ZSHCOMPSYS(1) - phpMan

ZSHCOMPSYS(1) General Commands Manual 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 be-
ing 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 directo-
ries, 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 see
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 func-
tion 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 re-
ferred 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 compin-
stall, 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 re-
moved 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 au-
toloaded (`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 confirma-
tion.

Use of compinit
This section describes the use of compinit to initialize completion for the current ses-
sion 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 call-
ing 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 func-
tions 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 di-
rectories 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.

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 comple-
tion 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 sys-
tem. 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 specifica-
tions and functions written for bash.

Autoloaded files
The convention for autoloaded functions used in completion is that they start with an un-
derscore; 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 au-
tomatically contains the required directories for the standard functions.

For incomplete installations, if compinit does not find enough files beginning with an un-
derscore (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 distribu-
tion.

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 argu-
ments are to be completed or one of a number of special contexts in the form -con-
text- 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 func-
tions that can perform many different completions. It is implemented by setting
the parameter $service when calling the function; the function may choose to inter-
pret 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 respec-
tively. 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 op-
tions 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 re-
peated 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 comple-
tion 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=(...)')

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

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

-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 at-
tempted; a string containing the substring patterns: no pattern completion func-
tions 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 con-
text -context- is implemented by a corresponding function _context, for example the con-
text `-tilde-' and the function `_tilde').

The contexts -redirect- and -value- allow extra context-specific information. (Inter-
nally, 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 associa-
tive 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 de-
scribed 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 pat-
terns 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 pat-
tern-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-con-
text 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 func-
tion 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-com-
plete-prefix, list-choices, menu-complete, menu-expand-or-complete, and re-
verse-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 func-
tion, each of which requires the set of three arguments name, style and key-se-
quence, 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 com-
mands. 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 de-
tail 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 ac-
count of a number of things including the command word (such as `grep' or `zsh') and op-
tions 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 sepa-
rated by colons, referred to simply as `the context' in the remainder of the documenta-
tion. 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 com-
mand. 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:func-
tion: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 wid-
gets 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 wid-
gets 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 under-
score 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 be-
haviour 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 complet-
ing. 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 com-
pleter 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 comple-
tion at a particular point. This provides an easy way of finding information for tag-or-
der 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) style pattern, and the name of the style it-
self, which must be matched exactly. The following examples demonstrate that style pat-
terns may be loosely defined for styles that apply broadly, or as tightly defined as de-
sired 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 context 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 func-
tion.

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.
More precisely, strings are preferred over patterns (for example, `:completion::com-
plete:::foo' is more specific than `:completion::complete:::*'), and longer patterns are
preferred over shorter patterns.

A good rule of thumb is that any completion style pattern that needs to include more than
one wildcard (*) and that does not end in a tag name, should include all six colons (:),
possibly surrounding additional wildcards.

Style names like those of tags are arbitrary and depend on the completion function. How-
ever, 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 param-
eter 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 com-
pleting 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 argu-
ments 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 un-
derstand 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

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

interfaces
for network interfaces

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-directo-
ries) -- when the cdpath array is unset, directories is used instead

manuals
for names of manual pages

mailboxes
for e-mail folders

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 origi-
nal string as a match

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

other-files
for the names of any non-directory files. This is used instead of all-files when
the list-dirs-first style is in effect.

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 argu-
ments 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 kil-
lall

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 pa-
rameters 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 de-
fault, 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 com-
pletions 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 exam-
ple, the path /usr/bin/ is accepted immediately and completion tried in that direc-
tory.

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 am-
biguous 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 parame-
ters. This style can be set to a list of patterns matching the names of such pa-
rameters.

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 se-
quence `%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 spec-
ify 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 com-
pletion 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, match-
ing 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 com-
mon than completing options. Hence unless the value of this style is `true' op-
tions 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 under-
scores 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 com-
pleter 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 `func-
tions: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 with-
out 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 other-
wise 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 com-
pletion 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.

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-directo-
ries-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 spa-
ces) 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-ex-
act-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 param-
eter (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 con-
text. 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 `in-
sert' or `list', indicating that files are to be listed in long format in all cir-
cumstances, 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 distin-
guishable 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 look-
ing 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. If the description
given here contains itself a `%d', that is replaced with the description supplied
by the completion function.

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.

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

file-sort
The standard filename completion function uses this style without a tag to deter-
mine 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 ac-
cess 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 oppo-
site 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 use-
ful.

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 fil-
tering 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 sin-
gle match that will immediately be accepted. The style may also be set to a num-
ber. 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 cur-
rent 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 re-
placed with a short description of what these matches are. This string may also
contain the output attribute sequences understood by compadd -X (see zshcomp-
wid(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 de-
scriptions 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 es-
cape sequences. This is handled by the zformat builtin command from the zsh/zutil
module, see zshmodules(1).

glob This is used by the _expand completer. If it is set to `true' (the default), glob-
bing 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 sepa-
rate 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 dis-
played 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 -de-
fault-.

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 com-
pletions 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 com-
mands 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, al-
though 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 deter-
mined 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 possi-
ble 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 ac-
cept-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 comple-
tion of, for example, options multiple times even if the command in question ac-
cepts 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 cur-
rent 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 direc-
tory.

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 com-
pleted, 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.

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'.

ignored-patterns
A list of patterns; any trial completion matching one of the patterns will be ex-
cluded from consideration. The _ignored completer can appear in the list of com-
pleters 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 func-
tions, 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 possi-
ble 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-tab
If this is set to `true', the completion system will insert a TAB character (assum-
ing 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', com-
pletion 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 `pat-
tern'. Then the pattern on the line is left unchanged if it does not match unam-
biguously.

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.

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 exam-
ple, 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 un-
changed 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 un-
conditionally.

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.

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 cur-
rent completion, then the default tag. The cursor will be moved back to the previ-
ous line if this style is `true' for all types of match. Note that unlike the AL-
WAYS_LAST_PROMPT option this is independent of the numeric argument.

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.

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 specifi-
cations. This mechanism replaces the use of the ZLS_COLORS and ZLS_COLOURS parame-
ters 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. If set, directories to be completed are listed
separately from and before completion for other files, regardless of tag ordering.
In addition, the tag other-files is used in place of all-files for the remaining
files, to indicate that no directories are presented with that tag.

list-grouped
If this style is `true' (the default), the completion system will try to make cer-
tain 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 cy-
cle 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 nor-
mally.

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 zshmod-
ules(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 po-
sition 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 un-
derline, 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-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.

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 de-
faults to `--' (two hyphens).

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 di-
rectory 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 de-
scription of the tag-order style.

matcher-list
This style can be set to a list of match specifications that are to be applied ev-
erywhere. 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 specifica-
tion 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 over-
ride 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 correc-
tion, 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 speci-
fications 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. How-
ever, any matcher must explicitly specify case-insensitive matching if that is re-
quired.

For notes comparing the use of this and the matcher style, see under the descrip-
tion 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 exam-
ple, 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 gen-
erate corrected completions when given a numeric argument, so in this case the num-
ber 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 comple-
tion menu completion will be used. The value for a specific tag will take prece-
dence 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 explic-
itly 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 uncondi-
tionally.

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 `se-
lect=' 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 zsh-
modules(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 `~/.mut-
trc'.

numbers
This is used with the jobs tag. If it is `true', the shell will complete job num-
bers 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 com-
mand 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 gen-
erate 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 gener-
ated.

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 at-
tempt 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 un-
conditionally. 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 comple-
tion 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 com-
pletion 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 correc-
tions.

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 con-
tains 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 exam-
ple, /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 com-
ponent 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 de-
fault, 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 com-
mand 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 com-
pletion after `a:/...' and so on.

range This is used by the _history completer and the _history_complete_word bindable com-
mand 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 de-
limited unambiguously by including slashes on both sides. If an ordinary file com-
pletion 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_trTAB 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 posi-
tion. 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 com-
mands 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 connec-
tions 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 du-
plicates.

select-prompt
If this is set for the default tag, its value will be displayed during menu selec-
tion (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 `manual.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 sepa-
rately. 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 de-
fault of underlining is selected. The highlighting is only applied if the comple-
tion 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 chrono-
logically may be overridden by setting the style to `true'.

In the _expand completer, if it is set to `true', the expansions generated will al-
ways 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 con-
text 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 in-
stead 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 func-
tion. Spaces in the description must be quoted with a backslash. A `%d'
appearing in description is replaced with the description given by the com-
pletion 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 po-
sition 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 re-
placed 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, re-
stricting 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-insensi-
tive.

It is possible to use the -e option of the zstyle builtin command to specify condi-
tions 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 re-
ply 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 func-
tion 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 new-
lines).

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 de-
scend 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 com-
pleted 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 com-
mand. 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 de-
fined 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 spe-
cific 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 in-
voked 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 user-
names 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 prohibi-
tive 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 com-
plete usernames from this style (only), and will restrict subsequent hostname com-
pletion 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 com-
pleter 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 de-
scribed 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 stan-
dard 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 un-
dergo 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 er-
rors 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 comple-
tions 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 com-
pleter 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 _ig-
nored, _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 canon-
icalizing the paths given before using them for completion, in case they are al-
ready 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 appro-
priate 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 be-
haviour.

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 possi-
ble 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 _ap-
proximate, 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, correc-
tion 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 accept-
ing 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 gener-
ated 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 de-
tailed 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 contain-
ing all possible expansions, expansions when adding the possible expansions as sin-
gle 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-or-
der 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' be-
low.

_extensions
If the cursor follows the string `*.', filename extensions are completed. The ex-
tensions 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 Sys-
tem 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 deter-
mined 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 con-
dition 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, insert-
ing a `*' at the cursor position and comparing the resulting pattern with the pos-
sible 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-unam-
biguous 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 func-
tions (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 produc-
ing 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 com-
mand.

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 cur-
rent context is used -- except, of course, the _prefix completer itself. Further-
more, 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 com-
pleter after it, _prefix will be called a second time and, now only trying correc-
tion 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 in-
voked:

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; oth-
erwise, the cursor will be moved to the end of the current word before the comple-
tion code is called and hence there will be no suffix.

_user_expand
This completer behaves similarly to the _expand completer but instead performs ex-
pansions 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, fol-
lowed 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 expan-
sions. 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 bind-
ings.

_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; `$', en-
vironment 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 af-
ter 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, indepen-
dently 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 con-
trolled with the styles regular, global and disabled.

When used as a bindable command there is one additional feature that can be se-
lected 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 func-
tion field of the context and call the completion system. This allows custom com-
pletion widgets with their own set of style settings to be defined easily. For ex-
ample, to define a widget that performs normal completion and starts menu selec-
tion:

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, re-
move-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 argu-
ments will be called to generate the completions. Unambiguous parts of the func-
tion 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 comple-
tion functions used when completing at the current cursor position. If given a nu-
meric argument other than 1 (as in `ESC-2 ^Xh'), then the styles used and the con-
texts for which they are used will be shown, too.

Note that the information about styles may be incomplete; it depends on the infor-
mation 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 exe-
cuted, 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 _com-
plete_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 ar-
range that the next use of a generic widget run in the same shell will have the ef-
fect 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 func-
tions. 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 di-
rectly 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 com-
padd 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. Essen-
tially 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 descrip-
tion descr. The actions are those accepted by the _arguments function (described
below), excluding the `->state' and `=...' forms.

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 addi-
tional 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 execut-
ing 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 be-
ing 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 ana-
lyzed 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 sin-
gle-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 stack-
ing; 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 op-
tions 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 op-
tion 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 sin-
gle-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 argu-
ments. 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 exe-
cute actions. This is discussed in detail below.

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

specs: overview

Each of the following forms is a spec describing individual sets of options or ar-
guments 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 argu-
ment is optional. If the message contains only white space, nothing will be
printed above the matches unless the action adds an explanation string it-
self.

: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 begin-
ning 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 de-
scription.

optspec
optspec:...
This describes an option. The colon indicates handling for one or more ar-
guments 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 cur-
sor 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 exam-
ple, `-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 op-
tion 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 or-
dinary 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 op-
tion 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 ar-
guments: when the message is preceded by two colons, the words spe-
cial array and the CURRENT special parameter are modified during the
execution or evaluation of the action to refer only to the words af-
ter 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 back-
slash, `\:'.

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 com-
pleted 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 sin-
gle 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 com-
mand line, the list of remaining arguments (those shown in the above table begin-
ning 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 ar-
gument 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 re-
peatedly 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 gener-
ated. 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 ar-
ray 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 de-
sirable 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 ac-
tion 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 descrip-
tion style is set with the values tag in the context.

->string
In this form, _arguments processes the arguments and options and then re-
turns 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 re-
turn a status of 300 to indicate that $state is to be handled.

In addition to $state and $state_descr, _arguments also sets the global pa-
rameters `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), _argu-
ments 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 appro-
priate 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 descrip-
tions of options and arguments, is correctly passed to the completion com-
mand. 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 ar-
guments from the command line, i.e. the words from the command line after the com-
mand name excluding all options and their arguments. Options are stored in the as-
sociative array `opt_args' with option names as keys and their arguments as the
values. For options that have more than one argument these are given as one
string, separated by colons. All colons and backslashes in the original arguments
are preceded with backslashes.

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 param-
eter.

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 cur-
rent 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 associa-
tive 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 sep-
arated 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 con-
tains `-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 sup-
port 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 op-
tions 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 de-
scription 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 behav-
iour 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-FEA-
TURE' (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 corre-
sponding replacements, enclosed in parens and quoted so that it forms a single ar-
gument word in the _arguments call.

For example, some configure-script help output describes options only as `--en-
able-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 _ar-
guments with other functions, those functions should be called either before _argu-
ments, 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 ar-
guments. 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 de-
scribes 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 numbers' 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 argu-
ment 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 lo-
cale.

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 com-
mand-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 compo-
nent 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 con-
tain the possible values for the combinations in the appropriate order (users,
hosts, ports in the example above). The values for the different fields are sepa-
rated 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.

_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 fol-
lowed by options to pass to compadd. The array name1 contains the possible comple-
tions 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-hid-
den, 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 han-
dle 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 ap-
pear 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 tradition-
ally `expl', but this convention is not enforced). The description for the corre-
sponding 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 se-
quence `%d' is replaced by the descr given as the third argument without any lead-
ing 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 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 dis-
played 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 in-
cluded 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 en-
sures 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 han-
dle 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 comple-
tion 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 AT domain.tld addresses, without a name part or a com-
ment. 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 be-
low.

_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 op-
tions 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 fol-
lowed 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 func-
tion, 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 op-
tion 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 addi-
tional 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 ex-
ample, 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 partic-
ular 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 de-
termines if tag foo is required at all; the loop over _next_label handles any la-
bels 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 -con-
text-. 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 com-
mand, 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 _pre-
command, 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 parame-
ter _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.

_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 up-
per-case letters to match their lower-case counterparts (for example, `glob',
`noglob', `NO_GLOB' are all completed). Any arguments are propagated to the com-
padd builtin.

_options_set and _options_unset
These functions complete only set or unset options, with the same matching specifi-
cation 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 op-
tion 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 judi-
cious 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 com-
mand line to generate the filenames but that should not be inserted as com-
pletions 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 be-
cause 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 pat-
tern, 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_argu-
ments, 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 suc-
ceeds 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 pro-
ceeds 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 re-
maining 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 com-
bined 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 specifica-
tions 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 consid-
ered part of the completion target.

/pattern/- [%lookahead%] [-guard] [:tag:descr:action]
This is similar to `/pattern/ ...' but the actions of the current and previ-
ously 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 ar-
gument.

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 argu-
ments.

_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 argu-
ments 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 ar-
ray 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 argu-
ments, add and show. show takes no arguments, while the arguments for add have al-
ready 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 oth-
erwise. 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_identi-
fier, 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 parenthe-
ses. 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 appro-
priately 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 at-
tempt 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 comple-
tions 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 func-
tion. 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 expan-
sion, 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 ar-
gument 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, un-
like 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 al-
ready 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 argu-
ments.

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 de-
scribed 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 ac-
tion. Here this name is just the name of the value for which the argument is com-
pleted.

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 param-
eter 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 func-
tion can add the separator x as a suffix by passing the options `-qS x' either di-
rectly 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, usu-
ally 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 matches...

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 zsh-
zle(1)). The pattern, if present, is matched against values of the $widgets spe-
cial parameter, documented in the section `The zsh/zleparameter Module' in zshmod-
ules(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. Op-
tion 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 privi-
leges when calling programs to generate matches.

Two more features are offered by the _main_complete function. The arrays comppre-
funcs and comppostfuncs may contain names of functions that are to be called imme-
diately 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 Com-
pletion 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 di-
rectory 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 direc-
tories, as well as the X directory, may be useful on your system.

zsh 5.8.1 February 12, 2022 ZSHCOMPSYS(1)

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