Go to the first, previous, next, last section, table of contents.


Completion System

Description

This describes the shell code for the new completion system. It consists of various shell functions; those beginning `comp' are to be called directly by the user, while those beginning `_' are called by the completion code. The shell functions of the second set which implement completion behaviour and which may be bound to keystrokes, are referred to as `widgets'.

Note that with the function-based completions described here, it is also possible to use the `compctl -M ...' mechanism to specify global matching control, such as case-insensitivity (`abc' will complete to a string beginning `ABC'), or wildcard behaviour on certain anchors (`a-d' will complete to abc-def as if there were a `*' after the `a'). See section Matching Control for further details.

Initialization

The function compinstall can be run by a user to set up the completion system for use, which also provides options for more advanced usage. However, if the system was installed completely, it should be enough to call the shell function compinit from your initialization file; see the next section.

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

To run it, you will need to make sure it is in a directory mentioned in your $fpath parameter, and that it is autoloaded (`autoload -U compinstall' is recommended). It will ask you various questions about how you would like completion set up. It is in two parts; the basic part locates the completion files and decides where to put your personal dumpfile, used to speed up initialization after the first time. After that, you will be asked if you wish to go on to the advanced set-up; if you answer n, you can rerun compinstall later without having to re-enter any of the basic settings.

You can abort the installation any time you are being prompted for information, and your .zshrc will not be altered at all.

After initialization all the builtin completion widgets such as expand-or-complete will be redefined to use the new completion system. Should you need to, you can still bind keys to the old functions by putting a `.' in front, e.g. `.expand-or-complete'.

Use of compinit

This section describes the use of compinit to initialize completion for the current session when run directly by the user; 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 variable, and should be autoloaded (`autoload -U compinit' is recommended). When run, it will define a few utility functions, arrange for all the necessary shell functions to be autoloaded, and will then re-bind all keys that do completion to use the new system.

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

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

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

Autoloaded files

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

For incomplete installations, if compinit does not find enough files beginning with an underscore (fewer than twenty) in the search path, it will try to find more by adding the directory _compdir to the search path; if you have run compinstall, this will be set automatically. Furthermore, if the directory in question ends in the path segment Core, or has a subdirectory named Core, compinit will add all subdirectories of the directory where Core is to the path: this allows the functions to be in the same format as in the zsh source distribution.

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

The tags are:

#compdef names...
The file will be made autoloadable and the function defined in it will be called when completing names, each of which is either the name of a command whose arguments are to be completed or one of a number of special contexts in the form -context- described below for the _complete function.
#compdef -p pattern
The file will be made autoloadable and the function defined in it will be called when completing for a command whose name matches the given pattern (a standard globbing pattern). Note that only one pattern may be given.
#compdef -P pattern
Like the previous one, but the function will be called only if no completion function for the command on the line could be found.
#compdef -k style key-sequences...
This can be used to bind special completion functions to the key-sequences. It creates a widget behaving like the builtin widget style, which must be one of those 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 complist module is loaded (see section The complist Module), the menu-select widget can be used, too. If the option -n is also given, the bindings will not be used if the key is already bound (that is, is bound to something other than undefined-key). The widget is then bound to all the key-sequences given, if any: when one of the key-sequences is typed, the function in the file will be invoked to generate the matches. The widget created has the same name as the file and can also be bound to other keys using bindkey as usual.
#autoload
This is used for files defining utility function that are not to be called directly as completion functions but should be loaded automatically when invoked. Typically they are to be called from within one of the completion functions.

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

Functions

The compinit file defines the following functions, which may also be called directly by the user.

compdef [ -an ] function names...
compdef -d names...
compdef -p [ -a ] function pattern
compdef -P [ -a ] function pattern
compdef -k [ -a ] function style key-sequences...
The first form tells the completion system to call the given function when completing for the contexts or commands whose names are given: this is like the #compdef tag. If the -n option is given, any existing completion behaviour for particular contexts or commands will not be altered. These definitions can be deleted by giving the -d option as in the second form. The third form is similar to the first, but function will be called for all commands whose name matches the pattern; this is like the #compdef -p function tag. The fourth form is like the third, but the function will be called only if no function for the command itself was found or if one was found and it set the _compskip parameter to a value not containing the substring `patterns'. The fifth form defines a widget with the same name as the function which will be called for each of the key-sequences; this is like the #compdef -k tag. The function should generate the completions needed and will otherwise behave like the builtin widget whose name is given as the style argument. The widgets usable for this are: complete-word, delete-char-or-list, expand-or-complete, expand-or-complete-prefix, list-choices, menu-complete, menu-expand-or-complete, and reverse-menu-complete, as well as menu-select if the complist module is loaded. The option -n prevents the key being bound if it is already to bound to something other than undefined-key. In each of the forms supporting it the -a option makes the function autoloadable (exactly equivalent to autoload function).
compconf definitions...
compconf [ -L ]
compconf [ -l ] [ -L ] keys...
Several aspects of the completion system can be configured by the user. The configuration values are stored under the keys described below in the associative array `compconfig'. After sourcing compinit, configuration values can either be set directly as in `compconfig[completer]=_complete' or by calling this utility function. Each definition may be either a simple `key', which sets this key in the compconfig array to an empty string, or of the form `key=value' which stores the `value' under key `key'. Since the completion system also uses the array for internal purposes, you should not set all values at once by doing `compconfig=(...)'. In the second form (without arguments), this function lists all keys and their values. If given the -l option as its first argument, as in the last form, the other arguments are taken as names of keys and the values of these keys are printed one per line. In either case, if the -L option is given, the keys and values are printed as calls to this function, usable to be put in a setup script.
funcall return name [ args ... ]
If a function name exists, it is called with the arguments args. Unless it is the empty string or a single hyphen, return is taken as the name of a parameter and the return status from the called function is stored in it. The return value of funcall itself is zero if the function name exists and was called and non-zero otherwise.

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 colon-separated list in the configuration key completer. For example, to use normal completion and correction if that doesn't generate any matches:

compconf completer=_complete:_correct

after sourcing compinit. The default value for this configuration key set up in compinit is `_complete', i.e. normally only ordinary completion is tried. The _main_complete function uses the return value of the completer functions to decide if other completers should be called. If the return value is zero, no other completers are tried and the _main_complete function returns.

The widget function _main_complete also uses the configuration key last_prompt. If this is set to always, the cursor is moved up to the last prompt after printing a list of matches even if a numeric argument was given.

The following completer functions are contained in the distribution (users may write their own):

_complete
This completer generates all possible completions in a context-sensitive manner, i.e. using the compdef function explained above and the current settings of all special parameters. 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-, as mentioned above for the #compdef tag, are handled specially. These are:
-equal-
for completion after an equal sign, other than one occurring in a shell-variable assignment.
-tilde-
for completion after a tilde (`~') character, but before a slash.
-redirect-
for completion after a redirection operator.
-math-
for completion inside mathematical contexts, such as `((...))'.
-subscript-
for completion inside subscripts.
-value-
for completion on the right hand side of an assignment.
-array-value-
for completion on the right hand side of an array-assignment (`foo=(...)').
-condition-
for completion inside conditions (`[[...]]').
-parameter-
for completing the name of a parameter expansion (`$...').
-brace-parameter-
for completing the name of a parameter expansion within braces (`${...}').
-first-
for adding completions before any other other completion functions are tried (similar to the `-T' flag of compctl); if this function sets the _compskip parameter to `all', no other completion functions will be called, if it is set to a string containing `patterns', no pattern completion functions will be called, and if it is set to a string containing `default' the function for the `-default-' context will not be called, but functions defined for commands will.
-default-
for generating completions when no special completion function is used (similar to the `-D' option of compctl).
-command-
for completing in a command position (as with the `-C' option of compctl).
Default implementations are supplied for each of these contexts, in most cases named after the context itself (e.g. completion for the `-tilde-' context is done by the function named `_tilde'). Before trying to find a function for a specific context, _complete checks if the parameter `compcontext' is set to a non-empty value. If it is, the value is taken as the name of the context to use and the function defined for that context will be called.
_approximate
This completer function uses the _complete completer to generate a list of strings for the context the cursor is currently in, allowing you to specify a maximum number of errors: see the description of approximate matching in section Filename Generation for how errors are counted. The resulting list of corrected and completed strings is then presented to the user. The intended use of this completer function is to try after the normal _complete completer by setting:
compconf completer=_complete:_approximate
This will give correcting completion if and only if normal completion doesn't yield any possible completions. When corrected completions are found, the completer will normally start menucompletion allowing you to cycle through these strings. The exact behavior of this completer can be changed by using the following configuration keys:
approximate_accept
This should be set to the number of errors the correction code should accept. The completer will try to generate completions by first allowing one error, then two errors, and so on, until either a match was found or the maximum number of errors given by this key has been reached. If the value for this key contains a lower- or upper-case `n', the completer function will take any numeric argument as the maximum number of errors allowed. For example, with
compconf approximate_accept=2n
two errors will be allowed if no numeric argument is given. However, with a numeric argument of six (as in `ESC-6 TAB'), up to six errors are accepted. Hence with a value of `0n', no correcting completion will be attempted unless a numeric argument is given. If the value contains `n' or `N' and an exclamation mark (`!'), _approximate will not try to generate corrected completions when given a numeric argument, so in this case the number given should be greater than zero. For example, `2n!' specifies that correcting completion with two errors will usually be performed, but if a numeric argument is given, correcting completion will not be performed.
approximate_original
This key is used to specify whether the original string on which correcting completion was attempted is to be included in the list of possible corrections. If it is set to any non-empty string, the original string will be offered when cycling through the completions. Normally it will appear as the first string, so that the command line does not change immediately; consecutive completion attempts will cycle through the corrected strings. If the value for this key contains the substring `last', the original string will be the last one in the list, so that it appears just before wrapping around to the first corrected string again. Also, if the value contains the substring `always', the original string will always be included; normally it is included only if more than one possible correction was generated.
approximate_prompt
This can be set to a string to be displayed on top of the corrected strings generated when cycling through them. This string may contain the control sequences `%n', `%B', etc. known from the `-X' option of compctl. Also, the sequence `%e' will be replaced by the number of errors accepted to generate the corrected strings.
approximate_insert
If this is set to a string starting with `unambig', the code will try to insert a usable unambiguous string in the command line instead of always cycling through the corrected strings. If such a unambiguous string could be found, the original string is not used, independent of the setting of approximate_original. If no sensible string could be found, one can cycle through the corrected strings as usual.
If any of these keys is not set, but the the same key with the prefix `correct' instead of `approximate' is set, that value will be used. The forms beginning with `correct' are also used by the _correct completer function. The keys with the `approximate' prefix have no default values, but compinit defines default values for correct_accept (which is set to `2n'), and correct_prompt.
_correct
Generate corrections (but not completions) for the current word; this is similar to spell-checking. This calls _approximate, but only the configuration parameters beginning correct_ are used. For example, with:
compconf completer=_complete:_correct:_approximate
compconf correct_accept='2n!' approximate_accept=3n
correction will accept up to two errors. If a numeric argument is given, correction will not be performed, but correcting completion will be, and will accept as many errors as given by the numeric argument. Without a numeric argument, first correction and then correcting completion will be tried, with the first one accepting two errors and the second one accepting three errors. This completer function is intended to be used without the _approximate completer or, as in the example, just before it. Using it after the _approximate completer is useless since _approximate will at least generate the corrected strings generated by the _correct completer -- and probably more.
_match
This completer is intended to be used after the _complete completer. It allows one to give patterns on the command line and to complete all strings matching these patterns from the set of possible completions for the context the cursor is in, without having to set the GLOB_COMPLETE option. Normally this will be done by taking the pattern from the line, inserting a `*' at the cursor position and comparing the resulting pattern with the possible completions generated. However, if the configuration key match_original has a value of `only', no `*' will be inserted. If match_original has any other non-empty string as its value, this completer will first try to generate matches without, then with a `*' inserted at the cursor position. The generated matches will be offered in a menucompletion unless the match_insert configuration key is set to a string starting with `unambig'. In this case menucompletion will only be started if no unambiguous string could be generated that is at least as long as the original string.
_expand
This completer function does not really do completion, but instead checks if the word on the command line is eligible for expansion and, if it is, gives detailed control over how this expansion is done. When using this, one should not use the expand-or-complete widget, but instead use complete-word, as otherwise expand-or-complete will expand the string on the line before the completion widget is called. Also, this completer should be called before the _complete completer function. Control over how the expanded string will be treated is possible with the following configuration keys:
expand_substitute
If this is unset or set to the empty string, the code will first try to expand all substitutions in the string (such as `$(...)' and `${...}'). If this is set to an non-empty string it should be an expression usable inside a `$((...))' arithmetical expression. In this case, expansion of substitutions will be done if the expression evaluates to `1'. For example, with
compconf expand_substitute='${NUMERIC:-1} != 1'
substitution will be performed only if given an explicit numeric argument other than `1', as by typing `ESC 2 TAB'.
expand_glob
If this is unset or set to an empty string, globbing will be attempted on the word resulting from substitution or the original string. The values accepted for this key are the same as for expand_substitute.
expand_menu
If this is unset or set to the empty string, the words resulting from expansion (if any) will simply be inserted in the command line, replacing the original string. However, if this key is set to a non-empty string, the user can cycle through the expansion as in menucompletion. Unless the value contains the substring `only', the user will still be offered all expansions at once as one of the strings to insert in the command line; normally, this possibility is offered first, but if the value contains the substring `last', it is offered last. Finally, if the value contains the substring `sort', the expansions will be sorted alphabetically, normally they are kept in the order the expansion produced them in.
expand_original
If this is set to an non-empty string, the original string from the line will be included in the list of strings the user can cycle through as in a menucompletion. If the value contains the substring `last', the original string will appear as the last string, with other values it is inserted as the first one (so that the command line does not change immediately).
expand_prompt
This may be set to a string that should be displayed before the possible expansions. This is passed to the `-X' option of compadd and thus may contain the control sequences `%n', `%B', etc. Also, the sequence `%o' in this string will be replaced by the original string.
None of these configuration keys has a default value.
_list
This completer allows one to delay the insertion of matches 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. Configuration keys understood are:
list_condition
If this key is unset or set to the empty string, the insertion of matches will be delayed unconditionally. If this value is set, it should be set to an expression usable inside a `$((...))' arithmetical expression. In this case, delaying will be done if the expression evaluates to `1'. For example, with
compconf list_condition='NUMERIC != 1'
delaying will be done only if given an explicit numeric argument other than `1'.
list_word
To find out if listing should be performed on its own, the code normally compares the contents of the line with the contents the line had at the time of the last invocation. If this key is set to an non-empty string, comparison is done using only the current word. So if it is set, attempting completion on a word equal to the one when completion was called the last time will not delay the generation of matches.
_menu
This completer is a simple example function implemented to show how menucompletion can be done in shell code. It should be used as the first completer and has the effect of making the code perform menucompletion. Note that this is independent of the setting of the MENU_COMPLETE option and does not work with the other menucompletion 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 should appear in the list of completers before any of the widgets which generate matches. It understands two configuration keys:
oldlist_list
If this is set to always, then standard widgets which perform listing will retain the current list of matches, however they were generated. If it is set to never, this will not be done (the behaviour without the _oldlist completer). If it is unset, or any other value, then the existing list of completions will be displayed if it is not already; otherwise, the standard completion list will be generated: this is the default behaviour of _oldlist. However, if there is an old list and this key contains the name of the completer function that generated the list, then the old list will be used even if it was generated by a widget which does not do listing. For example, suppose you type ^Xc to use the _correct_word widget, which generates a list of corrections for the word under the cursor. Usually, typing ^D would generate a standard list of completions for the word on the command line, and show that. With _oldlist, it will instead show the list of corrections already generated. As another example consider the _match completer: with the match_insert key set to unambig it inserts only an unambiguous prefix string if there is any. But since this may remove parts of the original pattern, attempting completion again may result in more matches than on the first attempt. But by using the _oldlist completer and setting this key to _match, the list of matches generated on the first attempt will be used again.
oldlist_menu
Controls how menu completion behaves when a completion has already been inserted and the user types a standard completion key type such as TAB. The default behaviour of _oldlist is that menu completion always continues with the existing list of completions. If this key is set to never, however, a new completion is started if the old list was generated by a different completion command (the behaviour without the _oldlist completer). For example, suppose you type ^Xc to generate a list of corrections, and menu completion is started in one of the usual ways. Usually, typing TAB at this point would start trying to complete the line as it now appears. With _oldlist, it will instead continue to cycle through the list of completions.

Utility Functions

Descriptions follow for utility functions that may be useful when writing completion functions. Most of these reside in the Core subdirectory except where noted. Like the example functions for commands in the distribution, the utility functions generating matches all follow the convention of returning zero if they generated completions and non-zero if no matching completions could be added.

_compalso
This function looks up the definitions for the context and command names given as arguments and calls the handler functions for them if there is a definition (given with the compdef function). For example, the function completing inside subscripts might use `_compalso -math-' to include the completions generated for mathematical environments.
_normal
This function is used for normal command completion. If completion is attempted on the first word, command names are completed. Otherwise, the arguments are completed by calling the functions defined for this command, including those functions defined for patterns matching the command name. This function can also be called by other completion functions if they have to complete a range of words as a separate command. For example, the function to complete after the pre-command specifiers such as nohup removes the first word from the words array, decrements the CURRENT parameter, then calls this function. When calling a function defined for a pattern, this function also checks if the parameter _compskip is set and uses the value in the same way it is used after calling the completion function for the -first- context. With this one can write a pattern completion function that keeps other functions from being tried simply by setting this parameter to any value.
_description
This function gets two arguments: the name of an array and a string. It tests if the configuration key description_format is set and if it is, it stores some options in the array that can then be given to the compadd and compgen builtin commands to make the value of the description_format key (with the sequence `%d' replaced by the string given as the second argument) be displayed above the matches added. These options also will make sure that the matches are placed in a separate group (the second argument is used as the name of the group) if the configuration key group_matches is set to a non-empty string. Normally a sorted group will be used for this (with the `-J' option), but if the option `-V' is given, a unsorted group will be used instead. In most cases, this function will be used like this:
local expl
_description expl file
compadd "$expl[@]" - "$files[@]"
_message
This function takes one argument which is used like the second argument to the _description function. However, the resulting string will always be shown, not only if some matches were generated. This is useful to display help texts in places where no completions can be generated automatically. This function also uses the configuration key message_format in preference to description_format. The latter is used only if the former is unset or set to the empty string.
_display
This function generates a display list usable for the `-y' option of compadd and compgen. For this it takes its second argument as an array of possible matches with descriptions. The array may either be given as the name of an array parameter or directly as a list of words in parentheses. Each element of the array should contain a match, optionally followed by a colon and the description for this match. With this _display builds a string with one match and its description per line. Matches witout descriptions are appended at the end and aligned in multiple columns. After that, the first argument is taken as a parameter name and the string built is stored in it. Before the building the list, however, this function first uses compadd to remove all strings from the array that don't match the string on the line (so that they don't appear in the list). This means that the special parameters PREFIX and SUFFIX have to be set up correctly before this function is called. This call to compadd also uses the other arguments given to _display, by directly giving them to compadd. Finally, if the array is given as the name of a parameter, this paramete will be changed to include only those strings that match the string on the line. The return value of _display is zero if there was at least one matching string and the display string could be built and non-zero otherwise.
_multi_parts
This function gets two arguments: a separator character and an array. As usual, the array may be either the name of an array parameter or a literal array in the form `(foo bar)' (i.e. a list of words separated by white space in parentheses). With these arguments, this function will complete to strings from the array where the parts separated by the separator character are completed independently. For example, the _tar function from the distribution caches the pathnames from the tar file in an array and then calls this function to complete these names in the way normal filenames are completed by the _path_files function. Like other utility functions, this function accepts the `-V', `-J', and `-X' options with an argument and passes them to the compadd builtin.
_sep_parts
This function gets as arguments alternating arrays and separators. The arrays specify completions for parts of strings to be separated by the separators. The arrays may be the names of array parameters or a quoted list of words in parentheses. For example, with the array `hosts=(ftp news)' the call `_sep_parts '(foo bar)' @ hosts' will complete the string `f' to `foo' and the string `b@n' to `bar@news'. This function passes the `-V', `-J', and `-X' options and their arguments to the compadd builtin used to add the matches.
_path_files and _files
The function _path_files is used throughout the shell code to complete filenames. The advantage over the builtin completion functions is that 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 `-/', `-f', `-g', and `-W' are available as for the compctl and compgen builtins; -f is the default. Additionally, the `-F' option from the compadd builtin is supported, giving direct control over which filenames should be ignored as done by the fignore parameter in normal completion. The function _files calls _path_files with all the arguments it was passed and, if that generated no matches, calls _path_files again without any -g or -/ option, thus generating all filenames. These functions also accept the `-J', `-V', `-X', `-P', `-S', `-q', `-r', and `-R' options from the compadd builtin. Finally, the _path_files function supports two configuration keys.
path_expand
If this is set to any non-empty string, the partially typed path from the line will be expanded as far as possible even if trailing pathname components can not be completed.
path_cursor
If this is set to a non-empty string, the cursor will be left after the first ambiguous pathname component even when menucompletion is used.
_parameters
This should be used to complete parameter names if you need some of the extra options of compadd. All arguments are passed unchanged to the compadd builtin.
_options
This can be used to complete option names. The difference to the `-o' option of compgen is that this function uses a matching specification that ignores a leading `no', ignores underscores and allows the user to type upper-case letters, making them match their lower-case counterparts. All arguments passed to this function are propagated unchanged to the compgen builtin.
_set_options and _unset_options
These functions complete only set or unset options, with the same matching specification used in the _options function. Note that you need to uncomment a few lines in the _main_complete function for these functions to work properly. The lines in question are used to store the option settings in effect before the completion widget locally sets the options it needs.
_arguments
This function resides in the Base subdirectory of the example completion system because it is not used by the core system. This function can be used to complete words on the line by simply describing the arguments the command on the line gets. The description is given as arguments to this function, with each argument describing one option or normal argument of the command. The descriptions understood are:
n:message:action
This describes the n'th normal argument. The message will be printed above the matches generated and the action says what can be completed in this position (see below).
:message:action
Like the previous one, but describing the next argument. I.e. if you want to describe all arguments a command can get, you can leave out the numbers in the description and just use this form to describe them one after another in the order they have to appear on the line.
*:message:action
This describes how arguments are to be completed for which no description with one of the first two forms was given. This also means that any number of arguments can be completed. If there are two colons before the message (as in `*::message:action') the words special array and the CURRENT special parameter will be restricted to only the normal arguments when the action is executed or evaluated.
opt-spec[description ...]
This describes an option and (if at least one description is given) the arguments that have to come after the option. If no description is given, this will only be used to offer the option name as a possible completion in the right places. Each description has to be of the form `:message:action' or `::message:action', where the second form describes an optional argument and the first one describes a mandatory argument. The last description may also be of the form `:*:message:action' or `:*pattern:message:action'. These describe multiple arguments. In the first form all following words on the line are to be completed as described by the action, in the second form all words up to a word matching the given pattern are to be completed using the action. The `*' or the pattern may also be separated from the message by two or three colons. With two colons the words special array and the CURRENT special parameter are modified to refer only to the words after the option (with two colons) or to the words covered by this description (with three colons) during the execution or evaluation of the action. In the simplest form the opt-spec is just the option name beginning with a minus or a plus sign, such as `-foo'. In this case, the first argument for the option (if any) has to come as a separate word directly after the option and the option may appear only once on the line (and if it is already on the line, the option name will not be offered as a possible completion again). If the first argument for the option has to come directly after the option name in the same word, a minus sign should be added to the end of the opt-spec, as in `-foo-'. If the first argument may be given in one string with the option name, but may also be given as a separate argument after the option, a plus sign should be used instead. If the argument may be given as the next string or in same string as the option name but separated by it from an equal sign, a `=' should be used instead of the minus or plus sign. If the option may be given more than once, a star (`*') has to be added in front of the opt-spec because otherwise it is not offered as a possible completion again if it is already on the line. An opt-spec may also contain a list of other option names with which the option described is mutually exclusive. Such a list is given in parentheses at the beginning, as in `(-two -three)-one:...'. In this example, the options `-two' and `-three' will not be offered as possible completions if the option `-one' is on the line. Finally, the opt-spec may contain a explanation string. This is given in brackets at the end, as in `-q[query operation]'. The configuration key describe_options is used to decide if these explanation strings should be printed when options are listed. If it is set to a non-empty string and it doesn't contain the substring `!command', where `command' is the name of the command that is completed for, the descriptions will be shown.
In each of the cases above, the action says how the possible completions should be generated. In cases where only one of a fixed set of strings can be completed, these string can directly be given as a list in parentheses, as in `:foo:(foo bar baz)'. Such a list in doubled parentheses, as in `:foo:((a\:bar b\:baz))' should contain strings consisting of the string to complete followed by a colon (which needs to be preceded by a backslash) and a description. The matches will be listed together with their descriptions. A action of the form `->string' is used by functions that implement a state machine. In this case, the `string' (with all leading and trailing spaces and tabs removed) will be stored in the global parameter state and the function returns with a return value of one after setting the global `line' and `options' parameters as described below and without resetting any changes made to the special parameters such as PREFIX and words. A string in braces will be evaluated to generate the matches and if the action does not begin with an opening parentheses or brace, it will be split into separate words and executed. If the action starts with a space, this list of words will be invoked unchanged, otherwise it will be invoked with some extra string placed after the first word which can be given as arguments to the compadd and compgen builtins and which make sure that the message given in the description will be shown above the matches. To include a colon in the message or the action, it has to be preceded by a backslash. During the evaluation or execution of the action the array `line' will be set to the command name and normal arguments from the command line, i.e. to the words from the command line excluding all options and their arguments. These are stored in the associative array `options', using the 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 in the original arguments are preceded with backslashes. Normally the option names are taken as multi-character names and a word from the line is considered to contain only one option (or none). By giving the -s option to this function (as the first argument), options are considered to be one-character options and the strings from the line may contain more than one such option letter. The function can also be made to automatically complete long options for commands that support the `--help' option as, for example, most of the GNU commands do. For this, the string `--' must be given as one argument and if it is, the command from the line is invoked with the `--help' option and its output is parsed to find possible option names. Note that this means that you should be careful to make sure that this feature is not used for a command that does not support this option. For options that get an argument after a `=', the function also tries to automatically find out what should be completed as the argument. The possible completions for option-arguments can be described with the arguments after the `--' (which are not used as described above). Each argument contains one description of the form `pattern:message:action'. The message and the action have the same format as for the normal option descriptions described above. The action will be executed to complete arguments of options whose description in the output of the command from the line with the `--help' option matches the pattern. For example:
_arguments -- '*\*'     '(yes no)' \ 
              '*=FILE*' '_files' \ 
              '*=DIR*'  '_files -/'
Here, `yes' and `no' will be completed as the argument of options whose description ends in a star, file names for options that contain the substring `=FILE' in the description, and paths for options whose description contains `=DIR'. In fact, the last two patterns are not needed since this function always completes files for option descriptions containing `=FILE' and paths for option descriptions that contain `=DIR' or `=PATH'. These builtin patterns can be overridden by patterns given as arguments, however. Note also that _arguments tries to find out automatically if the argument for an option is optional. If it fails to automatically detect this, the colon before the message can be doubled to tell it about this as described for the normal option descriptions above. The option `-i patterns' (which must be given after the `--') can be used to give patterns for options which should not be completed. The patterns can be given as the name of an array parameter or as a literal list in parentheses. E.g. `-i "(--(en|dis)able-FEATURE*)"' will make the options `--enable-FEATURE' and `--disable-FEATURE' be ignored. The option `-s pairs' (again, after the `--') can be used to describe option aliases. Each pair consists of a pattern and a replacement. E.g. some configure-scripts describe options only as `--enable-foo', but also accept `disable-foo'. To allow completion of the second form, one would use `-s "(#--enable- --disable-)"'. Finally, this function uses the configuration key option_prefix. If it is set to a non-empty string, option names are added as possible matches only if the word on the line begins with the prefix character of them (i.e. a minus or a plus sign). If the value contains `!command' as a substring, where `command' is the name of the command that is completed for, the options are added as possible matches even if their prefix character is not given on the line. Example:
_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 one gets one argument described as `left border' for which no completion will be offered because of the empty action. The argument may come directly after the `-l' or it may be given as the next word on the line. The `-format' option gets one argument (in the next word) described as `paper size' for which only the strings `letter' and `A4' will be completed. The `-copy' option differs from the first two in that it may appear more than once on the command line and in that it accepts two arguments. The first one is mandatory and will be completed as a filename. The second one 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 one describes the first argument as a `postscript file' and makes files ending in `ps' or `eps' be completed. The last description says that all other arguments are `page numbers' but does not give possible completions.
_values
This is used to complete values (strings) and their arguments or lists of such values. If the first argument is the option `-s', the second argument is used as the character that separates multiple values. The first argument (after the option and separator character if they are given) 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 difference is that there is no required minus or plus sign at the beginning and that values can have only one argument. Example:
_values -s , '...' '*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 one is described as `bar', gets no argument and may appear more than once. The second one is described as `number', may appear more than once, and gets one mandatory argument described as `first count' for which no action is specified so that it will not be completed automatically. The `(one)' at the beginning says that if the value `one' is on the line, the value `two' will not be considered to be a possible completion any more. Finally, the last value (`two') is described as `another number' and gets an optional argument decribed as `second count' which will be completed from the strings `1', `2', and `3'. The _values function will complete lists of these values separated by commas. To decide if the descriptions for the values (not those for the arguments) should be printed, the configuration key describe_values is used in the same way as the key describe_options is used by the _arguments function.

Completion Directories

In the source distribution, the files are contained in various subdirectories of the Completion directory. They may have been installed in the same structure, or into one single function directory. The following is a description of the files found in the original directory structure. If you wish to alter an installed file, you will need to copy it to some directory which appears earlier in your fpath than the standard directory where it appears.

Core
The core scripts and functions. You will certainly need these, though will probably not need to alter them. Many of these are documented above.
Base
Other functions you will almost certainly want if you are going to use any of the standard completion functions. You may want to edit some of these files.
Builtins
Functions for completing arguments of shell builtin commands.
User
Functions for completing arguments of external commands and suites of commands. They may need modifying for your system.
Commands
Functions which implement special types of completion to be bound to keystrokes rather than called by context.

Bindable Commands

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

_correct_filename (^XC)
Correct the filename path at the cursor position. Allows up to six errors in the name. Can also be called with an argument to correct a filename path, independently of zle; the correction is printed on standard output.
_correct_word (^Xc)
Performs correction of the current argument using the usual contextual completions as possible choices.
_expand_word (^Xe)
Performs expansion on the current word: equivalent to the standard expand-word command, but using all the `expand_*' configuration keys described previously. In addition, each such key can be overridden by a key starting with the string `expandword_'; for example, the expandword_substitute key if defined overrides the expand_substitute key.
_history_complete_word (\e/)
Complete words from the shell's command history.
_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.
_read_comp (^X^R)
Prompt the user for a string, and use that to perform completion on the current word. There are two possibilities for the string. First, it can be a set of words beginning `_', for example `_files -/', in which case the function with any arguments will be called to generate the completions. Unambiguous parts of the function name will be completed automatically (normal completion is not available at this point) until a space is typed. Otherwise, any other string, for example `-b', will be passed as arguments to compgen and should hence be a set of flags specifying the type of completion. 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.


Go to the first, previous, next, last section, table of contents.