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* ZSH: (zsh).                     The Z Shell Manual.
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File: zsh.info,  Node: Completion Widgets,  Next: Completion System,  Prev: Zsh Line Editor,  Up: Top

19 Completion Widgets
*********************

19.1 Description
================

The shell's programmable completion mechanism can be manipulated in two
ways; here the low-level features supporting the newer, function-based
mechanism are defined.  A complete set of shell functions based on these
features is described in the next chapter, *note Completion System::,
and users with no interest in adding to that system (or, potentially,
writing their own -- see dictionary entry for 'hubris') should skip the
current section.  The older system based on the compctl builtin command
is described in *note Completion Using compctl::.

Completion widgets are defined by the -C option to the zle builtin
command provided by the zsh/zle module (see *note The zsh/zle Module::).
For example,

     zle -C complete expand-or-complete completer

defines a widget named 'complete'.  The second argument is the name of
any of the builtin widgets that handle completions: complete-word,
expand-or-complete, expand-or-complete-prefix, menu-complete,
menu-expand-or-complete, reverse-menu-complete, list-choices, or
delete-char-or-list.  Note that this will still work even if the widget
in question has been re-bound.

When this newly defined widget is bound to a key using the bindkey
builtin command defined in the zsh/zle module (*note Zsh Line Editor::),
typing that key will call the shell function 'completer'.  This function
is responsible for generating the possible matches using the builtins
described below.  As with other ZLE widgets, the function is called with
its standard input closed.

Once the function returns, the completion code takes over control again
and treats the matches in the same manner as the specified builtin
widget, in this case expand-or-complete.

* Menu:

* Completion Special Parameters::
* Completion Builtin Commands::
* Completion Condition Codes::
* Completion Matching Control::
* Completion Widget Example::


File: zsh.info,  Node: Completion Special Parameters,  Next: Completion Builtin Commands,  Up: Completion Widgets

19.2 Completion Special Parameters
==================================

The parameters ZLE_REMOVE_SUFFIX_CHARS and ZLE_SPACE_SUFFIX_CHARS are
used by the completion mechanism, but are not special.  See *note
Parameters Used By The Shell::.

Inside completion widgets, and any functions called from them, some
parameters have special meaning; outside these functions they are not
special to the shell in any way.  These parameters are used to pass
information between the completion code and the completion widget.  Some
of the builtin commands and the condition codes use or change the
current values of these parameters.  Any existing values will be hidden
during execution of completion widgets; except for compstate, the
parameters are reset on each function exit (including nested function
calls from within the completion widget) to the values they had when the
function was entered.

CURRENT
     This is the number of the current word, i.e.  the word the cursor
     is currently on in the words array.  Note that this value is only
     correct if the ksharrays option is not set.

IPREFIX
     Initially this will be set to the empty string.  This parameter
     functions like PREFIX; it contains a string which precedes the one
     in PREFIX and is not considered part of the list of matches.
     Typically, a string is transferred from the beginning of PREFIX to
     the end of IPREFIX, for example:

          IPREFIX=${PREFIX%%\=*}=
          PREFIX=${PREFIX#*=}

     causes the part of the prefix up to and including the first equal
     sign not to be treated as part of a matched string.  This can be
     done automatically by the compset builtin, see below.

ISUFFIX
     As IPREFIX, but for a suffix that should not be considered part of
     the matches; note that the ISUFFIX string follows the SUFFIX
     string.

PREFIX
     Initially this will be set to the part of the current word from the
     beginning of the word up to the position of the cursor; it may be
     altered to give a common prefix for all matches.

QIPREFIX
     This parameter is read-only and contains the quoted string up to
     the word being completed.  E.g.  when completing '"foo', this
     parameter contains the double quote.  If the -q option of compset
     is used (see below), and the original string was '"foo bar' with
     the cursor on the 'bar', this parameter contains '"foo '.

QISUFFIX
     Like QIPREFIX, but containing the suffix.

SUFFIX
     Initially this will be set to the part of the current word from the
     cursor position to the end; it may be altered to give a common
     suffix for all matches.  It is most useful when the option
     COMPLETE_IN_WORD is set, as otherwise the whole word on the command
     line is treated as a prefix.

compstate
     This is an associative array with various keys and values that the
     completion code uses to exchange information with the completion
     widget.  The keys are:

     all_quotes
          The -q option of the compset builtin command (see below)
          allows a quoted string to be broken into separate words; if
          the cursor is on one of those words, that word will be
          completed, possibly invoking 'compset -q' recursively.  With
          this key it is possible to test the types of quoted strings
          which are currently broken into parts in this fashion.  Its
          value contains one character for each quoting level.  The
          characters are a single quote or a double quote for strings
          quoted with these characters, a dollars sign for strings
          quoted with $'...' and a backslash for strings not starting
          with a quote character.  The first character in the value
          always corresponds to the innermost quoting level.

     context
          This will be set by the completion code to the overall context
          in which completion is attempted.  Possible values are:

          array_value
               when completing inside the value of an array parameter
               assignment; in this case the words array contains the
               words inside the parentheses.

          brace_parameter
               when completing the name of a parameter in a parameter
               expansion beginning with ${.  This context will also be
               set when completing parameter flags following ${(; the
               full command line argument is presented and the handler
               must test the value to be completed to ascertain that
               this is the case.

          assign_parameter
               when completing the name of a parameter in a parameter
               assignment.

          command
               when completing for a normal command (either in command
               position or for an argument of the command).

          condition
               when completing inside a '[[...]]'  conditional
               expression; in this case the words array contains only
               the words inside the conditional expression.

          math
               when completing in a mathematical environment such as a
               '((...))'  construct.

          parameter
               when completing the name of a parameter in a parameter
               expansion beginning with $ but not ${.

          redirect
               when completing after a redirection operator.

          subscript
               when completing inside a parameter subscript.

          value
               when completing the value of a parameter assignment.

     exact
          Controls the behaviour when the REC_EXACT option is set.  It
          will be set to accept if an exact match would be accepted, and
          will be unset otherwise.

          If it was set when at least one match equal to the string on
          the line was generated, the match is accepted.

     exact_string
          The string of an exact match if one was found, otherwise
          unset.

     ignored
          The number of words that were ignored because they matched one
          of the patterns given with the -F option to the compadd
          builtin command.

     insert
          This controls the manner in which a match is inserted into the
          command line.  On entry to the widget function, if it is unset
          the command line is not to be changed; if set to unambiguous,
          any prefix common to all matches is to be inserted; if set to
          automenu-unambiguous, the common prefix is to be inserted and
          the next invocation of the completion code may start menu
          completion (due to the AUTO_MENU option being set); if set to
          menu or automenu menu completion will be started for the
          matches currently generated (in the latter case this will
          happen because the AUTO_MENU is set).  The value may also
          contain the string 'tab' when the completion code would
          normally not really do completion, but only insert the TAB
          character.

          On exit it may be set to any of the values above (where
          setting it to the empty string is the same as unsetting it),
          or to a number, in which case the match whose number is given
          will be inserted into the command line.  Negative numbers
          count backward from the last match (with '-1' selecting the
          last match) and out-of-range values are wrapped around, so
          that a value of zero selects the last match and a value one
          more than the maximum selects the first.  Unless the value of
          this key ends in a space, the match is inserted as in a menu
          completion, i.e.  without automatically appending a space.

          Both menu and automenu may also specify the number of the
          match to insert, given after a colon.  For example, 'menu:2'
          says to start menu completion, beginning with the second
          match.

          Note that a value containing the substring 'tab' makes the
          matches generated be ignored and only the TAB be inserted.

          Finally, it may also be set to all, which makes all matches
          generated be inserted into the line.

     insert_positions
          When the completion system inserts an unambiguous string into
          the line, there may be multiple places where characters are
          missing or where the character inserted differs from at least
          one match.  The value of this key contains a colon separated
          list of all these positions, as indexes into the command line.

     last_prompt
          If this is set to a non-empty string for every match added,
          the completion code will move the cursor back to the previous
          prompt after the list of completions has been displayed.
          Initially this is set or unset according to the
          ALWAYS_LAST_PROMPT option.

     list
          This controls whether or how the list of matches will be
          displayed.  If it is unset or empty they will never be listed;
          if its value begins with list, they will always be listed; if
          it begins with autolist or ambiguous, they will be listed when
          the AUTO_LIST or LIST_AMBIGUOUS options respectively would
          normally cause them to be.

          If the substring force appears in the value, this makes the
          list be shown even if there is only one match.  Normally, the
          list would be shown only if there are at least two matches.

          The value contains the substring packed if the LIST_PACKED
          option is set.  If this substring is given for all matches
          added to a group, this group will show the LIST_PACKED
          behavior.  The same is done for the LIST_ROWS_FIRST option
          with the substring rows.

          Finally, if the value contains the string explanations, only
          the explanation strings, if any, will be listed and if it
          contains messages, only the messages (added with the -x option
          of compadd) will be listed.  If it contains both explanations
          and messages both kinds of explanation strings will be listed.
          It will be set appropriately on entry to a completion widget
          and may be changed there.

     list_lines
          This gives the number of lines that are needed to display the
          full list of completions.  Note that to calculate the total
          number of lines to display you need to add the number of lines
          needed for the command line to this value, this is available
          as the value of the BUFFERLINES special parameter.

     list_max
          Initially this is set to the value of the LISTMAX parameter.
          It may be set to any other value; when the widget exits this
          value will be used in the same way as the value of LISTMAX.

     nmatches
          The number of matches generated and accepted by the completion
          code so far.

     old_insert
          On entry to the widget this will be set to the number of the
          match of an old list of completions that is currently inserted
          into the command line.  If no match has been inserted, this is
          unset.

          As with old_list, the value of this key will only be used if
          it is the string keep.  If it was set to this value by the
          widget and there was an old match inserted into the command
          line, this match will be kept and if the value of the insert
          key specifies that another match should be inserted, this will
          be inserted after the old one.

     old_list
          This is set to yes if there is still a valid list of
          completions from a previous completion at the time the widget
          is invoked.  This will usually be the case if and only if the
          previous editing operation was a completion widget or one of
          the builtin completion functions.  If there is a valid list
          and it is also currently shown on the screen, the value of
          this key is shown.

          After the widget has exited the value of this key is only used
          if it was set to keep.  In this case the completion code will
          continue to use this old list.  If the widget generated new
          matches, they will not be used.

     parameter
          The name of the parameter when completing in a subscript or in
          the value of a parameter assignment.

     pattern_insert
          Normally this is set to menu, which specifies that menu
          completion will be used whenever a set of matches was
          generated using pattern matching.  If it is set to any other
          non-empty string by the user and menu completion is not
          selected by other option settings, the code will instead
          insert any common prefix for the generated matches as with
          normal completion.

     pattern_match
          Locally controls the behaviour given by the GLOB_COMPLETE
          option.  Initially it is set to '*' if and only if the option
          is set.  The completion widget may set it to this value, to an
          empty string (which has the same effect as unsetting it), or
          to any other non-empty string.  If it is non-empty, unquoted
          metacharacters on the command line will be treated as
          patterns; if it is '*', then additionally a wildcard '*' is
          assumed at the cursor position; if it is empty or unset,
          metacharacters will be treated literally.

          Note that the matcher specifications given to the compadd
          builtin command are not used if this is set to a non-empty
          string.

     quote
          When completing inside quotes, this contains the quotation
          character (i.e.  either a single quote, a double quote, or a
          backtick).  Otherwise it is unset.

     quoting
          When completing inside single quotes, this is set to the
          string single; inside double quotes, the string double; inside
          backticks, the string backtick.  Otherwise it is unset.

     redirect
          The redirection operator when completing in a redirection
          position, i.e.  one of <, >, etc.

     restore
          This is set to auto before a function is entered, which forces
          the special parameters mentioned above (words, CURRENT,
          PREFIX, IPREFIX, SUFFIX, and ISUFFIX) to be restored to their
          previous values when the function exits.  If a function unsets
          it or sets it to any other string, they will not be restored.

     to_end
          Specifies the occasions on which the cursor is moved to the
          end of a string when a match is inserted.  On entry to a
          widget function, it may be single if this will happen when a
          single unambiguous match was inserted or match if it will
          happen any time a match is inserted (for example, by menu
          completion; this is likely to be the effect of the
          ALWAYS_TO_END option).

          On exit, it may be set to single as above.  It may also be set
          to always, or to the empty string or unset; in those cases the
          cursor will be moved to the end of the string always or never
          respectively.  Any other string is treated as match.

     unambiguous
          This key is read-only and will always be set to the common
          (unambiguous) prefix the completion code has generated for all
          matches added so far.

     unambiguous_cursor
          This gives the position the cursor would be placed at if the
          common prefix in the unambiguous key were inserted, relative
          to the value of that key.  The cursor would be placed before
          the character whose index is given by this key.

     unambiguous_positions
          This contains all positions where characters in the
          unambiguous string are missing or where the character inserted
          differs from at least one of the matches.  The positions are
          given as indexes into the string given by the value of the
          unambiguous key.

     vared
          If completion is called while editing a line using the vared
          builtin, the value of this key is set to the name of the
          parameter given as an argument to vared.  This key is only set
          while a vared command is active.

words
     This array contains the words present on the command line currently
     being edited.


File: zsh.info,  Node: Completion Builtin Commands,  Next: Completion Condition Codes,  Prev: Completion Special Parameters,  Up: Completion Widgets

19.3 Completion Builtin Commands
================================

compadd [ -akqQfenUlo12C ] [ -F ARRAY ]
        [-P PREFIX ] [ -S SUFFIX ]
        [-p HIDDEN-PREFIX ] [ -s HIDDEN-SUFFIX ]
        [-i IGNORED-PREFIX ] [ -I IGNORED-SUFFIX ]
        [-W FILE-PREFIX ] [ -d ARRAY ]
        [-J NAME ] [ -V NAME ] [ -X EXPLANATION ] [ -x MESSAGE ]
        [-r REMOVE-CHARS ] [ -R REMOVE-FUNC ]
        [-D ARRAY ] [ -O ARRAY ] [ -A ARRAY ]
        [-E NUMBER ]
        [-M MATCH-SPEC ] [ -- ] [ WORDS ... ]

     This builtin command can be used to add matches directly and
     control all the information the completion code stores with each
     possible match.  The return status is zero if at least one match
     was added and non-zero if no matches were added.

     The completion code breaks the string to complete into seven fields
     in the order:

          <IPRE><APRE><HPRE><WORD><HSUF><ASUF><ISUF>

     The first field is an ignored prefix taken from the command line,
     the contents of the IPREFIX parameter plus the string given with
     the -i option.  With the -U option, only the string from the -i
     option is used.  The field <APRE> is an optional prefix string
     given with the -P option.  The <HPRE> field is a string that is
     considered part of the match but that should not be shown when
     listing completions, given with the -p option; for example,
     functions that do filename generation might specify a common path
     prefix this way.  <WORD> is the part of the match that should
     appear in the list of completions, i.e.  one of the WORDS given at
     the end of the compadd command line.  The suffixes <HSUF>, <ASUF>
     and <ISUF> correspond to the prefixes <HPRE>, <APRE> and <IPRE> and
     are given by the options -s, -S and -I, respectively.

     The supported flags are:

     -P PREFIX
          This gives a string to be inserted before the given WORDS.
          The string given is not considered as part of the match and
          any shell metacharacters in it will not be quoted when the
          string is inserted.

     -S SUFFIX
          Like -P, but gives a string to be inserted after the match.

     -p HIDDEN-PREFIX
          This gives a string that should be inserted into the command
          line before the match but that should not appear in the list
          of matches.  Unless the -U option is given, this string must
          be matched as part of the string on the command line.

     -s HIDDEN-SUFFIX
          Like '-p', but gives a string to insert after the match.

     -i IGNORED-PREFIX
          This gives a string to insert into the command line just
          before any string given with the '-P' option.  Without '-P'
          the string is inserted before the string given with '-p' or
          directly before the match.

     -I IGNORED-SUFFIX
          Like -i, but gives an ignored suffix.

     -a
          With this flag the WORDS are taken as names of arrays and the
          possible matches are their values.  If only some elements of
          the arrays are needed, the WORDS may also contain subscripts,
          as in 'foo[2,-1]'.

     -k
          With this flag the WORDS are taken as names of associative
          arrays and the possible matches are their keys.  As for -a,
          the WORDS may also contain subscripts, as in 'foo[(R)*bar*]'.

     -d ARRAY
          This adds per-match display strings.  The ARRAY should contain
          one element per WORD given.  The completion code will then
          display the first element instead of the first WORD, and so
          on.  The ARRAY may be given as the name of an array parameter
          or directly as a space-separated list of words in parentheses.

          If there are fewer display strings than WORDS, the leftover
          WORDS will be displayed unchanged and if there are more
          display strings than WORDS, the leftover display strings will
          be silently ignored.

     -l
          This option only has an effect if used together with the -d
          option.  If it is given, the display strings are listed one
          per line, not arrayed in columns.

     -o
          This option only has an effect if used together with the -d
          option.  If it is given, the order of the output is determined
          by the match strings; otherwise it is determined by the
          display strings (i.e.  the strings given by the -d option).

     -J NAME
          Gives the name of the group of matches the words should be
          stored in.

     -V NAME
          Like -J but naming an unsorted group.  These are in a
          different name space than groups created with the -J flag.

     -1
          If given together with the -V option, makes only consecutive
          duplicates in the group be removed.  If combined with the -J
          option, this has no visible effect.  Note that groups with and
          without this flag are in different name spaces.

     -2
          If given together with the -J or -V option, makes all
          duplicates be kept.  Again, groups with and without this flag
          are in different name spaces.

     -X EXPLANATION
          The EXPLANATION string will be printed with the list of
          matches, above the group currently selected.

     -x MESSAGE
          Like -X, but the MESSAGE will be printed even if there are no
          matches in the group.

     -q
          The suffix given with -S will be automatically removed if the
          next character typed is a blank or does not insert anything,
          or if the suffix consists of only one character and the next
          character typed is the same character.

     -r REMOVE-CHARS
          This is a more versatile form of the -q option.  The suffix
          given with -S or the slash automatically added after
          completing directories will be automatically removed if the
          next character typed inserts one of the characters given in
          the REMOVE-CHARS.  This string is parsed as a characters class
          and understands the backslash sequences used by the print
          command.  For example, '-r "a-z\t"' removes the suffix if the
          next character typed inserts a lower case character or a TAB,
          and '-r "^0-9"' removes the suffix if the next character typed
          inserts anything but a digit.  One extra backslash sequence is
          understood in this string: '\-' stands for all characters that
          insert nothing.  Thus '-S "=" -q' is the same as '-S "=" -r "=
          \t\n\-"'.

          This option may also be used without the -S option; then any
          automatically added space will be removed when one of the
          characters in the list is typed.

     -R REMOVE-FUNC
          This is another form of the -r option.  When a suffix has been
          inserted and the completion accepted, the function REMOVE-FUNC
          will be called after the next character typed.  It is passed
          the length of the suffix as an argument and can use the
          special parameters available in ordinary (non-completion) zle
          widgets (see *note Zsh Line Editor::) to analyse and modify
          the command line.

     -f
          If this flag is given, all of the matches built from WORDS are
          marked as being the names of files.  They are not required to
          be actual filenames, but if they are, and the option
          LIST_TYPES is set, the characters describing the types of the
          files in the completion lists will be shown.  This also forces
          a slash to be added when the name of a directory is completed.

     -e
          This flag can be used to tell the completion code that the
          matches added are parameter names for a parameter expansion.
          This will make the AUTO_PARAM_SLASH and AUTO_PARAM_KEYS
          options be used for the matches.

     -W FILE-PREFIX
          This string is a pathname that will be prepended to each of
          the matches formed by the given WORDS together with any prefix
          specified by the -p option to form a complete filename for
          testing.  Hence it is only useful if combined with the -f
          flag, as the tests will not otherwise be performed.

     -F ARRAY
          Specifies an array containing patterns.  Words matching one of
          these patterns are ignored, i.e.  not considered to be
          possible matches.

          The ARRAY may be the name of an array parameter or a list of
          literal patterns enclosed in parentheses and quoted, as in '-F
          "(*?.o *?.h)"'.  If the name of an array is given, the
          elements of the array are taken as the patterns.

     -Q
          This flag instructs the completion code not to quote any
          metacharacters in the words when inserting them into the
          command line.

     -M MATCH-SPEC
          This gives local match specifications as described below in
          *note Completion Matching Control::.  This option may be given
          more than once.  In this case all MATCH-SPECs given are
          concatenated with spaces between them to form the
          specification string to use.  Note that they will only be used
          if the -U option is not given.

     -n
          Specifies that the words added are to be used as possible
          matches, but are not to appear in the completion listing.

     -U
          If this flag is given, all words given will be accepted and no
          matching will be done by the completion code.  Normally this
          is used in functions that do the matching themselves.

     -O ARRAY
          If this option is given, the WORDS are _not_ added to the set
          of possible completions.  Instead, matching is done as usual
          and all of the WORDS given as arguments that match the string
          on the command line will be stored in the array parameter
          whose name is given as ARRAY.

     -A ARRAY
          As the -O option, except that instead of those of the WORDS
          which match being stored in ARRAY, the strings generated
          internally by the completion code are stored.  For example,
          with a matching specification of '-M "L:|no="', the string
          'nof' on the command line and the string 'foo' as one of the
          WORDS, this option stores the string 'nofoo' in the array,
          whereas the -O option stores the 'foo' originally given.

     -D ARRAY
          As with -O, the WORDS are not added to the set of possible
          completions.  Instead, the completion code tests whether each
          WORD in turn matches what is on the line.  If the Nth WORD
          does not match, the Nth element of the ARRAY is removed.
          Elements for which the corresponding WORD is matched are
          retained.

     -C
          This option adds a special match which expands to all other
          matches when inserted into the line, even those that are added
          after this option is used.  Together with the -d option it is
          possible to specify a string that should be displayed in the
          list for this special match.  If no string is given, it will
          be shown as a string containing the strings that would be
          inserted for the other matches, truncated to the width of the
          screen.

     -E NUMBER
          This option adds NUMBER empty matches after the WORDS have
          been added.  An empty match takes up space in completion
          listings but will never be inserted in the line and can't be
          selected with menu completion or menu selection.  This makes
          empty matches only useful to format completion lists and to
          make explanatory string be shown in completion lists (since
          empty matches can be given display strings with the -d
          option).  And because all but one empty string would otherwise
          be removed, this option implies the -V and -2 options (even if
          an explicit -J option is given).  This can be important to
          note as it affects the name space into which matches are
          added.

     -
     --
          This flag ends the list of flags and options.  All arguments
          after it will be taken as the words to use as matches even if
          they begin with hyphens.

     Except for the -M flag, if any of these flags is given more than
     once, the first one (and its argument) will be used.

compset -p NUMBER
compset -P [ NUMBER ] PATTERN
compset -s NUMBER
compset -S [ NUMBER ] PATTERN
compset -n BEGIN [ END ]
compset -N BEG-PAT [ END-PAT ]
compset -q
     This command simplifies modification of the special parameters,
     while its return status allows tests on them to be carried out.

     The options are:

     -p NUMBER
          If the contents of the PREFIX parameter is longer than NUMBER
          characters, the first NUMBER characters are removed from it
          and appended to the contents of the IPREFIX parameter.

     -P [ NUMBER ] PATTERN
          If the value of the PREFIX parameter begins with anything that
          matches the PATTERN, the matched portion is removed from
          PREFIX and appended to IPREFIX.

          Without the optional NUMBER, the longest match is taken, but
          if NUMBER is given, anything up to the NUMBERth match is
          moved.  If the NUMBER is negative, the NUMBERth longest match
          is moved.  For example, if PREFIX contains the string 'a=b=c',
          then compset -P '*\=' will move the string 'a=b=' into the
          IPREFIX parameter, but compset -P 1 '*\=' will move only the
          string 'a='.

     -s NUMBER
          As -p, but transfer the last NUMBER characters from the value
          of SUFFIX to the front of the value of ISUFFIX.

     -S [ NUMBER ] PATTERN
          As -P, but match the last portion of SUFFIX and transfer the
          matched portion to the front of the value of ISUFFIX.

     -n BEGIN [ END ]
          If the current word position as specified by the parameter
          CURRENT is greater than or equal to BEGIN, anything up to the
          BEGINth word is removed from the words array and the value of
          the parameter CURRENT is decremented by BEGIN.

          If the optional END is given, the modification is done only if
          the current word position is also less than or equal to END.
          In this case, the words from position END onwards are also
          removed from the words array.

          Both BEGIN and END may be negative to count backwards from the
          last element of the words array.

     -N BEG-PAT [ END-PAT ]
          If one of the elements of the words array before the one at
          the index given by the value of the parameter CURRENT matches
          the pattern BEG-PAT, all elements up to and including the
          matching one are removed from the words array and the value of
          CURRENT is changed to point to the same word in the changed
          array.

          If the optional pattern END-PAT is also given, and there is an
          element in the words array matching this pattern, the
          parameters are modified only if the index of this word is
          higher than the one given by the CURRENT parameter (so that
          the matching word has to be after the cursor).  In this case,
          the words starting with the one matching end-pat are also
          removed from the words array.  If words contains no word
          matching END-PAT, the testing and modification is performed as
          if it were not given.

     -q
          The word currently being completed is split on spaces into
          separate words, respecting the usual shell quoting
          conventions.  The resulting words are stored in the words
          array, and CURRENT, PREFIX, SUFFIX, QIPREFIX, and QISUFFIX are
          modified to reflect the word part that is completed.

     In all the above cases the return status is zero if the test
     succeeded and the parameters were modified and non-zero otherwise.
     This allows one to use this builtin in tests such as:

          if compset -P '*\='; then ...

     This forces anything up to and including the last equal sign to be
     ignored by the completion code.

compcall [ -TD ]
     This allows the use of completions defined with the compctl builtin
     from within completion widgets.  The list of matches will be
     generated as if one of the non-widget completion functions
     (complete-word, etc.)  had been called, except that only compctls
     given for specific commands are used.  To force the code to try
     completions defined with the -T option of compctl and/or the
     default completion (whether defined by compctl -D or the builtin
     default) in the appropriate places, the -T and/or -D flags can be
     passed to compcall.

     The return status can be used to test if a matching compctl
     definition was found.  It is non-zero if a compctl was found and
     zero otherwise.

     Note that this builtin is defined by the zsh/compctl module.


File: zsh.info,  Node: Completion Condition Codes,  Next: Completion Matching Control,  Prev: Completion Builtin Commands,  Up: Completion Widgets

19.4 Completion Condition Codes
===============================

The following additional condition codes for use within the [[ ...  ]]
construct are available in completion widgets.  These work on the
special parameters.  All of these tests can also be performed by the
compset builtin, but in the case of the condition codes the contents of
the special parameters are not modified.

-prefix [ NUMBER ] PATTERN
     true if the test for the -P option of compset would succeed.

-suffix [ NUMBER ] PATTERN
     true if the test for the -S option of compset would succeed.

-after BEG-PAT
     true if the test of the -N option with only the BEG-PAT given would
     succeed.

-between BEG-PAT END-PAT
     true if the test for the -N option with both patterns would
     succeed.


File: zsh.info,  Node: Completion Matching Control,  Next: Completion Widget Example,  Prev: Completion Condition Codes,  Up: Completion Widgets

19.5 Completion Matching Control
================================

It is possible by use of the -M option of the compadd builtin command to
specify how the characters in the string to be completed (referred to
here as the command line) map onto the characters in the list of matches
produced by the completion code (referred to here as the trial
completions).  Note that this is not used if the command line contains a
glob pattern and the GLOB_COMPLETE option is set or the pattern_match of
the compstate special association is set to a non-empty string.

The MATCH-SPEC given as the argument to the -M option (see *note
Completion Builtin Commands::) consists of one or more matching
descriptions separated by whitespace.  Each description consists of a
letter followed by a colon and then the patterns describing which
character sequences on the line match which character sequences in the
trial completion.  Any sequence of characters not handled in this
fashion must match exactly, as usual.

The forms of MATCH-SPEC understood are as follows.  In each case, the
form with an upper case initial character retains the string already
typed on the command line as the final result of completion, while with
a lower case initial character the string on the command line is changed
into the corresponding part of the trial completion.

m:LPAT=TPAT
M:LPAT=TPAT
     Here, LPAT is a pattern that matches on the command line,
     corresponding to TPAT which matches in the trial completion.

l:LANCHOR|LPAT=TPAT
L:LANCHOR|LPAT=TPAT
l:LANCHOR||RANCHOR=TPAT
L:LANCHOR||RANCHOR=TPAT
b:LPAT=TPAT
B:LPAT=TPAT
     These letters are for patterns that are anchored by another pattern
     on the left side.  Matching for LPAT and TPAT is as for m and M,
     but the pattern LPAT matched on the command line must be preceded
     by the pattern LANCHOR.  The LANCHOR can be blank to anchor the
     match to the start of the command line string; otherwise the anchor
     can occur anywhere, but must match in both the command line and
     trial completion strings.

     If no LPAT is given but a RANCHOR is, this matches the gap between
     substrings matched by LANCHOR and RANCHOR.  Unlike LANCHOR, the
     RANCHOR only needs to match the trial completion string.

     The b and B forms are similar to l and L with an empty anchor, but
     need to match only the beginning of the word on the command line or
     trial completion, respectively.

r:LPAT|RANCHOR=TPAT
R:LPAT|RANCHOR=TPAT
r:LANCHOR||RANCHOR=TPAT
R:LANCHOR||RANCHOR=TPAT
e:LPAT=TPAT
E:LPAT=TPAT
     As l, L, b and B, with the difference that the command line and
     trial completion patterns are anchored on the right side.  Here an
     empty RANCHOR and the e and E forms force the match to the end of
     the command line or trial completion string.

x:
     This form is used to mark the end of matching specifications:
     subsequent specifications are ignored.  In a single standalone list
     of specifications this has no use but where matching specifications
     are accumulated, such as from nested function calls, it can allow
     one function to override another.

Each LPAT, TPAT or ANCHOR is either an empty string or consists of a
sequence of literal characters (which may be quoted with a backslash),
question marks, character classes, and correspondence classes; ordinary
shell patterns are not used.  Literal characters match only themselves,
question marks match any character, and character classes are formed as
for globbing and match any character in the given set.

Correspondence classes are defined like character classes, but with two
differences: they are delimited by a pair of braces, and negated classes
are not allowed, so the characters ! and ^ have no special meaning
directly after the opening brace.  They indicate that a range of
characters on the line match a range of characters in the trial
completion, but (unlike ordinary character classes) paired according to
the corresponding position in the sequence.  For example, to make any
ASCII lower case letter on the line match the corresponding upper case
letter in the trial completion, you can use 'm:{a-z}={A-Z}' (however,
see below for the recommended form for this).  More than one pair of
classes can occur, in which case the first class before the =
corresponds to the first after it, and so on.  If one side has more such
classes than the other side, the superfluous classes behave like normal
character classes.  In anchor patterns correspondence classes also
behave like normal character classes.

The standard '[:NAME:]' forms described for standard shell patterns (see
*note Filename Generation::) may appear in correspondence classes as
well as normal character classes.  The only special behaviour in
correspondence classes is if the form on the left and the form on the
right are each one of [:upper:], [:lower:].  In these cases the
character in the word and the character on the line must be the same up
to a difference in case.  Hence to make any lower case character on the
line match the corresponding upper case character in the trial
completion you can use 'm:{[:lower:]}={[:upper:]}'.  Although the
matching system does not yet handle multibyte characters, this is likely
to be a future extension, at which point this syntax will handle
arbitrary alphabets; hence this form, rather than the use of explicit
ranges, is the recommended form.  In other cases '[:NAME:]' forms are
allowed.  If the two forms on the left and right are the same, the
characters must match exactly.  In remaining cases, the corresponding
tests are applied to both characters, but they are not otherwise
constrained; any matching character in one set goes with any matching
character in the other set: this is equivalent to the behaviour of
ordinary character classes.

The pattern TPAT may also be one or two stars, '*' or '**'.  This means
that the pattern on the command line can match any number of characters
in the trial completion.  In this case the pattern must be anchored (on
either side); in the case of a single star, the ANCHOR then determines
how much of the trial completion is to be included -- only the
characters up to the next appearance of the anchor will be matched.
With two stars, substrings matched by the anchor can be matched, too.

Examples:

The keys of the options association defined by the parameter module are
the option names in all-lower-case form, without underscores, and
without the optional no at the beginning even though the builtins setopt
and unsetopt understand option names with upper case letters,
underscores, and the optional no.  The following alters the matching
rules so that the prefix no and any underscore are ignored when trying
to match the trial completions generated and upper case letters on the
line match the corresponding lower case letters in the words:

     compadd -M 'L:|[nN][oO]= M:_= M:{[:upper:]}={[:lower:]}' - \
       ${(k)options}

The first part says that the pattern '[nN][oO]' at the beginning (the
empty anchor before the pipe symbol) of the string on the line matches
the empty string in the list of words generated by completion, so it
will be ignored if present.  The second part does the same for an
underscore anywhere in the command line string, and the third part uses
correspondence classes so that any upper case letter on the line matches
the corresponding lower case letter in the word.  The use of the upper
case forms of the specification characters (L and M) guarantees that
what has already been typed on the command line (in particular the
prefix no) will not be deleted.

Note that the use of L in the first part means that it matches only when
at the beginning of both the command line string and the trial
completion.  I.e., the string '_NO_f' would not be completed to
'_NO_foo', nor would 'NONO_f' be completed to 'NONO_foo' because of the
leading underscore or the second 'NO' on the line which makes the
pattern fail even though they are otherwise ignored.  To fix this, one
would use 'B:[nN][oO]=' instead of the first part.  As described above,
this matches at the beginning of the trial completion, independent of
other characters or substrings at the beginning of the command line word
which are ignored by the same or other MATCH-SPECs.

The second example makes completion case insensitive.  This is just the
same as in the option example, except here we wish to retain the
characters in the list of completions:

     compadd -M 'm:{[:lower:]}={[:upper:]}' ...

This makes lower case letters match their upper case counterparts.  To
make upper case letters match the lower case forms as well:

     compadd -M 'm:{[:lower:][:upper:]}={[:upper:][:lower:]}' ...

A nice example for the use of * patterns is partial word completion.
Sometimes you would like to make strings like 'c.s.u' complete to
strings like 'comp.source.unix', i.e.  the word on the command line
consists of multiple parts, separated by a dot in this example, where
each part should be completed separately -- note, however, that the case
where each part of the word, i.e.  'comp', 'source' and 'unix' in this
example, is to be completed from separate sets of matches is a different
problem to be solved by the implementation of the completion widget.
The example can be handled by:

     compadd -M 'r:|.=* r:|=*' \
       - comp.sources.unix comp.sources.misc ...

The first specification says that LPAT is the empty string, while ANCHOR
is a dot; TPAT is *, so this can match anything except for the '.' from
the anchor in the trial completion word.  So in 'c.s.u', the matcher
sees 'c', followed by the empty string, followed by the anchor '.', and
likewise for the second dot, and replaces the empty strings before the
anchors, giving 'c[omp].s[ources].u[nix]', where the last part of the
completion is just as normal.

With the pattern shown above, the string 'c.u' could not be completed to
'comp.sources.unix' because the single star means that no dot (matched
by the anchor) can be skipped.  By using two stars as in 'r:|.=**',
however, 'c.u' could be completed to 'comp.sources.unix'.  This also
shows that in some cases, especially if the anchor is a real pattern,
like a character class, the form with two stars may result in more
matches than one would like.

The second specification is needed to make this work when the cursor is
in the middle of the string on the command line and the option
COMPLETE_IN_WORD is set.  In this case the completion code would
normally try to match trial completions that end with the string as
typed so far, i.e.  it will only insert new characters at the cursor
position rather than at the end.  However in our example we would like
the code to recognise matches which contain extra characters after the
string on the line (the 'nix' in the example).  Hence we say that the
empty string at the end of the string on the line matches any characters
at the end of the trial completion.

More generally, the specification

     compadd -M 'r:|[.,_-]=* r:|=*' ...

allows one to complete words with abbreviations before any of the
characters in the square brackets.  For example, to complete
veryverylongfile.c rather than veryverylongheader.h with the above in
effect, you can just type very.c before attempting completion.

The specifications with both a left and a right anchor are useful to
complete partial words whose parts are not separated by some special
character.  For example, in some places strings have to be completed
that are formed 'LikeThis' (i.e.  the separate parts are determined by a
leading upper case letter) or maybe one has to complete strings with
trailing numbers.  Here one could use the simple form with only one
anchor as in:

     compadd -M 'r:|[[:upper:]0-9]=* r:|=*' LikeTHIS FooHoo 5foo123 5bar234

But with this, the string 'H' would neither complete to 'FooHoo' nor to
'LikeTHIS' because in each case there is an upper case letter before the
'H' and that is matched by the anchor.  Likewise, a '2' would not be
completed.  In both cases this could be changed by using
'r:|[[:upper:]0-9]=**', but then 'H' completes to both 'LikeTHIS' and
'FooHoo' and a '2' matches the other strings because characters can be
inserted before every upper case letter and digit.  To avoid this one
would use:

     compadd -M 'r:[^[:upper:]0-9]||[[:upper:]0-9]=** r:|=*' \
         LikeTHIS FooHoo foo123 bar234

By using these two anchors, a 'H' matches only upper case 'H's that are
immediately preceded by something matching the left anchor
'[^[:upper:]0-9]'.  The effect is, of course, that 'H' matches only the
string 'FooHoo', a '2' matches only 'bar234' and so on.

When using the completion system (see *note Completion System::), users
can define match specifications that are to be used for specific
contexts by using the matcher and matcher-list styles.  The values for
the latter will be used everywhere.


File: zsh.info,  Node: Completion Widget Example,  Prev: Completion Matching Control,  Up: Completion Widgets

19.6 Completion Widget Example
==============================

The first step is to define the widget:

     zle -C complete complete-word complete-files

Then the widget can be bound to a key using the bindkey builtin command:

     bindkey '^X\t' complete

After that the shell function complete-files will be invoked after
typing control-X and TAB. The function should then generate the matches,
e.g.:

     complete-files () { compadd - * }

This function will complete files in the current directory matching the
current word.


File: zsh.info,  Node: Completion System,  Next: Completion Using compctl,  Prev: Completion Widgets,  Up: Top

20 Completion System
********************

20.1 Description
================

This describes the shell code for the 'new' completion system, referred
to as compsys.  It is written in shell functions based on the features
described in the previous chapter, *note Completion Widgets::.

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 in *note
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 *note The
zsh/zutil Module::.

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
in *note Completion System Configuration::.

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

More generally, the shell functions contained in the completion system
are of two types:

   * 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.

* Menu:

* Initialization::
* Completion System Configuration::
* Control Functions::
* Bindable Commands::
* Completion Functions::
* Completion Directories::
* Completion System Variables::


File: zsh.info,  Node: Initialization,  Next: Completion System Configuration,  Up: Completion System

20.2 Initialization
===================

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

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

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

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

20.2.1 Use of compinit
----------------------

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

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

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

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

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

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

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

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

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

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

20.2.2 Autoloaded files
-----------------------

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

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

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

The tags are:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

-command-
     A word in command position

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

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

-equal-
     A word beginning with an equals sign

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

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

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

-redirect-
     The word after a redirection operator.

-subscript-
     The contents of a parameter subscript.

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

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

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

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

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

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

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

As an example:

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

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

Also:

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

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

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

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

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

20.2.3 Functions
----------------

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

compdef [ -ane ] FUNCTION NAME ... [ -{p|P} PATTERN ... [ -N NAME ...]]
compdef -d NAME ...
compdef -k [ -an ] FUNCTION STYLE KEY-SEQUENCE [ KEY-SEQUENCE ... ]
compdef -K [ -an ] FUNCTION NAME STYLE KEY-SEQ [ NAME STYLE SEQ ... ]
     The first form defines the FUNCTION to call for completion in the
     given contexts as described for the #compdef tag above.

     Alternatively, all the arguments may have the form 'CMD=SERVICE'.
     Here SERVICE should already have been defined by 'CMD1=SERVICE'
     lines in #compdef files, as described above.  The argument for CMD
     will be completed in the same way as SERVICE.

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

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

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

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

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

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

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

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

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

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

     compdef _pids foo

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

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


File: zsh.info,  Node: Completion System Configuration,  Next: Control Functions,  Prev: Initialization,  Up: Completion System

20.3 Completion System Configuration
====================================

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

20.3.1 Overview
---------------

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

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

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

The next few paragraphs explain how a context is composed within the
completion function suite.  Following that is discussion of how _styles_
are defined.  Styles determine such things as how the matches are
generated, similarly to shell options but with much more control.  They
are defined with the zstyle builtin command (*note The zsh/zutil
Module::).

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

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

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

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

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

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

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

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

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

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

     dvips -o ...

and the completion function will generate filenames.

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

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

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

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

     zstyle ':completion:*' verbose yes

in a startup file (probably .zshrc).  This gives the verbose style the
value yes in every context inside the completion system, unless that
context has a more specific definition.  It is best to avoid giving the
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 numbers and PIDs.  To turn the style off for this use only:

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

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

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

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

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

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

Note that the order in which styles are _defined_ does not matter; the
style mechanism uses the most specific possible match for a particular
style to determine the set of values.  More precisely, strings are
preferred over patterns (for example, ':completion::complete:::foo' is
more specific than ':completion::complete:::*'), and longer patterns are
preferred over shorter patterns.

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

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

20.3.2 Standard Tags
--------------------

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

accounts
     used to look up the users-hosts style

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

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

arguments
     for arguments to a command

arrays
     for names of array parameters

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

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

builtins
     for names of builtin commands

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

colormapids
     for X colormap ids

colors
     for color names

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

contexts
     for contexts in arguments to the zstyle builtin command

corrections
     used by the _approximate and _correct completers for possible
     corrections

cursors
     for cursor names used by X programs

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

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

devices
     for names of device special files

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

directory-stack
     for entries in the directory stack

displays
     for X display names

domains
     for network domains

email-PLUGIN
     for email addresses from the '_email-PLUGIN' backend of
     _email_addresses

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

extensions
     for X server extensions

file-descriptors
     for numbers of open file descriptors

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

fonts
     for X font names

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

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

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

groups
     for names of user groups

history-words
     for words from the history

hosts
     for hostnames

indexes
     for array indexes

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

interfaces
     for network interfaces

keymaps
     for names of zsh keymaps

keysyms
     for names of X keysyms

libraries
     for names of system libraries

limits
     for system limits

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

manuals
     for names of manual pages

mailboxes
     for e-mail folders

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

messages
     used to look up the format style for messages

modifiers
     for names of X modifiers

modules
     for modules (e.g.  zsh modules)

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

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

names
     for all kinds of names

newsgroups
     for USENET groups

nicknames
     for nicknames of NIS maps

options
     for command options

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

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

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

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

parameters
     for names of parameters

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

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

pods
     for perl pods (documentation files)

ports
     for communication ports

prefixes
     for prefixes (like those of a URL)

printers
     for print queue names

processes
     for process identifiers

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

sequences
     for sequences (e.g.  mh sequences)

sessions
     for sessions in the zftp function suite

signals
     for signal names

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

styles
     for styles used by the zstyle builtin command

suffixes
     for filename extensions

tags
     for tags (e.g.  rpm tags)

targets
     for makefile targets

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

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

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

users
     for usernames

values
     for one of a set of values in certain lists

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

visuals
     for X visuals

warnings
     used to look up the format style for warnings

widgets
     for zsh widget names

windows
     for IDs of X windows

zsh-options
     for shell options

20.3.3 Standard Styles
----------------------

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

completer
     The strings given as the value of this style provide the names of
     the completer functions to use.  The available completer functions
     are described in *note Control Functions::.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     This can be useful on systems that support special file systems
     whose top-level pathnames can not be listed or generated with glob
     patterns.  It can also be used for directories for which one does
     not have read permission.

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

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

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

          zmodload -i zsh/stat
          disable stat

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

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

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

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

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

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

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

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

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

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

     The TAG may also be followed by an optional second colon and a
     description, which will be used for the '%d' in the value of the
     format style (if that is set) instead of the default description
     supplied by the completion function.  If the description given here
     contains itself a '%d', that is replaced with the description
     supplied by the completion function.

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

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

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

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

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

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

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

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

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

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

format
     If this is set for the descriptions tag, its value is used as a
     string to display above matches in completion lists.  The sequence
     '%d' in this string will be replaced with a short description of
     what these matches are.  This string may also contain the following
     sequences to specify output attributes (see *note Prompt
     Expansion::): '%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
     sequence '%G' 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 descriptions tag.  Hence different
     format strings can be defined for different types of match.

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

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

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

     It is possible to use printf-style field width specifiers with '%d'
     and similar escape sequences.  This is handled by the zformat
     builtin command from the zsh/zutil module, see *note The zsh/zutil
     Module::.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

keep-prefix
     This style is used by the _expand completer.  If it is 'true', the
     completer will try to keep a prefix containing a tilde or parameter
     expansion.  Hence, for 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.

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

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

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

list-colors
     If the zsh/complist module is loaded, this style can be used to set
     color specifications.  This mechanism replaces the use of the
     ZLS_COLORS and ZLS_COLOURS parameters described in *note The
     zsh/complist Module::, but the syntax is the same.

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

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

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

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

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

list-dirs-first
     This is used by file completion.  If set, directories to be
     completed are listed separately from and before completion for
     other files, regardless of tag ordering.  In addition, the tag
     other-files is used in place of all-files for the remaining files,
     to indicate that no directories are presented with that tag.

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

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

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

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

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

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

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

list-separator
     The value of this style is used in completion listing to separate
     the string to complete from a description when possible (e.g.  when
     completing options).  It 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/public/toast/stuff, while completion after
     'http://toast/~yousir/' will look for files in the directory
     ~yousir/public_html.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     Similarly, with any of the 'false' values (as in 'no=10'), menu
     completion will _not_ be used if there are NUM or more matches.

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

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

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

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

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

     To turn on menu completion or menu selection when 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
     *note The zsh/complist Module:: for a description of interactive
     mode.  Including the string 'search' does the same for incremental
     search mode.  To select backward incremental search, include the
     string 'search-backward'.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     The default value for this style is 'false'.

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

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

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

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

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

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

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

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

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

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

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

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

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

     For example,

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

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

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

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

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

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

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

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

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

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

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

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

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

sort
     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.

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

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

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

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

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

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

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

     The default for this style is 'false'.

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

     The default is 'true'.

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

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

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

     For example:

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

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

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

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

     ! TAGS...
          A string starting with an exclamation mark specifies names of
          tags that are _not_ to be used.  The effect is the same as if
          all other possible tags for the context had been listed.

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

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

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

     In any of the forms above the tag may be a pattern or several
     patterns in the form '{PAT1,PAT2...}'.  In this case all matching
     tags will be used except for any given explicitly in the same
     string.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     For example,

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


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

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

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

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

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

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

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

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

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

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

users-hosts-ports
     Like users-hosts but used for commands like telnet and containing
     strings of the form 'USER@HOST:PORT'.

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

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


File: zsh.info,  Node: Control Functions,  Next: Bindable Commands,  Prev: Completion System Configuration,  Up: Completion System

20.4 Control Functions
======================

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

     zstyle ':completion:*' completer _complete _correct

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

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

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

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

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

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

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

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

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

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

          zstyle ':completion:*' completer _complete _approximate

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

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

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

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

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

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

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

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

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

     See _description for a description of TAG and DESCR.

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

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

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

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

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

     For example, with:

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

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

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

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

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

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

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

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

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

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

     This function is also a bindable command, see *note Bindable
     Commands::.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     For example, consider this global completer style:

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

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

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

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

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

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

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

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

     $HASH

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

     _FUNC

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


File: zsh.info,  Node: Bindable Commands,  Next: Completion Functions,  Prev: Control Functions,  Up: Completion System

20.5 Bindable Commands
======================

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     For example, after executing the following:

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

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

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


File: zsh.info,  Node: Completion Functions,  Next: Completion System Variables,  Prev: Bindable Commands,  Up: Completion System

20.6 Utility Functions
======================

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

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

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

     For example:

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

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

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

     The tags to use and the action to perform if a tag is requested are
     described using the SPECs which are of the form:
     'TAG:DESCR:ACTION'.  The TAGs are offered using _tags and if the
     tag is requested, the ACTION is executed with the given description
     DESCR.  The ACTIONs are those accepted by the _arguments function
     (described below), excluding the '->STATE' and '=...' forms.

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

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

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

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

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

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

_arguments [ -nswWCRS ] [ -A PAT ] [ -O NAME ] [ -M MATCHSPEC ]
           [ : ] SPEC ...
_arguments [ OPT ... ] -- [ -i PATS ] [ -s PAIR ] [ HELPSPEC ... ]
     This function can be used to give a complete specification for
     completion for a command whose arguments follow standard UNIX
     option and argument conventions.

     _Options overview_

     Options to _arguments itself must be in separate words, i.e.  -s
     -w, not -sw.  The options are followed by SPECs that describe
     options and arguments of the analyzed command.  SPECs that describe
     option flags must precede SPECs that describe non-option
     ("positional" or "normal") arguments of the analyzed line.  To
     avoid ambiguity, all options to _arguments itself may be separated
     from the SPEC forms by a single colon.

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

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

     The options of _arguments have the following meanings:

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

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

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

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

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

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

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

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

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

               foobar -x -- -y

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

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

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

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

     _SPECs: overview_

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

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

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

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

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

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

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

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

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

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

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

          -OPTNAME-
               The first argument of the option must come directly after
               the option name _in the same word_.  For example,
               '-foo-:...' specifies that the completed option and
               argument will look like '-fooARG'.

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

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

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

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

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

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

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

          Each OPTARG following an OPTSPEC must take one of the
          following forms:

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

               This group may be repeated for options which take
               multiple arguments.  In other words,
               :MESSAGE1:ACTION1:MESSAGE2:ACTION2 specifies that the
               option takes two arguments.

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

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

     Any literal colon in an OPTNAME, MESSAGE, or ACTION must be
     preceded by a backslash, '\:'.

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

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

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

     _SPECs: actions_

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

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

     The forms for ACTION are as follows.

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

     (ITEM1 ITEM2 ...)
          One of a list of possible matches, for example:

               :foo:(foo bar baz)

     ((ITEM1\:DESC1 ...))
          Similar to the above, but with descriptions for each possible
          match.  Note the backslash before the colon.  For example,

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

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

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

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

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

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

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

               local context state state_descr line
               typeset -A opt_args

          to prevent _arguments from altering the global environment.

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

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

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

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

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

     During the performance of the action the array 'line' will be set
     to the normal arguments from the command line, i.e.  the words from
     the command line after the command name excluding all options and
     their arguments.  Options are stored in the associative array
     'opt_args' with option names as keys and their arguments as the
     values.  For options that have more than one argument these are
     given as one string, separated by colons.  All colons and
     backslashes in the original arguments are preceded with
     backslashes.

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

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

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

          local curcontext="$curcontext"

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

     _Specifying multiple sets of options_

     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 considered.  However, after '-a' both sets
     will still be considered valid.

     If an option in a set appears on the command line, it is stored in
     the associative array 'opt_args' with 'SET-OPTION' as a key.  In
     the example above, a key 'set1--c' is used if the option '-c' is on
     the command line.

     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 specifications 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)' \
              {-d,--decompress}'[decompress]'

     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
     definitions.

     _Deriving SPEC forms from the help output_

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

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

     For example:

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

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

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

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

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

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

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

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

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

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

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

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

     _Miscellaneous notes_

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

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

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

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

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

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

     The last two descriptions say what should be completed as
     arguments.  The first describes the first argument as a 'POSTSCRIPT
     FILE' and makes files ending in 'ps' or 'eps' be completed.  The
     last description gives all other arguments the description 'PAGE
     NUMBERS' but does not offer completions.

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

     Example:

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

_call_function RETURN NAME [ ARG ... ]
     If a function NAME exists, it is called with the arguments ARGs.
     The RETURN 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 [ -p ] TAG STRING ...
     This function provides a mechanism for the user to override the use
     of an external command.  It looks up the command style with the
     supplied TAG.  If the style is set, its value is used as the
     command to execute.  The STRINGs from the call to _call_program, or
     from the style if set, are concatenated with spaces between them
     and the resulting string is evaluated.  The return status is the
     return status of the command called.

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

_combination [ -s PATTERN ] TAG STYLE SPEC ... FIELD OPTS ...
     This function is used to complete combinations of values, for
     example pairs of hostnames and usernames.  The STYLE argument gives
     the style which defines the pairs; it is looked up in a context
     with the TAG specified.

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

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

     The matches generated will be taken from the value of the style.
     These should contain the possible values for the combinations in
     the appropriate order (users, hosts, ports in the example above).
     The different 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 example '-s "[:@]"' in the case of the
     users-hosts style.  Each 'FIELD=PATTERN' specification restricts
     the completions which apply to elements of the style with
     appropriately matching fields.

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

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

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

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

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

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

_describe [-12JVx] [ -oO | -t TAG ] DESCR NAME1 [ NAME2 ] [ OPT ... ]
          [ -- NAME1 [ NAME2 ] [ OPT ... ] ... ]
     This function associates completions with descriptions.  Multiple
     groups separated by -- can be supplied, potentially with different
     completion options OPTs.

     The DESCR is taken as a string to display above the matches if the
     format style for the descriptions tag is set.  This is followed by
     one or two names of arrays followed by options to pass to compadd.
     The array NAME1 contains the possible completions with their
     descriptions in the form 'COMPLETION:DESCRIPTION'.  Any literal
     colons in COMPLETION must be quoted with a backslash.  If a NAME2
     is given, it should have the same number of elements as NAME1; in
     this case the corresponding elements are added as possible
     completions instead of the COMPLETION strings from NAME1.  The
     completion list will retain the descriptions from NAME1.  Finally,
     a set of completion options can appear.

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

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

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

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

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

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

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

     The styles tested are: format, hidden, matcher, 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 removing the white space, the DESCR is the empty string, the
     format style will not be used and the options put into the NAME
     array will not contain an explanation string to be displayed above
     the matches.

     If _description is called with more than three arguments, the
     additional SPECs should be of the form 'CHAR:STR'.  These supply
     escape sequence replacements for the format style: every appearance
     of '%CHAR' will be replaced by STRING.

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

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

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

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

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

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

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

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

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

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

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

     -c
          Complete bare localhost@domain.tld addresses, without a name
          part or a comment.  Without this option, RFC822 'FIRSTNAME
          LASTNAME <ADDRESS>' strings are completed.

     -n PLUGIN
          Complete aliases from PLUGIN.

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

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

     _Writing plugins_

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

_files
     The function _files 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.

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

          compdef _gnu_generic foo bar

     after the call to compinit.

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

_guard [ OPTIONS ] PATTERN DESCR
     This function displays DESCR if PATTERN matches the string to be
     completed.  It is intended to be used in the ACTION for the
     specifications passed to _arguments and similar functions.

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

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

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

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

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

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

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

     If the -r option is given, no style is used; the DESCR is taken
     literally as the string to display.  This is most useful when the
     DESCR comes from a pre-processed argument list which already
     contains an expanded description.

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

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

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

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

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

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

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

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

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

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

_normal
     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-command 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.

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

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

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

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

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

     All other arguments are passed to the compadd builtin.

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

     The options accepted by both _path_files and _files are:

     -f
          Complete all filenames.  This is the default.

     -/
          Specifies that only directories should be completed.

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

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

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

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

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

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

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

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

     If the '-r NAME' is given, the LABEL picked is stored in the
     parameter named NAME.

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

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

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

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

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

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

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

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

     /PATTERN/+ [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to '/PATTERN/ ...'  but the left part of the
          command line string (i.e.  the part already matched by
          previous patterns) is also considered part of the completion
          target.

     /PATTERN/- [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to '/PATTERN/ ...'  but the ACTIONs of the
          current and previously matched patterns are ignored even if
          the following 'PATTERN' matches the empty string.

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

     SPEC #
          This allows any number of repetitions of SPEC.

     SPEC SPEC
          The two SPECs are to be matched one after the other as
          described above.

     SPEC | SPEC
          Either of the two SPECs can be matched.

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

     Examples:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     For example:

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

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

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

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

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

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

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

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

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

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

     See _store_cache below for more details.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

_values [ -O NAME ] [ -s SEP ] [ -S SEP ] [ -wC ] DESC SPEC ...
     This is used to complete arbitrary keywords (values) and their
     arguments, or lists of such combinations.

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

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

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

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

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

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

     Example:

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

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

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

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

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

          local context state state_descr line
          typeset -A val_args

     when using an action of the form '->STRING'.  With this function
     the context parameter will be set to the name of the value whose
     argument is to be completed.  Note that for _values, the state and
     state_descr are scalars rather than arrays.  Only a single matching
     state is returned.

     Note also that _values normally adds the character used as the
     separator between values as an auto-removable suffix (similar to a
     '/' after a directory).  However, this is not possible for a
     '->STRING' action as the matches for the argument are generated by
     the calling function.  To get the usual behaviour, the calling
     function can add the separator X as a suffix by passing the options
     '-qS X' either directly or indirectly to compadd.

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

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

     The arguments to _wanted are the same as those to _requested, i.e.
     arguments to be passed to _description.  However, in this case the
     COMMAND is not optional; all the processing of tags, including the
     loop over both tags and tag labels and the generation of matches,
     is carried out automatically by _wanted.

     Hence to offer only one tag and immediately add the corresponding
     matches with the given description:

          local expl
          _wanted tag expl 'description' \
              compadd matches...

     Note that, as for _requested, the COMMAND must be able to accept
     options to be passed down to compadd.

     Like _tags this function supports the -C option to give a different
     name for the argument context field.  The -x option has the same
     meaning as for _description.

_widgets [ -g PATTERN ]
     This function completes names of zle widgets (see *note Zle
     Widgets::).  The PATTERN, if present, is matched against values of
     the $widgets special parameter, documented in *note The
     zsh/zleparameter Module::.


File: zsh.info,  Node: Completion System Variables,  Next: Completion Directories,  Prev: Completion Functions,  Up: Completion System

20.7 Completion System Variables
================================

There are some standard variables, initialised by the _main_complete
function and then used from other functions.

The standard variables are:

_comp_caller_options
     The completion system uses setopt to set a number of options.  This
     allows functions to be written without concern for compatibility
     with every possible combination of user options.  However,
     sometimes completion needs to know what the user's option
     preferences are.  These are saved in the _comp_caller_options
     associative array.  Option names, spelled in lowercase without
     underscores, are mapped to one or other of the strings 'on' and
     'off'.

_comp_priv_prefix
     Completion functions such as _sudo can set the _comp_priv_prefix
     array to a command prefix that may then be used by _call_program to
     match the privileges when calling programs to generate matches.

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


File: zsh.info,  Node: Completion Directories,  Prev: Completion System Variables,  Up: Completion System

20.8 Completion Directories
===========================

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

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

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

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

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


File: zsh.info,  Node: Completion Using compctl,  Next: Zsh Modules,  Prev: Completion System,  Up: Top

21 Completion Using compctl
***************************

21.1 Types of completion
========================

This version of zsh has two ways of performing completion of words on
the command line.  New users of the shell may prefer to use the newer
and more powerful system based on shell functions; this is described in
*note Completion System::, and the basic shell mechanisms which support
it are described in *note Completion Widgets::.  This chapter describes
the older compctl command.

21.2 Description
================

compctl [ -CDT ] OPTIONS [ COMMAND ... ]
compctl [ -CDT ] OPTIONS [ -x PATTERN OPTIONS - ... -- ]
        [ + OPTIONS [ -x ... -- ] ... [+] ] [ COMMAND ... ]
compctl -M MATCH-SPECS ...
compctl -L [ -CDTM ] [ COMMAND ... ]
compctl + COMMAND ...

Control the editor's completion behavior according to the supplied set
of OPTIONS.  Various editing commands, notably expand-or-complete-word,
usually bound to tab, will attempt to complete a word typed by the user,
while others, notably delete-char-or-list, usually bound to ^D in EMACS
editing mode, list the possibilities; compctl controls what those
possibilities are.  They may for example be filenames (the most common
case, and hence the default), shell variables, or words from a
user-specified list.
* Menu:

* Command Flags::
* Option Flags::
* Alternative Completion::
* Extended Completion::
* Example::


File: zsh.info,  Node: Command Flags,  Next: Option Flags,  Up: Completion Using compctl

21.3 Command Flags
==================

Completion of the arguments of a command may be different for each
command or may use the default.  The behavior when completing the
command word itself may also be separately specified.  These correspond
to the following flags and arguments, all of which (except for -L) may
be combined with any combination of the OPTIONS described subsequently
in *note Option Flags:::

COMMAND ...
     controls completion for the named commands, which must be listed
     last on the command line.  If completion is attempted for a command
     with a pathname containing slashes and no completion definition is
     found, the search is retried with the last pathname component.  If
     the command starts with a =, completion is tried with the pathname
     of the command.

     Any of the COMMAND strings may be patterns of the form normally
     used for filename generation.  These should be quoted to protect
     them from immediate expansion; for example the command string
     'foo*' arranges for completion of the words of any command
     beginning with foo.  When completion is attempted, all pattern
     completions are tried in the reverse order of their definition
     until one matches.  By default, completion then proceeds as normal,
     i.e.  the shell will try to generate more matches for the specific
     command on the command line; this can be overridden by including
     -tn in the flags for the pattern completion.

     Note that aliases are expanded before the command name is
     determined unless the COMPLETE_ALIASES option is set.  Commands may
     not be combined with the -C, -D or -T flags.

-C
     controls completion when the command word itself is being
     completed.  If no compctl -C command has been issued, the names of
     any executable command (whether in the path or specific to the
     shell, such as aliases or functions) are completed.

-D
     controls default completion behavior for the arguments of commands
     not assigned any special behavior.  If no compctl -D command has
     been issued, filenames are completed.

-T
     supplies completion flags to be used before any other processing is
     done, even before processing for compctls defined for specific
     commands.  This is especially useful when combined with extended
     completion (the -x flag, see *note Extended Completion:: below).
     Using this flag you can define default behavior which will apply to
     all commands without exception, or you can alter the standard
     behavior for all commands.  For example, if your access to the user
     database is too slow and/or it contains too many users (so that
     completion after '~' is too slow to be usable), you can use

          compctl -T -x 's[~] C[0,[^/]#]' -k friends -S/ -tn

     to complete the strings in the array friends after a '~'.  The
     C[...] argument is necessary so that this form of ~-completion is
     not tried after the directory name is finished.

-L
     lists the existing completion behavior in a manner suitable for
     putting into a start-up script; the existing behavior is not
     changed.  Any combination of the above forms, or the -M flag (which
     must follow the -L flag), may be specified, otherwise all defined
     completions are listed.  Any other flags supplied are ignored.

_no argument_
     If no argument is given, compctl lists all defined completions in
     an abbreviated form; with a list of OPTIONS, all completions with
     those flags set (not counting extended completion) are listed.

If the + flag is alone and followed immediately by the COMMAND list, the
completion behavior for all the commands in the list is reset to the
default.  In other words, completion will subsequently use the options
specified by the -D flag.

The form with -M as the first and only option defines global matching
specifications (see *note Completion Matching Control::).  The match
specifications given will be used for every completion attempt (only
when using compctl, not with the new completion system) and are tried in
the order in which they are defined until one generates at least one
match.  E.g.:

     compctl -M '' 'm:{a-zA-Z}={A-Za-z}'

This will first try completion without any global match specifications
(the empty string) and, if that generates no matches, will try case
insensitive completion.


File: zsh.info,  Node: Option Flags,  Next: Alternative Completion,  Prev: Command Flags,  Up: Completion Using compctl

21.4 Option Flags
=================

[ -fcFBdeaRGovNAIOPZEnbjrzu/12 ]
[ -k ARRAY ] [ -g GLOBSTRING ] [ -s SUBSTSTRING ]
[ -K FUNCTION ]
[ -Q ] [ -P PREFIX ] [ -S SUFFIX ]
[ -W FILE-PREFIX ] [ -H NUM PATTERN ]
[ -q ] [ -X EXPLANATION ] [ -Y EXPLANATION ]
[ -y FUNC-OR-VAR ] [ -l CMD ] [ -h CMD ] [ -U ]
[ -t CONTINUE ] [ -J NAME ] [ -V NAME ]
[ -M MATCH-SPEC ]

The remaining OPTIONS specify the type of command arguments to look for
during completion.  Any combination of these flags may be specified; the
result is a sorted list of all the possibilities.  The options are as
follows.
* Menu:

* Simple Flags::
* Flags with Arguments::
* Control Flags::


File: zsh.info,  Node: Simple Flags,  Next: Flags with Arguments,  Up: Option Flags

21.4.1 Simple Flags
-------------------

These produce completion lists made up by the shell itself:

-f
     Filenames and file system paths.

-/
     Just file system paths.

-c
     Command names, including aliases, shell functions, builtins and
     reserved words.

-F
     Function names.

-B
     Names of builtin commands.

-m
     Names of external commands.

-w
     Reserved words.

-a
     Alias names.

-R
     Names of regular (non-global) aliases.

-G
     Names of global aliases.

-d
     This can be combined with -F, -B, -w, -a, -R and -G to get names of
     disabled functions, builtins, reserved words or aliases.

-e
     This option (to show enabled commands) is in effect by default, but
     may be combined with -d; -de in combination with -F, -B, -w, -a, -R
     and -G will complete names of functions, builtins, reserved words
     or aliases whether or not they are disabled.

-o
     Names of shell options (see *note Options::).

-v
     Names of any variable defined in the shell.

-N
     Names of scalar (non-array) parameters.

-A
     Array names.

-I
     Names of integer variables.

-O
     Names of read-only variables.

-p
     Names of parameters used by the shell (including special
     parameters).

-Z
     Names of shell special parameters.

-E
     Names of environment variables.

-n
     Named directories.

-b
     Key binding names.

-j
     Job names: the first word of the job leader's command line.  This
     is useful with the kill builtin.

-r
     Names of running jobs.

-z
     Names of suspended jobs.

-u
     User names.


File: zsh.info,  Node: Flags with Arguments,  Next: Control Flags,  Prev: Simple Flags,  Up: Option Flags

21.4.2 Flags with Arguments
---------------------------

These have user supplied arguments to determine how the list of
completions is to be made up:

-k ARRAY
     Names taken from the elements of $ARRAY (note that the '$' does not
     appear on the command line).  Alternatively, the argument ARRAY
     itself may be a set of space- or comma-separated values in
     parentheses, in which any delimiter may be escaped with a
     backslash; in this case the argument should be quoted.  For
     example,

          compctl -k "(cputime filesize datasize stacksize
          	       coredumpsize resident descriptors)" limit

-g GLOBSTRING
     The GLOBSTRING is expanded using filename globbing; it should be
     quoted to protect it from immediate expansion.  The resulting
     filenames are taken as the possible completions.  Use '*(/)'
     instead of '*/' for directories.  The fignore special parameter is
     not applied to the resulting files.  More than one pattern may be
     given separated by blanks.  (Note that brace expansion is _not_
     part of globbing.  Use the syntax '(either|or)' to match
     alternatives.)

-s SUBSTSTRING
     The SUBSTSTRING is split into words and these words are than
     expanded using all shell expansion mechanisms (see *note
     Expansion::).  The resulting words are taken as possible
     completions.  The fignore special parameter is not applied to the
     resulting files.  Note that -g is faster for filenames.

-K FUNCTION
     Call the given function to get the completions.  Unless the name
     starts with an underscore, the function is passed two arguments:
     the prefix and the suffix of the word on which completion is to be
     attempted, in other words those characters before the cursor
     position, and those from the cursor position onwards.  The whole
     command line can be accessed with the -c and -l flags of the read
     builtin.  The function should set the variable reply to an array
     containing the completions (one completion per element); note that
     reply should not be made local to the function.  From such a
     function the command line can be accessed with the -c and -l flags
     to the read builtin.  For example,

          function whoson { reply=(`users`); }
          compctl -K whoson talk

     completes only logged-on users after 'talk'.  Note that 'whoson'
     must return an array, so 'reply=`users`' would be incorrect.

-H NUM PATTERN
     The possible completions are taken from the last NUM history lines.
     Only words matching PATTERN are taken.  If NUM is zero or negative
     the whole history is searched and if PATTERN is the empty string
     all words are taken (as with '*').  A typical use is

          compctl -D -f + -H 0 ''

     which forces completion to look back in the history list for a word
     if no filename matches.


File: zsh.info,  Node: Control Flags,  Prev: Flags with Arguments,  Up: Option Flags

21.4.3 Control Flags
--------------------

These do not directly specify types of name to be completed, but
manipulate the options that do:

-Q
     This instructs the shell not to quote any metacharacters in the
     possible completions.  Normally the results of a completion are
     inserted into the command line with any metacharacters quoted so
     that they are interpreted as normal characters.  This is
     appropriate for filenames and ordinary strings.  However, for
     special effects, such as inserting a backquoted expression from a
     completion array (-k) so that the expression will not be evaluated
     until the complete line is executed, this option must be used.

-P PREFIX
     The PREFIX is inserted just before the completed string; any
     initial part already typed will be completed and the whole PREFIX
     ignored for completion purposes.  For example,

          compctl -j -P "%" kill

     inserts a '%' after the kill command and then completes job names.

-S SUFFIX
     When a completion is found the SUFFIX is inserted after the
     completed string.  In the case of menu completion the suffix is
     inserted immediately, but it is still possible to cycle through the
     list of completions by repeatedly hitting the same key.

-W FILE-PREFIX
     With directory FILE-PREFIX: for command, file, directory and
     globbing completion (options -c, -f, -/, -g), the file prefix is
     implicitly added in front of the completion.  For example,

          compctl -/ -W ~/Mail maildirs

     completes any subdirectories to any depth beneath the directory
     ~/Mail, although that prefix does not appear on the command line.
     The FILE-PREFIX may also be of the form accepted by the -k flag,
     i.e.  the name of an array or a literal list in parenthesis.  In
     this case all the directories in the list will be searched for
     possible completions.

-q
     If used with a suffix as specified by the -S option, this causes
     the suffix to be removed if the next character typed is a blank or
     does not insert anything or if the suffix consists of only one
     character and the next character typed is the same character; this
     the same rule used for the AUTO_REMOVE_SLASH option.  The option is
     most useful for list separators (comma, colon, etc.).

-l CMD
     This option restricts the range of command line words that are
     considered to be arguments.  If combined with one of the extended
     completion patterns 'p[...]', 'r[...]', or 'R[...]'  (see *note
     Extended Completion:: below) the range is restricted to the range
     of arguments specified in the brackets.  Completion is then
     performed as if these had been given as arguments to the CMD
     supplied with the option.  If the CMD string is empty the first
     word in the range is instead taken as the command name, and command
     name completion performed on the first word in the range.  For
     example,

          compctl -x 'r[-exec,;]' -l '' -- find

     completes arguments between '-exec' and the following ';' (or the
     end of the command line if there is no such string) as if they were
     a separate command line.

-h CMD
     Normally zsh completes quoted strings as a whole.  With this
     option, completion can be done separately on different parts of
     such strings.  It works like the -l option but makes the completion
     code work on the parts of the current word that are separated by
     spaces.  These parts are completed as if they were arguments to the
     given CMD.  If CMD is the empty string, the first part is completed
     as a command name, as with -l.

-U
     Use the whole list of possible completions, whether or not they
     actually match the word on the command line.  The word typed so far
     will be deleted.  This is most useful with a function (given by the
     -K option) which can examine the word components passed to it (or
     via the read builtin's -c and -l flags) and use its own criteria to
     decide what matches.  If there is no completion, the original word
     is retained.  Since the produced possible completions seldom have
     interesting common prefixes and suffixes, menu completion is
     started immediately if AUTO_MENU is set and this flag is used.

-y FUNC-OR-VAR
     The list provided by FUNC-OR-VAR is displayed instead of the list
     of completions whenever a listing is required; the actual
     completions to be inserted are not affected.  It can be provided in
     two ways.  Firstly, if FUNC-OR-VAR begins with a $ it defines a
     variable, or if it begins with a left parenthesis a literal array,
     which contains the list.  A variable may have been set by a call to
     a function using the -K option.  Otherwise it contains the name of
     a function which will be executed to create the list.  The function
     will be passed as an argument list all matching completions,
     including prefixes and suffixes expanded in full, and should set
     the array reply to the result.  In both cases, the display list
     will only be retrieved after a complete list of matches has been
     created.

     Note that the returned list does not have to correspond, even in
     length, to the original set of matches, and may be passed as a
     scalar instead of an array.  No special formatting of characters is
     performed on the output in this case; in particular, newlines are
     printed literally and if they appear output in columns is
     suppressed.

-X EXPLANATION
     Print EXPLANATION when trying completion on the current set of
     options.  A '%n' in this string is replaced by the number of
     matches that were added for this explanation string.  The
     explanation only appears if completion was tried and there was no
     unique match, or when listing completions.  Explanation strings
     will be listed together with the matches of the group specified
     together with the -X option (using the -J or -V option).  If the
     same explanation string is given to multiple -X options, the string
     appears only once (for each group) and the number of matches shown
     for the '%n' is the total number of all matches for each of these
     uses.  In any case, the explanation string will only be shown if
     there was at least one match added for the explanation string.

     The sequences %B, %b, %S, %s, %U, and %u specify output attributes
     (bold, standout, and underline), %F, %f, %K, %k specify foreground
     and background colours, and %{...%} can be used to include literal
     escape sequences as in prompts.

-Y EXPLANATION
     Identical to -X, except that the EXPLANATION first undergoes
     expansion following the usual rules for strings in double quotes.
     The expansion will be carried out after any functions are called
     for the -K or -y options, allowing them to set variables.

-t CONTINUE
     The CONTINUE-string contains a character that specifies which set
     of completion flags should be used next.  It is useful:

     (i) With -T, or when trying a list of pattern completions, when
     compctl would usually continue with ordinary processing after
     finding matches; this can be suppressed with '-tn'.

     (ii) With a list of alternatives separated by +, when compctl would
     normally stop when one of the alternatives generates matches.  It
     can be forced to consider the next set of completions by adding
     '-t+' to the flags of the alternative before the '+'.

     (iii) In an extended completion list (see below), when compctl
     would normally continue until a set of conditions succeeded, then
     use only the immediately following flags.  With '-t-', compctl will
     continue trying extended completions after the next '-'; with '-tx'
     it will attempt completion with the default flags, in other words
     those before the '-x'.

-J NAME
     This gives the name of the group the matches should be placed in.
     Groups are listed and sorted separately; likewise, menu completion
     will offer the matches in the groups in the order in which the
     groups were defined.  If no group name is explicitly given, the
     matches are stored in a group named default.  The first time a
     group name is encountered, a group with that name is created.
     After that all matches with the same group name are stored in that
     group.

     This can be useful with non-exclusive alternative completions.  For
     example, in

          compctl -f -J files -t+ + -v -J variables foo

     both files and variables are possible completions, as the -t+
     forces both sets of alternatives before and after the + to be
     considered at once.  Because of the -J options, however, all files
     are listed before all variables.

-V NAME
     Like -J, but matches within the group will not be sorted in
     listings nor in menu completion.  These unsorted groups are in a
     different name space from the sorted ones, so groups defined as -J
     files and -V files are distinct.

-1
     If given together with the -V option, makes only consecutive
     duplicates in the group be removed.  Note that groups with and
     without this flag are in different name spaces.

-2
     If given together with the -J or -V option, makes all duplicates be
     kept.  Again, groups with and without this flag are in different
     name spaces.

-M MATCH-SPEC
     This defines additional matching control specifications that should
     be used only when testing words for the list of flags this flag
     appears in.  The format of the MATCH-SPEC string is described in
     *note Completion Matching Control::.


File: zsh.info,  Node: Alternative Completion,  Next: Extended Completion,  Prev: Option Flags,  Up: Completion Using compctl

21.5 Alternative Completion
===========================

compctl [ -CDT ] OPTIONS + OPTIONS [ + ... ] [ + ] COMMAND ...

The form with '+' specifies alternative options.  Completion is tried
with the options before the first '+'.  If this produces no matches
completion is tried with the flags after the '+' and so on.  If there
are no flags after the last '+' and a match has not been found up to
that point, default completion is tried.  If the list of flags contains
a -t with a + character, the next list of flags is used even if the
current list produced matches.

