ZSHCOMPSYS(1) User Commands ZSHCOMPSYS(1)

NAME

zshcompsys - zsh completion system

DESCRIPTION

This describes the shell code for the `new' completion system,
referred to as compsys. It is written in shell functions based on
the features described in zshcompwid(1).

The features are contextual, sensitive to the point at which
completion is started. Many completions are already provided. For
this reason, a user can perform a great many tasks without knowing
any details beyond how to initialize the system, which is described
below in INITIALIZATION.

The context that decides what completion is to be performed may be
+o an argument or option position: these describe the position on
the command line at which completion is requested. For
example `first argument to rmdir, the word being completed
names a directory';


+o a special context, denoting an element in the shell's syntax.
For example `a word in command position' or `an array
subscript'.


A full context specification contains other elements, as we shall
describe.

Besides commands names and contexts, the system employs two more
concepts, styles and tags. These provide ways for the user to
configure the system's behaviour.

Tags play a dual role. They serve as a classification system for the
matches, typically indicating a class of object that the user may
need to distinguish. For example, when completing arguments of the
ls command the user may prefer to try files before directories, so
both of these are tags. They also appear as the rightmost element in
a context specification.

Styles modify various operations of the completion system, such as
output formatting, but also what kinds of completers are used (and in
what order), or which tags are examined. Styles may accept arguments
and are manipulated using the zstyle command described in
zshmodules(1).

In summary, tags describe what the completion objects are, and style
how they are to be completed. At various points of execution, the
completion system checks what styles and/or tags are defined for the
current context, and uses that to modify its behavior. The full
description of context handling, which determines how tags and other
elements of the context influence the behaviour of styles, is
described below in COMPLETION SYSTEM CONFIGURATION.

When a completion is requested, a dispatcher function is called; see
the description of _main_complete in the list of control functions
below. This dispatcher decides which function should be called to
produce the completions, and calls it. The result is passed to one or
more completers, functions that implement individual completion
strategies: simple completion, error correction, completion with
error correction, menu selection, etc.

More generally, the shell functions contained in the completion
system are of two types:
+o those beginning `comp' are to be called directly; there are
only a few of these;


+o those beginning `_' are called by the completion code. The
shell functions of this set, which implement completion
behaviour and may be bound to keystrokes, are referred to as
`widgets'. These proliferate as new completions are required.

INITIALIZATION

If the system was installed completely, it should be enough to call
the shell function compinit from your initialization file; see the
next section. However, the function compinstall can be run by a user
to configure various aspects of the completion system.

Usually, compinstall will insert code into .zshrc, although if that
is not writable it will save it in another file and tell you that
file's location. Note that it is up to you to make sure that the
lines added to .zshrc are actually run; you may, for example, need to
move them to an earlier place in the file if .zshrc usually returns
early. So long as you keep them all together (including the comment
lines at the start and finish), you can rerun compinstall and it will
correctly locate and modify these lines. Note, however, that any
code you add to this section by hand is likely to be lost if you
rerun compinstall, although lines using the command `zstyle' should
be gracefully handled.

The new code will take effect next time you start the shell, or run
.zshrc by hand; there is also an option to make them take effect
immediately. However, if compinstall has removed definitions, you
will need to restart the shell to see the changes.

To run compinstall you will need to make sure it is in a directory
mentioned in your fpath parameter, which should already be the case
if zsh was properly configured as long as your startup files do not
remove the appropriate directories from fpath. Then it must be
autoloaded (`autoload -U compinstall' is recommended). You can abort
the installation any time you are being prompted for information, and
your .zshrc will not be altered at all; changes only take place right
at the end, where you are specifically asked for confirmation.

Use of compinit

This section describes the use of compinit to initialize completion
for the current session when called directly; if you have run
compinstall it will be called automatically from your .zshrc.

To initialize the system, the function compinit should be in a
directory mentioned in the fpath parameter, and should be autoloaded
(`autoload -U compinit' is recommended), and then run simply as
`compinit'. This will define a few utility functions, arrange for
all the necessary shell functions to be autoloaded, and will then
re-define all widgets that do completion to use the new system. If
you use the menu-select widget, which is part of the zsh/complist
module, you should make sure that that module is loaded before the
call to compinit so that that widget is also re-defined. If
completion styles (see below) are set up to perform expansion as well
as completion by default, and the TAB key is bound to
expand-or-complete, compinit will rebind it to complete-word; this is
necessary to use the correct form of expansion.

Should you need to use the original completion commands, you can
still bind keys to the old widgets by putting a `.' in front of the
widget name, e.g. `.expand-or-complete'.

To speed up the running of compinit, it can be made to produce a
dumped configuration that will be read in on future invocations; this
is the default, but can be turned off by calling compinit with the
option -D. The dumped file is .zcompdump in the same directory as
the startup files (i.e. $ZDOTDIR or $HOME); alternatively, an
explicit file name can be given by `compinit -d dumpfile'. The next
invocation of compinit will read the dumped file instead of
performing a full initialization.

If the number of completion files changes, compinit will recognise
this and produce a new dump file. However, if the name of a function
or the arguments in the first line of a #compdef function (as
described below) change, it is easiest to delete the dump file by
hand so that compinit will re-create it the next time it is run. The
check performed to see if there are new functions can be omitted by
giving the option -C. In this case the dump file will only be
created if there isn't one already.

The dumping is actually done by another function, compdump, but you
will only need to run this yourself if you change the configuration
(e.g. using compdef) and then want to dump the new one. The name of
the old dumped file will be remembered for this purpose.

If the parameter _compdir is set, compinit uses it as a directory
where completion functions can be found; this is only necessary if
they are not already in the function search path.

For security reasons compinit also checks if the completion system
would use files not owned by root or by the current user, or files in
directories that are world- or group-writable or that are not owned
by root or by the current user. If such files or directories are
found, compinit will ask if the completion system should really be
used. To avoid these tests and make all files found be used without
asking, use the option -u, and to make compinit silently ignore all
insecure files and directories use the option -i. This security
check is skipped entirely when the -C option is given, provided the
dumpfile exists.

The security check can be retried at any time by running the function
compaudit. This is the same check used by compinit, but when it is
executed directly any changes to fpath are made local to the function
so they do not persist. The directories to be checked may be passed
as arguments; if none are given, compaudit uses fpath and _compdir to
find completion system directories, adding missing ones to fpath as
necessary. To force a check of exactly the directories currently
named in fpath, set _compdir to an empty string before calling
compaudit or compinit.

The function bashcompinit provides compatibility with bash's
programmable completion system. When run it will define the
functions, compgen and complete which correspond to the bash builtins
with the same names. It will then be possible to use completion
specifications and functions written for bash.

Autoloaded files

The convention for autoloaded functions used in completion is that
they start with an underscore; as already mentioned, the fpath/FPATH
parameter must contain the directory in which they are stored. If
zsh was properly installed on your system, then fpath/FPATH
automatically contains the required directories for the standard
functions.

For incomplete installations, if compinit does not find enough files
beginning with an underscore (fewer than twenty) in the search path,
it will try to find more by adding the directory _compdir to the
search path. If that directory has a subdirectory named Base, all
subdirectories will be added to the path. Furthermore, if the
subdirectory Base has a subdirectory named Core, compinit will add
all subdirectories of the subdirectories to the path: this allows the
functions to be in the same format as in the zsh source distribution.

When compinit is run, it searches all such files accessible via
fpath/FPATH and reads the first line of each of them. This line
should contain one of the tags described below. Files whose first
line does not start with one of these tags are not considered to be
part of the completion system and will not be treated specially.

The tags are:

#compdef name ... [ -{p|P} pattern ... [ -N name ... ] ]
The file will be made autoloadable and the function defined in
it will be called when completing names, each of which is
either the name of a command whose arguments are to be
completed or one of a number of special contexts in the form
-context- described below.

Each name may also be of the form `cmd=service'. When
completing the command cmd, the function typically behaves as
if the command (or special context) service was being
completed instead. This provides a way of altering the
behaviour of functions that can perform many different
completions. It is implemented by setting the parameter
$service when calling the function; the function may choose to
interpret this how it wishes, and simpler functions will
probably ignore it.

If the #compdef line contains one of the options -p or -P, the
words following are taken to be patterns. The function will
be called when completion is attempted for a command or
context that matches one of the patterns. The options -p and
-P are used to specify patterns to be tried before or after
other completions respectively. Hence -P may be used to
specify default actions.

The option -N is used after a list following -p or -P; it
specifies that remaining words no longer define patterns. It
is possible to toggle between the three options as many times
as necessary.

#compdef -k style key-sequence ...
This option creates a widget behaving like the builtin widget
style and binds it to the given key-sequences, if any. The
style must be one of the builtin widgets that perform
completion, namely complete-word, delete-char-or-list,
expand-or-complete, expand-or-complete-prefix, list-choices,
menu-complete, menu-expand-or-complete, or
reverse-menu-complete. If the zsh/complist module is loaded
(see zshmodules(1)) the widget menu-select is also available.

When one of the key-sequences is typed, the function in the
file will be invoked to generate the matches. Note that a key
will not be re-bound if it already was (that is, was bound to
something other than undefined-key). The widget created has
the same name as the file and can be bound to any other keys
using bindkey as usual.

#compdef -K widget-name style key-sequence [ name style seq ... ]
This is similar to -k except that only one key-sequence
argument may be given for each widget-name style pair.
However, the entire set of three arguments may be repeated
with a different set of arguments. Note in particular that
the widget-name must be distinct in each set. If it does not
begin with `_' this will be added. The widget-name should not
clash with the name of any existing widget: names based on the
name of the function are most useful. For example,

#compdef -K _foo_complete complete-word "^X^C" \
_foo_list list-choices "^X^D"

(all on one line) defines a widget _foo_complete for
completion, bound to `^X^C', and a widget _foo_list for
listing, bound to `^X^D'.

#autoload [ options ]
Functions with the #autoload tag are marked for autoloading
but are not otherwise treated specially. Typically they are
to be called from within one of the completion functions. Any
options supplied will be passed to the autoload builtin; a
typical use is +X to force the function to be loaded
immediately. Note that the -U and -z flags are always added
implicitly.

The # is part of the tag name and no white space is allowed after it.
The #compdef tags use the compdef function described below; the main
difference is that the name of the function is supplied implicitly.

The special contexts for which completion functions can be defined
are:

-array-value-
The right hand side of an array-assignment (`name=(...)')

-assign-parameter-
The name of a parameter in an assignment, i.e. on the left
hand side of an `='

-brace-parameter-
The name of a parameter expansion within braces (`${...}')

-command-
A word in command position

-condition-
A word inside a condition (`[[...]]')

-default-
Any word for which no other completion is defined

-equal-
A word beginning with an equals sign

-first-
This is tried before any other completion function. The
function called may set the _compskip parameter to one of
various values: all: no further completion is attempted; a
string containing the substring patterns: no pattern
completion functions will be called; a string containing
default: the function for the `-default-' context will not be
called, but functions defined for commands will be.

-math- Inside mathematical contexts, such as `((...))'

-parameter-
The name of a parameter expansion (`$...')

-redirect-
The word after a redirection operator.

-subscript-
The contents of a parameter subscript.

-tilde-
After an initial tilde (`~'), but before the first slash in
the word.

-value-
On the right hand side of an assignment.

Default implementations are supplied for each of these contexts. In
most cases the context -context- is implemented by a corresponding
function _context, for example the context `-tilde-' and the function
`_tilde').

The contexts -redirect- and -value- allow extra context-specific
information. (Internally, this is handled by the functions for each
context calling the function _dispatch.) The extra information is
added separated by commas.

For the -redirect- context, the extra information is in the form
`-redirect-,op,command', where op is the redirection operator and
command is the name of the command on the line. If there is no
command on the line yet, the command field will be empty.

For the -value- context, the form is `-value-,name,command', where
name is the name of the parameter on the left hand side of the
assignment. In the case of elements of an associative array, for
example `assoc=(key <TAB>', name is expanded to `name-key'. In
certain special contexts, such as completing after `make CFLAGS=',
the command part gives the name of the command, here make; otherwise
it is empty.

It is not necessary to define fully specific completions as the
functions provided will try to generate completions by progressively
replacing the elements with `-default-'. For example, when
completing after `foo=<TAB>', _value will try the names
`-value-,foo,' (note the empty command part), `-value-,foo,-default-'
and`-value-,-default-,-default-', in that order, until it finds a
function to handle the context.

As an example:

compdef '_files -g "*.log"' '-redirect-,2>,-default-'

completes files matching `*.log' after `2> <TAB>' for any command
with no more specific handler defined.

Also:

compdef _foo -value-,-default-,-default-

specifies that _foo provides completions for the values of parameters
for which no special function has been defined. This is usually
handled by the function _value itself.

The same lookup rules are used when looking up styles (as described
below); for example

zstyle ':completion:*:*:-redirect-,2>,*:*' file-patterns '*.log'

is another way to make completion after `2> <TAB>' complete files
matching `*.log'.

Functions

The following function is defined by compinit and may be called
directly.


compdef [ -ane ] function name ... [ -{p|P} pattern ... [ -N name
...]]
compdef -d name ...
compdef -k [ -an ] function style key-sequence [ key-sequence ... ]
compdef -K [ -an ] function name style key-seq [ name style seq ... ]
The first form defines the function to call for completion in
the given contexts as described for the #compdef tag above.

Alternatively, all the arguments may have the form
`cmd=service'. Here service should already have been defined
by `cmd1=service' lines in #compdef files, as described above.
The argument for cmd will be completed in the same way as
service.

The function argument may alternatively be a string containing
almost any shell code. If the string contains an equal sign,
the above will take precedence. The option -e may be used to
specify the first argument is to be evaluated as shell code
even if it contains an equal sign. The string will be
executed using the eval builtin command to generate
completions. This provides a way of avoiding having to define
a new completion function. For example, to complete files
ending in `.h' as arguments to the command foo:

compdef '_files -g "*.h"' foo

The option -n prevents any completions already defined for the
command or context from being overwritten.

The option -d deletes any completion defined for the command
or contexts listed.

The names may also contain -p, -P and -N options as described
for the #compdef tag. The effect on the argument list is
identical, switching between definitions of patterns tried
initially, patterns tried finally, and normal commands and
contexts.

The parameter $_compskip may be set by any function defined
for a pattern context. If it is set to a value containing the
substring `patterns' none of the pattern-functions will be
called; if it is set to a value containing the substring
`all', no other function will be called. Setting $_compskip
in this manner is of particular utility when using the -p
option, as otherwise the dispatcher will move on to additional
functions (likely the default one) after calling the
pattern-context one, which can mangle the display of
completion possibilities if not handled properly.

The form with -k defines a widget with the same name as the
function that will be called for each of the key-sequences;
this is like the #compdef -k tag. The function should
generate the completions needed and will otherwise behave like
the builtin widget whose name is given as the style argument.
The widgets usable for this are: complete-word,
delete-char-or-list, expand-or-complete,
expand-or-complete-prefix, list-choices, menu-complete,
menu-expand-or-complete, and reverse-menu-complete, as well as
menu-select if the zsh/complist module is loaded. The option
-n prevents the key being bound if it is already to bound to
something other than undefined-key.

The form with -K is similar and defines multiple widgets based
on the same function, each of which requires the set of three
arguments name, style and key-sequence, where the latter two
are as for -k and the first must be a unique widget name
beginning with an underscore.

Wherever applicable, the -a option makes the function
autoloadable, equivalent to autoload -U function.

The function compdef can be used to associate existing completion
functions with new commands. For example,

compdef _pids foo

uses the function _pids to complete process IDs for the command foo.

Note also the _gnu_generic function described below, which can be
used to complete options for commands that understand the `--help'
option.

COMPLETION SYSTEM CONFIGURATION

This section gives a short overview of how the completion system
works, and then more detail on how users can configure how and when
matches are generated.

Overview

When completion is attempted somewhere on the command line the
completion system begins building the context. The context
represents everything that the shell knows about the meaning of the
command line and the significance of the cursor position. This takes
account of a number of things including the command word (such as
`grep' or `zsh') and options to which the current word may be an
argument (such as the `-o' option to zsh which takes a shell option
as an argument).

The context starts out very generic ("we are beginning a completion")
and becomes more specific as more is learned ("the current word is in
a position that is usually a command name" or "the current word might
be a variable name" and so on). Therefore the context will vary
during the same call to the completion system.

This context information is condensed into a string consisting of
multiple fields separated by colons, referred to simply as `the
context' in the remainder of the documentation. Note that a user of
the completion system rarely needs to compose a context string,
unless for example a new function is being written to perform
completion for a new command. What a user may need to do is compose
a style pattern, which is matched against a context when needed to
look up context-sensitive options that configure the completion
system.

The next few paragraphs explain how a context is composed within the
completion function suite. Following that is discussion of how
styles are defined. Styles determine such things as how the matches
are generated, similarly to shell options but with much more control.
They are defined with the zstyle builtin command (see zshmodules(1)).

The context string always consists of a fixed set of fields,
separated by colons and with a leading colon before the first.
Fields which are not yet known are left empty, but the surrounding
colons appear anyway. The fields are always in the order
:completion:function:completer:command:argument:tag. These have the
following meaning:

+o The literal string completion, saying that this style is used
by the completion system. This distinguishes the context from
those used by, for example, zle widgets and ZFTP functions.


+o The function, if completion is called from a named widget
rather than through the normal completion system. Typically
this is blank, but it is set by special widgets such as
predict-on and the various functions in the Widget directory
of the distribution to the name of that function, often in an
abbreviated form.


+o The completer currently active, the name of the function
without the leading underscore and with other underscores
converted to hyphens. A `completer' is in overall control of
how completion is to be performed; `complete' is the simplest,
but other completers exist to perform related tasks such as
correction, or to modify the behaviour of a later completer.
See the section `Control Functions' below for more
information.


+o The command or a special -context-, just at it appears
following the #compdef tag or the compdef function.
Completion functions for commands that have sub-commands
usually modify this field to contain the name of the command
followed by a minus sign and the sub-command. For example,
the completion function for the cvs command sets this field to
cvs-add when completing arguments to the add subcommand.


+o The argument; this indicates which command line or option
argument we are completing. For command arguments this
generally takes the form argument-n, where n is the number of
the argument, and for arguments to options the form
option-opt-n where n is the number of the argument to option
opt. However, this is only the case if the command line is
parsed with standard UNIX-style options and arguments, so many
completions do not set this.


+o The tag. As described previously, tags are used to
discriminate between the types of matches a completion
function can generate in a certain context. Any completion
function may use any tag name it likes, but a list of the more
common ones is given below.


The context is gradually put together as the functions are executed,
starting with the main entry point, which adds :completion: and the
function element if necessary. The completer then adds the completer
element. The contextual completion adds the command and argument
options. Finally, the tag is added when the types of completion are
known. For example, the context name

:completion::complete:dvips:option-o-1:files

says that normal completion was attempted as the first argument to
the option -o of the command dvips:

dvips -o ...

and the completion function will generate filenames.

Usually completion will be tried for all possible tags in an order
given by the completion function. However, this can be altered by
using the tag-order style. Completion is then restricted to the list
of given tags in the given order.

The _complete_help bindable command shows all the contexts and tags
available for completion at a particular point. This provides an
easy way of finding information for tag-order and other styles. It
is described in the section `Bindable Commands' below.

When looking up styles the completion system uses full context names,
including the tag. Looking up the value of a style therefore
consists of two things: the context, which is matched to the most
specific (best fitting) pattern, and the name of the style itself,
which must be matched exactly. The following examples demonstrate
that patterns may be loosely defined for styles that apply broadly,
or as tightly defined as desired for styles that apply in narrower
circumstances.

For example, many completion functions can generate matches in a
simple and a verbose form and use the verbose style to decide which
form should be used. To make all such functions use the verbose
form, put

zstyle ':completion:*' verbose yes

in a startup file (probably .zshrc). This gives the verbose style
the value yes in every context inside the completion system, unless
that context has a more specific definition. It is best to avoid
giving the pattern as `*' in case the style has some meaning outside
the completion system.

Many such general purpose styles can be configured simply by using
the compinstall function.

A more specific example of the use of the verbose style is by the
completion for the kill builtin. If the style is set, the builtin
lists full job texts and process command lines; otherwise it shows
the bare job numbers and PIDs. To turn the style off for this use
only:

zstyle ':completion:*:*:kill:*:*' verbose no

For even more control, the style can use one of the tags `jobs' or
`processes'. To turn off verbose display only for jobs:

zstyle ':completion:*:*:kill:*:jobs' verbose no

The -e option to zstyle even allows completion function code to
appear as the argument to a style; this requires some understanding
of the internals of completion functions (see see zshcompwid(1))).
For example,

zstyle -e ':completion:*' hosts 'reply=($myhosts)'

This forces the value of the hosts style to be read from the variable
myhosts each time a host name is needed; this is useful if the value
of myhosts can change dynamically. For another useful example, see
the example in the description of the file-list style below. This
form can be slow and should be avoided for commonly examined styles
such as menu and list-rows-first.

Note that the order in which styles are defined does not matter; the
style mechanism uses the most specific possible match for a
particular style to determine the set of values. Strings are
preferred over patterns (for example, `:completion::complete:::foo'
is more specific than `:completion::complete:::*'), and longer
patterns are preferred over the pattern `*'. See zmodules(1) for
details.

Context patterns that use something other than a wildcard (*) to
match the middle parts of the context -- the completer, command, and
argument in :completion:function:completer:command:argument:tag --
should include all six colons (:) explicitly. Without this, a pattern
such as :completion:*:foo:* could match foo against a component other
than the intended one (for example, against completer when a match
against command was intended).

Style names like those of tags are arbitrary and depend on the
completion function. However, the following two sections list some
of the most common tags and styles.

Standard Tags

Some of the following are only used when looking up particular styles
and do not refer to a type of match.

accounts
used to look up the users-hosts style

all-expansions
used by the _expand completer when adding the single string
containing all possible expansions

all-files
for the names of all files (as distinct from a particular
subset, see the globbed-files tag).

arguments
for arguments to a command

arrays for names of array parameters

association-keys
for keys of associative arrays; used when completing inside a
subscript to a parameter of this type

bookmarks
when completing bookmarks (e.g. for URLs and the zftp function
suite)

builtins
for names of builtin commands

characters
for single characters in arguments of commands such as stty.
Also used when completing character classes after an opening
bracket

colormapids
for X colormap ids

colors for color names

commands
for names of external commands. Also used by complex commands
such as cvs when completing names subcommands.

contexts
for contexts in arguments to the zstyle builtin command

corrections
used by the _approximate and _correct completers for possible
corrections

cursors
for cursor names used by X programs

default
used in some contexts to provide a way of supplying a default
when more specific tags are also valid. Note that this tag is
used when only the function field of the context name is set

descriptions
used when looking up the value of the format style to generate
descriptions for types of matches

devices
for names of device special files

directories
for names of directories -- local-directories is used instead
when completing arguments of cd and related builtin commands
when the cdpath array is set

directory-stack
for entries in the directory stack

displays
for X display names

domains
for network domains

email-plugin
for email addresses from the `_email-plugin' backend of
_email_addresses

expansions
used by the _expand completer for individual words (as opposed
to the complete set of expansions) resulting from the
expansion of a word on the command line

extensions
for X server extensions

file-descriptors
for numbers of open file descriptors

files the generic file-matching tag used by functions completing
filenames

fonts for X font names

fstypes
for file system types (e.g. for the mount command)

functions
names of functions -- normally shell functions, although
certain commands may understand other kinds of function

globbed-files
for filenames when the name has been generated by pattern
matching

groups for names of user groups

history-words
for words from the history

hosts for hostnames

indexes
for array indexes

interfaces
for network interfaces

jobs for jobs (as listed by the `jobs' builtin)

keymaps
for names of zsh keymaps

keysyms
for names of X keysyms

libraries
for names of system libraries

limits for system limits

local-directories
for names of directories that are subdirectories of the
current working directory when completing arguments of cd and
related builtin commands (compare path-directories) -- when
the cdpath array is unset, directories is used instead

mailboxes
for e-mail folders

manuals
for names of manual pages

maps for map names (e.g. NIS maps)

messages
used to look up the format style for messages

modifiers
for names of X modifiers

modules
for modules (e.g. zsh modules)

my-accounts
used to look up the users-hosts style

named-directories
for named directories (you wouldn't have guessed that, would
you?)

names for all kinds of names

newsgroups
for USENET groups

nicknames
for nicknames of NIS maps

options
for command options

original
used by the _approximate, _correct and _expand completers when
offering the original string as a match

other-accounts
used to look up the users-hosts style

packages
for packages (e.g. rpm or installed Debian packages)

parameters
for names of parameters

path-directories
for names of directories found by searching the cdpath array
when completing arguments of cd and related builtin commands
(compare local-directories)

paths used to look up the values of the expand, ambiguous and
special-dirs styles

pods for perl pods (documentation files)

ports for communication ports

prefixes
for prefixes (like those of a URL)

printers
for print queue names

processes
for process identifiers

processes-names
used to look up the command style when generating the names of
processes for killall

sequences
for sequences (e.g. mh sequences)

sessions
for sessions in the zftp function suite

signals
for signal names

strings
for strings (e.g. the replacement strings for the cd builtin
command)

styles for styles used by the zstyle builtin command

suffixes
for filename extensions

tags for tags (e.g. rpm tags)

targets
for makefile targets

time-zones
for time zones (e.g. when setting the TZ parameter)

types for types of whatever (e.g. address types for the xhost
command)

urls used to look up the urls and local styles when completing URLs

users for usernames

values for one of a set of values in certain lists

variant
used by _pick_variant to look up the command to run when
determining what program is installed for a particular command
name.

visuals
for X visuals

warnings
used to look up the format style for warnings

widgets
for zsh widget names

windows
for IDs of X windows

zsh-options
for shell options

Standard Styles

Note that the values of several of these styles represent boolean
values. Any of the strings `true', `on', `yes', and `1' can be used
for the value `true' and any of the strings `false', `off', `no', and
`0' for the value `false'. The behavior for any other value is
undefined except where explicitly mentioned. The default value may
be either `true' or `false' if the style is not set.

Some of these styles are tested first for every possible tag
corresponding to a type of match, and if no style was found, for the
default tag. The most notable styles of this type are menu,
list-colors and styles controlling completion listing such as
list-packed and last-prompt. When tested for the default tag, only
the function field of the context will be set so that a style using
the default tag will normally be defined along the lines of:

zstyle ':completion:*:default' menu ...

accept-exact
This is tested for the default tag in addition to the tags
valid for the current context. If it is set to `true' and any
of the trial matches is the same as the string on the command
line, this match will immediately be accepted (even if it
would otherwise be considered ambiguous).

When completing pathnames (where the tag used is `paths') this
style accepts any number of patterns as the value in addition
to the boolean values. Pathnames matching one of these
patterns will be accepted immediately even if the command line
contains some more partially typed pathname components and
these match no file under the directory accepted.

This style is also used by the _expand completer to decide if
words beginning with a tilde or parameter expansion should be
expanded. For example, if there are parameters foo and
foobar, the string `$foo' will only be expanded if
accept-exact is set to `true'; otherwise the completion system
will be allowed to complete $foo to $foobar. If the style is
set to `continue', _expand will add the expansion as a match
and the completion system will also be allowed to continue.

accept-exact-dirs
This is used by filename completion. Unlike accept-exact it
is a boolean. By default, filename completion examines all
components of a path to see if there are completions of that
component, even if the component matches an existing
directory. For example, when completion after /usr/bin/, the
function examines possible completions to /usr.

When this style is `true', any prefix of a path that matches
an existing directory is accepted without any attempt to
complete it further. Hence, in the given example, the path
/usr/bin/ is accepted immediately and completion tried in that
directory.

This style is also useful when completing after directories
that magically appear when referenced, such as ZFS .zfs
directories or NetApp .snapshot directories. When the style
is set the shell does not check for the existence of the
directory within the parent directory.

If you wish to inhibit this behaviour entirely, set the
path-completion style (see below) to `false'.

add-space
This style is used by the _expand completer. If it is `true'
(the default), a space will be inserted after all words
resulting from the expansion, or a slash in the case of
directory names. If the value is `file', the completer will
only add a space to names of existing files. Either a boolean
`true' or the value `file' may be combined with `subst', in
which case the completer will not add a space to words
generated from the expansion of a substitution of the form
`$(...)' or `${...}'.

The _prefix completer uses this style as a simple boolean
value to decide if a space should be inserted before the
suffix.

ambiguous
This applies when completing non-final components of filename
paths, in other words those with a trailing slash. If it is
set, the cursor is left after the first ambiguous component,
even if menu completion is in use. The style is always tested
with the paths tag.

assign-list
When completing after an equals sign that is being treated as
an assignment, the completion system normally completes only
one filename. In some cases the value may be a list of
filenames separated by colons, as with PATH and similar
parameters. This style can be set to a list of patterns
matching the names of such parameters.

The default is to complete lists when the word on the line
already contains a colon.

auto-description
If set, this style's value will be used as the description for
options that are not described by the completion functions,
but that have exactly one argument. The sequence `%d' in the
value will be replaced by the description for this argument.
Depending on personal preferences, it may be useful to set
this style to something like `specify: %d'. Note that this
may not work for some commands.

avoid-completer
This is used by the _all_matches completer to decide if the
string consisting of all matches should be added to the list
currently being generated. Its value is a list of names of
completers. If any of these is the name of the completer that
generated the matches in this completion, the string will not
be added.

The default value for this style is `_expand _old_list
_correct _approximate', i.e. it contains the completers for
which a string with all matches will almost never be wanted.

cache-path
This style defines the path where any cache files containing
dumped completion data are stored. It defaults to
`$ZDOTDIR/.zcompcache', or `$HOME/.zcompcache' if $ZDOTDIR is
not defined. The completion cache will not be used unless the
use-cache style is set.

cache-policy
This style defines the function that will be used to determine
whether a cache needs rebuilding. See the section on the
_cache_invalid function below.

call-command
This style is used in the function for commands such as make
and ant where calling the command directly to generate matches
suffers problems such as being slow or, as in the case of make
can potentially cause actions in the makefile to be executed.
If it is set to `true' the command is called to generate
matches. The default value of this style is `false'.

command
In many places, completion functions need to call external
commands to generate the list of completions. This style can
be used to override the command that is called in some such
cases. The elements of the value are joined with spaces to
form a command line to execute. The value can also start with
a hyphen, in which case the usual command will be added to the
end; this is most useful for putting `builtin' or `command' in
front to make sure the appropriate version of a command is
called, for example to avoid calling a shell function with the
same name as an external command.

As an example, the completion function for process IDs uses
this style with the processes tag to generate the IDs to
complete and the list of processes to display (if the verbose
style is `true'). The list produced by the command should
look like the output of the ps command. The first line is not
displayed, but is searched for the string `PID' (or `pid') to
find the position of the process IDs in the following lines.
If the line does not contain `PID', the first numbers in each
of the other lines are taken as the process IDs to complete.

Note that the completion function generally has to call the
specified command for each attempt to generate the completion
list. Hence care should be taken to specify only commands
that take a short time to run, and in particular to avoid any
that may never terminate.

command-path
This is a list of directories to search for commands to
complete. The default for this style is the value of the
special parameter path.

commands
This is used by the function completing sub-commands for the
system initialisation scripts (residing in /etc/init.d or
somewhere not too far away from that). Its values give the
default commands to complete for those commands for which the
completion function isn't able to find them out automatically.
The default for this style are the two strings `start' and
`stop'.

complete
This is used by the _expand_alias function when invoked as a
bindable command. If set to `true' and the word on the
command line is not the name of an alias, matching alias names
will be completed.

complete-options
This is used by the completer for cd, chdir and pushd. For
these commands a - is used to introduce a directory stack
entry and completion of these is far more common than
completing options. Hence unless the value of this style is
`true' options will not be completed, even after an initial -.
If it is `true', options will be completed after an initial -
unless there is a preceding -- on the command line.

completer
The strings given as the value of this style provide the names
of the completer functions to use. The available completer
functions are described in the section `Control Functions'
below.

Each string may be either the name of a completer function or
a string of the form `function:name'. In the first case the
completer field of the context will contain the name of the
completer without the leading underscore and with all other
underscores replaced by hyphens. In the second case the
function is the name of the completer to call, but the context
will contain the user-defined name in the completer field of
the context. If the name starts with a hyphen, the string for
the context will be build from the name of the completer
function as in the first case with the name appended to it.
For example:

zstyle ':completion:*' completer _complete _complete:-foo

Here, completion will call the _complete completer twice, once
using `complete' and once using `complete-foo' in the
completer field of the context. Normally, using the same
completer more than once only makes sense when used with the
`functions:name' form, because otherwise the context name will
be the same in all calls to the completer; possible exceptions
to this rule are the _ignored and _prefix completers.

The default value for this style is `_complete _ignored': only
completion will be done, first using the ignored-patterns
style and the $fignore array and then without ignoring
matches.

condition
This style is used by the _list completer function to decide
if insertion of matches should be delayed unconditionally. The
default is `true'.

delimiters
This style is used when adding a delimiter for use with
history modifiers or glob qualifiers that have delimited
arguments. It is an array of preferred delimiters to add.
Non-special characters are preferred as the completion system
may otherwise become confused. The default list is :, +, /,
-, %. The list may be empty to force a delimiter to be typed.

disabled
If this is set to `true', the _expand_alias completer and
bindable command will try to expand disabled aliases, too.
The default is `false'.

domains
A list of names of network domains for completion. If this is
not set, domain names will be taken from the file
/etc/resolv.conf.

environ
The environ style is used when completing for `sudo'. It is
set to an array of `VAR=value' assignments to be exported into
the local environment before the completion for the target
command is invoked.
zstyle ':completion:*:sudo::' environ \
PATH="/sbin:/usr/sbin:$PATH" HOME="/root"

expand This style is used when completing strings consisting of
multiple parts, such as path names.

If one of its values is the string `prefix', the partially
typed word from the line will be expanded as far as possible
even if trailing parts cannot be completed.

If one of its values is the string `suffix', matching names
for components after the first ambiguous one will also be
added. This means that the resulting string is the longest
unambiguous string possible. However, menu completion can be
used to cycle through all matches.

extra-verbose
If set, the completion listing is more verbose at the cost of
a probable decrease in completion speed. Completion
performance will suffer if this style is set to `true'.

fake This style may be set for any completion context. It
specifies additional strings that will always be completed in
that context. The form of each string is `value:description';
the colon and description may be omitted, but any literal
colons in value must be quoted with a backslash. Any
description provided is shown alongside the value in
completion listings.

It is important to use a sufficiently restrictive context when
specifying fake strings. Note that the styles fake-files and
fake-parameters provide additional features when completing
files or parameters.

fake-always
This works identically to the fake style except that the
ignored-patterns style is not applied to it. This makes it
possible to override a set of matches completely by setting
the ignored patterns to `*'.

The following shows a way of supplementing any tag with
arbitrary data, but having it behave for display purposes like
a separate tag. In this example we use the features of the
tag-order style to divide the named-directories tag into two
when performing completion with the standard completer
complete for arguments of cd. The tag
named-directories-normal behaves as normal, but the tag
named-directories-mine contains a fixed set of directories.
This has the effect of adding the match group `extra
directories' with the given completions.

zstyle ':completion::complete:cd:*' tag-order \
'named-directories:-mine:extra\ directories
named-directories:-normal:named\ directories *'
zstyle ':completion::complete:cd:*:named-directories-mine' \
fake-always mydir1 mydir2
zstyle ':completion::complete:cd:*:named-directories-mine' \
ignored-patterns '*'

fake-files
This style is used when completing files and looked up without
a tag. Its values are of the form `dir:names...'. This will
add the names (strings separated by spaces) as possible
matches when completing in the directory dir, even if no such
files really exist. The dir may be a pattern; pattern
characters or colons in dir should be quoted with a backslash
to be treated literally.

This can be useful on systems that support special file
systems whose top-level pathnames can not be listed or
generated with glob patterns (but see accept-exact-dirs for a
more general way of dealing with this problem). It can also
be used for directories for which one does not have read
permission.

The pattern form can be used to add a certain `magic' entry to
all directories on a particular file system.

fake-parameters
This is used by the completion function for parameter names.
Its values are names of parameters that might not yet be set
but should be completed nonetheless. Each name may also be
followed by a colon and a string specifying the type of the
parameter (like `scalar', `array' or `integer'). If the type
is given, the name will only be completed if parameters of
that type are required in the particular context. Names for
which no type is specified will always be completed.

file-list
This style controls whether files completed using the standard
builtin mechanism are to be listed with a long list similar to
ls -l. Note that this feature uses the shell module zsh/stat
for file information; this loads the builtin stat which will
replace any external stat executable. To avoid this the
following code can be included in an initialization file:

zmodload -i zsh/stat
disable stat

The style may either be set to a `true' value (or `all'), or
one of the values `insert' or `list', indicating that files
are to be listed in long format in all circumstances, or when
attempting to insert a file name, or when listing file names
without attempting to insert one.

More generally, the value may be an array of any of the above
values, optionally followed by =num. If num is present it
gives the maximum number of matches for which long listing
style will be used. For example,

zstyle ':completion:*' file-list list=20 insert=10

specifies that long format will be used when listing up to 20
files or inserting a file with up to 10 matches (assuming a
listing is to be shown at all, for example on an ambiguous
completion), else short format will be used.

zstyle -e ':completion:*' file-list \
'(( ${+NUMERIC} )) && reply=(true)'

specifies that long format will be used any time a numeric
argument is supplied, else short format.

file-patterns
This is used by the standard function for completing
filenames, _files. If the style is unset up to three tags are
offered, `globbed-files',`directories' and `all-files',
depending on the types of files expected by the caller of
_files. The first two (`globbed-files' and `directories') are
normally offered together to make it easier to complete files
in sub-directories.

The file-patterns style provides alternatives to the default
tags, which are not used. Its value consists of elements of
the form `pattern:tag'; each string may contain any number of
such specifications separated by spaces.

The pattern is a pattern that is to be used to generate
filenames. Any occurrence of the sequence `%p' is replaced by
any pattern(s) passed by the function calling _files. Colons
in the pattern must be preceded by a backslash to make them
distinguishable from the colon before the tag. If more than
one pattern is needed, the patterns can be given inside
braces, separated by commas.

The tags of all strings in the value will be offered by _files
and used when looking up other styles. Any tags in the same
word will be offered at the same time and before later words.
If no `:tag' is given the `files' tag will be used.

The tag may also be followed by an optional second colon and a
description, which will be used for the `%d' in the value of
the format style (if that is set) instead of the default
description supplied by the completion function. The
inclusion of a description also gives precedence to associated
options such as for completion grouping so it can be used
where files should be separated.

For example, to make the rm command first complete only names
of object files and then the names of all files if there is no
matching object file:

zstyle ':completion:*:*:rm:*:*' file-patterns \
'*.o:object-files' '%p:all-files'

To alter the default behaviour of file completion -- offer
files matching a pattern and directories on the first attempt,
then all files -- to offer only matching files on the first
attempt, then directories, and finally all files:

zstyle ':completion:*' file-patterns \
'%p:globbed-files' '*(-/):directories' '*:all-files'

This works even where there is no special pattern: _files
matches all files using the pattern `*' at the first step and
stops when it sees this pattern. Note also it will never try
a pattern more than once for a single completion attempt.

To separate directories into a separate group from the files
but still complete them at the first attempt, a description
needs to be given. Note that directories need to be
explicitly excluded from the globbed-files because `*' will
match directories. For grouping, it is also necessary to set
the group-name style.

zstyle ':completion:*' file-patterns \
'%p(^-/):globbed-files *(-/):directories:location'

During the execution of completion functions, the
EXTENDED_GLOB option is in effect, so the characters `#', `~'
and `^' have special meanings in the patterns.

file-sort
The standard filename completion function uses this style
without a tag to determine in which order the names should be
listed; menu completion will cycle through them in the same
order. The possible values are: `size' to sort by the size of
the file; `links' to sort by the number of links to the file;
`modification' (or `time' or `date') to sort by the last
modification time; `access' to sort by the last access time;
and `inode' (or `change') to sort by the last inode change
time. If the style is set to any other value, or is unset,
files will be sorted alphabetically by name. If the value
contains the string `reverse', sorting is done in the opposite
order. If the value contains the string `follow', timestamps
are associated with the targets of symbolic links; the default
is to use the timestamps of the links themselves.

file-split-chars
A set of characters that will cause all file completions for
the given context to be split at the point where any of the
characters occurs. A typical use is to set the style to :;
then everything up to and including the last : in the string
so far is ignored when completing files. As this is quite
heavy-handed, it is usually preferable to update completion
functions for contexts where this behaviour is useful.

filter The ldap plugin of email address completion (see
_email_addresses) uses this style to specify the attributes to
match against when filtering entries. So for example, if the
style is set to `sn', matching is done against surnames.
Standard LDAP filtering is used so normal completion matching
is bypassed. If this style is not set, the LDAP plugin is
skipped. You may also need to set the command style to
specify how to connect to your LDAP server.

force-list
This forces a list of completions to be shown at any point
where listing is done, even in cases where the list would
usually be suppressed. For example, normally the list is only
shown if there are at least two different matches. By setting
this style to `always', the list will always be shown, even if
there is only a single match that will immediately be
accepted. The style may also be set to a number. In this
case the list will be shown if there are at least that many
matches, even if they would all insert the same string.

This style is tested for the default tag as well as for each
tag valid for the current completion. Hence the listing can
be forced only for certain types of match.

format If this is set for the descriptions tag, its value is used as
a string to display above matches in completion lists. The
sequence `%d' in this string will be replaced with a short
description of what these matches are. This string may also
contain the output attribute sequences understood by compadd
-X (see zshcompwid(1)).

The style is tested with each tag valid for the current
completion before it is tested for the descriptions tag.
Hence different format strings can be defined for different
types of match.

Note also that some completer functions define additional
`%'-sequences. These are described for the completer
functions that make use of them.

Some completion functions display messages that may be
customised by setting this style for the messages tag. Here,
the `%d' is replaced with a message given by the completion
function.

Finally, the format string is looked up with the warnings tag,
for use when no matches could be generated at all. In this
case the `%d' is replaced with the descriptions for the
matches that were expected separated by spaces. The sequence
`%D' is replaced with the same descriptions separated by
newlines.

It is possible to use printf-style field width specifiers with
`%d' and similar escape sequences. This is handled by the
zformat builtin command from the zsh/zutil module, see
zshmodules(1).

gain-privileges
If set to true, this style enables the use of commands like
sudo or doas to gain extra privileges when retrieving
information for completion. This is only done when a command
such as sudo appears on the command-line. To force the use of,
e.g. sudo or to override any prefix that might be added due to
gain-privileges, the command style can be used with a value
that begins with a hyphen.

glob This is used by the _expand completer. If it is set to `true'
(the default), globbing will be attempted on the words
resulting from a previous substitution (see the substitute
style) or else the original string from the line.

global If this is set to `true' (the default), the _expand_alias
completer and bindable command will try to expand global
aliases.

group-name
The completion system can group different types of matches,
which appear in separate lists. This style can be used to
give the names of groups for particular tags. For example, in
command position the completion system generates names of
builtin and external commands, names of aliases, shell
functions and parameters and reserved words as possible
completions. To have the external commands and shell
functions listed separately:

zstyle ':completion:*:*:-command-:*:commands' \
group-name commands
zstyle ':completion:*:*:-command-:*:functions' \
group-name functions

As a consequence, any match with the same tag will be
displayed in the same group.

If the name given is the empty string the name of the tag for
the matches will be used as the name of the group. So, to
have all different types of matches displayed separately, one
can just set:

zstyle ':completion:*' group-name ''

All matches for which no group name is defined will be put in
a group named -default-.

To display the group name in the output, see the format style
(q.v.) under the descriptions tag.

group-order
This style is additional to the group-name style to specify
the order for display of the groups defined by that style
(compare tag-order, which determines which completions appear
at all). The groups named are shown in the given order; any
other groups are shown in the order defined by the completion
function.

For example, to have names of builtin commands, shell
functions and external commands appear in that order when
completing in command position:

zstyle ':completion:*:*:-command-:*:*' group-order \
builtins functions commands

groups A list of names of UNIX groups. If this is not set, group
names are taken from the YP database or the file `/etc/group'.

hidden If this is set to `true', matches for the given context will
not be listed, although any description for the matches set
with the format style will be shown. If it is set to `all',
not even the description will be displayed.

Note that the matches will still be completed; they are just
not shown in the list. To avoid having matches considered as
possible completions at all, the tag-order style can be
modified as described below.

hosts A list of names of hosts that should be completed. If this is
not set, hostnames are taken from the file `/etc/hosts'.

hosts-ports
This style is used by commands that need or accept hostnames
and network ports. The strings in the value should be of the
form `host:port'. Valid ports are determined by the presence
of hostnames; multiple ports for the same host may appear.

ignore-line
This is tested for each tag valid for the current completion.
If it is set to `true', none of the words that are already on
the line will be considered as possible completions. If it is
set to `current', the word the cursor is on will not be
considered as a possible completion. The value
`current-shown' is similar but only applies if the list of
completions is currently shown on the screen. Finally, if the
style is set to `other', all words on the line except for the
current one will be excluded from the possible completions.

The values `current' and `current-shown' are a bit like the
opposite of the accept-exact style: only strings with missing
characters will be completed.

Note that you almost certainly don't want to set this to
`true' or `other' for a general context such as
`:completion:*'. This is because it would disallow completion
of, for example, options multiple times even if the command in
question accepts the option more than once.

ignore-parents
The style is tested without a tag by the function completing
pathnames in order to determine whether to ignore the names of
directories already mentioned in the current word, or the name
of the current working directory. The value must include one
or both of the following strings:

parent The name of any directory whose path is already
contained in the word on the line is ignored. For
example, when completing after foo/../, the directory
foo will not be considered a valid completion.

pwd The name of the current working directory will not be
completed; hence, for example, completion after ../
will not use the name of the current directory.

In addition, the value may include one or both of:

.. Ignore the specified directories only when the word on
the line contains the substring `../'.

directory
Ignore the specified directories only when names of
directories are completed, not when completing names of
files.

Excluded values act in a similar fashion to values of the
ignored-patterns style, so they can be restored to
consideration by the _ignored completer.

ignored-patterns
A list of patterns; any trial completion matching one of the
patterns will be excluded from consideration. The _ignored
completer can appear in the list of completers to restore the
ignored matches. This is a more configurable version of the
shell parameter $fignore.

Note that the EXTENDED_GLOB option is set during the execution
of completion functions, so the characters `#', `~' and `^'
have special meanings in the patterns.

insert This style is used by the _all_matches completer to decide
whether to insert the list of all matches unconditionally
instead of adding the list as another match.

insert-ids
When completing process IDs, for example as arguments to the
kill and wait builtins the name of a command may be converted
to the appropriate process ID. A problem arises when the
process name typed is not unique. By default (or if this
style is set explicitly to `menu') the name will be converted
immediately to a set of possible IDs, and menu completion will
be started to cycle through them.

If the value of the style is `single', the shell will wait
until the user has typed enough to make the command unique
before converting the name to an ID; attempts at completion
will be unsuccessful until that point. If the value is any
other string, menu completion will be started when the string
typed by the user is longer than the common prefix to the
corresponding IDs.

insert-sections
This style is used with tags of the form `manuals.X' when
completing names of manual pages. If set and the X in the tag
name matches the section number of the page being completed,
the section number is inserted along with the page name. For
example, given

zstyle ':completion:*:manuals.*' insert-sections true

man ssh_<TAB> may be completed to man 5 ssh_config.

The value may also be set to one of `prepend', or `suffix'.
`prepend' behaves the same as `true' as in the above example,
while `suffix' would complete man ssh_<TAB> as man
ssh_config.5.

This is especially useful in conjunction with
separate-sections, as it ensures that the page requested of
man corresponds to the one displayed in the completion listing
when there are multiple pages with the same name (e.g.,
printf(1) and printf(3)).

The default for this style is `false'.

insert-tab
If this is set to `true', the completion system will insert a
TAB character (assuming that was used to start completion)
instead of performing completion when there is no non-blank
character to the left of the cursor. If it is set to `false',
completion will be done even there.

The value may also contain the substrings `pending' or
`pending=val'. In this case, the typed character will be
inserted instead of starting completion when there is
unprocessed input pending. If a val is given, completion will
not be done if there are at least that many characters of
unprocessed input. This is often useful when pasting
characters into a terminal. Note however, that it relies on
the $PENDING special parameter from the zsh/zle module being
set properly which is not guaranteed on all platforms.

The default value of this style is `true' except for
completion within vared builtin command where it is `false'.

insert-unambiguous
This is used by the _match and _approximate completers. These
completers are often used with menu completion since the word
typed may bear little resemblance to the final completion.
However, if this style is `true', the completer will start
menu completion only if it could find no unambiguous initial
string at least as long as the original string typed by the
user.

In the case of the _approximate completer, the completer field
in the context will already have been set to one of
correct-num or approximate-num, where num is the number of
errors that were accepted.

In the case of the _match completer, the style may also be set
to the string `pattern'. Then the pattern on the line is left
unchanged if it does not match unambiguously.

keep-prefix
This style is used by the _expand completer. If it is `true',
the completer will try to keep a prefix containing a tilde or
parameter expansion. Hence, for example, the string `~/f*'
would be expanded to `~/foo' instead of `/home/user/foo'. If
the style is set to `changed' (the default), the prefix will
only be left unchanged if there were other changes between the
expanded words and the original word from the command line.
Any other value forces the prefix to be expanded
unconditionally.

The behaviour of _expand when this style is `true' is to cause
_expand to give up when a single expansion with the restored
prefix is the same as the original; hence any remaining
completers may be called.

known-hosts-files
This style should contain a list of files to search for host
names and (if the use-ip style is set) IP addresses in a
format compatible with ssh known_hosts files. If it is not
set, the files /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts
are used.

last-prompt
This is a more flexible form of the ALWAYS_LAST_PROMPT option.
If it is `true', the completion system will try to return the
cursor to the previous command line after displaying a
completion list. It is tested for all tags valid for the
current completion, then the default tag. The cursor will be
moved back to the previous line if this style is `true' for
all types of match. Note that unlike the ALWAYS_LAST_PROMPT
option this is independent of the numeric argument.

list This style is used by the _history_complete_word bindable
command. If it is set to `true' it has no effect. If it is
set to `false' matches will not be listed. This overrides the
setting of the options controlling listing behaviour, in
particular AUTO_LIST. The context always starts with
`:completion:history-words'.

list-colors
If the zsh/complist module is loaded, this style can be used
to set color specifications. This mechanism replaces the use
of the ZLS_COLORS and ZLS_COLOURS parameters described in the
section `The zsh/complist Module' in zshmodules(1), but the
syntax is the same.

If this style is set for the default tag, the strings in the
value are taken as specifications that are to be used
everywhere. If it is set for other tags, the specifications
are used only for matches of the type described by the tag.
For this to work best, the group-name style must be set to an
empty string.

In addition to setting styles for specific tags, it is also
possible to use group names specified explicitly by the
group-name tag together with the `(group)' syntax allowed by
the ZLS_COLORS and ZLS_COLOURS parameters and simply using the
default tag.

It is possible to use any color specifications already set up
for the GNU version of the ls command:

zstyle ':completion:*:default' list-colors \
${(s.:.)LS_COLORS}

The default colors are the same as for the GNU ls command and
can be obtained by setting the style to an empty string (i.e.
'').

list-dirs-first
This is used by file completion and corresponds to a
particular setting of the file-patterns style. If set, the
default directories to be completed are listed separately from
and before completion for other files.

list-grouped
If this style is `true' (the default), the completion system
will try to make certain completion listings more compact by
grouping matches. For example, options for commands that have
the same description (shown when the verbose style is set to
`true') will appear as a single entry. However, menu
selection can be used to cycle through all the matches.

list-packed
This is tested for each tag valid in the current context as
well as the default tag. If it is set to `true', the
corresponding matches appear in listings as if the LIST_PACKED
option were set. If it is set to `false', they are listed
normally.

list-prompt
If this style is set for the default tag, completion lists
that don't fit on the screen can be scrolled (see the
description of the zsh/complist module in zshmodules(1)). The
value, if not the empty string, will be displayed after every
screenful and the shell will prompt for a key press; if the
style is set to the empty string, a default prompt will be
used.

The value may contain the escape sequences: `%l' or `%L',
which will be replaced by the number of the last line
displayed and the total number of lines; `%m' or `%M', the
number of the last match shown and the total number of
matches; and `%p' and `%P', `Top' when at the beginning of the
list, `Bottom' when at the end and the position shown as a
percentage of the total length otherwise. In each case the
form with the uppercase letter will be replaced by a string of
fixed width, padded to the right with spaces, while the
lowercase form will be replaced by a variable width string.
As in other prompt strings, the escape sequences `%S', `%s',
`%B', `%b', `%U', `%u' for entering and leaving the display
modes standout, bold and underline, and `%F', `%f', `%K', `%k'
for changing the foreground background colour, are also
available, as is the form `%{...%}' for enclosing escape
sequences which display with zero (or, with a numeric
argument, some other) width.

After deleting this prompt the variable LISTPROMPT should be
unset for the removal to take effect.

list-rows-first
This style is tested in the same way as the list-packed style
and determines whether matches are to be listed in a
rows-first fashion as if the LIST_ROWS_FIRST option were set.

list-separator
The value of this style is used in completion listing to
separate the string to complete from a description when
possible (e.g. when completing options). It defaults to `--'
(two hyphens).

list-suffixes
This style is used by the function that completes filenames.
If it is `true', and completion is attempted on a string
containing multiple partially typed pathname components, all
ambiguous components will be shown. Otherwise, completion
stops at the first ambiguous component.

local This is for use with functions that complete URLs for which
the corresponding files are available directly from the file
system. Its value should consist of three strings: a
hostname, the path to the default web pages for the server,
and the directory name used by a user placing web pages within
their home area.

For example:

zstyle ':completion:*' local toast \
/var/http/public/toast public_html

Completion after `http://toast/stuff/' will look for files in
the directory /var/http/public/toast/stuff, while completion
after `http://toast/~yousir/' will look for files in the
directory ~yousir/public_html.

mail-directory
If set, zsh will assume that mailbox files can be found in the
directory specified. It defaults to `~/Mail'.

match-original
This is used by the _match completer. If it is set to only,
_match will try to generate matches without inserting a `*' at
the cursor position. If set to any other non-empty value, it
will first try to generate matches without inserting the `*'
and if that yields no matches, it will try again with the `*'
inserted. If it is unset or set to the empty string, matching
will only be performed with the `*' inserted.

matcher
This style is tested separately for each tag valid in the
current context. Its value is placed before any match
specifications given by the matcher-list style so can override
them via the use of an x: specification. The value should be
in the form described in the section `Completion Matching
Control' in zshcompwid(1). For examples of this, see the
description of the tag-order style.

For notes comparing the use of this and the matcher-list
style, see under the description of the tag-order style.

matcher-list
This style can be set to a list of match specifications that
are to be applied everywhere. Match specifications are
described in the section `Completion Matching Control' in
zshcompwid(1). The completion system will try them one after
another for each completer selected. For example, to try
first simple completion and, if that generates no matches,
case-insensitive completion:

zstyle ':completion:*' matcher-list '' 'm:{a-zA-Z}={A-Za-z}'

By default each specification replaces the previous one;
however, if a specification is prefixed with +, it is added to
the existing list. Hence it is possible to create
increasingly general specifications without repetition:

zstyle ':completion:*' matcher-list \
'' '+m:{a-z}={A-Z}' '+m:{A-Z}={a-z}'

It is possible to create match specifications valid for
particular completers by using the third field of the context.
This applies only to completers that override the global
matcher-list, which as of this writing includes only _prefix
and _ignored. For example, to use the completers _complete
and _prefix but allow case-insensitive completion only with
_complete:

zstyle ':completion:*' completer _complete _prefix
zstyle ':completion:*:complete:*:*:*' matcher-list \
'' 'm:{a-zA-Z}={A-Za-z}'

User-defined names, as explained for the completer style, are
available. This makes it possible to try the same completer
more than once with different match specifications each time.
For example, to try normal completion without a match
specification, then normal completion with case-insensitive
matching, then correction, and finally partial-word
completion:

zstyle ':completion:*' completer \
_complete _correct _complete:foo
zstyle ':completion:*:complete:*:*:*' matcher-list \
'' 'm:{a-zA-Z}={A-Za-z}'
zstyle ':completion:*:foo:*:*:*' matcher-list \
'm:{a-zA-Z}={A-Za-z} r:|[-_./]=* r:|=*'

If the style is unset in any context no match specification is
applied. Note also that some completers such as _correct and
_approximate do not use the match specifications at all,
though these completers will only ever be called once even if
the matcher-list contains more than one element.

Where multiple specifications are useful, note that the entire
completion is done for each element of matcher-list, which can
quickly reduce the shell's performance. As a rough rule of
thumb, one to three strings will give acceptable performance.
On the other hand, putting multiple space-separated values
into the same string does not have an appreciable impact on
performance.

If there is no current matcher or it is empty, and the option
NO_CASE_GLOB is in effect, the matching for files is performed
case-insensitively in any case. However, any matcher must
explicitly specify case-insensitive matching if that is
required.

For notes comparing the use of this and the matcher style, see
under the description of the tag-order style.

max-errors
This is used by the _approximate and _correct completer
functions to determine the maximum number of errors to allow.
The completer will try to generate completions by first
allowing one error, then two errors, and so on, until either a
match or matches were found or the maximum number of errors
given by this style has been reached.

If the value for this style contains the string `numeric', the
completer function will take any numeric argument as the
maximum number of errors allowed. For example, with

zstyle ':completion:*:approximate:::' max-errors 2 numeric

two errors are allowed if no numeric argument is given, but
with a numeric argument of six (as in `ESC-6 TAB'), up to six
errors are accepted. Hence with a value of `0 numeric', no
correcting completion will be attempted unless a numeric
argument is given.

If the value contains the string `not-numeric', the completer
will not try to generate corrected completions when given a
numeric argument, so in this case the number given should be
greater than zero. For example, `2 not-numeric' specifies
that correcting completion with two errors will usually be
performed, but if a numeric argument is given, correcting
completion will not be performed.

The default value for this style is `2 numeric'.

max-matches-width
This style is used to determine the trade off between the
width of the display used for matches and the width used for
their descriptions when the verbose style is in effect. The
value gives the number of display columns to reserve for the
matches. The default is half the width of the screen.

This has the most impact when several matches have the same
description and so will be grouped together. Increasing the
style will allow more matches to be grouped together;
decreasing it will allow more of the description to be
visible.

menu If this is `true' in the context of any of the tags defined
for the current completion menu completion will be used. The
value for a specific tag will take precedence over that for
the `default' tag.

If none of the values found in this way is `true' but at least
one is set to `auto', the shell behaves as if the AUTO_MENU
option is set.

If one of the values is explicitly set to `false', menu
completion will be explicitly turned off, overriding the
MENU_COMPLETE option and other settings.

In the form `yes=num', where `yes' may be any of the `true'
values (`yes', `true', `on' and `1'), menu completion will be
turned on if there are at least num matches. In the form
`yes=long', menu completion will be turned on if the list does
not fit on the screen. This does not activate menu completion
if the widget normally only lists completions, but menu
completion can be activated in that case with the value
`yes=long-list' (Typically, the value `select=long-list'
described later is more useful as it provides control over
scrolling.)

Similarly, with any of the `false' values (as in `no=10'),
menu completion will not be used if there are num or more
matches.

The value of this widget also controls menu selection, as
implemented by the zsh/complist module. The following values
may appear either alongside or instead of the values above.

If the value contains the string `select', menu selection will
be started unconditionally.

In the form `select=num', menu selection will only be started
if there are at least num matches. If the values for more
than one tag provide a number, the smallest number is taken.

Menu selection can be turned off explicitly by defining a
value containing the string`no-select'.

It is also possible to start menu selection only if the list
of matches does not fit on the screen by using the value
`select=long'. To start menu selection even if the current
widget only performs listing, use the value
`select=long-list'.

To turn on menu completion or menu selection when there are a
certain number of matches or the list of matches does not fit
on the screen, both of `yes=' and `select=' may be given
twice, once with a number and once with `long' or `long-list'.

Finally, it is possible to activate two special modes of menu
selection. The word `interactive' in the value causes
interactive mode to be entered immediately when menu selection
is started; see the description of the zsh/complist module in
zshmodules(1) for a description of interactive mode.
Including the string `search' does the same for incremental
search mode. To select backward incremental search, include
the string `search-backward'.

muttrc If set, gives the location of the mutt configuration file. It
defaults to `~/.muttrc'.

numbers
This is used with the jobs tag. If it is `true', the shell
will complete job numbers instead of the shortest unambiguous
prefix of the job command text. If the value is a number, job
numbers will only be used if that many words from the job
descriptions are required to resolve ambiguities. For
example, if the value is `1', strings will only be used if all
jobs differ in the first word on their command lines.

old-list
This is used by the _oldlist completer. If it is set to
`always', then standard widgets which perform listing will
retain the current list of matches, however they were
generated; this can be turned off explicitly with the value
`never', giving the behaviour without the _oldlist completer.
If the style is unset, or any other value, then the existing
list of completions is displayed if it is not already;
otherwise, the standard completion list is generated; this is
the default behaviour of _oldlist. However, if there is an
old list and this style contains the name of the completer
function that generated the list, then the old list will be
used even if it was generated by a widget which does not do
listing.

For example, suppose you type ^Xc to use the _correct_word
widget, which generates a list of corrections for the word
under the cursor. Usually, typing ^D would generate a
standard list of completions for the word on the command line,
and show that. With _oldlist, it will instead show the list
of corrections already generated.

As another example consider the _match completer: with the
insert-unambiguous style set to `true' it inserts only a
common prefix string, if there is any. However, this may
remove parts of the original pattern, so that further
completion could produce more matches than on the first
attempt. By using the _oldlist completer and setting this
style to _match, the list of matches generated on the first
attempt will be used again.

old-matches
This is used by the _all_matches completer to decide if an old
list of matches should be used if one exists. This is
selected by one of the `true' values or by the string `only'.
If the value is `only', _all_matches will only use an old list
and won't have any effect on the list of matches currently
being generated.

If this style is set it is generally unwise to call the
_all_matches completer unconditionally. One possible use is
for either this style or the completer style to be defined
with the -e option to zstyle to make the style conditional.

old-menu
This is used by the _oldlist completer. It controls how menu
completion behaves when a completion has already been inserted
and the user types a standard completion key such as TAB. The
default behaviour of _oldlist is that menu completion always
continues with the existing list of completions. If this
style is set to `false', however, a new completion is started
if the old list was generated by a different completion
command; this is the behaviour without the _oldlist completer.

For example, suppose you type ^Xc to generate a list of
corrections, and menu completion is started in one of the
usual ways. Usually, or with this style set to `false',
typing TAB at this point would start trying to complete the
line as it now appears. With _oldlist, it instead continues
to cycle through the list of corrections.

original
This is used by the _approximate and _correct completers to
decide if the original string should be added as a possible
completion. Normally, this is done only if there are at least
two possible corrections, but if this style is set to `true',
it is always added. Note that the style will be examined with
the completer field in the context name set to correct-num or
approximate-num, where num is the number of errors that were
accepted.

packageset
This style is used when completing arguments of the Debian
`dpkg' program. It contains an override for the default
package set for a given context. For example,

zstyle ':completion:*:complete:dpkg:option--status-1:*' \
packageset avail

causes available packages, rather than only installed
packages, to be completed for `dpkg --status'.

path The function that completes color names uses this style with
the colors tag. The value should be the pathname of a file
containing color names in the format of an X11 rgb.txt file.
If the style is not set but this file is found in one of
various standard locations it will be used as the default.

path-completion
This is used by filename completion. By default, filename
completion examines all components of a path to see if there
are completions of that component. For example, /u/b/z can be
completed to /usr/bin/zsh. Explicitly setting this style to
`false' inhibits this behaviour for path components up to the
/ before the cursor; this overrides the setting of
accept-exact-dirs.

Even with the style set to `false', it is still possible to
complete multiple paths by setting the option COMPLETE_IN_WORD
and moving the cursor back to the first component in the path
to be completed. For example, /u/b/z can be completed to
/usr/bin/zsh if the cursor is after the /u.

pine-directory
If set, specifies the directory containing PINE mailbox files.
There is no default, since recursively searching this
directory is inconvenient for anyone who doesn't use PINE.

ports A list of Internet service names (network ports) to complete.
If this is not set, service names are taken from the file
`/etc/services'.

prefix-hidden
This is used for certain completions which share a common
prefix, for example command options beginning with dashes. If
it is `true', the prefix will not be shown in the list of
matches.

The default value for this style is `false'.

prefix-needed
This style is also relevant for matches with a common prefix.
If it is set to `true' this common prefix must be typed by the
user to generate the matches.

The style is applicable to the options, signals, jobs,
functions, and parameters completion tags.

For command options, this means that the initial `-', `+', or
`--' must be typed explicitly before option names will be
completed.

For signals, an initial `-' is required before signal names
will be completed.

For jobs, an initial `%' is required before job names will be
completed.

For function and parameter names, an initial `_' or `.' is
required before function or parameter names starting with
those characters will be completed.

The default value for this style is `false' for function and
parameter completions, and `true' otherwise.

preserve-prefix
This style is used when completing path names. Its value
should be a pattern matching an initial prefix of the word to
complete that should be left unchanged under all
circumstances. For example, on some Unices an initial `//'
(double slash) has a special meaning; setting this style to
the string `//' will preserve it. As another example, setting
this style to `?:/' under Cygwin would allow completion after
`a:/...' and so on.

range This is used by the _history completer and the
_history_complete_word bindable command to decide which words
should be completed.

If it is a single number, only the last N words from the
history will be completed.

If it is a range of the form `max:slice', the last slice words
will be completed; then if that yields no matches, the slice
words before those will be tried and so on. This process
stops either when at least one match has been found, or max
words have been tried.

The default is to complete all words from the history at once.

recursive-files
If this style is set, its value is an array of patterns to be
tested against `$PWD/': note the trailing slash, which allows
directories in the pattern to be delimited unambiguously by
including slashes on both sides. If an ordinary file
completion fails and the word on the command line does not yet
have a directory part to its name, the style is retrieved
using the same tag as for the completion just attempted, then
the elements tested against $PWD/ in turn. If one matches,
then the shell reattempts completion by prepending the word on
the command line with each directory in the expansion of
**/*(/) in turn. Typically the elements of the style will be
set to restrict the number of directories beneath the current
one to a manageable number, for example `*/.git/*'.

For example,

zstyle ':completion:*' recursive-files '*/zsh/*'

If the current directory is /home/pws/zsh/Src, then
zle_tr<TAB> can be completed to Zle/zle_tricky.c.

regular
This style is used by the _expand_alias completer and bindable
command. If set to `true' (the default), regular aliases will
be expanded but only in command position. If it is set to
`false', regular aliases will never be expanded. If it is
set to `always', regular aliases will be expanded even if not
in command position.

rehash If this is set when completing external commands, the internal
list (hash) of commands will be updated for each search by
issuing the rehash command. There is a speed penalty for this
which is only likely to be noticeable when directories in the
path have slow file access.

remote-access
If set to `false', certain commands will be prevented from
making Internet connections to retrieve remote information.
This includes the completion for the CVS command.

It is not always possible to know if connections are in fact
to a remote site, so some may be prevented unnecessarily.

remove-all-dups
The _history_complete_word bindable command and the _history
completer use this to decide if all duplicate matches should
be removed, rather than just consecutive duplicates.

select-prompt
If this is set for the default tag, its value will be
displayed during menu selection (see the menu style above)
when the completion list does not fit on the screen as a
whole. The same escapes as for the list-prompt style are
understood, except that the numbers refer to the match or line
the mark is on. A default prompt is used when the value is
the empty string.

select-scroll
This style is tested for the default tag and determines how a
completion list is scrolled during a menu selection (see the
menu style above) when the completion list does not fit on the
screen as a whole. If the value is `0' (zero), the list is
scrolled by half-screenfuls; if it is a positive integer, the
list is scrolled by the given number of lines; if it is a
negative number, the list is scrolled by a screenful minus the
absolute value of the given number of lines. The default is
to scroll by single lines.

separate-sections
This style is used with the manuals tag when completing names
of manual pages. If it is `true', entries for different
sections are added separately using tag names of the form
`manuals.X', where X is the section number. When the
group-name style is also in effect, pages from different
sections will appear separately. This style is also used
similarly with the words style when completing words for the
dict command. It allows words from different dictionary
databases to be added separately. See also insert-sections.

The default for this style is `false'.

show-ambiguity
If the zsh/complist module is loaded, this style can be used
to highlight the first ambiguous character in completion
lists. The value is either a color indication such as those
supported by the list-colors style or, with a value of `true',
a default of underlining is selected. The highlighting is only
applied if the completion display strings correspond to the
actual matches.

show-completer
Tested whenever a new completer is tried. If it is `true',
the completion system outputs a progress message in the
listing area showing what completer is being tried. The
message will be overwritten by any output when completions are
found and is removed after completion is finished.

single-ignored
This is used by the _ignored completer when there is only one
match. If its value is `show', the single match will be
displayed but not inserted. If the value is `menu', then the
single match and the original string are both added as matches
and menu completion is started, making it easy to select
either of them.

sort This allows the standard ordering of matches to be overridden.

If its value is `true' or `false', sorting is enabled or
disabled. Additionally the values associated with the `-o'
option to compadd can also be listed: match, nosort, numeric,
reverse. If it is not set for the context, the standard
behaviour of the calling widget is used.

The style is tested first against the full context including
the tag, and if that fails to produce a value against the
context without the tag.

In many cases where a calling widget explicitly selects a
particular ordering in lieu of the default, a value of `true'
is not honoured. An example of where this is not the case is
for command history where the default of sorting matches
chronologically may be overridden by setting the style to
`true'.

In the _expand completer, if it is set to `true', the
expansions generated will always be sorted. If it is set to
`menu', then the expansions are only sorted when they are
offered as single strings but not in the string containing all
possible expansions.

special-dirs
Normally, the completion code will not produce the directory
names `.' and `..' as possible completions. If this style is
set to `true', it will add both `.' and `..' as possible
completions; if it is set to `..', only `..' will be added.

The following example sets special-dirs to `..' when the
current prefix is empty, is a single `.', or consists only of
a path beginning with `../'. Otherwise the value is `false'.

zstyle -e ':completion:*' special-dirs \
'[[ $PREFIX = (../)#(|.|..) ]] && reply=(..)'

squeeze-slashes
If set to `true', sequences of slashes in filename paths (for
example in `foo//bar') will be treated as a single slash.
This is the usual behaviour of UNIX paths. However, by
default the file completion function behaves as if there were
a `*' between the slashes.

stop If set to `true', the _history_complete_word bindable command
will stop once when reaching the beginning or end of the
history. Invoking _history_complete_word will then wrap
around to the opposite end of the history. If this style is
set to `false' (the default), _history_complete_word will loop
immediately as in a menu completion.

strip-comments
If set to `true', this style causes non-essential comment text
to be removed from completion matches. Currently it is only
used when completing e-mail addresses where it removes any
display name from the addresses, cutting them down to plain
user@host form.

subst-globs-only
This is used by the _expand completer. If it is set to
`true', the expansion will only be used if it resulted from
globbing; hence, if expansions resulted from the use of the
substitute style described below, but these were not further
changed by globbing, the expansions will be rejected.

The default for this style is `false'.

substitute
This boolean style controls whether the _expand completer will
first try to expand all substitutions in the string (such as
`$(...)' and `${...}').

The default is `true'.

suffix This is used by the _expand completer if the word starts with
a tilde or contains a parameter expansion. If it is set to
`true', the word will only be expanded if it doesn't have a
suffix, i.e. if it is something like `~foo' or `$foo' rather
than `~foo/' or `$foo/bar', unless that suffix itself contains
characters eligible for expansion. The default for this style
is `true'.

tag-order
This provides a mechanism for sorting how the tags available
in a particular context will be used.

The values for the style are sets of space-separated lists of
tags. The tags in each value will be tried at the same time;
if no match is found, the next value is used. (See the
file-patterns style for an exception to this behavior.)

For example:

zstyle ':completion:*:complete:-command-:*:*' tag-order \
'commands functions'

specifies that completion in command position first offers
external commands and shell functions. Remaining tags will be
tried if no completions are found.

In addition to tag names, each string in the value may take
one of the following forms:

- If any value consists of only a hyphen, then only the
tags specified in the other values are generated.
Normally all tags not explicitly selected are tried
last if the specified tags fail to generate any
matches. This means that a single value consisting
only of a single hyphen turns off completion.

! tags...
A string starting with an exclamation mark specifies
names of tags that are not to be used. The effect is
the same as if all other possible tags for the context
had been listed.

tag:label ...
Here, tag is one of the standard tags and label is an
arbitrary name. Matches are generated as normal but
the name label is used in contexts instead of tag.
This is not useful in words starting with !.

If the label starts with a hyphen, the tag is prepended
to the label to form the name used for lookup. This
can be used to make the completion system try a certain
tag more than once, supplying different style settings
for each attempt; see below for an example.

tag:label:description
As before, but description will replace the `%d' in the
value of the format style instead of the default
description supplied by the completion function.
Spaces in the description must be quoted with a
backslash. A `%d' appearing in description is replaced
with the description given by the completion function.

In any of the forms above the tag may be a pattern or several
patterns in the form `{pat1,pat2...}'. In this case all
matching tags will be used except for any given explicitly in
the same string.

One use of these features is to try one tag more than once,
setting other styles differently on each attempt, but still to
use all the other tags without having to repeat them all. For
example, to make completion of function names in command
position ignore all the completion functions starting with an
underscore the first time completion is tried:

zstyle ':completion:*:*:-command-:*:*' tag-order \
'functions:-non-comp *' functions
zstyle ':completion:*:functions-non-comp' \
ignored-patterns '_*'

On the first attempt, all tags will be offered but the
functions tag will be replaced by functions-non-comp. The
ignored-patterns style is set for this tag to exclude
functions starting with an underscore. If there are no
matches, the second value of the tag-order style is used which
completes functions using the default tag, this time
presumably including all function names.

The matches for one tag can be split into different groups.
For example:

zstyle ':completion:*' tag-order \
'options:-long:long\ options
options:-short:short\ options
options:-single-letter:single\ letter\ options'
zstyle ':completion:*:options-long' \
ignored-patterns '[-+](|-|[^-]*)'
zstyle ':completion:*:options-short' \
ignored-patterns '--*' '[-+]?'
zstyle ':completion:*:options-single-letter' \
ignored-patterns '???*'

With the group-names style set, options beginning with `--',
options beginning with a single `-' or `+' but containing
multiple characters, and single-letter options will be
displayed in separate groups with different descriptions.

Another use of patterns is to try multiple match
specifications one after another. The matcher-list style
offers something similar, but it is tested very early in the
completion system and hence can't be set for single commands
nor for more specific contexts. Here is how to try normal
completion without any match specification and, if that
generates no matches, try again with case-insensitive
matching, restricting the effect to arguments of the command
foo:

zstyle ':completion:*:*:foo:*:*' tag-order '*' '*:-case'
zstyle ':completion:*-case' matcher 'm:{a-z}={A-Z}'

First, all the tags offered when completing after foo are
tried using the normal tag name. If that generates no
matches, the second value of tag-order is used, which tries
all tags again except that this time each has -case appended
to its name for lookup of styles. Hence this time the value
for the matcher style from the second call to zstyle in the
example is used to make completion case-insensitive.

It is possible to use the -e option of the zstyle builtin
command to specify conditions for the use of particular tags.
For example:

zstyle -e '*:-command-:*' tag-order '
if [[ -n $PREFIX$SUFFIX ]]; then
reply=( )
else
reply=( - )
fi'

Completion in command position will be attempted only if the
string typed so far is not empty. This is tested using the
PREFIX special parameter; see zshcompwid for a description of
parameters which are special inside completion widgets.
Setting reply to an empty array provides the default behaviour
of trying all tags at once; setting it to an array containing
only a hyphen disables the use of all tags and hence of all
completions.

If no tag-order style has been defined for a context, the
strings `(|*-)argument-* (|*-)option-* values' and `options'
plus all tags offered by the completion function will be used
to provide a sensible default behavior that causes arguments
(whether normal command arguments or arguments of options) to
be completed before option names for most commands.

urls This is used together with the urls tag by functions
completing URLs.

If the value consists of more than one string, or if the only
string does not name a file or directory, the strings are used
as the URLs to complete.

If the value contains only one string which is the name of a
normal file the URLs are taken from that file (where the URLs
may be separated by white space or newlines).

Finally, if the only string in the value names a directory,
the directory hierarchy rooted at this directory gives the
completions. The top level directory should be the file
access method, such as `http', `ftp', `bookmark' and so on.
In many cases the next level of directories will be a
filename. The directory hierarchy can descend as deep as
necessary.

For example,

zstyle ':completion:*' urls ~/.urls
mkdir -p ~/.urls/ftp/ftp.zsh.org/pub


allows completion of all the components of the URL
ftp://ftp.zsh.org/pub after suitable commands such as
`netscape' or `lynx'. Note, however, that access methods and
files are completed separately, so if the hosts style is set
hosts can be completed without reference to the urls style.

See the description in the function _urls itself for more
information (e.g. `more $^fpath/_urls(N)').

use-cache
If this is set, the completion caching layer is activated for
any completions which use it (via the _store_cache,
_retrieve_cache, and _cache_invalid functions). The directory
containing the cache files can be changed with the cache-path
style.

use-compctl
If this style is set to a string not equal to false, 0, no,
and off, the completion system may use any completion
specifications defined with the compctl builtin command. If
the style is unset, this is done only if the zsh/compctl
module is loaded. The string may also contain the substring
`first' to use completions defined with `compctl -T', and the
substring `default' to use the completion defined with
`compctl -D'.

Note that this is only intended to smooth the transition from
compctl to the new completion system and may disappear in the
future.

Note also that the definitions from compctl will only be used
if there is no specific completion function for the command in
question. For example, if there is a function _foo to
complete arguments to the command foo, compctl will never be
invoked for foo. However, the compctl version will be tried
if foo only uses default completion.

use-ip By default, the function _hosts that completes host names
strips IP addresses from entries read from host databases such
as NIS and ssh files. If this style is `true', the
corresponding IP addresses can be completed as well. This
style is not use in any context where the hosts style is set;
note also it must be set before the cache of host names is
generated (typically the first completion attempt).

users This may be set to a list of usernames to be completed. If it
is not set all usernames will be completed. Note that if it
is set only that list of users will be completed; this is
because on some systems querying all users can take a
prohibitive amount of time.

users-hosts
The values of this style should be of the form `user@host' or
`user:host'. It is used for commands that need pairs of user-
and hostnames. These commands will complete usernames from
this style (only), and will restrict subsequent hostname
completion to hosts paired with that user in one of the values
of the style.

It is possible to group values for sets of commands which
allow a remote login, such as rlogin and ssh, by using the
my-accounts tag. Similarly, values for sets of commands which
usually refer to the accounts of other people, such as talk
and finger, can be grouped by using the other-accounts tag.
More ambivalent commands may use the accounts tag.

users-hosts-ports
Like users-hosts but used for commands like telnet and
containing strings of the form `user@host:port'.

verbose
If set, as it is by default, the completion listing is more
verbose. In particular many commands show descriptions for
options if this style is `true'.

word This is used by the _list completer, which prevents the
insertion of completions until a second completion attempt
when the line has not changed. The normal way of finding out
if the line has changed is to compare its entire contents
between the two occasions. If this style is `true', the
comparison is instead performed only on the current word.
Hence if completion is performed on another word with the same
contents, completion will not be delayed.

CONTROL FUNCTIONS

The initialization script compinit redefines all the widgets which
perform completion to call the supplied widget function
_main_complete. This function acts as a wrapper calling the
so-called `completer' functions that generate matches. If
_main_complete is called with arguments, these are taken as the names
of completer functions to be called in the order given. If no
arguments are given, the set of functions to try is taken from the
completer style. For example, to use normal completion and
correction if that doesn't generate any matches:

zstyle ':completion:*' completer _complete _correct

after calling compinit. The default value for this style is
`_complete _ignored', i.e. normally only ordinary completion is
tried, first with the effect of the ignored-patterns style and then
without it. The _main_complete function uses the return status of
the completer functions to decide if other completers should be
called. If the return status is zero, no other completers are tried
and the _main_complete function returns.

If the first argument to _main_complete is a single hyphen, the
arguments will not be taken as names of completers. Instead, the
second argument gives a name to use in the completer field of the
context and the other arguments give a command name and arguments to
call to generate the matches.

The following completer functions are contained in the distribution,
although users may write their own. Note that in contexts the
leading underscore is stripped, for example basic completion is
performed in the context `:completion::complete:...'.

_all_matches
This completer can be used to add a string consisting of all
other matches. As it influences later completers it must
appear as the first completer in the list. The list of all
matches is affected by the avoid-completer and old-matches
styles described above.

It may be useful to use the _generic function described below
to bind _all_matches to its own keystroke, for example:

zle -C all-matches complete-word _generic
bindkey '^Xa' all-matches
zstyle ':completion:all-matches:*' old-matches only
zstyle ':completion:all-matches::::' completer _all_matches

Note that this does not generate completions by itself: first
use any of the standard ways of generating a list of
completions, then use ^Xa to show all matches. It is possible
instead to add a standard completer to the list and request
that the list of all matches should be directly inserted:

zstyle ':completion:all-matches::::' completer \
_all_matches _complete
zstyle ':completion:all-matches:*' insert true

In this case the old-matches style should not be set.

_approximate
This is similar to the basic _complete completer but allows
the completions to undergo corrections. The maximum number of
errors can be specified by the max-errors style; see the
description of approximate matching in zshexpn(1) for how
errors are counted. Normally this completer will only be
tried after the normal _complete completer:

zstyle ':completion:*' completer _complete _approximate

This will give correcting completion if and only if normal
completion yields no possible completions. When corrected
completions are found, the completer will normally start menu
completion allowing you to cycle through these strings.

This completer uses the tags corrections and original when
generating the possible corrections and the original string.
The format style for the former may contain the additional
sequences `%e' and `%o' which will be replaced by the number
of errors accepted to generate the corrections and the
original string, respectively.

The completer progressively increases the number of errors
allowed up to the limit by the max-errors style, hence if a
completion is found with one error, no completions with two
errors will be shown, and so on. It modifies the completer
name in the context to indicate the number of errors being
tried: on the first try the completer field contains
`approximate-1', on the second try `approximate-2', and so on.

When _approximate is called from another function, the number
of errors to accept may be passed with the -a option. The
argument is in the same format as the max-errors style, all in
one string.

Note that this completer (and the _correct completer mentioned
below) can be quite expensive to call, especially when a large
number of errors are allowed. One way to avoid this is to set
up the completer style using the -e option to zstyle so that
some completers are only used when completion is attempted a
second time on the same string, e.g.:

zstyle -e ':completion:*' completer '
if [[ $_last_try != "$HISTNO$BUFFER$CURSOR" ]]; then
_last_try="$HISTNO$BUFFER$CURSOR"
reply=(_complete _match _prefix)
else
reply=(_ignored _correct _approximate)
fi'

This uses the HISTNO parameter and the BUFFER and CURSOR
special parameters that are available inside zle and
completion widgets to find out if the command line hasn't
changed since the last time completion was tried. Only then
are the _ignored, _correct and _approximate completers called.

_canonical_paths [ -A var ] [ -N ] [ -MJV12nfX ] tag descr [ paths
... ] This completion function completes all paths given to it, and
also tries to offer completions which point to the same file
as one of the paths given (relative path when an absolute path
is given, and vice versa; when ..'s are present in the word to
be completed; and some paths got from symlinks).

-A, if specified, takes the paths from the array variable
specified. Paths can also be specified on the command line as
shown above. -N, if specified, prevents canonicalizing the
paths given before using them for completion, in case they are
already so. The options -M, -J, -V, -1, -2, -n, -F, -X are
passed to compadd.

See _description for a description of tag and descr.

_cmdambivalent
Completes the remaining positional arguments as an external
command. The external command and its arguments are completed
as separate arguments (in a manner appropriate for completing
/usr/bin/env) if there are two or more remaining positional
arguments on the command line, and as a quoted command string
(in the manner of system(...)) otherwise. See also _cmdstring
and _precommand.

This function takes no arguments.

_cmdstring
Completes an external command as a single argument, as for
system(...).

_complete
This completer generates all possible completions in a
context-sensitive manner, i.e. using the settings defined with
the compdef function explained above and the current settings
of all special parameters. This gives the normal completion
behaviour.

To complete arguments of commands, _complete uses the utility
function _normal, which is in turn responsible for finding the
particular function; it is described below. Various contexts
of the form -context- are handled specifically. These are all
mentioned above as possible arguments to the #compdef tag.

Before trying to find a function for a specific context,
_complete checks if the parameter `compcontext' is set.
Setting `compcontext' allows the usual completion dispatching
to be overridden which is useful in places such as a function
that uses vared for input. If it is set to an array, the
elements are taken to be the possible matches which will be
completed using the tag `values' and the description `value'.
If it is set to an associative array, the keys are used as the
possible completions and the values (if non-empty) are used as
descriptions for the matches. If `compcontext' is set to a
string containing colons, it should be of the form
`tag:descr:action'. In this case the tag and descr give the
tag and description to use and the action indicates what
should be completed in one of the forms accepted by the
_arguments utility function described below.

Finally, if `compcontext' is set to a string without colons,
the value is taken as the name of the context to use and the
function defined for that context will be called. For this
purpose, there is a special context named -command-line- that
completes whole command lines (commands and their arguments).
This is not used by the completion system itself but is
nonetheless handled when explicitly called.

_correct
Generate corrections, but not completions, for the current
word; this is similar to _approximate but will not allow any
number of extra characters at the cursor as that completer
does. The effect is similar to spell-checking. It is based
on _approximate, but the completer field in the context name
is correct.

For example, with:

zstyle ':completion:::::' completer \
_complete _correct _approximate
zstyle ':completion:*:correct:::' max-errors 2 not-numeric
zstyle ':completion:*:approximate:::' max-errors 3 numeric

correction will accept up to two errors. If a numeric
argument is given, correction will not be performed, but
correcting completion will be, and will accept as many errors
as given by the numeric argument. Without a numeric argument,
first correction and then correcting completion will be tried,
with the first one accepting two errors and the second one
accepting three errors.

When _correct is called as a function, the number of errors to
accept may be given following the -a option. The argument is
in the same form a values to the accept style, all in one
string.

This completer function is intended to be used without the
_approximate completer or, as in the example, just before it.
Using it after the _approximate completer is useless since
_approximate will at least generate the corrected strings
generated by the _correct completer -- and probably more.

_expand
This completer function does not really perform completion,
but instead checks if the word on the command line is eligible
for expansion and, if it is, gives detailed control over how
this expansion is done. For this to happen, the completion
system needs to be invoked with complete-word, not
expand-or-complete (the default binding for TAB), as otherwise
the string will be expanded by the shell's internal mechanism
before the completion system is started. Note also this
completer should be called before the _complete completer
function.

The tags used when generating expansions are all-expansions
for the string containing all possible expansions, expansions
when adding the possible expansions as single matches and
original when adding the original string from the line. The
order in which these strings are generated, if at all, can be
controlled by the group-order and tag-order styles, as usual.

The format string for all-expansions and for expansions may
contain the sequence `%o' which will be replaced by the
original string from the line.

The kind of expansion to be tried is controlled by the
substitute, glob and subst-globs-only styles.

It is also possible to call _expand as a function, in which
case the different modes may be selected with options: -s for
substitute, -g for glob and -o for subst-globs-only.

_expand_alias
If the word the cursor is on is an alias, it is expanded and
no other completers are called. The types of aliases which
are to be expanded can be controlled with the styles regular,
global and disabled.

This function is also a bindable command, see the section
`Bindable Commands' below.

_extensions
If the cursor follows the string `*.', filename extensions are
completed. The extensions are taken from files in current
directory or a directory specified at the beginning of the
current word. For exact matches, completion continues to allow
other completers such as _expand to expand the pattern. The
standard add-space and prefix-hidden styles are observed.

_external_pwds
Completes current directories of other zsh processes belonging
to the current user.

This is intended to be used via _generic, bound to a custom
key combination. Note that pattern matching is enabled so
matching is performed similar to how it works with the _match
completer.

_history
Complete words from the shell's command history. This
completer can be controlled by the remove-all-dups, and sort
styles as for the _history_complete_word bindable command, see
the section `Bindable Commands' below and the section
`Completion System Configuration' above.

_ignored
The ignored-patterns style can be set to a list of patterns
which are compared against possible completions; matching ones
are removed. With this completer those matches can be
reinstated, as if no ignored-patterns style were set. The
completer actually generates its own list of matches; which
completers are invoked is determined in the same way as for
the _prefix completer. The single-ignored style is also
available as described above.

_list This completer allows the insertion of matches to be delayed
until completion is attempted a second time without the word
on the line being changed. On the first attempt, only the
list of matches will be shown. It is affected by the styles
condition and word, see the section `Completion System
Configuration' above.

_match This completer is intended to be used after the _complete
completer. It behaves similarly but the string on the command
line may be a pattern to match against trial completions.
This gives the effect of the GLOB_COMPLETE option.

Normally completion will be performed by taking the pattern
from the line, inserting a `*' at the cursor position and
comparing the resulting pattern with the possible completions
generated. This can be modified with the match-original style
described above.

The generated matches will be offered in a menu completion
unless the insert-unambiguous style is set to `true'; see the
description above for other options for this style.

Note that matcher specifications defined globally or used by
the completion functions (the styles matcher-list and matcher)
will not be used.

_menu This completer was written as simple example function to show
how menu completion can be enabled in shell code. However, it
has the notable effect of disabling menu selection which can
be useful with _generic based widgets. It should be used as
the first completer in the list. Note that this is
independent of the setting of the MENU_COMPLETE option and
does not work with the other menu completion widgets such as
reverse-menu-complete, or accept-and-menu-complete.

_oldlist
This completer controls how the standard completion widgets
behave when there is an existing list of completions which may
have been generated by a special completion (i.e. a
separately-bound completion command). It allows the ordinary
completion keys to continue to use the list of completions
thus generated, instead of producing a new list of ordinary
contextual completions. It should appear in the list of
completers before any of the widgets which generate matches.
It uses two styles: old-list and old-menu, see the section
`Completion System Configuration' above.

_precommand
Complete an external command in word-separated arguments, as
for exec and /usr/bin/env.

_prefix
This completer can be used to try completion with the suffix
(everything after the cursor) ignored. In other words, the
suffix will not be considered to be part of the word to
complete. The effect is similar to the
expand-or-complete-prefix command.

The completer style is used to decide which other completers
are to be called to generate matches. If this style is unset,
the list of completers set for the current context is used --
except, of course, the _prefix completer itself. Furthermore,
if this completer appears more than once in the list of
completers only those completers not already tried by the last
invocation of _prefix will be called.

For example, consider this global completer style:

zstyle ':completion:*' completer \
_complete _prefix _correct _prefix:foo

Here, the _prefix completer tries normal completion but
ignoring the suffix. If that doesn't generate any matches,
and neither does the call to the _correct completer after it,
_prefix will be called a second time and, now only trying
correction with the suffix ignored. On the second invocation
the completer part of the context appears as `foo'.

To use _prefix as the last resort and try only normal
completion when it is invoked:

zstyle ':completion:*' completer _complete ... _prefix
zstyle ':completion::prefix:*' completer _complete

The add-space style is also respected. If it is set to `true'
then _prefix will insert a space between the matches generated
(if any) and the suffix.

Note that this completer is only useful if the
COMPLETE_IN_WORD option is set; otherwise, the cursor will be
moved to the end of the current word before the completion
code is called and hence there will be no suffix.

_user_expand
This completer behaves similarly to the _expand completer but
instead performs expansions defined by users. The styles
add-space and sort styles specific to the _expand completer
are usable with _user_expand in addition to other styles
handled more generally by the completion system. The tag
all-expansions is also available.

The expansion depends on the array style user-expand being
defined for the current context; remember that the context for
completers is less specific than that for contextual
completion as the full context has not yet been determined.
Elements of the array may have one of the following forms:

$hash

hash is the name of an associative array. Note this is
not a full parameter expression, merely a $, suitably
quoted to prevent immediate expansion, followed by the
name of an associative array. If the trial expansion
word matches a key in hash, the resulting expansion is
the corresponding value.
_func

_func is the name of a shell function whose name must
begin with _ but is not otherwise special to the
completion system. The function is called with the
trial word as an argument. If the word is to be
expanded, the function should set the array reply to a
list of expansions. Optionally, it can set REPLY to a
word that will be used as a description for the set of
expansions. The return status of the function is
irrelevant.

BINDABLE COMMANDS

In addition to the context-dependent completions provided, which are
expected to work in an intuitively obvious way, there are a few
widgets implementing special behaviour which can be bound separately
to keys. The following is a list of these and their default
bindings.

_bash_completions
This function is used by two widgets, _bash_complete-word and
_bash_list-choices. It exists to provide compatibility with
completion bindings in bash. The last character of the
binding determines what is completed: `!', command names; `$',
environment variables; `@', host names; `/', file names; `~'
user names. In bash, the binding preceded by `\e' gives
completion, and preceded by `^X' lists options. As some of
these bindings clash with standard zsh bindings, only `\e~'
and `^X~' are bound by default. To add the rest, the
following should be added to .zshrc after compinit has been
run:

for key in '!' '$' '@' '/' '~'; do
bindkey "\e$key" _bash_complete-word
bindkey "^X$key" _bash_list-choices
done

This includes the bindings for `~' in case they were already
bound to something else; the completion code does not override
user bindings.

_correct_filename (^XC)
Correct the filename path at the cursor position. Allows up
to six errors in the name. Can also be called with an
argument to correct a filename path, independently of zle; the
correction is printed on standard output.

_correct_word (^Xc)
Performs correction of the current argument using the usual
contextual completions as possible choices. This stores the
string `correct-word' in the function field of the context
name and then calls the _correct completer.

_expand_alias (^Xa)
This function can be used as a completer and as a bindable
command. It expands the word the cursor is on if it is an
alias. The types of alias expanded can be controlled with the
styles regular, global and disabled.

When used as a bindable command there is one additional
feature that can be selected by setting the complete style to
`true'. In this case, if the word is not the name of an
alias, _expand_alias tries to complete the word to a full
alias name without expanding it. It leaves the cursor
directly after the completed word so that invoking
_expand_alias once more will expand the now-complete alias
name.

_expand_word (^Xe)
Performs expansion on the current word: equivalent to the
standard expand-word command, but using the _expand completer.
Before calling it, the function field of the context is set to
`expand-word'.

_generic
This function is not defined as a widget and not bound by
default. However, it can be used to define a widget and will
then store the name of the widget in the function field of the
context and call the completion system. This allows custom
completion widgets with their own set of style settings to be
defined easily. For example, to define a widget that performs
normal completion and starts menu selection:

zle -C foo complete-word _generic
bindkey '...' foo
zstyle ':completion:foo:*' menu yes select=1

Note in particular that the completer style may be set for the
context in order to change the set of functions used to
generate possible matches. If _generic is called with
arguments, those are passed through to _main_complete as the
list of completers in place of those defined by the completer
style.

_history_complete_word (\e/)
Complete words from the shell's command history. This uses the
list, remove-all-dups, sort, and stop styles.

_most_recent_file (^Xm)
Complete the name of the most recently modified file matching
the pattern on the command line (which may be blank). If
given a numeric argument N, complete the Nth most recently
modified file. Note the completion, if any, is always unique.

_next_tags (^Xn)
This command alters the set of matches used to that for the
next tag, or set of tags, either as given by the tag-order
style or as set by default; these matches would otherwise not
be available. Successive invocations of the command cycle
through all possible sets of tags.

_read_comp (^X^R)
Prompt the user for a string, and use that to perform
completion on the current word. There are two possibilities
for the string. First, it can be a set of words beginning
`_', for example `_files -/', in which case the function with
any arguments will be called to generate the completions.
Unambiguous parts of the function name will be completed
automatically (normal completion is not available at this
point) until a space is typed.

Second, any other string will be passed as a set of arguments
to compadd and should hence be an expression specifying what
should be completed.

A very restricted set of editing commands is available when
reading the string: `DEL' and `^H' delete the last character;
`^U' deletes the line, and `^C' and `^G' abort the function,
while `RET' accepts the completion. Note the string is used
verbatim as a command line, so arguments must be quoted in
accordance with standard shell rules.

Once a string has been read, the next call to _read_comp will
use the existing string instead of reading a new one. To
force a new string to be read, call _read_comp with a numeric
argument.

_complete_debug (^X?)
This widget performs ordinary completion, but captures in a
temporary file a trace of the shell commands executed by the
completion system. Each completion attempt gets its own file.
A command to view each of these files is pushed onto the
editor buffer stack.

_complete_help (^Xh)
This widget displays information about the context names, the
tags, and the completion functions used when completing at the
current cursor position. If given a numeric argument other
than 1 (as in `ESC-2 ^Xh'), then the styles used and the
contexts for which they are used will be shown, too.

Note that the information about styles may be incomplete; it
depends on the information available from the completion
functions called, which in turn is determined by the user's
own styles and other settings.

_complete_help_generic
Unlike other commands listed here, this must be created as a
normal ZLE widget rather than a completion widget (i.e. with
zle -N). It is used for generating help with a widget bound
to the _generic widget that is described above.

If this widget is created using the name of the function, as
it is by default, then when executed it will read a key
sequence. This is expected to be bound to a call to a
completion function that uses the _generic widget. That
widget will be executed, and information provided in the same
format that the _complete_help widget displays for contextual
completion.

If the widget's name contains debug, for example if it is
created as `zle -N _complete_debug_generic
_complete_help_generic', it will read and execute the
keystring for a generic widget as before, but then generate
debugging information as done by _complete_debug for
contextual completion.

If the widget's name contains noread, it will not read a
keystring but instead arrange that the next use of a generic
widget run in the same shell will have the effect as described
above.

The widget works by setting the shell parameter
ZSH_TRACE_GENERIC_WIDGET which is read by _generic. Unsetting
the parameter cancels any pending effect of the noread form.

For example, after executing the following:

zle -N _complete_debug_generic _complete_help_generic
bindkey '^x:' _complete_debug_generic

typing `C-x :' followed by the key sequence for a generic
widget will cause trace output for that widget to be saved to
a file.

_complete_tag (^Xt)
This widget completes symbol tags created by the etags or
ctags programmes (note there is no connection with the
completion system's tags) stored in a file TAGS, in the format
used by etags, or tags, in the format created by ctags. It
will look back up the path hierarchy for the first occurrence
of either file; if both exist, the file TAGS is preferred.
You can specify the full path to a TAGS or tags file by
setting the parameter $TAGSFILE or $tagsfile respectively.
The corresponding completion tags used are etags and vtags,
after emacs and vi respectively.

UTILITY FUNCTIONS

Descriptions follow for utility functions that may be useful when
writing completion functions. If functions are installed in
subdirectories, most of these reside in the Base subdirectory. Like
the example functions for commands in the distribution, the utility
functions generating matches all follow the convention of returning
status zero if they generated completions and non-zero if no matching
completions could be added.

_absolute_command_paths
This function completes external commands as absolute paths
(unlike _command_names -e which completes their basenames).
It takes no arguments.

_all_labels [ -x ] [ -12VJ ] tag name descr [ command arg ... ]
This is a convenient interface to the _next_label function
below, implementing the loop shown in the _next_label example.
The command and its arguments are called to generate the
matches. The options stored in the parameter name will
automatically be inserted into the args passed to the command.
Normally, they are put directly after the command, but if one
of the args is a single hyphen, they are inserted directly
before that. If the hyphen is the last argument, it will be
removed from the argument list before the command is called.
This allows _all_labels to be used in almost all cases where
the matches can be generated by a single call to the compadd
builtin command or by a call to one of the utility functions.

For example:

local expl
...
if _requested foo; then
...
_all_labels foo expl '...' compadd ... - $matches
fi

Will complete the strings from the matches parameter, using
compadd with additional options which will take precedence
over those generated by _all_labels.

_alternative [ -O name ] [ -C name ] spec ...
This function is useful in simple cases where multiple tags
are available. Essentially it implements a loop like the one
described for the _tags function below.

The tags to use and the action to perform if a tag is
requested are described using the specs which are of the form:
`tag:descr:action'. The tags are offered using _tags and if
the tag is requested, the action is executed with the given
description descr. The actions are those accepted by the
_arguments function (described below), with the following
exceptions:
+o The `->state' and `=...' forms are not supported.


+o The `((a\:bar b\:baz))' form does not need the colon to
be escaped, since the specs have no colon-separated
fields after the action.


For example, the action may be a simple function call:

_alternative \
'users:user:_users' \
'hosts:host:_hosts'

offers usernames and hostnames as possible matches, generated
by the _users and _hosts functions respectively.

Like _arguments, this function uses _all_labels to execute the
actions, which will loop over all sets of tags. Special
handling is only required if there is an additional valid tag,
for example inside a function called from _alternative.

The option `-O name' is used in the same way as by the
_arguments function. In other words, the elements of the name
array will be passed to compadd when executing an action.

Like _tags this function supports the -C option to give a
different name for the argument context field.


_arguments [ -nswWCRS ] [ -A pat ] [ -O name ] [ -M matchspec ]
[ : ] spec ...
_arguments [ opt ... ] -- [ -l ] [ -i pats ] [ -s pair ]
[ helpspec ...]
This function can be used to give a complete specification for
completion for a command whose arguments follow standard UNIX
option and argument conventions.

Options Overview

Options to _arguments itself must be in separate words, i.e.
-s -w, not -sw. The options are followed by specs that
describe options and arguments of the analyzed command. To
avoid ambiguity, all options to _arguments itself may be
separated from the spec forms by a single colon.

The `--' form is used to intuit spec forms from the help
output of the command being analyzed, and is described in
detail below. The opts for the `--' form are otherwise the
same options as the first form. Note that `-s' following `--'
has a distinct meaning from `-s' preceding `--', and both may
appear.

The option switches -s, -S, -A, -w, and -W affect how
_arguments parses the analyzed command line's options. These
switches are useful for commands with standard argument
parsing.

The options of _arguments have the following meanings:

-n With this option, _arguments sets the parameter NORMARG
to the position of the first normal argument in the
$words array, i.e. the position after the end of the
options. If that argument has not been reached,
NORMARG is set to -1. The caller should declare
`integer NORMARG' if the -n option is passed; otherwise
the parameter is not used.

-s Enable option stacking for single-letter options,
whereby multiple single-letter options may be combined
into a single word. For example, the two options `-x'
and `-y' may be combined into a single word `-xy'. By
default, every word corresponds to a single option name
(`-xy' is a single option named `xy').

Options beginning with a single hyphen or plus sign are
eligible for stacking; words beginning with two hyphens
are not.

Note that -s after -- has a different meaning, which is
documented in the segment entitled `Deriving spec forms
from the help output'.

-w In combination with -s, allow option stacking even if
one or more of the options take arguments. For
example, if -x takes an argument, with no -s, `-xy' is
considered as a single (unhandled) option; with -s, -xy
is an option with the argument `y'; with both -s and
-w, -xy is the option -x and the option -y with
arguments to -x (and to -y, if it takes arguments)
still to come in subsequent words.

-W This option takes -w a stage further: it is possible
to complete single-letter options even after an
argument that occurs in the same word. However, it
depends on the action performed whether options will
really be completed at this point. For more control,
use a utility function like _guard as part of the
action.

-C Modify the curcontext parameter for an action of the
form `->state'. This is discussed in detail below.

-R Return status 300 instead of zero when a $state is to
be handled, in the `->string' syntax.

-S Do not complete options after a `--' appearing on the
line, and ignore the `--'. For example, with -S, in
the line

foobar -x -- -y

the `-x' is considered an option, the `-y' is
considered an argument, and the `--' is considered to
be neither.

-A pat Do not complete options after the first non-option
argument on the line. pat is a pattern matching all
strings which are not to be taken as arguments. For
example, to make _arguments stop completing options
after the first normal argument, but ignoring all
strings starting with a hyphen even if they are not
described by one of the optspecs, the form is `-A
"-*"'.

-O name
Pass the elements of the array name as arguments to
functions called to execute actions. This is discussed
in detail below.

-M matchspec
Use the match specification matchspec for completing
option names and values. The default matchspec allows
partial word completion after `_' and `-', such as
completing `-f-b' to `-foo-bar'. The default matchspec
is:
r:|[_-]=* r:|=*

-0 When populating values of the `opt_args' associative
array, don't backslash-escape colons and backslashes
and use NUL rather than colon for joining multiple
values. This option is described in more detail below,
under the heading specs: actions.

specs: overview

Each of the following forms is a spec describing individual
sets of options or arguments on the command line being
analyzed.

n:message:action
n::message:action
This describes the n'th normal argument. The message
will be printed above the matches generated and the
action indicates what can be completed in this position
(see below). If there are two colons before the
message the argument is optional. If the message
contains only white space, nothing will be printed
above the matches unless the action adds an explanation
string itself.

:message:action
::message:action
Similar, but describes the next argument, whatever
number that happens to be. If all arguments are
specified in this form in the correct order the numbers
are unnecessary.

*:message:action
*::message:action
*:::message:action
This describes how arguments (usually non-option
arguments, those not beginning with - or +) are to be
completed when neither of the first two forms was
provided. Any number of arguments can be completed in
this fashion.

With two colons before the message, the words special
array and the CURRENT special parameter are modified to
refer only to the normal arguments when the action is
executed or evaluated. With three colons before the
message they are modified to refer only to the normal
arguments covered by this description.

optspec
optspec:...
This describes an option. The colon indicates handling
for one or more arguments to the option; if it is not
present, the option is assumed to take no arguments.

The following forms are available for the initial
optspec, whether or not the option has arguments.

*optspec
Here optspec is one of the remaining forms
below. This indicates the following optspec may
be repeated. Otherwise if the corresponding
option is already present on the command line to
the left of the cursor it will not be offered
again.

-optname
+optname
In the simplest form the optspec is just the
option name beginning with a minus or a plus
sign, such as `-foo'. The first argument for
the option (if any) must follow as a separate
word directly after the option.

Either of `-+optname' and `+-optname' can be
used to specify that -optname and +optname are
both valid.

In all the remaining forms, the leading `-' may
be replaced by or paired with `+' in this way.

-optname-
The first argument of the option must come
directly after the option name in the same word.
For example, `-foo-:...' specifies that the
completed option and argument will look like
`-fooarg'.

-optname+
The first argument may appear immediately after
optname in the same word, or may appear as a
separate word after the option. For example,
`-foo+:...' specifies that the completed option
and argument will look like either `-fooarg' or
`-foo arg'.

-optname=
The argument may appear as the next word, or in
same word as the option name provided that it is
separated from it by an equals sign, for example
`-foo=arg' or `-foo arg'.

-optname=-
The argument to the option must appear after an
equals sign in the same word, and may not be
given in the next argument.

optspec[explanation]
An explanation string may be appended to any of
the preceding forms of optspec by enclosing it
in brackets, as in `-q[query operation]'.

The verbose style is used to decide whether the
explanation strings are displayed with the
option in a completion listing.

If no bracketed explanation string is given but
the auto-description style is set and only one
argument is described for this optspec, the
value of the style is displayed, with any
appearance of the sequence `%d' in it replaced
by the message of the first optarg that follows
the optspec; see below.

It is possible for options with a literal `+' or `=' to
appear, but that character must be quoted, for example
`-\+'.

Each optarg following an optspec must take one of the
following forms:

:message:action
::message:action
An argument to the option; message and action
are treated as for ordinary arguments. In the
first form, the argument is mandatory, and in
the second form it is optional.

This group may be repeated for options which
take multiple arguments. In other words,
:message1:action1:message2:action2 specifies
that the option takes two arguments.

:*pattern:message:action
:*pattern::message:action
:*pattern:::message:action
This describes multiple arguments. Only the
last optarg for an option taking multiple
arguments may be given in this form. If the
pattern is empty (i.e. :*:), all the remaining
words on the line are to be completed as
described by the action; otherwise, all the
words up to and including a word matching the
pattern are to be completed using the action.

Multiple colons are treated as for the `*:...'
forms for ordinary arguments: when the message
is preceded by two colons, the words special
array and the CURRENT special parameter are
modified during the execution or evaluation of
the action to refer only to the words after the
option. When preceded by three colons, they are
modified to refer only to the words covered by
this description.

Any literal colon in an optname, message, or action must be
preceded by a backslash, `\:'.

Each of the forms above may be preceded by a list in
parentheses of option names and argument numbers. If the
given option is on the command line, the options and arguments
indicated in parentheses will not be offered. For example,
`(-two -three 1)-one:...' completes the option `-one'; if this
appears on the command line, the options -two and -three and
the first ordinary argument will not be completed after it.
`(-foo):...' specifies an ordinary argument completion; -foo
will not be completed if that argument is already present.

Other items may appear in the list of excluded options to
indicate various other items that should not be applied when
the current specification is matched: a single star (*) for
the rest arguments (i.e. a specification of the form `*:...');
a colon (:) for all normal (non-option-) arguments; and a
hyphen (-) for all options. For example, if `(*)' appears
before an option and the option appears on the command line,
the list of remaining arguments (those shown in the above
table beginning with `*:') will not be completed.

To aid in reuse of specifications, it is possible to precede
any of the forms above with `!'; then the form will no longer
be completed, although if the option or argument appears on
the command line they will be skipped as normal. The main use
for this is when the arguments are given by an array, and
_arguments is called repeatedly for more specific contexts: on
the first call `_arguments $global_options' is used, and on
subsequent calls `_arguments !$^global_options'.

specs: actions


In each of the forms above the action determines how
completions should be generated. Except for the `->string'
form below, the action will be executed by calling the
_all_labels function to process all tag labels. No special
handling of tags is needed unless a function call introduces a
new one.

The functions called to execute actions will be called with
the elements of the array named by the `-O name' option as
arguments. This can be used, for example, to pass the same
set of options for the compadd builtin to all actions.

The forms for action are as follows.

(single unquoted space)
This is useful where an argument is required but it is
not possible or desirable to generate matches for it.
The message will be displayed but no completions
listed. Note that even in this case the colon at the
end of the message is needed; it may only be omitted
when neither a message nor an action is given.

(item1 item2 ...)
One of a list of possible matches, for example:

:foo:(foo bar baz)

((item1\:desc1 ...))
Similar to the above, but with descriptions for each
possible match. Note the backslash before the colon.
For example,

:foo:((a\:bar b\:baz))

The matches will be listed together with their
descriptions if the description style is set with the
values tag in the context.

->string
In this form, _arguments processes the arguments and
options and then returns control to the calling
function with parameters set to indicate the state of
processing; the calling function then makes its own
arrangements for generating completions. For example,
functions that implement a state machine can use this
type of action.

Where _arguments encounters action in the `->string'
format, it will strip all leading and trailing
whitespace from string and set the array state to the
set of all strings for which an action is to be
performed. The elements of the array state_descr are
assigned the corresponding message field from each
optarg containing such an action.

By default and in common with all other well behaved
completion functions, _arguments returns status zero if
it was able to add matches and non-zero otherwise.
However, if the -R option is given, _arguments will
instead return a status of 300 to indicate that $state
is to be handled.

In addition to $state and $state_descr, _arguments also
sets the global parameters `context', `line' and
`opt_args' as described below, and does not reset any
changes made to the special parameters such as PREFIX
and words. This gives the calling function the choice
of resetting these parameters or propagating changes in
them.

A function calling _arguments with at least one action
containing a `->string' must therefore declare
appropriate local parameters:

local context state state_descr line
typeset -A opt_args

to prevent _arguments from altering the global
environment.

{eval-string}
A string in braces is evaluated as shell code to
generate matches. If the eval-string itself does not
begin with an opening parenthesis or brace it is split
into separate words before execution.

= action
If the action starts with `= ' (an equals sign followed
by a space), _arguments will insert the contents of the
argument field of the current context as the new first
element in the words special array and increment the
value of the CURRENT special parameter. This has the
effect of inserting a dummy word onto the completion
command line while not changing the point at which
completion is taking place.

This is most useful with one of the specifiers that
restrict the words on the command line on which the
action is to operate (the two- and three-colon forms
above). One particular use is when an action itself
causes _arguments on a restricted range; it is
necessary to use this trick to insert an appropriate
command name into the range for the second call to
_arguments to be able to parse the line.

word...
word...
This covers all forms other than those above. If the
action starts with a space, the remaining list of words
will be invoked unchanged.

Otherwise it will be invoked with some extra strings
placed after the first word; these are to be passed
down as options to the compadd builtin. They ensure
that the state specified by _arguments, in particular
the descriptions of options and arguments, is correctly
passed to the completion command. These additional
arguments are taken from the array parameter `expl';
this will be set up before executing the action and
hence may be referred to inside it, typically in an
expansion of the form `$expl[@]' which preserves empty
elements of the array.

During the performance of the action the array `line' will be
set to the normal arguments from the command line, i.e. the
words from the command line after the command name excluding
all options and their arguments. Options are stored in the
associative array `opt_args' with option names as keys and
their arguments as the values. By default, all colons and
backslashes in the value are escaped with backslashes, and if
an option has multiple arguments (for example, when using an
optspec of the form `*optspec'), they are joined with
(unescaped) colons. However, if the -0 option was passed, no
backslash escaping is performed, and multiple values are
joined with NUL bytes. For example, after `zsh -o foo:foo -o
bar:bar -o <TAB>', the contents of `opt_args' would be

typeset -A opt_args=( [-o]='foo\:foo:bar\:bar:' )

by default, and

typeset -A opt_args=( [-o]=$'foo:foo\x00bar:bar\x00' )

if _arguments had been called with the -0 option.

The parameter `context' is set when returning to the calling
function to perform an action of the form `->string'. It is
set to an array of elements corresponding to the elements of
$state. Each element is a suitable name for the argument
field of the context: either a string of the form
`option-opt-n' for the n'th argument of the option -opt, or a
string of the form `argument-n' for the n'th argument. For
`rest' arguments, that is those in the list at the end not
handled by position, n is the string `rest'. For example,
when completing the argument of the -o option, the name is
`option-o-1', while for the second normal (non-option-)
argument it is `argument-2'.

Furthermore, during the evaluation of the action the context
name in the curcontext parameter is altered to append the same
string that is stored in the context parameter.

The option -C tells _arguments to modify the curcontext
parameter for an action of the form `->state'. This is the
standard parameter used to keep track of the current context.
Here it (and not the context array) should be made local to
the calling function to avoid passing back the modified value
and should be initialised to the current value at the start of
the function:

local curcontext="$curcontext"

This is useful where it is not possible for multiple states to
be valid together.

Grouping Options

Options can be grouped to simplify exclusion lists. A group is
introduced with `+' followed by a name for the group in the
subsequent word. Whole groups can then be referenced in an
exclusion list or a group name can be used to disambiguate
between two forms of the same option. For example:

_arguments \
'(group2--x)-a' \
+ group1 \
-m \
'(group2)-n' \
+ group2 \
-x -y

If the name of a group is specified in the form `(name)' then
only one value from that group will ever be completed; more
formally, all specifications are mutually exclusive to all
other specifications in that group. This is useful for
defining options that are aliases for each other. For example:

_arguments \
-a -b \
+ '(operation)' \
{-c,--compress}'[compress]' \
{-d,--decompress}'[decompress]' \
{-l,--list}'[list]'

If an option in a group appears on the command line, it is
stored in the associative array `opt_args' with 'group-option'
as a key. In the example above, a key `operation--c' is used
if the option `-c' is present on the command line.

Specifying Multiple Sets of Arguments

It is possible to specify multiple sets of options and
arguments with the sets separated by single hyphens. This
differs from groups in that sets are considered to be mutually
exclusive of each other.

Specifications before the first set and from any group are
common to all sets. For example:

_arguments \
-a \
- set1 \
-c \
- set2 \
-d \
':arg:(x2 y2)'

This defines two sets. When the command line contains the
option `-c', the `-d' option and the argument will not be
considered possible completions. When it contains `-d' or an
argument, the option `-c' will not be considered. However,
after `-a' both sets will still be considered valid.

As for groups, the name of a set may appear in exclusion
lists, either alone or preceding a normal option or argument
specification.

The completion code has to parse the command line separately
for each set. This can be slow so sets should only be used
when necessary. A useful alternative is often an option
specification with rest-arguments (as in `-foo:*:...'); here
the option -foo swallows up all remaining arguments as
described by the optarg definitions.

Deriving spec forms from the help output

The option `--' allows _arguments to work out the names of
long options that support the `--help' option which is
standard in many GNU commands. The command word is called
with the argument `--help' and the output examined for option
names. Clearly, it can be dangerous to pass this to commands
which may not support this option as the behaviour of the
command is unspecified.

In addition to options, `_arguments --' will try to deduce the
types of arguments available for options when the form
`--opt=val' is valid. It is also possible to provide hints by
examining the help text of the command and adding helpspec of
the form `pattern:message:action'; note that other _arguments
spec forms are not used. The pattern is matched against the
help text for an option, and if it matches the message and
action are used as for other argument specifiers. The special
case of `*:' means both message and action are empty, which
has the effect of causing options having no description in the
help output to be ordered in listings ahead of options that
have a description.

For example:

_arguments -- '*\*:toggle:(yes no)' \
'*=FILE*:file:_files' \
'*=DIR*:directory:_files -/' \
'*=PATH*:directory:_files -/'

Here, `yes' and `no' will be completed as the argument of
options whose description ends in a star; file names will be
completed for options that contain the substring `=FILE' in
the description; and directories will be completed for options
whose description contains `=DIR' or `=PATH'. The last three
are in fact the default and so need not be given explicitly,
although it is possible to override the use of these patterns.
A typical help text which uses this feature is:

-C, --directory=DIR change to directory DIR

so that the above specifications will cause directories to be
completed after `--directory', though not after `-C'.

Note also that _arguments tries to find out automatically if
the argument for an option is optional. This can be specified
explicitly by doubling the colon before the message.

If the pattern ends in `(-)', this will be removed from the
pattern and the action will be used only directly after the
`=', not in the next word. This is the behaviour of a normal
specification defined with the form `=-'.

By default, the command (with the option `--help') is run
after resetting all the locale categories (except for
LC_CTYPE) to `C'. If the localized help output is known to
work, the option `-l' can be specified after the `_arguments
--' so that the command is run in the current locale.

The `_arguments --' can be followed by the option `-i
patterns' to give patterns for options which are not to be
completed. The patterns can be given as the name of an array
parameter or as a literal list in parentheses. For example,

_arguments -- -i \
"(--(en|dis)able-FEATURE*)"

will cause completion to ignore the options `--enable-FEATURE'
and `--disable-FEATURE' (this example is useful with GNU
configure).

The `_arguments --' form can also be followed by the option
`-s pair' to describe option aliases. The pair consists of a
list of alternating patterns and corresponding replacements,
enclosed in parens and quoted so that it forms a single
argument word in the _arguments call.

For example, some configure-script help output describes
options only as `--enable-foo', but the script also accepts
the negated form `--disable-foo'. To allow completion of the
second form:

_arguments -- -s "((#s)--enable- --disable-)"

Miscellaneous notes

Finally, note that _arguments generally expects to be the
primary function handling any completion for which it is used.
It may have side effects which change the treatment of any
matches added by other functions called after it. To combine
_arguments with other functions, those functions should be
called either before _arguments, as an action within a spec,
or in handlers for `->state' actions.

Here is a more general example of the use of _arguments:

_arguments '-l+:left border:' \
'-format:paper size:(letter A4)' \
'*-copy:output file:_files::resolution:(300 600)' \
':postscript file:_files -g \*.\(ps\|eps\)' \
'*:page number:'

This describes three options: `-l', `-format', and `-copy'.
The first takes one argument described as `left border' for
which no completion will be offered because of the empty
action. Its argument may come directly after the `-l' or it
may be given as the next word on the line.

The `-format' option takes one argument in the next word,
described as `paper size' for which only the strings `letter'
and `A4' will be completed.

The `-copy' option may appear more than once on the command
line and takes two arguments. The first is mandatory and will
be completed as a filename. The second is optional (because
of the second colon before the description `resolution') and
will be completed from the strings `300' and `600'.

The last two descriptions say what should be completed as
arguments. The first describes the first argument as a
`postscript file' and makes files ending in `ps' or `eps' be
completed. The last description gives all other arguments the
description `page number' but does not offer completions.

_cache_invalid cache_identifier
This function returns status zero if the completions cache
corresponding to the given cache identifier needs rebuilding.
It determines this by looking up the cache-policy style for
the current context. This should provide a function name
which is run with the full path to the relevant cache file as
the only argument.

Example:

_example_caching_policy () {
# rebuild if cache is more than a week old
local -a oldp
oldp=( "$1"(Nm+7) )
(( $#oldp ))
}

_call_function return name [ arg ... ]
If a function name exists, it is called with the arguments
args. The return argument gives the name of a parameter in
which the return status from the function name should be
stored; if return is empty or a single hyphen it is ignored.

The return status of _call_function itself is zero if the
function name exists and was called and non-zero otherwise.

_call_program [ -l ] [ -p ] tag string ...
This function provides a mechanism for the user to override
the use of an external command. It looks up the command style
with the supplied tag. If the style is set, its value is used
as the command to execute. The strings from the call to
_call_program, or from the style if set, are concatenated with
spaces between them and the resulting string is evaluated.
The return status is the return status of the command called.

By default, the command is run in an environment where all the
locale categories (except for LC_CTYPE) are reset to `C' by
calling the utility function _comp_locale (see below). If the
option `-l' is given, the command is run with the current
locale.

If the option `-p' is supplied it indicates that the command
output is influenced by the permissions it is run with. If the
gain-privileges style is set to true, _call_program will make
use of commands such as sudo, if present on the command-line,
to match the permissions to whatever the final command is
likely to run under. When looking up the gain-privileges and
command styles, the command component of the zstyle context
will end with a slash (`/') followed by the command that would
be used to gain privileges.

_combination [ -s pattern ] tag style spec ... field opts ...
This function is used to complete combinations of values, for
example pairs of hostnames and usernames. The style argument
gives the style which defines the pairs; it is looked up in a
context with the tag specified.

The style name consists of field names separated by hyphens,
for example `users-hosts-ports'. For each field for a value
is already known, a spec of the form `field=pattern' is given.
For example, if the command line so far specifies a user
`pws', the argument `users=pws' should appear.

The next argument with no equals sign is taken as the name of
the field for which completions should be generated
(presumably not one of the fields for which the value is
known).

The matches generated will be taken from the value of the
style. These should contain the possible values for the
combinations in the appropriate order (users, hosts, ports in
the example above). The values for the different fields are
separated by colons. This can be altered with the option -s
to _combination which specifies a pattern. Typically this is
a character class, as for example `-s "[:@]"' in the case of
the users-hosts style. Each `field=pattern' specification
restricts the completions which apply to elements of the style
with appropriately matching fields.

If no style with the given name is defined for the given tag,
or if none of the strings in style's value match, but a
function name of the required field preceded by an underscore
is defined, that function will be called to generate the
matches. For example, if there is no `users-hosts-ports' or
no matching hostname when a host is required, the function
`_hosts' will automatically be called.

If the same name is used for more than one field, in both the
`field=pattern' and the argument that gives the name of the
field to be completed, the number of the field (starting with
one) may be given after the fieldname, separated from it by a
colon.

All arguments after the required field name are passed to
compadd when generating matches from the style value, or to
the functions for the fields if they are called.

_command_names [ -e | - ]
This function completes words that are valid at command
position: names of aliases, builtins, hashed commands,
functions, and so on. With the -e flag, only hashed commands
are completed. The - flag is ignored.

_comp_locale
This function resets all the locale categories other than
LC_CTYPE to `C' so that the output from external commands can
be easily analyzed by the completion system. LC_CTYPE retains
the current value (taking LC_ALL and LANG into account),
ensuring that non-ASCII characters in file names are still
handled properly.

This function should normally be run only in a subshell,
because the new locale is exported to the environment. Typical
usage would be `$(_comp_locale; command ...)'.

_completers [ -p ]
This function completes names of completers.

-p Include the leading underscore (`_') in the matches.

_default
This function corresponds to the -default- special context
which is applied where no completion is defined. It is useful
to call it under certain error conditions such as completion
after an unrecognised subcommand. This applies the concept of
graceful degradation to the completion system, allowing it to
fallback on basic completion of commonly useful things like
filenames.


_describe [-12JVx] [ -oO | -t tag ] descr name1 [ name2 ] [ opt ... ]
[ -- name1 [ name2 ] [ opt ... ] ... ]
This function associates completions with descriptions.
Multiple groups separated by -- can be supplied, potentially
with different completion options opts.

The descr is taken as a string to display above the matches if
the format style for the descriptions tag is set. This is
followed by one or two names of arrays followed by options to
pass to compadd. The array name1 contains the possible
completions with their descriptions in the form
`completion:description'. Any literal colons in completion
must be quoted with a backslash. If a name2 is given, it
should have the same number of elements as name1; in this case
the corresponding elements are added as possible completions
instead of the completion strings from name1. The completion
list will retain the descriptions from name1. Finally, a set
of completion options can appear.

If the option `-o' appears before the first argument, the
matches added will be treated as names of command options
(N.B. not shell options), typically following a `-', `--' or
`+' on the command line. In this case _describe uses the
prefix-hidden, prefix-needed and verbose styles to find out if
the strings should be added as completions and if the
descriptions should be shown. Without the `-o' option, only
the verbose style is used to decide how descriptions are
shown. If `-O' is used instead of `-o', command options are
completed as above but _describe will not handle the
prefix-needed style.

With the -t option a tag can be specified. The default is
`values' or, if the -o option is given, `options'.

The options -1, -2, -J, -V, -x are passed to _next_label.

If selected by the list-grouped style, strings with the same
description will appear together in the list.

_describe uses the _all_labels function to generate the
matches, so it does not need to appear inside a loop over tag
labels.

_description [ -x ] [ -12VJ ] tag name descr [ spec ... ]
This function is not to be confused with the previous one; it
is used as a helper function for creating options to compadd.
It is buried inside many of the higher level completion
functions and so often does not need to be called directly.

The styles listed below are tested in the current context
using the given tag. The resulting options for compadd are
put into the array named name (this is traditionally `expl',
but this convention is not enforced). The description for the
corresponding set of matches is passed to the function in
descr.

The styles tested are: format, hidden, matcher, ignore-line,
ignored-patterns, group-name and sort. The format style is
first tested for the given tag and then for the descriptions
tag if no value was found, while the remainder are only tested
for the tag given as the first argument. The function also
calls _setup which tests some more styles.

The string returned by the format style (if any) will be
modified so that the sequence `%d' is replaced by the descr
given as the third argument without any leading or trailing
white space. If, after removing the white space, the descr is
the empty string, the format style will not be used and the
options put into the name array will not contain an
explanation string to be displayed above the matches.

If _description is called with more than three arguments, the
additional specs should be of the form `char:str'. These
supply escape sequence replacements for the format style:
every appearance of `%char' will be replaced by string. If no
additional specs are given but the description in descr
conforms to a common form then further escape sequences are
set for elements of that description. These elements
correspond to a default value (`%o'), the units (`%m') range
of acceptable values (`%r') and the remaining initial part of
the description (`%h'). The form the description takes
consists of specifying the units and range in parentheses and
the default value in square brackets, for example:

_description times expl 'timeout (seconds) (0-60) [20]'

It is possible to use zformat conditional expressions when
styling these elements. So, for example, to add `default:' as
a tag but only when there is a default value to show, the
format style might include `%(o.default: %o.)'.

If the -x option is given, the description will be passed to
compadd using the -x option instead of the default -X. This
means that the description will be displayed even if there are
no corresponding matches.

The options placed in the array name take account of the
group-name style, so matches are placed in a separate group
where necessary. The group normally has its elements sorted
(by passing the option -J to compadd), but if an option
starting with `-V', `-J', `-1', or `-2' is passed to
_description, that option will be included in the array.
Hence it is possible for the completion group to be unsorted
by giving the option `-V', `-1V', or `-2V'.

In most cases, the function will be used like this:

local expl
_description files expl file
compadd "$expl[@]" - "$files[@]"

Note the use of the parameter expl, the hyphen, and the list
of matches. Almost all calls to compadd within the completion
system use a similar format; this ensures that user-specified
styles are correctly passed down to the builtins which
implement the internals of completion.

_dir_list [ -s sep ] [ -S ]
Complete a list of directory names separated by colons (the
same format as $PATH).

-s sep Use sep as separator between items. sep defaults to a
colon (`:').

-S Add sep instead of slash (`/') as an autoremoveable
suffix.

_dispatch context string ...
This sets the current context to context and looks for
completion functions to handle this context by hunting through
the list of command names or special contexts (as described
above for compdef) given as strings. The first completion
function to be defined for one of the contexts in the list is
used to generate matches. Typically, the last string is
-default- to cause the function for default completion to be
used as a fallback.

The function sets the parameter $service to the string being
tried, and sets the context/command field (the fourth) of the
$curcontext parameter to the context given as the first
argument.

_email_addresses [ -c ] [ -n plugin ]
Complete email addresses. Addresses are provided by plugins.

-c Complete bare localhost@domain.tld addresses, without a
name part or a comment. Without this option, RFC822
`Firstname Lastname <address>' strings are completed.

-n plugin
Complete aliases from plugin.

The following plugins are available by default: _email-ldap
(see the filter style), _email-local (completes user@hostname
Unix addresses), _email-mail (completes aliases from
~/.mailrc), _email-mush, _email-mutt, and _email-pine.

Addresses from the _email-foo plugin are added under the tag
`email-foo'.

Writing plugins

Plugins are written as separate functions with names starting
with `_email-'. They are invoked with the -c option and
compadd options. They should either do their own completion
or set the $reply array to a list of `alias:address' elements
and return 300. New plugins will be picked up and run
automatically.

_files The function _files is a wrapper around _path_files. It
supports all of the same functionality, with some enhancements
-- notably, it respects the list-dirs-first style, and it
allows users to override the behaviour of the -g and -/
options with the file-patterns style. _files should therefore
be preferred over _path_files in most cases.

This function accepts the full set of options allowed by
_path_files, described below.

_gnu_generic
This function is a simple wrapper around the _arguments
function described above. It can be used to determine
automatically the long options understood by commands that
produce a list when passed the option `--help'. It is
intended to be used as a top-level completion function in its
own right. For example, to enable option completion for the
commands foo and bar, use

compdef _gnu_generic foo bar

after the call to compinit.

The completion system as supplied is conservative in its use
of this function, since it is important to be sure the command
understands the option `--help'.

_guard [ options ] pattern descr
This function displays descr if pattern matches the string to
be completed. It is intended to be used in the action for the
specifications passed to _arguments and similar functions.

The return status is zero if the message was displayed and the
word to complete is not empty, and non-zero otherwise.

The pattern may be preceded by any of the options understood
by compadd that are passed down from _description, namely -M,
-J, -V, -1, -2, -n, -F and -X. All of these options will be
ignored. This fits in conveniently with the argument-passing
conventions of actions for _arguments.

As an example, consider a command taking the options -n and
-none, where -n must be followed by a numeric value in the
same word. By using:

_arguments '-n-: :_guard "[0-9]#" "numeric value"' '-none'

_arguments can be made to both display the message `numeric
value' and complete options after `-n<TAB>'. If the `-n' is
already followed by one or more digits (the pattern passed to
_guard) only the message will be displayed; if the `-n' is
followed by another character, only options are completed.

_message [ -r12 ] [ -VJ group ] descr
_message -e [ tag ] descr
The descr is used in the same way as the third argument to the
_description function, except that the resulting string will
always be shown whether or not matches were generated. This
is useful for displaying a help message in places where no
completions can be generated.

The format style is examined with the messages tag to find a
message; the usual tag, descriptions, is used only if the
style is not set with the former.

If the -r option is given, no style is used; the descr is
taken literally as the string to display. This is most useful
when the descr comes from a pre-processed argument list which
already contains an expanded description. Note that this
option does not disable the `%'-sequence parsing done by
compadd.

The -12VJ options and the group are passed to compadd and
hence determine the group the message string is added to.

The second -e form gives a description for completions with
the tag tag to be shown even if there are no matches for that
tag. This form is called by _arguments in the event that
there is no action for an option specification. The tag can
be omitted and if so the tag is taken from the parameter
$curtag; this is maintained by the completion system and so is
usually correct. Note that if there are no matches at the
time this function is called, compstate[insert] is cleared, so
additional matches generated later are not inserted on the
command line.

_multi_parts [ -i ] sep array
The argument sep is a separator character. The array may be
either the name of an array parameter or a literal array in
the form `(foo bar)', a parenthesised list of words separated
by whitespace. The possible completions are the strings from
the array. However, each chunk delimited by sep will be
completed separately. For example, the _tar function uses
`_multi_parts / patharray' to complete partial file paths from
the given array of complete file paths.

The -i option causes _multi_parts to insert a unique match
even if that requires multiple separators to be inserted.
This is not usually the expected behaviour with filenames, but
certain other types of completion, for example those with a
fixed set of possibilities, may be more suited to this form.

Like other utility functions, this function accepts the `-V',
`-J', `-1', `-2', `-n', `-f', `-X', `-M', `-P', `-S', `-r',
`-R', and `-q' options and passes them to the compadd builtin.

_next_label [ -x ] [ -12VJ ] tag name descr [ option ... ]
This function is used to implement the loop over different tag
labels for a particular tag as described above for the
tag-order style. On each call it checks to see if there are
any more tag labels; if there is it returns status zero,
otherwise non-zero. As this function requires a current tag
to be set, it must always follow a call to _tags or
_requested.

The -x12VJ options and the first three arguments are passed to
the _description function. Where appropriate the tag will be
replaced by a tag label in this call. Any description given
in the tag-order style is preferred to the descr passed to
_next_label.

The options given after the descr are set in the parameter
given by name, and hence are to be passed to compadd or
whatever function is called to add the matches.

Here is a typical use of this function for the tag foo. The
call to _requested determines if tag foo is required at all;
the loop over _next_label handles any labels defined for the
tag in the tag-order style.

local expl ret=1
...
if _requested foo; then
...
while _next_label foo expl '...'; do
compadd "$expl[@]" ... && ret=0
done
...
fi
return ret

_normal [ -P | -p precommand ]
This is the standard function called to handle completion
outside any special -context-. It is called both to complete
the command word and also the arguments for a command. In the
second case, _normal looks for a special completion for that
command, and if there is none it uses the completion for the
-default- context.

A second use is to reexamine the command line specified by the
$words array and the $CURRENT parameter after those have been
modified. For example, the function _precommand, which
completes after precommand specifiers such as nohup, removes
the first word from the words array, decrements the CURRENT
parameter, then calls `_normal -p $service'. The effect is
that `nohup cmd ...' is treated in the same way as `cmd ...'.

-P Reset the list of precommands. This option should be
used if completing a command line which allows internal
commands (e.g. builtins and functions) regardless of
prior precommands (e.g. `zsh -c').

-p precommand
Append precommand to the list of precommands. This
option should be used in nearly all cases in which -P
is not applicable.

If the command name matches one of the patterns given by one
of the options -p or -P to compdef, the corresponding
completion function is called and then the parameter _compskip
is checked. If it is set completion is terminated at that
point even if no matches have been found. This is the same
effect as in the -first- context.

_numbers [ option ... ] [ description ] [ suffix ... ]
This can be used where a number is followed by a suffix to
indicate the units. The unit suffixes are completed and can
also be included in the description used when completion is
invoked for the preceding number.

In addition to common compadd options, _numbers accepts the
following options:

-t tag Specify a tag to use instead of the default of numbers.

-u units
Indicate the default units for the number, e.g. bytes.

-l min Specify the lowest possible value for the number.

-m max Specify the highest possible value for the number.

-d default
Specify the default value.

-N Allow negative numbers. This is implied if the range
includes a negative.

-f Allow decimal numbers.

Where a particular suffix represents the default units for a
number, it should be prefixed with a colon. Additionally,
suffixes can be followed by a colon and a description. So for
example, the following allows the age of something to be
specified, either in seconds or with an optional suffix with a
longer unit of time:

_numbers -u seconds age :s:seconds m:minutes h:hours d:days

It is typically helpful for units to be presented in order of
magnitude when completed. To facilitate this, the order in
which they are given is preserved.

When the format style is looked up with the descriptions tag
or the tag specified with -t, the list of suffixes is
available as a `%x' escape sequence. This is in addition to
the usual sequences documented under the format style. The
form this list takes can also be configured. To this end, the
format style is first looked up with the tag unit-suffixes.
The retrieved format is applied to each suffix in turn and the
results are then concatenated to form the completed list. For
the unit-suffixes format, `%x' expands to the individual
suffix and `%X' to its description. %d' indicates a default
suffix and can be used in a condition. The index and reverse
index are set in `%i' and `%r' respectively and are useful for
text included only with the first and last suffixes in the
list. So for example, the following joins the suffixes
together as a comma-separated list:

zstyle ':completion:*:unit-suffixes' format '%x%(r::,)'

_options
This can be used to complete the names of shell options. It
provides a matcher specification that ignores a leading `no',
ignores underscores and allows upper-case letters to match
their lower-case counterparts (for example, `glob', `noglob',
`NO_GLOB' are all completed). Any arguments are propagated to
the compadd builtin.

_options_set and _options_unset
These functions complete only set or unset options, with the
same matching specification used in the _options function.

Note that you need to uncomment a few lines in the
_main_complete function for these functions to work properly.
The lines in question are used to store the option settings in
effect before the completion widget locally sets the options
it needs. Hence these functions are not generally used by the
completion system.

_parameters
This is used to complete the names of shell parameters.

The option `-g pattern' limits the completion to parameters
whose type matches the pattern. The type of a parameter is
that shown by `print ${(t)param}', hence judicious use of `*'
in pattern is probably necessary.

All other arguments are passed to the compadd builtin.

_path_files
This function is used throughout the completion system to
complete filenames. It allows completion of partial paths.
For example, the string `/u/i/s/sig' may be completed to
`/usr/include/sys/signal.h'.

The options accepted by both _path_files and _files are:

-f Complete all filenames. This is the default.

-/ Specifies that only directories should be completed.

-g pattern
Specifies that only files matching the pattern should
be completed.

-W paths
Specifies path prefixes that are to be prepended to the
string from the command line to generate the filenames
but that should not be inserted as completions nor
shown in completion listings. Here, paths may be the
name of an array parameter, a literal list of paths
enclosed in parentheses or an absolute pathname.

-F ignored-files
This behaves as for the corresponding option to the
compadd builtin. It gives direct control over which
filenames should be ignored. If the option is not
present, the ignored-patterns style is used.

Both _path_files and _files also accept the following options
which are passed to compadd: `-J', `-V', `-1', `-2', `-n',
`-X', `-M', `-P', `-S', `-q', `-r', and `-R'.

Finally, the _path_files function uses the styles expand,
ambiguous, special-dirs, list-suffixes and file-sort described
above.


_pick_variant [ -b builtin-label ] [ -c command ] [ -r name ]
label=pattern ... label [ arg ... ]
This function is used to resolve situations where a single
command name requires more than one type of handling, either
because it has more than one variant or because there is a
name clash between two different commands.

The command to run is taken from the first element of the
array words unless this is overridden by the option -c. This
command is run and its output is compared with a series of
patterns. Arguments to be passed to the command can be
specified at the end after all the other arguments. The
patterns to try in order are given by the arguments
label=pattern; if the output of `command arg ...' contains
pattern, then label is selected as the label for the command
variant. If none of the patterns match, the final command
label is selected and status 1 is returned.

If the `-b builtin-label' is given, the command is tested to
see if it is provided as a shell builtin, possibly autoloaded;
if so, the label builtin-label is selected as the label for
the variant.

If the `-r name' is given, the label picked is stored in the
parameter named name.

The results are also cached in the _cmd_variant associative
array indexed by the name of the command run.

_regex_arguments name spec ...
This function generates a completion function name which
matches the specifications specs, a set of regular expressions
as described below. After running _regex_arguments, the
function name should be called as a normal completion
function. The pattern to be matched is given by the contents
of the words array up to the current cursor position joined
together with null characters; no quotation is applied.

The arguments are grouped as sets of alternatives separated by
`|', which are tried one after the other until one matches.
Each alternative consists of a one or more specifications
which are tried left to right, with each pattern matched being
stripped in turn from the command line being tested, until all
of the group succeeds or until one fails; in the latter case,
the next alternative is tried. This structure can be repeated
to arbitrary depth by using parentheses; matching proceeds
from inside to outside.

A special procedure is applied if no test succeeds but the
remaining command line string contains no null character
(implying the remaining word is the one for which completions
are to be generated). The completion target is restricted to
the remaining word and any actions for the corresponding
patterns are executed. In this case, nothing is stripped from
the command line string. The order of evaluation of the
actions can be determined by the tag-order style; the various
formats supported by _alternative can be used in action. The
descr is used for setting up the array parameter expl.

Specification arguments take one of following forms, in which
metacharacters such as `(', `)', `#' and `|' should be quoted.

/pattern/ [%lookahead%] [-guard] [:tag:descr:action]
This is a single primitive component. The function
tests whether the combined pattern
`(#b)((#B)pattern)lookahead*' matches the command line
string. If so, `guard' is evaluated and its return
status is examined to determine if the test has
succeeded. The pattern string `[]' is guaranteed never
to match. The lookahead is not stripped from the
command line before the next pattern is examined.

The argument starting with : is used in the same manner
as an argument to _alternative.

A component is used as follows: pattern is tested to
see if the component already exists on the command
line. If it does, any following specifications are
examined to find something to complete. If a component
is reached but no such pattern exists yet on the
command line, the string containing the action is used
to generate matches to insert at that point.

/pattern/+ [%lookahead%] [-guard] [:tag:descr:action]
This is similar to `/pattern/ ...' but the left part of
the command line string (i.e. the part already matched
by previous patterns) is also considered part of the
completion target.

/pattern/- [%lookahead%] [-guard] [:tag:descr:action]
This is similar to `/pattern/ ...' but the actions of
the current and previously matched patterns are ignored
even if the following `pattern' matches the empty
string.

( spec )
Parentheses may be used to groups specs; note each
parenthesis is a single argument to _regex_arguments.

spec # This allows any number of repetitions of spec.

spec spec
The two specs are to be matched one after the other as
described above.

spec | spec
Either of the two specs can be matched.

The function _regex_words can be used as a helper function to
generate matches for a set of alternative words possibly with
their own arguments as a command line argument.

Examples:

_regex_arguments _tst /$'[^\0]#\0'/ \
/$'[^\0]#\0'/ :'compadd aaa'

This generates a function _tst that completes aaa as its only
argument. The tag and description for the action have been
omitted for brevity (this works but is not recommended in
normal use). The first component matches the command word,
which is arbitrary; the second matches any argument. As the
argument is also arbitrary, any following component would not
depend on aaa being present.

_regex_arguments _tst /$'[^\0]#\0'/ \
/$'aaa\0'/ :'compadd aaa'

This is a more typical use; it is similar, but any following
patterns would only match if aaa was present as the first
argument.

_regex_arguments _tst /$'[^\0]#\0'/ \( \
/$'aaa\0'/ :'compadd aaa' \
/$'bbb\0'/ :'compadd bbb' \) \#

In this example, an indefinite number of command arguments may
be completed. Odd arguments are completed as aaa and even
arguments as bbb. Completion fails unless the set of aaa and
bbb arguments before the current one is matched correctly.

_regex_arguments _tst /$'[^\0]#\0'/ \
\( /$'aaa\0'/ :'compadd aaa' \| \
/$'bbb\0'/ :'compadd bbb' \) \#

This is similar, but either aaa or bbb may be completed for
any argument. In this case _regex_words could be used to
generate a suitable expression for the arguments.

_regex_words tag description spec ...
This function can be used to generate arguments for the
_regex_arguments command which may be inserted at any point
where a set of rules is expected. The tag and description
give a standard tag and description pertaining to the current
context. Each spec contains two or three arguments separated
by a colon: note that there is no leading colon in this case.

Each spec gives one of a set of words that may be completed at
this point, together with arguments. It is thus roughly
equivalent to the _arguments function when used in normal
(non-regex) completion.

The part of the spec before the first colon is the word to be
completed. This may contain a *; the entire word, before and
after the * is completed, but only the text before the * is
required for the context to be matched, so that further
arguments may be completed after the abbreviated form.

The second part of spec is a description for the word being
completed.

The optional third part of the spec describes how words
following the one being completed are themselves to be
completed. It will be evaluated in order to avoid problems
with quoting. This means that typically it contains a
reference to an array containing previously generated regex
arguments.

The option -t term specifies a terminator for the word instead
of the usual space. This is handled as an auto-removable
suffix in the manner of the option -s sep to _values.

The result of the processing by _regex_words is placed in the
array reply, which should be made local to the calling
function. If the set of words and arguments may be matched
repeatedly, a # should be appended to the generated array at
that point.

For example:

local -a reply
_regex_words mydb-commands 'mydb commands' \
'add:add an entry to mydb:$mydb_add_cmds' \
'show:show entries in mydb'
_regex_arguments _mydb "$reply[@]"
_mydb "$@"

This shows a completion function for a command mydb which
takes two command arguments, add and show. show takes no
arguments, while the arguments for add have already been
prepared in an array mydb_add_cmds, quite possibly by a
previous call to _regex_words.

_requested [ -x ] [ -12VJ ] tag [ name descr [ command [ arg ... ] ]
This function is called to decide whether a tag already
registered by a call to _tags (see below) has been requested
by the user and hence completion should be performed for it.
It returns status zero if the tag is requested and non-zero
otherwise. The function is typically used as part of a loop
over different tags as follows:

_tags foo bar baz
while _tags; do
if _requested foo; then
... # perform completion for foo
fi
... # test the tags bar and baz in the same way
... # exit loop if matches were generated
done

Note that the test for whether matches were generated is not
performed until the end of the _tags loop. This is so that
the user can set the tag-order style to specify a set of tags
to be completed at the same time.

If name and descr are given, _requested calls the _description
function with these arguments together with the options passed
to _requested.

If command is given, the _all_labels function will be called
immediately with the same arguments. In simple cases this
makes it possible to perform the test for the tag and the
matching in one go. For example:

local expl ret=1
_tags foo bar baz
while _tags; do
_requested foo expl 'description' \
compadd foobar foobaz && ret=0
...
(( ret )) || break
done

If the command is not compadd, it must nevertheless be
prepared to handle the same options.

_retrieve_cache cache_identifier
This function retrieves completion information from the file
given by cache_identifier, stored in a directory specified by
the cache-path style which defaults to ~/.zcompcache. The
return status is zero if retrieval was successful. It will
only attempt retrieval if the use-cache style is set, so you
can call this function without worrying about whether the user
wanted to use the caching layer.

See _store_cache below for more details.

_sep_parts
This function is passed alternating arrays and separators as
arguments. The arrays specify completions for parts of
strings to be separated by the separators. The arrays may be
the names of array parameters or a quoted list of words in
parentheses. For example, with the array `hosts=(ftp news)'
the call `_sep_parts '(foo bar)' @ hosts' will complete the
string `f' to `foo' and the string `b@n' to `bar@news'.

This function accepts the compadd options `-V', `-J', `-1',
`-2', `-n', `-X', `-M', `-P', `-S', `-r', `-R', and `-q' and
passes them on to the compadd builtin used to add the matches.

_sequence [ -s sep ] [ -n max ] [ -d ] function [ - ] ...
This function is a wrapper to other functions for completing
items in a separated list. The same function is used to
complete each item in the list. The separator is specified
with the -s option. If -s is omitted it will use `,'.
Duplicate values are not matched unless -d is specified. If
there is a fixed or maximum number of items in the list, this
can be specified with the -n option.

Common compadd options are passed on to the function. It is
possible to use compadd directly with _sequence, though
_values may be more appropriate in this situation.

_setup tag [ group ]
This function sets up the special parameters used by the
completion system appropriately for the tag given as the first
argument. It uses the styles list-colors, list-packed,
list-rows-first, last-prompt, accept-exact, menu and
force-list.

The optional group supplies the name of the group in which the
matches will be placed. If it is not given, the tag is used
as the group name.

This function is called automatically from _description and
hence is not normally called explicitly.

_store_cache cache_identifier param ...
This function, together with _retrieve_cache and
_cache_invalid, implements a caching layer which can be used
in any completion function. Data obtained by costly
operations are stored in parameters; this function then dumps
the values of those parameters to a file. The data can then
be retrieved quickly from that file via _retrieve_cache, even
in different instances of the shell.

The cache_identifier specifies the file which the data should
be dumped to. The file is stored in a directory specified by
the cache-path style which defaults to ~/.zcompcache. The
remaining params arguments are the parameters to dump to the
file.

The return status is zero if storage was successful. The
function will only attempt storage if the use-cache style is
set, so you can call this function without worrying about
whether the user wanted to use the caching layer.

The completion function may avoid calling _retrieve_cache when
it already has the completion data available as parameters.
However, in that case it should call _cache_invalid to check
whether the data in the parameters and in the cache are still
valid.

See the _perl_modules completion function for a simple example
of the usage of the caching layer.

_tags [ [ -C name ] tag ... ]
If called with arguments, these are taken to be the names of
tags valid for completions in the current context. These tags
are stored internally and sorted by using the tag-order style.

Next, _tags is called repeatedly without arguments from the
same completion function. This successively selects the
first, second, etc. set of tags requested by the user. The
return status is zero if at least one of the tags is requested
and non-zero otherwise. To test if a particular tag is to be
tried, the _requested function should be called (see above).

If `-C name' is given, name is temporarily stored in the
argument field (the fifth) of the context in the curcontext
parameter during the call to _tags; the field is restored on
exit. This allows _tags to use a more specific context
without having to change and reset the curcontext parameter
(which has the same effect).

_tilde_files
Like _files, but resolve leading tildes according to the rules
of filename expansion, so the suggested completions don't
start with a `~' even if the filename on the command-line
does.

_values [ -O name ] [ -s sep ] [ -S sep ] [ -wC ] desc spec ...
This is used to complete arbitrary keywords (values) and their
arguments, or lists of such combinations.

If the first argument is the option `-O name', it will be used
in the same way as by the _arguments function. In other
words, the elements of the name array will be passed to
compadd when executing an action.

If the first argument (or the first argument after `-O name')
is `-s', the next argument is used as the character that
separates multiple values. This character is automatically
added after each value in an auto-removable fashion (see
below); all values completed by `_values -s' appear in the
same word on the command line, unlike completion using
_arguments. If this option is not present, only a single
value will be completed per word.

Normally, _values will only use the current word to determine
which values are already present on the command line and hence
are not to be completed again. If the -w option is given,
other arguments are examined as well.

The first non-option argument, desc, is used as a string to
print as a description before listing the values.

All other arguments describe the possible values and their
arguments in the same format used for the description of
options by the _arguments function (see above). The only
differences are that no minus or plus sign is required at the
beginning, values can have only one argument, and the forms of
action beginning with an equal sign are not supported.

The character separating a value from its argument can be set
using the option -S (like -s, followed by the character to use
as the separator in the next argument). By default the equals
sign will be used as the separator between values and
arguments.

Example:

_values -s , 'description' \
'*foo[bar]' \
'(two)*one[number]:first count:' \
'two[another number]::second count:(1 2 3)'

This describes three possible values: `foo', `one', and `two'.
The first is described as `bar', takes no argument and may
appear more than once. The second is described as `number',
may appear more than once, and takes one mandatory argument
described as `first count'; no action is specified, so it will
not be completed. The `(two)' at the beginning says that if
the value `one' is on the line, the value `two' will no longer
be considered a possible completion. Finally, the last value
(`two') is described as `another number' and takes an optional
argument described as `second count' for which the completions
(to appear after an `=') are `1', `2', and `3'. The _values
function will complete lists of these values separated by
commas.

Like _arguments, this function temporarily adds another
context name component to the arguments element (the fifth) of
the current context while executing the action. Here this
name is just the name of the value for which the argument is
completed.

The style verbose is used to decide if the descriptions for
the values (but not those for the arguments) should be
printed.

The associative array val_args is used to report values and
their arguments; this works similarly to the opt_args
associative array used by _arguments. Hence the function
calling _values should declare the local parameters state,
state_descr, line, context and val_args:

local context state state_descr line
typeset -A val_args

when using an action of the form `->string'. With this
function the context parameter will be set to the name of the
value whose argument is to be completed. Note that for
_values, the state and state_descr are scalars rather than
arrays. Only a single matching state is returned.

Note also that _values normally adds the character used as the
separator between values as an auto-removable suffix (similar
to a `/' after a directory). However, this is not possible
for a `->string' action as the matches for the argument are
generated by the calling function. To get the usual
behaviour, the calling function can add the separator x as a
suffix by passing the options `-qS x' either directly or
indirectly to compadd.

The option -C is treated in the same way as it is by
_arguments. In that case the parameter curcontext should be
made local instead of context (as described above).

_wanted [ -x ] [ -C name ] [ -12VJ ] tag name descr command [ arg
...] In many contexts, completion can only generate one particular
set of matches, usually corresponding to a single tag.
However, it is still necessary to decide whether the user
requires matches of this type. This function is useful in
such a case.

The arguments to _wanted are the same as those to _requested,
i.e. arguments to be passed to _description. However, in this
case the command is not optional; all the processing of tags,
including the loop over both tags and tag labels and the
generation of matches, is carried out automatically by
_wanted.

Hence to offer only one tag and immediately add the
corresponding matches with the given description:

local expl
_wanted tag expl 'description' \
compadd -- match1 match2...

See also the use of _wanted in the example function in the
subsection `Dynamic named directories' in zshexpn(1).

Note that, as for _requested, the command must be able to
accept options to be passed down to compadd.

Like _tags this function supports the -C option to give a
different name for the argument context field. The -x option
has the same meaning as for _description.

_widgets [ -g pattern ]
This function completes names of zle widgets (see the section
`Widgets' in zshzle(1)). The pattern, if present, is matched
against values of the $widgets special parameter, documented
in the section `The zsh/zleparameter Module' in zshmodules(1).

COMPLETION SYSTEM VARIABLES

There are some standard variables, initialised by the _main_complete
function and then used from other functions.

The standard variables are:

_comp_caller_options
The completion system uses setopt to set a number of options.
This allows functions to be written without concern for
compatibility with every possible combination of user options.
However, sometimes completion needs to know what the user's
option preferences are. These are saved in the
_comp_caller_options associative array. Option names, spelled
in lowercase without underscores, are mapped to one or other
of the strings `on' and `off'.

_comp_priv_prefix
Completion functions such as _sudo can set the
_comp_priv_prefix array to a command prefix that may then be
used by _call_program to match the privileges when calling
programs to generate matches.

Two more features are offered by the _main_complete function. The
arrays compprefuncs and comppostfuncs may contain names of functions
that are to be called immediately before or after completion has been
tried. A function will only be called once unless it explicitly
reinserts itself into the array.

COMPLETION DIRECTORIES

In the source distribution, the files are contained in various
subdirectories of the Completion directory. They may have been
installed in the same structure, or into one single function
directory. The following is a description of the files found in the
original directory structure. If you wish to alter an installed
file, you will need to copy it to some directory which appears
earlier in your fpath than the standard directory where it appears.

Base The core functions and special completion widgets
automatically bound to keys. You will certainly need most of
these, though will probably not need to alter them. Many of
these are documented above.

Zsh Functions for completing arguments of shell builtin commands
and utility functions for this. Some of these are also used
by functions from the Unix directory.

Unix Functions for completing arguments of external commands and
suites of commands. They may need modifying for your system,
although in many cases some attempt is made to decide which
version of a command is present. For example, completion for
the mount command tries to determine the system it is running
on, while completion for many other utilities try to decide
whether the GNU version of the command is in use, and hence
whether the --help option is supported.

X, AIX, BSD, ...
Completion and utility function for commands available only on
some systems. These are not arranged hierarchically, so, for
example, both the Linux and Debian directories, as well as the
X directory, may be useful on your system.

zsh 5.9 May 14, 2022 ZSHCOMPSYS(1)