FvwmCpp(1) Fvwm Modules FvwmCpp(1)

NAME

FvwmCpp - the Fvwm Cpp pre-processor

SYNOPSIS

Module FvwmCpp [options] filename

The FvwmCpp module can only be invoked by fvwm. Command line
invocation of the FvwmCpp module will not work.

DESCRIPTION

When fvwm executes the FvwmCpp module, FvwmCpp invokes the cpp pre-
processor on the file specified in its invocation, then FvwmCpp
causes fvwm to execute the commands in the resulting file.

INVOCATION

FvwmCpp can be invoked as a module using an fvwm command, from the
.fvwm2rc file, a menu, mousebinding, or any of the many other ways
fvwm commands can be issued.

If the user wants his entire .fvwm2rc file pre-processed with
FvwmCpp, then fvwm should be invoked as:

fvwm -cmd "Module FvwmCpp .fvwm2rc"

Note that the argument to the option "-cmd" should be enclosed in
quotes, and no other quoting should be used.

When FvwmCpp runs as a module, it runs asynchronously from fvwm. If
FvwmCpp is invoked from the .fvwm2rc, the commands generated by
FvwmCpp may or may not be executed by the time fvwm processes the
next command in the .fvwm2rc. Invoke FvwmCpp this way for
synchronous execution:

ModuleSynchronous FvwmCpp -lock filename

OPTIONS

Some options can be specified following the modulename:

-cppopt option
Lets you pass an option to the cpp program. Not really needed
as any unknown options will be passed on automatically.


-cppprog name
Instead of invoking "/usr/lib/cpp", fvwm will invoke name.


-outfile filename
Instead of creating a random unique name for the temporary
file for the preprocessed rc file, this option will let you
specify the name of the temporary file it will create. Please
note that FvwmCpp will attempt to remove this file before
writing to it, so don't point it at anything important even if
it has read-only protection.


-debug Causes the temporary file create by Cpp to be retained. This
file is usually called "/tmp/fvwmrcXXXXXX"


-lock If you want to use this option you need to start FvwmCpp with
ModuleSynchronous. This option causes fvwm to wait that the
pre-process finish and that FvwmCpp asks fvwm to Read the pre-
processed file before continuing. This may be useful at
startup if you use a session manager as Gnome. Also, this is
useful if you want to process and run a Form in a fvwm
function.


-noread
Causes the pre-processed file to be not read by fvwm. Useful
to pre-process a FvwmScript script with FvwmCpp.

CONFIGURATION OPTIONS

FvwmCpp defines some values for use in the pre-processor file:


TWM_TYPE
Always set to "fvwm".

SERVERHOST
The name of the machine running the X Server.

CLIENTHOST
The name of the machine running fvwm.

HOSTNAME
The host name of the machine running fvwm. Generally the same
as CLIENTHOST.

OSTYPE The operating system for CLIENTHOST.

USER The name of the person running fvwm.

HOME The home directory of the person running fvwm.

VERSION
The X11 version.

REVISION
The X11 revision number.

VENDOR The X server vendor.

RELEASE
The X server release number.

SCREEN The screen number.

WIDTH The screen width in pixels.

HEIGHT The screen height in pixels.

X_RESOLUTION
Some distance/pixel measurement for the horizontal direction,
I think.

Y_RESOLUTION
Some distance/pixel measurement for the vertical direction, I
think.

PLANES Number of color planes for the X server display

BITS_PER_RGB
Number of bits in each rgb triplet.

CLASS The X11 default visual class, e.g. PseudoColor.

COLOR Yes or No, Yes if the default visual class is neither
StaticGrey or GreyScale.

FVWM_CLASS
The visual class that fvwm is using, e.g. TrueColor.

FVWM_COLOR
Yes or No, Yes if the FVWM_CLASS is neither StaticGrey or
GreyScale.

FVWM_VERSION
The fvwm version number, ie 2.0

OPTIONS
Some combination of SHAPE, XPM, NO_SAVEUNDERS, and Cpp, as
defined in configure.h at compile time.

FVWM_MODULEDIR
The directory where fvwm looks for .fvwm2rc and modules by
default, as determined at compile time.

FVWM_USERDIR
The value of $FVWM_USERDIR.

SESSION_MANAGER
The value of $SESSION_MANAGER. Undefined if this variable is
not set.

EXAMPLE PROLOG

#define TWM_TYPE fvwm
#define SERVERHOST spx20
#define CLIENTHOST grumpy
#define HOSTNAME grumpy
#define OSTYPE SunOS
#define USER nation
#define HOME /local/homes/dsp/nation
#define VERSION 11
#define REVISION 0
#define VENDOR HDS human designed systems, inc. (2.1.2-D)
#define RELEASE 4
#define SCREEN 0
#define WIDTH 1280
#define HEIGHT 1024
#define X_RESOLUTION 3938
#define Y_RESOLUTION 3938
#define PLANES 8
#define BITS_PER_RGB 8
#define CLASS PseudoColor
#define COLOR Yes
#define FVWM_VERSION 2.0 pl 1
#define OPTIONS SHAPE XPM Cpp
#define FVWM_MODULEDIR /local/homes/dsp/nation/modules
#define FVWM_USERDIR /local/homes/dsp/nation/.fvwm
#define SESSION_MANAGER local/grumpy:/tmp/.ICE-unix/440,tcp/spx20:1025

BUGS

Module configurations do not become active until fvwm has restarted
if you use FvwmCpp on startup. FvwmCpp creates a temporary file and
passes this to fvwm, so you would have to edit this file too. There
are some problems with comments in your .fvwm2rc file. The comment
sign # is misinterpreted by the preprocessor. This has usually no
impact on functionality but generates annoying warning messages. The
sequence /* is interpreted as the start of a C comment what is
probably not what you want in a filename. You might want to try /?*
(for filenames only) or /\* or "/*" instead. Depending on your
preprocessor you may have the same problem with "//". Macros are not
replaced within single (') or double quotes ( back quotes (`) to
circumvent this. Fvwm accepts back quotes for quoting and at least
FvwmButtons does too. The preprocessor may place a space after a
macro substitution, so with
#define MYCOMMAND ls
"Exec "MYCOMMAND" -l"
you might get
"Exec "ls " -l" (two words)
and not
"Exec "ls" -l" (one word).

If you use gcc you can use this invocation to turn off '//' comments:

FvwmCpp -Cppprog '/your/path/to/gcc -C -E -' <filename>

AUTHOR

FvwmCpp is the result of a random bit mutation on a hard disk,
presumably a result of a cosmic-ray or some such thing.

3rd Berkeley Distribution 19 October 2022 (2.7.0) FvwmCpp(1)