Append (see for
details), except that values are added to the front, rather than
the end, of any existing value of the construction variable

Example:

env.Prepend(CCFLAGS='-g ', FOO=['foo.yyy'])

See also env.Append, env.AppendUnique and env.PrependUnique.

env.PrependENVPath(name, newpath, [envname, sep,
delete_existing=True])
Prepend path elements specified by newpath to the given search
path string or list name in mapping envname in the construction
environment. Supplying envname is optional: the default is the
execution environment $ENV. Optional sep is used as the search
path separator, the default is the platform's separator
(os.pathsep). A path element will only appear once. Any
duplicates in newpath are dropped, keeping the first appearing
(to preserve path order). If delete_existing is False any
addition duplicating an existing path element is ignored; if
delete_existing is True (the default) the existing value will be
dropped and the path element will be inserted at the beginning.
To help maintain uniqueness all paths are normalized (using
os.path.normpath and os.path.normcase).

Example:

print('before:', env['ENV']['INCLUDE'])
include_path = '/foo/bar:/foo'
env.PrependENVPath('INCLUDE', include_path)
print('after:', env['ENV']['INCLUDE'])

Yields:

before: /biz:/foo
after: /foo/bar:/foo:/biz

See also env.AppendENVPath.

env.PrependUnique(key=val, [...], [delete_existing=False])
Prepend values to construction variables in the current
construction environment, maintaining uniqueness. Works like
env.Append, except that values are added to the front, rather
than the end, of the construction variable, and values that would
become duplicates are not added. If delete_existing is set to a
true value, then for any duplicate, the existing instance of val
is first removed, then val is inserted, having the effect of
moving it to the front.

Example:

env.PrependUnique(CCFLAGS='-g', FOO=['foo.yyy'])

See also env.Append, env.AppendUnique and env.Prepend.

Progress(callable, [interval]), Progress(string, [interval, file,
overwrite]), Progress(list_of_strings, [interval, file, overwrite])
Allows SCons to show progress made during the build by displaying
a string or calling a function while evaluating Nodes (e.g.
files).

If the first specified argument is a Python callable (a function
or an object that has a __call__ method), the function will be
called once every interval times a Node is evaluated (default 1).
The callable will be passed the evaluated Node as its only
argument. (For future compatibility, it's a good idea to also add
*args and **kwargs as arguments to your function or method
signatures. This will prevent the code from breaking if SCons
ever changes the interface to call the function with additional
arguments in the future.)

An example of a simple custom progress function that prints a
string containing the Node name every 10 Nodes:

def my_progress_function(node, *args, **kwargs):
print('Evaluating node %s!' % node)
Progress(my_progress_function, interval=10)

A more complicated example of a custom progress display object
that prints a string containing a count every 100 evaluated
Nodes. Note the use of \r (a carriage return) at the end so that
the string will overwrite itself on a display:

import sys
class ProgressCounter(object):
count = 0
def __call__(self, node, *args, **kw):
self.count += 100
sys.stderr.write('Evaluated %s nodes\r' % self.count)

Progress(ProgressCounter(), interval=100)

If the first argument to Progress is a string or list of strings,
it is taken as text to be displayed every interval evaluated
Nodes. If the first argument is a list of strings, then each
string in the list will be displayed in rotating fashion every
interval evaluated Nodes.

The default is to print the string on standard output. An
alternate output stream may be specified with the file keyword
argument, which the caller must pass already opened.

The following will print a series of dots on the error output,
one dot for every 100 evaluated Nodes:

import sys
Progress('.', interval=100, file=sys.stderr)

If the string contains the verbatim substring $TARGET;, it will
be replaced with the Node. Note that, for performance reasons,
this is not a regular SCons variable substitution, so you can not
use other variables or use curly braces. The following example
will print the name of every evaluated Node, using a carriage
return) (\r) to cause each line to overwritten by the next line,
and the overwrite keyword argument (default False) to make sure
the previously-printed file name is overwritten with blank
spaces:

import sys
Progress('$TARGET\r', overwrite=True)

A list of strings can be used to implement a "spinner" on the
user's screen as follows, changing every five evaluated Nodes:

Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

Pseudo(target, ...), env.Pseudo(target, ...)
Marks target as a pseudo target, not representing the production
of any physical target file. If any pseudo target does exist,
SCons will abort the build with an error. Multiple targets can be
passed in a single call, and may be strings and/or Nodes. Returns
a list of the affected target nodes.


Pseudo may be useful in conjuction with a builder call (such as
Command) which does not create a physical target, and the
behavior if the target accidentally existed would be incorrect.
This is similar in concept to the GNU make .PHONY target. SCons
also provides a powerful target alias capability (see Alias)
which may provide more flexibility in many situations when
defining target names that are not directly built.

PyPackageDir(modulename), env.PyPackageDir(modulename)
Finds the location of modulename, which can be a string or a
sequence of strings, each representing the name of a Python
module. Construction variables are expanded in modulename.
Returns a Directory Node (see Dir), or a list of Directory Nodes
if modulename is a sequence. None is returned for any module not
found.

When a Tool module which is installed as a Python module is used,
you need to specify a toolpath argument to Tool, Environment or
Clone, as tools outside the standard project locations
(site_scons/site_tools) will not be found otherwise. Using
PyPackageDir allows this path to be discovered at runtime instead
of hardcoding the path.

Example:

env = Environment(
tools=["default", "ExampleTool"],
toolpath=[PyPackageDir("example_tool")]
)

env.Replace(key=val, [...])
Replaces construction variables in the Environment with the
specified keyword arguments.

Example:

env.Replace(CCFLAGS='-g', FOO='foo.xxx')

Repository(directory), env.Repository(directory)
Sets directory as a repository to be searched for files
contributing to the build. Multiple calls to Repository are
allowed, with repositories searched in the given order.
Repositories specified via command-line option have higher
priority.

In scons, a repository is partial or complete copy of the source
tree, from the top-level directory down, containing source files
that can be used to build targets in the current worktree.
Repositories can also contain derived files. An example might be
an official source tree maintained by an integrator. If a
repository contains derived files, they should be the result of
building with SCons, so a signature database (sconsign) is
present in the repository, allowing better decisions on whether
they are up-to-date or not.

Note that if an up-to-date derived file already exists in a
repository, scons will not make a copy in the local directory
tree. If you need a local copy to be made, use the Local method.

Requires(target, prerequisite), env.Requires(target, prerequisite)
Specifies an order-only relationship between target and
prerequisite. The prerequisites will be (re)built, if necessary,
before the target file(s), but the target file(s) do not actually
depend on the prerequisites and will not be rebuilt simply
because the prerequisite file(s) change. target and prerequisite
may each be a string or Node, or a list of strings or Nodes. If
there are multiple target values, the prerequisite(s) are added
to each one. Returns a list of the affected target nodes.

Example:

env.Requires('foo', 'file-that-must-be-built-before-foo')

Return([vars..., stop=True])
Return to the calling SConscript, optionally returning the values
of variables named in vars. Multiple strings containing variable
names may be passed to Return. A string containing white space is
split into individual variable names. Returns the value if one
variable is specified, else returns a tuple of values. Returns an
empty tuple if vars is omitted.

By default Return stops processing the current SConscript and
returns immediately. The optional stop keyword argument may be
set to a false value to continue processing the rest of the
SConscript file after the Return call (this was the default
behavior prior to SCons 0.98.) However, the values returned are
still the values of the variables in the named vars at the point
Return was called.

Examples:

# Returns no values (evaluates False)
Return()

# Returns the value of the 'foo' Python variable.
Return("foo")

# Returns the values of the Python variables 'foo' and 'bar'.
Return("foo", "bar")

# Returns the values of Python variables 'val1' and 'val2'.
Return('val1 val2')

Scanner(function, [name, argument, skeys, path_function, node_class,
node_factory, scan_check, recursive]), env.Scanner(function, [name,
argument, skeys, path_function, node_class, node_factory, scan_check,
recursive])
Creates a Scanner object for the specified function. See manpage
section "Scanner Objects" for a complete explanation of the
arguments and behavior.

SConscript(scriptnames, [exports, variant_dir, duplicate,
must_exist]), env.SConscript(scriptnames, [exports, variant_dir,
duplicate, must_exist]), SConscript(dirs=subdirs, [name=scriptname,
exports, variant_dir, duplicate, must_exist]),
env.SConscript(dirs=subdirs, [name=scriptname, exports, variant_dir,
duplicate, must_exist])
Executes subsidiary SConscript (build configuration) file(s).
There are two ways to call the SConscript function.

The first calling style is to supply one or more SConscript file
names as the first positional argument, which can be a string or
a list of strings. If there is a second positional argument, it
is treated as if the exports keyword argument had been given (see
below). Examples:

SConscript('SConscript') # run SConscript in the current directory
SConscript('src/SConscript') # run SConscript in the src directory
SConscript(['src/SConscript', 'doc/SConscript'])
SConscript(Split('src/SConscript doc/SConscript'))
config = SConscript('MyConfig.py')

The second calling style is to omit the positional argument
naming the script and instead specify directory names using the
dirs keyword argument. The value can be a string or list of
strings. In this case, scons will execute a subsidiary
configuration file named SConscript (by default) in each of the
specified directories. You may specify a name other than
SConscript by supplying an optional name=scriptname keyword
argument. The first three examples below have the same effect as
the first three examples above:

SConscript(dirs='.') # run SConscript in the current directory
SConscript(dirs='src') # run SConscript in the src directory
SConscript(dirs=['src', 'doc'])
SConscript(dirs=['sub1', 'sub2'], name='MySConscript')

The optional exports keyword argument specifies variables to make
available for use by the called SConscripts, which are evaluated
in an isolated context and otherwise do not have access to local
variables from the calling SConscript. The value may be a string
or list of strings representing variable names, or a dictionary
mapping local names to the names they can be imported by. For the
first (scriptnames) calling style, a second positional argument
will also be interpreted as exports; the second (directory)
calling style accepts no positional arguments and must use the
keyword form. These variables are locally exported only to the
called SConscript file(s), and take precedence over any
same-named variables in the global pool managed by the Export
function. The subsidiary SConscript files must use the Import
function to import the variables into their local scope.
Examples:

foo = SConscript('sub/SConscript', exports='env')
SConscript('dir/SConscript', exports=['env', 'variable'])
SConscript(dirs='subdir', exports='env variable')
SConscript(dirs=['one', 'two', 'three'], exports='shared_info')

If the optional variant_dir argument is present, it causes an
effect equivalent to the VariantDir function, but in effect only
within the scope of the SConscript call. The variant_dir argument
is interpreted relative to the directory of the calling
SConscript file. The source directory is the directory in which
the called SConscript file resides and the SConscript file is
evaluated as if it were in the variant_dir directory. Thus:

SConscript('src/SConscript', variant_dir='build')

is equivalent to:

VariantDir('build', 'src')
SConscript('build/SConscript')

If the sources are in the same directory as the SConstruct,

SConscript('SConscript', variant_dir='build')

is equivalent to:

VariantDir('build', '.')
SConscript('build/SConscript')

The optional duplicate argument is interpreted as for VariantDir.
If the variant_dir argument is omitted, the duplicate argument is
ignored. See the description of VariantDir for additional details
and restrictions.


If the optional must_exist is True (the default), an exception is
raised if a requested SConscript file is not found. To allow
missing scripts to be silently ignored (the default behavior
prior to SCons version 3.1), pass must_exist=False in the
SConscript call.


Changed in 4.6.0: must_exist now defaults to True.

Here are some composite examples:

# collect the configuration information and use it to build src and doc
shared_info = SConscript('MyConfig.py')
SConscript('src/SConscript', exports='shared_info')
SConscript('doc/SConscript', exports='shared_info')

# build debugging and production versions. SConscript
# can use Dir('.').path to determine variant.
SConscript('SConscript', variant_dir='debug', duplicate=0)
SConscript('SConscript', variant_dir='prod', duplicate=0)

# build debugging and production versions. SConscript
# is passed flags to use.
opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' }
SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts)
opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' }
SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)

# build common documentation and compile for different architectures
SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0)
SConscript('src/SConscript', variant_dir='build/x86', duplicate=0)
SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)


SConscript returns the values of any variables named by the
executed SConscript file(s) in arguments to the Return function.
If a single SConscript call causes multiple scripts to be
executed, the return value is a tuple containing the returns of
each of the scripts. If an executed script does not explicitly
call Return, it returns None.

SConscriptChdir(value)
By default, scons changes its working directory to the directory
in which each subsidiary SConscript file lives while reading and
processing that script. This behavior may be disabled by
specifying an argument which evaluates false, in which case scons
will stay in the top-level directory while reading all SConscript
files. (This may be necessary when building from repositories,
when all the directories in which SConscript files may be found
don't necessarily exist locally.) You may enable and disable this
ability by calling SConscriptChdir multiple times.

Example:

SConscriptChdir(False)
SConscript('foo/SConscript') # will not chdir to foo
SConscriptChdir(True)
SConscript('bar/SConscript') # will chdir to bar

SConsignFile([name, dbm_module]), env.SConsignFile([name,
dbm_module])
Specify where to store the SCons file signature database, and
which database format to use. This may be useful to specify
alternate database files and/or file locations for different
types of builds.

The optional name argument is the base name of the database
file(s). If not an absolute path name, these are placed relative
to the directory containing the top-level SConstruct file. The
default is .sconsign. The actual database file(s) stored on disk
may have an appropriate suffix appended by the chosen dbm_module

The optional dbm_module argument specifies which Python database
module to use for reading/writing the file. The module must be
imported first; then the imported module name is passed as the
argument. The default is a custom SCons.dblite module that uses
pickled Python data structures, which works on all Python
versions. See documentation of the Python dbm module for other
available types.

If called with no arguments, the database will default to
.sconsign.dblite in the top directory of the project, which is
also the default if if SConsignFile is not called.

The setting is global, so the only difference between the global
function and the environment method form is variable expansion on
name. There should only be one active call to this
function/method in a given build setup.

If name is set to None, scons will store file signatures in a
separate .sconsign file in each directory, not in a single
combined database file. This is a backwards-compatibility measure
to support what was the default behavior prior to SCons 0.97
(i.e. before 2008). Use of this mode is discouraged and may be
deprecated in a future SCons release.

Examples:

# Explicitly stores signatures in ".sconsign.dblite"
# in the top-level SConstruct directory (the default behavior).
SConsignFile()

# Stores signatures in the file "etc/scons-signatures"
# relative to the top-level SConstruct directory.
# SCons will add a database suffix to this name.
SConsignFile("etc/scons-signatures")

# Stores signatures in the specified absolute file name.
# SCons will add a database suffix to this name.
SConsignFile("/home/me/SCons/signatures")

# Stores signatures in a separate .sconsign file
# in each directory.
SConsignFile(None)

# Stores signatures in a GNU dbm format .sconsign file
import dbm.gnu
SConsignFile(dbm_module=dbm.gnu)

env.SetDefault(key=val, [...])
Sets construction variables to default values specified with the
keyword arguments if (and only if) the variables are not already
set. The following statements are equivalent:

env.SetDefault(FOO='foo')
if 'FOO' not in env:
env['FOO'] = 'foo'

SetOption(name, value), env.SetOption(name, value)
Sets scons option variable name to value. These options are all
also settable via command-line options but the variable name may
differ from the command-line option name - see the table for
correspondences. A value set via command-line option will take
precedence over one set with SetOption, which allows setting a
project default in the scripts and temporarily overriding it via
command line. SetOption calls can also be placed in the
site_init.py file.

See the documentation in the manpage for the corresponding
command line option for information about each specific option.
The value parameter is mandatory, for option values which are
boolean in nature (that is, the command line option does not take
an argument) use a value which evaluates to true (e.g. True, 1)
or false (e.g. False, 0).

Options which affect the reading and processing of SConscript
files are not settable using SetOption since those files must be
read in order to find the SetOption call in the first place.

For project-specific options (sometimes called local options)
added via an AddOption call, SetOption is available only after
the AddOption call has completed successfully, and only if that
call included the settable=True argument.

The settable variables with their associated command-line options
are:

+------------------------+---------------------------+-----------------+
|Settable name | Command-line options | Notes |
+------------------------+---------------------------+-----------------+
|clean | -c, --clean, | |
| | --remove | |
+------------------------+---------------------------+-----------------+
|diskcheck | --diskcheck | |
+------------------------+---------------------------+-----------------+
|duplicate | --duplicate | |
+------------------------+---------------------------+-----------------+
|experimental | --experimental | since 4.2 |
+------------------------+---------------------------+-----------------+
|hash_chunksize | --hash-chunksize | Actually sets |
| | | md5_chunksize. |
| | | since 4.2 |
+------------------------+---------------------------+-----------------+
|hash_format | --hash-format | since 4.2 |
+------------------------+---------------------------+-----------------+
|help | -h, --help | |
+------------------------+---------------------------+-----------------+
|implicit_cache | --implicit-cache | |
+------------------------+---------------------------+-----------------+
|implicit_deps_changed | --implicit-deps-changed | Also sets |
| | | implicit_cache. |
| | | (settable since |
| | | 4.2) |
+------------------------+---------------------------+-----------------+
|implicit_deps_unchanged | --implicit-deps-unchanged | Also sets |
| | | implicit_cache. |
| | | (settable since |
| | | 4.2) |
+------------------------+---------------------------+-----------------+
|max_drift | --max-drift | |
+------------------------+---------------------------+-----------------+
|md5_chunksize | --md5-chunksize | |
+------------------------+---------------------------+-----------------+
|no_exec | -n, --no-exec, | |
| | --just-print, | |
| | --dry-run, --recon | |
+------------------------+---------------------------+-----------------+
|no_progress | -Q | See [7] |
+------------------------+---------------------------+-----------------+
|num_jobs | -j, --jobs | |
+------------------------+---------------------------+-----------------+
|random | --random | |
+------------------------+---------------------------+-----------------+
|silent | -s, --silent, | |
| | --quiet | |
+------------------------+---------------------------+-----------------+
|stack_size | --stack-size | |
+------------------------+---------------------------+-----------------+
|warn | --warn | |
+------------------------+---------------------------+-----------------+
|---- [a] If no_progress is set via SetOption in an SConscript file |
|(but not if set in a site_init.py file) there will still be an |
|initial status message about reading SConscript files since SCons has |
|to start reading them before it can see the SetOption. |
+----------------------------------------------------------------------+
Example:

SetOption('max_drift', 0)

SideEffect(side_effect, target), env.SideEffect(side_effect, target)
Declares side_effect as a side effect of building target. Both
side_effect and target can be a list, a file name, or a node. A
side effect is a target file that is created or updated as a side
effect of building other targets. For example, a Windows PDB file
is created as a side effect of building the .obj files for a
static library, and various log files are created updated as side
effects of various TeX commands. If a target is a side effect of
multiple build commands, scons will ensure that only one set of
commands is executed at a time. Consequently, you only need to
use this method for side-effect targets that are built as a
result of multiple build commands.

Because multiple build commands may update the same side effect
file, by default the side_effect target is not automatically
removed when the target is removed by the -c option. (Note,
however, that the side_effect might be removed as part of
cleaning the directory in which it lives.) If you want to make
sure the side_effect is cleaned whenever a specific target is
cleaned, you must specify this explicitly with the Clean or
env.Clean function.

This function returns the list of side effect Node objects that
were successfully added. If the list of side effects contained
any side effects that had already been added, they are not added
and included in the returned list.

Split(arg), env.Split(arg)
If arg is a string, splits on whitespace and returns a list of
strings without whitespace. This mode is the most common case,
and can be used to split a list of filenames (for example) rather
than having to type them as a list of individually quoted words.
If arg is a list or tuple returns the list or tuple unchanged. If
arg is any other type of object, returns a list containing just
the object. These non-string cases do not actually do any
spliting, but allow an argument variable to be passed to Split
without having to first check its type.

Example:

files = Split("f1.c f2.c f3.c")
files = env.Split("f4.c f5.c f6.c")
files = Split("""
f7.c
f8.c
f9.c
""")

env.subst(input, [raw, target, source, conv])
Performs construction variable interpolation (substitution) on
input, which can be a string or a sequence. Substitutable
elements take the form ${expression}, although if there is no
ambiguity in recognizing the element, the braces can be omitted.
A literal $ can be entered by using $$.

By default, leading or trailing white space will be removed from
the result, and all sequences of white space will be compressed
to a single space character. Additionally, any $( and $)
character sequences will be stripped from the returned string,
The optional raw argument may be set to 1 if you want to preserve
white space and $(-$) sequences. The raw argument may be set to 2
if you want to additionally discard all characters between any $(
and $) pairs (as is done for signature calculation).

If input is a sequence (list or tuple), the individual elements
of the sequence will be expanded, and the results will be
returned as a list.

The optional target and source keyword arguments must be set to
lists of target and source nodes, respectively, if you want the
$TARGET, $TARGETS, $SOURCE and $SOURCES to be available for
expansion. This is usually necessary if you are calling env.subst
from within a Python function used as an SCons action.

Returned string values or sequence elements are converted to
their string representation by default. The optional conv
argument may specify a conversion function that will be used in
place of the default. For example, if you want Python objects
(including SCons Nodes) to be returned as Python objects, you can
use a Python lambda expression to pass in an unnamed function
that simply returns its unconverted argument.

Example:

print(env.subst("The C compiler is: $CC"))

def compile(target, source, env):
sourceDir = env.subst(
"${SOURCE.srcdir}",
target=target,
source=source
)

source_nodes = env.subst('$EXPAND_TO_NODELIST', conv=lambda x: x)

Tag(node, tags)
Annotates file or directory Nodes with information about how the
Package Builder should package those files or directories. All
Node-level tags are optional.

Examples:

# makes sure the built library will be installed with 644 file access mode
Tag(Library('lib.c'), UNIX_ATTR="0o644")

# marks file2.txt to be a documentation file
Tag('file2.txt', DOC)

Tool(name, [toolpath, key=value, ...]), env.Tool(name, [toolpath,
key=value, ...])
Locates the tool specification module name and returns a callable
tool object for that tool. When the environment method (env.Tool)
form is used, the tool object is automatically called before the
method returns to update env, and name is appended to the $TOOLS
construction variable in that environment. When the global
function Tool form is used, the tool object is constructed but
not called, as it lacks the context of an environment to update,
and the returned object needs to be used to arrange for the call.

The tool module is searched for in the tool search paths (see the
Tools section in the manual page for details) and in any paths
specified by the optional toolpath parameter, which must be a
list of strings. If toolpath is omitted, the toolpath supplied
when the environment was created, if any, is used.

Any remaining keyword arguments are saved in the tool object, and
will be passed to the tool module's generate function when the
tool object is actually called. The generate function can update
the construction environment with construction variables and
arrange any other initialization needed to use the mechanisms
that tool describes, and can use these extra arguments to help
guide its actions.


Changed in version 4.2: env.Tool now returns the tool object,
previously it did not return (i.e. returned None).

Examples:

env.Tool('gcc')
env.Tool('opengl', toolpath=['build/tools'])

The returned tool object can be passed to an Environment or Clone
call as part of the tools keyword argument, in which case the
tool is applied to the environment being constructed, or it can
be called directly, in which case a construction environment to
update must be passed as the argument. Either approach will also
update the $TOOLS construction variable.

Examples:

env = Environment(tools=[Tool('msvc')])

env = Environment()
msvctool = Tool('msvc')
msvctool(env) # adds 'msvc' to the TOOLS variable
gltool = Tool('opengl', toolpath = ['tools'])
gltool(env) # adds 'opengl' to the TOOLS variable

ValidateOptions([throw_exception=False])
Check that all the options specified on the command line are
either SCons built-in options or defined via calls to AddOption.
SCons will eventually fail on unknown options anyway, but calling
this function allows the build to "fail fast" before executing
expensive logic later in the build.

This function should only be called after the last AddOption call
in your SConscript logic. Be aware that some tools call
AddOption, if you are getting error messages for arguments that
they add, you will need to ensure that those tools are loaded
before calling ValidateOptions.

If there are any unknown command line options, ValidateOptions
prints an error message and exits with an error exit status. If
the optional throw_exception argument is True (default is False),
a SConsBadOptionError is raised, giving an opportunity for the
SConscript logic to catch that exception and handle invalid
options appropriately. Note that this exception name needs to be
imported (see the example below).

A common build problem is typos (or thinkos) - a user enters an
option that is just a little off the expected value, or perhaps a
different word with a similar meaning. It may be useful to abort
the build before going too far down the wrong path. For example:

$ scons --compilers=mingw # the correct flag is --compiler


Here SCons could go off and run a bunch of configure steps with
the default value of --compiler, since the incorrect command line
did not actually supply a value to it, costing developer time to
track down why the configure logic made the "wrong" choices. This
example shows catching this:

from SCons.Script.SConsOptions import SConsBadOptionError

AddOption(
'--compiler',
dest='compiler',
action='store',
default='gcc',
type='string',
)

# ... other SConscript logic ...

try:
ValidateOptions(throw_exception=True)
except SConsBadOptionError as e:
print(f"ValidateOptions detects a fail: ", e.opt_str)
Exit(3)


New in version 4.5.0

Value(value, [built_value], [name]), env.Value(value, [built_value],
[name])
Returns a Node object representing the specified Python value.
Value Nodes can be used as dependencies of targets. If the string
representation of the Value Node changes between SCons runs, it
is considered out-of-date and any targets depending on it will be
rebuilt. Since Value Nodes have no filesystem representation,
timestamps are not used; the timestamp deciders perform the same
content-based up to date check.

The optional built_value argument can be specified when the Value
Node is created to indicate the Node should already be considered
"built."

The optional name parameter can be provided as an alternative
name for the resulting Value node; this is advised if the value
parameter cannot be converted to a string.

Value Nodes have a write method that can be used to "build" a
Value Node by setting a new value. The corresponding read method
returns the built value of the Node.


Changed in version 4.0: the name parameter was added.

Examples:

env = Environment()

def create(target, source, env):
"""Action function to create a file from a Value.

Writes 'prefix=$SOURCE' into the file name given as $TARGET.
"""
with open(str(target[0]), 'wb') as f:
f.write(b'prefix=' + source[0].get_contents() + b'\n')

# Fetch the prefix= argument, if any, from the command line.
# Use /usr/local as the default.
prefix = ARGUMENTS.get('prefix', '/usr/local')

# Attach builder named Config to the construction environment
# using the 'create' action function above.
env['BUILDERS']['Config'] = Builder(action=create)
env.Config(target='package-config', source=Value(prefix))

def build_value(target, source, env):
"""Action function to "build" a Value.

Writes contents of $SOURCE into $TARGET, thus updating if it existed.
"""
target[0].write(source[0].get_contents())

output = env.Value('before')
input = env.Value('after')

# Attach a builder named UpdateValue to the construction environment
# using the 'build_value' action function above.
env['BUILDERS']['UpdateValue'] = Builder(action=build_value)
env.UpdateValue(target=Value(output), source=Value(input))

VariantDir(variant_dir, src_dir, [duplicate]),
env.VariantDir(variant_dir, src_dir, [duplicate])
Sets up a mapping to define a variant build directory in
variant_dir. src_dir must not be underneath variant_dir. A
VariantDir mapping is global, even if called using the
env.VariantDir form. VariantDir can be called multiple times
with the same src_dir to set up multiple variant builds with
different options.

Note if variant_dir is not under the project top directory,
target selection rules will not pick targets in the variant
directory unless they are explicitly specified.

When files in variant_dir are referenced, SCons backfills as
needed with files from src_dir to create a complete build
directory. By default, SCons physically duplicates the source
files, SConscript files, and directory structure as needed into
the variant directory. Thus, a build performed in the variant
directory is guaranteed to be identical to a build performed in
the source directory even if intermediate source files are
generated during the build, or if preprocessors or other scanners
search for included files using paths relative to the source
file, or if individual compilers or other invoked tools are
hard-coded to put derived files in the same directory as source
files. Only the files SCons calculates are needed for the build
are duplicated into variant_dir. If possible on the platform, the
duplication is performed by linking rather than copying. This
behavior is affected by the --duplicate command-line option.

Duplicating the source files may be disabled by setting the
duplicate argument to False. This will cause SCons to invoke
Builders using the path names of source files in src_dir and the
path names of derived files within variant_dir. This is more
efficient than duplicating, and is safe for most builds; revert
to duplicate=True if it causes problems.


VariantDir works most naturally when used with a subsidiary
SConscript file. The subsidiary SConscript file must be called as
if it were in variant_dir, regardless of the value of duplicate.
When calling an SConscript file, you can use the exports keyword
argument to pass parameters (individually or as an appropriately
set up environment) so the SConscript can pick up the right
settings for that variant build. The SConscript must Import these
to use them. Example:

env1 = Environment(...settings for variant1...)
env2 = Environment(...settings for variant2...)

# run src/SConscript in two variant directories
VariantDir('build/variant1', 'src')
SConscript('build/variant1/SConscript', exports={"env": env1})
VariantDir('build/variant2', 'src')
SConscript('build/variant2/SConscript', exports={"env": env2})

See also the SConscript function for another way to specify a
variant directory in conjunction with calling a subsidiary
SConscript file.

More examples:

# use names in the build directory, not the source directory
VariantDir('build', 'src', duplicate=0)
Program('build/prog', 'build/source.c')

# this builds both the source and docs in a separate subtree
VariantDir('build', '.', duplicate=0)
SConscript(dirs=['build/src','build/doc'])

# same as previous example, but only uses SConscript
SConscript(dirs='src', variant_dir='build/src', duplicate=0)
SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)

WhereIs(program, [path, pathext, reject]), env.WhereIs(program,
[path, pathext, reject])
Searches for the specified executable program, returning the full
path to the program or None.

When called as a construction environment method, searches the
paths in the path keyword argument, or if None (the default) the
paths listed in the construction environment
(env['ENV']['PATH']). The external environment's path list
(os.environ['PATH']) is used as a fallback if the key
env['ENV']['PATH'] does not exist.

On Windows systems, searches for executable programs with any of
the file extensions listed in the pathext keyword argument, or if
None (the default) the pathname extensions listed in the
construction environment (env['ENV']['PATHEXT']). The external
environment's pathname extensions list (os.environ['PATHEXT']) is
used as a fallback if the key env['ENV']['PATHEXT'] does not
exist.

When called as a global function, uses the external environment's
path os.environ['PATH'] and path extensions
os.environ['PATHEXT'], respectively, if path and pathext are
None.

Will not select any path name or names in the optional reject
list.

SConscript Variables

In addition to the global functions and methods, scons supports a
number of variables that can be used for run-time queries in
SConscript files to affect how you want the build to be performed.

ARGLIST
A list of the variable=value build variable arguments specified
on the command line. Each element in the list is a tuple
consisting of the variable and its value. The separate variable
and value elements of the tuple can be accessed by subscripting
for elements [0] and [1] of the tuple, or, more readably, by
using tuple unpacking. Examples:

print("first variable, value =", ARGLIST[0][0], ARGLIST[0][1])
print("second variable, value =", ARGLIST[1][0], ARGLIST[1][1])
var, value = ARGLIST[2]
print("third variable, value =", var, value)
for var, value in ARGLIST:
# process variable and value

The values obtained from ARGLIST (or from ARGUMENTS) are always
strings since they originate from outside the SCons process. As
"untrusted data", they should be validated before usage, and may
need conversion to an appropriate type.

ARGUMENTS
A dictionary of all the variable=value build variable arguments
specified on the command line. The dictionary is in command-line
order, so if a given variable has more than one value assigned to
it on the command line, the last (right-most) value is the one
saved in the ARGUMENTS dictionary.

Example:

if ARGUMENTS.get("debug", ""):
env = Environment(CCFLAGS="-g")
else:
env = Environment()

See also ARGLIST.

BUILD_TARGETS
A list of the targets which scons has been asked to build. The
contents will be either those targets listed on the command line,
or, if none, those targets set via calls to the Default function.
It does not contain any dependent targets that scons selects for
building as a result of making the sure the specified targets are
up to date, if those targets did not appear on the command line.
The list is empty if neither command line targets nor Default
calls are present.

The elements of this list may be strings or nodes, so you should
run the list through the Python str function to make sure any
Node path names are converted to strings.

Because this list may be taken from the list of targets specified
using the Default function, the contents of the list may change
on each successive call to Default. See DEFAULT_TARGETS for
additional information.

Example:

if 'foo' in BUILD_TARGETS:
print("Don't forget to test the `foo' program!")
if 'special/program' in BUILD_TARGETS:
SConscript('special')

COMMAND_LINE_TARGETS
A list of the targets explicitly specified on the command line.
If there are command line targets, this list has the same
contents as BUILD_TARGETS. If there are no targets specified on
the command line, this list is empty. The elements of this list
are strings. This can be used, for example, to take specific
actions only when a certain target(s) are explicitly requested
for building.

Example:

if 'foo' in COMMAND_LINE_TARGETS:
print("Don't forget to test the `foo' program!")
if 'special/program' in COMMAND_LINE_TARGETS:
SConscript('special')

DEFAULT_TARGETS
A list of the target nodes that have been specified using the
Default function. If there are no command line targets, this list
will have the same contents as BUILD_TARGETS. Since the elements
of the list are nodes, you need to call the Python str function
on them to get the path name for each Node.

Example:

print(str(DEFAULT_TARGETS[0]))
if 'foo' in [str(t) for t in DEFAULT_TARGETS]:
print("Don't forget to test the `foo' program!")

The contents of the DEFAULT_TARGETS list changes on each
successive call to the Default function:

print([str(t) for t in DEFAULT_TARGETS]) # originally []
Default('foo')
print([str(t) for t in DEFAULT_TARGETS]) # now a node ['foo']
Default('bar')
print([str(t) for t in DEFAULT_TARGETS]) # now a node ['foo', 'bar']
Default(None)
print([str(t) for t in DEFAULT_TARGETS]) # back to []

Consequently, be sure to use DEFAULT_TARGETS only after you've
made all of your Default() calls, or else simply be careful of
the order of these statements in your SConscript files so that
you don't look for a specific default target before it's actually
been added to the list.

These variables may be accessed from custom Python modules that you
import into an SConscript file by adding the following to the Python
module:

from SCons.Script import *

Construction Variables

Construction Variables are key-value pairs used to store information
in a construction environment that is needed needed for builds using
that environment. Construction variable naming must follow the same
rules as Python identifier naming: the initial character must be an
underscore or letter, followed by any number of underscores, letters,
or digits. The convention is to use uppercase for all letters for
easier visual identification.

Construction variables are used to hold many different types of
information. For example, the $CPPDEFINES variable is how to tell a
C/C++ compiler about preprocessor macros you need for your build. The
tool discovery that SCons performs will cause the $CXX variable to
hold the name of the C++ compiler, if one was detected on the system,
but you can give it a different value to force a compiler command of
a different name to be used. Some variables contain lists of filename
suffixes that are recognized by a particular compiler chain.
$BUILDERS contains a mapping of configured Builder names (e.g.
Textfile) to the actual Builder instance to call when that Builder is
used. Construction variables may include references to other
construction variables: the same tool which set up the C/C++ compiler
will also set up an "action string", describing how to invoke that
compiler, in $CXXCOM, which contains other construction variables
using $VARIABLE syntax. These references will be expanded and
replaced on use (see Variable Substitution).

Construction variables are referenced as if they were keys and values
in a Python dictionary:

env["CC"] = "cc"
flags = env.get("CPPDEFINES", [])

Construction variables can also be retrieved and set by using the
Dictionary method of the construction environment to create an actual
dictionary:

cvars = env.Dictionary()
cvars["CC"] = "cc"

in the previous example, since cvars is an external copy, the value
of $CC in the construction environment itself is not changed by the
assignment.

Construction variables can set by passing them as keyword arguments
when creating a new construction environment:

env = Environment(CC="cc")

or when copying a construction environment using the Clone method:

env2 = env.Clone(CC="cl.exe")

Construction variables can also be supplied as keyword arguments to a
builder, in which case those settings affect only the work done by
that builder call, and not the construction environment as a whole.
This concept is called an override:

env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

Many useful construction variables are automatically defined by
SCons, tuned to the specific platform in use, and you can modify
these or define any additional construction variables for use in your
own Builders, Scanners and other tools. Take care not to overwrite
ones which SCons is using. The following is a list of predefined
construction variables. Pay attention to whether the values are ones
you may be expected to set vs. ones that are set to expected values
by internal tools and other initializations and probably should not
be modified.

Note the actual list available at execution time will never include
all of these, as the ones detected as not being applicable (wrong
platform, necessary external command or files not installed, etc.)
will not be set up. Correct build setups should be resilient to the
possible absence of certain construction variables before using them,
for example by using a Python dictionary get method to retrieve the
value and taking alternative action if the return indicates the
variable is unset. The env.Dump method can be called to examine the
construction variables set in a particular environment.

__LDMODULEVERSIONFLAGS
This construction variable automatically introduces
$_LDMODULEVERSIONFLAGS if $LDMODULEVERSION is set. Otherwise, it
evaluates to an empty string.

__SHLIBVERSIONFLAGS
This construction variable automatically introduces
$_SHLIBVERSIONFLAGS if $SHLIBVERSION is set. Otherwise, it
evaluates to an empty string.

APPLELINK_COMPATIBILITY_VERSION
On Mac OS X this is used to set the linker flag:
-compatibility_version

The value is specified as X[.Y[.Z]] where X is between 1 and
65535, Y can be omitted or between 1 and 255, Z can be omitted or
between 1 and 255. This value will be derived from $SHLIBVERSION
if not specified. The lowest digit will be dropped and replaced
by a 0.

If the $APPLELINK_NO_COMPATIBILITY_VERSION is set then no
-compatibility_version will be output.

See MacOS's ld manpage for more details

_APPLELINK_COMPATIBILITY_VERSION
A macro (by default a generator function) used to create the
linker flags to specify apple's linker's -compatibility_version
flag. The default generator uses $APPLELINK_COMPATIBILITY_VERSION
and $APPLELINK_NO_COMPATIBILITY_VERSION and $SHLIBVERSION to
determine the correct flag.

APPLELINK_CURRENT_VERSION
On Mac OS X this is used to set the linker flag: -current_version

The value is specified as X[.Y[.Z]] where X is between 1 and
65535, Y can be omitted or between 1 and 255, Z can be omitted or
between 1 and 255. This value will be set to $SHLIBVERSION if not
specified.

If the $APPLELINK_NO_CURRENT_VERSION is set then no
-current_version will be output.

See MacOS's ld manpage for more details

_APPLELINK_CURRENT_VERSION
A macro (by default a generator function) used to create the
linker flags to specify apple's linker's -current_version flag.
The default generator uses $APPLELINK_CURRENT_VERSION and
$APPLELINK_NO_CURRENT_VERSION and $SHLIBVERSION to determine the
correct flag.

APPLELINK_NO_COMPATIBILITY_VERSION
Set this to any True (1|True|non-empty string) value to disable
adding -compatibility_version flag when generating versioned
shared libraries.

This overrides $APPLELINK_COMPATIBILITY_VERSION.

APPLELINK_NO_CURRENT_VERSION
Set this to any True (1|True|non-empty string) value to disable
adding -current_version flag when generating versioned shared
libraries.

This overrides $APPLELINK_CURRENT_VERSION.

AR
The static library archiver.

ARCHITECTURE
Specifies the system architecture for which the package is being
built. The default is the system architecture of the machine on
which SCons is running. This is used to fill in the Architecture:
field in an Ipkg control file, and the BuildArch: field in the
RPM .spec file, as well as forming part of the name of a
generated RPM package file.

See the Package builder.

ARCOM
The command line used to generate a static library from object
files.

ARCOMSTR
The string displayed when a static library is generated from
object files. If this is not set, then $ARCOM (the command line)
is displayed.

env = Environment(ARCOMSTR = "Archiving $TARGET")

ARFLAGS
General options passed to the static library archiver.

AS
The assembler.

ASCOM
The command line used to generate an object file from an
assembly-language source file.

ASCOMSTR
The string displayed when an object file is generated from an
assembly-language source file. If this is not set, then $ASCOM
(the command line) is displayed.

env = Environment(ASCOMSTR = "Assembling $TARGET")

ASFLAGS
General options passed to the assembler.

ASPPCOM
The command line used to assemble an assembly-language source
file into an object file after first running the file through the
C preprocessor. Any options specified in the $ASFLAGS and
$CPPFLAGS construction variables are included on this command
line.

ASPPCOMSTR
The string displayed when an object file is generated from an
assembly-language source file after first running the file
through the C preprocessor. If this is not set, then $ASPPCOM
(the command line) is displayed.

env = Environment(ASPPCOMSTR = "Assembling $TARGET")

ASPPFLAGS
General options when an assembling an assembly-language source
file into an object file after first running the file through the
C preprocessor. The default is to use the value of $ASFLAGS.

BIBTEX
The bibliography generator for the TeX formatter and typesetter
and the LaTeX structured formatter and typesetter.

BIBTEXCOM
The command line used to call the bibliography generator for the
TeX formatter and typesetter and the LaTeX structured formatter
and typesetter.

BIBTEXCOMSTR
The string displayed when generating a bibliography for TeX or
LaTeX. If this is not set, then $BIBTEXCOM (the command line) is
displayed.

env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

BIBTEXFLAGS
General options passed to the bibliography generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

BUILDERS
A dictionary mapping the names of the builders available through
the construction environment to underlying Builder objects.
Custom builders need to be added to this to make them available.

A platform-dependent default list of builders such as Program,
Library etc. is used to populate this construction variable when
the construction environment is initialized via the
presence/absence of the tools those builders depend on.
$BUILDERS can be examined to learn which builders will actually
be available at run-time.

Note that if you initialize this construction variable through
assignment when the construction environment is created, that
value for $BUILDERS will override any defaults:

bld = Builder(action='foobuild < $SOURCE > $TARGET')
env = Environment(BUILDERS={'NewBuilder': bld})

To instead use a new Builder object in addition to the default
Builders, add your new Builder object like this:

env = Environment()
env.Append(BUILDERS={'NewBuilder': bld})

or this:

env = Environment()
env['BUILDERS']['NewBuilder'] = bld

CACHEDIR_CLASS
The class type that SCons should use when instantiating a new
CacheDir in this construction environment. Must be a subclass of
the SCons.CacheDir.CacheDir class.

CC
The C compiler.

CCCOM
The command line used to compile a C source file to a (static)
object file. Any options specified in the $CFLAGS, $CCFLAGS and
$CPPFLAGS construction variables are included on this command
line. See also $SHCCCOM for compiling to shared objects.

CCCOMSTR
If set, the string displayed when a C source file is compiled to
a (static) object file. If not set, then $CCCOM (the command
line) is displayed. See also $SHCCCOMSTR for compiling to shared
objects.

env = Environment(CCCOMSTR = "Compiling static object $TARGET")

CCDEPFLAGS
Options to pass to C or C++ compiler to generate list of
dependency files.

This is set only by compilers which support this functionality.
(gcc, clang, and msvc currently)

CCFLAGS
General options that are passed to the C and C++ compilers. See
also $SHCCFLAGS for compiling to shared objects.

CCPCHFLAGS
Options added to the compiler command line to support building
with precompiled headers. The default value expands expands to
the appropriate Microsoft Visual C++ command-line options when
the $PCH construction variable is set.

CCPDBFLAGS
Options added to the compiler command line to support storing
debugging information in a Microsoft Visual C++ PDB file. The
default value expands expands to appropriate Microsoft Visual C++
command-line options when the $PDB construction variable is set.

The Microsoft Visual C++ compiler option that SCons uses by
default to generate PDB information is /Z7. This works correctly
with parallel (-j) builds because it embeds the debug information
in the intermediate object files, as opposed to sharing a single
PDB file between multiple object files. This is also the only way
to get debug information embedded into a static library. Using
the /Zi instead may yield improved link-time performance,
although parallel builds will no longer work.

You can generate PDB files with the /Zi switch by overriding the
default $CCPDBFLAGS variable as follows:

env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']

An alternative would be to use the /Zi to put the debugging
information in a separate .pdb file for each object file by
overriding the $CCPDBFLAGS variable as follows:

env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

CCVERSION
The version number of the C compiler. This may or may not be set,
depending on the specific C compiler being used.

CFILESUFFIX
The suffix for C source files. This is used by the internal CFile
builder when generating C files from Lex (.l) or YACC (.y) input
files. The default suffix, of course, is .c (lower case). On
case-insensitive systems (like Windows), SCons also treats .C
(upper case) files as C files.

CFLAGS
General options that are passed to the C compiler (C only; not
C++). See also $SHCFLAGS for compiling to shared objects.

CHANGE_SPECFILE
A hook for modifying the file that controls the packaging build
(the .spec for RPM, the control for Ipkg, the .wxs for MSI). If
set, the function will be called after the SCons template for the
file has been written.

See the Package builder.

CHANGED_SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

CHANGED_TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

CHANGELOG
The name of a file containing the change log text to be included
in the package. This is included as the %changelog section of the
RPM .spec file.

See the Package builder.

COMPILATIONDB_COMSTR
The string displayed when the CompilationDatabase builder's
action is run.

COMPILATIONDB_PATH_FILTER
A string which instructs CompilationDatabase to only include
entries where the output member matches the pattern in the filter
string using fnmatch, which uses glob style wildcards.

The default value is an empty string '', which disables
filtering.

COMPILATIONDB_USE_ABSPATH
A boolean flag to instruct CompilationDatabase whether to write
the file and output members in the compilation database using
absolute or relative paths.

The default value is False (use relative paths)

_concat
A function used to produce variables like $_CPPINCFLAGS. It takes
four mandatory arguments, and up to 4 additional optional
arguments: 1) a prefix to concatenate onto each element, 2) a
list of elements, 3) a suffix to concatenate onto each element,
4) an environment for variable interpolation, 5) an optional
function that will be called to transform the list before
concatenation, 6) an optionally specified target (Can use
TARGET), 7) an optionally specified source (Can use SOURCE), 8)
optional affect_signature flag which will wrap non-empty returned
value with $( and $) to indicate the contents should not affect
the signature of the generated command line.

env['_CPPINCFLAGS'] = '${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE, affect_signature=False)}'


CONFIGUREDIR
The name of the directory in which Configure context test files
are written. The default is .sconf_temp in the top-level
directory containing the SConstruct file.

If variant directories are in use, and the configure check
results should not be shared between variants, you can set
$CONFIGUREDIR and $CONFIGURELOG so they are unique per variant
directory.

CONFIGURELOG
The name of the Configure context log file. The default is
config.log in the top-level directory containing the SConstruct
file.

If variant directories are in use, and the configure check
results should not be shared between variants, you can set
$CONFIGUREDIR and $CONFIGURELOG so they are unique per variant
directory.

_CPPDEFFLAGS
An automatically-generated construction variable containing the C
preprocessor command-line options to define values. The value of
$_CPPDEFFLAGS is created by respectively prepending and appending
$CPPDEFPREFIX and $CPPDEFSUFFIX to each definition in
$CPPDEFINES.

CPPDEFINES
A platform independent specification of C preprocessor macro
definitions. The definitions are added to command lines through
the automatically-generated $_CPPDEFFLAGS construction variable,
which is constructed according to the contents of $CPPDEFINES:

+o If $CPPDEFINES is a string, the values of the $CPPDEFPREFIX
and $CPPDEFSUFFIX construction variables are respectively
prepended and appended to each definition in $CPPDEFINES,
split on whitespace.

# Adds -Dxyz to POSIX compiler command lines,
# and /Dxyz to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES='xyz')

+o If $CPPDEFINES is a list, the values of the $CPPDEFPREFIX and
$CPPDEFSUFFIX construction variables are respectively
prepended and appended to each element in the list. If any
element is a tuple (or list) then the first item of the tuple
is the macro name and the second is the macro definition. If
the definition is not omitted or None, the name and
definition are combined into a single name=definition item
before the prepending/appending.

# Adds -DB=2 -DA to POSIX compiler command lines,
# and /DB=2 /DA to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES=[('B', 2), 'A'])

+o If $CPPDEFINES is a dictionary, the values of the
$CPPDEFPREFIX and $CPPDEFSUFFIX construction variables are
respectively prepended and appended to each key from the
dictionary. If the value for a key is not None, then the key
(macro name) and the value (macros definition) are combined
into a single name=definition item before the
prepending/appending.

# Adds -DA -DB=2 to POSIX compiler command lines,
# or /DA /DB=2 to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES={'B':2, 'A':None})

Depending on how contents are added to $CPPDEFINES, it may be
transformed into a compound type, for example a list containing
strings, tuples and/or dictionaries. SCons can correctly expand
such a compound type.

Note that SCons may call the compiler via a shell. If a macro
definition contains characters such as spaces that have meaning
to the shell, or is intended to be a string value, you may need
to use the shell's quoting syntax to avoid interpretation by the
shell before the preprocessor sees it. Function-like macros are
not supported via this mechanism (and some compilers do not even
implement that functionality via the command lines). When
quoting, note that one set of quote characters are used to define
a Python string, then quotes embedded inside that would be
consumed by the shell unless escaped. These examples may help
illustrate:

env = Environment(CPPDEFINES=['USE_ALT_HEADER=\\"foo_alt.h\\"'])
env = Environment(CPPDEFINES=[('USE_ALT_HEADER', '\\"foo_alt.h\\"')])

:Changed in version 4.5: SCons no longer sorts $CPPDEFINES values
entered in dictionary form. Python now preserves dictionary keys
in the order they are entered, so it is no longer necessary to
sort them to ensure a stable command line.

CPPDEFPREFIX
The prefix used to specify preprocessor macro definitions on the
C compiler command line. This will be prepended to each
definition in the $CPPDEFINES construction variable when the
$_CPPDEFFLAGS variable is automatically generated.

CPPDEFSUFFIX
The suffix used to specify preprocessor macro definitions on the
C compiler command line. This will be appended to each definition
in the $CPPDEFINES construction variable when the $_CPPDEFFLAGS
variable is automatically generated.

CPPFLAGS
User-specified C preprocessor options. These will be included in
any command that uses the C preprocessor, including not just
compilation of C and C++ source files via the $CCCOM, $SHCCCOM,
$CXXCOM and $SHCXXCOM command lines, but also the $FORTRANPPCOM,
$SHFORTRANPPCOM, $F77PPCOM and $SHF77PPCOM command lines used to
compile a Fortran source file, and the $ASPPCOM command line used
to assemble an assembly language source file, after first running
each file through the C preprocessor. Note that this variable
does not contain -I (or similar) include search path options that
scons generates automatically from $CPPPATH. See $_CPPINCFLAGS,
below, for the variable that expands to those options.

_CPPINCFLAGS
An automatically-generated construction variable containing the C
preprocessor command-line options for specifying directories to
be searched for include files. The value of $_CPPINCFLAGS is
created by respectively prepending and appending $INCPREFIX and
$INCSUFFIX to each directory in $CPPPATH.

CPPPATH
The list of directories that the C preprocessor will search for
include directories. The C/C++ implicit dependency scanner will
search these directories for include files. In general, it's not
advised to put include directory directives directly into
$CCFLAGS or $CXXFLAGS as the result will be non-portable and the
directories will not be searched by the dependency scanner.
$CPPPATH should be a list of path strings, or a single string,
not a pathname list joined by Python's os.pathsep.

Note: directory names in $CPPPATH will be looked-up relative to
the directory of the SConscript file when they are used in a
command. To force scons to lookup a directory relative to the
root of the source tree, use the # prefix:

env = Environment(CPPPATH='#/include')

The directory lookup can also be forced using the Dir function:

include = Dir('include')
env = Environment(CPPPATH=include)

The directory list will be added to command lines through the
automatically-generated $_CPPINCFLAGS construction variable,
which is constructed by respectively prepending and appending the
values of the $INCPREFIX and $INCSUFFIX construction variables to
each directory in $CPPPATH. Any command lines you define that
need the $CPPPATH directory list should include $_CPPINCFLAGS:

env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

CPPSUFFIXES
The list of suffixes of files that will be scanned for C
preprocessor implicit dependencies (#include lines). The default
list is:

[".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
".h", ".H", ".hxx", ".hpp", ".hh",
".F", ".fpp", ".FPP",
".m", ".mm",
".S", ".spp", ".SPP"]

CXX
The C++ compiler. See also $SHCXX for compiling to shared
objects.

CXXCOM
The command line used to compile a C++ source file to an object
file. Any options specified in the $CXXFLAGS and $CPPFLAGS
construction variables are included on this command line. See
also $SHCXXCOM for compiling to shared objects.

CXXCOMSTR
If set, the string displayed when a C++ source file is compiled
to a (static) object file. If not set, then $CXXCOM (the command
line) is displayed. See also $SHCXXCOMSTR for compiling to shared
objects.

env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

CXXFILESUFFIX
The suffix for C++ source files. This is used by the internal
CXXFile builder when generating C++ files from Lex (.ll) or YACC
(.yy) input files. The default suffix is .cc. SCons also treats
files with the suffixes .cpp, .cxx, .c++, and .C++ as C++ files,
and files with .mm suffixes as Objective-C++ files. On
case-sensitive systems (Linux, UNIX, and other POSIX-alikes),
SCons also treats .C (upper case) files as C++ files.

CXXFLAGS
General options that are passed to the C++ compiler. By default,
this includes the value of $CCFLAGS, so that setting $CCFLAGS
affects both C and C++ compilation. If you want to add
C++-specific flags, you must set or override the value of
$CXXFLAGS. See also $SHCXXFLAGS for compiling to shared objects.

CXXVERSION
The version number of the C++ compiler. This may or may not be
set, depending on the specific C++ compiler being used.

DC
The D compiler to use. See also $SHDC for compiling to shared
objects.

DCOM
The command line used to compile a D file to an object file. Any
options specified in the $DFLAGS construction variable is
included on this command line. See also $SHDCOM for compiling to
shared objects.

DCOMSTR
If set, the string displayed when a D source file is compiled to
a (static) object file. If not set, then $DCOM (the command line)
is displayed. See also $SHDCOMSTR for compiling to shared
objects.

DDEBUG
List of debug tags to enable when compiling.

DDEBUGPREFIX
DDEBUGPREFIX.

DDEBUGSUFFIX
DDEBUGSUFFIX.

DESCRIPTION
A long description of the project being packaged. This is
included in the relevant section of the file that controls the
packaging build.

See the Package builder.

DESCRIPTION_lang
A language-specific long description for the specified lang. This
is used to populate a %description -l section of an RPM .spec
file.

See the Package builder.

DFILESUFFIX
DFILESUFFIX.

DFLAGPREFIX
DFLAGPREFIX.

DFLAGS
General options that are passed to the D compiler.

DFLAGSUFFIX
DFLAGSUFFIX.

DI_FILE_DIR
Path where .di files will be generated

DI_FILE_DIR_PREFIX
Prefix to send the di path argument to compiler

DI_FILE_DIR_SUFFFIX
Suffix to send the di path argument to compiler

DI_FILE_SUFFIX
Suffix of d include files default is .di

DINCPREFIX
DINCPREFIX.

DINCSUFFIX
DLIBFLAGSUFFIX.

Dir
A function that converts a string into a Dir instance relative to
the target being built.

Dirs
A function that converts a list of strings into a list of Dir
instances relative to the target being built.

DLIB
Name of the lib tool to use for D codes.

DLIBCOM
The command line to use when creating libraries.

DLIBDIRPREFIX
DLIBLINKPREFIX.

DLIBDIRSUFFIX
DLIBLINKSUFFIX.

DLIBFLAGPREFIX
DLIBFLAGPREFIX.

DLIBFLAGSUFFIX
DLIBFLAGSUFFIX.

DLIBLINKPREFIX
DLIBLINKPREFIX.

DLIBLINKSUFFIX
DLIBLINKSUFFIX.

DLINK
Name of the linker to use for linking systems including D
sources. See also $SHDLINK for linking shared objects.

DLINKCOM
The command line to use when linking systems including D sources.
See also $SHDLINKCOM for linking shared objects.

DLINKFLAGPREFIX
DLINKFLAGPREFIX.

DLINKFLAGS
List of linker flags. See also $SHDLINKFLAGS for linking shared
objects.

DLINKFLAGSUFFIX
DLINKFLAGSUFFIX.

DOCBOOK_DEFAULT_XSL_EPUB
The default XSLT file for the DocbookEpub builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTML
The default XSLT file for the DocbookHtml builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
The default XSLT file for the DocbookHtmlChunked builder within
the current environment, if no other XSLT gets specified via
keyword.

DOCBOOK_DEFAULT_XSL_HTMLHELP
The default XSLT file for the DocbookHtmlhelp builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_MAN
The default XSLT file for the DocbookMan builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_PDF
The default XSLT file for the DocbookPdf builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_SLIDESHTML
The default XSLT file for the DocbookSlidesHtml builder within
the current environment, if no other XSLT gets specified via
keyword.

DOCBOOK_DEFAULT_XSL_SLIDESPDF
The default XSLT file for the DocbookSlidesPdf builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_FOP
The path to the PDF renderer fop or xep, if one of them is
installed (fop gets checked first).

DOCBOOK_FOPCOM
The full command-line for the PDF renderer fop or xep.

DOCBOOK_FOPCOMSTR
The string displayed when a renderer like fop or xep is used to
create PDF output from an XML file.

DOCBOOK_FOPFLAGS
Additional command-line flags for the PDF renderer fop or xep.

DOCBOOK_XMLLINT
The path to the external executable xmllint, if it's installed.
Note, that this is only used as last fallback for resolving
XIncludes, if no lxml Python binding can be imported in the
current system.

DOCBOOK_XMLLINTCOM
The full command-line for the external executable xmllint.

DOCBOOK_XMLLINTCOMSTR
The string displayed when xmllint is used to resolve XIncludes
for a given XML file.

DOCBOOK_XMLLINTFLAGS
Additional command-line flags for the external executable
xmllint.

DOCBOOK_XSLTPROC
The path to the external executable xsltproc (or saxon, xalan),
if one of them is installed. Note, that this is only used as last
fallback for XSL transformations, if no lxml Python binding can
be imported in the current system.

DOCBOOK_XSLTPROCCOM
The full command-line for the external executable xsltproc (or
saxon, xalan).

DOCBOOK_XSLTPROCCOMSTR
The string displayed when xsltproc is used to transform an XML
file via a given XSLT stylesheet.

DOCBOOK_XSLTPROCFLAGS
Additional command-line flags for the external executable
xsltproc (or saxon, xalan).

DOCBOOK_XSLTPROCPARAMS
Additional parameters that are not intended for the XSLT
processor executable, but the XSL processing itself. By default,
they get appended at the end of the command line for saxon and
saxon-xslt, respectively.

DPATH
List of paths to search for import modules.

DRPATHPREFIX
DRPATHPREFIX.

DRPATHSUFFIX
DRPATHSUFFIX.

DSUFFIXES
The list of suffixes of files that will be scanned for imported D
package files. The default list is ['.d'].

DVERPREFIX
DVERPREFIX.

DVERSIONS
List of version tags to enable when compiling.

DVERSUFFIX
DVERSUFFIX.

DVIPDF
The TeX DVI file to PDF file converter.

DVIPDFCOM
The command line used to convert TeX DVI files into a PDF file.

DVIPDFCOMSTR
The string displayed when a TeX DVI file is converted into a PDF
file. If this is not set, then $DVIPDFCOM (the command line) is
displayed.

DVIPDFFLAGS
General options passed to the TeX DVI file to PDF file converter.

DVIPS
The TeX DVI file to PostScript converter.

DVIPSFLAGS
General options passed to the TeX DVI file to PostScript
converter.

ENV
The execution environment - a dictionary of environment variables
used when SCons invokes external commands to build targets
defined in this construction environment. When $ENV is passed to
a command, all list values are assumed to be path lists and are
joined using the search path separator. Any other non-string
values are coerced to a string.

Note that by default SCons does not propagate the environment in
effect when you execute scons (the "shell environment") to the
execution environment. This is so that builds will be guaranteed
repeatable regardless of the environment variables set at the
time scons is invoked. If you want to propagate a shell
environment variable to the commands executed to build target
files, you must do so explicitly. A common example is the system
PATH environment variable, so that scons will find utilities the
same way as the invoking shell (or other process):

import os
env = Environment(ENV={'PATH': os.environ['PATH']})

Although it is usually not recommended, you can propagate the
entire shell environment in one go:

import os
env = Environment(ENV=os.environ.copy())

ESCAPE
A function that will be called to escape shell special characters
in command lines. The function should take one argument: the
command line string to escape; and should return the escaped
command line.

F03
The Fortran 03 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F03 if you need to use a
specific compiler or compiler version for Fortran 03 files.

F03COM
The command line used to compile a Fortran 03 source file to an
object file. You only need to set $F03COM if you need to use a
specific command line for Fortran 03 files. You should normally
set the $FORTRANCOM variable, which specifies the default command
line for all Fortran versions.

F03COMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to an object file. If not set, then $F03COM or
$FORTRANCOM (the command line) is displayed.

F03FILESUFFIXES
The list of file extensions for which the F03 dialect will be
used. By default, this is ['.f03']

F03FLAGS
General user-specified options that are passed to the Fortran 03
compiler. Note that this variable does not contain -I (or
similar) include search path options that scons generates
automatically from $F03PATH. See $_F03INCFLAGS below, for the
variable that expands to those options. You only need to set
$F03FLAGS if you need to define specific user options for Fortran
03 files. You should normally set the $FORTRANFLAGS variable,
which specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

_F03INCFLAGS
An automatically-generated construction variable containing the
Fortran 03 compiler command-line options for specifying
directories to be searched for include files. The value of
$_F03INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX
to the beginning and end of each directory in $F03PATH.

F03PATH
The list of directories that the Fortran 03 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F03FLAGS because the result will
be non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F03PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to lookup a directory relative to
the root of the source tree, use #: You only need to set $F03PATH
if you need to define a specific include path for Fortran 03
files. You should normally set the $FORTRANPATH variable, which
specifies the include path for the default Fortran compiler for
all Fortran versions.

env = Environment(F03PATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F03PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F03INCFLAGS construction variable,
which is constructed by appending the values of the $INCPREFIX
and $INCSUFFIX construction variables to the beginning and end of
each directory in $F03PATH. Any command lines you define that
need the F03PATH directory list should include $_F03INCFLAGS:

env = Environment(F03COM="my_compiler $_F03INCFLAGS -c -o $TARGET $SOURCE")

F03PPCOM
The command line used to compile a Fortran 03 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F03FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $F03PPCOM if you need to use a
specific C-preprocessor command line for Fortran 03 files. You
should normally set the $FORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

F03PPCOMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to an object file after first running the file through
the C preprocessor. If not set, then $F03PPCOM or $FORTRANPPCOM
(the command line) is displayed.

F03PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F03 dialect will be used. By default, this
is empty.

F08
The Fortran 08 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F08 if you need to use a
specific compiler or compiler version for Fortran 08 files.

F08COM
The command line used to compile a Fortran 08 source file to an
object file. You only need to set $F08COM if you need to use a
specific command line for Fortran 08 files. You should normally
set the $FORTRANCOM variable, which specifies the default command
line for all Fortran versions.

F08COMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to an object file. If not set, then $F08COM or
$FORTRANCOM (the command line) is displayed.

F08FILESUFFIXES
The list of file extensions for which the F08 dialect will be
used. By default, this is ['.f08']

F08FLAGS
General user-specified options that are passed to the Fortran 08
compiler. Note that this variable does not contain -I (or
similar) include search path options that scons generates
automatically from $F08PATH. See $_F08INCFLAGS below, for the
variable that expands to those options. You only need to set
$F08FLAGS if you need to define specific user options for Fortran
08 files. You should normally set the $FORTRANFLAGS variable,
which specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

_F08INCFLAGS
An automatically-generated construction variable containing the
Fortran 08 compiler command-line options for specifying
directories to be searched for include files. The value of
$_F08INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX
to the beginning and end of each directory in $F08PATH.

F08PATH
The list of directories that the Fortran 08 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F08FLAGS because the result will
be non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F08PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to lookup a directory relative to
the root of the source tree, use #: You only need to set $F08PATH
if you need to define a specific include path for Fortran 08
files. You should normally set the $FORTRANPATH variable, which
specifies the include path for the default Fortran compiler for
all Fortran versions.

env = Environment(F08PATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F08PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F08INCFLAGS construction variable,
which is constructed by appending the values of the $INCPREFIX
and $INCSUFFIX construction variables to the beginning and end of
each directory in $F08PATH. Any command lines you define that
need the F08PATH directory list should include $_F08INCFLAGS:

env = Environment(F08COM="my_compiler $_F08INCFLAGS -c -o $TARGET $SOURCE")

F08PPCOM
The command line used to compile a Fortran 08 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F08FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $F08PPCOM if you need to use a
specific C-preprocessor command line for Fortran 08 files. You
should normally set the $FORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

F08PPCOMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to an object file after first running the file through
the C preprocessor. If not set, then $F08PPCOM or $FORTRANPPCOM
(the command line) is displayed.

F08PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F08 dialect will be used. By default, this
is empty.

F77
The Fortran 77 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F77 if you need to use a
specific compiler or compiler version for Fortran 77 files.

F77COM
The command line used to compile a Fortran 77 source file to an
object file. You only need to set $F77COM if you need to use a
specific command line for Fortran 77 files. You should normally
set the $FORTRANCOM variable, which specifies the default command
line for all Fortran versions.

F77COMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to an object file. If not set, then $F77COM or
$FORTRANCOM (the command line) is displayed.

F77FILESUFFIXES
The list of file extensions for which the F77 dialect will be
used. By default, this is ['.f77']

F77FLAGS
General user-specified options that are passed to the Fortran 77
compiler. Note that this variable does not contain -I (or
similar) include search path options that scons generates
automatically from $F77PATH. See $_F77INCFLAGS below, for the
variable that expands to those options. You only need to set
$F77FLAGS if you need to define specific user options for Fortran
77 files. You should normally set the $FORTRANFLAGS variable,
which specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

_F77INCFLAGS
An automatically-generated construction variable containing the
Fortran 77 compiler command-line options for specifying
directories to be searched for include files. The value of
$_F77INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX
to the beginning and end of each directory in $F77PATH.

F77PATH
The list of directories that the Fortran 77 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F77FLAGS because the result will
be non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F77PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to lookup a directory relative to
the root of the source tree, use #: You only need to set $F77PATH
if you need to define a specific include path for Fortran 77
files. You should normally set the $FORTRANPATH variable, which
specifies the include path for the default Fortran compiler for
all Fortran versions.

env = Environment(F77PATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F77PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F77INCFLAGS construction variable,
which is constructed by appending the values of the $INCPREFIX
and $INCSUFFIX construction variables to the beginning and end of
each directory in $F77PATH. Any command lines you define that
need the F77PATH directory list should include $_F77INCFLAGS:

env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

F77PPCOM
The command line used to compile a Fortran 77 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F77FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $F77PPCOM if you need to use a
specific C-preprocessor command line for Fortran 77 files. You
should normally set the $FORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

F77PPCOMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to an object file after first running the file through
the C preprocessor. If not set, then $F77PPCOM or $FORTRANPPCOM
(the command line) is displayed.

F77PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F77 dialect will be used. By default, this
is empty.

F90
The Fortran 90 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F90 if you need to use a
specific compiler or compiler version for Fortran 90 files.

F90COM
The command line used to compile a Fortran 90 source file to an
object file. You only need to set $F90COM if you need to use a
specific command line for Fortran 90 files. You should normally
set the $FORTRANCOM variable, which specifies the default command
line for all Fortran versions.

F90COMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to an object file. If not set, then $F90COM or
$FORTRANCOM (the command line) is displayed.

F90FILESUFFIXES
The list of file extensions for which the F90 dialect will be
used. By default, this is ['.f90']

F90FLAGS
General user-specified options that are passed to the Fortran 90
compiler. Note that this variable does not contain -I (or
similar) include search path options that scons generates
automatically from $F90PATH. See $_F90INCFLAGS below, for the
variable that expands to those options. You only need to set
$F90FLAGS if you need to define specific user options for Fortran
90 files. You should normally set the $FORTRANFLAGS variable,
which specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

_F90INCFLAGS
An automatically-generated construction variable containing the
Fortran 90 compiler command-line options for specifying
directories to be searched for include files. The value of
$_F90INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX
to the beginning and end of each directory in $F90PATH.

F90PATH
The list of directories that the Fortran 90 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F90FLAGS because the result will
be non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F90PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to lookup a directory relative to
the root of the source tree, use #: You only need to set $F90PATH
if you need to define a specific include path for Fortran 90
files. You should normally set the $FORTRANPATH variable, which
specifies the include path for the default Fortran compiler for
all Fortran versions.

env = Environment(F90PATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F90PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F90INCFLAGS construction variable,
which is constructed by appending the values of the $INCPREFIX
and $INCSUFFIX construction variables to the beginning and end of
each directory in $F90PATH. Any command lines you define that
need the F90PATH directory list should include $_F90INCFLAGS:

env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

F90PPCOM
The command line used to compile a Fortran 90 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F90FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $F90PPCOM if you need to use a
specific C-preprocessor command line for Fortran 90 files. You
should normally set the $FORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

F90PPCOMSTR
If set, the string displayed when a Fortran 90 source file is
compiled after first running the file through the C preprocessor.
If not set, then $F90PPCOM or $FORTRANPPCOM (the command line) is
displayed.

F90PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F90 dialect will be used. By default, this
is empty.

F95
The Fortran 95 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F95 if you need to use a
specific compiler or compiler version for Fortran 95 files.

F95COM
The command line used to compile a Fortran 95 source file to an
object file. You only need to set $F95COM if you need to use a
specific command line for Fortran 95 files. You should normally
set the $FORTRANCOM variable, which specifies the default command
line for all Fortran versions.

F95COMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to an object file. If not set, then $F95COM or
$FORTRANCOM (the command line) is displayed.

F95FILESUFFIXES
The list of file extensions for which the F95 dialect will be
used. By default, this is ['.f95']

F95FLAGS
General user-specified options that are passed to the Fortran 95
compiler. Note that this variable does not contain -I (or
similar) include search path options that scons generates
automatically from $F95PATH. See $_F95INCFLAGS below, for the
variable that expands to those options. You only need to set
$F95FLAGS if you need to define specific user options for Fortran
95 files. You should normally set the $FORTRANFLAGS variable,
which specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

_F95INCFLAGS
An automatically-generated construction variable containing the
Fortran 95 compiler command-line options for specifying
directories to be searched for include files. The value of
$_F95INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX
to the beginning and end of each directory in $F95PATH.

F95PATH
The list of directories that the Fortran 95 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F95FLAGS because the result will
be non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F95PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to lookup a directory relative to
the root of the source tree, use #: You only need to set $F95PATH
if you need to define a specific include path for Fortran 95
files. You should normally set the $FORTRANPATH variable, which
specifies the include path for the default Fortran compiler for
all Fortran versions.

env = Environment(F95PATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F95PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F95INCFLAGS construction variable,
which is constructed by appending the values of the $INCPREFIX
and $INCSUFFIX construction variables to the beginning and end of
each directory in $F95PATH. Any command lines you define that
need the F95PATH directory list should include $_F95INCFLAGS:

env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

F95PPCOM
The command line used to compile a Fortran 95 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F95FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $F95PPCOM if you need to use a
specific C-preprocessor command line for Fortran 95 files. You
should normally set the $FORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

F95PPCOMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to an object file after first running the file through
the C preprocessor. If not set, then $F95PPCOM or $FORTRANPPCOM
(the command line) is displayed.

F95PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F95 dialect will be used. By default, this
is empty.

File
A function that converts a string into a File instance relative
to the target being built.

FILE_ENCODING
File encoding used for files written by Textfile and Substfile.
Set to "utf-8" by default.


New in version 4.5.0.

FORTRAN
The default Fortran compiler for all versions of Fortran.

FORTRANCOM
The command line used to compile a Fortran source file to an
object file. By default, any options specified in the
$FORTRANFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS
construction variables are included on this command line.

FORTRANCOMMONFLAGS
General user-specified options that are passed to the Fortran
compiler. Similar to $FORTRANFLAGS, but this construction
variable is applied to all dialects.

New in version 4.4.

FORTRANCOMSTR
If set, the string displayed when a Fortran source file is
compiled to an object file. If not set, then $FORTRANCOM (the
command line) is displayed.

FORTRANFILESUFFIXES
The list of file extensions for which the FORTRAN dialect will be
used. By default, this is ['.f', '.for', '.ftn']

FORTRANFLAGS
General user-specified options for the FORTRAN dialect that are
passed to the Fortran compiler. Note that this variable does not
contain -I (or similar) include or module search path options
that scons generates automatically from $FORTRANPATH. See
$_FORTRANINCFLAGS and $_FORTRANMODFLAG for the construction
variables that expand those options.

_FORTRANINCFLAGS
An automatically-generated construction variable containing the
Fortran compiler command-line options for specifying directories
to be searched for include files and module files. The value of
$_FORTRANINCFLAGS is created by respectively prepending and
appending $INCPREFIX and $INCSUFFIX to the beginning and end of
each directory in $FORTRANPATH.

FORTRANMODDIR
Directory location where the Fortran compiler should place any
module files it generates. This variable is empty, by default.
Some Fortran compilers will internally append this directory in
the search path for module files, as well.

FORTRANMODDIRPREFIX
The prefix used to specify a module directory on the Fortran
compiler command line. This will be prepended to the beginning of
the directory in the $FORTRANMODDIR construction variables when
the $_FORTRANMODFLAG variables is automatically generated.

FORTRANMODDIRSUFFIX
The suffix used to specify a module directory on the Fortran
compiler command line. This will be appended to the end of the
directory in the $FORTRANMODDIR construction variables when the
$_FORTRANMODFLAG variables is automatically generated.

_FORTRANMODFLAG
An automatically-generated construction variable containing the
Fortran compiler command-line option for specifying the directory
location where the Fortran compiler should place any module files
that happen to get generated during compilation. The value of
$_FORTRANMODFLAG is created by respectively prepending and
appending $FORTRANMODDIRPREFIX and $FORTRANMODDIRSUFFIX to the
beginning and end of the directory in $FORTRANMODDIR.

FORTRANMODPREFIX
The module file prefix used by the Fortran compiler. SCons
assumes that the Fortran compiler follows the quasi-standard
naming convention for module files of module_name.mod. As a
result, this variable is left empty, by default. For situations
in which the compiler does not necessarily follow the normal
convention, the user may use this variable. Its value will be
appended to every module file name as scons attempts to resolve
dependencies.

FORTRANMODSUFFIX
The module file suffix used by the Fortran compiler. SCons
assumes that the Fortran compiler follows the quasi-standard
naming convention for module files of module_name.mod. As a
result, this variable is set to ".mod", by default. For
situations in which the compiler does not necessarily follow the
normal convention, the user may use this variable. Its value will
be appended to every module file name as scons attempts to
resolve dependencies.

FORTRANPATH
The list of directories that the Fortran compiler will search for
include files and (for some compilers) module files. The Fortran
implicit dependency scanner will search these directories for
include files (but not module files since they are autogenerated
and, as such, may not actually exist at the time the scan takes
place). Don't explicitly put include directory arguments in
FORTRANFLAGS because the result will be non-portable and the
directories will not be searched by the dependency scanner. Note:
directory names in FORTRANPATH will be looked-up relative to the
SConscript directory when they are used in a command. To force
scons to lookup a directory relative to the root of the source
tree, use #:

env = Environment(FORTRANPATH='#/include')

The directory look-up can also be forced using the Dir()
function:

include = Dir('include')
env = Environment(FORTRANPATH=include)

The directory list will be added to command lines through the
automatically-generated $_FORTRANINCFLAGS construction variable,
which is constructed by respectively prepending and appending the
values of the $INCPREFIX and $INCSUFFIX construction variables to
the beginning and end of each directory in $FORTRANPATH. Any
command lines you define that need the FORTRANPATH directory list
should include $_FORTRANINCFLAGS:

env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

FORTRANPPCOM
The command line used to compile a Fortran source file to an
object file after first running the file through the C
preprocessor. By default, any options specified in the
$FORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and
$_FORTRANINCFLAGS construction variables are included on this
command line.

FORTRANPPCOMSTR
If set, the string displayed when a Fortran source file is
compiled to an object file after first running the file through
the C preprocessor. If not set, then $FORTRANPPCOM (the command
line) is displayed.

FORTRANPPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for FORTRAN dialect will be used. By default,
this is ['.fpp', '.FPP']

FORTRANSUFFIXES
The list of suffixes of files that will be scanned for Fortran
implicit dependencies (INCLUDE lines and USE statements). The
default list is:

[".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

FRAMEWORKPATH
On Mac OS X with gcc, a list containing the paths to search for
frameworks. Used by the compiler to find framework-style includes
like #include <Fmwk/Header.h>. Used by the linker to find
user-specified frameworks when linking (see $FRAMEWORKS). For
example:

env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')


will add

... -Fmyframeworkdir


to the compiler and linker command lines.

_FRAMEWORKPATH
On Mac OS X with gcc, an automatically-generated construction
variable containing the linker command-line options corresponding
to $FRAMEWORKPATH.

FRAMEWORKPATHPREFIX
On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH
entries. (see $FRAMEWORKPATH). The default value is -F.

FRAMEWORKPREFIX
On Mac OS X with gcc, the prefix to be used for linking in
frameworks (see $FRAMEWORKS). The default value is -framework.

FRAMEWORKS
On Mac OS X with gcc, a list of the framework names to be linked
into a program or shared library or bundle. The default value is
the empty list. For example:

env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))


_FRAMEWORKS
On Mac OS X with gcc, an automatically-generated construction
variable containing the linker command-line options for linking
with FRAMEWORKS.

FRAMEWORKSFLAGS
On Mac OS X with gcc, general user-supplied frameworks options to
be added at the end of a command line building a loadable module.
(This has been largely superseded by the $FRAMEWORKPATH,
$FRAMEWORKPATHPREFIX, $FRAMEWORKPREFIX and $FRAMEWORKS variables
described above.)

GS
The Ghostscript program used to, for example, convert PostScript
to PDF files.

GSCOM
The full Ghostscript command line used for the conversion
process. Its default value is "$GS $GSFLAGS -sOutputFile=$TARGET
$SOURCES".

GSCOMSTR
The string displayed when Ghostscript is called for the
conversion process. If this is not set (the default), then $GSCOM
(the command line) is displayed.

GSFLAGS
General options passed to the Ghostscript program, when
converting PostScript to PDF files for example. Its default value
is "-dNOPAUSE -dBATCH -sDEVICE=pdfwrite"

HOST_ARCH
The name of the host hardware architecture used to create this
construction environment. The platform code sets this when
initializing (see $PLATFORM and the platform argument to
Environment). Note the detected name of the architecture may not
be identical to that returned by the Python platform.machine
method.

On the win32 platform, if the Microsoft Visual C++ compiler is
available, msvc tool setup is done using $HOST_ARCH and
$TARGET_ARCH. Changing the values at any later time will not
cause the tool to be reinitialized. Valid host arch values are
x86 and arm for 32-bit hosts and amd64, arm64, and x86_64 for
64-bit hosts.

Should be considered immutable. $HOST_ARCH is not currently used
by other platforms, but the option is reserved to do so in future

HOST_OS
The name of the host operating system for the platform used to
create this construction environment. The platform code sets this
when initializing (see $PLATFORM and the platform argument to
Environment).

Should be considered immutable. $HOST_OS is not currently used
by SCons, but the option is reserved to do so in future

IDLSUFFIXES
The list of suffixes of files that will be scanned for IDL
implicit dependencies (#include or import lines). The default
list is:

[".idl", ".IDL"]

IMPLIBNOVERSIONSYMLINKS
Used to override
$SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS when creating
versioned import library for a shared library/loadable module. If
not defined, then
$SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS is used to
determine whether to disable symlink generation or not.

IMPLIBPREFIX
The prefix used for import library names. For example, cygwin
uses import libraries (libfoo.dll.a) in pair with dynamic
libraries (cygfoo.dll). The cyglink linker sets $IMPLIBPREFIX to
'lib' and $SHLIBPREFIX to 'cyg'.

IMPLIBSUFFIX
The suffix used for import library names. For example, cygwin
uses import libraries (libfoo.dll.a) in pair with dynamic
libraries (cygfoo.dll). The cyglink linker sets $IMPLIBSUFFIX to
'.dll.a' and $SHLIBSUFFIX to '.dll'.

IMPLIBVERSION
Used to override $SHLIBVERSION/$LDMODULEVERSION when generating
versioned import library for a shared library/loadable module. If
undefined, the $SHLIBVERSION/$LDMODULEVERSION is used to
determine the version of versioned import library.

IMPLICIT_COMMAND_DEPENDENCIES
Controls whether or not SCons will add implicit dependencies for
the commands executed to build targets.

By default, SCons will add to each target an implicit dependency
on the command represented by the first argument of any command
line it executes (which is typically the command itself). By
setting such a dependency, SCons can determine that a target
should be rebuilt if the command changes, such as when a compiler
is upgraded to a new version. The specific file for the
dependency is found by searching the PATH variable in the ENV
dictionary in the construction environment used to execute the
command. The default is the same as setting the construction
variable $IMPLICIT_COMMAND_DEPENDENCIES to a True-like value
("true", "yes", or "1" - but not a number greater than one, as
that has a different meaning).

Action strings can be segmented by the use of an AND operator,
&&. In a segmented string, each segment is a separate "command
line", these are run sequentially until one fails, or the entire
sequence has been executed. If an action string is segmented,
then the selected behavior of $IMPLICIT_COMMAND_DEPENDENCIES is
applied to each segment.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to a False-like value
("none", "false", "no", "0", etc.), then the implicit dependency
will not be added to the targets built with that construction
environment.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to "2" or higher, then
that number of arguments in the command line will be scanned for
relative or absolute paths. If any are present, they will be
added as implicit dependencies to the targets built with that
construction environment. The first argument in the command line
will be searched for using the PATH variable in the ENV
dictionary in the construction environment used to execute the
command. The other arguments will only be found if they are
absolute paths or valid paths relative to the working directory.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to "all", then all
arguments in the command line will be scanned for relative or
absolute paths. If any are present, they will be added as
implicit dependencies to the targets built with that construction
environment. The first argument in the command line will be
searched for using the PATH variable in the ENV dictionary in the
construction environment used to execute the command. The other
arguments will only be found if they are absolute paths or valid
paths relative to the working directory.

env = Environment(IMPLICIT_COMMAND_DEPENDENCIES=False)

INCPREFIX
The prefix used to specify an include directory on the C compiler
command line. This will be prepended to each directory in the
$CPPPATH and $FORTRANPATH construction variables when the
$_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically
generated.

INCSUFFIX
The suffix used to specify an include directory on the C compiler
command line. This will be appended to each directory in the
$CPPPATH and $FORTRANPATH construction variables when the
$_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically
generated.

INSTALL
A function to be called to install a file into a destination file
name. The default function copies the file into the destination
(and sets the destination file's mode and permission bits to
match the source file's). The function takes the following
arguments:

def install(dest, source, env):


dest is the path name of the destination file. source is the
path name of the source file. env is the construction
environment (a dictionary of construction values) in force for
this file installation.

INSTALLSTR
The string displayed when a file is installed into a destination
file name. The default is:

Install file: "$SOURCE" as "$TARGET"

INTEL_C_COMPILER_VERSION
Set by the intelc Tool to the major version number of the Intel C
compiler selected for use.

JAR
The Java archive tool.

JARCHDIR
The directory to which the Java archive tool should change (using
the -C option).

JARCOM
The command line used to call the Java archive tool.

JARCOMSTR
The string displayed when the Java archive tool is called If this
is not set, then $JARCOM (the command line) is displayed.

env = Environment(JARCOMSTR="JARchiving $SOURCES into $TARGET")

JARFLAGS
General options passed to the Java archive tool. By default, this
is set to cf to create the necessary jar file.

JARSUFFIX
The suffix for Java archives: .jar by default.

JAVABOOTCLASSPATH
Specifies the location of the bootstrap class files. Can be
specified as a string or Node object, or as a list of strings or
Node objects.

The value will be added to the JDK command lines via the
-bootclasspath option, which requires a system-specific search
path separator. This will be supplied by SCons as needed when it
constructs the command line if $JAVABOOTCLASSPATH is provided in
list form. If $JAVABOOTCLASSPATH is a single string containing
search path separator characters (: for POSIX systems or ; for
Windows), it will not be modified; and so is inherently
system-specific; to supply the path in a system-independent
manner, give $JAVABOOTCLASSPATH as a list of paths instead.

Note
Can only be used when compiling for releases prior to JDK 9.

JAVAC
The Java compiler.

JAVACCOM
The command line used to compile a directory tree containing Java
source files to corresponding Java class files. Any options
specified in the $JAVACFLAGS construction variable are included
on this command line.

JAVACCOMSTR
The string displayed when compiling a directory tree of Java
source files to corresponding Java class files. If this is not
set, then $JAVACCOM (the command line) is displayed.

env = Environment(JAVACCOMSTR="Compiling class files $TARGETS from $SOURCES")


JAVACFLAGS
General options that are passed to the Java compiler.

JAVACLASSDIR
The directory in which Java class files may be found. This is
stripped from the beginning of any Java .class file names
supplied to the JavaH builder.

JAVACLASSPATH
Specifies the class search path for the JDK tools. Can be
specified as a string or Node object, or as a list of strings or
Node objects. Class path entries may be directory names to search
for class files or packages, pathnames to archives (.jar or .zip)
containing classes, or paths ending in a "base name wildcard"
character (*), which matches files in that directory with a .jar
suffix. See the Java documentation for more details.

The value will be added to the JDK command lines via the
-classpath option, which requires a system-specific search path
separator. This will be supplied by SCons as needed when it
constructs the command line if $JAVACLASSPATH is provided in list
form. If $JAVACLASSPATH is a single string containing search path
separator characters (: for POSIX systems or ; for Windows), it
will be split on the separator into a list of individual paths
for dependency scanning purposes. It will not be modified for JDK
command-line usage, so such a string is inherently
system-specific; to supply the path in a system-independent
manner, give $JAVACLASSPATH as a list of paths instead.

Note

SCons always supplies a -sourcepath when invoking the Java
compiler javac, regardless of the setting of $JAVASOURCEPATH,
as it passes the path(s) to the source(s) supplied in the
call to the Java builder via -sourcepath . From the
documentation of the standard Java toolkit for javac: "If not
compiling code for modules, if the --source-path or
-sourcepath option is not specified, then the user class path
is also searched for source files." Since -sourcepath is
always supplied, javac will not use the contents of the value
of $JAVACLASSPATH when searching for sources.

JAVACLASSSUFFIX
The suffix for Java class files; .class by default.

JAVAH
The Java generator for C header and stub files.

JAVAHCOM
The command line used to generate C header and stub files from
Java classes. Any options specified in the $JAVAHFLAGS
construction variable are included on this command line.

JAVAHCOMSTR
The string displayed when C header and stub files are generated
from Java classes. If this is not set, then $JAVAHCOM (the
command line) is displayed.

env = Environment(JAVAHCOMSTR="Generating header/stub file(s) $TARGETS from $SOURCES")

JAVAHFLAGS
General options passed to the C header and stub file generator
for Java classes.

JAVAINCLUDES
Include path for Java header files (such as jni.h).

JAVAPROCESSORPATH
Specifies the location of the annotation processor class files.
Can be specified as a string or Node object, or as a list of
strings or Node objects.

The value will be added to the JDK command lines via the
-processorpath option, which requires a system-specific search
path separator. This will be supplied by SCons as needed when it
constructs the command line if $JAVAPROCESSORPATH is provided in
list form. If $JAVAPROCESSORPATH is a single string containing
search path separator characters (: for POSIX systems or ; for
Windows), it will not be modified; and so is inherently
system-specific; to supply the path in a system-independent
manner, give $JAVAPROCESSORPATH as a list of paths instead.


New in version 4.5.0

JAVASOURCEPATH
Specifies the list of directories that will be searched for input
(source) .java files. Can be specified as a string or Node
object, or as a list of strings or Node objects.

The value will be added to the JDK command lines via the
-sourcepath option, which requires a system-specific search path
separator, This will be supplied by SCons as needed when it
constructs the command line if $JAVASOURCEPATH is provided in
list form. If $JAVASOURCEPATH is a single string containing
search path separator characters (: for POSIX systems or ; for
Windows), it will not be modified, and so is inherently
system-specific; to supply the path in a system-independent
manner, give $JAVASOURCEPATH as a list of paths instead.

Note that the specified directories are only added to the command
line via the -sourcepath option. SCons does not currently search
the $JAVASOURCEPATH directories for dependent .java files.

JAVASUFFIX
The suffix for Java files; .java by default.

JAVAVERSION
Specifies the Java version being used by the Java builder. Set
this to specify the version of Java targeted by the javac
compiler. This is sometimes necessary because Java 1.5 changed
the file names that are created for nested anonymous inner
classes, which can cause a mismatch with the files that SCons
expects will be generated by the javac compiler. Setting
$JAVAVERSION to a version greater than 1.4 makes SCons realize
that a build with such a compiler is actually up-to-date. The
default is 1.4.

While this is not primarily intended for selecting one version of
the Java compiler vs. another, it does have that effect on the
Windows platform. A more precise approach is to set $JAVAC (and
related construction variables for related utilities) to the path
to the specific Java compiler you want, if that is not the
default compiler. On non-Windows platforms, the alternatives
system may provide a way to adjust the default Java compiler
without having to specify explicit paths.

LATEX
The LaTeX structured formatter and typesetter.

LATEXCOM
The command line used to call the LaTeX structured formatter and
typesetter.

LATEXCOMSTR
The string displayed when calling the LaTeX structured formatter
and typesetter. If this is not set, then $LATEXCOM (the command
line) is displayed.

env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

LATEXFLAGS
General options passed to the LaTeX structured formatter and
typesetter.

LATEXRETRIES
The maximum number of times that LaTeX will be re-run if the .log
generated by the $LATEXCOM command indicates that there are
undefined references. The default is to try to resolve undefined
references by re-running LaTeX up to three times.

LATEXSUFFIXES
The list of suffixes of files that will be scanned for LaTeX
implicit dependencies (\include or \import files). The default
list is:

[".tex", ".ltx", ".latex"]

LDMODULE
The linker for building loadable modules. By default, this is the
same as $SHLINK.

LDMODULECOM
The command line for building loadable modules. On Mac OS X, this
uses the $LDMODULE, $LDMODULEFLAGS and $FRAMEWORKSFLAGS
variables. On other systems, this is the same as $SHLINK.

LDMODULECOMSTR
If set, the string displayed when building loadable modules. If
not set, then $LDMODULECOM (the command line) is displayed.

LDMODULEEMITTER
Contains the emitter specification for the LoadableModule
builder. The manpage section "Builder Objects" contains general
information on specifying emitters.

LDMODULEFLAGS
General user options passed to the linker for building loadable
modules.

LDMODULENOVERSIONSYMLINKS
Instructs the LoadableModule builder to not automatically create
symlinks for versioned modules. Defaults to
$SHLIBNOVERSIONSYMLINKS

LDMODULEPREFIX
The prefix used for loadable module file names. On Mac OS X, this
is null; on other systems, this is the same as $SHLIBPREFIX.

_LDMODULESONAME
A macro that automatically generates loadable module's SONAME
based on $TARGET, $LDMODULEVERSION and $LDMODULESUFFIX. Used by
LoadableModule builder when the linker tool supports SONAME (e.g.
gnulink).

LDMODULESUFFIX
The suffix used for loadable module file names. On Mac OS X, this
is null; on other systems, this is the same as $SHLIBSUFFIX.

LDMODULEVERSION
When this construction variable is defined, a versioned loadable
module is created by LoadableModule builder. This activates the
$_LDMODULEVERSIONFLAGS and thus modifies the $LDMODULECOM as
required, adds the version number to the library name, and
creates the symlinks that are needed. $LDMODULEVERSION versions
should exist in the same format as $SHLIBVERSION.

_LDMODULEVERSIONFLAGS
This macro automatically introduces extra flags to $LDMODULECOM
when building versioned LoadableModule (that is when
$LDMODULEVERSION is set). _LDMODULEVERSIONFLAGS usually adds
$SHLIBVERSIONFLAGS and some extra dynamically generated options
(such as -Wl,-soname=$_LDMODULESONAME). It is unused by plain
(unversioned) loadable modules.

LDMODULEVERSIONFLAGS
Extra flags added to $LDMODULECOM when building versioned
LoadableModule. These flags are only used when $LDMODULEVERSION
is set.

LEX
The lexical analyzer generator.

LEX_HEADER_FILE
If supplied, generate a C header file with the name taken from
this variable. Will be emitted as a --header-file= command-line
option. Use this in preference to including --header-file= in
$LEXFLAGS directly.

LEX_TABLES_FILE
If supplied, write the lex tables to a file with the name taken
from this variable. Will be emitted as a --tables-file=
command-line option. Use this in preference to including
--tables-file= in $LEXFLAGS directly.

LEXCOM
The command line used to call the lexical analyzer generator to
generate a source file.

LEXCOMSTR
The string displayed when generating a source file using the
lexical analyzer generator. If this is not set, then $LEXCOM (the
command line) is displayed.

env = Environment(LEXCOMSTR="Lex'ing $TARGET from $SOURCES")

LEXFLAGS
General options passed to the lexical analyzer generator. In
addition to passing the value on during invocation, the lex tool
also examines this construction variable for options which cause
additional output files to be generated, and adds those to the
target list. Recognized for this purpose are GNU flex options
--header-file= and --tables-file=; the output file is named by
the option argument.

Note that files specified by --header-file= and --tables-file=
may not be properly handled by SCons in all situations. Consider
using $LEX_HEADER_FILE and $LEX_TABLES_FILE instead.

LEXUNISTD
Used only in Windows environments to set a lex flag to prevent
'unistd.h' from being included. The default value is
'--nounistd'.

_LIBDIRFLAGS
An automatically-generated construction variable containing the
linker command-line options for specifying directories to be
searched for library. The value of $_LIBDIRFLAGS is created by
respectively prepending and appending $LIBDIRPREFIX and
$LIBDIRSUFFIX to each directory in $LIBPATH.

LIBDIRPREFIX
The prefix used to specify a library directory on the linker
command line. This will be prepended to each directory in the
$LIBPATH construction variable when the $_LIBDIRFLAGS variable is
automatically generated.

LIBDIRSUFFIX
The suffix used to specify a library directory on the linker
command line. This will be appended to each directory in the
$LIBPATH construction variable when the $_LIBDIRFLAGS variable is
automatically generated.

LIBEMITTER
Contains the emitter specification for the StaticLibrary builder.
The manpage section "Builder Objects" contains general
information on specifying emitters.

_LIBFLAGS
An automatically-generated construction variable containing the
linker command-line options for specifying libraries to be linked
with the resulting target. The value of $_LIBFLAGS is created by
respectively prepending and appending $LIBLINKPREFIX and
$LIBLINKSUFFIX to each filename in $LIBS.

LIBLINKPREFIX
The prefix used to specify a library to link on the linker
command line. This will be prepended to each library in the $LIBS
construction variable when the $_LIBFLAGS variable is
automatically generated.

LIBLINKSUFFIX
The suffix used to specify a library to link on the linker
command line. This will be appended to each library in the $LIBS
construction variable when the $_LIBFLAGS variable is
automatically generated.

LIBLITERALPREFIX
If the linker supports command line syntax directing that the
argument specifying a library should be searched for literally
(without modification), $LIBLITERALPREFIX can be set to that
indicator. For example, the GNU linker follows this rule: "
-l:foo searches the library path for a filename called foo,
without converting it to libfoo.so or libfoo.a. " If
$LIBLITERALPREFIX is set, SCons will not transform a
string-valued entry in $LIBS that starts with that string. The
entry will still be surrounded with $LIBLINKPREFIX and
$LIBLINKSUFFIX on the command line. This is useful, for example,
in directing that a static library be used when both a static and
dynamic library are available and linker policy is to prefer
dynamic libraries. Compared to the example in $LIBS,

env.Append(LIBS=":libmylib.a")

will let the linker select that specific (static) library name if
found in the library search path. This differs from using a File
object to specify the static library, as the latter bypasses the
library search path entirely.

LIBPATH
The list of directories that will be searched for libraries
specified by the $LIBS construction variable. $LIBPATH should be
a list of path strings, or a single string, not a pathname list
joined by Python's os.pathsep.

Do not put library search directives directly into $LINKFLAGS or
$SHLINKFLAGS as the result will be non-portable.

Note: directory names in $LIBPATH will be looked-up relative to
the directory of the SConscript file when they are used in a
command. To force scons to lookup a directory relative to the
root of the source tree, use the # prefix:

env = Environment(LIBPATH='#/libs')

The directory lookup can also be forced using the Dir function:

libs = Dir('libs')
env = Environment(LIBPATH=libs)

The directory list will be added to command lines through the
automatically-generated $_LIBDIRFLAGS construction variable,
which is constructed by respectively prepending and appending the
values of the $LIBDIRPREFIX and $LIBDIRSUFFIX construction
variables to each directory in $LIBPATH. Any command lines you
define that need the $LIBPATH directory list should include
$_LIBDIRFLAGS:

env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBPREFIX
The prefix used for (static) library file names. A default value
is set for each platform (posix, win32, os2, etc.), but the value
is overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
etc.) to reflect the names of the libraries they create.

LIBPREFIXES
A list of all legal prefixes for library file names on the
current platform. When searching for library dependencies, SCons
will look for files with these prefixes, the base library name,
and suffixes from the $LIBSUFFIXES list.

LIBS
The list of libraries that will be added to the link line for
linking with any executable program, shared library, or loadable
module created by the construction environment or override.

For portability, a string-valued library name should include only
the base library name, without prefixes such as lib or suffixes
such as .so or .dll. SCons will attempt to strip prefixes from
the $LIBPREFIXES list and suffixes from the $LIBSUFFIXES list,
but depending on that behavior will make the build less portable:
for example, on a POSIX system, no attempt will be made to strip
a suffix like .dll. Library name strings in $LIBS should not
include a path component: instead use $LIBPATH to direct the
compiler to look for libraries in those paths, plus any default
paths the linker searches in. If $LIBLITERALPREFIX is set to a
non-empty string, then a string-valued $LIBS entry that starts
with $LIBLITERALPREFIX will cause the rest of the entry to be
searched for unmodified, but respecting normal library search
paths (this is an exception to the guideline above about leaving
off the prefix/suffix from the library name).

If a $LIBS entry is a Node object (either as returned by a
previous Builder call, or as the result of an explicit call to
File), the pathname from that Node will be added to $_LIBFLAGS,
and thus to the link line, unmodified - without adding
$LIBLINKPREFIX or $LIBLINKSUFFIX. Such entries are searched for
literally (including any path component); the library search
paths are not used. For example:

env.Append(LIBS=File('/tmp/mylib.so'))


For each Builder call that causes linking with libraries, SCons
will add the libraries in the setting of $LIBS in effect at that
moment to the dependency graph as dependencies of the target
being generated.

The library list will be transformed to command-line arguments
through the automatically-generated $_LIBFLAGS construction
variable which is constructed by respectively prepending and
appending the values of the $LIBLINKPREFIX and $LIBLINKSUFFIX
construction variables to each library name.

Any command lines you define yourself that need the libraries
from $LIBS should include $_LIBFLAGS (as well as $_LIBDIRFLAGS)
rather than $LIBS. For example:

env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBSUFFIX
The suffix used for (static) library file names. A default value
is set for each platform (posix, win32, os2, etc.), but the value
is overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
etc.) to reflect the names of the libraries they create.

LIBSUFFIXES
A list of all legal suffixes for library file names. on the
current platform. When searching for library dependencies, SCons
will look for files with prefixes from the $LIBPREFIXES list, the
base library name, and these suffixes.

LICENSE
The abbreviated name, preferably the SPDX code, of the license
under which this project is released (GPL-3.0, LGPL-2.1,
BSD-2-Clause etc.). See
http://www.opensource.org/licenses/alphabetical[8] for a list of
license names and SPDX codes.

See the Package builder.

LINESEPARATOR
The separator used by the Substfile and Textfile builders. This
value is used between sources when constructing the target. It
defaults to the current system line separator.

LINGUAS_FILE
The $LINGUAS_FILE defines file(s) containing list of additional
linguas to be processed by POInit, POUpdate or MOFiles builders.
It also affects Translate builder. If the variable contains a
string, it defines the name of the list file. The $LINGUAS_FILE
may be a list of file names as well. If $LINGUAS_FILE is set to a
non-string truthy value, the list will be read from the file
named LINGUAS.

LINK
The linker. See also $SHLINK for linking shared objects.

On POSIX systems (those using the link tool), you should normally
not change this value as it defaults to a "smart" linker tool
which selects a compiler driver matching the type of source files
in use. So for example, if you set $CXX to a specific compiler
name, and are compiling C++ sources, the smartlink function will
automatically select the same compiler for linking.

LINKCOM
The command line used to link object files into an executable.
See also $SHLINKCOM for linking shared objects.

LINKCOMSTR
If set, the string displayed when object files are linked into an
executable. If not set, then $LINKCOM (the command line) is
displayed. See also $SHLINKCOMSTR. for linking shared objects.

env = Environment(LINKCOMSTR = "Linking $TARGET")

LINKFLAGS
General user options passed to the linker. Note that this
variable should not contain -l (or similar) options for linking
with the libraries listed in $LIBS, nor -L (or similar) library
search path options that scons generates automatically from
$LIBPATH. See $_LIBFLAGS above, for the variable that expands to
library-link options, and $_LIBDIRFLAGS above, for the variable
that expands to library search path options. See also
$SHLINKFLAGS. for linking shared objects.

M4
The M4 macro preprocessor.

M4COM
The command line used to pass files through the M4 macro
preprocessor.

M4COMSTR
The string displayed when a file is passed through the M4 macro
preprocessor. If this is not set, then $M4COM (the command line)
is displayed.

M4FLAGS
General options passed to the M4 macro preprocessor.

MAKEINDEX
The makeindex generator for the TeX formatter and typesetter and
the LaTeX structured formatter and typesetter.

MAKEINDEXCOM
The command line used to call the makeindex generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

MAKEINDEXCOMSTR
The string displayed when calling the makeindex generator for the
TeX formatter and typesetter and the LaTeX structured formatter
and typesetter. If this is not set, then $MAKEINDEXCOM (the
command line) is displayed.

MAKEINDEXFLAGS
General options passed to the makeindex generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

MAXLINELENGTH
The maximum number of characters allowed on an external command
line. On Win32 systems, link lines longer than this many
characters are linked via a temporary file name.

MIDL
The Microsoft IDL compiler.

MIDLCOM
The command line used to pass files to the Microsoft IDL
compiler.

MIDLCOMSTR
The string displayed when the Microsoft IDL compiler is called.
If this is not set, then $MIDLCOM (the command line) is
displayed.

MIDLFLAGS
General options passed to the Microsoft IDL compiler.

MOSUFFIX
Suffix used for MO files (default: '.mo'). See msgfmt tool and
MOFiles builder.

MSGFMT
Absolute path to msgfmt(1) binary, found by Detect(). See msgfmt
tool and MOFiles builder.

MSGFMTCOM
Complete command line to run msgfmt(1) program. See msgfmt tool
and MOFiles builder.

MSGFMTCOMSTR
String to display when msgfmt(1) is invoked (default: '', which
means ``print $MSGFMTCOM''). See msgfmt tool and MOFiles builder.

MSGFMTFLAGS
Additional flags to msgfmt(1). See msgfmt tool and MOFiles
builder.

MSGINIT
Path to msginit(1) program (found via Detect). See msginit tool
and POInit builder.

MSGINITCOM
Complete command line to run msginit(1) program. See msginit tool
and POInit builder.

MSGINITCOMSTR
String to display when msginit(1) is invoked. The default is an
empty string, which will print the command line ($MSGINITCOM).
See msginit tool and POInit builder.

MSGINITFLAGS
List of additional flags to msginit(1) (default: []). See msginit
tool and POInit builder.

_MSGINITLOCALE
Internal ``macro''. Computes locale (language) name based on
target filename (default: '${TARGET.filebase}').

See msginit tool and POInit builder.

MSGMERGE
Absolute path to msgmerge(1) binary as found by Detect(). See
msgmerge tool and POUpdate builder.

MSGMERGECOM
Complete command line to run msgmerge(1) command. See msgmerge
tool and POUpdate builder.

MSGMERGECOMSTR
String to be displayed when msgmerge(1) is invoked. The default
is an empty string, which will print the command line
($MSGMERGECOM). See msgmerge tool and POUpdate builder.

MSGMERGEFLAGS
Additional flags to msgmerge(1) command. See msgmerge tool and
POUpdate builder.

MSSDK_DIR
The directory containing the Microsoft SDK (either Platform SDK
or Windows SDK) to be used for compilation.

MSSDK_VERSION
The version string of the Microsoft SDK (either Platform SDK or
Windows SDK) to be used for compilation. Supported versions
include 6.1, 6.0A, 6.0, 2003R2 and 2003R1.

MSVC_BATCH
When set to any true value, specifies that SCons should batch
compilation of object files when calling the Microsoft Visual C++
compiler. All compilations of source files from the same source
directory that generate target files in a same output directory
and were configured in SCons using the same construction
environment will be built in a single call to the compiler. Only
source files that have changed since their object files were
built will be passed to each compiler invocation (via the
$CHANGED_SOURCES construction variable). Any compilations where
the object (target) file base name (minus the .obj) does not
match the source file base name will be compiled separately.

MSVC_NOTFOUND_POLICY
Specify the scons behavior when the Microsoft Visual C++ compiler
is not detected.

The $MSVC_NOTFOUND_POLICY specifies the scons behavior when no
msvc versions are detected or when the requested msvc version is
not detected.

The valid values for $MSVC_NOTFOUND_POLICY and the corresponding
scons behavior are:

'Error' or 'Exception'
Raise an exception when no msvc versions are detected or when
the requested msvc version is not detected.

'Warning' or 'Warn'
Issue a warning and continue when no msvc versions are
detected or when the requested msvc version is not detected.
Depending on usage, this could result in build failure(s).

'Ignore' or 'Suppress'
Take no action and continue when no msvc versions are
detected or when the requested msvc version is not detected.
Depending on usage, this could result in build failure(s).

Note: in addition to the camel case values shown above, lower
case and upper case values are accepted as well.

The $MSVC_NOTFOUND_POLICY is applied when any of the following
conditions are satisfied:

+o $MSVC_VERSION is specified, the default tools list is
implicitly defined (i.e., the tools list is not specified),
and the default tools list contains one or more of the msvc
tools.

+o $MSVC_VERSION is specified, the default tools list is
explicitly specified (e.g., tools=['default']), and the
default tools list contains one or more of the msvc tools.

+o A non-default tools list is specified that contains one or
more of the msvc tools (e.g., tools=['msvc', 'mslink']).

The $MSVC_NOTFOUND_POLICY is ignored when any of the following
conditions are satisfied:

+o $MSVC_VERSION is not specified and the default tools list is
implicitly defined (i.e., the tools list is not specified).

+o $MSVC_VERSION is not specified and the default tools list is
explicitly specified (e.g., tools=['default']).

+o A non-default tool list is specified that does not contain
any of the msvc tools (e.g., tools=['mingw']).

Important usage details:

+o $MSVC_NOTFOUND_POLICY must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_NOTFOUND_POLICY must be set before the first msvc tool
is loaded into the environment.

When $MSVC_NOTFOUND_POLICY is not specified, the default scons
behavior is to issue a warning and continue subject to the
conditions listed above. The default scons behavior may change in
the future.

New in version 4.4

MSVC_SCRIPT_ARGS
Pass user-defined arguments to the Microsoft Visual C++ batch
file determined via autodetection.


$MSVC_SCRIPT_ARGS is available for msvc batch file arguments that
do not have first-class support via construction variables or
when there is an issue with the appropriate construction variable
validation. When available, it is recommended to use the
appropriate construction variables (e.g., $MSVC_TOOLSET_VERSION)
rather than $MSVC_SCRIPT_ARGS arguments.

The valid values for $MSVC_SCRIPT_ARGS are: None, a string, or a
list of strings.

The $MSVC_SCRIPT_ARGS value is converted to a scalar string
(i.e., "flattened"). The resulting scalar string, if not empty,
is passed as an argument to the msvc batch file determined via
autodetection subject to the validation conditions listed below.


$MSVC_SCRIPT_ARGS is ignored when the value is None and when the
result from argument conversion is an empty string. The
validation conditions below do not apply.

An exception is raised when any of the following conditions are
satisfied:

+o $MSVC_SCRIPT_ARGS is specified for Visual Studio 2013 and
earlier.

+o Multiple SDK version arguments (e.g., '10.0.20348.0') are
specified in $MSVC_SCRIPT_ARGS.

+o $MSVC_SDK_VERSION is specified and an SDK version argument
(e.g., '10.0.20348.0') is specified in $MSVC_SCRIPT_ARGS.
Multiple SDK version declarations via $MSVC_SDK_VERSION and
$MSVC_SCRIPT_ARGS are not allowed.

+o Multiple toolset version arguments (e.g.,
'-vcvars_ver=14.29') are specified in $MSVC_SCRIPT_ARGS.

+o $MSVC_TOOLSET_VERSION is specified and a toolset version
argument (e.g., '-vcvars_ver=14.29') is specified in
$MSVC_SCRIPT_ARGS. Multiple toolset version declarations via
$MSVC_TOOLSET_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

+o Multiple spectre library arguments (e.g.,
'-vcvars_spectre_libs=spectre') are specified in
$MSVC_SCRIPT_ARGS.

+o $MSVC_SPECTRE_LIBS is enabled and a spectre library argument
(e.g., '-vcvars_spectre_libs=spectre') is specified in
$MSVC_SCRIPT_ARGS. Multiple spectre library declarations via
$MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are not allowed.

+o Multiple UWP arguments (e.g., uwp or store) are specified in
$MSVC_SCRIPT_ARGS.

+o $MSVC_UWP_APP is enabled and a UWP argument (e.g., uwp or
store) is specified in $MSVC_SCRIPT_ARGS. Multiple UWP
declarations via $MSVC_UWP_APP and $MSVC_SCRIPT_ARGS are not
allowed.

Example 1 - A Visual Studio 2022 build with an SDK version and a
toolset version specified with a string argument:

env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS='10.0.20348.0 -vcvars_ver=14.29.30133')

Example 2 - A Visual Studio 2022 build with an SDK version and a
toolset version specified with a list argument:

env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['10.0.20348.0', '-vcvars_ver=14.29.30133'])

Important usage details:

+o $MSVC_SCRIPT_ARGS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_SCRIPT_ARGS must be set before the first msvc tool is
loaded into the environment.

+o Other than checking for multiple declarations as described
above, $MSVC_SCRIPT_ARGS arguments are not validated.

+o Erroneous, inconsistent, and/or version incompatible
$MSVC_SCRIPT_ARGS arguments are likely to result in build
failures for reasons that are not readily apparent and may be
difficult to diagnose. The burden is on the user to ensure
that the arguments provided to the msvc batch file are valid,
consistent and compatible with the version of msvc selected.

New in version 4.4

MSVC_SCRIPTERROR_POLICY
Specify the scons behavior when Microsoft Visual C++ batch file
errors are detected.

The $MSVC_SCRIPTERROR_POLICY specifies the scons behavior when
msvc batch file errors are detected. When
$MSVC_SCRIPTERROR_POLICY is not specified, the default scons
behavior is to suppress msvc batch file error messages.

The root cause of msvc build failures may be difficult to
diagnose. In these situations, setting the scons behavior to
issue a warning when msvc batch file errors are detected may
produce additional diagnostic information.

The valid values for $MSVC_SCRIPTERROR_POLICY and the
corresponding scons behavior are:

'Error' or 'Exception'
Raise an exception when msvc batch file errors are detected.

'Warning' or 'Warn'
Issue a warning when msvc batch file errors are detected.

'Ignore' or 'Suppress'
Suppress msvc batch file error messages.

New in version 4.4

Note: in addition to the camel case values shown above, lower
case and upper case values are accepted as well.

Example 1 - A Visual Studio 2022 build with user-defined script
arguments:

env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'])
env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

Example 1 - Output fragment:

...
link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'
...

Example 2 - A Visual Studio 2022 build with user-defined script
arguments and the script error policy set to issue a warning when
msvc batch file errors are detected:

env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'], MSVC_SCRIPTERROR_POLICY='warn')
env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

Example 2 - Output fragment:

...
scons: warning: vc script errors detected:
[ERROR:vcvars.bat] The UWP Application Platform requires a Windows 10 SDK.
[ERROR:vcvars.bat] WindowsSdkDir = "C:\Program Files (x86)\Windows Kits\8.1\"
[ERROR:vcvars.bat] host/target architecture is not supported : { x64 , x64 }
...
link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'

Important usage details:

+o $MSVC_SCRIPTERROR_POLICY must be passed as an argument to
the Environment constructor when an msvc tool (e.g., msvc,
msvs, etc.) is loaded via the default tools list or via a
tools list passed to the Environment constructor. Otherwise,
$MSVC_SCRIPTERROR_POLICY must be set before the first msvc
tool is loaded into the environment.

+o Due to scons implementation details, not all Windows system
environment variables are propagated to the environment in
which the msvc batch file is executed. Depending on Visual
Studio version and installation options, non-fatal msvc batch
file error messages may be generated for ancillary tools
which may not affect builds with the msvc compiler. For this
reason, caution is recommended when setting the script error
policy to raise an exception (e.g., 'Error').

New in version 4.4

MSVC_SDK_VERSION
Build with a specific version of the Microsoft Software
Development Kit (SDK).

The valid values for $MSVC_SDK_VERSION are: None or a string
containing the requested SDK version (e.g., '10.0.20348.0').


$MSVC_SDK_VERSION is ignored when the value is None and when the
value is an empty string. The validation conditions below do not
apply.

An exception is raised when any of the following conditions are
satisfied:

+o $MSVC_SDK_VERSION is specified for Visual Studio 2013 and
earlier.

+o $MSVC_SDK_VERSION is specified and an SDK version argument
is specified in $MSVC_SCRIPT_ARGS. Multiple SDK version
declarations via $MSVC_SDK_VERSION and $MSVC_SCRIPT_ARGS are
not allowed.

+o The $MSVC_SDK_VERSION specified does not match any of the
supported formats:

+o '10.0.XXXXX.Y' [SDK 10.0]

+o '8.1' [SDK 8.1]


+o The system folder for the corresponding $MSVC_SDK_VERSION
version is not found. The requested SDK version does not
appear to be installed.

+o The $MSVC_SDK_VERSION version does not appear to support the
requested platform type (i.e., UWP or Desktop). The requested
SDK version platform type components do not appear to be
installed.

+o The $MSVC_SDK_VERSION version is 8.1, the platform type is
UWP, and the build tools selected are from Visual Studio 2017
and later (i.e., $MSVC_VERSION must be '14.0' or
$MSVC_TOOLSET_VERSION must be '14.0').

Example 1 - A Visual Studio 2022 build with a specific Windows
SDK version:

env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0')

Example 2 - A Visual Studio 2022 build with a specific SDK
version for the Universal Windows Platform:

env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0', MSVC_UWP_APP=True)

Important usage details:

+o $MSVC_SDK_VERSION must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_SDK_VERSION must be set before the first msvc tool is
loaded into the environment.

+o Should a SDK 10.0 version be installed that does not follow
the naming scheme above, the SDK version will need to be
specified via $MSVC_SCRIPT_ARGS until the version number
validation format can be extended.

+o Should an exception be raised indicating that the SDK version
is not found, verify that the requested SDK version is
installed with the necessary platform type components.

+o There is a known issue with the Microsoft libraries when the
target architecture is ARM64 and a Windows 11 SDK (version
'10.0.22000.0' and later) is used with the v141 build tools
and older v142 toolsets (versions '14.28.29333' and earlier).
Should build failures arise with these combinations of
settings due to unresolved symbols in the Microsoft
libraries, $MSVC_SDK_VERSION may be employed to specify a
Windows 10 SDK (e.g., '10.0.20348.0') for the build.

New in version 4.4

MSVC_SPECTRE_LIBS
Build with the spectre-mitigated Microsoft Visual C++ libraries.

The valid values for $MSVC_SPECTRE_LIBS are: True, False, or
None.

When $MSVC_SPECTRE_LIBS is enabled (i.e., True), the Microsoft
Visual C++ environment will include the paths to the
spectre-mitigated implementations of the Microsoft Visual C++
libraries.

An exception is raised when any of the following conditions are
satisfied:

+o $MSVC_SPECTRE_LIBS is enabled for Visual Studio 2015 and
earlier.

+o $MSVC_SPECTRE_LIBS is enabled and a spectre library argument
is specified in $MSVC_SCRIPT_ARGS. Multiple spectre library
declarations via $MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are
not allowed.

+o $MSVC_SPECTRE_LIBS is enabled and the platform type is UWP.
There are no spectre-mitigated libraries for Universal
Windows Platform (UWP) applications or components.

Example - A Visual Studio 2022 build with spectre mitigated
Microsoft Visual C++ libraries:

env = Environment(MSVC_VERSION='14.3', MSVC_SPECTRE_LIBS=True)

Important usage details:

+o $MSVC_SPECTRE_LIBS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_SPECTRE_LIBS must be set before the first msvc tool is
loaded into the environment.

+o Additional compiler switches (e.g., /Qspectre) are necessary
for including spectre mitigations when building user
artifacts. Refer to the Visual Studio documentation for
details.

+o The existence of the spectre libraries host architecture
and target architecture folders are not verified when
$MSVC_SPECTRE_LIBS is enabled which could result in build
failures. The burden is on the user to ensure the requisite
libraries with spectre mitigations are installed.

New in version 4.4

MSVC_TOOLSET_VERSION
Build with a specific Microsoft Visual C++ toolset version.

Specifying $MSVC_TOOLSET_VERSION does not affect the
autodetection and selection of msvc instances. The
$MSVC_TOOLSET_VERSION is applied after an msvc instance is
selected. This could be the default version of msvc if
$MSVC_VERSION is not specified.

The valid values for $MSVC_TOOLSET_VERSION are: None or a string
containing the requested toolset version (e.g., '14.29').


$MSVC_TOOLSET_VERSION is ignored when the value is None and when
the value is an empty string. The validation conditions below do
not apply.

An exception is raised when any of the following conditions are
satisfied:

+o $MSVC_TOOLSET_VERSION is specified for Visual Studio 2015
and earlier.

+o $MSVC_TOOLSET_VERSION is specified and a toolset version
argument is specified in $MSVC_SCRIPT_ARGS. Multiple toolset
version declarations via $MSVC_TOOLSET_VERSION and
$MSVC_SCRIPT_ARGS are not allowed.

+o The $MSVC_TOOLSET_VERSION specified does not match any of the
supported formats:

+o 'XX.Y'

+o 'XX.YY'

+o 'XX.YY.ZZZZZ'

+o 'XX.YY.Z' to 'XX.YY.ZZZZ' [scons extension not directly
supported by the msvc batch files and may be removed in
the future]

+o 'XX.YY.ZZ.N' [SxS format]

+o 'XX.YY.ZZ.NN' [SxS format]

+o The major msvc version prefix (i.e., 'XX.Y') of the
$MSVC_TOOLSET_VERSION specified is for Visual Studio 2013 and
earlier (e.g., '12.0').

+o The major msvc version prefix (i.e., 'XX.Y') of the
$MSVC_TOOLSET_VERSION specified is greater than the msvc
version selected (e.g., '99.0').

+o A system folder for the corresponding $MSVC_TOOLSET_VERSION
version is not found. The requested toolset version does not
appear to be installed.

Toolset selection details:

+o When $MSVC_TOOLSET_VERSION is not an SxS version number or a
full toolset version number: the first toolset version,
ranked in descending order, that matches the
$MSVC_TOOLSET_VERSION prefix is selected.

+o When $MSVC_TOOLSET_VERSION is specified using the major msvc
version prefix (i.e., 'XX.Y') and the major msvc version is
that of the latest release of Visual Studio, the selected
toolset version may not be the same as the default Microsoft
Visual C++ toolset version.

In the latest release of Visual Studio, the default Microsoft
Visual C++ toolset version is not necessarily the toolset
with the largest version number.

Example 1 - A default Visual Studio build with a partial toolset
version specified:

env = Environment(MSVC_TOOLSET_VERSION='14.2')

Example 2 - A default Visual Studio build with a partial toolset
version specified:

env = Environment(MSVC_TOOLSET_VERSION='14.29')

Example 3 - A Visual Studio 2022 build with a full toolset
version specified:

env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.30133')

Example 4 - A Visual Studio 2022 build with an SxS toolset
version specified:

env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.16.11')

Important usage details:

+o $MSVC_TOOLSET_VERSION must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_TOOLSET_VERSION must be set before the first msvc tool
is loaded into the environment.

+o The existence of the toolset host architecture and target
architecture folders are not verified when
$MSVC_TOOLSET_VERSION is specified which could result in
build failures. The burden is on the user to ensure the
requisite toolset target architecture build tools are
installed.

New in version 4.4

MSVC_USE_SCRIPT
Use a batch script to set up the Microsoft Visual C++ compiler.

If set to the name of a Visual Studio .bat file (e.g.
vcvars.bat), SCons will run that batch file instead of the
auto-detected one, and extract the relevant variables from the
result (typically %INCLUDE%, %LIB%, and %PATH%) for supplying to
the build. This can be useful to force the use of a compiler
version that SCons does not detect. $MSVC_USE_SCRIPT_ARGS
provides arguments passed to this script.

Setting $MSVC_USE_SCRIPT to None bypasses the Visual Studio
autodetection entirely; use this if you are running SCons in a
Visual Studio cmd window and importing the shell's environment
variables - that is, if you are sure everything is set correctly
already and you don't want SCons to change anything.


$MSVC_USE_SCRIPT ignores $MSVC_VERSION and $TARGET_ARCH.

Changed in version 4.4: new $MSVC_USE_SCRIPT_ARGS provides a way
to pass arguments.

MSVC_USE_SCRIPT_ARGS
Provides arguments passed to the script $MSVC_USE_SCRIPT.

New in version 4.4

MSVC_USE_SETTINGS
Use a dictionary to set up the Microsoft Visual C++ compiler.


$MSVC_USE_SETTINGS is ignored when $MSVC_USE_SCRIPT is defined
and/or when $MSVC_USE_SETTINGS is set to None.

The dictionary is used to populate the environment with the
relevant variables (typically %INCLUDE%, %LIB%, and %PATH%) for
supplying to the build. This can be useful to force the use of a
compiler environment that SCons does not configure correctly.
This is an alternative to manually configuring the environment
when bypassing Visual Studio autodetection entirely by setting
$MSVC_USE_SCRIPT to None.

Here is an example of configuring a build environment using the
Microsoft Visual C++ compiler included in the Microsoft SDK on a
64-bit host and building for a 64-bit architecture:

# Microsoft SDK 6.0 (MSVC 8.0): 64-bit host and 64-bit target
msvc_use_settings = {
"PATH": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Bin\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin",
"C:\\Windows\\Microsoft.NET\\Framework\\v2.0.50727",
"C:\\Windows\\system32",
"C:\\Windows",
"C:\\Windows\\System32\\Wbem",
"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\"
],
"INCLUDE": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include\\Sys",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include\\gl",
],
"LIB": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Lib\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Lib\\x64",
],
"LIBPATH": [],
"VSCMD_ARG_app_plat": [],
"VCINSTALLDIR": [],
"VCToolsInstallDir": []
}

# Specifying MSVC_VERSION is recommended
env = Environment(MSVC_VERSION='8.0', MSVC_USE_SETTINGS=msvc_use_settings)

Important usage details:

+o $MSVC_USE_SETTINGS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_USE_SETTINGS must be set before the first msvc tool is
loaded into the environment.

+o The dictionary content requirements are based on the
internal msvc implementation and therefore may change at any
time. The burden is on the user to ensure the dictionary
contents are minimally sufficient to ensure successful
builds.

New in version 4.4

MSVC_UWP_APP
Build with the Universal Windows Platform (UWP) application
Microsoft Visual C++ libraries.

The valid values for $MSVC_UWP_APP are: True, '1', False, '0', or
None.

When $MSVC_UWP_APP is enabled (i.e., True or '1'), the Microsoft
Visual C++ environment will be set up to point to the Windows
Store compatible libraries and Microsoft Visual C++ runtimes. In
doing so, any libraries that are built will be able to be used in
a UWP App and published to the Windows Store.


An exception is raised when any of the following conditions are
satisfied:

+o $MSVC_UWP_APP is enabled for Visual Studio 2013 and earlier.

+o $MSVC_UWP_APP is enabled and a UWP argument is specified in
$MSVC_SCRIPT_ARGS. Multiple UWP declarations via
$MSVC_UWP_APP and $MSVC_SCRIPT_ARGS are not allowed.

Example - A Visual Studio 2022 build for the Universal Windows
Platform:

env = Environment(MSVC_VERSION='14.3', MSVC_UWP_APP=True)

Important usage details:

+o $MSVC_UWP_APP must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools
list passed to the Environment constructor. Otherwise,
$MSVC_UWP_APP must be set before the first msvc tool is
loaded into the environment.

+o The existence of the UWP libraries is not verified when
$MSVC_UWP_APP is enabled which could result in build
failures. The burden is on the user to ensure the requisite
UWP libraries are installed.


MSVC_VERSION
A string to select the preferred version of Microsoft Visual C++.
If the specified version is unavailable and/or unknown to SCons,
a warning is issued showing the versions actually discovered, and
the build will eventually fail indicating a missing compiler
binary. If $MSVC_VERSION is not set, SCons will (by default)
select the latest version of Microsoft Visual C++ installed on
your system (excluding any preview versions).

Note
In order to take effect, $MSVC_VERSION must be set before the
initial Microsoft Visual C++ compiler discovery takes place.
Discovery happens, at the latest, during the first call to
the Environment function, unless a tools list is specified
which excludes the entire Microsoft Visual C++ toolchain -
that is, omits "defaults" and any specific tool module that
refers to parts of the toolchain (msvc, mslink, masm, midl
and msvs). In this case, detection is deferred until any one
of those tool modules is invoked manually. The following two
examples illustrate this:

# MSVC_VERSION set as Environment is created
env = Environment(MSVC_VERSION='14.2')

# Initialization deferred with empty tools, triggered manually
env = Environment(tools=[])
env['MSVC_VERSION'] = '14.2
env.Tool('msvc')
env.Tool('mslink')
env.Tool('msvs')

The valid values for $MSVC_VERSION represent major versions of
the compiler, except that versions ending in Exp refer to
"Express" or "Express for Desktop" Visual Studio editions. Values
that do not look like a valid compiler version string are not
supported.

The following table shows the correspondence of $MSVC_VERSION
values to various version indicators ('x' is used as a
placeholder for a single digit that can vary).

+----------+---------------+-----------+---------------+---------------+
|SCons Key | Visual C++ | _MSVC_VER | Visual Studio | MSBuild / |
| | Version | | Product | Visual Studio |
+----------+---------------+-----------+---------------+---------------+
|"14.3" | 14.3x | 193x | Visual Studio | 17.x, 17.1x |
| | | | 2022 | |
+----------+---------------+-----------+---------------+---------------+
|"14.2" | 14.2x | 192x | Visual Studio | 16.x, 16.1x |
| | | | 2019 | |
+----------+---------------+-----------+---------------+---------------+
|"14.1" | 14.1 or 14.1x | 191x | Visual Studio | 15.x |
| | | | 2017 | |
+----------+---------------+-----------+---------------+---------------+
|"14.1Exp" | 14.1 or 14.1x | 191x | Visual Studio | 15.x |
| | | | 2017 Express | |
+----------+---------------+-----------+---------------+---------------+
|"14.0" | 14.0 | 1900 | Visual Studio | 14.0 |
| | | | 2015 | |
+----------+---------------+-----------+---------------+---------------+
|"14.0Exp" | 14.0 | 1900 | Visual Studio | 14.0 |
| | | | 2015 Express | |
+----------+---------------+-----------+---------------+---------------+
|"12.0" | 12.0 | 1800 | Visual Studio | 12.0 |
| | | | 2013 | |
+----------+---------------+-----------+---------------+---------------+
|"12.0Exp" | 12.0 | 1800 | Visual Studio | 12.0 |
| | | | 2013 Express | |
+----------+---------------+-----------+---------------+---------------+
|"11.0" | 11.0 | 1700 | Visual Studio | 11.0 |
| | | | 2012 | |
+----------+---------------+-----------+---------------+---------------+
|"11.0Exp" | 11.0 | 1700 | Visual Studio | 11.0 |
| | | | 2012 Express | |
+----------+---------------+-----------+---------------+---------------+
|"10.0" | 10.0 | 1600 | Visual Studio | 10.0 |
| | | | 2010 | |
+----------+---------------+-----------+---------------+---------------+
|"10.0Exp" | 10.0 | 1600 | Visual C++ | 10.0 |
| | | | Express 2010 | |
+----------+---------------+-----------+---------------+---------------+
|"9.0" | 9.0 | 1500 | Visual Studio | 9.0 |
| | | | 2008 | |
+----------+---------------+-----------+---------------+---------------+
|"9.0Exp" | 9.0 | 1500 | Visual C++ | 9.0 |
| | | | Express 2008 | |
+----------+---------------+-----------+---------------+---------------+
|"8.0" | 8.0 | 1400 | Visual Studio | 8.0 |
| | | | 2005 | |
+----------+---------------+-----------+---------------+---------------+
|"8.0Exp" | 8.0 | 1400 | Visual C++ | 8.0 |
| | | | Express 2005 | |
+----------+---------------+-----------+---------------+---------------+
|"7.1" | 7.1 | 1300 | Visual Studio | 7.1 |
| | | | .NET 2003 | |
+----------+---------------+-----------+---------------+---------------+
|"7.0" | 7.0 | 1200 | Visual Studio | 7.0 |
| | | | .NET 2002 | |
+----------+---------------+-----------+---------------+---------------+
|"6.0" | 6.0 | 1100 | Visual Studio | 6.0 |
| | | | 6.0 | |
+----------+---------------+-----------+---------------+---------------+

Note

+o It is not necessary to install a Visual Studio IDE to
build with SCons (for example, you can install only Build
Tools), but when a Visual Studio IDE is installed,
additional builders such as MSVSSolution and MSVSProject
become available and correspond to the specified
versions.

+o Versions ending in Exp refer to historical "Express" or
"Express for Desktop" Visual Studio editions, which had
feature limitations compared to the full editions. It is
only necessary to specify the Exp suffix to select the
express edition when both express and non-express
editions of the same product are installed
simultaneously. The Exp suffix is unnecessary, but
accepted, when only the express edition is installed.
The compilation environment can be further or more precisely
specified through the use of several other construction
variables: see the descriptions of $MSVC_TOOLSET_VERSION,
$MSVC_SDK_VERSION, $MSVC_USE_SCRIPT, $MSVC_USE_SCRIPT_ARGS, and
$MSVC_USE_SETTINGS.

MSVS
When the Microsoft Visual Studio tools are initialized, they set
up this dictionary with the following keys:

VERSION
the version of MSVS being used (can be set via $MSVC_VERSION)

VERSIONS
the available versions of MSVS installed

VCINSTALLDIR
installed directory of Microsoft Visual C++

VSINSTALLDIR
installed directory of Visual Studio

FRAMEWORKDIR
installed directory of the .NET framework

FRAMEWORKVERSIONS
list of installed versions of the .NET framework, sorted
latest to oldest.

FRAMEWORKVERSION
latest installed version of the .NET framework

FRAMEWORKSDKDIR
installed location of the .NET SDK.

PLATFORMSDKDIR
installed location of the Platform SDK.

PLATFORMSDK_MODULES
dictionary of installed Platform SDK modules, where the
dictionary keys are keywords for the various modules, and the
values are 2-tuples where the first is the release date, and
the second is the version number.

If a value is not set, it was not available in the registry.
Visual Studio 2017 and later do not use the registry for primary
storage of this information, so typically for these versions only
PROJECTSUFFIX and SOLUTIONSUFFIX will be set.

MSVS_ARCH
Sets the architecture for which the generated project(s) should
build.

The default value is x86. amd64 is also supported by SCons for
most Visual Studio versions. Since Visual Studio 2015 arm is
supported, and since Visual Studio 2017 arm64 is supported.
Trying to set $MSVS_ARCH to an architecture that's not supported
for a given Visual Studio version will generate an error.

MSVS_PROJECT_GUID
The string placed in a generated Microsoft Visual C++ project
file as the value of the ProjectGUID attribute. There is no
default value. If not defined, a new GUID is generated.

MSVS_SCC_AUX_PATH
The path name placed in a generated Microsoft Visual C++ project
file as the value of the SccAuxPath attribute if the
MSVS_SCC_PROVIDER construction variable is also set. There is no
default value.

MSVS_SCC_CONNECTION_ROOT
The root path of projects in your SCC workspace, i.e the path
under which all project and solution files will be generated. It
is used as a reference path from which the relative paths of the
generated Microsoft Visual C++ project and solution files are
computed. The relative project file path is placed as the value
of the SccLocalPath attribute of the project file and as the
values of the SccProjectFilePathRelativizedFromConnection[i]
(where [i] ranges from 0 to the number of projects in the
solution) attributes of the GlobalSection(SourceCodeControl)
section of the Microsoft Visual Studio solution file. Similarly,
the relative solution file path is placed as the values of the
SccLocalPath[i] (where [i] ranges from 0 to the number of
projects in the solution) attributes of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. This is used only if the MSVS_SCC_PROVIDER
construction variable is also set. The default value is the
current working directory.

MSVS_SCC_PROJECT_NAME
The project name placed in a generated Microsoft Visual C++
project file as the value of the SccProjectName attribute if the
MSVS_SCC_PROVIDER construction variable is also set. In this case
the string is also placed in the SccProjectName0 attribute of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. There is no default value.

MSVS_SCC_PROVIDER
The string placed in a generated Microsoft Visual C++ project
file as the value of the SccProvider attribute. The string is
also placed in the SccProvider0 attribute of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. There is no default value.

MSVS_VERSION
Set the preferred version of Microsoft Visual Studio to use.

If $MSVS_VERSION is not set, SCons will (by default) select the
latest version of Visual Studio installed on your system. So, if
you have version 6 and version 7 (MSVS .NET) installed, it will
prefer version 7. You can override this by specifying the
$MSVS_VERSION variable when initializing the Environment, setting
it to the appropriate version ('6.0' or '7.0', for example). If
the specified version isn't installed, tool initialization will
fail.


Deprecated since 1.3.0: $MSVS_VERSION is deprecated in favor of
$MSVC_VERSION. As a transitional aid, if $MSVS_VERSION is set and
$MSVC_VERSION is not, $MSVC_VERSION will be initialized to the
value of $MSVS_VERSION. An error is raised if both are set and
have different values.

MSVSBUILDCOM
The build command line placed in a generated Microsoft Visual C++
project file. The default is to have Visual Studio invoke SCons
with any specified build targets.

MSVSCLEANCOM
The clean command line placed in a generated Microsoft Visual C++
project file. The default is to have Visual Studio invoke SCons
with the -c option to remove any specified targets.

MSVSENCODING
The encoding string placed in a generated Microsoft Visual C++
project file. The default is encoding Windows-1252.

MSVSPROJECTCOM
The action used to generate Microsoft Visual C++ project files.

MSVSPROJECTSUFFIX
The suffix used for Microsoft Visual C++ project (DSP) files. The
default value is .vcxproj when using Visual Studio 2010 and
later, .vcproj when using Visual Studio versions between 2002 and
2008, and .dsp when using Visual Studio 6.0.

MSVSREBUILDCOM
The rebuild command line placed in a generated Microsoft Visual
C++ project file. The default is to have Visual Studio invoke
SCons with any specified rebuild targets.

MSVSSCONS
The SCons used in generated Microsoft Visual C++ project files.
The default is the version of SCons being used to generate the
project file.

MSVSSCONSCOM
The default SCons command used in generated Microsoft Visual C++
project files.

MSVSSCONSCRIPT
The sconscript file (that is, SConstruct or SConscript file) that
will be invoked by Microsoft Visual C++ project files (through
the $MSVSSCONSCOM variable). The default is the same sconscript
file that contains the call to MSVSProject to build the project
file.

MSVSSCONSFLAGS
The SCons flags used in generated Microsoft Visual C++ project
files.

MSVSSOLUTIONCOM
The action used to generate Microsoft Visual Studio solution
files.

MSVSSOLUTIONSUFFIX
The suffix used for Microsoft Visual Studio solution (DSW) files.
The default value is .sln when using Visual Studio version 7.x
(.NET 2002) and later, and .dsw when using Visual Studio 6.0.

MT
The program used on Windows systems to embed manifests into DLLs
and EXEs. See also $WINDOWS_EMBED_MANIFEST.

MTEXECOM
The Windows command line used to embed manifests into
executables. See also $MTSHLIBCOM.

MTFLAGS
Flags passed to the $MT manifest embedding program (Windows
only).

MTSHLIBCOM
The Windows command line used to embed manifests into shared
libraries (DLLs). See also $MTEXECOM.

MWCW_VERSION
The version number of the MetroWerks CodeWarrior C compiler to be
used.

MWCW_VERSIONS
A list of installed versions of the MetroWerks CodeWarrior C
compiler on this system.

NAME
Specfies the name of the project to package.

See the Package builder.

NINJA_ALIAS_NAME
The name of the alias target which will cause SCons to create the
ninja build file, and then (optionally) run ninja. The default
value is generate-ninja.

NINJA_CMD_ARGS
A string which will pass arguments through SCons to the ninja
command when scons executes ninja. Has no effect if
$NINJA_DISABLE_AUTO_RUN is set.

This value can also be passed on the command line:

scons NINJA_CMD_ARGS=-v
or
scons NINJA_CMD_ARGS="-v -j 3"


NINJA_COMPDB_EXPAND
Boolean value to instruct ninja to expand the command line
arguments normally put into response files. If true, prevents
unexpanded lines in the compilation database like "gcc @rsp_file"
and instead yields expanded lines like "gcc -c -o myfile.o
myfile.c -Ia -DXYZ".

Ninja's compdb tool added the -x flag in Ninja V1.9.0

NINJA_DEPFILE_PARSE_FORMAT
Determines the type of format ninja should expect when parsing
header include depfiles. Can be msvc, gcc, or clang. The msvc
option corresponds to /showIncludes format, and gcc or clang
correspond to -MMD -MF.

NINJA_DIR
The builddir value. Propagates directly into the generated ninja
build file. From Ninja's docs: " A directory for some Ninja
output files. ... (You can also store other build output in this
directory.) " The default value is .ninja.

NINJA_DISABLE_AUTO_RUN
Boolean. Default: False. If true, SCons will not run ninja
automatically after creating the ninja build file.

If not explicitly set, this will be set to True if
--disable_execute_ninja or SetOption('disable_execute_ninja',
True) is seen.

NINJA_ENV_VAR_CACHE
A string that sets the environment for any environment variables
that differ between the OS environment and the SCons execution
environment.

It will be compatible with the default shell of the operating
system.

If not explicitly set, SCons will generate this dynamically from
the execution environment stored in the current construction
environment (e.g. env['ENV']) where those values differ from the
existing shell..

NINJA_FILE_NAME
The filename for the generated Ninja build file. The default is
ninja.build.

NINJA_FORCE_SCONS_BUILD
If true, causes the build nodes to call back to scons instead of
using ninja to build them. This is intended to be passed to the
environment on the builder invocation. It is useful if you have a
build node which does something which is not easily translated
into ninja.

NINJA_GENERATED_SOURCE_ALIAS_NAME
A string matching the name of a user defined alias which
represents a list of all generated sources. This will prevent the
auto-detection of generated sources from
$NINJA_GENERATED_SOURCE_SUFFIXES. Then all other source files
will be made to depend on this in the ninja build file, forcing
the generated sources to be built first.

NINJA_GENERATED_SOURCE_SUFFIXES
The list of source file suffixes which are generated by SCons
build steps. All source files which match these suffixes will be
added to the _generated_sources alias in the output ninja build
file. Then all other source files will be made to depend on this
in the ninja build file, forcing the generated sources to be
built first.

NINJA_MSVC_DEPS_PREFIX
The msvc_deps_prefix string. Propagates directly into the
generated ninja build file. From Ninja's docs: "defines the
string which should be stripped from msvc's /showIncludes output"

NINJA_POOL
Set the ninja_pool for this or all targets in scope for this env
var.

NINJA_REGENERATE_DEPS
A generator function used to create a ninja depfile which
includes all the files which would require SCons to be invoked if
they change. Or a list of said files.

_NINJA_REGENERATE_DEPS_FUNC
Internal value used to specify the function to call with argument
env to generate the list of files which, if changed, would
require the ninja build file to be regenerated.

NINJA_SCONS_DAEMON_KEEP_ALIVE
The number of seconds for the SCons daemon launched by ninja to
stay alive. (Default: 180000)

NINJA_SCONS_DAEMON_PORT
The TCP/IP port for the SCons daemon to listen on. NOTE: You
cannot use a port already being listened to on your build
machine. (Default: random number between 10000,60000)

NINJA_SYNTAX
The path to a custom ninja_syntax.py file which is used in
generation. The tool currently assumes you have ninja installed
as a Python module and grabs the syntax file from that
installation if $NINJA_SYNTAX is not explicitly set.

no_import_lib
When set to non-zero, suppresses creation of a corresponding
Windows static import lib by the SharedLibrary builder when used
with MinGW, Microsoft Visual Studio or Metrowerks. This also
suppresses creation of an export (.exp) file when using Microsoft
Visual Studio.

OBJPREFIX
The prefix used for (static) object file names.

OBJSUFFIX
The suffix used for (static) object file names.

PACKAGEROOT
Specifies the directory where all files in resulting archive will
be placed if applicable. The default value is "$NAME-$VERSION".

See the Package builder.

PACKAGETYPE
Selects the package type to build when using the Package builder.
It may be a string or list of strings. See the documentation for
the builder for the currently supported types.


$PACKAGETYPE may be overridden with the --package-type command
line option.

See the Package builder.

PACKAGEVERSION
The version of the package (not the underlying project). This is
currently only used by the rpm packager and should reflect
changes in the packaging, not the underlying project code itself.

See the Package builder.

PCH
A node for the Microsoft Visual C++ precompiled header that will
be used when compiling object files. This variable is ignored by
tools other than Microsoft Visual C++. When this variable is
defined, SCons will add options to the compiler command line to
cause it to use the precompiled header, and will also set up the
dependencies for the PCH file. Examples:

env['PCH'] = File('StdAfx.pch')
env['PCH'] = env.PCH('pch.cc')[0]

PCHCOM
The command line used by the PCH builder to generated a
precompiled header.

PCHCOMSTR
The string displayed when generating a precompiled header. If not
set, then $PCHCOM (the command line) is displayed.

PCHPDBFLAGS
A construction variable that, when expanded, adds the /yD flag to
the command line only if the $PDB construction variable is set.

PCHSTOP
This variable specifies how much of a source file is precompiled.
This variable is ignored by tools other than Microsoft Visual
C++, or when the PCH variable is not being used. When this
variable is defined, it must be a string that is the name of the
header that is included at the end of the precompiled portion of
the source files, or the empty string if the "#pragma hrdstop"
construct is being used:

env['PCHSTOP'] = 'StdAfx.h'

PDB
The Microsoft Visual C++ PDB file that will store debugging
information for object files, shared libraries, and programs.
This variable is ignored by tools other than Microsoft Visual
C++. When this variable is defined SCons will add options to the
compiler and linker command line to cause them to generate
external debugging information, and will also set up the
dependencies for the PDB file. Example:

env['PDB'] = 'hello.pdb'

The Microsoft Visual C++ compiler switch that SCons uses by
default to generate PDB information is /Z7. This works correctly
with parallel (-j) builds because it embeds the debug information
in the intermediate object files, as opposed to sharing a single
PDB file between multiple object files. This is also the only way
to get debug information embedded into a static library. Using
the /Zi instead may yield improved link-time performance,
although parallel builds will no longer work. You can generate
PDB files with the /Zi switch by overriding the default
$CCPDBFLAGS variable; see the entry for that variable for
specific examples.

PDFLATEX
The pdflatex utility.

PDFLATEXCOM
The command line used to call the pdflatex utility.

PDFLATEXCOMSTR
The string displayed when calling the pdflatex utility. If this
is not set, then $PDFLATEXCOM (the command line) is displayed.

env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

PDFLATEXFLAGS
General options passed to the pdflatex utility.

PDFPREFIX
The prefix used for PDF file names.

PDFSUFFIX
The suffix used for PDF file names.

PDFTEX
The pdftex utility.

PDFTEXCOM
The command line used to call the pdftex utility.

PDFTEXCOMSTR
The string displayed when calling the pdftex utility. If this is
not set, then $PDFTEXCOM (the command line) is displayed.

env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

PDFTEXFLAGS
General options passed to the pdftex utility.

PKGCHK
On Solaris systems, the package-checking program that will be
used (along with $PKGINFO) to look for installed versions of the
Sun PRO C++ compiler. The default is /usr/sbin/pgkchk.

PKGINFO
On Solaris systems, the package information program that will be
used (along with $PKGCHK) to look for installed versions of the
Sun PRO C++ compiler. The default is pkginfo.

PLATFORM
The name of the platform used to create this construction
environment. SCons sets this when initializing the platform,
which by default is auto-detected (see the platform argument to
Environment).

env = Environment(tools=[])
if env['PLATFORM'] == 'cygwin':
Tool('mingw')(env)
else:
Tool('msvc')(env)


POAUTOINIT
The $POAUTOINIT variable, if set to True (on non-zero numeric
value), let the msginit tool to automatically initialize missing
PO files with msginit(1). This applies to both, POInit and
POUpdate builders (and others that use any of them).

POCREATE_ALIAS
Common alias for all PO files created with POInit builder
(default: 'po-create'). See msginit tool and POInit builder.

POSUFFIX
Suffix used for PO files (default: '.po') See msginit tool and
POInit builder.

POTDOMAIN
The $POTDOMAIN defines default domain, used to generate POT
filename as $POTDOMAIN.pot when no POT file name is provided by
the user. This applies to POTUpdate, POInit and POUpdate builders
(and builders, that use them, e.g. Translate). Normally (if
$POTDOMAIN is not defined), the builders use messages.pot as
default POT file name.

POTSUFFIX
Suffix used for PO Template files (default: '.pot'). See xgettext
tool and POTUpdate builder.

POTUPDATE_ALIAS
Name of the common phony target for all PO Templates created with
POUpdate (default: 'pot-update'). See xgettext tool and POTUpdate
builder.

POUPDATE_ALIAS
Common alias for all PO files being defined with POUpdate builder
(default: 'po-update'). See msgmerge tool and POUpdate builder.

PRINT_CMD_LINE_FUNC
A Python function used to print the command lines as they are
executed (assuming command printing is not disabled by the -q or
-s options or their equivalents). The function must accept four
arguments: s, target, source and env. s is a string showing the
command being executed, target, is the target being built (file
node, list, or string name(s)), source, is the source(s) used
(file node, list, or string name(s)), and env is the environment
being used.

The function must do the printing itself. The default
implementation, used if this variable is not set or is None, is
to just print the string, as in:

def print_cmd_line(s, target, source, env):
sys.stdout.write(s + "\n")

Here is an example of a more interesting function:

def print_cmd_line(s, target, source, env):
sys.stdout.write(
"Building %s -> %s...\n"
% (
' and '.join([str(x) for x in source]),
' and '.join([str(x) for x in target]),
)
)

env = Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
env.Program('foo', ['foo.c', 'bar.c'])

This prints:

...
scons: Building targets ...
Building bar.c -> bar.o...
Building foo.c -> foo.o...
Building foo.o and bar.o -> foo...
scons: done building targets.

Another example could be a function that logs the actual commands
to a file.

PROGEMITTER
Contains the emitter specification for the Program builder. The
manpage section "Builder Objects" contains general information on
specifying emitters.

PROGPREFIX
The prefix used for executable file names.

PROGSUFFIX
The suffix used for executable file names.

PSCOM
The command line used to convert TeX DVI files into a PostScript
file.

PSCOMSTR
The string displayed when a TeX DVI file is converted into a
PostScript file. If this is not set, then $PSCOM (the command
line) is displayed.

PSPREFIX
The prefix used for PostScript file names.

PSSUFFIX
The prefix used for PostScript file names.

QT3_AUTOSCAN
Turn off scanning for mocable files. Use the Moc Builder to
explicitly specify files to run moc on.


Changed in 4.5.0: renamed from QT_AUTOSCAN.

QT3_BINPATH
The path where the Qt binaries are installed. The default value
is '$QT3DIR/bin'.


Changed in 4.5.0: renamed from QT_BINPATH.

QT3_CPPPATH
The path where the Qt header files are installed. The default
value is '$QT3DIR/include'. Note: If you set this variable to
None, the tool won't change the $CPPPATH construction variable.


Changed in 4.5.0: renamed from QT_CPPPATH.

QT3_DEBUG
Prints lots of debugging information while scanning for moc
files.


Changed in 4.5.0: renamed from QT_DEBUG.

QT3_LIB
Default value is 'qt'. You may want to set this to 'qt-mt'. Note:
If you set this variable to None, the tool won't change the $LIBS
variable.


Changed in 4.5.0: renamed from QT_LIB.

QT3_LIBPATH
The path where the Qt libraries are installed. The default value
is '$QT3DIR/lib'. Note: If you set this variable to None, the
tool won't change the $LIBPATH construction variable.


Changed in 4.5.0: renamed from QT_LIBPATH.

QT3_MOC
Default value is '$QT3_BINPATH/moc'.

QT3_MOCCXXPREFIX
Default value is ''. Prefix for moc output files when source is a
C++ file.

QT3_MOCCXXSUFFIX
Default value is '.moc'. Suffix for moc output files when source
is a C++ file.


Changed in 4.5.0: renamed from QT_MOCCXXSUFFIX.

QT3_MOCFROMCXXCOM
Command to generate a moc file from a C++ file.


Changed in 4.5.0: renamed from QT_MOCFROMCXXCOM.

QT3_MOCFROMCXXCOMSTR
The string displayed when generating a moc file from a C++ file.
If this is not set, then $QT3_MOCFROMCXXCOM (the command line) is
displayed.


Changed in 4.5.0: renamed from QT_MOCFROMCXXCOMSTR.

QT3_MOCFROMCXXFLAGS
Default value is '-i'. These flags are passed to moc when moccing
a C++ file.


Changed in 4.5.0: renamed from QT_MOCFROMCXXFLAGS.

QT3_MOCFROMHCOM
Command to generate a moc file from a header.


Changed in 4.5.0: renamed from QT_MOCFROMSHCOM.

QT3_MOCFROMHCOMSTR
The string displayed when generating a moc file from a C++ file.
If this is not set, then $QT3_MOCFROMHCOM (the command line) is
displayed.


Changed in 4.5.0: renamed from QT_MOCFROMSHCOMSTR.

QT3_MOCFROMHFLAGS
Default value is ''. These flags are passed to moc when moccing a
header file.


Changed in 4.5.0: renamed from QT_MOCFROMSHFLAGS.

QT3_MOCHPREFIX
Default value is 'moc_'. Prefix for moc output files when source
is a header.


Changed in 4.5.0: renamed from QT_MOCHPREFIX.

QT3_MOCHSUFFIX
Default value is '$CXXFILESUFFIX'. Suffix for moc output files
when source is a header.


Changed in 4.5.0: renamed from QT_MOCHSUFFIX.

QT3_UIC
Default value is '$QT3_BINPATH/uic'.


Changed in 4.5.0: renamed from QT_UIC.

QT3_UICCOM
Command to generate header files from .ui files.


Changed in 4.5.0: renamed from QT_UICCOM.

QT3_UICCOMSTR
The string displayed when generating header files from .ui files.
If this is not set, then $QT3_UICCOM (the command line) is
displayed.


Changed in 4.5.0: renamed from QT_UICCOMSTR.

QT3_UICDECLFLAGS
Default value is ''. These flags are passed to uic when creating
a header file from a .ui file.


Changed in 4.5.0: renamed from QT_UICDECLFLAGS.

QT3_UICDECLPREFIX
Default value is ''. Prefix for uic generated header files.


Changed in 4.5.0: renamed from QT_UICDECLPREFIX.

QT3_UICDECLSUFFIX
Default value is '.h'. Suffix for uic generated header files.


Changed in 4.5.0: renamed from QT_UICDECLSUFFIX.

QT3_UICIMPLFLAGS
Default value is ''. These flags are passed to uic when creating
a C++ file from a .ui file.


Changed in 4.5.0: renamed from QT_UICIMPFLAGS.

QT3_UICIMPLPREFIX
Default value is 'uic_'. Prefix for uic generated implementation
files.


Changed in 4.5.0: renamed from QT_UICIMPLPREFIX.

QT3_UICIMPLSUFFIX
Default value is '$CXXFILESUFFIX'. Suffix for uic generated
implementation files.


Changed in 4.5.0: renamed from QT_UICIMPLSUFFIX.

QT3_UISUFFIX
Default value is '.ui'. Suffix of designer input files.


Changed in 4.5.0: renamed from QT_UISUFFIX.

QT3DIR
The path to the Qt installation to build against. If not already
set, qt3 tool tries to obtain this from os.environ; if not found
there, it tries to make a guess.


Changed in 4.5.0: renamed from QTDIR.

RANLIB
The archive indexer.

RANLIBCOM
The command line used to index a static library archive.

RANLIBCOMSTR
The string displayed when a static library archive is indexed. If
this is not set, then $RANLIBCOM (the command line) is displayed.

env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

RANLIBFLAGS
General options passed to the archive indexer.

RC
The resource compiler used to build a Microsoft Visual C++
resource file.

RCCOM
The command line used to build a Microsoft Visual C++ resource
file.

RCCOMSTR
The string displayed when invoking the resource compiler to build
a Microsoft Visual C++ resource file. If this is not set, then
$RCCOM (the command line) is displayed.

RCFLAGS
The flags passed to the resource compiler by the RES builder.

RCINCFLAGS
An automatically-generated construction variable containing the
command-line options for specifying directories to be searched by
the resource compiler. The value of $RCINCFLAGS is created by
respectively prepending and appending $RCINCPREFIX and
$RCINCSUFFIX to the beginning and end of each directory in
$CPPPATH.

RCINCPREFIX
The prefix (flag) used to specify an include directory on the
resource compiler command line. This will be prepended to the
beginning of each directory in the $CPPPATH construction variable
when the $RCINCFLAGS variable is expanded.

RCINCSUFFIX
The suffix used to specify an include directory on the resource
compiler command line. This will be appended to the end of each
directory in the $CPPPATH construction variable when the
$RCINCFLAGS variable is expanded.

RDirs
A function that converts a string into a list of Dir instances by
searching the repositories.

REGSVR
The program used on Windows systems to register a newly-built DLL
library whenever the SharedLibrary builder is passed a keyword
argument of register=True.

REGSVRCOM
The command line used on Windows systems to register a
newly-built DLL library whenever the SharedLibrary builder is
passed a keyword argument of register=True.

REGSVRCOMSTR
The string displayed when registering a newly-built DLL file. If
this is not set, then $REGSVRCOM (the command line) is displayed.

REGSVRFLAGS
Flags passed to the DLL registration program on Windows systems
when a newly-built DLL library is registered. By default, this
includes the /s that prevents dialog boxes from popping up and
requiring user attention.

RMIC
The Java RMI stub compiler.

RMICCOM
The command line used to compile stub and skeleton class files
from Java classes that contain RMI implementations. Any options
specified in the $RMICFLAGS construction variable are included on
this command line.

RMICCOMSTR
The string displayed when compiling stub and skeleton class files
from Java classes that contain RMI implementations. If this is
not set, then $RMICCOM (the command line) is displayed.

env = Environment(
RMICCOMSTR="Generating stub/skeleton class files $TARGETS from $SOURCES"
)

RMICFLAGS
General options passed to the Java RMI stub compiler.

RPATH
A list of paths to search for shared libraries when running
programs. Currently only used in the GNU (gnulink), IRIX
(sgilink) and Sun (sunlink) linkers. Ignored on platforms and
toolchains that don't support it. Note that the paths added to
RPATH are not transformed by scons in any way: if you want an
absolute path, you must make it absolute yourself.

_RPATH
An automatically-generated construction variable containing the
rpath flags to be used when linking a program with shared
libraries. The value of $_RPATH is created by respectively
prepending $RPATHPREFIX and appending $RPATHSUFFIX to the
beginning and end of each directory in $RPATH.

RPATHPREFIX
The prefix used to specify a directory to be searched for shared
libraries when running programs. This will be prepended to the
beginning of each directory in the $RPATH construction variable
when the $_RPATH variable is automatically generated.

RPATHSUFFIX
The suffix used to specify a directory to be searched for shared
libraries when running programs. This will be appended to the end
of each directory in the $RPATH construction variable when the
$_RPATH variable is automatically generated.

RPCGEN
The RPC protocol compiler.

RPCGENCLIENTFLAGS
Options passed to the RPC protocol compiler when generating
client side stubs. These are in addition to any flags specified
in the $RPCGENFLAGS construction variable.

RPCGENFLAGS
General options passed to the RPC protocol compiler.

RPCGENHEADERFLAGS
Options passed to the RPC protocol compiler when generating a
header file. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

RPCGENSERVICEFLAGS
Options passed to the RPC protocol compiler when generating
server side stubs. These are in addition to any flags specified
in the $RPCGENFLAGS construction variable.

RPCGENXDRFLAGS
Options passed to the RPC protocol compiler when generating XDR
routines. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

SCANNERS
A list of the available implicit dependency scanners. New file
scanners may be added by appending to this list, although the
more flexible approach is to associate scanners with a specific
Builder. See the manpage sections "Builder Objects" and "Scanner
Objects" for more information.

SCONS_HOME
The (optional) path to the SCons library directory, initialized
from the external environment. If set, this is used to construct
a shorter and more efficient search path in the $MSVSSCONS
command line executed from C++ project files.

SHCC
The C compiler used for generating shared-library objects. See
also $CC for compiling to static objects.

SHCCCOM
The command line used to compile a C source file to a
shared-library object file. Any options specified in the
$SHCFLAGS, $SHCCFLAGS and $CPPFLAGS construction variables are
included on this command line. See also $CCCOM for compiling to
static objects.

SHCCCOMSTR
If set, the string displayed when a C source file is compiled to
a shared object file. If not set, then $SHCCCOM (the command
line) is displayed. See also $CCCOMSTR for compiling to static
objects.

env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

SHCCFLAGS
Options that are passed to the C and C++ compilers to generate
shared-library objects. See also $CCFLAGS for compiling to static
objects.

SHCFLAGS
Options that are passed to the C compiler (only; not C++) to
generate shared-library objects. See also $CFLAGS for compiling
to static objects.

SHCXX
The C++ compiler used for generating shared-library objects. See
also $CXX for compiling to static objects.

SHCXXCOM
The command line used to compile a C++ source file to a
shared-library object file. Any options specified in the
$SHCXXFLAGS and $CPPFLAGS construction variables are included on
this command line. See also $CXXCOM for compiling to static
objects.

SHCXXCOMSTR
If set, the string displayed when a C++ source file is compiled
to a shared object file. If not set, then $SHCXXCOM (the command
line) is displayed. See also $CXXCOMSTR for compiling to static
objects.

env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

SHCXXFLAGS
Options that are passed to the C++ compiler to generate
shared-library objects. See also $CXXFLAGS for compiling to
static objects.

SHDC
The name of the compiler to use when compiling D source destined
to be in a shared object. See also $DC for compiling to static
objects.

SHDCOM
The command line to use when compiling code to be part of shared
objects. See also $DCOM for compiling to static objects.

SHDCOMSTR
If set, the string displayed when a D source file is compiled to
a (shared) object file. If not set, then $SHDCOM (the command
line) is displayed. See also $DCOMSTR for compiling to static
objects.

SHDLIBVERSIONFLAGS
Extra flags added to $SHDLINKCOM when building versioned
SharedLibrary. These flags are only used when $SHLIBVERSION is
set.

SHDLINK
The linker to use when creating shared objects for code bases
include D sources. See also $DLINK for linking static objects.

SHDLINKCOM
The command line to use when generating shared objects. See also
$DLINKCOM for linking static objects.

SHDLINKFLAGS
The list of flags to use when generating a shared object. See
also $DLINKFLAGS for linking static objects.

SHELL
A string naming the shell program that will be passed to the
$SPAWN function. See the $SPAWN construction variable for more
information.

SHELL_ENV_GENERATORS
A hook allowing the execution environment to be modified prior to
the actual execution of a command line from an action via the
spawner function defined by $SPAWN. Allows substitution based on
targets and sources, as well as values from the construction
environment, adding extra environment variables, etc.

The value must be a list (or other iterable) of functions which
each generate or alter the execution environment dictionary. The
first function will be passed a copy of the initial execution
environment ($ENV in the current construction environment); the
dictionary returned by that function is passed to the next, until
the iterable is exhausted and the result returned for use by the
command spawner. The original execution environment is not
modified.

Each function provided in $SHELL_ENV_GENERATORS must accept four
arguments and return a dictionary: env is the construction
environment for this action; target is the list of targets
associated with this action; source is the list of sources
associated with this action; and shell_env is the current
dictionary after iterating any previous $SHELL_ENV_GENERATORS
functions (this can be compared to the original execution
environment, which is available as env['ENV'], to detect any
changes).

Example:

def custom_shell_env(env, target, source, shell_env):
"""customize shell_env if desired"""
if str(target[0]) == 'special_target':
shell_env['SPECIAL_VAR'] = env.subst('SOME_VAR', target=target, source=source)
return shell_env

env["SHELL_ENV_GENERATORS"] = [custom_shell_env]


Available since 4.4

SHF03
The Fortran 03 compiler used for generating shared-library
objects. You should normally set the $SHFORTRAN variable, which
specifies the default Fortran compiler for all Fortran versions.
You only need to set $SHF03 if you need to use a specific
compiler or compiler version for Fortran 03 files.

SHF03COM
The command line used to compile a Fortran 03 source file to a
shared-library object file. You only need to set $SHF03COM if you
need to use a specific command line for Fortran 03 files. You
should normally set the $SHFORTRANCOM variable, which specifies
the default command line for all Fortran versions.

SHF03COMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to a shared-library object file. If not set, then
$SHF03COM or $SHFORTRANCOM (the command line) is displayed.

SHF03FLAGS
Options that are passed to the Fortran 03 compiler to generated
shared-library objects. You only need to set $SHF03FLAGS if you
need to define specific user options for Fortran 03 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

SHF03PPCOM
The command line used to compile a Fortran 03 source file to a
shared-library object file after first running the file through
the C preprocessor. Any options specified in the $SHF03FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $SHF03PPCOM if you need to use a
specific C-preprocessor command line for Fortran 03 files. You
should normally set the $SHFORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

SHF03PPCOMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF03PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF08
The Fortran 08 compiler used for generating shared-library
objects. You should normally set the $SHFORTRAN variable, which
specifies the default Fortran compiler for all Fortran versions.
You only need to set $SHF08 if you need to use a specific
compiler or compiler version for Fortran 08 files.

SHF08COM
The command line used to compile a Fortran 08 source file to a
shared-library object file. You only need to set $SHF08COM if you
need to use a specific command line for Fortran 08 files. You
should normally set the $SHFORTRANCOM variable, which specifies
the default command line for all Fortran versions.

SHF08COMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to a shared-library object file. If not set, then
$SHF08COM or $SHFORTRANCOM (the command line) is displayed.

SHF08FLAGS
Options that are passed to the Fortran 08 compiler to generated
shared-library objects. You only need to set $SHF08FLAGS if you
need to define specific user options for Fortran 08 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

SHF08PPCOM
The command line used to compile a Fortran 08 source file to a
shared-library object file after first running the file through
the C preprocessor. Any options specified in the $SHF08FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $SHF08PPCOM if you need to use a
specific C-preprocessor command line for Fortran 08 files. You
should normally set the $SHFORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

SHF08PPCOMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF08PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF77
The Fortran 77 compiler used for generating shared-library
objects. You should normally set the $SHFORTRAN variable, which
specifies the default Fortran compiler for all Fortran versions.
You only need to set $SHF77 if you need to use a specific
compiler or compiler version for Fortran 77 files.

SHF77COM
The command line used to compile a Fortran 77 source file to a
shared-library object file. You only need to set $SHF77COM if you
need to use a specific command line for Fortran 77 files. You
should normally set the $SHFORTRANCOM variable, which specifies
the default command line for all Fortran versions.

SHF77COMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to a shared-library object file. If not set, then
$SHF77COM or $SHFORTRANCOM (the command line) is displayed.

SHF77FLAGS
Options that are passed to the Fortran 77 compiler to generated
shared-library objects. You only need to set $SHF77FLAGS if you
need to define specific user options for Fortran 77 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

SHF77PPCOM
The command line used to compile a Fortran 77 source file to a
shared-library object file after first running the file through
the C preprocessor. Any options specified in the $SHF77FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $SHF77PPCOM if you need to use a
specific C-preprocessor command line for Fortran 77 files. You
should normally set the $SHFORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

SHF77PPCOMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF77PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF90
The Fortran 90 compiler used for generating shared-library
objects. You should normally set the $SHFORTRAN variable, which
specifies the default Fortran compiler for all Fortran versions.
You only need to set $SHF90 if you need to use a specific
compiler or compiler version for Fortran 90 files.

SHF90COM
The command line used to compile a Fortran 90 source file to a
shared-library object file. You only need to set $SHF90COM if you
need to use a specific command line for Fortran 90 files. You
should normally set the $SHFORTRANCOM variable, which specifies
the default command line for all Fortran versions.

SHF90COMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to a shared-library object file. If not set, then
$SHF90COM or $SHFORTRANCOM (the command line) is displayed.

SHF90FLAGS
Options that are passed to the Fortran 90 compiler to generated
shared-library objects. You only need to set $SHF90FLAGS if you
need to define specific user options for Fortran 90 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

SHF90PPCOM
The command line used to compile a Fortran 90 source file to a
shared-library object file after first running the file through
the C preprocessor. Any options specified in the $SHF90FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $SHF90PPCOM if you need to use a
specific C-preprocessor command line for Fortran 90 files. You
should normally set the $SHFORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

SHF90PPCOMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF90PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF95
The Fortran 95 compiler used for generating shared-library
objects. You should normally set the $SHFORTRAN variable, which
specifies the default Fortran compiler for all Fortran versions.
You only need to set $SHF95 if you need to use a specific
compiler or compiler version for Fortran 95 files.

SHF95COM
The command line used to compile a Fortran 95 source file to a
shared-library object file. You only need to set $SHF95COM if you
need to use a specific command line for Fortran 95 files. You
should normally set the $SHFORTRANCOM variable, which specifies
the default command line for all Fortran versions.

SHF95COMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to a shared-library object file. If not set, then
$SHF95COM or $SHFORTRANCOM (the command line) is displayed.

SHF95FLAGS
Options that are passed to the Fortran 95 compiler to generated
shared-library objects. You only need to set $SHF95FLAGS if you
need to define specific user options for Fortran 95 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default
Fortran compiler for all Fortran versions.

SHF95PPCOM
The command line used to compile a Fortran 95 source file to a
shared-library object file after first running the file through
the C preprocessor. Any options specified in the $SHF95FLAGS and
$CPPFLAGS construction variables are included on this command
line. You only need to set $SHF95PPCOM if you need to use a
specific C-preprocessor command line for Fortran 95 files. You
should normally set the $SHFORTRANPPCOM variable, which specifies
the default C-preprocessor command line for all Fortran versions.

SHF95PPCOMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF95PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHFORTRAN
The default Fortran compiler used for generating shared-library
objects.

SHFORTRANCOM
The command line used to compile a Fortran source file to a
shared-library object file. By default, any options specified in
the $SHFORTRANFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS
construction variables are included on this command line. See
also $FORTRANCOM.

SHFORTRANCOMSTR
If set, the string displayed when a Fortran source file is
compiled to a shared-library object file. If not set, then
$SHFORTRANCOM (the command line) is displayed.

SHFORTRANFLAGS
Options that are passed to the Fortran compiler to generate
shared-library objects.

SHFORTRANPPCOM
The command line used to compile a Fortran source file to a
shared-library object file after first running the file through
the C preprocessor. By default, any options specified in the
$SHFORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and
$_FORTRANINCFLAGS construction variables are included on this
command line. See also $SHFORTRANCOM.

SHFORTRANPPCOMSTR
If set, the string displayed when a Fortran source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHFORTRANPPCOM
(the command line) is displayed.

SHLIBEMITTER
Contains the emitter specification for the SharedLibrary builder.
The manpage section "Builder Objects" contains general
information on specifying emitters.

SHLIBNOVERSIONSYMLINKS
Instructs the SharedLibrary builder to not create symlinks for
versioned shared libraries.

SHLIBPREFIX
The prefix used for shared library file names.

_SHLIBSONAME
A macro that automatically generates shared library's SONAME
based on $TARGET, $SHLIBVERSION and $SHLIBSUFFIX. Used by
SharedLibrary builder when the linker tool supports SONAME (e.g.
gnulink).

SHLIBSUFFIX
The suffix used for shared library file names.

SHLIBVERSION
When this construction variable is defined, a versioned shared
library is created by the SharedLibrary builder. This activates
the $_SHLIBVERSIONFLAGS and thus modifies the $SHLINKCOM as
required, adds the version number to the library name, and
creates the symlinks that are needed. $SHLIBVERSION versions
should exist as alphanumeric, decimal-delimited values as defined
by the regular expression "\w+[\.\w+]*". Example $SHLIBVERSION
values include '1', '1.2.3', and '1.2.gitaa412c8b'.

_SHLIBVERSIONFLAGS
This macro automatically introduces extra flags to $SHLINKCOM
when building versioned SharedLibrary (that is when $SHLIBVERSION
is set). _SHLIBVERSIONFLAGS usually adds $SHLIBVERSIONFLAGS and
some extra dynamically generated options (such as
-Wl,-soname=$_SHLIBSONAME. It is unused by "plain" (unversioned)
shared libraries.

SHLIBVERSIONFLAGS
Extra flags added to $SHLINKCOM when building versioned
SharedLibrary. These flags are only used when $SHLIBVERSION is
set.

SHLINK
The linker for programs that use shared libraries. See also $LINK
for linking static objects.

On POSIX systems (those using the link tool), you should normally
not change this value as it defaults to a "smart" linker tool
which selects a compiler driver matching the type of source files
in use. So for example, if you set $SHCXX to a specific compiler
name, and are compiling C++ sources, the smartlink function will
automatically select the same compiler for linking.

SHLINKCOM
The command line used to link programs using shared libraries.
See also $LINKCOM for linking static objects.

SHLINKCOMSTR
The string displayed when programs using shared libraries are
linked. If this is not set, then $SHLINKCOM (the command line) is
displayed. See also $LINKCOMSTR for linking static objects.

env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

SHLINKFLAGS
General user options passed to the linker for programs using
shared libraries. Note that this variable should not contain -l
(or similar) options for linking with the libraries listed in
$LIBS, nor -L (or similar) include search path options that scons
generates automatically from $LIBPATH. See $_LIBFLAGS above, for
the variable that expands to library-link options, and
$_LIBDIRFLAGS above, for the variable that expands to library
search path options. See also $LINKFLAGS for linking static
objects.

SHOBJPREFIX
The prefix used for shared object file names.

SHOBJSUFFIX
The suffix used for shared object file names.

SONAME
Variable used to hard-code SONAME for versioned shared
library/loadable module.

env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SONAME='libtest.so.2')

The variable is used, for example, by gnulink linker tool.

SOURCE
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

SOURCE_URL
The URL (web address) of the location from which the project was
retrieved. This is used to fill in the Source: field in the
controlling information for Ipkg and RPM packages.

See the Package builder.

SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

SOVERSION
This will construct the SONAME using on the base library name
(test in the example below) and use specified SOVERSION to create
SONAME.

env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SOVERSION='2')

The variable is used, for example, by gnulink linker tool.

In the example above SONAME would be libtest.so.2 which would be
a symlink and point to libtest.so.0.1.2

SPAWN
A command interpreter function that will be called to execute
command line strings. The function must accept five arguments:

def spawn(shell, escape, cmd, args, env):


shell is a string naming the shell program to use, escape is a
function that can be called to escape shell special characters in
the command line, cmd is the path to the command to be executed,
args holds the arguments to the command and env is a dictionary
of environment variables defining the execution environment in
which the command should be executed.

STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME
When this variable is true, static objects and shared objects are
assumed to be the same; that is, SCons does not check for linking
static objects into a shared library.

SUBST_DICT
The dictionary used by the Substfile or Textfile builders for
substitution values. It can be anything acceptable to the dict()
constructor, so in addition to a dictionary, lists of tuples are
also acceptable.

SUBSTFILEPREFIX
The prefix used for Substfile file names, an empty string by
default.

SUBSTFILESUFFIX
The suffix used for Substfile file names, an empty string by
default.

SUMMARY
A short summary of what the project is about. This is used to
fill in the Summary: field in the controlling information for
Ipkg and RPM packages, and as the Description: field in MSI
packages.

See the Package builder.

SWIG
The name of the SWIG compiler to use.

SWIGCFILESUFFIX
The suffix that will be used for intermediate C source files
generated by SWIG. The default value is '_wrap$CFILESUFFIX' -
that is, the concatenation of the string _wrap and the current C
suffix $CFILESUFFIX. By default, this value is used whenever the
-c++ option is not specified as part of the $SWIGFLAGS
construction variable.

SWIGCOM
The command line used to call SWIG.

SWIGCOMSTR
The string displayed when calling SWIG. If this is not set, then
$SWIGCOM (the command line) is displayed.

SWIGCXXFILESUFFIX
The suffix that will be used for intermediate C++ source files
generated by SWIG. The default value is '_wrap$CXXFILESUFFIX' -
that is, the concatenation of the string _wrap and the current
C++ suffix $CXXFILESUFFIX. By default, this value is used
whenever the -c++ option is specified as part of the $SWIGFLAGS
construction variable.

SWIGDIRECTORSUFFIX
The suffix that will be used for intermediate C++ header files
generated by SWIG. These are only generated for C++ code when the
SWIG 'directors' feature is turned on. The default value is
_wrap.h.

SWIGFLAGS
General options passed to SWIG. This is where you should set the
target language (-python, -perl5, -tcl, etc.) and whatever other
options you want to specify to SWIG, such as the -c++ to generate
C++ code instead of C Code.

_SWIGINCFLAGS
An automatically-generated construction variable containing the
SWIG command-line options for specifying directories to be
searched for included files. The value of $_SWIGINCFLAGS is
created by respectively prepending and appending $SWIGINCPREFIX
and $SWIGINCSUFFIX to the beginning and end of each directory in
$SWIGPATH.

SWIGINCPREFIX
The prefix used to specify an include directory on the SWIG
command line. This will be prepended to the beginning of each
directory in the $SWIGPATH construction variable when the
$_SWIGINCFLAGS variable is automatically generated.

SWIGINCSUFFIX
The suffix used to specify an include directory on the SWIG
command line. This will be appended to the end of each directory
in the $SWIGPATH construction variable when the $_SWIGINCFLAGS
variable is automatically generated.

SWIGOUTDIR
Specifies the output directory in which SWIG should place
generated language-specific files. This will be used by SCons to
identify the files that will be generated by the SWIG call, and
translated into the swig -outdir option on the command line.

SWIGPATH
The list of directories that SWIG will search for included files.
SCons' SWIG implicit dependency scanner will search these
directories for include files. The default value is an empty
list.

Don't explicitly put include directory arguments in $SWIGFLAGS
the result will be non-portable and the directories will not be
searched by the dependency scanner. Note: directory names in
$SWIGPATH will be looked-up relative to the SConscript directory
when they are used in a command. To force scons to lookup a
directory relative to the root of the source tree, use a
top-relative path (#):

env = Environment(SWIGPATH='#/include')

The directory lookup can also be forced using the Dir() function:

include = Dir('include')
env = Environment(SWIGPATH=include)

The directory list will be added to command lines through the
automatically-generated $_SWIGINCFLAGS construction variable,
which is constructed by respectively prepending and appending the
values of the $SWIGINCPREFIX and $SWIGINCSUFFIX construction
variables to the beginning and end of each directory in
$SWIGPATH. Any command lines you define that need the SWIGPATH
directory list should include $_SWIGINCFLAGS:

env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SOURCES")

SWIGVERSION
The detected version string of the SWIG tool.

TAR
The tar archiver.

TARCOM
The command line used to call the tar archiver.

TARCOMSTR
The string displayed when archiving files using the tar archiver.
If this is not set, then $TARCOM (the command line) is displayed.

env = Environment(TARCOMSTR = "Archiving $TARGET")

TARFLAGS
General options passed to the tar archiver.

TARGET
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

TARGET_ARCH
The name of the hardware architecture that objects created using
this construction environment should target. Can be set when
creating a construction environment by passing as a keyword
argument in the Environment call.

On the win32 platform, if the Microsoft Visual C++ compiler is
available, msvc tool setup is done using $HOST_ARCH and
$TARGET_ARCH. If a value is not specified, will be set to the
same value as $HOST_ARCH. Changing the value after the
environment is initialized will not cause the tool to be
reinitialized. Compiled objects will be in the target
architecture if the compilation system supports generating for
that target. The latest compiler which can fulfill the
requirement will be selected, unless a different version is
directed by the value of the $MSVC_VERSION construction variable.

On the win32/msvc combination, valid target arch values are x86,
arm, i386 for 32-bit targets and amd64, arm64, x86_64 and ia64
(Itanium) for 64-bit targets. For example, if you want to compile
64-bit binaries, you would set TARGET_ARCH='x86_64' when creating
the construction environment. Note that not all target
architectures are supported for all Visual Studio / MSVC
versions. Check the relevant Microsoft documentation.


$TARGET_ARCH is not currently used by other compilation tools,
but the option is reserved to do so in future

TARGET_OS
The name of the operating system that objects created using this
construction environment should target. Can be set when creating
a construction environment by passing as a keyword argument in
the Environment call;.


$TARGET_OS is not currently used by SCons but the option is
reserved to do so in future

TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

TARSUFFIX
The suffix used for tar file names.

TEMPFILE
Holds a callable object which will be invoked to transform long
command lines (string or list) into an alternate form. Length
limits on various operating systems may cause long command lines
to fail when calling out to a shell to run the command. Most
often affects linking, when there are many object files and/or
libraries to be linked, but may also affect other compilation
steps which have many arguments. $TEMPFILE is not called
directly, but rather is typically embedded in another
construction variable, to be expanded when used. Example:

env["TEMPFILE"] = TempFileMunge
env["LINKCOM"] = "${TEMPFILE('$LINK $TARGET $SOURCES', '$LINKCOMSTR')}"

The SCons default value for $TEMPFILE, TempFileMunge, performs
command substitution on the passed command line, calculates
whether modification is needed, then puts all but the first word
(assumed to be the command name) of the resulting list into a
temporary file (sometimes called a response file or command
file), and returns a new command line consisting of the the
command name and an appropriately formatted reference to the
temporary file.

A replacement for the default tempfile object would need to do
fundamentally the same thing, including taking into account the
values of $MAXLINELENGTH, $TEMPFILEPREFIX, $TEMPFILESUFFIX,
$TEMPFILEARGJOIN, $TEMPFILEDIR and $TEMPFILEARGESCFUNC. If a
particular use case requires a different transformation than the
default, it is recommended to copy the mechanism and define a new
construction variable and rewrite the relevant *COM variable(s)
to use it, to avoid possibly disrupting existing uses of
$TEMPFILE.

TEMPFILEARGESCFUNC
The default argument escape function is SCons.Subst.quote_spaces.
If you need to apply extra operations on a command argument (to
fix Windows slashes, normalize paths, etc.) before writing to the
temporary file, you can set the $TEMPFILEARGESCFUNC variable to a
custom function. Such a function takes a single string argument
and returns a new string with any modifications applied. Example:

import sys
import re
from SCons.Subst import quote_spaces

WINPATHSEP_RE = re.compile(r"\\([^\"'\\]|$)")

def tempfile_arg_esc_func(arg):
arg = quote_spaces(arg)
if sys.platform != "win32":
return arg
# GCC requires double Windows slashes, let's use UNIX separator
return WINPATHSEP_RE.sub(r"/\1", arg)

env["TEMPFILEARGESCFUNC"] = tempfile_arg_esc_func

TEMPFILEARGJOIN
The string to use to join the arguments passed to $TEMPFILE when
the command line exceeds the limit set by $MAXLINELENGTH. The
default value is a space. However for MSVC, MSLINK the default is
a line separator as defined by os.linesep. Note this value is
used literally and not expanded by the subst logic.

TEMPFILEDIR
The directory to create the long-lines temporary file in. If
unset, some suitable default should be chosen. The default
tempfile object lets the Python tempfile module choose.

TEMPFILEPREFIX
The prefix for the name of the temporary file used to store
command lines exceeding $MAXLINELENGTH. The prefix must include
the compiler syntax to actually include and process the file. The
default prefix is '@', which works for the Microsoft Visual C++
and GNU toolchains on Windows. Set this appropriately for other
toolchains, for example '-@' for the diab compiler or '-via' for
ARM toolchain.

TEMPFILESUFFIX
The suffix for the name of the temporary file used to store
command lines exceeding $MAXLINELENGTH. The suffix should include
the dot ('.') if one is needed as it will not be added
automatically. The default is .lnk.

TEX
The TeX formatter and typesetter.

TEXCOM
The command line used to call the TeX formatter and typesetter.

TEXCOMSTR
The string displayed when calling the TeX formatter and
typesetter. If this is not set, then $TEXCOM (the command line)
is displayed.

env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

TEXFLAGS
General options passed to the TeX formatter and typesetter.

TEXINPUTS
List of directories that the LaTeX program will search for
include directories. The LaTeX implicit dependency scanner will
search these directories for \include and \import files.

TEXTFILEPREFIX
The prefix used for Textfile file names, an empty string by
default.

TEXTFILESUFFIX
The suffix used for Textfile file names; .txt by default.

TOOLS
A list of the names of the Tool specification modules that were
actually initialized in the current construction environment.
This may be useful as a diagnostic aid to see if a tool did (or
did not) run. The value is informative and is not guaranteed to
be complete.

UNCHANGED_SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

UNCHANGED_TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

VENDOR
The person or organization who supply the packaged software. This
is used to fill in the Vendor: field in the controlling
information for RPM packages, and the Manufacturer: field in the
controlling information for MSI packages.

See the Package builder.

VERSION
The version of the project, specified as a string.

See the Package builder.

VSWHERE
Specify the location of vswhere.exe.

The vswhere.exe executable is distributed with Microsoft Visual
Studio and Build Tools since the 2017 edition, but is also
available as a standalone installation. It allows queries to
obtain detailed information about installations of 2017 and later
editions. SCons makes use of this information to determine the
state of compiler support for those editions.

Setting the $VSWHERE variable to the path to a specific
vswhere.exe binary causes SCons to use that binary. If not set,
SCons will search for one, looking in the following locations in
order, using the first found ($VSWHERE is updated with the
location):
%ProgramFiles(x86)%\Microsoft Visual Studio\Installer
%ProgramFiles%\Microsoft Visual Studio\Installer
%ChocolateyInstall%\bin
%LOCALAPPDATA%\Microsoft\WinGet\Links
%USERPROFILE%\scoop\shims
%SCOOP%\shims

Note
In order to take effect, $VSWHERE must be set before the
initial Microsoft Visual C++ compiler discovery takes place.
Discovery happens, at the latest, during the first call to
the Environment function, unless a tools list is specified
which excludes the entire Microsoft Visual C++ toolchain -
that is, omits "defaults" and any specific tool module that
refers to parts of the toolchain (msvc, mslink, masm, midl
and msvs). In this case, detection is deferred until any one
of those tool modules is invoked manually. The following two
examples illustrate this:

# VSWHERE set as Environment is created
env = Environment(VSWHERE='c:/my/path/to/vswhere')

# Initialization deferred with empty tools, triggered manually
env = Environment(tools=[])
env['VSWHERE'] = r'c:/my/vswhere/install/location/vswhere.exe'
env.Tool('msvc')
env.Tool('mslink')
env.Tool('msvs')


WINDOWS_EMBED_MANIFEST
Set to True to embed the compiler-generated manifest (normally
${TARGET}.manifest) into all Windows executables and DLLs built
with this environment, as a resource during their link step. This
is done using $MT and $MTEXECOM and $MTSHLIBCOM. See also
$WINDOWS_INSERT_MANIFEST.

WINDOWS_INSERT_DEF
If set to true, a library build of a Windows shared library (.dll
file) will include a reference to the corresponding
module-definition file at the same time, if a module-definition
file is not already listed as a build target. The name of the
module-definition file will be constructed from the base name of
the library and the construction variables $WINDOWSDEFSUFFIX and
$WINDOWSDEFPREFIX. The default is to not add a module-definition
file. The module-definition file is not created by this
directive, and must be supplied by the developer.

WINDOWS_INSERT_MANIFEST
If set to true, scons will add the manifest file generated by
Microsoft Visual C++ 8.0 and later to the target list so SCons
will be aware they were generated. In the case of an executable,
the manifest file name is constructed using
$WINDOWSPROGMANIFESTSUFFIX and $WINDOWSPROGMANIFESTPREFIX. In the
case of a shared library, the manifest file name is constructed
using $WINDOWSSHLIBMANIFESTSUFFIX and
$WINDOWSSHLIBMANIFESTPREFIX. See also $WINDOWS_EMBED_MANIFEST.

WINDOWSDEFPREFIX
The prefix used for a Windows linker module-definition file name.
Defaults to empty.

WINDOWSDEFSUFFIX
The suffix used for a Windows linker module-definition file name.
Defaults to .def.

WINDOWSEXPPREFIX
The prefix used for Windows linker exports file names. Defaults
to empty.

WINDOWSEXPSUFFIX
The suffix used for Windows linker exports file names. Defaults
to .exp.

WINDOWSPROGMANIFESTPREFIX
The prefix used for executable program manifest files generated
by Microsoft Visual C++. Defaults to empty.

WINDOWSPROGMANIFESTSUFFIX
The suffix used for executable program manifest files generated
by Microsoft Visual C++. Defaults to .manifest.

WINDOWSSHLIBMANIFESTPREFIX
The prefix used for shared library manifest files generated by
Microsoft Visual C++. Defaults to empty.

WINDOWSSHLIBMANIFESTSUFFIX
The suffix used for shared library manifest files generated by
Microsoft Visual C++. Defaults to .manifest.

X_IPK_DEPENDS
This is used to fill in the Depends: field in the controlling
information for Ipkg packages.

See the Package builder.

X_IPK_DESCRIPTION
This is used to fill in the Description: field in the controlling
information for Ipkg packages. The default value is
"$SUMMARY\n$DESCRIPTION"

X_IPK_MAINTAINER
This is used to fill in the Maintainer: field in the controlling
information for Ipkg packages.

X_IPK_PRIORITY
This is used to fill in the Priority: field in the controlling
information for Ipkg packages.

X_IPK_SECTION
This is used to fill in the Section: field in the controlling
information for Ipkg packages.

X_MSI_LANGUAGE
This is used to fill in the Language: attribute in the
controlling information for MSI packages.

See the Package builder.

X_MSI_LICENSE_TEXT
The text of the software license in RTF format. Carriage return
characters will be replaced with the RTF equivalent \\par.

See the Package builder.

X_MSI_UPGRADE_CODE
TODO

X_RPM_AUTOREQPROV
This is used to fill in the AutoReqProv: field in the RPM .spec
file.

See the Package builder.

X_RPM_BUILD
internal, but overridable

X_RPM_BUILDREQUIRES
This is used to fill in the BuildRequires: field in the RPM .spec
file. Note this should only be used on a host managed by rpm as
the dependencies will not be resolvable at build time otherwise.

X_RPM_BUILDROOT
internal, but overridable

X_RPM_CLEAN
internal, but overridable

X_RPM_CONFLICTS
This is used to fill in the Conflicts: field in the RPM .spec
file.

X_RPM_DEFATTR
This value is used as the default attributes for the files in the
RPM package. The default value is "(-,root,root)".

X_RPM_DISTRIBUTION
This is used to fill in the Distribution: field in the RPM .spec
file.

X_RPM_EPOCH
This is used to fill in the Epoch: field in the RPM .spec file.

X_RPM_EXCLUDEARCH
This is used to fill in the ExcludeArch: field in the RPM .spec
file.

X_RPM_EXLUSIVEARCH
This is used to fill in the ExclusiveArch: field in the RPM .spec
file.

X_RPM_EXTRADEFS
A list used to supply extra definitions or flags to be added to
the RPM .spec file. Each item is added as-is with a carriage
return appended. This is useful if some specific RPM feature not
otherwise anticipated by SCons needs to be turned on or off. Note
if this variable is omitted, SCons will by default supply the
value '%global debug_package %{nil}' to disable debug package
generation. To enable debug package generation, include this
variable set either to None, or to a custom list that does not
include the default line.


New in version 3.1.

env.Package(
NAME="foo",
...
X_RPM_EXTRADEFS=[
"%define _unpackaged_files_terminate_build 0"
"%define _missing_doc_files_terminate_build 0"
],
...
)

X_RPM_GROUP
This is used to fill in the Group: field in the RPM .spec file.

X_RPM_GROUP_lang
This is used to fill in the Group(lang): field in the RPM .spec
file. Note that lang is not literal and should be replaced by the
appropriate language code.

X_RPM_ICON
This is used to fill in the Icon: field in the RPM .spec file.

X_RPM_INSTALL
internal, but overridable

X_RPM_PACKAGER
This is used to fill in the Packager: field in the RPM .spec
file.

X_RPM_POSTINSTALL
This is used to fill in the %post: section in the RPM .spec file.

X_RPM_POSTUNINSTALL
This is used to fill in the %postun: section in the RPM .spec
file.

X_RPM_PREFIX
This is used to fill in the Prefix: field in the RPM .spec file.

X_RPM_PREINSTALL
This is used to fill in the %pre: section in the RPM .spec file.

X_RPM_PREP
internal, but overridable

X_RPM_PREUNINSTALL
This is used to fill in the %preun: section in the RPM .spec
file.

X_RPM_PROVIDES
This is used to fill in the Provides: field in the RPM .spec
file.

X_RPM_REQUIRES
This is used to fill in the Requires: field in the RPM .spec
file.

X_RPM_SERIAL
This is used to fill in the Serial: field in the RPM .spec file.

X_RPM_URL
This is used to fill in the Url: field in the RPM .spec file.

XGETTEXT
Path to xgettext(1) program (found via Detect()). See xgettext
tool and POTUpdate builder.

XGETTEXTCOM
Complete xgettext command line. See xgettext tool and POTUpdate
builder.

XGETTEXTCOMSTR
A string that is shown when xgettext(1) command is invoked
(default: '', which means "print $XGETTEXTCOM"). See xgettext
tool and POTUpdate builder.

_XGETTEXTDOMAIN
Internal "macro". Generates xgettext domain name form source and
target (default: '${TARGET.filebase}').

XGETTEXTFLAGS
Additional flags to xgettext(1). See xgettext tool and POTUpdate
builder.

XGETTEXTFROM
Name of file containing list of xgettext(1)'s source files.
Autotools' users know this as POTFILES.in so they will in most
cases set XGETTEXTFROM="POTFILES.in" here. The $XGETTEXTFROM
files have same syntax and semantics as the well known GNU
POTFILES.in. See xgettext tool and POTUpdate builder.

_XGETTEXTFROMFLAGS
Internal "macro". Generates list of -D<dir> flags from the
$XGETTEXTPATH list.

XGETTEXTFROMPREFIX
This flag is used to add single $XGETTEXTFROM file to
xgettext(1)'s command line (default: '-f').

XGETTEXTFROMSUFFIX
(default: '')

XGETTEXTPATH
List of directories, there xgettext(1) will look for source files
(default: []).

Note
This variable works only together with $XGETTEXTFROM
See also xgettext tool and POTUpdate builder.

_XGETTEXTPATHFLAGS
Internal "macro". Generates list of -f<file> flags from
$XGETTEXTFROM.

XGETTEXTPATHPREFIX
This flag is used to add single search path to xgettext(1)'s
command line (default: '-D').

XGETTEXTPATHSUFFIX
(default: '')

YACC
The parser generator.

YACC_GRAPH_FILE
If supplied, write a graph of the automaton to a file with the
name taken from this variable. Will be emitted as a --graph=
command-line option. Use this in preference to including --graph=
in $YACCFLAGS directly.

New in version 4.4.0.

YACC_GRAPH_FILE_SUFFIX
Previously specified by $YACCVCGFILESUFFIX.

The suffix of the file containing a graph of the grammar
automaton when the -g option (or --graph= without an
option-argument) is used in $YACCFLAGS. Note that setting this
variable informs SCons how to construct the graph filename for
tracking purposes, it does not affect the actual generated
filename. Various yacc tools have emitted various formats at
different times. Set this to match what your parser generator
produces.

New in version 4.6.0.

YACC_HEADER_FILE
If supplied, generate a header file with the name taken from this
variable. Will be emitted as a --header= command-line option. Use
this in preference to including --header= in $YACCFLAGS directly.

New in version 4.4.0.

YACCCOM
The command line used to call the parser generator to generate a
source file.

YACCCOMSTR
The string displayed when generating a source file using the
parser generator. If this is not set, then $YACCCOM (the command
line) is displayed.

env = Environment(YACCCOMSTR="Yacc'ing $TARGET from $SOURCES")

YACCFLAGS
General options passed to the parser generator. In addition to
passing the value on during invocation, the yacc tool also
examines this construction variable for options which cause
additional output files to be generated, and adds those to the
target list.

If the -d option is present in $YACCFLAGS scons assumes that the
call will also create a header file with the suffix defined by
$YACCHFILESUFFIX if the yacc source file ends in a .y suffix, or
a file with the suffix defined by $YACCHXXFILESUFFIX if the yacc
source file ends in a .yy suffix. The header will have the same
base name as the requested target. This is only correct if the
executable is bison (or win_bison). If using Berkeley yacc
(byacc), y.tab.h is always written - avoid the -d in this case
and use $YACC_HEADER_FILE instead.

If a -g option is present, scons assumes that the call will also
create a graph file with the suffix defined by
$YACCVCGFILESUFFIX.

If a -v option is present, scons assumes that the call will also
create an output debug file with the suffix .output.

Also recognized are GNU bison options --header (and its
deprecated synonym --defines), which is similar to -d but gives
the option to explicitly name the output header file through an
option argument; and --graph, which is similar to -g but gives
the option to explicitly name the output graph file through an
option argument. The file suffixes described for -d and -g above
are not applied if these are used in the option=argument form.

Note that files specified by --header= and --graph= may not be
properly handled by SCons in all situations, and using those in
$YACCFLAGS should be considered legacy support only. Consider
using $YACC_HEADER_FILE and $YACC_GRAPH_FILE instead if the files
need to be explicitly named (new in version 4.4.0).

YACCHFILESUFFIX
The suffix of the C header file generated by the parser generator
when the -d option (or --header without an option-argument) is
used in $YACCFLAGS. Note that setting this variable informs SCons
how to construct the header filename for tracking purposes, it
does not affect the actual generated filename. Set this to match
what your parser generator produces. The default value is .h.

YACCHXXFILESUFFIX
The suffix of the C++ header file generated by the parser
generator when the -d option (or --header without an
option-argument) is used in $YACCFLAGS. Note that setting this
variable informs SCons how to construct the header filename for
tracking purposes, it does not affect the actual generated
filename. Set this to match what your parser generator produces.
The default value is .hpp.

YACCVCGFILESUFFIX
Obsoleted. Use $YACC_GRAPH_FILE_SUFFIX instead. The value is used
only if $YACC_GRAPH_FILE_SUFFIX is not set. The default value is
.gv.


Changed in version 4.6.0: deprecated. The default value changed
from .vcg (bison stopped generating .vcg output with version 2.4,
in 2006).

ZIP
The zip compression and file packaging utility.

ZIP_OVERRIDE_TIMESTAMP
An optional timestamp which overrides the last modification time
of the file when stored inside the Zip archive. This is a tuple
of six values: Year (>= 1980) Month (one-based) Day of month
(one-based) Hours (zero-based) Minutes (zero-based) Seconds
(zero-based)

ZIPCOM
The command line used to call the zip utility, or the internal
Python function used to create a zip archive.

ZIPCOMPRESSION
The compression flag from the Python zipfile module used by the
internal Python function to control whether the zip archive is
compressed or not. The default value is zipfile.ZIP_DEFLATED,
which creates a compressed zip archive. This value has no effect
if the zipfile module is unavailable.

ZIPCOMSTR
The string displayed when archiving files using the zip utility.
If this is not set, then $ZIPCOM (the command line or internal
Python function) is displayed.

env = Environment(ZIPCOMSTR = "Zipping $TARGET")

ZIPFLAGS
General options passed to the zip utility.

ZIPROOT
An optional zip root directory (default empty). The filenames
stored in the zip file will be relative to this directory, if
given. Otherwise, the filenames are relative to the current
directory of the command. For instance:

env = Environment()
env.Zip('foo.zip', 'subdir1/subdir2/file1', ZIPROOT='subdir1')

will produce a zip file foo.zip containing a file with the name
subdir2/file1 rather than subdir1/subdir2/file1.

ZIPSUFFIX
The suffix used for zip file names.

Configure Contexts

SCons supports a configure context, an integrated mechanism similar
to the various AC_CHECK macros in GNU Autoconf for testing the
existence of external items needed for the build, such as C header
files, libraries, etc. The mechanism is portable across platforms.

scons does not maintain an explicit cache of the tested values (this
is different than Autoconf), but uses its normal dependency tracking
to keep the checked values up to date. However, users may override
this behavior with the --config command line option.

Configure(env, [custom_tests, conf_dir, log_file, config_h, clean,
help]), env.Configure([custom_tests, conf_dir, log_file, config_h,
clean, help])
Create a configure context, which tracks information discovered
while running tests. The context includes a local construction
environment (available as context.env) which is used when running
the tests and which can be updated with the check results. Only
one context may be active at a time, but a new context can be
created after the active one is completed. For the global
function form, the required env describes the initial values for
the context's local construction environment; for the
construction environment method form the instance provides the
values.


Changed in version 4.0: raises an exception on an attempt to
create a new context when there is an active context.

custom_tests specifies a dictionary containing custom checks (see
details below). The default value is None, to indicate there are
no custom checks in the configure context.


conf_dir specifies a directory where the test cases are built.
This directory is not used for building normal targets. The
default value is "#/.sconf_temp".


log_file specifies a file which collects the output from commands
that are executed to check for the existence of header files,
libraries, etc. The default is "#/config.log". If you are using
variant directories, you may want to place the log file for a
given build under that build's variant directory.


config_h specifies a C header file where the results of tests
will be written. The results will consist of lines like #define
HAVE_STDIO_H, #define HAVE_LIBM, etc. Customarily, the name
chosen is "config.h". The default is to not write a config_h
file. You can specify the same config_h file in multiple calls to
Configure, in which case SCons will concatenate all results in
the specified file. Note that SCons uses its normal dependency
checking to decide if it's necessary to rebuild the specified
config_h file. This means that the file is not necessarily
re-built each time scons is run, but is only rebuilt if its
contents will have changed and some target that depends on the
config_h file is being built.

The clean and help arguments can be used to suppress execution of
the configuration tests when the -c/--clean or -H/-h/--help
options are used, respectively. The default behavior is always to
execute configure context tests, since the results of the tests
may affect the list of targets to be cleaned or the help text. If
the configure tests do not affect these, then you may add the
clean=False or help=False arguments (or both) to avoid
unnecessary test execution.

context.Finish()
This method must be called after configuration is done. Though
required, this is not enforced except if Configure is called
again while there is still an active context, in which case an
exception is raised. Finish returns the environment as modified
during the course of running the configuration checks. After this
method is called, no further checks can be performed with this
configuration context. However, you can create a new configure
context to perform additional checks.

Example of a typical Configure usage:

env = Environment()
conf = Configure(env)
if not conf.CheckCHeader("math.h"):
print("We really need math.h!")
Exit(1)
if conf.CheckLibWithHeader("qt", "qapp.h", "c++", "QApplication qapp(0,0);"):
# do stuff for qt - usage, e.g.
conf.env.Append(CPPDEFINES="WITH_QT")
env = conf.Finish()

A configure context has the following predefined methods which can be
used to perform checks. Where language is an optional parameter, it
specifies the compiler to use for the check, currently a choice of C
or C++. The spellings accepted for C are "C" or "c"; for C++ the
value can be "CXX", "cxx", "C++" or "c++". If language is omitted,
"C" is assumed.

context.CheckHeader(header, [include_quotes, language])
Checks if header is usable in the specified language. header may
be a list, in which case the last item in the list is the header
file to be checked, and the previous list items are header files
whose #include lines should precede the header line being checked
for. The optional argument include_quotes must be a two character
string, where the first character denotes the opening quote and
the second character denotes the closing quote. By default, both
characters are " (double quote).

Returns a boolean indicating success or failure.

context.CheckCHeader(header, [include_quotes])
Checks if header is usable when compiling a C language program.
header may be a list, in which case the last item in the list is
the header file to be checked, and the previous list items are
header files whose #include lines should precede the header line
being checked for. The optional argument include_quotes must be a
two character string, where the first character denotes the
opening quote and the second character denotes the closing quote.
By default, both characters are " (double quote). Note this is a
wrapper around CheckHeader. Returns a boolean indicating success
or failure.

context.CheckCXXHeader(header, [include_quotes])
Checks if header is usable when compiling a C++ language program.
header may be a list, in which case the last item in the list is
the header file to be checked, and the previous list items are
header files whose #include lines should precede the header line
being checked for. The optional argument include_quotes must be a
two character string, where the first character denotes the
opening quote and the second character denotes the closing quote.
By default, both characters are " (double quote). Note this is a
wrapper around CheckHeader. Returns a boolean indicating success
or failure.

context.CheckFunc(function_name, [header, language, funcargs])
Checks if function_name is usable in the context's local
environment, using the compiler specified by language - that is,
can a check referencing it be compiled using the current values
of $CFLAGS, $CPPFLAGS, $LIBS or other relevant construction
variables.

The optional header argument is a string representing a code
fragment to place at the top of the test program that will be
compiled to check if the function exists. If omitted, the default
stanza will be (with function_name appropriately substituted):

#ifdef __cplusplus
extern "C"
#endif
char function_name(void);

If header is supplied, it should not include the standard header
file that declares function_name and it should include a dummy
prototype similar to the default case. If this is not possible,
the optional funcargs argument can be used to specify a string
containing an argument list with the same number and type of
arguments as the prototype. The arguments can simply be constant
values of the correct type. Modern C/C++ compilers reject
implicit function declarations and may also reject function calls
whose arguments are not type compatible with the prototype.


Changed in version 4.7.0: added the funcargs.

Returns a boolean indicating success or failure.

context.CheckLib([library, symbol, header, language, extra_libs=None,
autoadd=True, append=True, unique=False])
Checks if library provides symbol by compiling a simple stub
program with the compiler selected by language, and optionally
adds that library to the context. If supplied, the text of header
is included at the top of the stub.

The remaining arguments should be specified in keyword style. If
extra_libs is specified, it is a list off additional libraries to
include when linking the stub program (usually, dependencies of
the library being checked). If autoadd is true (the default), and
the library provides the specified symbol, as defined by
successfully linking the stub program, it is added to the $LIBS
construction variable in the context. If append is true (the
default), the library is appended, otherwise it is prepended. If
unique is true, and the library would otherwise be added but is
already present in $LIBS in the configure context, it will not be
added again. The default is False.


library can be a list of library names, or None (the default if
the argument is omitted). If the former, symbol is checked
against each library name in order, returning (and reporting
success) on the first successful test; if the latter, it is
checked with the current value of $LIBS (in this case no library
name would be added). If symbol is omitted or None, then CheckLib
just checks if you can link against the specified library, Note
though it is legal syntax, it would not be very useful to call
this method with library and symbol both omitted or None - at
least one should be supplied.

Returns a boolean indicating success or failure.


Changed in version 4.5.0: added the append and unique parameters.


Changed in version 4.9.0: added the extra_libs parameter.

context.CheckLibWithHeader([library, header, language,
extra_libs=None, call=None, autoadd=True, append=True, unique=False])
Provides an alternative to the CheckLib method for checking
whether libraries are usable in a build. The first three
arguments can be given as positional or keyword style arguments.
library specifies a library or list of libraries to check (the
default is None), header specifies header text to include in the
test program. header may also be a list, in which case the last
item in the list is the header file to be checked, and the
previous list items are header files whose #include lines should
precede the header line being checked for. The default is to
include no header text. language indicates the compiler to use
(default "C").

The remaining parameters should be specified in keyword style. If
provided, call is a code fragment to compile as the stub test,
replacing the auto-generated stub. The fragment must be a valid
expression in language. If not supplied, the default checks the
ability to link against the specified library. extra_libs can be
used to add additional libraries to link against (usually,
dependencies of the library under test). If autoadd is true (the
default), the first library that passes the check is added to the
$LIBS construction variable in the context and the method
returns. If append is true (the default), the library is
appended, otherwise prepended. If unique is true, and the library
would otherwise be added but is already present in $LIBS in the
configure context, it will not be added again. The default is
False.

Returns a boolean indicating success or failure.


Changed in version 4.5.0: added the append and unique parameters.


Changed in version 4.9.0: added the extra_libs parameter.

context.CheckType(type_name, [includes, language])
Checks for the existence of a type defined by typedef. type_name
specifies the typedef name to check for. includes is a string
containing one or more #include lines that will be inserted into
the program that will be run to test for the existence of the
type. Example:

sconf.CheckType('foo_type', '#include "my_types.h"', 'C++')

Returns a boolean indicating success or failure.

context.CheckTypeSize(type_name, [header, language, expect])
Checks for the size of a type defined by typedef. type_name
specifies the typedef name to check for. The optional header
argument is a string that will be placed at the top of the test
file that will be compiled to check if the type exists; the
default is empty. If the optional expect, is supplied, it should
be an integer size; CheckTypeSize will fail unless type_name is
actually that size. Returns the size in bytes, or zero if the
type was not found (or if the size did not match optional
expect).

For example,

CheckTypeSize('short', expect=2)

will return the size 2 only if short is actually two bytes.

context.CheckCC()
Checks whether the C compiler (as defined by the $CC construction
variable) works, by trying to compile a small source file. This
provides a more rigorous check: by default, SCons itself only
detects if there is a program with the correct name, not if it is
a functioning compiler. Returns a boolean indicating success or
failure.

The test program will be built with the same command line as the
one used by the Object builder for C source files, so by setting
relevant construction variables it can be used to detect if
particular compiler flags will be accepted or rejected by the
compiler.

Returns a boolean indicating success or failure.

context.CheckCXX()
Checks whether the C++ compiler (as defined by the $CXX
construction variable) works, by trying to compile a small source
file. This provides a more rigorous check: by default, SCons
itself only detects if there is a program with the correct name,
not if it is a functioning compiler. Returns a boolean indicating
success or failure.

The test program will be built with the same command line as the
one used by the Object builder for C++ source files, so by
setting relevant construction variables it can be used to detect
if particular compiler flags will be accepted or rejected by the
compiler.

Returns a boolean indicating success or failure.

context.CheckSHCC()
Checks whether the shared-object C compiler (as defined by the
$SHCC construction variable) works by trying to compile a small
source file. This provides a more rigorous check: by default,
SCons itself only detects if there is a program with the correct
name, not if it is a functioning compiler. Returns a boolean
indicating success or failure.

The test program will be built with the same command line as the
one used by the SharedObject builder for C source files, so by
setting relevant construction variables it can be used to detect
if particular compiler flags will be accepted or rejected by the
compiler. Note this does not check whether a shared library/dll
can be created.

Returns a boolean indicating success or failure.

context.CheckSHCXX()
Checks whether the shared-object C++ compiler (as defined by the
$SHCXX construction variable) works by trying to compile a small
source file. This provides a more rigorous check: by default,
SCons itself only detects if there is a program with the correct
name, not if it is a functioning compiler. Returns a boolean
indicating success or failure.

The test program will be built with the same command line as the
one used by the SharedObject builder for C++ source files, so by
setting relevant construction variables it can be used to detect
if particular compiler flags will be accepted or rejected by the
compiler. Note this does not check whether a shared library/dll
can be created.

Returns a boolean indicating success or failure.

context.CheckProg(prog_name)
Checks if prog_name exists in the path SCons will use at build
time. (context.env['ENV']['PATH']). Returns a string containing
the path to the program, or None on failure.

context.CheckDeclaration(symbol, [includes, language])
Checks if the specified symbol is declared. includes is a string
containing one or more #include lines that will be inserted into
the program that will be run to test for the existence of the
symbol.

Returns a boolean indicating success or failure.

context.CheckMember(aggregate_member, [header, language])
Checks for the existence of a member of the C/C++ struct or
class. aggregate_member specifies the struct/class and member to
check for. header is a string containing one or more #include
lines that will be inserted into the program that will be run to
test for the existence of the member. Example:

sconf.CheckMember('struct tm.tm_sec', '#include <time.h>')


Returns a boolean indicating success or failure.

context.Define(symbol, [value, comment])
This method does not check for anything, but rather forces the
definition of a preprocessor macro that will be added to the
configuration header file. name is the macro's identifier. If
value is given, it will be be used as the macro replacement
value. If value is a string and needs to display with quotes, the
quotes need to be included, as in '"string"' If the optional
comment is given, it is inserted as a comment above the macro
definition (suitable comment marks will be added automatically).
This is analogous to using AC_DEFINE in Autoconf.

Examples:

env = Environment()
conf = Configure(env)

# Puts the following line in the config header file:
# #define A_SYMBOL
conf.Define("A_SYMBOL")

# Puts the following line in the config header file:
# #define A_SYMBOL 1
conf.Define("A_SYMBOL", 1)

Examples of quoting string values:

env = Environment()
conf = Configure(env)

# Puts the following line in the config header file:
# #define A_SYMBOL YA
conf.Define("A_SYMBOL", "YA")

# Puts the following line in the config header file:
# #define A_SYMBOL "YA"
conf.Define("A_SYMBOL", '"YA"')

Example including comment:

env = Environment()
conf = Configure(env)

# Puts the following lines in the config header file:
# /* Set to 1 if you have a symbol */
# #define A_SYMBOL 1
conf.Define("A_SYMBOL", 1, "Set to 1 if you have a symbol")

You can define your own custom checks in addition to using the
predefined checks. To enable custom checks, pass a dictionary to the
Configure function as the custom_tests parameter. The dictionary maps
the names of the checks to the custom check callables (either a
Python function or an instance of a class implementing a __call__
method). Each custom check will be called with a a CheckContext
instance as the first parameter followed by the remaining arguments,
which must be supplied by the user of the check. A CheckContext is
not the same as a configure context; rather it is an instance of a
class which contains a configure context (available as
chk_ctx.sconf). A CheckContext provides the following methods which
custom checks can make use of::

chk_ctx.Message(text)
Displays text as an indicator of progress. For example: Checking
for library X.... Usually called before the check is started.

chk_ctx.Result(res)
Displays a result message as an indicator of progress. If res is
an integer, displays yes if res evaluates true or no if false. If
res is a string, it is displayed as-is. Usually called after the
check has completed.

chk_ctx.TryCompile(text, extension='')
Checks if a file containing text and given the specified
extension (e.g. '.c') can be compiled to an object file using
the environment's Object builder. Returns a boolean indicating
success or failure.

chk_ctx.TryLink(text, extension='')
Checks if a file containing text and given the specified
extension (e.g. '.c') can be compiled to an executable program
using the environment's Program builder. Returns a boolean
indicating success or failure.

chk_ctx.TryRun(text, extension='')
Checks if a file containing text and given the specified
extension (e.g. '.c') can be compiled to an excutable program
using the environment's Program builder and subsequently
executed. Execution is only attempted if the build succeeds. If
the program executes successfully (that is, its return status is
0), a tuple (True, outputStr) is returned, where outputStr is the
standard output of the program. If the program fails execution
(its return status is non-zero), then (False, '') is returned.

chk_ctx.TryAction(action, [text, extension=''])
Checks if the specified action with an optional source file
(contents text, given extension extension) can be executed.
action may be anything which can be converted to an Action
Object. On success, a tuple (True, outputStr) is returned, where
outputStr is the content of the target file. On failure (False,
'') is returned.

chk_ctx.TryBuild(builder, [text, extension=''])
Low level implementation for testing specific builds; the methods
above are based on this method. Given the Builder instance
builder and the optional text of a source file with optional
extension, returns a boolean indicating success or failure. In
addition, chk_ctx.lastTarget is set to the build target node if
the build was successful.

Example of implementing and using custom checks:

def CheckQt(chk_ctx, qtdir):
chk_ctx.Message('Checking for qt ...')
lastLIBS = chk_ctx.env['LIBS']
lastLIBPATH = chk_ctx.env['LIBPATH']
lastCPPPATH = chk_ctx.env['CPPPATH']
chk_ctx.env.Append(LIBS='qt', LIBPATH=qtdir + '/lib', CPPPATH=qtdir + '/include')
ret = chk_ctx.TryLink(
"""\
#include <qapp.h>
int main(int argc, char **argv) {
QApplication qapp(argc, argv);
return 0;
}
"""
)
if not ret:
chkctx.env.Replace(LIBS=lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
chkctx.Result(ret)
return ret

env = Environment()
conf = Configure(env, custom_tests={'CheckQt': CheckQt})
if not conf.CheckQt('/usr/lib/qt'):
print('We really need qt!')
Exit(1)
env = conf.Finish()

Command-Line Construction Variables
SCons depends on information stored in construction variables to
control how targets are built. It is often necessary to pass
specialized information at build time to override the variables in
the build scripts. This can be done through variable-assignment
arguments on the command line and/or in stored variable files.

For the case where you want to specify new values for construction
variables, SCons provides a Variables object to simplify collecting
those and updating a construction environment with the values. This
helps processing commands lines like this:

scons VARIABLE=foo OTHERVAR=bar

Variables supplied on the command line can always be manually
processed by iterating the ARGUMENTS dictionary or the ARGLIST list,
However, using a Variables object allows you to describe anticipated
variables, perform necessary type conversion, validate that values
meet defined constraints, and specify default values, help messages
and aliases. This provides a somewhat similar interface to option
handling (see AddOption). A Variables object also allows obtaining
values from a saved variables file, or from a custom dictionary in an
SConscript file. The processed variables can then be applied to the
desired construction environment.

Conceptually, command-line targets control what to build,
command-line variables (and variable files) control how to build, and
command-line options control how SCons operates (although SCons does
not enforce that separation).

To obtain an object for manipulating variables, call the Variables
factory function:

Variables([files, [args]])
If files is a filename or list of filenames, they are executed as
Python scripts to set saved variables when the Update method is
called. This allows the use of Python syntax in the assignments.
A variables file can be the result of an previous call to the
Save method. If files is not specified, or the files argument is
None, then no files will be processed. Supplying None is required
if there are no files but you want to specify args as a
positional argument; or you can use keyword arguments to avoid
that. If any of files is missing, it is silently skipped.

Either of the following example file contents could be used to
set an alternative C compiler:

CC = 'my_cc'
CC = os.environ.get('CC')

If args is specified, it must be a dictionary. The key-value
pairs from args will be added to those obtained from files, if
any. Keys from args take precedence over same-named keys from
files. If omitted, the default is the ARGUMENTS dictionary that
holds build variables specified on the command line. Using
ARGUMENTS allows you to indicate that if a setting appears on
both the command line and in the file(s), the command line
setting is preferred. However, any dictionary can be passed.
Examples:

vars = Variables('custom.py')
vars = Variables('overrides.py', ARGUMENTS)
vars = Variables(None, {FOO:'expansion', BAR:7})
vars = Variables(args={FOO:'expansion', BAR:7})

Calling Variables with no arguments is equivalent to:

vars = Variables(files=None, args=ARGUMENTS)

A Variables object is a container for variable descriptions, added by
calling the Add or AddVariables methods. A variable description
consists of a name, a list of aliases for the name, a help message, a
default value, and functions to validate and convert values.
Processing of input sources is deferred until the Update method is
called, at which time the variables are added to the specified
construction environment, using the name as the construction variable
name; any aliases are not added. Variables from the input sources
which do not match any names or aliases from the variable
descriptions in this object are skipped, except that a dictionary of
their names and values are made available in the unknown attribute of
the Variables object. This list can also be obtained via the
UnknownVariables method. If a variable description has a default
value other than None and does not appear in the input sources, it is
added to the construction environment with its default value. A list
of variables set from their defaults and not from the input sources
is available as the defaulted attribute of the Variables object. The
unknown variables and defaulted information is not available until
the Update method has run.

Since the variables are eventually added as construction variables,
you should choose variable names which do not unintentionally change
pre-defined construction variables that your project will make use of
(see the section called "Construction Variables" for a reference),
since the specified values are assigned, not merged, to the
respective construction variables.

The Variables subsystem does not directly support a way to define a
variable the user must supply, but this can be simulated by using a
validator function, and specifying a default value which the
validator will reject, resulting in an invalid value error message
(the convenience methods EnumVariable and ListVariable make this
relatively straightforward).

A Variables object has the following methods:

vars.Add(key, [help, default, validator, converter, subst])
Add a customizable construction variable to the Variables object.
key is either the name of the variable, or a sequence of strings,
in which case the first item in the sequence is taken as the
variable name, and any remaining values are considered aliases
for the variable. key is mandatory, the other fields are
optional. help is the help text for the variable (defaults to an
empty string). default is the default value of the variable
(defaults to None). The variable will be set to the value of
default if it does not appear in the input sources, except if
default is None, in which case it is not added to the
construction environment unless it has been set in the input
sources.

If the validator argument is supplied, it is a callback function
to validate the value of the variable when the variables are
processed (that is, when the Update method runs). A validator
function must accept three arguments: key, value and env, and
should raise an exception (with a helpful error message) if value
is invalid. No return value is expected from the validator.

If the converter argument is supplied, it is a callback function
to convert the value into one suitable for adding to the
construction environment. A converter function must accept the
value argument, and may declare env as a second argument if it
needs access to the construction environment while validating -
the function will be called appropriately. The converter is
called before the validator; it must return a value, which is
then passed to the validator (if any) for checking. In general,
the converter should not fail, leaving validation checks to the
validator, although if an operation is impossible to complete or
there is no separate validator it can raise a ValueError.

Substitution will be performed on the variable value before the
converter and validator are called, unless the optional subst
parameter is false (the default is True). Suppressing
substitution may be useful if the variable value looks like a
construction variable reference (e.g. $VAR) and the validator
and/or converter should see it unexpanded.

As a special case, if key is a sequence and is the only argument
to Add, it is unpacked into the five parameters key, help,
default, validator and converter, with any missing members from
the right filled in with the respective default values. This form
allows it to consume a tuple emitted by the convenience functions
BoolVariable, EnumVariable, ListVariable, PackageVariable and
PathVariable.

Examples:

vars.Add('CC', help='The C compiler')

def valid_color(key, val, env):
if not val in ['red', 'blue', 'yellow']:
raise Exception("Invalid color value '%s'" % val)

vars.Add('COLOR', validator=valid_color)


Changed in version 4.8.0: added the subst parameter.

vars.AddVariables(args)
A convenience method that adds one or more customizable
construction variables to a Variables object in one call;
equivalent to calling Add multiple times. Each args member must
be a tuple that contains the arguments for an individual call to
the Add method using the "special case" form; the other calling
styles (individual positional arguments and/or keyword arguments)
are not supported.

opt.AddVariables(
("debug", "", 0),
("CC", "The C compiler"),
("VALIDATE", "An option for testing validation", "notset", validator, None),
)

vars.FormatVariableHelpText(env, opt, help, default, actual, aliases)
Returns a formatted string containing the printable help text for
the single variable opt. All of the arguments must be supplied
except aliases, which is optional. env is the construction
environment containing the variable values, (env is not used by
the standard implementation of FormatVariableHelpText); var is
the name of the variable; help is the text of the initial help
message when the variable was added to the Variables object;
default is the default value assigned when the variable was added
to the Variables object; actual is the value as assigned in env
(which may be the same as default, if none of the input sources
assign to the variable); and aliases are any alias names for the
variable, if omitted defaults to an empty list.


FormatVariableHelpText is normally not called directly, but by
GenerateHelpText, which does the work of obtaining the necessary
values. You can patch in your own function that takes the same
function signature in order to customize the appearance of
variable help messages. Example:

def my_format(env, var, help, default, actual):
fmt = "\n%s: default=%s actual=%s (%s)\n"
return fmt % (var, default, actual, help)

vars.FormatVariableHelpText = my_format

Note that GenerateHelpText will not put any blank lines or extra
characters between the entries, so you must add those characters
to the returned string if you want the entries separated.

vars.GenerateHelpText(env, [sort])
Return a formatted string with the help text collected from all
the variables configured in this Variables object. This string is
suitable for passing in to the Help function. The generated
string include an indication of the actual value in the
environment given by env.

If the optional sort parameter is set to a callable value, it is
used as a comparison function to determine how to sort the added
variables. This function must accept two arguments, compare them,
and return a negative integer if the first is less-than the
second, zero if equal, or a positive integer if greater-than. If
sort is not callable, but evaluates true, an alphabetical sort is
performed. The default is False (unsorted).

Help(vars.GenerateHelpText(env))

def cmp(a, b):
return (a > b) - (a < b)

Help(vars.GenerateHelpText(env, sort=cmp))

vars.Save(filename, env)
Saves the currently set variables into a script file named by
filename. This provides a way to cache particular variable
settings for reuse. Only variables that are set to non-default
values are saved. You can load these saved variables on a
subsequent run by passing filename to the Variables function,

env = Environment()
vars = Variables(['variables.cache', 'custom.py'])
vars.Add(...)
vars.Update(env)
vars.Save('variables.cache', env)

vars.UnknownVariables()
Returns a dictionary containing any variables that were specified
in the files and/or args parameters when Variables was called,
but the object was not actually configured for. This information
is not available until the Update method has run.

env = Environment(variables=vars)
for key, value in vars.UnknownVariables():
print("unknown variable: %s=%s" % (key, value))

vars.Update(env, [args])
Process the input sources recorded when the Variables object was
initialized and update env with the customized construction
variables. The names of any variables in the input sources that
are not configured in the Variables object are recorded and may
be retrieved using the UnknownVariables method.

If the optional args argument is provided, it must be a
dictionary of variables, which will be used in place of the one
saved when the Variables object was created.

Normally, Update is not called directly, but rather invoked
indirectly by passing the Variables object to the Environment
function:

env = Environment(..., variables=vars)

A Variables object also makes available two data attributes that can
be read for further information. These only have values if Update has
previously run.

vars.defaulted
A list of variable names that were set in the construction
environment from the default values in the variable descriptions
- that is, variables that have a default value and were not
defined in the input sources.

vars.unknown
A dictionary of variables that were specified in the input
sources, but do not have matching variable definitions. This is
the same information that is returned by the UnknownVariables
method.

Added in 4.9.0: the defaulted attribute.

SCons provides five pre-defined variable types, accessible through
factory functions that generate a tuple appropriate for directly
passing to the Add or AddVariables methods.

BoolVariable(key, help, default)
Set up a Boolean variable named key. The variable will have a
default value of default, and help will form the descriptive part
of the help text. The variable will interpret the command-line
values y, yes, t, true, 1, on and all as true, and the
command-line values n, no, f, false, 0, off and none as false.

EnumVariable(key, help, default, allowed_values, [map, ignorecase])
Set up a variable named key whose value may only be chosen from a
specified list ("enumeration") of values. The variable will have
a default value of default and help will form the descriptive
part of the help text. Any value that is not in allowed_values
will raise an error, except that the optional map argument is a
dictionary that can be used to map additional names into a
particular name in the allowed_values list. If the optional
ignorecase is 0 (the default), the values are considered
case-sensitive. If ignorecase is 1, values will be matched
case-insensitively. If ignorecase is 2, values will be matched
case-insensitively, and all input values will be converted to
lower case.

ListVariable(key, help, default, names, [map, validator])
Set up a variable named key whose value may be one or more
choices from a specified list of values. The variable will have a
default value of default, and help will form the descriptive part
of the help text. Any value that is not in names or the special
values all or none will raise an error. Use a comma separator to
specify multiple values. default may be specified either as a
string of comma-separated values, or as a Python list of values.

The optional map argument is a dictionary that can be used to
convert input values into specific legal values in the names
list. (Note that the additional values accepted through the use
of a map are not reflected in the generated help message).

The optional validator argument can be used to specify a custom
validator callback function, as described for Add. The default is
to use an internal validator routine.

Added in 4.8.0: the validator parameter.

PackageVariable(key, help, default)
Set up a variable named key to help control a build component,
such as a software package. The variable can be specified to
disable, enable, or enable with a custom path. The resulting
construction variable will have a value of True, False, or a path
string. Interpretation of this value is up to the consumer, but a
path string must refer to an existing filesystem entry or the
PackageVariable validator will raise an exception.

Any of the (case-insensitive) strings 1, yes, true, on, enable
and search can be used to indicate the package is "enabled", and
the (case-insensitive) strings 0, no, false, off and disable to
indicate the package is "disabled".

The default parameter can be either a path string or one of the
enabling or disabling strings. default is produced if the
variable is not specified, or if it is specified with one of the
enabling strings, except that if default is one of the enabling
strings, the boolean literal True is produced instead of the
string. The help parameter specifies the descriptive part of the
help text.

PathVariable(key, help, default, [validator])
Set up a variable named key to hold a path string. The variable
will have a default value of default, and the help parameter will
be used as the descriptive part of the help text.

The optional validator parameter describes a callback function
which will be called to verify that the specified path is
acceptable. SCons supplies the following ready-made validators:

PathVariable.PathExists
Verify that the specified path exists (this the default
behavior if no validator is supplied).

PathVariable.PathIsFile
Verify that the specified path exists and is a regular file.

PathVariable.PathIsDir
Verify that the specified path exists and is a directory.

PathVariable.PathIsDirCreate
Verify that the specified path exists and is a directory; if
it does not exist, create the directory.

PathVariable.PathAccept
Accept the specific path name argument without validation,
suitable for when you want your users to be able to specify a
directory path that will be created as part of the build
process, for example.

You may supply your own validator function, which must accept
three arguments: key, the name of the variable to be set; val,
the specified value being checked; and env, the construction
environment, and should raise an exception if the specified value
is not acceptable.

These functions make it convenient to create a number of variables
with consistent behavior in a single call to the AddVariables method:

vars.AddVariables(
BoolVariable(
"warnings",
help="compilation with -Wall and similar",
default=True,
),
EnumVariable(
"debug",
help="debug output and symbols",
default="no",
allowed_values=("yes", "no", "full"),
map={},
ignorecase=0, # case-sensitive
),
ListVariable(
"shared",
help="libraries to build as shared libraries",
default="all",
names=list_of_libs,
),
PackageVariable(
"x11",
help="use X11 installed here (yes = search some places)",
default="yes",
),
PathVariable(
"qtdir",
help="where the root of Qt is installed",
default=qtdir
),
PathVariable(
"foopath",
help="where the foo library is installed",
default=foopath,
validator=PathVariable.PathIsDir,
),
)

Node Objects

SCons represents objects that are the sources or targets of build
operations as Nodes, which are internal data structures. There are a
number of user-visible types of nodes: File Nodes, Directory Nodes,
Value Nodes and Alias Nodes. Some of the node types have public
attributes and methods, described below. Each of the node types has a
global function and a matching environment method to create
instances: File, Dir, Value and Alias.

Filesystem Nodes

The File and Dir functions/methods return File Nodes and
Directory Nodes, respectively. Such Filesystem Nodes represent
build components that correspond to an entry in the computer's
filesystem, whether or not such an entry exists at the time the
Node is created. You do not usually need to explicitly create
filesystem Nodes, since when you supply a string as a target or
source of a Builder, SCons will create the Nodes as needed to
populate the dependency graph. Builders return the target Node(s)
in the form of a list, which you can then make use of. However,
since filesystem Nodes have some useful public attributes and
methods that you can use in SConscript files, it is sometimes
appropriate to create them manually, outside the regular context
of a Builder call.

The following attributes provide information about a Node:

node.path
The build path of the given file or directory. This path is
relative to the project top directory. The build path is the
same as the source path if variant_dir is not being used.

node.abspath
The absolute build path of the given file or directory.

node.relpath
The build path of the given file or directory relative to the
project top directory.

node.srcnode()
The srcnode method returns another File or Directory Node
representing the source path of the given File or Directory
Node.

Examples:

# Get the current build dir's path, relative to top.
Dir('.').path

# Current dir's absolute path
Dir('.').abspath

# Current dir's path relative to the project top directory
Dir('.').relpath

# Next line is always '.', because it is the top dir's path relative to itself.
Dir('#.').path

# Source path of the given source file.
File('foo.c').srcnode().path

# Builders return lists of File objects:
foo = env.Program('foo.c')
print("foo will be built in", foo[0].path)

Filesystem Node objects have methods to create new Filesystem
Nodes relative to the original Node. There are also times when
you may need to refer to an entry in a filesystem without knowing
in advance whether it's a file or a directory. For those
situations, there is an Entry method of filesystem node objects,
which returns a Node that can represent either a file or a
directory.

If the original Node is a Directory Node, these methods will
place the new Node within the directory the original Node
represents:

node.Dir(name)
Returns a directory Node name which is a subdirectory of the
directory represented by node.

node.File(name)
Returns a file Node name in the directory represented by
node.

node.Entry(name)
Returns an unresolved Node name in the directory represented
by node.

If the original Node is a File Node, these methods will place the
new Node in the same directory as the one the original Node
represents:

node.Dir(name)
Returns a Node name for a directory in the parent directory
of the file represented by node.

node.File(name)
Returns a Node name for a file in the parent directory of the
file represented by node.

node.Entry(name)
Returns an unresolved Node name in the parent directory of
the file represented by node.

For example:

# Get a Node for a file within a directory
incl = Dir('include')
f = incl.File('header.h')

# Get a Node for a subdirectory within a directory
dist = Dir('project-3.2.1')
src = dist.Dir('src')

# Get a Node for a file in the same directory
cfile = File('sample.c')
hfile = cfile.File('sample.h')

# Combined example
docs = Dir('docs')
html = docs.Dir('html')
index = html.File('index.html')
css = index.File('app.css')

Value and Alias Nodes

SCons provides two other Node types to represent object that will
not have an equivalent filesystem entry. Such Nodes always need
to be created explicitly.

The Alias method returns an Alias Node. Aliases are virtual
objects - they will not themselves result in physical objects
being constructed, but are entered into the dependency graph
related to their sources. An alias is checked for up to date by
checking if its sources are up-to-date. An alias is built by
making sure its sources have been built, and if any building took
place, applying any Actions that are defined as part of the
alias.

An Alias call creates an entry in the alias namespace, which is
used for disambiguation. If an alias source has a string valued
name, it will be resolved to a filesystem entry Node, unless it
is found in the alias namespace, in which case it is resolved to
the matching alias Node. As a result, the order of Alias calls is
significant. An alias can refer to another alias, but only if the
other alias has previously been created.

The Value method returns a Value Node. Value nodes are often used
for generated data that will not have any corresponding
filesystem entry, but will be used to determine whether a build
target is out-of-date, or to include as part of a build Action.
Common examples are timestamp strings, revision control version
strings and other run-time generated strings.

A Value Node can also be the target of a builder.

EXTENDING SCONS

SCons is designed to be extensible through provided facilities, so
changing the code of SCons itself is only rarely needed to customize
its behavior. A number of the main operations use callable objects
which can be supplemented by writing your own. Builders, Scanners and
Tools each use a kind of plugin system, allowing you to easily drop
in new ones. Information about creating Builder Objects and Scanner
Objects appear in the following sections. The instructions SCons
actually uses to construct things are called Actions, and it is easy
to create Action Objects and hand them to the objects that need to
know about those actions (besides Builders, see AddPostAction,
AddPreAction and Alias for some examples of other places that take
Actions). Action Objects are also described below. Adding new Tool
modules is described in Tool Modules

Builder Objects

scons can be extended to build different types of targets by adding
new Builder objects to a construction environment. In general, you
should only need to add a new Builder object when you want to build a
new type of file or other external target. For output file types
scons already knows about, you can usually modify the behavior of
premade Builders such as Program, Object or Library by changing the
construction variables they use ($CC, $LINK, etc.). In this manner
you can, for example, change the compiler to use, which is simpler
and less error-prone than writing a new builder. The documentation
for each Builder lists which construction variables it uses.

Builder objects are created using the Builder factory function. Once
created, a builder is added to an environment by entering it in the
$BUILDERS dictionary in that environment (some of the examples in
this section illustrate this). Doing so automatically triggers SCons
to add a method with the name of the builder to the environment.

The Builder function accepts the following keyword arguments:

action
The command used to build the target from the source. action may
be a string representing a template command line to execute, a
list of strings representing the command to execute with its
arguments (suitable for enclosing white space in an argument), a
dictionary mapping source file name suffixes to any combination
of command line strings (if the builder should accept multiple
source file extensions), a Python function, an Action object (see
Action Objects) or a list of any of the above.

An action function must accept three arguments: source, target
and env. source is a list of source nodes; target is a list of
target nodes; env is the construction environment to use for
context.

The action and generator arguments must not both be used for the
same Builder.

prefix
The prefix to prepend to the target file name. prefix may be a
string, a function (or other callable) that takes two arguments
(a construction environment and a list of sources) and returns a
prefix string, or a dictionary specifying a mapping from a
specific source suffix (of the first source specified) to a
corresponding target prefix string. For the dictionary form, both
the source suffix (key) and target prefix (value) specifications
may use environment variable substitution, and the target prefix
may also be a callable object. The default target prefix may be
indicated by a dictionary entry with a key of None.

b = Builder("build_it < $SOURCE > $TARGET", prefix="file-")

def gen_prefix(env, sources):
return "file-" + env['PLATFORM'] + '-'

b = Builder("build_it < $SOURCE > $TARGET", prefix=gen_prefix)

b = Builder(
"build_it < $SOURCE > $TARGET",
suffix={None: "file-", "$SRC_SFX_A": gen_prefix},
)

suffix
The suffix to append to the target file name. Specified in the
same manner as for prefix above. If the suffix is a string, then
scons prepends a '.' to the suffix if it's not already there. The
string returned by the callable object or obtained from the
dictionary is untouched, and you need to manually prepend a '.'
if one is required.

b = Builder("build_it < $SOURCE > $TARGET", suffix="-file")

def gen_suffix(env, sources):
return "." + env['PLATFORM'] + "-file"

b = Builder("build_it < $SOURCE > $TARGET", suffix=gen_suffix)
b = Builder(
"build_it < $SOURCE > $TARGET",
suffix={None: ".sfx1", "$SRC_SFX_A": gen_suffix},
)

ensure_suffix
If set to a true value, ensures that targets will end in suffix.
Thus, the suffix will also be added to any target strings that
have a suffix that is not already suffix. The default behavior
(also indicated by a false value) is to leave unchanged any
target string that looks like it already has a suffix.

b1 = Builder("build_it < $SOURCE > $TARGET", suffix=".out")
b2 = Builder(
"build_it < $SOURCE > $TARGET", suffix=".out", ensure_suffix=True
)
env = Environment()
env['BUILDERS']['B1'] = b1
env['BUILDERS']['B2'] = b2

# Builds "foo.txt" because ensure_suffix is not set.
env.B1('foo.txt', 'foo.in')

# Builds "bar.txt.out" because ensure_suffix is set.
env.B2('bar.txt', 'bar.in')

src_suffix
The expected source file name suffix. src_suffix may be a string
or a list of strings.

target_scanner
A Scanner object that will be invoked to find implicit
dependencies for this target file. Use only to specify Scanner
objects that find implicit dependencies based on the target file
and construction environment, not for implicit dependencies based
on source files (use source_scanner for those). See the section
called "Scanner Objects" for information about creating your own
Scanner objects.

source_scanner
A Scanner object that will be invoked to find implicit
dependencies in any source files used to build this target file.
Use to specify a scanner to find things like #include lines in
source files. The pre-built DirScanner Scanner object may be used
to indicate that this Builder should scan directory trees for
on-disk changes to files that scons does not know about from
other Builder or function calls. See the section called "Scanner
Objects" for information about creating your own Scanner objects.

target_factory
A factory function that the Builder will use to turn any targets
specified as strings into SCons Nodes. By default, SCons assumes
that all targets are files (that is, the default factory is
File). Other useful target_factory values include Dir for when a
Builder creates a directory target, and Entry for when a Builder
can create either a file or directory target.

Example:

def my_mkdir(target, source, env):
# target[0] will be a Dir node for 'new_directory'

MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
env = Environment()
env.Append(BUILDERS={'MakeDirectory': MakeDirectoryBuilder})
env.MakeDirectory('new_directory', [])

Note that the call to the MakeDirectory Builder needs to specify
an empty source list to make the filename string represent the
builder's target. SCons assumes a single positional argument to
a builder is the source, and would try to deduce the target name
from it, which, in the absence of an automatically-added prefix
or suffix, would lead to a matching target and source name and a
circular dependency.

source_factory
A factory function that the Builder will use to turn any sources
specified as strings into SCons Nodes. By default, SCons assumes
that all source are files (that is, the default factory is File).
Other useful source_factory values include Dir for when a Builder
uses a directory as a source, and Entry for when a Builder can
use files or directories (or both) as sources.

Example:

def collect(target, source, env):
# target[0] will default to a File node for 'archive' (no target_factory)
# source[0] will be a Dir node for 'directory_name'

CollectBuilder = Builder(action=collect, source_factory=Dir)
env = Environment()
env.Append(BUILDERS={'Collect': CollectBuilder})
env.Collect('archive', 'directory_name')

emitter
A function or list of functions to manipulate the target and
source lists before dependencies are established and the
target(s) are actually built. emitter can also be a string
containing a construction variable to expand to an emitter
function or list of functions, or a dictionary mapping source
file suffixes to emitter functions. (Only the suffix of the first
source file is used to select the actual emitter function from an
emitter dictionary.)

A function passed as emitter must accept three arguments: source,
target and env. source is a list of source nodes, target is a
list of target nodes, env is the construction environment to use
for context.

An emitter must return a tuple containing two lists, the list of
targets to be built by this builder, and the list of sources for
this builder.

Example:

def e(target, source, env):
return target + ['foo.foo'], source + ['foo.src']

# Simple association of an emitter function with a Builder.
b = Builder("my_build < $TARGET > $SOURCE", emitter=e)

def e2(target, source, env):
return target + ['bar.foo'], source + ['bar.src']

# Simple association of a list of emitter functions with a Builder.
b = Builder("my_build < $TARGET > $SOURCE", emitter=[e, e2])

# Calling an emitter function through a construction variable.
env = Environment(MY_EMITTER=e)
b = Builder("my_build < $TARGET > $SOURCE", emitter='$MY_EMITTER')

# Calling a list of emitter functions through a construction variable.
env = Environment(EMITTER_LIST=[e, e2])
b = Builder("my_build < $TARGET > $SOURCE", emitter='$EMITTER_LIST')

# Associating multiple emitters with different file
# suffixes using a dictionary.
def e_suf1(target, source, env):
return target + ['another_target_file'], source

def e_suf2(target, source, env):
return target, source + ['another_source_file']

b = Builder(
action="my_build < $TARGET > $SOURCE",
emitter={'.suf1': e_suf1, '.suf2': e_suf2}
)

multi
Specifies whether this builder is allowed to be called multiple
times for the same target file(s). The default is False, which
means the builder can not be called multiple times for the same
target file(s). Calling a builder multiple times for the same
target simply adds additional source files to the target; it is
not allowed to change the environment associated with the target,
specify additional environment overrides, or associate a
different builder with the target.

env
A construction environment that can be used to fetch source code
using this Builder. (Note that this environment is not used for
normal builds of normal target files, which use the environment
that was used to call the Builder for the target file.)

generator
A function that returns a list of actions that will be executed
to build the target(s) from the source(s). The returned action(s)
may be an Action object, or anything that can be converted into
an Action object (see the next section).

A function passed as generator must accept four arguments:
source, target, env and for_signature. source is a list of
source nodes, target is a list of target nodes, env is the
construction environment to use for context, and for_signature is
a Boolean value that tells the function if it is being called for
the purpose of generating a build signature (as opposed to
actually executing the command). Since the build signature is
used for rebuild determination, the function should omit those
elements that do not affect whether a rebuild should be triggered
if for_signature is true.

Example:

def g(source, target, env, for_signature):
return [["gcc", "-c", "-o"] + target + source]

b = Builder(generator=g)

The generator and action arguments must not both be used for the
same Builder.

src_builder
Specifies a builder to use when a source file name suffix does
not match any of the suffixes of the builder. Using this argument
produces a multi-stage builder.

single_source
Specifies that this builder expects exactly one source file per
call. Giving more than one source file without target files
results in implicitly calling the builder multiple times (once
for each source given). Giving multiple source files together
with target files results in a UserError exception.

source_ext_match
When the specified action argument is a dictionary, the default
behavior when a builder is passed multiple source files is to
make sure that the extensions of all the source files match. If
it is legal for this builder to be called with a list of source
files with different extensions, this check can be suppressed by
setting source_ext_match to False or some other non-true value.
In this case, scons will use the suffix of the first specified
source file to select the appropriate action from the action
dictionary.

In the following example, the setting of source_ext_match
prevents scons from exiting with an error due to the mismatched
suffixes of foo.in and foo.extra.

b = Builder(action={'.in': 'build $SOURCES > $TARGET'}, source_ext_match=False)
env = Environment(BUILDERS={'MyBuild': b})
env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

env
A construction environment that can be used to fetch source code
using this Builder. (Note that this environment is not used for
normal builds of normal target files, which use the environment
that was used to call the Builder for the target file.)

b = Builder(action="build < $SOURCE > $TARGET")
env = Environment(BUILDERS={'MyBuild' : b})
env.MyBuild('foo.out', 'foo.in', my_arg='xyzzy')

chdir
A directory from which scons will execute the action(s) specified
for this Builder. If the chdir argument is a string or a
directory Node, scons will change to the specified directory. If
the chdir is not a string or Node and is non-zero, then scons
will change to the target file's directory.

Note that scons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the
chdir keyword argument--that is, the expanded file names will
still be relative to the project top directory, and consequently
incorrect relative to the chdir directory. Builders created using
chdir keyword argument, will need to use construction variable
expansions like ${TARGET.file} and ${SOURCE.file} to use just the
filename portion of the targets and source.

b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}", chdir=True)
env = Environment(BUILDERS={'MyBuild' : b})
env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

Warning

Python only keeps one current directory location even if
there are multiple threads. This means that use of the chdir
argument will not work with the SCons -j option, because
individual worker threads spawned by SCons interfere with
each other when they start changing directory.

Any additional keyword arguments supplied when a Builder object is
created (that is, when the Builder function is called) will be set in
the executing construction environment when the Builder object is
called. The canonical example here would be to set a construction
variable to the repository of a source code system.

Any such keyword arguments supplied when a Builder object is called
will only be associated with the target created by that particular
Builder call (and any other files built as a result of the call).
These extra keyword arguments are passed to the following functions:
command generator functions, function Actions, and emitter functions.

Action Objects

The Builder factory function will turn its action keyword argument
into an appropriate internal Action object, as will the Command
function. You can also explicitly create Action objects for passing
to Builder, or other functions that take actions as arguments, by
calling the Action factory function. This may more efficient when
multiple Builder objects need to do the same thing rather than
letting each of those Builder objects create a separate Action
object. It also allows more flexible configuration of an Action
object. For example, to control the message printed when the action
is taken you need to create the action object using Action.

The Action factory function returns an appropriate object for the
action represented by the type of the action argument (the first
positional parameter):

+o If action is already an Action object, the object is simply
returned.

+o If action is a string, a command-line Action is returned. If such
a string begins with @, the command line is not printed. If the
string begins with hyphen (-), the exit status from the specified
command is ignored, allowing execution to continue even if the
command reports failure:

Action('$CC -c -o $TARGET $SOURCES')

# Doesn't print the line being executed.
Action('@build $TARGET $SOURCES')

# Ignores return value
Action('-build $TARGET $SOURCES')

+o If action is a list, then a list of Action objects is returned.
An Action object is created as necessary for each element in the
list. If an element within the list is itself a list, the
embedded list is taken as the command and arguments to be
executed via the command line. This allows white space to be
enclosed in an argument rather than taken as a separator by
defining a command in a list within a list:

Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

+o If action is a callable object, a Function Action is returned.
The callable must accept three keyword arguments: target, source
and env. target is a Node object representing the target file,
source is a Node object representing the source file and env is
the construction environment used for building the target file.

The target and source arguments may be lists of Node objects if
there is more than one target file or source file. The actual
target and source file name(s) may be retrieved from their Node
objects via the built-in Python str function:

target_file_name = str(target)
source_file_names = [str(x) for x in source]

The function should return 0 or None to indicate a successful
build of the target file(s). The function may raise an exception
or return a non-zero exit status to indicate an unsuccessful
build.

def build_it(target=None, source=None, env=None):
# build the target from the source
return 0

a = Action(build_it)

+o If action is not one of the above types, no action object is
generated and Action returns None.

The environment method form env.Action will expand construction
variables in any argument strings, including action, at the time it
is called, using the construction variables in the construction
environment through which it was called. The global function form
Action delays variable expansion until the Action object is actually
used.

The optional second argument to Action is used to control the output
which is printed when the Action is actually performed. If this
parameter is omitted, or if the value is an empty string, a default
output depending on the type of the action is used. For example, a
command-line action will print the executed command. The following
argument types are accepted:

+o If the second argument is a string, or if the cmdstr keyword
argument is supplied, the string defines what is printed.
Substitution is performed on the string before it is printed. The
string typically contains substitutable variables, notably
$TARGET(S) and $SOURCE(S), or consists of just a single variable
which is optionally defined somewhere else. SCons itself heavily
uses the latter variant.

+o If the second argument is a function, or if the strfunction
keyword argument is supplied, the function will be called to
obtain the string to be printed when the action is performed. The
function must accept three keyword arguments: target, source and
env, with the same interpretation as for a callable action
argument above. The function is responsible for handling any
required substitutions.

+o If the second argument is None, or if cmdstr=None is supplied,
output is suppressed entirely.

The cmdstr and strfunction keyword arguments may not both be supplied
in a single call to Action

Printing of action strings is affected by the setting of
$PRINT_CMD_LINE_FUNC.

Examples:

def build_it(target, source, env):
# build the target from the source
return 0

def string_it(target, source, env):
return "building '%s' from '%s'" % (target[0], source[0])

# Use a positional argument.
f = Action(build_it, string_it)
s = Action(build_it, "building '$TARGET' from '$SOURCE'")

# Alternatively, use a keyword argument.
f = Action(build_it, strfunction=string_it)
s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")

# You can provide a configurable variable.
l = Action(build_it, '$STRINGIT')

Any additional positional arguments, if present, may either be
construction variables or lists of construction variables whose
values will be included in the signature of the Action (the build
signature) when deciding whether a target should be rebuilt because
the action changed. Such variables may also be specified using the
varlist keyword parameter; both positional and keyword forms may be
present, and will be combined. This is necessary whenever you want a
target to be rebuilt when a specific construction variable changes.
This is not often needed for a string action, as the expanded
variables will normally be part of the command line, but may be
needed if a Python function action uses the value of a construction
variable when generating the command line.

def build_it(target, source, env):
# build the target from the 'XXX' construction variable
with open(target[0], 'w') as f:
f.write(env['XXX'])
return 0

# Use positional arguments.
a = Action(build_it, '$STRINGIT', ['XXX'])

# Alternatively, use a keyword argument.
a = Action(build_it, varlist=['XXX'])

The Action factory function can be passed the following optional
keyword arguments to modify the Action object's behavior:

chdir
If chdir is true (the default is False), SCons will change
directories before executing the action. If the value of chdir is
a string or a directory Node, SCons will change to the specified
directory. Otherwise, if chdir evaluates true, SCons will change
to the target file's directory.

Note that SCons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the
chdir parameter - that is, the expanded file names will still be
relative to the project top directory, and consequently incorrect
relative to the chdir directory. Builders created using chdir
keyword argument, will need to use construction variable
expansions like ${TARGET.file} and ${SOURCE.file} to use just the
filename portion of the targets and source. Example:

a = Action("build < ${SOURCE.file} > ${TARGET.file}", chdir=True)

exitstatfunc
If provided, must be a callable which accepts a single parameter,
the exit status (or return value) from the specified action, and
which returns an arbitrary or modified value. This can be used,
for example, to specify that an Action object's return value
should be ignored under special conditions and SCons should,
therefore, consider that the action always succeeds. Example:

def always_succeed(s):
# Always return 0, which indicates success.
return 0

a = Action("build < ${SOURCE.file} > ${TARGET.file}", exitstatfunc=always_succeed)

batch_key
If provided, indicates that the Action can create multiple target
files by processing multiple independent source files
simultaneously. (The canonical example is "batch compilation" of
multiple object files by passing multiple source files to a
single invocation of a compiler such as Microsoft Visual C++. If
the batch_key argument evaluates True and is not a callable
object, the configured Action object will cause scons to collect
all targets built with the Action object and configured with the
same construction environment into single invocations of the
Action object's command line or function. Command lines will
typically want to use the $CHANGED_SOURCES construction variable
(and possibly $CHANGED_TARGETS as well) to only pass to the
command line those sources that have actually changed since their
targets were built. Example:

a = Action('build $CHANGED_SOURCES', batch_key=True)

The batch_key argument may also be a callable function that
returns a key that will be used to identify different "batches"
of target files to be collected for batch building. A batch_key
function must accept four parameters: action, env, target and
source. The first parameter, action, is the active action object.
The second parameter, env, is the construction environment
configured for the target. The target and source parameters are
the lists of targets and sources for the configured action.

The returned key should typically be a tuple of values derived
from the arguments, using any appropriate logic to decide how
multiple invocations should be batched. For example, a batch_key
function may decide to return the value of a specific
construction variable from env which will cause scons to
batch-build targets with matching values of that construction
variable, or perhaps return the Python id() of the entire
construction environment, in which case scons will batch-build
all targets configured with the same construction environment.
Returning None indicates that the particular target should not be
part of any batched build, but instead will be built by a
separate invocation of action's command or function. Example:

def batch_key(action, env, target, source):
tdir = target[0].dir
if tdir.name == 'special':
# Don't batch-build any target
# in the special/ subdirectory.
return None
return (id(action), id(env), tdir)
a = Action('build $CHANGED_SOURCES', batch_key=batch_key)

Miscellaneous Action Functions

SCons supplies Action functions that arrange for various common
file and directory manipulations to be performed. These are
similar in concept to "tasks" in the Ant build tool, although the
implementation is slightly different. These functions do not
actually perform the specified action at the time the function is
called, but rather are factory functions which return an Action
object that can be executed at the appropriate time.

There are two natural ways that these Action Functions are
intended to be used.

First, if you need to perform the action at the time the
SConscript file is being read, you can use the Execute global
function:

Execute(Touch('file'))

Second, you can use these functions to supply Actions in a list
for use by the env.Command method. This can allow you to perform
more complicated sequences of file manipulation without relying
on platform-specific external commands:

env = Environment(TMPBUILD='/tmp/builddir')
env.Command(
target='foo.out',
source='foo.in',
action=[
Mkdir('$TMPBUILD'),
Copy('$TMPBUILD', '${SOURCE.dir}'),
"cd $TMPBUILD && make",
Delete('$TMPBUILD'),
],
)

Chmod(dest, mode)
Returns an Action object that changes the permissions on the
specified dest file or directory to the specified mode which
can be octal or string, similar to the POSIX chmod command.
Examples:

Execute(Chmod('file', 0o755))

env.Command(
'foo.out',
'foo.in',
[Copy('$TARGET', '$SOURCE'), Chmod('$TARGET', 0o755)],
)

Execute(Chmod('file', "ugo+w"))

env.Command(
'foo.out',
'foo.in',
[Copy('$TARGET', '$SOURCE'), Chmod('$TARGET', "ugo+w")],
)

The behavior of Chmod is limited on Windows and on
WebAssembly platforms, see the notes in the Python
documentation for os.chmod[9], which is the underlying
function.

Copy(dest, src)
Returns an Action object that will copy the src source file
or directory to the dest destination file or directory. If
src is a list, dest must be a directory if it already exists.
Examples:

Execute(Copy('foo.output', 'foo.input'))

env.Command('bar.out', 'bar.in', Copy('$TARGET', '$SOURCE'))

Delete(entry, [must_exist])
Returns an Action that deletes the specified entry, which may
be a file or a directory tree. If a directory is specified,
the entire directory tree will be removed. If the must_exist
flag is set to a true value, then a Python error will be
raised if the specified entry does not exist; the default is
false, that is, the Action will silently do nothing if the
entry does not exist. Examples:

Execute(Delete('/tmp/buildroot'))

env.Command(
'foo.out',
'foo.in',
action=[
Delete('${TARGET.dir}'),
MyBuildAction,
],
)

Execute(Delete('file_that_must_exist', must_exist=True))

Mkdir(name)
Returns an Action that creates the directory name and all
needed intermediate directories. name may also be a list of
directories to create. Examples:

Execute(Mkdir('/tmp/outputdir'))

env.Command(
'foo.out',
'foo.in',
action=[
Mkdir('/tmp/builddir'),
Copy('/tmp/builddir/foo.in', '$SOURCE'),
"cd /tmp/builddir && make",
Copy('$TARGET', '/tmp/builddir/foo.out'),
],
)

Move(dest, src)
Returns an Action that moves the specified src file or
directory to the specified dest file or directory. Examples:

Execute(Move('file.destination', 'file.source'))

env.Command(
'output_file',
'input_file',
action=[MyBuildAction, Move('$TARGET', 'file_created_by_MyBuildAction')],
)

Touch(file)
Returns an Action that updates the modification time on the
specified file. Examples:

Execute(Touch('file_to_be_touched'))

env.Command('marker', 'input_file', action=[MyBuildAction, Touch('$TARGET')])

Variable Substitution

Before executing a command, scons performs parameter expansion
(substitution) on the string that makes up the action part of the
builder. The format of a substitutable parameter is
${expression}. If expression refers to a variable, the braces in
${expression} can be omitted unless the variable name is
immediately followed by a character that could either be
interpreted as part of the name, or is Python syntax such as [
(for indexing/slicing) or . (for attribute access - see Special
Attributes below).

If expression refers to a construction variable, it (including
the $ or ${ }) is replaced with the value of that variable in the
construction environment at the time of execution. If expression
looks like a variable name but is not defined in the construction
environment it is replaced with an empty string. If expression
refers to one of the Special Variables (see below) the
corresponding value of the variable is substituted. expression
may also be a Python expression to be evaluated. See Python Code
Substitution below for a description.

SCons uses the following rules when converting construction
variables into command line strings:

+o If the value is a string it is interpreted as space delimited
command line arguments.

+o If the value is a list it is interpreted as a list of command
line arguments. Each element of the list is converted to a
string.

+o Anything that is not a list or string is converted to a
string and interpreted as a single command line argument.

+o Newline characters (\n) delimit lines. The newline parsing is
done after all other parsing, so it is not possible for
arguments (e.g. file names) to contain embedded newline
characters.

+o For a literal $ use $$. For example, $$FOO will be left in
the final string as $FOO.

When a build action is executed, a hash of the command line is
saved, together with other information about the target(s) built
by the action, for future use in rebuild determination. This is
called the build signature (or build action signature). The
escape sequence $( subexpression $) may be used to indicate parts
of a command line that may change without causing a rebuild--that
is, which are not to be included when calculating the build
signature. All text from $( up to and including the matching $)
will be removed from the command line before it is added to the
build signature while only the $( and $) will be removed before
the command is executed. For example, the command line string:

"echo Last build occurred $( $TODAY $). > $TARGET"

would execute the command:

echo Last build occurred $TODAY. > $TARGET

but the build signature added to any target files would be
computed from:

echo Last build occurred . > $TARGET

While construction variables are normally directly substituted,
if a construction variable has a value which is a callable Python
object (a function, or a class with a __call__ method), that
object is called during substitution. The callable must accept
four arguments: target, source, env and for_signature. source is
a list of source nodes, target is a list of target nodes, env is
the construction environment to use for context, and
for_signature is a boolean value that tells the callable if it is
being called for the purpose of generating a build signature.
Since the build signature is used for rebuild determination,
variable elements that do not affect whether a rebuild should be
triggered should be omitted from the returned string if
for_signature is true. See $( and $) above for the syntax.

SCons will insert whatever the callable returns into the expanded
string:

def foo(target, source, env, for_signature):
return "bar"

# Will expand $BAR to "bar baz"
env = Environment(FOO=foo, BAR="$FOO baz")

As a reminder, substitution happens when $BAR is actually used in
a builder action. The value of env['BAR'] will be exactly as it
was set: "$FOO baz". This can make debugging tricky, as the
substituted result is not available at the time the SConscript
files are being interpreted and thus not available to the print
function. However, you can perform the substitution on demand by
calling the env.subst method for this purpose.

You can use this feature to pass arguments to a callable variable
by creating a callable class that stores passed arguments in the
instance, and then uses them (in the __call__ method) when the
instance is called. Note that in this case, the entire variable
expansion must be enclosed by curly braces so that the arguments
will be associated with the instantiation of the class:

class foo:
def __init__(self, arg):
self.arg = arg

def __call__(self, target, source, env, for_signature):
return self.arg + " bar"

# Will expand $BAR to "my argument bar baz"
env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

Substitution: Special Variables

Besides regular construction variables, scons provides the
following Special Variables for use in expanding commands:

$CHANGED_SOURCES
The file names of all sources of the build command that have
changed since the target was last built.

$CHANGED_TARGETS
The file names of all targets that would be built from
sources that have changed since the target was last built.

$SOURCE
The file name of the source of the build command, or the file
name of the first source if multiple sources are being built.

$SOURCES
The file names of the sources of the build command.

$TARGET
The file name of the target being built, or the file name of
the first target if multiple targets are being built.

$TARGETS
The file names of all targets being built.

$UNCHANGED_SOURCES
The file names of all sources of the build command that have
not changed since the target was last built.

$UNCHANGED_TARGETS
The file names of all targets that would be built from
sources that have not changed since the target was last
built.

These names are reserved and may not be assigned to or used as
construction variables. SCons computes them in a
context-dependent manner and they are not retrieved from a
construction environment.

For example, the following builder call:

env = Environment(CC='cc')
env.Command(
target=['foo'],
source=['foo.c', 'bar.c'],
action='@echo $CC -c -o $TARGET $SOURCES'
)

would produce the following output:

cc -c -o foo foo.c bar.c

In the previous example, a string ${SOURCES[1]} would expand to:
bar.c.

Substitution: Special Attributes

A variable name may have the following modifiers appended within
the enclosing curly braces to access properties of the
interpolated string. These are known as special attributes.
base -
The base path of the file name,
including the directory path
but excluding any suffix.

dir - The name of the directory in which the file exists.
file - The file name, minus any directory portion.
filebase - Like file but minus its suffix.
suffix - Just the file suffix.
abspath - The absolute path name of the file.
relpath - The path name of the file relative to the project
top directory.
posix -
The path with directories separated by forward slashes
(/).
Sometimes necessary on Windows systems
when a path references a file on other (POSIX) systems.

windows -
The path with directories separated by backslashes
(\\).
Sometimes necessary on POSIX-style systems
when a path references a file on other (Windows) systems.
win32 is a (deprecated) synonym for
windows.

srcpath -
The directory and file name to the source file linked to
this file through
VariantDir().
If this file isn't linked,
it just returns the directory and filename unchanged.

srcdir -
The directory containing the source file linked to this
file through
VariantDir().
If this file isn't linked,
it just returns the directory part of the filename.

rsrcpath -
The directory and file name to the source file linked to
this file through
VariantDir().
If the file does not exist locally but exists in a
Repository,
the path in the Repository is returned.
If this file isn't linked, it just returns the
directory and filename unchanged.

rsrcdir -
The Repository directory containing the source file
linked to this file through
VariantDir().
If this file isn't linked,
it just returns the directory part of the filename.


For example, the specified target will expand as follows for the
corresponding modifiers:

$TARGET => sub/dir/file.x
${TARGET.base} => sub/dir/file
${TARGET.dir} => sub/dir
${TARGET.file} => file.x
${TARGET.filebase} => file
${TARGET.suffix} => .x
${TARGET.abspath} => /top/dir/sub/dir/file.x
${TARGET.relpath} => sub/dir/file.x

$TARGET => ../dir2/file.x
${TARGET.abspath} => /top/dir2/file.x
${TARGET.relpath} => ../dir2/file.x

SConscript('src/SConscript', variant_dir='sub/dir')
$SOURCE => sub/dir/file.x
${SOURCE.srcpath} => src/file.x
${SOURCE.srcdir} => src

Repository('/usr/repository')
$SOURCE => sub/dir/file.x
${SOURCE.rsrcpath} => /usr/repository/src/file.x
${SOURCE.rsrcdir} => /usr/repository/src

Some modifiers can be combined, like ${TARGET.srcpath.base),
${TARGET.file.suffix}, etc.

Python Code Substitution

If a substitutable expression using the notation ${expression}
does not appear to match one of the other substitution patterns,
it is evaluated as a Python expression. This uses Python's eval
function, with the globals parameter set to the current
environment's set of construction variables, and the result
substituted in. So in the following case:

env.Command(
'foo.out', 'foo.in', "echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET"
)

the command executed will be either

echo FOO > foo.out

or

echo BAR > foo.out

according to the current value of env['COND'] when the command is
executed. The evaluation takes place when the target is being
built, not when the SConscript is being read. So if env['COND']
is changed later in the SConscript, the final value will be used.

Here's a more complete example. Note that all of COND, FOO, and
BAR are construction variables, and their values are substituted
into the final command. FOO is a list, so its elements are
interpolated separated by spaces.

env=Environment()
env['COND'] = 1
env['FOO'] = ['foo1', 'foo2']
env['BAR'] = 'barbar'
env.Command(
'foo.out', 'foo.in', "echo ${COND==1 and FOO or BAR} > $TARGET"
)

will execute:

echo foo1 foo2 > foo.out

In point of fact, Python expression evaluation is how the special
attributes are substituted: they are simply attributes of the
Python objects that represent $TARGET, $SOURCES, etc., which
SCons passes to eval which returns the value.

Caution

Use of the Python eval function is considered to have
security implications, since, depending on input sources,
arbitrary unchecked strings of code can be executed by the
Python interpreter. Although SCons makes use of it in a
somewhat restricted context, you should be aware of this
issue when using the ${python-expression-for-subst} form.

Scanner Objects

Scanner objects are used to scan specific file types for implicit
dependencies, for example embedded preprocessor/compiler directives
that cause other files to be included during processing. SCons has a
number of pre-built Scanner objects, so it is usually only necessary
to set up Scanners for new file types. You do this by calling the
Scanner factory function. Scanner accepts the following arguments.
Only function is required; the rest are optional:

function
A function which can process ("scan") a given Node (usually a
file) and return a list of Nodes representing any implicit
dependencies (usually files) which will be tracked for the Node.
The function must accept three required arguments, node, env and
path, and an optional fourth, arg. node is the internal SCons
node representing the file to scan, env is the construction
environment to use during the scan, and path is a tuple of
directories that can be searched for files, as generated by the
optional scanner path_function. If the argument parameter was
supplied when the Scanner object was created, it is passed as the
arg parameter to the scanner function when it is called. Since
argument is optional, the scanner function may be called without
an arg parameter.

The scanner function can make use of str(node) to fetch the name
of the file, node.dir to fetch the directory the file is in,
node.get_contents() to fetch the contents of the file as bytes or
node.get_text_contents() to fetch the contents of the file as
text.

The scanner function should account for any directories listed in
the path parameter when determining the existence of possible
dependencies. External tools such as the C/C++ preprocessor are
given lists of directories to search for source file inclusion
directives (e.g. #include "myheader.h"). That list is generated
from the relevant path variable (e.g. $CPPPATH for C/C++). The
Scanner can be directed to pass the same list on to the scanner
function via the path parameter so it can search in the same
places. The Scanner is enabled to pass this list via the
path_function argument at Scanner creation time.

Instead of a scanner function, you can supply a dictionary as the
function parameter. The dictionary must map keys (such as file
suffixes) to other Scanner objects. A Scanner created this way
serves as a dispatcher: the Scanner's skeys parameter is
automatically populated with the dictionary's keys, indicating
that the Scanner handles Nodes which would be selected by those
keys; the mapping is then used to pass the file on to a different
Scanner that would not have been selected to handle that Node
based on its own skeys.

Note that the file to scan is not guaranteed to exist at the time
the scanner is called - it could be a generated file which has
not been generated yet - so the scanner function must be tolerant
of that.

While many scanner functions operate on source code files by
looking for known patterns in the code, they can really do
anything they need to. For example, the Program Builder is
assigned a target_scanner which examines the list of libraries
supplied for the build ($LIBS) and decides whether to add them as
dependencies, it does not look inside the built binary.

It is up to the scanner function to decide whether or not to
generate an SCons dependency for candidates identified by
scanning. Dependencies are a key part of SCons operation,
enabling both rebuild determination and correct ordering of
builds. It is particularly important that generated files which
are dependencies are added into the Node graph, or
use-before-create failures are likely. However, not everything
may need to be tracked as a dependency. In some cases,
implementation-provided header files change infrequently but are
included very widely, so tracking them in the SCons node graph
could become quite expensive for limited benefit - consider for
example the C standard header file string.h. The scanner function
is not passed any special information to help make this choice,
so the decision-making encoded in the scanner function must be
carefully considered.

name
The name to use for the Scanner. This is mainly used to identify
the Scanner internally. The default value is "NONE".

argument
If specified, will be passed to the scanner function function and
the path function path_function when called, as the optional
parameter each of those functions takes.

skeys
Scanner key(s) indicating the file types this scanner is
associated with. Used internally to select an appropriate
scanner. In the usual case of scanning for file names, this
argument will be a list of suffixes for the different file types
that this Scanner knows how to scan. If skeys is a string, it
will be expanded into a list by the current environment.

path_function
If specified, a function to generate paths to pass to the scanner
function to search while generating dependencies. The function
must take five arguments: a construction environment, a Node for
the directory containing the SConscript file in which the first
target was defined, a list of target nodes, a list of source
nodes, and the value of argument if it was supplied when the
Scanner was created (since argument is optional, the function may
be called without this argument, the path_function should be
prepared for this). Must return a tuple of directories that can
be searched for files to be returned by this Scanner object.

The FindPathDirs function can be called to return a ready-made
path_function for a given construction variable name, which is
often easier than writing your own function from scratch. For
example, path_function=FindPathDirs('CPPPATH') means the scanner
function will be called with the paths extracted from $CPPPATH in
the construction environment env, and passed as the path
parameter to the scanner function.

node_class
The class of Node that should be returned by this Scanner object.
Any strings or other objects returned by the scanner function
that are not of this class will be run through the function
supplied by the node_factory argument. A value of None can be
supplied to indicate no conversion; the default is to return File
nodes.

node_factory
A Python function that will take a string or other object and
turn it into the appropriate class of Node to be returned by this
Scanner object, as indicated by node_class.

scan_check
A Python function that takes two arguments, a Node (file) and a
construction environment, and returns whether the Node should, in
fact, be scanned for dependencies. This check can be used to
eliminate unnecessary calls to the scanner function when, for
example, the underlying file represented by a Node does not yet
exist.

recursive
Specifies whether this scanner should be re-invoked on the
dependency files returned by the scanner. If omitted, the Node
subsystem will only invoke the scanner on the file being scanned
and not recurse. Recursion is needed when the files returned by
the scanner may themselves contain further file dependencies, as
in the case of preprocessor #include lines. A value that
evaluates true enables recursion; recursive may be a callable
function, in which case it will be called with a list of Nodes
found and should return a list of Nodes that should be scanned
recursively; this can be used to select a specific subset of
Nodes for additional scanning.

Once created, a Scanner can be added to an environment by setting it
in the $SCANNERS list, which automatically triggers SCons to also add
it to the environment as a method. However, usually a scanner is not
truly standalone, but needs to be plugged in to the existing
selection mechanism for deciding how to scan source files based on
filename extensions. For this, SCons has a global SourceFileScanner
object that is used by the Object, SharedObject and StaticObject
builders to decide which scanner should be used. You can use the
SourceFileScanner.add_scanner() method to add your own Scanner object
to the SCons infrastructure that builds target programs or libraries
from a list of source files of different types:

def xyz_scan(node, env, path):
contents = node.get_text_contents()
# Scan the contents and return the included files.

XYZScanner = Scanner(xyz_scan)

SourceFileScanner.add_scanner('.xyz', XYZScanner)

env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

Tool Modules

Custom tools can be added to a project either by placing them in the
site_tools subdirectory of a configured site directory, or in a
location specified by the toolpath keyword argument to Environment.
You have to arrange to call a tool to put it into effect, either as
part of the list given to the tools keyword argument at construction
environment initialization, or by calling env.Tool.

The toolpath parameter takes a list of path strings, and the tools
parameter takes a list of tools, which are often strings:

env = Environment(tools=['default', 'foo'], toolpath=['tools'])

This looks for a tool specification module foo in directory tools and
in the standard locations, as well as using the ordinary default
tools for the platform.

When looking up tool specification modules, directories specified via
toolpath are considered before the existing tool path (site_tools
subdirectories of the default or specified site directories), which
are in turn considered before built-in tools. For example, adding a
tool specification module gcc.py to the toolpath directory would
override the built-in gcc tool. The toolpath is saved in the
environment and will be used by subsequent calls to the env.Tool
method, as well as by env.Clone.

base = Environment(toolpath=['custom_path'])
derived = base.Clone(tools=['custom_tool'])
derived.CustomBuilder()

A tool specification module is a form of Python module, looked up
internally using the Python import mechanism, so a tool can consist
either of a single Python file taking the name of the tool (e.g.
mytool.py) or a directory taking the name of the tool (e.g. mytool/)
which contains at least an __init__.py file. A tool specification
module has two required entry points:

generate(env, **kwargs)
Modify the construction environment env to set up necessary
construction variables, Builders, Emitters, etc., so the
facilities represented by the tool can be executed. Take care not
to overwrite construction variables which may have been
explicitly set by the user; retain and/or append instead. For
example:

def generate(env):
...
if 'MYTOOL' not in env:
env['MYTOOL'] = env.Detect("mytool")
flags = env.get('MYTOOLFLAGS', SCons.Util.CLVar())
env.AppendUnique(MYTOOLFLAGS='--myarg')
...

The generate function may use any keyword arguments that the user
supplies via kwargs to vary its initialization.

exists(env)
Return a truthy value if the tool can be called in the context of
env, else return a falsy value. Usually this means looking up one
or more known programs using the PATH from the supplied env, but
the tool can make the exists decision in any way it chooses.

Note

At the moment, user-added tools do not automatically have their
exists function called. As a result, it is recommended that the
generate function be defensively coded - that is, do not rely on
any necessary existence checks already having been performed.
This is expected to be a temporary limitation, and the exists
function should still be provided.

An element of the tools list may also be a function or other callable
object (including a Tool object returned by a previous call to Tool)
in which case the Environment function will directly call that object
to update the new construction environment. No tool lookup is done in
this case.

def my_tool(env):
env['XYZZY'] = 'xyzzy'

env = Environment(tools=[my_tool])

An element of the tools list may also be a two-element list or tuple
of the form (toolname, kw_dict). SCons searches for the tool
specification module toolname as described above, and passes kw_dict,
which must be a dictionary, as keyword arguments to the tool's
generate function. The generate function can use those arguments to
modify the tool's behavior by setting up the environment in different
ways or otherwise changing its initialization.

# in tools/my_tool.py:
def generate(env, **kwargs):
# Sets MY_TOOL to the value of keyword 'arg1' or '1' if not supplied
env['MY_TOOL'] = kwargs.get('arg1', '1')

def exists(env):
return True

# in SConstruct:
env = Environment(
tools=['default', ('my_tool', {'arg1': 'abc'})], toolpath=['tools']
)

The tool specification (my_tool in the example) can use the $PLATFORM
variable from the construction environment it is passed to customize
the tool for different platforms.

Tools can be "nested" - that is, they can be located within a
subdirectory in the toolpath. A nested tool name uses a dot to
represent a directory separator

# namespaced builder
env = Environment(ENV=os.environ.copy(), tools=['SubDir1.SubDir2.SomeTool'])
env.SomeTool(targets, sources)

# Search Paths
# SCons\Tool\SubDir1\SubDir2\SomeTool.py
# SCons\Tool\SubDir1\SubDir2\SomeTool\__init__.py
# .\site_scons\site_tools\SubDir1\SubDir2\SomeTool.py
# .\site_scons\site_tools\SubDir1\SubDir2\SomeTool\__init__.py

SYSTEM-SPECIFIC BEHAVIOR
scons and its configuration files are very portable, due largely to
its implementation in Python. There are, however, a few portability
issues waiting to trap the unwary.

.C File Suffix
scons handles the upper-case .C file suffix differently, depending on
the capabilities of the underlying system. On a case-sensitive system
such as Linux or UNIX, scons treats a file with a .C suffix as a C++
source file. On a case-insensitive system such as Windows, scons
treats a file with a .C suffix as a C source file.

Fortran File Suffixes

There are several ways source file suffixes impact the behavior of
SCons when working with Fortran language code (not all are
system-specific, but they are included here for completeness).

As the Fortran language has evolved through multiple standards
editions, projects might have a need to handle files from different
language generations differently. To this end, SCons dispatches to a
different compiler dialect setup (expressed as a set of construction
variables) depending on the file suffix. By default, all of these
setups start out the same, but individual construction variables can
be modified as needed to tune a given dialect. Each of these dialects
has a tool specification module whose documentation describes the
construction variables associated with that dialect: .f (as well as
.for and .ftn) in fortran; (construction variables start with
FORTRAN) .f77 in f77; (construction variables start with F77) .f90 in
f90; (construction variables start with F90) .f95 in f95;
(construction variables start with F95) .f03 in f03; (construction
variables start with F03) .f08 in f08 (construction variables start
with F08).

While SCons recognizes multiple internal dialects based on filename
suffixes, the convention of various available Fortran compilers is to
assign an actual meaning to only two of these suffixes: .f (as well
as .for and .ftn) refers to the fixed-format source code that was the
only available option in FORTRAN 77 and earlier, and .f90 refers to
free-format source code which became available as of the Fortran 90
standard. Some compilers recognize suffixes which correspond to
Fortran specifications later than F90 as equivalent to .f90 for this
purpose, while some do not - check the documentation for your
compiler. An occasionally suggested policy suggestion is to use only
.f and .f90 as Fortran filename suffixes. The fixed/free form
determination can usually be controlled explicitly with compiler
flags (e.g. -ffixed-form for gfortran), overriding any assumption
that may be made based on the source file suffix.

The source file suffix does not imply conformance with the
similarly-named Fortran standard - a suffix of .f08 does not mean you
are compiling specifically for Fortran 2008. Normally, compilers
provide command-line options for making this selection (e.g.
-std=f2008 for gfortran).

For dialects from F90 on (including the generic FORTRAN dialect), a
suffix of .mod is recognized for Fortran modules. These files are a
side effect of compiling a Fortran source file containing module
declarations, and must be available when other code which declares
that it uses the module is processed. SCons does not currently have
integrated support for submodules, introduced in the Fortran 2008
standard - the invoked compiler will produce results, but SCons will
not recognize .smod files as tracked objects.

On a case-sensitive system such as Linux or UNIX, a file with a an
upper-cased suffix from the set .F, .FOR, .FTN, .F90, .F95, .F03 and
.F08 is treated as a Fortran source file which shall first be run
through the standard C preprocessor. The lower-cased versions of
these suffixes do not trigger this behavior. On systems which do not
distinguish between upper and lower case in filenames, this behavior
is not available, but files suffixed with either .FPP or .fpp are
always passed to the preprocessor first. This matches the convention
of gfortran from the GNU Compiler Collection, and also followed by
certain other Fortran compilers. For these two suffixes, the generic
FORTRAN dialect will be selected.

SCons itself does not invoke the preprocessor, that is handled by the
compiler, but it adds construction variables which are applicable to
the preprocessor run. You can see this difference by examining
$FORTRANPPCOM and $FORTRANPPCOMSTR which are used instead of
$FORTRANCOM and $FORTRANCOMSTR for that dialect.

Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons
Cygwin supplies a set of tools and utilities that let users work on a
Windows system using a POSIX-like environment. The Cygwin tools,
including Cygwin Python, do this, in part, by sharing an ability to
interpret POSIX-style path names. For example, the Cygwin tools will
internally translate a Cygwin path name like /cygdrive/c/mydir to an
equivalent Windows pathname of C:/mydir (equivalent to C:\mydir).

Versions of Python that are built for native Windows execution, such
as the python.org and ActiveState versions, do not understand the
Cygwin path name semantics. This means that using a native Windows
version of Python to build compiled programs using Cygwin tools (such
as gcc, bison and flex) may yield unpredictable results. "Mixing and
matching" in this way can be made to work, but it requires careful
attention to the use of path names in your SConscript files.

In practice, users can sidestep the issue by adopting the following
guidelines: When using Cygwin's gcc for compiling, use the
Cygwin-supplied Python interpreter to run scons; when using Microsoft
Visual C++ (or some other "native" Windows compiler) use the
python.org, Microsoft Store, ActiveState or other native version of
Python to run scons.

This discussion largely applies to the msys2 environment as well
(with the use of the mingw compiler toolchain), in particular the
recommendation to use the msys2 version of Python if running scons
from inside an msys2 shell.

Windows: scons.bat file
On Windows, if scons is executed via a wrapper scons.bat batch file,
there are (at least) two ramifications. Note this is no longer the
default - scons installed via Python's pip installer will have a
scons.exe which does not have these limitations:

First, Windows command-line users that want to use variable
assignment on the command line may have to put double quotes around
the assignments, otherwise the Windows command shell will consume
those as arguments to itself, not to scons:

scons "FOO=BAR" "BAZ=BLEH"

Second, the Cygwin shell does not recognize typing scons at the
command line prompt as referring to this wrapper. You can work around
this either by executing scons.bat (including the extension) from the
Cygwin command line, or by creating a wrapper shell script named
scons which invokes scons.bat.

MinGW

The MinGW bin directory must be in your PATH environment variable or
the ['ENV']['PATH'] construction variable for scons to detect and use
the MinGW tools. When running under the native Windows Python
interpreter, scons will prefer the MinGW tools over the Cygwin tools,
if they are both installed, regardless of the order of the bin
directories in the PATH variable. If you have both MSVC and MinGW
installed and you want to use MinGW instead of MSVC, then you must
explicitly tell scons to use MinGW by passing tools=['mingw'] to the
Environment function, because scons will prefer the MSVC tools over
the MinGW tools.

ENVIRONMENT

In general, scons is not controlled by environment variables set in
the shell used to invoke it, leaving it up to the SConscript file
author to import those if desired. However, the following variables
are imported by scons itself if set:

SCONS_LIB_DIR
Specifies the directory that contains the scons Python module
directory. Normally scons can deduce this, but in some
circumstances, such as working with a source release, it may be
necessary to specify (for example,
/home/aroach/scons-src-0.01/src/engine).

SCONSFLAGS
A string containing options that will be used by scons in
addition to those passed on the command line. Can be used to
reduce frequent retyping of common options. The contents of
SCONSFLAGS are considered before any passed command line options,
so the command line can be used to override SCONSFLAGS options if
necessary.

SCONS_CACHE_MSVC_CONFIG
(Windows only). If set, save the shell environment variables
generated when setting up the Microsoft Visual C++ compiler
(and/or Build Tools) to a cache file, to give these settings
persistence across scons invocations. Generating this information
is relatively expensive, so using this option may aid performance
where scons is run often, such as Continuous Integration setups.

If set to a True-like value ("1", "true" or "True") will cache to
a file named scons_msvc_cache.json in the user's home directory.
If set to a pathname, will use that pathname for the cache.

Note: this implementation may still be somewhat fragile. In case
of problems, remove the cache file - recreating with fresh info
normally resolves any issues. SCons ignores failures reading or
writing the cache file and will silently revert to non-cached
behavior in such cases.

New in 3.1 (experimental). The default cache file name was
changed to its present value in 4.4, and contents were expanded.

QTDIR
If using the qt tool, this is the path to the Qt installation to
build against. SCons respects this setting because it is a
long-standing convention in the Qt world, where multiple Qt
installations are possible.

SEE ALSO

The SCons User Guide at
https://scons.org/doc/production/HTML/scons-user.html

The SCons Design Document (old)

The SCons Cookbook at
https://scons-cookbook.readthedocs.io
for examples of how to solve various problems with SCons.


SCons source code
on GitHub[10]


The SCons API Reference
https://scons.org/doc/production/HTML/scons-api/index.html
(for internal details)

AUTHORS

Originally: Steven Knight knight@baldmt.com and Anthony Roach
aroach@electriceyeball.com.

Since 2010: The SCons Development Team scons-dev@scons.org.

AUTHOR

The SCons Development Team

COPYRIGHT

Copyright (C) 2001 - 2025 The SCons Foundation

NOTES

1. https://github.com/SCons/scons-contrib
https://github.com/SCons/scons-contrib

2. LLVM specification
https://clang.llvm.org/docs/JSONCompilationDatabase.html

3. JEP 313
https:openjdk.java.net/jeps/313

4. https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-
file-structure
https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-
file-structure

5. https://learn.microsoft.com/en-
us/visualstudio/extensibility/internals/solution-dot-sln-file
https://learn.microsoft.com/en-
us/visualstudio/extensibility/internals/solution-dot-sln-file

6. optparse documentation
https://docs.python.org/3/library/optparse.html

7. If no_progress is set via SetOption in an SConscript file (but
not if set in a site_init.py file) there will still be an initial
status message about reading SConscript files since SCons has to
start reading them before it can see the SetOption.

8. http://www.opensource.org/licenses/alphabetical
http://www.opensource.org/licenses/alphabetical

9. os.chmod
https://docs.python.org/3/library/os.html#os.chmod

10. on GitHub
https://github.com/SCons/scons

SCons 4.9.1 Version 4.9.1
<pubdate>Released Thu, 27 Mar 2025 11:44:24 -0700</pubdate>
SCONS(1)