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ZSHCOMPSYS(1)                                                    ZSHCOMPSYS(1)

       zshcompsys - zsh completion system

       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
       ?      an argument or option position: these describe the position on the command line at which  completion  is
              requested.  For example 'first argument to rmdir, the word being completed names a directory';

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

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

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

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

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

       When a completion is requested, a dispatcher function is called; see the description of _main_complete  in  the
       list of control functions below. This dispatcher decides which function should be called to produce the comple-
       tions, and calls it. The result is passed to one or more completers, functions that implement  individual  com-
       pletion 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:
       ?      those beginning 'comp' are to be called directly; there are only a few of these;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       For  incomplete  installations, if compinit does not find enough files beginning with an underscore (fewer than
       twenty) in the search path, it will try to find more by adding the directory _compdir to the search  path.   If
       that  directory  has  a subdirectory named Base, all subdirectories will be added to the path.  Furthermore, if
       the subdirectory Base has a subdirectory named Core, compinit will add all subdirectories of the subdirectories
       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... [ -[pP] patterns... [ -N 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.

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

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

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

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

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

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

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

       The # is part of the tag name and no white space is allowed after it.  The #compdef tags use the compdef  func-
       tion 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:

              The right hand side of an array-assignment ('foo=(...)')

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

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

              A word in command position

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

              Any word for which no other completion is defined

              A word beginning with an equals sign

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

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

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

              The word after a redirection operator.

              The contents of a parameter subscript.

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

              On the right hand side of an assignment.

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

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

       For the -redirect- context, the extra information is in the form '-redirect-,op,command', where op is the redi-
       rection 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.  In the
       case of elements of an associative array, for example 'assoc=(key <TAB>', name is expanded to  'name-key'.   In
       certain  special contexts, such as completing after 'make CFLAGS=', the command part gives the name of the com-
       mand, here make; otherwise it is empty.

       It is not necessary to define fully specific completions as the functions provided will try to generate comple-
       tions  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.


              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'.

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

       compdef [ -an ] function names... [ -[pP] patterns... [ -N names... ] ]
       compdef -d names...
       compdef -k [ -an ] function style key-sequences...
       compdef -K [ -an ] function name style key-sequences ...
              The first form defines the function to call for completion in the given contexts as  described  for  the
              #compdef tag above.

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

              The  function argument may alternatively be a string containing any shell code.  The string will be exe-
              cuted 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  overwrit-

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

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

              The  parameter  $_compskip  may be set by any function defined for a pattern context.  If it is set to a
              value containing the substring 'patterns' none of the pattern-functions will be called; if it is set  to
              a value containing the substring 'all', no other function will be called.

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

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

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

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

              compdef _pids foo

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

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

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

       When completion is attempted somewhere on the command line the completion system first works out  the  context.
       This  takes  account  of a number of things including the command word (such as 'grep' or 'zsh') and options to
       which the current word may be an argument (such as the '-o' option to zsh which takes  a  shell  option  as  an

       This context information is condensed into a string consisting of multiple fields separated by colons, referred
       to simply as 'the context' in the remainder of the documentation.  This is used to look up styles, context-sen-
       sitive  options that can be used to configure the completion system.  The context used for lookup may vary dur-
       ing the same call to the completion system.

       The context string always consists of a fixed set of fields, separated by  colons  and  with  a  leading  colon
       before  the  first,  in the form :completion:function:completer:command:argument:tag.  These have the following

       ?      The literal string completion, saying that this style is used by the completion  system.   This  distin-
              guishes the context from those used by, for example, zle widgets and ZFTP functions.

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

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

       ?      The command or a special -context-, just at it appears following the #compdef tag or the  compdef  func-
              tion.  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.

       ?      The argument; this indicates which command line or option argument we are completing.  For command argu-
              ments 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 com-
              pletions do not set this.

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

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


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

              dvips -o ...

       and the completion function will generate filenames.

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

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

       Styles determine such things as how the matches are generated, similarly to shell options but  with  much  more
       control.  They can have any number of strings as their value.  They are defined with the zstyle builtin command
       (see zshmodules(1)).

       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 may be matched as a pattern, and the name of
       the style itself, which must be given exactly.

       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 function.

       A  more  specific  example  of  the use of the verbose style is by the completion for the kill builtin.  If the
       style is set, the builtin lists full job texts and process command lines; otherwise it shows the bare job  num-
       bers 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 exam-
       ined 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::complete:foo' is more specific than  ':completion::complete:*'),  and
       longer patterns are preferred over shorter patterns.

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

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

              used to look up the users-hosts style

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

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

              for arguments to a command

       arrays for names of array parameters

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

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

              for names of builtin commands

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

              for X colormap ids

       colors for color names

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

              for contexts in arguments to the zstyle builtin command

              used by the _approximate and _correct completers for possible corrections

              for cursor names used by X programs

              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

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

              for names of device special files

              for names of directories

              for entries in the directory stack

              for X display names

              for network domains

              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

              for X server extensions

              for numbers of open file descriptors

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

       fonts  for X font names

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

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

              for filenames when the name has been generated by pattern matching

       groups for names of user groups

              for words from the history

       hosts  for hostnames

              for array indexes

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

              for network interfaces

              for names of zsh keymaps

              for names of X keysyms

              for names of system libraries

       limits for system limits

              for  names of directories that are subdirectories of the current working directory when completing argu-
              ments of cd and related builtin commands (compare path-directories)

              for names of manual pages

              for e-mail folders

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

              used to look up the format style for messages

              for names of X modifiers

              for modules (e.g. zsh modules)

              used to look up the users-hosts style

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

       names  for all kinds of names

              for USENET groups

              for nicknames of NIS maps

              for command options

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

              used to look up the users-hosts style

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

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

              for names of parameters

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

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

       pods   for perl pods (documentation files)

       ports  for communication ports

              for prefixes (like those of a URL)

              for print queue names

              for process identifiers

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

              for sequences (e.g. mh sequences)

              for sessions in the zftp function suite

              for signal names

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

       styles for styles used by the zstyle builtin command

              for filename extensions

       tags   for tags (e.g. rpm tags)

              for makefile targets

              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

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

              for X visuals

              used to look up the format style for warnings

              for zsh widget names

              for IDs of X windows

              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 control-
       ling completion listing such as list-packed and last-prompt).  When tested for the default tag, only the  func-
       tion  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 ...

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

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

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

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

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

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

              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.

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

              When  completing after an equals sign that is being treated as an assignment, the completion system nor-
              mally completes only one filename.  In some cases the value  may be a list  of  filenames  separated  by
              colons,  as  with PATH and similar parameters.  This style can be set to a list of patterns matching the
              names of such parameters.

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

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

              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

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

              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.

              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.

              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'.

              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  gener-
              ate 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 gener-
              ate the completion list.  Hence care should be taken to specify only commands that take a short time  to
              run, and in particular to avoid any that may never terminate.

              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.

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

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

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

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

              Each string may be either the name of a completer function or a string of the form 'function:name'.   In
              the  first  case  the  completer field of the context will contain the name of the completer without the
              leading underscore and with all other underscores replaced by hyphens.  In the second case the  function
              is  the  name  of  the completer to call, but the context will contain the user-defined name in the 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  'com-
              plete-foo'  in  the  completer  field of the context.  Normally, using the same completer more than once
              only makes sense when used with the 'functions:name' form, because otherwise the context  name  will  be
              the  same  in  all calls to the completer; possible exceptions to this rule are the _ignored and _prefix

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

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

              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 pre-
              ferred as the completion system may otherwise become confused.  The default list is :, +, /, -, %.   The
              list may be empty to force a delimiter to be typed.

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

              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.

              The  environ style is used when completing for 'sudo'.  It is set to an array of 'VAR=value' assignments
              to be exported into the local environment before the completion for the target command is invoked.
              zstyle :complete: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 pro-
              vided 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.

              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 argu-
              ments  of  cd.   The  tag named-directories-normal behaves as normal, but the tag named-directories-mine
              contains a fixed set of directories.  This has the effect of adding the match group 'extra  directories'
              with the given completions.

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

              This  style  is  used  when  completing  files  and looked up without a tag.  Its values are of the form
              'dir:names...'.  This will add the names (strings separated by spaces) as possible matches when complet-
              ing in the directory dir, even if no such files really exist.  The dir may be a pattern; pattern charac-
              ters 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.  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

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

              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 follow-
              ing code can be included in an initialization file:

                     zmodload -i zsh/stat
                     disable stat

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

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

                     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.

              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 con-
              sists 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 pre-
              ceded  by a backslash to make them distinguishable from the colon before the tag.  If more than one pat-
              tern is needed, the patterns can be given inside braces, separated by commas.

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

              The tag may also be followed by an optional second colon and a description, which will be used  for  the
              '%d'  in  the  value of the format style (if that is set) instead of the default description supplied by
              the completion function.  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 directo-
              ries, 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 effect, so  the  characters
              '#', '~' and '^' have special meanings in the patterns.

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

       filter This is used by the LDAP plugin for e-mail address completion to specify the attributes to match against
              when filtering entries.  So for example, if the style is set to 'sn', matching is done against surnames.
              Standard  LDAP  filtering  is used so normal completion matching is bypassed.  If this style is not set,
              the LDAP plugin is skipped.  You may also need to set the command style to specify  how  to  connect  to
              your LDAP server.

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

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

       format If  this is set for the descriptions tag, its value is used as a string to display above matches in com-
              pletion lists.  The sequence '%d' in this string will be replaced with a short description of what these
              matches  are.   This  string  may  also contain the following sequences to specify output attributes, as
              described in the section EXPANSION OF PROMPT SEQUENCES in zshmisc(1): '%B', '%S', '%U', '%F',  '%K'  and
              their  lower  case  counterparts,  as well as '%{...%}'.  '%F', '%K' and '%{...%}' take arguments in the
              same form as prompt expansion.  Note that the %G sequence is not available; an argument to  '%{'  should
              be used instead.

              The  style is tested with each tag valid for the current completion before it is tested for the descrip-
              tions 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  gener-
              ated at all.  In this case the '%d' is replaced with the descriptions for the matches that were expected
              separated by spaces.  The sequence '%D' is replaced with the same descriptions separated by newlines.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

              This is tested for each tag valid for the current completion.  If it is set to 'true', none of the words
              that are already on the line will be considered as possible completions.  If it is set to 'current', the
              word  the  cursor  is  on will not be considered as a possible completion.  The value 'current-shown' is
              similar but only applies if the list of completions is currently shown on the screen.  Finally,  if  the
              style is set to 'other', no word apart from the current one will be considered as a possible completion.

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

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

              The  style is tested without a tag by the function completing pathnames in order to determine whether to
              ignore the names of directories already mentioned in the current word, or the name of the current  work-
              ing 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 com-

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

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

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

                     Ignore the specified directories only when names of directories are completed, not when  complet-
                     ing 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.

              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'.

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

              Note  that  the EXTENDED_GLOB option is set during the execution of completion functions, so the charac-
              ters '#', '~' 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.

              When  completing  process IDs, for example as arguments to the kill and wait builtins the name of a com-
              mand 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 imme-
              diately to a set of possible IDs, and menu completion will be started to cycle through them.

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

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

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

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

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

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

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

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

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

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

              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 ':comple-

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

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

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

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

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

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

              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

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

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

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

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

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

              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.

              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.

              The value of this style is used in completion listing to separate the string to complete from a descrip-
              tion when possible (e.g. when completing options).  It defaults 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 directory name used by a user placing web pages  within  their
              home area.

              For example:

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

              Completion   after   'http://toast/stuff/'   will   look  for  files  in  the  directory  /var/http/pub-
              lic/toast/stuff,  while completion after 'http://toast/~yousir/' will look for files  in  the  directory

              If  set,  zsh  will  assume  that mailbox files can be found in the directory specified.  It defaults to

              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 gen-
              erate 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 '*'

              This style is tested separately for each tag valid in the current context.  Its value is  added  to  any
              match specifications given by the matcher-list style.  It should be in the form described in the section
              'Completion Matching Control' in zshcompwid(1).

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

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

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

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

              It  is  possible to create match specifications valid for particular completers by using the third field
              of the context.  For example, to use the completers _complete and _prefix but only  allow  case-insensi-
              tive completion with _complete:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

              If one of the values is explicitly set to false, menu completion will be explicitly turned off, overrid-
              ing the MENU_COMPLETE option and other settings.

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

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

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

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

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

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

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

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

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

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

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

              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; oth-
              erwise,  the standard completion list is generated; this is the default behaviour of _oldlist.  However,
              if there is an old list and this style contains the name of the completer function  that  generated  the
              list, then the old list will be used even if it was generated by a widget which does not do listing.

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

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

              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

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

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

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

              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  exam-
              ined  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.

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

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

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

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

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

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

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

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

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

              The default value for this style is 'false'.

              This,  too, is used 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.  In the case of command options, this means that the  initial
              '-', '+', or '--' must be typed explicitly before option names will be completed.

              The default value for this style is 'true'.

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

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

              If it is a singe 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 was been found, or max words have been tried.

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

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

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

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

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

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

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

              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  screen-
              ful minus the absolute value of the given number of lines.  The default is to scroll by single lines.

              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  sec-
              tion  number.   When  the  group-name style is also in effect, pages from different sections will appear
              separately.  This style is also used similarly with the words style when completing words for  the  dict
              command.  It  allows  words from different dictionary databases to be added separately.  The default for
              this style is 'false'.

              Tested whenever a new completer is tried.  If it is true, the completion system outputs a progress  mes-
              sage  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.

              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 origi-
              nal string are both added as matches and menu completion is started, making it easy to select either  of

       sort   Many  completion  widgets  call  _description  at some point which decides whether the matches are added
              sorted or unsorted (often indirectly via _wanted or _requested).  This style can be  set  explicitly  to
              one  of  the  usual true or false values as an override.  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.

              If  the  calling  widget  explicitly  requests unsorted matches, this is usually honoured.  However, the
              default (unsorted) behaviour of completion for the command history may  be  overridden  by  setting  the
              style to true.

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

              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=(..)'

              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.

              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.

              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'.

              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 some-
              thing like '~foo' or '$foo' rather than '~foo/' or '$foo/bar', unless that suffix itself contains  char-
              acters eligible for expansion.  The default for this style is 'true'.

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

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

              For example:

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

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

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

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

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

              tag:label ...
                     Here, tag is one of the standard tags and label is an arbitrary name.  Matches are  generated  as
                     normal but the name label is used in contexts instead of tag.  This is not useful in words start-
                     ing 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, supply-
                     ing different style settings for each attempt; see below for an example.

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

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

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

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

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

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

                     zstyle ':completion:*' tag-order \
                         'options:-long:long\ options
                          options:-short:short\ options
                          options:-single-letter:single\ letter\ options'

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

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

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

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

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

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

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

              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 spe-
              cial  inside completion widgets.  Setting reply to an empty array provides the default behaviour of try-
              ing all tags at once; setting it to an array containing only a hyphen disables the use of all  tags  and
              hence of all completions.

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

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

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

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

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

              For example,

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

              allows completion of all the components of the URL after suitable com-
              mands such as 'netscape' or 'lynx'.  Note, however, that access methods and files  are  completed  sepa-
              rately, so if the hosts style is set hosts can be completed without reference to the urls style.

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

              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.

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

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

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

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

              Various parts of the function system use awk to extract words from files or command output as it is uni-
              versally  available.  However, many versions of awk have arbitrary limits on the size of input.  If this
              style is set, perl will be used instead.  This is almost always preferable if perl is available on  your

              Currently  this  is  only  used in completions for 'make', but it may be extended depending on authorial

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

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

              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.

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

              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  comple-
              tion 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.

       The initialization script compinit redefines all the widgets which perform completion to call the supplied wid-
       get  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  func-
       tions  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

              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_com-
       plete  function  uses  the  return  status  of  the completer functions to decide if other completers should be
       called.  If the return status is zero, no other completers are tried and the _main_complete function returns.

       If the first argument to _main_complete is a single hyphen, the arguments will not be taken as  names  of  com-
       pleters.   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

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

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

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

              Note  that this does not generate completions by itself:  first use any of the standard ways of generat-
              ing 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.

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

                     zstyle ':completion:*' completer _complete _approximate

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

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

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

              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
                         reply=(_complete _match _prefix)
                         reply=(_ignored _correct _approximate)

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

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

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

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

              Finally, if 'compcontext' is set to a string without colons, the value is taken as the name of the  con-
              text to use and the function defined for that context will be called.  For this purpose, there is a spe-
              cial 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.

              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 simi-
              lar to spell-checking.  It is based on _approximate, but the completer field in the context name is cor-

              For example, with:

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

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

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

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

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

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

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

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

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

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

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

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

              The  ignored-patterns style can be set to a list of patterns which are compared against possible comple-
              tions; 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 com-
              pleters are invoked is determined in the same way as for  the  _prefix  completer.   The  single-ignored
              style is also available as described above.

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

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

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

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

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

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

              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 gener-
              ated,  instead of producing a new list of ordinary contextual completions.  It should appear in the list
              of completers before any of the widgets which generate  matches.   It  uses  two  styles:  old-list  and
              old-menu, see the section 'Completion System Configuration' above.

              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  simi-
              lar to the expand-or-complete-prefix command.

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

              For example, consider this global completer style:

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

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

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

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

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

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

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

              The  expansion  depends  on  the array style user-expand being defined for the current context; remember
              that the context for completers is less specific than that for contextual completion as the full context
              has not yet been determined.  Elements of the array may have one of the following forms:
              $hash    hash is the name of an associative array.  Note this is not a full parameter expression, merely
                     a $, suitably quoted to prevent immediate expansion, followed  by  the  name  of  an  associative
                     array.   If the trial expansion word matches a key in hash, the resulting expansion is the corre-
                     sponding 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.   The
                     return status of the function is irrelevant.

       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 follow-
       ing is a list of these and their default bindings.

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

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

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

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

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

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

              When used as a bindable command there is one additional feature that can be selected by setting the com-
              plete 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'.

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

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

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

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

       _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 com-
              pletion, if any, is always unique.

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

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

              Second, any other string will be passed as a set of arguments to compadd and should hence be an  expres-
              sion 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 accor-
              dance with standard shell rules.

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

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

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

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

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

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

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

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

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

              For example, after executing the following:

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

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

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

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

       Two  more  features  are offered by the _main_complete function.  The arrays compprefuncs and comppostfuncs may
       contain names of functions that are to be called immediately before or after  completion  has  been  tried.   A
       function will only be called once unless it explicitly reinserts itself into the array.

       _all_labels [ -x ] [ -12VJ ] tag name descr [ command args ... ]
              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.  Nor-
              mally, they are put directly after the command, but if one of the args is  a  single  hyphen,  they  are
              inserted directly before that.  If the hyphen is the last argument, it will be removed from the argument
              list before the command is called.  This allows _all_labels to be used in almost  all  cases  where  the
              matches  can  be  generated  by  a single call to the compadd builtin command or by a call to one of the
              utility functions.

              For example:

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

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

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

              The tags to use and the action to perform if a tag is requested are described using the specs which  are
              of  the  form:  'tag:descr:action'.   The  tags are offered using _tags and if the tag is requested, the
              action is executed with the given description descr.  The actions are those accepted by  the  _arguments
              function (described below), excluding the '->state' and '=...' forms.

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

                     _alternative \
                         'users:user:_users' \

              offers usernames and hostnames as possible matches, generated by the _users and _hosts functions respec-

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

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

       _arguments [ -nswWACRS ] [ -O name ] [ -M matchspec ] [ : ] spec ...
              This  function can be used to give a complete specification for completion for a command whose arguments
              follow standard UNIX option and argument conventions.  The following forms specify  individual  sets  of
              options  and arguments; to avoid ambiguity, these may be separated from the options to _arguments itself
              by a single colon.  Options to _arguments itself must be in separate words, i.e. -s -w, not -sw.

              With the option -n, _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.

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

                     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.

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

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

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

                     By  default,  options  are multi-character name, one '-word' per option.  With -s, options may be
                     single characters, with more than one option per word, although words starting with two  hyphens,
                     such  as  '--prefix',  are still considered complete option names.  This is suitable for standard
                     GNU options.

                     The combination of -s with -w allows single-letter options to be combined in a single  word  even
                     if  one  or more of the options take arguments.  For example, if -a takes an argument, with no -s
                     '-ab' is considered as a single (unhandled) option; with -s -ab is an option  with  the  argument
                     'b';  with  both  -s  and  -w, -ab may be the option -a and the option -b with arguments still to

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

                     The  following  forms  are available for the initial optspec, whether or not the option has argu-

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

                             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 sepa-
                             rate 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

                             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'.

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

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

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

                             An explanation string may be appended to any of the preceding forms of optspec by enclos-
                             ing 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:

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

                     This  group  may  be  repeated  for options which take multiple arguments.  In other words, :mes-
                     sage1:action1:message2:action2 specifies that the option takes two arguments.

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

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

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

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

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

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

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

       The forms for action are as follows.

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

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

                     :foo:(foo bar baz)

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

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

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

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

              Where  _arguments encounters a '->string', it will strip all leading and trailing whitespace from string
              and set the array state to the set of all stringss for which an action is to be performed.

              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, _argu-
              ments will instead return a status of 300 to indicate that $state is to be handled.

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

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

                     local context state line
                     typeset -A opt_args

              to prevent _arguments from altering the global environment.

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

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

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

              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 particu-
              lar  the  descriptions  of  options and arguments, is correctly passed to the completion command.  These
              additional arguments are taken from the array parameter 'expl'; this will be set up before executing the
              action  and  hence  may be referred to inside it, typically in an expansion of the form '$expl[@]' which
              preserves empty elements of the array.

       During the performance of the action the array 'line' will be set to the command name and normal arguments from
       the  command line, i.e. the words from the command line excluding all options and their arguments.  Options are
       stored in the associative array 'opt_args' with option names as keys and their arguments as  the  values.   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.

       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  com-
       pleting  the  argument  of  the  -o option, the name is 'option-o-1', while for the second normal (non-option-)
       argument it is 'argument-2'.

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

       It  is  possible  to  specify multiple sets of options and arguments with the sets separated by single hyphens.
       The specifications before the first hyphen (if any) are shared by all the remaining sets.  The  first  word  in
       every other set provides a name for the set which may appear in exclusion lists in specifications, either alone
       or before one of the possible values described above.  In the second case a '-' should appear between this name
       and the remainder.

       For example:

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

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

       If  the name given for one of the mutually exclusive sets is of the form '(name)' then only one value from each
       set will ever be completed; more formally, all specifications are mutually exclusive to  all  other  specifica-
       tions  in  the same set.  This is useful for defining multiple sets of options which are mutually exclusive and
       in which the options are aliases for each other.  For example:

              _arguments \
                  -a -b \
                - '(compress)' \
                  {-c,--compress}'[compress]' \
                - '(uncompress)' \

       As the completion code has to parse the command line separately for each set this form of argument is slow  and
       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 defi-

       The  options  -S and -A are available to simplify the specifications for commands with standard option parsing.
       With -S, no option will be completed after a '--' appearing on its own on the line; this argument  will  other-
       wise be ignored; hence in the line

              foobar -a -- -b

       the  '-a'  is  considered  an option but the '-b' is considered an argument, while the '--' is considered to be

       With -A, no options will be completed after the first non-option argument on the line.  The -A must be followed
       by a pattern matching all strings which are not to be taken as arguments.  For example, to make _arguments stop
       completing options after the first normal argument, but ignoring all strings starting with  a  hyphen  even  if
       they are not described by one of the optspecs, the form is '-A "-*"'.

       The  option  '-O  name'  specifies the name of an array whose elements will be passed as arguments to functions
       called to execute actions.  For example, this can be used to pass the same  set  of  options  for  the  compadd
       builtin to all actions.

       The  option  '-M spec' sets a match specification to use to completion option names and values.  It must appear
       before the first argument specification.  The default is 'r:|[_-]=* r:|=*': this allows partial word completion
       after '_' and '-', for example '-f-b' can be completed to '-foo-bar'.

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

              local curcontext="$curcontext"

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

       The option '--' allows _arguments to work out the names of long options that support the '--help' option  which
       is  standard  in many GNU commands.  The command word is called with the argument '--help' and the output exam-
       ined 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  specifiers  of  the  form 'pattern:message:action'; note that normal _arguments specifiers 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.  For example:

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

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

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

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

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

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

       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 \

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

       The '_arguments --' form can also be followed by the option '-s pair' to describe option  aliases.   Each  pair
       consists  of  a  pattern  and  a  replacement.   For  example,  some configure-scripts describe options only as
       '--enable-foo', but also accept '--disable-foo'.  To allow completion of the second form:

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

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

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

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

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

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

       The last two descriptions say what should be completed as arguments.  The first describes the first argument as
       a 'postscript file' and makes files ending in 'ps' or 'eps' be completed.  The last description gives all other
       arguments the description 'page 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_caching_policy () {
                         # rebuild if cache is more than a week old
                         local -a oldp
                         oldp=( "$1"(Nmw+1) )
                         (( $#oldp ))

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

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

       _call_program 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  exe-
              cute.   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.

       _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

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

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

              The matches generated will be taken from the value of the style.  These should contain the possible val-
              ues  for the combinations in the appropriate order (users, hosts, ports in the example above).  The dif-
              ferent fields the values for the different fields are separated by colons.  This can be altered with the
              option  -s to _combination which specifies a pattern.  Typically this is a character class, as for exam-
              ple '-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.

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

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

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

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

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

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

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

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

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

              The string returned by the format style (if any) will be modified so that the sequence '%d' is  replaced
              by  the descr given as the third argument without any leading or trailing white space.  If, after remov-
              ing 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  displayed  even  if  there  are  no  corresponding

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

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

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

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

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

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

       _files The function _files calls _path_files with all the arguments it was passed except for -g  and  -/.   The
              use of these two options depends on the setting of the  file-patterns style.

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

              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 is intended to be used in the action for the specifications passed to _arguments and simi-
              lar functions.  It returns immediately with a non-zero return status if the string to be completed  does
              not match the pattern.  If the pattern matches, the descr is displayed; the function then returns status
              zero if the word to complete is not empty, non-zero otherwise.

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

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

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

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

       _message [ -r12 ] [ -VJ group ] descr
       _message -e [ tag ] descr
              The  descr  is  used in the same way as the third argument to the _description function, except that the
              resulting string will always be shown whether or not matches were generated.  This is  useful  for  dis-
              playing 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.

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

              The  second  form  gives a description for completions with the tag tag to be shown even if there are no
              matches for that tag.  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.

       _multi_parts 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  pos-
              sible  completions  are  the  strings from the array.  However, each chunk delimited by sep will be com-
              pleted separately.  For example, the _tar function uses '_multi_parts / patharray' to  complete  partial
              file paths from the given array of complete file paths.

              The  -i option causes _multi_parts to insert a unique match even if that requires multiple separators to
              be inserted.  This is not usually the expected behaviour with filenames, but certain other types of com-
              pletion, 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 [ options ... ]
              This function is used to implement the loop over different tag labels for a particular tag as  described
              above for the tag-order style.  On each call it checks to see if there are any more tag labels; if there
              is it returns status zero, otherwise non-zero.  As this function requires a current tag to  be  set,  it
              must always follow a call to _tags or _requested.

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

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

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

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

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

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

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

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

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

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

              This is used to complete the names of shell parameters.

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

              All other arguments are passed to the compadd builtin.

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

              The options accepted by both _path_files and _files are:

              -f     Complete all filenames.  This is the default.

              -/     Specifies that only directories should be completed.

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

              -W paths
                     Specifies path prefixes that are to be prepended to the string from the command line to  generate
                     the  filenames  but  that should not be inserted as completions nor shown in completion listings.
                     Here, paths may be the name of an array parameter, a literal list of paths enclosed in  parenthe-
                     ses 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 [ -c command ] [ -r name ] label=pattern ... label [ args ... ]
              This  function  is used to resolve situations where a single command name requires more than one type of
              handling, either because it has more than one variant or because there is a name clash between two  dif-
              ferent 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 args  ...'  contains  pattern,
              then  label  is selected as the label for the command variant.  If none of the patterns match, the final
              command label is selected and status 1 is returned.

              If the '-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

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

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

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

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

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

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

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

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

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

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

              spec # This allows any number of repetitions of spec.

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

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

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


                     _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 com-
              ponent 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  com-
              pleted  as  aaa  and  even  arguments  as bbb.  Completion fails unless the set of aaa and bbb arguments
              before the current one is matched correctly.

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

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

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

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

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

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

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

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

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

              For example:

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

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

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

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

              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

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

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

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

              See _store_cache below for more details.

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

              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.

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

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

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

       _store_cache cache_identifier params ...
              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 argu-
              ments are the parameters to dump to the file.

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

              The completion function may avoid calling _retrieve_cache when it already has the completion data avail-
              able  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 ] tags ... ]
              If called with arguments, these are taken to be the names of tags valid for completions in  the  current
              context.  These tags are stored internally and sorted by using the tag-order style.

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

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

       _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

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

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

              The first non-option argument is used as a string to print as a description before listing the values.

              All other arguments describe the possible values and their arguments in the same  format  used  for  the
              description  of  options by the _arguments function (see above).  The only differences are that no minus
              or plus sign is required at the beginning, values can have only one argument, and the  forms  of  action
              beginning with an equal sign are not supported.

              The  character separating a value from its argument can be set using the option -S (like -s, followed by
              the character to use as the separator in the next argument).  By default the equals sign will be used as
              the separator between values and arguments.


                     _values -s , 'description' \
                             '*foo[bar]' \
                             '(two)*one[number]:first count:' \
                             'two[another number]::second count:(1 2 3)'

              This  describes  three possible values: 'foo', 'one', and 'two'.  The first is described as 'bar', takes
              no argument and may appear more than once.  The second is described as 'number', may  appear  more  than
              once,  and  takes  one mandatory argument described as 'first count'; no action is specified, so it will
              not be completed.  The '(two)' at the beginning says that if the value 'one' is on the line,  the  value
              'two'  will no longer be considered a possible completion.  Finally, the last value ('two') is described
              as 'another number' and takes an optional argument described as 'second count' for which the completions
              (to  appear after an '=') are '1', '2', and '3'.  The _values function will complete lists of these val-
              ues separated by commas.

              Like _arguments, this function temporarily adds another context name component to the arguments  element
              (the  fifth)  of the current context while executing the action.  Here this name is just the name of the
              value for which the argument is completed.

              The style verbose is used to decide if the descriptions for the values (but not those for the arguments)
              should be printed.

              The associative array val_args is used to report values and their arguments; this works similarly to the
              opt_args associative array used by _arguments.  Hence the function calling _values  should  declare  the
              local parameters state, line, context and val_args:

                     local context state line
                     typeset -A val_args

              when  using  an  action of the form '->string'.  With this function the context parameter will be set to
              the name of the value whose argument is to be completed.

              Note 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  the  calling function can add the separator x as a suffix by passing the options
              '-qS x' either directly or indirectly to compadd.

              The option -C is treated in the same way as it is by _arguments.  In that case the parameter  curcontext
              should be made local instead of context (as described above).

       _wanted [ -x ] [ -C name ]  [ -12VJ ] tag name descr command args ...
              In many contexts, completion can only generate one particular set of matches, usually corresponding to a
              single tag.  However, it is still necessary to decide whether the user requires matches  of  this  type.
              This function is useful in such a case.

              The  arguments  to _wanted are the same as those to _requested, i.e. arguments to be passed to _descrip-
              tion.  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

              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.

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

       Base   The  core functions and special completion widgets automatically bound to keys.  You will certainly need
              most of these, though will probably not need to alter them.  Many of these are documented above.

       Zsh    Functions for completing arguments of shell builtin commands and utility functions for  this.   Some  of
              these are also used by functions from the Unix directory.

       Unix   Functions for completing arguments of external commands and suites of commands.  They may need modifying
              for your system, although in many cases some attempt is made to decide which version  of  a  command  is
              present.   For example, completion for the mount command tries to determine the system it is running on,
              while completion for many other utilities try to decide whether the GNU version of  the  command  is  in
              use, and hence whether the --help option is supported.

       X, AIX, BSD, ...
              Completion  and  utility  function  for commands available only on some systems.  These are not arranged
              hierarchically, so, for example, both the Linux and Debian directories, as well as the X directory,  may
              be useful on your system.

zsh 4.3.11                     December 20, 2010                 ZSHCOMPSYS(1)