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* ZSH: (zsh).                     The Z Shell Manual.
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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 ... ] -- [ -l ] [ -i PATS ] [ -s PAIR ]
           [ HELPSPEC ...]
     This function can be used to give a complete specification for
     completion for a command whose arguments follow standard UNIX
     option and argument conventions.

     _Options Overview_

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

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

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

     The options of _arguments have the following meanings:


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

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

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

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

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

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

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

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

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


               foobar -x -- -y

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

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

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

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


     _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.

     _Grouping Options_

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


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

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


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

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

     _Specifying Multiple Sets of Arguments_

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

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


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

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

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

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

     _Deriving SPEC forms from the help output_

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

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

     For example:


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

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


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

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

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

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

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

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


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

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

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

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


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

     _Miscellaneous notes_

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

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


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

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

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

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

     The last two descriptions say what should be completed as
     arguments.  The first describes the first argument as a
     `POSTSCRIPT FILE' and makes files ending in `ps' or `eps' be
     completed.  The last description gives all other arguments the
     description `PAGE 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 [ -l ] [ -p ] TAG STRING ...
     This function provides a mechanism for the user to override the
     use of an external command.  It looks up the command style with
     the supplied TAG.  If the style is set, its value is used as the
     command to execute.  The STRINGs from the call to _call_program,
     or from the style if set, are concatenated with spaces between
     them and the resulting string is evaluated.  The return status is
     the return status of the command called.

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

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

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

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

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

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

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

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

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

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

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

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

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


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


_describe [-12JVx] [ -oO | -t TAG ] DESCR NAME1 [ NAME2 ] [ OPT ... ]
          [ -- NAME1 [ NAME2 ] [ OPT ... ] ... ]
     This function associates completions with descriptions.  Multiple
     groups separated by -- can be supplied, potentially with different
     completion options OPTs.

     The DESCR is taken as a string to display above the matches if the
     format style for the descriptions tag is set.  This is followed by
     one or two names of arrays followed by options to pass to compadd.
     The array NAME1 contains the possible completions with their
     descriptions in the form `COMPLETION:DESCRIPTION'.  Any literal
     colons in COMPLETION must be quoted with a backslash.  If a NAME2
     is given, it should have the same number of elements as NAME1; in
     this case the corresponding elements are added as possible
     completions instead of the COMPLETION strings from NAME1.  The
     completion list will retain the descriptions from NAME1.  Finally,
     a set of completion options can appear.

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

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

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

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

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

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

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

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

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

     If _description is called with more than three arguments, the
     additional SPECs should be of the form `CHAR:STR'.  These supply
     escape sequence replacements for the format style: every
     appearance of `%CHAR' will be replaced by STRING.

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

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

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


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

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

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


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

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


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

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

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


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

    -n PLUGIN
          Complete aliases from PLUGIN.


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

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

     _Writing plugins_

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

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

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

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


          compdef _gnu_generic foo bar

     after the call to compinit.

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

_guard [ OPTIONS ] PATTERN DESCR
     This function displays DESCR if PATTERN matches the string to be
     completed.  It is intended to be used in the ACTION for the
     specifications passed to _arguments and similar functions.

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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


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

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


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

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

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

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

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

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

     All other arguments are passed to the compadd builtin.

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

     The options accepted by both _path_files and _files are:


    -f
          Complete all filenames.  This is the default.

    -/
          Specifies that only directories should be completed.

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

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

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


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

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

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

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

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

     If the `-r NAME' is given, the LABEL picked is stored in the
     parameter named NAME.

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

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

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

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

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


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

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

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

    /PATTERN/+ [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to `/PATTERN/ ...' but the left part of the
          command line string (i.e. the part already matched by
          previous patterns) is also considered part of the completion
          target.

    /PATTERN/- [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to `/PATTERN/ ...' but the ACTIONs of the
          current and previously matched patterns are ignored even if
          the following `PATTERN' matches the empty string.

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

    SPEC #
          This allows any number of repetitions of SPEC.

    SPEC SPEC
          The two SPECs are to be matched one after the other as
          described above.

    SPEC | SPEC
          Either of the two SPECs can be matched.


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

     Examples:


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

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


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

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


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

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


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

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

     

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

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

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

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

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

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

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

     For example:


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

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

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


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

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

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

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


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

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

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

     See _store_cache below for more details.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

_values [ -O NAME ] [ -s SEP ] [ -S SEP ] [ -wC ] DESC SPEC ...
     This is used to complete arbitrary keywords (values) and their
     arguments, or lists of such combinations.

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

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

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

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

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

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

     Example:


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

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

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

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

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


          local context state state_descr line
          typeset -A val_args

     when using an action of the form `->STRING'.  With this function
     the context parameter will be set to the name of the value whose
     argument is to be completed.  Note that for _values, the state and
     state_descr are scalars rather than arrays.  Only a single
     matching state is returned.

     Note also that _values normally adds the character used as the
     separator between values as an auto-removable suffix (similar to a
     `/' after a directory).  However, this is not possible for a
     `->STRING' action as the matches for the argument are generated by
     the calling function.  To get the usual behaviour, the calling
     function can add the separator X as a suffix by passing the
     options `-qS X' either directly or indirectly to compadd.

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

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

     The arguments to _wanted are the same as those to _requested, i.e.
     arguments to be passed to _description.  However, in this case the
     COMMAND is not optional;  all the processing of tags, including
     the loop over both tags and tag labels and the generation of
     matches, is carried out automatically by _wanted.

     Hence to offer only one tag and immediately add the corresponding
     matches with the given description:


          local expl
          _wanted tag expl 'description' \
              compadd 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.




File: zsh.info,  Node: Extended Completion,  Next: Example,  Prev: Alternative Completion,  Up: Completion Using compctl

Additional options are available that restrict completion to some part
of the command line; this is referred to as `extended completion'.



21.6 Extended Completion
========================


compctl [ -CDT ] OPTIONS -x PATTERN OPTIONS - ... --

        [ COMMAND ... ]

compctl [ -CDT ] OPTIONS [ -x PATTERN OPTIONS - ... -- ]

        [ + OPTIONS [ -x ... -- ] ... [+] ] [ COMMAND ... ]


The form with `-x' specifies extended completion for the commands
given; as shown, it may be combined with alternative completion using
`+'.  Each PATTERN is examined in turn; when a match is found, the
corresponding OPTIONS, as described in *Note Option Flags:: above, are
used to generate possible completions.  If no PATTERN matches, the
OPTIONS given before the -x are used.

Note that each pattern should be supplied as a single argument and
should be quoted to prevent expansion of metacharacters by the shell.

A PATTERN is built of sub-patterns separated by commas; it matches if
at least one of these sub-patterns matches (they are `or'ed). These
sub-patterns are in turn composed of other sub-patterns separated by
white spaces which match if all of the sub-patterns match (they are
`and'ed).  An element of the sub-patterns is of the form `C[...][...]',
where the pairs of brackets may be repeated as often as necessary, and
matches if any of the sets of brackets match (an `or').  The example
below makes this clearer.

The elements may be any of the following:


s[STRING]...
     Matches if the current word on the command line starts with one of
     the strings given in brackets.  The STRING is not removed and is
     not part of the completion.

S[STRING]...
     Like s[STRING] except that the STRING is part of the completion.

p[FROM,TO]...
     Matches if the number of the current word is between one of the
     FROM and TO pairs inclusive. The comma and TO are optional; TO
     defaults to the same value as FROM.  The numbers may be negative:
     -N refers to the N'th last word on the line.

c[OFFSET,STRING]...
     Matches if the STRING matches the word offset by OFFSET from the
     current word position.  Usually OFFSET will be negative.

C[OFFSET,PATTERN]...
     Like c but using pattern matching instead.

w[INDEX,STRING]...
     Matches if the word in position INDEX is equal to the
     corresponding STRING.  Note that the word count is made after any
     alias expansion.

W[INDEX,PATTERN]...
     Like w but using pattern matching instead.

n[INDEX,STRING]...
     Matches if the current word contains STRING.  Anything up to and
     including the INDEXth occurrence of this string will not be
     considered part of the completion, but the rest will.  INDEX may
     be negative to count from the end: in most cases, INDEX will be 1
     or -1.  For example,


          compctl -s '`users`' -x 'n[1,@]' -k hosts -- talk

     will usually complete usernames, but if you insert an @ after the
     name, names from the array HOSTS (assumed to contain hostnames,
     though you must make the array yourself) will be completed.  Other
     commands such as rcp can be handled similarly.

N[INDEX,STRING]...
     Like n except that the string will be taken as a character class.
     Anything up to and including the INDEXth occurrence of any of the
     characters in STRING will not be considered part of the completion.

m[MIN,MAX]...
     Matches if the total number of words lies between MIN and MAX
     inclusive.

r[STR1,STR2]...
     Matches if the cursor is after a word with prefix STR1.  If there
     is also a word with prefix STR2 on the command line after the one
     matched by STR1 it matches only if the cursor is before this word.
     If the comma and STR2 are omitted, it matches if the cursor is
     after a word with prefix STR1.

R[STR1,STR2]...
     Like r but using pattern matching instead.

q[STR]...
     Matches the word currently being completed is in single quotes and
     the STR begins with the letter `s', or if completion is done in
     double quotes and STR starts with the letter `d', or if completion
     is done in backticks and STR starts with a `b'.




File: zsh.info,  Node: Example,  Prev: Extended Completion,  Up: Completion Using compctl

21.7 Example
============


     compctl -u -x 's[+] c[-1,-f],s[-f+]' \
       -g '~/Mail/*(:t)' - 's[-f],c[-1,-f]' -f -- mail

This is to be interpreted as follows:

If the current command is mail, then



     if ((the current word begins with + and the previous word is -f)
     or (the current word begins with -f+)), then complete the
     non-directory part (the `:t' glob modifier) of files in the
     directory ~/Mail; else

     if the current word begins with -f or the previous word was -f,
     then complete any file; else

     complete user names.



File: zsh.info,  Node: Zsh Modules,  Next: Calendar Function System,  Prev: Completion Using compctl,  Up: Top

22 Zsh Modules
**************



22.1 Description
================

Some optional parts of zsh are in modules, separate from the core of
the shell.  Each of these modules may be linked in to the shell at
build time, or can be dynamically linked while the shell is running if
the installation supports this feature.  Modules are linked at runtime
with the zmodload command, see *Note Shell Builtin Commands::.

The modules that are bundled with the zsh distribution are:


zsh/attr
     Builtins for manipulating extended attributes (xattr).

zsh/cap
     Builtins for manipulating POSIX.1e (POSIX.6) capability
     (privilege) sets.

zsh/clone
     A builtin that can clone a running shell onto another terminal.

zsh/compctl
     The compctl builtin for controlling completion.

zsh/complete
     The basic completion code.

zsh/complist
     Completion listing extensions.

zsh/computil
     A module with utility builtins needed for the shell function based
     completion system.

zsh/curses
     curses windowing commands

zsh/datetime
     Some date/time commands and parameters.

zsh/db/gdbm
     Builtins for managing associative array parameters tied to GDBM
     databases.

zsh/deltochar
     A ZLE function duplicating EMACS' zap-to-char.

zsh/example
     An example of how to write a module.

zsh/files
     Some basic file manipulation commands as builtins.

zsh/langinfo
     Interface to locale information.

zsh/mapfile
     Access to external files via a special associative array.

zsh/mathfunc
     Standard scientific functions for use in mathematical evaluations.

zsh/nearcolor
     Map colours to the nearest colour in the available palette.

zsh/newuser
     Arrange for files for new users to be installed.

zsh/parameter
     Access to internal hash tables via special associative arrays.

zsh/pcre
     Interface to the PCRE library.

zsh/param/private
     Builtins for managing private-scoped parameters in function
     context.

zsh/regex
     Interface to the POSIX regex library.

zsh/sched
     A builtin that provides a timed execution facility within the
     shell.

zsh/net/socket
     Manipulation of Unix domain sockets

zsh/stat
     A builtin command interface to the stat system call.

zsh/system
     A builtin interface to various low-level system features.

zsh/net/tcp
     Manipulation of TCP sockets

zsh/termcap
     Interface to the termcap database.

zsh/terminfo
     Interface to the terminfo database.

zsh/zftp
     A builtin FTP client.

zsh/zle
     The Zsh Line Editor, including the bindkey and vared builtins.

zsh/zleparameter
     Access to internals of the Zsh Line Editor via parameters.

zsh/zprof
     A module allowing profiling for shell functions.

zsh/zpty
     A builtin for starting a command in a pseudo-terminal.

zsh/zselect
     Block and return when file descriptors are ready.

zsh/zutil
     Some utility builtins, e.g. the one for supporting configuration
     via styles.


* Menu:

* The zsh/attr Module::
* The zsh/cap Module::
* The zsh/clone Module::
* The zsh/compctl Module::
* The zsh/complete Module::
* The zsh/complist Module::
* The zsh/computil Module::
* The zsh/curses Module::
* The zsh/datetime Module::
* The zsh/db/gdbm Module::
* The zsh/deltochar Module::
* The zsh/example Module::
* The zsh/files Module::
* The zsh/langinfo Module::
* The zsh/mapfile Module::
* The zsh/mathfunc Module::
* The zsh/nearcolor Module::
* The zsh/newuser Module::
* The zsh/parameter Module::
* The zsh/pcre Module::
* The zsh/param/private Module::
* The zsh/regex Module::
* The zsh/sched Module::
* The zsh/net/socket Module::
* The zsh/stat Module::
* The zsh/system Module::
* The zsh/net/tcp Module::
* The zsh/termcap Module::
* The zsh/terminfo Module::
* The zsh/zftp Module::
* The zsh/zle Module::
* The zsh/zleparameter Module::
* The zsh/zprof Module::
* The zsh/zpty Module::
* The zsh/zselect Module::
* The zsh/zutil Module::


File: zsh.info,  Node: The zsh/attr Module,  Next: The zsh/cap Module,  Up: Zsh Modules

22.2 The zsh/attr Module
========================



   The zsh/attr module is used for manipulating extended attributes.
The -h option causes all commands to operate on symbolic links instead
of their targets.  The builtins in this module are:


zgetattr [ -h ] FILENAME ATTRIBUTE [ PARAMETER ]
     Get the extended attribute ATTRIBUTE from the specified FILENAME.
     If the optional argument PARAMETER is given, the attribute is set
     on that parameter instead of being printed to stdout.

zsetattr [ -h ] FILENAME ATTRIBUTE VALUE
     Set the extended attribute ATTRIBUTE on the specified FILENAME to
     VALUE.

zdelattr [ -h ] FILENAME ATTRIBUTE
     Remove the extended attribute ATTRIBUTE from the specified
     FILENAME.

zlistattr [ -h ] FILENAME [ PARAMETER ]
     List the extended attributes currently set on the specified
     FILENAME. If the optional argument PARAMETER is given, the list of
     attributes is set on that parameter instead of being printed to
     stdout.


zgetattr and zlistattr allocate memory dynamically.  If the attribute
or list of attributes grows between the allocation and the call to get
them, they return 2.  On all other errors, 1 is returned.  This allows
the calling function to check for this case and retry.


File: zsh.info,  Node: The zsh/cap Module,  Next: The zsh/clone Module,  Prev: The zsh/attr Module,  Up: Zsh Modules

22.3 The zsh/cap Module
=======================



   The zsh/cap module is used for manipulating POSIX.1e (POSIX.6)
capability sets.  If the operating system does not support this
interface, the builtins defined by this module will do nothing.  The
builtins in this module are:


cap [ CAPABILITIES ]
     Change the shell's process capability sets to the specified
     CAPABILITIES, otherwise display the shell's current capabilities.

getcap FILENAME ...
     This is a built-in implementation of the POSIX standard utility.
     It displays the capability sets on each specified FILENAME.

setcap CAPABILITIES FILENAME ...
     This is a built-in implementation of the POSIX standard utility.
     It sets the capability sets on each specified FILENAME to the
     specified CAPABILITIES.



File: zsh.info,  Node: The zsh/clone Module,  Next: The zsh/compctl Module,  Prev: The zsh/cap Module,  Up: Zsh Modules

22.4 The zsh/clone Module
=========================



   The zsh/clone module makes available one builtin command:


clone TTY
     Creates a forked instance of the current shell, attached to the
     specified TTY.  In the new shell, the PID, PPID and TTY special
     parameters are changed appropriately.  $! is set to zero in the new
     shell, and to the new shell's PID in the original shell.

     The return status of the builtin is zero in both shells if
     successful, and non-zero on error.

     The target of clone should be an unused terminal, such as an
     unused virtual console or a virtual terminal created by


          xterm -e sh -c 'trap : INT QUIT TSTP; tty;
                  while :; do sleep 100000000; done'

     Some words of explanation are warranted about this long xterm
     command line: when doing clone on a pseudo-terminal, some other
     session ("session" meant as a unix session group, or SID) is
     already owning the terminal. Hence the cloned zsh cannot acquire
     the pseudo-terminal as a controlling tty. That means two things:


        * the job control signals will go to the sh-started-by-xterm
          process group (that's why we disable INT QUIT and TSTP with
          trap; otherwise the while loop could get suspended or killed)

        * the cloned shell will have job control disabled, and the job
          control keys (control-C, control-\ and control-Z) will not
          work.

     This does not apply when cloning to an _unused_ vc.

     Cloning to a used (and unprepared) terminal will result in two
     processes reading simultaneously from the same terminal, with
     input bytes going randomly to either process.

     clone is mostly useful as a shell built-in replacement for openvt.



File: zsh.info,  Node: The zsh/compctl Module,  Next: The zsh/complete Module,  Prev: The zsh/clone Module,  Up: Zsh Modules

22.5 The zsh/compctl Module
===========================



   The zsh/compctl module makes available two builtin commands. compctl,
is the old, deprecated way to control completions for ZLE.  See *Note
Completion Using compctl::.  The other builtin command, compcall can be
used in user-defined completion widgets, see *Note Completion Widgets::.


File: zsh.info,  Node: The zsh/complete Module,  Next: The zsh/complist Module,  Prev: The zsh/compctl Module,  Up: Zsh Modules

22.6 The zsh/complete Module
============================



   The zsh/complete module makes available several builtin commands
which can be used in user-defined completion widgets, see *Note
Completion Widgets::.


File: zsh.info,  Node: The zsh/complist Module,  Next: The zsh/computil Module,  Prev: The zsh/complete Module,  Up: Zsh Modules

22.7 The zsh/complist Module
============================



   The zsh/complist module offers three extensions to completion
listings: the ability to highlight matches in such a list, the ability
to scroll through long lists and a different style of menu completion.



22.7.1 Colored completion listings
----------------------------------

Whenever one of the parameters ZLS_COLORS or ZLS_COLOURS is set and the
zsh/complist module is loaded or linked into the shell, completion
lists will be colored.  Note, however, that complist will not
automatically be loaded if it is not linked in:  on systems with
dynamic loading, `zmodload zsh/complist' is required.

The parameters ZLS_COLORS and ZLS_COLOURS describe how matches are
highlighted.  To turn on highlighting an empty value suffices, in which
case all the default values given below will be used.  The format of
the value of these parameters is the same as used by the GNU version of
the ls command: a colon-separated list of specifications of the form
`NAME=VALUE'.  The NAME may be one of the following strings, most of
which specify file types for which the VALUE will be used.  The strings
and their default values are:


no 0
     for normal text (i.e. when displaying something other than a
     matched file)

fi 0
     for regular files

di 32
     for directories

ln 36
     for symbolic links.  If this has the special value target,
     symbolic links are dereferenced and the target file used to
     determine the display format.

pi 31
     for named pipes (FIFOs)

so 33
     for sockets

bd 44;37
     for block devices

cd 44;37
     for character devices

or NONE
     for a symlink to nonexistent file (default is the value defined
     for ln)

mi NONE
     for a non-existent file (default is the value defined for fi);
     this code is currently not used

su 37;41
     for files with setuid bit set

sg 30;43
     for files with setgid bit set

tw 30;42
     for world writable directories with sticky bit set

ow 34;43
     for world writable directories without sticky bit set

sa NONE
     for files with an associated suffix alias; this is only tested
     after specific suffixes, as described below

st 37;44
     for directories with sticky bit set but not world writable

ex 35
     for executable files

lc \e[
     for the left code (see below)

rc m
     for the right code

tc 0
     for the character indicating the file type  printed after
     filenames if the LIST_TYPES option is set

sp 0
     for the spaces printed after matches to align the next column

ec NONE
     for the end code


Apart from these strings, the NAME may also be an asterisk (`*')
followed by any string. The VALUE given for such a string will be used
for all files whose name ends with the string.  The NAME may also be an
equals sign (`=') followed by a pattern; the EXTENDED_GLOB option will
be turned on for evaluation of the pattern.  The VALUE given for this
pattern will be used for all matches (not just filenames) whose display
string are matched by the pattern.  Definitions for the form with the
leading equal sign take precedence over the values defined for file
types, which in turn take precedence over the form with the leading
asterisk (file extensions).

The leading-equals form also allows different parts of the displayed
strings to be colored differently.  For this, the pattern has to use the
`(#b)' globbing flag and pairs of parentheses surrounding the parts of
the strings that are to be colored differently.  In this case the VALUE
may consist of more than one color code separated by equal signs.  The
first code will be used for all parts for which no explicit code is
specified and the following codes will be used for the parts matched by
the sub-patterns in parentheses.  For example, the specification
`=(#b)(?)*(?)=0=3=7' will be used for all matches which are at least
two characters long and will use the code `3' for the first character,
`7' for the last character and `0' for the rest.

All three forms of NAME may be preceded by a pattern in parentheses.
If this is given, the VALUE will be used only for matches in groups
whose names are matched by the pattern given in the parentheses.  For
example, `(g*)m*=43' highlights all matches beginning with `m' in
groups whose names  begin with `g' using the color code `43'.  In case
of the `lc', `rc', and `ec' codes, the group pattern is ignored.

Note also that all patterns are tried in the order in which they appear
in the parameter value until the first one matches which is then used.
Patterns may be matched against completions, descriptions (possibly
with spaces appended for padding), or lines consisting of a completion
followed by a description.  For consistent coloring it may be necessary
to use more than one pattern or a pattern with backreferences.

When printing a match, the code prints the value of lc, the value for
the file-type or the last matching specification with a `*', the value
of rc, the string to display for the match itself, and then the value
of ec if that is defined or the values of lc, no, and rc if ec is not
defined.

The default values are ISO 6429 (ANSI) compliant and can be used on
vt100 compatible terminals such as xterms.  On monochrome terminals the
default values will have no visible effect.  The colors function from
the contribution can be used to get associative arrays containing the
codes for ANSI terminals (see *Note Other Functions::).  For example,
after loading colors, one could use `$color[red]' to get the code for
foreground color red and `$color[bg-green]' for the code for background
color green.

If the completion system invoked by compinit is used, these parameters
should not be set directly because the system controls them itself.
Instead, the list-colors style should be used (see *Note Completion
System Configuration::).



22.7.2 Scrolling in completion listings
---------------------------------------

To enable scrolling through a completion list, the LISTPROMPT parameter
must be set.  Its value will be used as the prompt; if it is the empty
string, a default prompt will be used.  The value may contain escapes
of the form `%x'.  It supports the escapes `%B', `%b', `%S', `%s',
`%U', `%u', `%F', `%f', `%K', `%k' and `%{...%}' used also in shell
prompts as well as three pairs of additional sequences: a `%l' or `%L'
is replaced by the number of the last line shown and the total number
of lines in the form `NUMBER/TOTAL'; a `%m' or `%M' is replaced with
the number of the last match shown and the total number of matches; and
`%p' or `%P' is replaced with `Top', `Bottom' or the position of the
first line shown in percent of the total number of lines, respectively.
In each of these cases the form with the uppercase letter will be
replaced with a string of fixed width, padded to the right with spaces,
while the lowercase form will not be padded.

If the parameter LISTPROMPT is set, the completion code will not ask if
the list should be shown.  Instead it immediately starts displaying the
list, stopping after the first screenful, showing the prompt at the
bottom, waiting for a keypress after temporarily switching to the
listscroll keymap.  Some of the zle functions have a special meaning
while scrolling lists:


send-break
     stops listing discarding the key pressed

accept-line, down-history, down-line-or-history
down-line-or-search, vi-down-line-or-history
     scrolls forward one line

complete-word, menu-complete, expand-or-complete
expand-or-complete-prefix, menu-complete-or-expand
     scrolls forward one screenful

accept-search
     stop listing but take no other action


Every other character stops listing and immediately processes the key
as usual.  Any key that is not bound in the listscroll keymap or that
is bound to undefined-key is looked up in the keymap currently selected.

As for the ZLS_COLORS and ZLS_COLOURS parameters, LISTPROMPT should not
be set directly when using the shell function based completion system.
Instead, the list-prompt style should be used.



22.7.3 Menu selection
---------------------

The zsh/complist module also offers an alternative style of selecting
matches from a list, called menu selection, which can be used if the
shell is set up to return to the last prompt after showing a completion
list (see the ALWAYS_LAST_PROMPT option in *Note Options::).

Menu selection can be invoked directly by the widget menu-select
defined by this module.  This is a standard ZLE widget that can be
bound to a key in the usual way as described in *Note Zsh Line Editor::.

Alternatively, the parameter MENUSELECT can be set to an integer, which
gives the minimum number of matches that must be present before menu
selection is automatically turned on.  This second method requires that
menu completion be started, either directly from a widget such as
menu-complete, or due to one of the options MENU_COMPLETE or AUTO_MENU
being set.  If MENUSELECT is set, but is 0, 1 or empty, menu selection
will always be started during an ambiguous menu completion.

When using the completion system based on shell functions, the
MENUSELECT parameter should not be used (like the ZLS_COLORS and
ZLS_COLOURS parameters described above).  Instead, the menu style
should be used with the select=... keyword.

After menu selection is started, the matches will be listed. If there
are more matches than fit on the screen, only the first screenful is
shown.  The matches to insert into the command line can be selected
from this list.  In the list one match is highlighted using the value
for ma from the ZLS_COLORS or ZLS_COLOURS parameter.  The default value
for this is `7' which forces the selected match to be highlighted using
standout mode on a vt100-compatible terminal.  If neither ZLS_COLORS
nor ZLS_COLOURS is set, the same terminal control sequence as for the
`%S' escape in prompts is used.

If there are more matches than fit on the screen and the parameter
MENUPROMPT is set, its value will be shown below the matches.  It
supports the same escape sequences as LISTPROMPT, but the number of the
match or line shown will be that of the one where the mark is placed.
If its value is the empty string, a default prompt will be used.

The MENUSCROLL parameter can be used to specify how the list is
scrolled.  If the parameter is unset, this is done line by line, if it
is set to `0' (zero), the list will scroll half the number of lines of
the screen.  If the value is positive, it gives the number of lines to
scroll and if it is negative, the list will be scrolled the number of
lines of the screen minus the (absolute) value.

As for the ZLS_COLORS, ZLS_COLOURS and LISTPROMPT parameters, neither
MENUPROMPT nor MENUSCROLL should be set directly when using the shell
function based completion system.  Instead, the select-prompt and
select-scroll styles should be used.

The completion code sometimes decides not to show all of the matches in
the list.  These hidden matches are either matches for which the
completion function which added them explicitly requested that they not
appear in the list (using the -n option of the compadd builtin command)
or they are matches which duplicate a string already in the list
(because they differ only in things like prefixes or suffixes that are
not displayed).  In the list used for menu selection, however, even
these matches are shown so that it is possible to select them.  To
highlight such matches the hi and du capabilities in the ZLS_COLORS and
ZLS_COLOURS parameters are supported for hidden matches of the first
and second kind, respectively.

Selecting matches is done by moving the mark around using the zle
movement functions.  When not all matches can be shown on the screen at
the same time, the list will scroll up and down when crossing the top or
bottom line.  The following zle functions have special meaning during
menu selection.  Note that the following always perform the same task
within the menu selection map and cannot be replaced by user defined
widgets, nor can the set of functions be extended:


accept-line, accept-search
     accept the current match and leave menu selection (but do not
     cause the command line to be accepted)

send-break
     leaves menu selection and restores the previous contents of the
     command line

redisplay, clear-screen
     execute their normal function without leaving menu selection

accept-and-hold, accept-and-menu-complete
     accept the currently inserted match and continue selection
     allowing to select the next match to insert into the line

accept-and-infer-next-history
     accepts the current match and then tries completion with menu
     selection again;  in the case of files this allows one to select a
     directory and immediately attempt to complete files in it;  if
     there are no matches, a message is shown and one can use undo to
     go back to completion on the previous level, every other key
     leaves menu selection (including the other zle functions which are
     otherwise special during menu selection)

undo
     removes matches inserted during the menu selection by one of the
     three functions before

down-history, down-line-or-history
vi-down-line-or-history,  down-line-or-search
     moves the mark one line down

up-history, up-line-or-history
vi-up-line-or-history, up-line-or-search
     moves the mark one line up

forward-char, vi-forward-char
     moves the mark one column right

backward-char, vi-backward-char
     moves the mark one column left

forward-word, vi-forward-word
vi-forward-word-end, emacs-forward-word
     moves the mark one screenful down

backward-word, vi-backward-word, emacs-backward-word
     moves the mark one screenful up

vi-forward-blank-word, vi-forward-blank-word-end
     moves the mark to the first line of the next group of matches

vi-backward-blank-word
     moves the mark to the last line of the previous group of matches

beginning-of-history
     moves the mark to the first line

end-of-history
     moves the mark to the last line

beginning-of-buffer-or-history, beginning-of-line
beginning-of-line-hist, vi-beginning-of-line
     moves the mark to the leftmost column

end-of-buffer-or-history, end-of-line
end-of-line-hist, vi-end-of-line
     moves the mark to the rightmost column

complete-word, menu-complete, expand-or-complete
expand-or-complete-prefix, menu-expand-or-complete
     moves the mark to the next match

reverse-menu-complete
     moves the mark to the previous match

vi-insert
     this toggles between normal and interactive mode; in interactive
     mode the keys bound to self-insert and self-insert-unmeta insert
     into the command line as in normal editing mode but without leaving
     menu selection; after each character completion is tried again and
     the list changes to contain only the new matches; the completion
     widgets make the longest unambiguous string be inserted in the
     command line and undo and backward-delete-char go back to the
     previous set of matches

history-incremental-search-forward
history-incremental-search-backward
     this starts incremental searches in the list of completions
     displayed; in this mode, accept-line only leaves incremental
     search, going back to the normal menu selection mode


All movement functions wrap around at the edges; any other zle function
not listed leaves menu selection and executes that function.  It is
possible to make widgets in the above list do the same by using the
form of the widget with a `.' in front.  For example, the widget
`.accept-line' has the effect of leaving menu selection and accepting
the entire command line.

During this selection the widget uses the keymap menuselect.  Any key
that is not defined in this keymap or that is bound to undefined-key is
looked up in the keymap currently selected.  This is used to ensure
that the most important keys used during selection (namely the cursor
keys, return, and TAB) have sensible defaults.  However, keys in the
menuselect keymap can be modified directly using the bindkey builtin
command (see *Note The zsh/zle Module::). For example, to make the
return key leave menu selection without accepting the match currently
selected one could call


     bindkey -M menuselect '^M' send-break

after loading the zsh/complist module.


File: zsh.info,  Node: The zsh/computil Module,  Next: The zsh/curses Module,  Prev: The zsh/complist Module,  Up: Zsh Modules

22.8 The zsh/computil Module
============================



   The zsh/computil module adds several builtin commands that are used
by some of the completion functions in the completion system based on
shell functions (see *Note Completion System:: ).  Except for compquote
these builtin commands are very specialised and thus not very
interesting when writing your own completion functions.  In summary,
these builtin commands are:


comparguments
     This is used by the _arguments function to do the argument and
     command line parsing.  Like compdescribe it has an option -i to do
     the parsing and initialize some internal state and various options
     to access the state information to decide what should be completed.

compdescribe
     This is used by the _describe function to build the displays for
     the matches and to get the strings to add as matches with their
     options.  On the first call one of the options -i or -I should be
     supplied as the first argument.  In the first case, display
     strings without the descriptions will be generated, in the second
     case, the string used to separate the matches from their
     descriptions must be given as the second argument and the
     descriptions (if any) will be shown.  All other arguments are like
     the definition arguments to _describe itself.

     Once compdescribe has been called with either the -i or the -I
     option, it can be repeatedly called with the -g option and the
     names of four parameters as its arguments.  This will step through
     the different sets of matches and store the value of
     compstate[list] in the first scalar, the options for compadd in
     the second array, the matches in the third array, and the strings
     to be displayed in the completion listing in the fourth array.
     The arrays may then be directly given to compadd to register the
     matches with the completion code.

compfiles
     Used by the _path_files function to optimize complex recursive
     filename generation (globbing).  It does three things.  With the
     -p and -P options it builds the glob patterns to use, including
     the paths already handled and trying to optimize the patterns with
     respect to the prefix and suffix from the line and the match
     specification currently used.  The -i option does the directory
     tests for the ignore-parents style and the -r option tests if a
     component for some of the matches are equal to the string on the
     line and removes all other matches if that is true.

compgroups
     Used by the _tags function to implement the internals of the
     group-order style.  This only takes its arguments as names of
     completion groups and creates the groups for it (all six types:
     sorted and unsorted, both without removing duplicates, with
     removing all duplicates and with removing consecutive duplicates).

compquote [ -p ] NAMES ...
     There may be reasons to write completion functions that have to add
     the matches using the -Q option to compadd and perform quoting
     themselves.  Instead of interpreting the first character of the
     all_quotes key of the compstate special association and using the
     q flag for parameter expansions, one can use this builtin command.
     The arguments are the names of scalar or array parameters and the
     values of these parameters are quoted as needed for the innermost
     quoting level.  If the -p option is given, quoting is done as if
     there is some prefix before the values of the parameters, so that
     a leading equal sign will not be quoted.

     The return status is non-zero in case of an error and zero
     otherwise.

comptags
comptry
     These implement the internals of the tags mechanism.

compvalues
     Like comparguments, but for the _values function.



File: zsh.info,  Node: The zsh/curses Module,  Next: The zsh/datetime Module,  Prev: The zsh/computil Module,  Up: Zsh Modules

22.9 The zsh/curses Module
==========================



   The zsh/curses module makes available one builtin command and
various parameters.



22.9.1 Builtin
--------------


zcurses init
zcurses end
zcurses addwin TARGETWIN NLINES NCOLS BEGIN_Y BEGIN_X [ PARENTWIN ]
zcurses delwin TARGETWIN
zcurses refresh [ TARGETWIN ... ]
zcurses touch TARGETWIN ...
zcurses move TARGETWIN NEW_Y NEW_X
zcurses clear TARGETWIN [ redraw | eol | bot ]
zcurses position TARGETWIN ARRAY
zcurses char TARGETWIN CHARACTER
zcurses string TARGETWIN STRING
zcurses border TARGETWIN BORDER
zcurses attr TARGETWIN [ [+|-]ATTRIBUTE | FG_COL/BG_COL ] [...]
zcurses bg TARGETWIN [ [+|-]ATTRIBUTE | FG_COL/BG_COL | @CHAR ] [...]
zcurses scroll TARGETWIN [ on | off | [+|-]LINES ]
zcurses input TARGETWIN [ PARAM [ KPARAM [ MPARAM ] ] ]
zcurses mouse [ delay NUM | [+|-]motion ]
zcurses timeout TARGETWIN INTVAL
zcurses querychar TARGETWIN [ PARAM ]
zcurses resize HEIGHT WIDTH [ endwin | nosave | endwin_nosave ]
     Manipulate curses windows.  All uses of this command should be
     bracketed by `zcurses init' to initialise use of curses, and
     `zcurses end' to end it; omitting `zcurses end' can cause the
     terminal to be in an unwanted state.

     The subcommand addwin creates a window with NLINES lines and NCOLS
     columns.  Its upper left corner will be placed at row BEGIN_Y and
     column BEGIN_X of the screen.  TARGETWIN is a string and refers to
     the name of a window that is not currently assigned.  Note in
     particular the curses convention that vertical values appear
     before horizontal values.

     If addwin is given an existing window as the final argument, the
     new window is created as a subwindow of PARENTWIN.  This differs
     from an ordinary new window in that the memory of the window
     contents is shared with the parent's memory.  Subwindows must be
     deleted before their parent.  Note that the coordinates of
     subwindows are relative to the screen, not the parent, as with
     other windows.

     Use the subcommand delwin to delete a window created with addwin.
     Note that end does _not_ implicitly delete windows, and that
     delwin does not erase the screen image of the window.

     The window corresponding to the full visible screen is called
     stdscr; it always exists after `zcurses init' and cannot be delete
     with delwin.

     The subcommand refresh will refresh window TARGETWIN; this is
     necessary to make any pending changes (such as characters you have
     prepared for output with char) visible on the screen.  refresh
     without an argument causes the screen to be cleared and redrawn.
     If multiple windows are given, the screen is updated once at the
     end.

     The subcommand touch marks the TARGETWINs listed as changed.  This
     is necessary before refreshing windows if a window that was in
     front of another window (which may be stdscr) is deleted.

     The subcommand move moves the cursor position in TARGETWIN to new
     coordinates NEW_Y and NEW_X.  Note that the subcommand string (but
     not the subcommand char) advances the cursor position over the
     characters added.

     The subcommand clear erases the contents of TARGETWIN.  One (and
     no more than one) of three options may be specified.  With the
     option redraw, in addition the next refresh of TARGETWIN will
     cause the screen to be cleared and repainted.  With the option
     eol, TARGETWIN is only cleared to the end of the current cursor
     line.  With the option bot, TARGETWIN is cleared to the end of the
     window, i.e everything to the right and below the cursor is
     cleared.

     The subcommand position writes various positions associated with
     TARGETWIN into the array named ARRAY.  These are, in order:
    -
          The y and x coordinates of the cursor relative to the top left
          of TARGETWIN

    -
          The y and x coordinates of the top left of TARGETWIN on the
          screen

    -
          The size of TARGETWIN in y and x dimensions.

     Outputting characters and strings are achieved by char and string
     respectively.

     To draw a border around window TARGETWIN, use border.  Note that
     the border is not subsequently handled specially:  in other words,
     the border is simply a set of characters output at the edge of the
     window.  Hence it can be overwritten, can scroll off the window,
     etc.

     The subcommand attr will set TARGETWIN's attributes or
     foreground/background color pair for any successive character
     output.  Each ATTRIBUTE given on the line may be prepended by a +
     to set or a - to unset that attribute; + is assumed if absent.  The
     attributes supported are blink, bold, dim, reverse, standout, and
     underline.

     Each FG_COL/BG_COL attribute (to be read as `FG_COL on BG_COL')
     sets the foreground and background color for character output.
     The color default is sometimes available (in particular if the
     library is ncurses), specifying the foreground or background color
     with which the terminal started.  The color pair default/default
     is always available. To use more than the 8 named colors (red,
     green, etc.) construct the FG_COL/BG_COL pairs where FG_COL and
     BG_COL are decimal integers, e.g 128/200.  The maximum color value
     is 254 if the terminal supports 256 colors.

     bg overrides the color and other attributes of all characters in
     the window.  Its usual use is to set the background initially, but
     it will overwrite the attributes of any characters at the time
     when it is called.  In addition to the arguments allowed with
     attr, an argument @CHAR specifies a character to be shown in
     otherwise blank areas of the window.  Owing to limitations of
     curses this cannot be a multibyte character (use of ASCII
     characters only is recommended).  As the specified set of
     attributes override the existing background, turning attributes
     off in the arguments is not useful, though this does not cause an
     error.

     The subcommand scroll can be used with on or off to enabled or
     disable scrolling of a window when the cursor would otherwise move
     below the window due to typing or output.  It can also be used
     with a positive or negative integer to scroll the window up or
     down the given number of lines without changing the current cursor
     position (which therefore appears to move in the opposite
     direction relative to the window).  In the second case, if
     scrolling is off it is temporarily turned on to allow the window
     to be scrolled.

     The subcommand input reads a single character from the window
     without echoing it back.  If PARAM is supplied the character is
     assigned to the parameter PARAM, else it is assigned to the
     parameter REPLY.

     If both PARAM and KPARAM are supplied, the key is read in `keypad'
     mode.  In this mode special keys such as function keys and arrow
     keys return the name of the key in the parameter KPARAM.  The key
     names are the macros defined in the curses.h or ncurses.h with the
     prefix `KEY_' removed; see also the description of the parameter
     zcurses_keycodes below.  Other keys cause a value to be set in
     PARAM as before.  On a successful return only one of PARAM or
     KPARAM contains a non-empty string; the other is set to an empty
     string.

     If MPARAM is also supplied, input attempts to handle mouse input.
     This is only available with the ncurses library; mouse handling
     can be detected by checking for the exit status of `zcurses mouse'
     with no arguments.  If a mouse button is clicked (or double- or
     triple-clicked, or pressed or released with a configurable delay
     from being clicked) then kparam is set to the string MOUSE, and
     MPARAM is set to an array consisting of the following elements:
    -
          An identifier to discriminate different input devices; this
          is only rarely useful.

    -
          The x, y and z coordinates of the mouse click relative to the
          full screen, as three elements in that order (i.e. the y
          coordinate is, unusually, after the x coordinate).  The z
          coordinate is only available for a few unusual input devices
          and is otherwise set to zero.

    -
          Any events that occurred as separate items; usually there
          will be just one.  An event consists of PRESSED, RELEASED,
          CLICKED, DOUBLE_CLICKED or TRIPLE_CLICKED followed
          immediately (in the same element) by the number of the button.

    -
          If the shift key was pressed, the string SHIFT.

    -
          If the control key was pressed, the string CTRL.

    -
          If the alt key was pressed, the string ALT.

     Not all mouse events may be passed through to the terminal window;
     most terminal emulators handle some mouse events themselves.  Note
     that the ncurses manual implies that using input both with and
     without mouse handling may cause the mouse cursor to appear and
     disappear.

     The subcommand mouse can be used to configure the use of the mouse.
     There is no window argument; mouse options are global.  `zcurses
     mouse' with no arguments returns status 0 if mouse handling is
     possible, else status 1.  Otherwise, the possible arguments (which
     may be combined on the same command line) are as follows.  delay
     NUM sets the maximum delay in milliseconds between press and
     release events to be considered as a click; the value 0 disables
     click resolution, and the default is one sixth of a second.
     motion proceeded by an optional `+' (the default) or - turns on or
     off reporting of mouse motion in addition to clicks, presses and
     releases, which are always reported.  However, it appears reports
     for mouse motion are not currently implemented.

     The subcommand timeout specifies a timeout value for input from
     TARGETWIN.  If INTVAL is negative, `zcurses input' waits
     indefinitely for a character to be typed; this is the default.  If
     INTVAL is zero, `zcurses input' returns immediately; if there is
     typeahead it is returned, else no input is done and status 1 is
     returned.  If INTVAL is positive, `zcurses input' waits INTVAL
     milliseconds for input and if there is none at the end of that
     period returns status 1.

     The subcommand querychar queries the character at the current
     cursor position.  The return values are stored in the array named
     PARAM if supplied, else in the array reply.  The first value is
     the character (which may be a multibyte character if the system
     supports them); the second is the color pair in the usual
     FG_COL/BG_COL notation, or 0 if color is not supported.  Any
     attributes other than color that apply to the character, as set
     with the subcommand attr, appear as additional elements.

     The subcommand resize resizes stdscr and all windows to given
     dimensions (windows that stick out from the new dimensions are
     resized down). The underlying curses extension (resize_term call)
     can be unavailable. To verify, zeroes can be used for HEIGHT and
     WIDTH. If the result of the subcommand is 0, resize_term is
     available (2 otherwise). Tests show that resizing can be normally
     accomplished by calling zcurses end and zcurses refresh. The
     resize subcommand is provided for versatility. Multiple system
     configurations have been checked and zcurses end and zcurses
     refresh are still needed for correct terminal state after resize.
     To invoke them with resize, use ENDWIN argument.  Using NOSAVE
     argument will cause new terminal state to not be saved internally
     by zcurses. This is also provided for versatility and should
     normally be not needed.



22.9.2 Parameters
-----------------


ZCURSES_COLORS
     Readonly integer.  The maximum number of colors the terminal
     supports.  This value is initialised by the curses library and is
     not available until the first time zcurses init is run.

ZCURSES_COLOR_PAIRS
     Readonly integer.  The maximum number of color pairs FG_COL/BG_COL
     that may be defined in `zcurses attr' commands; note this limit
     applies to all color pairs that have been used whether or not they
     are currently active.  This value is initialised by the curses
     library and is not available until the first time zcurses init is
     run.

zcurses_attrs
     Readonly array.  The attributes supported by zsh/curses; available
     as soon as the module is loaded.

zcurses_colors
     Readonly array.  The colors supported by zsh/curses; available as
     soon as the module is loaded.

zcurses_keycodes
     Readonly array.  The values that may be returned in the second
     parameter supplied to `zcurses input' in the order in which they
     are defined internally by curses.  Not all function keys are
     listed, only F0; curses reserves space for F0 up to F63.

zcurses_windows
     Readonly array.  The current list of windows, i.e. all windows that
     have been created with `zcurses addwin' and not removed with
     `zcurses delwin'.



File: zsh.info,  Node: The zsh/datetime Module,  Next: The zsh/db/gdbm Module,  Prev: The zsh/curses Module,  Up: Zsh Modules

22.10 The zsh/datetime Module
=============================



   The zsh/datetime module makes available one builtin command:


strftime [ -s SCALAR ] FORMAT [ EPOCHTIME [ NANOSECONDS ] ]
strftime -r [ -q ] [ -s SCALAR ] FORMAT TIMESTRING
     Output the date in the FORMAT specified.  With no EPOCHTIME, the
     current system date/time is used; optionally, EPOCHTIME may be
     used to specify the number of seconds since the epoch, and
     NANOSECONDS may additionally be used to specify the number of
     nanoseconds past the second (otherwise that number is assumed to
     be 0).  See man page strftime(3) for details.  The zsh extensions
     described in *Note Prompt Expansion:: are also available.


    -q
          Run quietly; suppress printing of all error messages
          described below.  Errors for invalid EPOCHTIME values are
          always printed.

    -r
          With the option -r (reverse), use FORMAT to parse the input
          string TIMESTRING and output the number of seconds since the
          epoch at which the time occurred.  The parsing is implemented
          by the system function strptime; see man page strptime(3).
          This means that zsh format extensions are not available, but
          for reverse lookup they are not required.

          In most implementations of strftime any timezone in the
          TIMESTRING is ignored and the local timezone declared by the
          TZ environment variable is used; other parameters are set to
          zero if not present.

          If TIMESTRING does not match FORMAT the command returns
          status 1 and prints an error message.  If TIMESTRING matches
          FORMAT but not all characters in TIMESTRING were used, the
          conversion succeeds but also prints an error message.

          If either of the system functions strptime or mktime is not
          available, status 2 is returned and an error message is
          printed.

    -s SCALAR
          Assign the date string (or epoch time in seconds if -r is
          given) to SCALAR instead of printing it.


     Note that depending on the system's declared integral time type,
     strftime may produce incorrect results for epoch times greater than
     2147483647 which corresponds to 2038-01-19 03:14:07 +0000.


The zsh/datetime module makes available several parameters; all are
readonly:


EPOCHREALTIME
     A floating point value representing the number of seconds since
     the epoch.  The notional accuracy is to nanoseconds if the
     clock_gettime call is available and to microseconds otherwise, but
     in practice the range of double precision floating point and shell
     scheduling latencies may be significant effects.

EPOCHSECONDS
     An integer value representing the number of seconds since the
     epoch.

epochtime
     An array value containing the number of seconds since the epoch in
     the first element and the remainder of the time since the epoch in
     nanoseconds in the second element.  To ensure the two elements are
     consistent the array should be copied or otherwise referenced as a
     single substitution before the values are used.  The following
     idiom may be used:


          for secs nsecs in $epochtime; do
            ...
          done




File: zsh.info,  Node: The zsh/db/gdbm Module,  Next: The zsh/deltochar Module,  Prev: The zsh/datetime Module,  Up: Zsh Modules

22.11 The zsh/db/gdbm Module
============================



   The zsh/db/gdbm module is used to create "tied" associative arrays
that interface to database files.  If the GDBM interface is not
available, the builtins defined by this module will report an error.
This module is also intended as a prototype for creating additional
database interfaces, so the ztie builtin may move to a more generic
module in the future.

The builtins in this module are:


ztie -d db/gdbm -f FILENAME [ -r ] ARRAYNAME
     Open the GDBM database identified by FILENAME and, if successful,
     create the associative array ARRAYNAME linked to the file.  To
     create a local tied array, the parameter must first be declared,
     so commands similar to the following would be executed inside a
     function scope:


          local -A sampledb
          ztie -d db/gdbm -f sample.gdbm sampledb

     The -r option opens the database file for reading only, creating a
     parameter with the readonly attribute.  Without this option, using
     `ztie' on a file for which the user does not have write permission
     is an error.  If writable, the database is opened synchronously so
     fields changed in ARRAYNAME are immediately written to FILENAME.

     Changes to the file modes FILENAME after it has been opened do not
     alter the state of ARRAYNAME, but `typeset -r ARRAYNAME' works as
     expected.

zuntie [ -u ] ARRAYNAME ...
     Close the GDBM database associated with each ARRAYNAME and then
     unset the parameter.  The -u option forces an unset of parameters
     made readonly with `ztie -r'.

     This happens automatically if the parameter is explicitly unset or
     its local scope (function) ends.  Note that a readonly parameter
     may not be explicitly unset, so the only way to unset a global
     parameter created with `ztie -r' is to use `zuntie -u'.

zgdbmpath PARAMETERNAME
     Put path to database file assigned to PARAMETERNAME into REPLY
     scalar.

zgdbm_tied
     Array holding names of all tied parameters.


The fields of an associative array tied to GDBM are neither cached nor
otherwise stored in memory, they are read from or written to the
database on each reference.  Thus, for example, the values in a
readonly array may be changed by a second writer of the same database
file.


File: zsh.info,  Node: The zsh/deltochar Module,  Next: The zsh/example Module,  Prev: The zsh/db/gdbm Module,  Up: Zsh Modules

22.12 The zsh/deltochar Module
==============================



   The zsh/deltochar module makes available two ZLE functions:


delete-to-char
     Read a character from the keyboard, and delete from the cursor
     position up to and including the next (or, with repeat count N,
     the Nth) instance of that character.  Negative repeat counts mean
     delete backwards.

zap-to-char
     This behaves like delete-to-char, except that the final occurrence
     of the character itself is not deleted.



File: zsh.info,  Node: The zsh/example Module,  Next: The zsh/files Module,  Prev: The zsh/deltochar Module,  Up: Zsh Modules

22.13 The zsh/example Module
============================



   The zsh/example module makes available one builtin command:


example [ -flags ] [ ARGS ... ]
     Displays the flags and arguments it is invoked with.


The purpose of the module is to serve as an example of how to write a
module.


File: zsh.info,  Node: The zsh/files Module,  Next: The zsh/langinfo Module,  Prev: The zsh/example Module,  Up: Zsh Modules

22.14 The zsh/files Module
==========================



   The zsh/files module makes available some common commands for file
manipulation as builtins; these commands are probably not needed for
many normal situations but can be useful in emergency recovery
situations with constrained resources.  The commands do not implement
all features now required by relevant standards committees.

For all commands, a variant beginning zf_ is also available and loaded
automatically.  Using the features capability of zmodload will let you
load only those names you want.  Note that it's possible to load only
the builtins with zsh-specific names using the following command:


     zmodload -m -F zsh/files b:zf_\*

The commands loaded by default are:


chgrp [ -hRs ] GROUP FILENAME ...
     Changes group of files specified.  This is equivalent to chown with
     a USER-SPEC argument of `:GROUP'.

chmod [ -Rs ] MODE FILENAME ...
     Changes mode of files specified.

     The specified MODE must be in octal.

     The -R option causes chmod to recursively descend into directories,
     changing the mode of all files in the directory after changing the
     mode of the directory itself.

     The -s option is a zsh extension to chmod functionality.  It
     enables paranoid behaviour, intended to avoid security problems
     involving a chmod being tricked into affecting files other than
     the ones intended.  It will refuse to follow symbolic links, so
     that (for example) ``chmod 600 /tmp/foo/passwd'' can't
     accidentally chmod /etc/passwd if /tmp/foo happens to be a link to
     /etc.  It will also check where it is after leaving directories,
     so that a recursive chmod of a deep directory tree can't end up
     recursively chmoding /usr as a result of directories being moved
     up the tree.

chown [ -hRs ] USER-SPEC FILENAME ...
     Changes ownership and group of files specified.

     The USER-SPEC can be in four forms:


    USER
          change owner to USER; do not change group

    USER::
          change owner to USER; do not change group

    USER:
          change owner to USER; change group to USER's primary group

    USER:GROUP
          change owner to USER; change group to GROUP

    :GROUP
          do not change owner; change group to GROUP

     In each case, the `:' may instead be a `.'.  The rule is that if
     there is a `:' then the separator is `:', otherwise if there is a
     `.' then the separator is `.', otherwise there is no separator.

     Each of USER and GROUP may be either a username (or group name, as
     appropriate) or a decimal user ID (group ID).  Interpretation as a
     name takes precedence, if there is an all-numeric username (or
     group name).

     If the target is a symbolic link, the -h option causes chown to set
     the ownership of the link instead of its target.

     The -R option causes chown to recursively descend into directories,
     changing the ownership of all files in the directory after
     changing the ownership of the directory itself.

     The -s option is a zsh extension to chown functionality.  It
     enables paranoid behaviour, intended to avoid security problems
     involving a chown being tricked into affecting files other than
     the ones intended.  It will refuse to follow symbolic links, so
     that (for example) ``chown luser /tmp/foo/passwd'' can't
     accidentally chown /etc/passwd if /tmp/foo happens to be a link to
     /etc.  It will also check where it is after leaving directories,
     so that a recursive chown of a deep directory tree can't end up
     recursively chowning /usr as a result of directories being moved
     up the tree.

ln [ -dfhins ] FILENAME DEST
ln [ -dfhins ] FILENAME ... DIR
     Creates hard (or, with -s, symbolic) links.  In the first form, the
     specified DESTination is created, as a link to the specified
     FILENAME.  In the second form, each of the FILENAMEs is taken in
     turn, and linked to a pathname in the specified DIRectory that has
     the same last pathname component.

     Normally, ln will not attempt to create hard links to directories.
     This check can be overridden using the -d option.  Typically only
     the super-user can actually succeed in creating hard links to
     directories.  This does not apply to symbolic links in any case.

     By default, existing files cannot be replaced by links.  The -i
     option causes the user to be queried about replacing existing
     files.  The -f option causes existing files to be silently
     deleted, without querying.  -f takes precedence.

     The -h and -n options are identical and both exist for
     compatibility; either one indicates that if the target is a symlink
     then it should not be dereferenced.  Typically this is used in
     combination with -sf so that if an existing link points to a
     directory then it will be removed, instead of followed.  If this
     option is used with multiple filenames and the target is a
     symbolic link pointing to a directory then the result is an error.

mkdir [ -p ] [ -m MODE ] DIR ...
     Creates directories.  With the -p option, non-existing parent
     directories are first created if necessary, and there will be no
     complaint if the directory already exists.  The -m option can be
     used to specify (in octal) a set of file permissions for the
     created directories, otherwise mode 777 modified by the current
     umask (see man page umask(2)) is used.

mv [ -fi ] FILENAME DEST
mv [ -fi ] FILENAME ... DIR
     Moves files.  In the first form, the specified FILENAME is moved
     to the specified DESTination.  In the second form, each of the
     FILENAMEs is taken in turn, and moved to a pathname in the
     specified DIRectory that has the same last pathname component.

     By default, the user will be queried before replacing any file
     that the user cannot write to, but writable files will be silently
     removed.  The -i option causes the user to be queried about
     replacing any existing files.  The -f option causes any existing
     files to be silently deleted, without querying.  -f takes
     precedence.

     Note that this mv will not move files across devices.  Historical
     versions of mv, when actual renaming is impossible, fall back on
     copying and removing files; if this behaviour is desired, use cp
     and rm manually.  This may change in a future version.

rm [ -dfiRrs ] FILENAME ...
     Removes files and directories specified.

     Normally, rm will not remove directories (except with the -R or -r
     options).  The -d option causes rm to try removing directories
     with unlink (see man page unlink(2)), the same method used for
     files.  Typically only the super-user can actually succeed in
     unlinking directories in this way.  -d takes precedence over -R
     and -r.

     By default, the user will be queried before removing any file that
     the user cannot write to, but writable files will be silently
     removed.  The -i option causes the user to be queried about
     removing any files.  The -f option causes files to be silently
     deleted, without querying, and suppresses all error indications.
     -f takes precedence.

     The -R and -r options cause rm to recursively descend into
     directories, deleting all files in the directory before removing
     the directory with the rmdir system call (see man page rmdir(2)).

     The -s option is a zsh extension to rm functionality.  It enables
     paranoid behaviour, intended to avoid common security problems
     involving a root-run rm being tricked into removing files other
     than the ones intended.  It will refuse to follow symbolic links,
     so that (for example) ``rm /tmp/foo/passwd'' can't accidentally
     remove /etc/passwd if /tmp/foo happens to be a link to /etc.  It
     will also check where it is after leaving directories, so that a
     recursive removal of a deep directory tree can't end up
     recursively removing /usr as a result of directories being moved
     up the tree.

rmdir DIR ...
     Removes empty directories specified.

sync
     Calls the system call of the same name (see man page sync(2)),
     which flushes dirty buffers to disk.  It might return before the
     I/O has actually been completed.



File: zsh.info,  Node: The zsh/langinfo Module,  Next: The zsh/mapfile Module,  Prev: The zsh/files Module,  Up: Zsh Modules

22.15 The zsh/langinfo Module
=============================



   The zsh/langinfo module makes available one parameter:


langinfo
     An associative array that maps langinfo elements to their values.

     Your implementation may support a number of the following keys:

     CODESET, D_T_FMT, D_FMT, T_FMT, RADIXCHAR, THOUSEP, YESEXPR,
     NOEXPR, CRNCYSTR, ABDAY_{1..7}, DAY_{1..7}, ABMON_{1..12},
     MON_{1..12}, T_FMT_AMPM, AM_STR, PM_STR, ERA, ERA_D_FMT,
     ERA_D_T_FMT, ERA_T_FMT, ALT_DIGITS




File: zsh.info,  Node: The zsh/mapfile Module,  Next: The zsh/mathfunc Module,  Prev: The zsh/langinfo Module,  Up: Zsh Modules

22.16 The zsh/mapfile Module
============================



   The zsh/mapfile module provides one special associative array
parameter of the same name.


mapfile
     This associative array takes as keys the names of files; the
     resulting value is the content of the file.  The value is treated
     identically to any other text coming from a parameter.  The value
     may also be assigned to, in which case the file in question is
     written (whether or not it originally existed); or an element may
     be unset, which will delete the file in question.  For example,
     `vared mapfile[myfile]' works as expected, editing the file
     `myfile'.

     When the array is accessed as a whole, the keys are the names of
     files in the current directory, and the values are empty (to save
     a huge overhead in memory).  Thus ${(k)mapfile} has the same
     effect as the glob operator *(D), since files beginning with a dot
     are not special.  Care must be taken with expressions such as rm
     ${(k)mapfile}, which will delete every file in the current
     directory without the usual `rm *' test.

     The parameter mapfile may be made read-only; in that case, files
     referenced may not be written or deleted.

     A file may conveniently be read into an array as one line per
     element with the form `ARRAY=("${(f@)mapfile[FILENAME]}")'.  The
     double quotes and the `@' are necessary to prevent empty lines
     from being removed.  Note that if the file ends with a newline,
     the shell will split on the final newline, generating an additional
     empty field; this can be suppressed by using
     `ARRAY=("${(f@)${mapfile[FILENAME]%$'\n'}}")'.



22.16.1 Limitations
-------------------

Although reading and writing of the file in question is efficiently
handled, zsh's internal memory management may be arbitrarily baroque;
however, mapfile is usually very much more efficient than anything
involving a loop.  Note in particular that the whole contents of the
file will always reside physically in memory when accessed (possibly
multiple times, due to standard parameter substitution operations).  In
particular, this means handling of sufficiently long files (greater
than the machine's swap space, or than the range of the pointer type)
will be incorrect.

No errors are printed or flagged for non-existent, unreadable, or
unwritable files, as the parameter mechanism is too low in the shell
execution hierarchy to make this convenient.

It is unfortunate that the mechanism for loading modules does not yet
allow the user to specify the name of the shell parameter to be given
the special behaviour.


File: zsh.info,  Node: The zsh/mathfunc Module,  Next: The zsh/nearcolor Module,  Prev: The zsh/mapfile Module,  Up: Zsh Modules

22.17 The zsh/mathfunc Module
=============================



   The zsh/mathfunc module provides standard mathematical functions for
use when evaluating mathematical formulae.  The syntax agrees with
normal C and FORTRAN conventions, for example,


     (( f = sin(0.3) ))

assigns the sine of 0.3 to the parameter f.

Most functions take floating point arguments and return a floating point
value.  However, any necessary conversions from or to integer type will
be performed automatically by the shell.  Apart from atan with a second
argument and the abs, int and float functions, all functions behave as
noted in the manual page for the corresponding C function, except that
any arguments out of range for the function in question will be
detected by the shell and an error reported.

The following functions take a single floating point argument: acos,
acosh, asin, asinh, atan, atanh, cbrt, ceil, cos, cosh, erf, erfc, exp,
expm1, fabs, floor, gamma, j0, j1, lgamma, log, log10, log1p, log2,
logb, sin, sinh, sqrt, tan, tanh, y0, y1.  The atan function can
optionally take a second argument, in which case it behaves like the C
function atan2.  The ilogb function takes a single floating point
argument, but returns an integer.

The function signgam takes no arguments, and returns an integer, which
is the C variable of the same name, as described in man page gamma(3).
Note that it is therefore only useful immediately after a call to gamma
or lgamma.  Note also that `signgam()' and `signgam' are distinct
expressions.

The functions min, max, and sum are defined not in this module but in
the zmathfunc autoloadable function, described in *Note Mathematical
Functions::.

The following functions take two floating point arguments: copysign,
fmod, hypot, nextafter.

The following take an integer first argument and a floating point second
argument: jn, yn.

The following take a floating point first argument and an integer second
argument: ldexp, scalb.

The function abs does not convert the type of its single argument; it
returns the absolute value of either a floating point number or an
integer.  The functions float and int convert their arguments into a
floating point or integer value (by truncation) respectively.

Note that the C pow function is available in ordinary math evaluation
as the `**' operator and is not provided here.

The function rand48 is available if your system's mathematical library
has the function erand48(3).  It returns a pseudo-random floating point
number between 0 and 1.  It takes a single string optional argument.

If the argument is not present, the random number seed is initialised by
three calls to the rand(3) function -- this produces the same random
numbers as the next three values of $RANDOM.

If the argument is present, it gives the name of a scalar parameter
where the current random number seed will be stored.  On the first
call, the value must contain at least twelve hexadecimal digits (the
remainder of the string is ignored), or the seed will be initialised in
the same manner as for a call to rand48 with no argument.  Subsequent
calls to rand48(PARAM) will then maintain the seed in the parameter
PARAM as a string of twelve hexadecimal digits, with no base signifier.
The random number sequences for different parameters are completely
independent, and are also independent from that used by calls to rand48
with no argument.

For example, consider


     print $(( rand48(seed) ))
     print $(( rand48() ))
     print $(( rand48(seed) ))

Assuming $seed does not exist, it will be initialised by the first
call.  In the second call, the default seed is initialised; note,
however, that because of the properties of rand() there is a
correlation between the seeds used for the two initialisations, so for
more secure uses, you should generate your own 12-byte seed.  The third
call returns to the same sequence of random numbers used in the first
call, unaffected by the intervening rand48().


File: zsh.info,  Node: The zsh/nearcolor Module,  Next: The zsh/newuser Module,  Prev: The zsh/mathfunc Module,  Up: Zsh Modules

22.18 The zsh/nearcolor Module
==============================



   The zsh/nearcolor module replaces colours specified as hex triplets
with the nearest colour in the 88 or 256 colour palettes that are widely
used by terminal emulators.  By default, 24-bit true colour escape codes
are generated when colours are specified using hex triplets.  These are
not supported by all terminals.  The purpose of this module is to make
it easier to define colour preferences in a form that can work across a
range of terminal emulators.

Aside from the default colour, the ANSI standard for terminal escape
codes provides for eight colours. The bright attribute brings this to
sixteen. These basic colours are commonly used in terminal applications
due to being widely supported. Expanded 88 and 256 colour palettes are
also common and, while the first sixteen colours vary somewhat between
terminals and configurations, these add a generally consistent and
predictable set of colours.

In order to use the zsh/nearcolor module, it only needs to be loaded.
Thereafter, whenever a colour is specified using a hex triplet, it will
be compared against each of the available colours and the closest will
be selected. The first sixteen colours are never matched in this
process due to being unpredictable.

It isn't possible to reliably detect support for true colour in the
terminal emulator. It is therefore recommended to be selective in
loading the zsh/nearcolor module. For example, the following checks the
COLORTERM environment variable:


     [[ $COLORTERM = *(24bit|truecolor)* ]] || zmodload zsh/nearcolor

Note that some terminals accept the true color escape codes but map
them internally to a more limited palette in a similar manner to the
zsh/nearcolor module.


File: zsh.info,  Node: The zsh/newuser Module,  Next: The zsh/parameter Module,  Prev: The zsh/nearcolor Module,  Up: Zsh Modules

22.19 The zsh/newuser Module
============================



   The zsh/newuser module is loaded at boot if it is available, the RCS
option is set, and the PRIVILEGED option is not set (all three are true
by default).  This takes place immediately after commands in the global
zshenv file (typically /etc/zshenv), if any, have been executed.  If
the module is not available it is silently ignored by the shell; the
module may safely be removed from $MODULE_PATH by the administrator if
it is not required.

On loading, the module tests if any of the start-up files .zshenv,
.zprofile, .zshrc or .zlogin exist in the directory given by the
environment variable ZDOTDIR, or the user's home directory if that is
not set.  The test is not performed and the module halts processing if
the shell was in an emulation mode (i.e. had been invoked as some other
shell than zsh).

If none of the start-up files were found, the module then looks for the
file newuser first in a sitewide directory, usually the parent
directory of the site-functions directory, and if that is not found the
module searches in a version-specific directory, usually the parent of
the functions directory containing version-specific functions.  (These
directories can be configured when zsh is built using the
-enable-site-scriptdir=DIR and -enable-scriptdir=DIR flags to
configure, respectively; the defaults are PREFIX/share/zsh and
PREFIX/share/zsh/$ZSH_VERSION where the default PREFIX is /usr/local.)

If the file newuser is found, it is then sourced in the same manner as
a start-up file.  The file is expected to contain code to install
start-up files for the user, however any valid shell code will be
executed.

The zsh/newuser module is then unconditionally unloaded.

Note that it is possible to achieve exactly the same effect as the
zsh/newuser module by adding code to /etc/zshenv.  The module exists
simply to allow the shell to make arrangements for new users without
the need for intervention by package maintainers and system
administrators.

The script supplied with the module invokes the shell function
zsh-newuser-install.  This may be invoked directly by the user even if
the zsh/newuser module is disabled.  Note, however, that if the module
is not installed the function will not be installed either.  The
function is documented in *Note User Configuration Functions::.


File: zsh.info,  Node: The zsh/parameter Module,  Next: The zsh/pcre Module,  Prev: The zsh/newuser Module,  Up: Zsh Modules

22.20 The zsh/parameter Module
==============================



   The zsh/parameter module gives access to some of the internal hash
tables used by the shell by defining some special parameters.


options
     The keys for this associative array are the names of the options
     that can be set and unset using the setopt and unsetopt builtins.
     The value of each key is either the string on if the option is
     currently set, or the string off if the option is unset.  Setting
     a key to one of these strings is like setting or unsetting the
     option, respectively. Unsetting a key in this array is like
     setting it to the value off.

commands
     This array gives access to the command hash table. The keys are the
     names of external commands, the values are the pathnames of the
     files that would be executed when the command would be invoked.
     Setting a key in this array defines a new entry in this table in
     the same way as with the hash builtin. Unsetting a key as in `unset
     "commands[foo]"' removes the entry for the given key from the
     command hash table.

functions
     This associative array maps names of enabled functions to their
     definitions. Setting a key in it is like defining a function with
     the name given by the key and the body given by the value.
     Unsetting a key removes the definition for the function named by
     the key.

dis_functions
     Like functions but for disabled functions.

functions_source
     This readonly associative array maps names of enabled functions to
     the name of the file containing the source of the function.

     For an autoloaded function that has already been loaded, or marked
     for autoload with an absolute path, or that has had its path
     resolved with `functions -r', this is the file found for
     autoloading, resolved to an absolute path.

     For a function defined within the body of a script or sourced file,
     this is the name of that file.  In this case, this is the exact
     path originally used to that file, which may be a relative path.

     For any other function, including any defined at an interactive
     prompt or an autoload function whose path has not yet been
     resolved, this is the empty string.  However, the hash element is
     reported as defined just so long as the function is present:  the
     keys to this hash are the same as those to $functions.

dis_functions_source
     Like functions_source but for disabled functions.

builtins
     This associative array gives information about the builtin commands
     currently enabled. The keys are the names of the builtin commands
     and the values are either `undefined' for builtin commands that
     will automatically be loaded from a module if invoked or `defined'
     for builtin commands that are already loaded.

dis_builtins
     Like builtins but for disabled builtin commands.

reswords
     This array contains the enabled reserved words.

dis_reswords
     Like reswords but for disabled reserved words.

patchars
     This array contains the enabled pattern characters.

dis_patchars
     Like patchars but for disabled pattern characters.

aliases
     This maps the names of the regular aliases currently enabled to
     their expansions.

dis_aliases
     Like aliases but for disabled regular aliases.

galiases
     Like aliases, but for global aliases.

dis_galiases
     Like galiases but for disabled global aliases.

saliases
     Like raliases, but for suffix aliases.

dis_saliases
     Like saliases but for disabled suffix aliases.

parameters
     The keys in this associative array are the names of the parameters
     currently defined. The values are strings describing the type of
     the parameter, in the same format used by the t parameter flag, see
     *Note Parameter Expansion:: .  Setting or unsetting keys in this
     array is not possible.

modules
     An associative array giving information about modules. The keys
     are the names of the modules loaded, registered to be autoloaded,
     or aliased. The value says which state the named module is in and
     is one of the strings `loaded', `autoloaded', or `alias:NAME',
     where NAME is the name the module is aliased to.

     Setting or unsetting keys in this array is not possible.

dirstack
     A normal array holding the elements of the directory stack. Note
     that the output of the dirs builtin command includes one more
     directory, the current working directory.

history
     This associative array maps history event numbers to the full
     history lines.  Although it is presented as an associative array,
     the array of all values (${history[@]}) is guaranteed to be
     returned in order from most recent to oldest history event, that
     is, by decreasing history event number.

historywords
     A special array containing the words stored in the history.  These
     also appear in most to least recent order.

jobdirs
     This associative array maps job numbers to the directories from
     which the job was started (which may not be the current directory
     of the job).

     The keys of the associative arrays are usually valid job numbers,
     and these are the values output with, for example, ${(k)jobdirs}.
     Non-numeric job references may be used when looking up a value;
     for example, ${jobdirs[%+]} refers to the current job.

jobtexts
     This associative array maps job numbers to the texts of the
     command lines that were used to start the jobs.

     Handling of the keys of the associative array is as described for
     jobdirs above.

jobstates
     This associative array gives information about the states of the
     jobs currently known. The keys are the job numbers and the values
     are strings of the form `JOB-STATE:MARK:PID=STATE...'. The
     JOB-STATE gives the state the whole job is currently in, one of
     `running', `suspended', or `done'. The MARK is `+' for the current
     job, `-' for the previous job and empty otherwise. This is
     followed by one `:PID=STATE' for every process in the job. The
     PIDs are, of course, the process IDs and the STATE describes the
     state of that process.

     Handling of the keys of the associative array is as described for
     jobdirs above.

nameddirs
     This associative array maps the names of named directories to the
     pathnames they stand for.

userdirs
     This associative array maps user names to the pathnames of their
     home directories.

usergroups
     This associative array maps names of system groups of which the
     current user is a member to the corresponding group identifiers.
     The contents are the same as the groups output by the id command.

funcfiletrace
     This array contains the absolute line numbers and corresponding
     file names for the point where the current function, sourced file,
     or (if EVAL_LINENO is set) eval command was called.  The array is
     of the same length as funcsourcetrace and functrace, but differs
     from funcsourcetrace in that the line and file are the point of
     call, not the point of definition, and differs from functrace in
     that all values are absolute line numbers in files, rather than
     relative to the start of a function, if any.

funcsourcetrace
     This array contains the file names and line numbers of the points
     where the functions, sourced files, and (if EVAL_LINENO is set)
     eval commands currently being executed were defined.  The line
     number is the line where the `function NAME' or `NAME ()' started.
     In the case of an autoloaded function  the line number is
     reported as zero.  The format of each element is FILENAME:LINENO.

     For functions autoloaded from a file in native zsh format, where
     only the body of the function occurs in the file, or for files
     that have been executed by the source or `.' builtins, the trace
     information is shown as FILENAME:0, since the entire file is the
     definition.  The source file name is resolved to an absolute path
     when the function is loaded or the path to it otherwise resolved.

     Most users will be interested in the information in the
     funcfiletrace array instead.

funcstack
     This array contains the names of the functions, sourced files, and
     (if EVAL_LINENO is set) eval commands. currently being executed.
     The first element is the name of the function using the parameter.

     The standard shell array zsh_eval_context can be used to determine
     the type of shell construct being executed at each depth: note,
     however, that is in the opposite order, with the most recent item
     last, and it is more detailed, for example including an entry for
     toplevel, the main shell code being executed either interactively
     or from a script, which is not present in $funcstack.

functrace
     This array contains the names and line numbers of the callers
     corresponding to the functions currently being executed.  The
     format of each element is NAME:LINENO.  Callers are also shown for
     sourced files; the caller is the point where the source or `.'
     command was executed.



File: zsh.info,  Node: The zsh/pcre Module,  Next: The zsh/param/private Module,  Prev: The zsh/parameter Module,  Up: Zsh Modules

22.21 The zsh/pcre Module
=========================



   The zsh/pcre module makes some commands available as builtins:


pcre_compile [ -aimxs ] PCRE
     Compiles a perl-compatible regular expression.

     Option -a will force the pattern to be anchored.  Option -i will
     compile a case-insensitive pattern.  Option -m will compile a
     multi-line pattern; that is, ^ and $ will match newlines within
     the pattern.  Option -x will compile an extended pattern, wherein
     whitespace and # comments are ignored.  Option -s makes the dot
     metacharacter match all characters, including those that indicate
     newline.

pcre_study
     Studies the previously-compiled PCRE which may result in faster
     matching.

pcre_match [ -v VAR ] [ -a ARR ] [ -n OFFSET ] [ -b ] STRING
     Returns successfully if string matches the previously-compiled
     PCRE.

     Upon successful match, if the expression captures substrings
     within parentheses, pcre_match will set the array match to those
     substrings, unless the -a option is given, in which case it will
     set the array ARR.  Similarly, the variable MATCH will be set to
     the entire matched portion of the string, unless the -v option is
     given, in which case the variable VAR will be set.  No variables
     are altered if there is no successful match.  A -n option starts
     searching for a match from the byte OFFSET position in STRING.  If
     the -b option is given, the variable ZPCRE_OP will be set to an
     offset pair string, representing the byte offset positions of the
     entire matched portion within the STRING.  For example, a ZPCRE_OP
     set to "32 45" indicates that the matched portion began on byte
     offset 32 and ended on byte offset 44.  Here, byte offset position
     45 is the position directly after the matched portion.  Keep in
     mind that the byte position isn't necessarily the same as the
     character position when UTF-8 characters are involved.
     Consequently, the byte offset positions are only to be relied on
     in the context of using them for subsequent searches on STRING,
     using an offset position as an argument to the -n option.  This is
     mostly used to implement the "find all non-overlapping matches"
     functionality.

     A simple example of "find all non-overlapping matches":


          string="The following zip codes: 78884 90210 99513"
          pcre_compile -m "\d{5}"
          accum=()
          pcre_match -b -- $string
          while [[ $? -eq 0 ]] do
              b=($=ZPCRE_OP)
              accum+=$MATCH
              pcre_match -b -n $b[2] -- $string
          done
          print -l $accum


The zsh/pcre module makes available the following test condition:


EXPR -pcre-match PCRE
     Matches a string against a perl-compatible regular expression.

     For example,


          [[ "$text" -pcre-match ^d+$ ]] &&
          print text variable contains only "d's".

     If the REMATCH_PCRE option is set, the =~ operator is equivalent to
     -pcre-match, and the NO_CASE_MATCH option may be used.  Note that
     NO_CASE_MATCH never applies to the pcre_match builtin, instead use
     the -i switch of pcre_compile.



File: zsh.info,  Node: The zsh/param/private Module,  Next: The zsh/regex Module,  Prev: The zsh/pcre Module,  Up: Zsh Modules

22.22 The zsh/param/private Module
==================================



   The zsh/param/private module is used to create parameters whose scope
is limited to the current function body, and _not_ to other functions
called by the current function.

This module provides a single autoloaded builtin:

private [ {+|-}AHUahlprtux ] [ {+|-}EFLRZi [ N ] ] [ NAME[=VALUE] ... ]
     The private builtin accepts all the same options and arguments as
     local (*Note Shell Builtin Commands::) except for the `-T' option.
     Tied parameters may not be made private.

     If used at the top level (outside a function scope), private
     creates a normal parameter in the same manner as declare or
     typeset.  A warning about this is printed if WARN_CREATE_GLOBAL is
     set (*Note Options::).  Used inside a function scope, private
     creates a local parameter similar to one declared with local,
     except having special properties noted below.

     Special parameters which expose or manipulate internal shell
     state, such as ARGC, argv, COLUMNS, LINES, UID, EUID, IFS, PROMPT,
     RANDOM, SECONDS, etc., cannot be made private unless the `-h'
     option is used to hide the special meaning of the parameter.  This
     may change in the future.


As with other typeset equivalents, private is both a builtin and a
reserved word, so arrays may be assigned with parenthesized word list
NAME=(VALUE...) syntax.  However, the reserved word `private' is not
available until zsh/param/private is loaded, so care must be taken with
order of execution and parsing for function definitions which use
private.  To compensate for this, the module also adds the option `-P'
to the `local' builtin to declare private parameters.

For example, this construction fails if zsh/param/private has not yet
been loaded when `bad_declaration' is defined:
     bad_declaration() {
       zmodload zsh/param/private
       private array=( one two three )
     }

This construction works because local is already a keyword, and the
module is loaded before the statement is executed:
     good_declaration() {
       zmodload zsh/param/private
       local -P array=( one two three )
     }

The following is usable in scripts but may have trouble with autoload:
     zmodload zsh/param/private
     iffy_declaration() {
       private array=( one two three )
     }

The private builtin may always be used with scalar assignments and for
declarations without assignments.

Parameters declared with private have the following properties:

   * Within the function body where it is declared, the parameter
     behaves as a local, except as noted above for tied or special
     parameters.

   * The type of a parameter declared private cannot be changed in the
     scope where it was declared, even if the parameter is unset.  Thus
     an array cannot be assigned to a private scalar, etc.

   * Within any other function called by the declaring function, the
     private parameter does _NOT_ hide other parameters of the same
     name, so for example a global parameter of the same name is
     visible and may be assigned or unset.  This includes calls to
     anonymous functions, although that may also change in the future.

   * An exported private remains in the environment of inner scopes but
     appears unset for the current shell in those scopes.  Generally,
     exporting private parameters should be avoided.

Note that this differs from the static scope defined by compiled
languages derived from C, in that the a new call to the same function
creates a new scope, i.e., the parameter is still associated with the
call stack rather than with the function definition.  It differs from
ksh `typeset -S' because the syntax used to define the function has no
bearing on whether the parameter scope is respected.


File: zsh.info,  Node: The zsh/regex Module,  Next: The zsh/sched Module,  Prev: The zsh/param/private Module,  Up: Zsh Modules

22.23 The zsh/regex Module
==========================



   The zsh/regex module makes available the following test condition:


EXPR -regex-match REGEX
     Matches a string against a POSIX extended regular expression.  On
     successful match, matched portion of the string will normally be
     placed in the MATCH variable.  If there are any capturing
     parentheses within the regex, then the match array variable will
     contain those.  If the match is not successful, then the variables
     will not be altered.

     For example,


          [[ alphabetical -regex-match ^a([^a]+)a([^a]+)a ]] &&
          print -l $MATCH X $match

     If the option REMATCH_PCRE is not set, then the =~ operator will
     automatically load this module as needed and will invoke the
     -regex-match operator.

     If BASH_REMATCH is set, then the array BASH_REMATCH will be set
     instead of MATCH and match.



File: zsh.info,  Node: The zsh/sched Module,  Next: The zsh/net/socket Module,  Prev: The zsh/regex Module,  Up: Zsh Modules

22.24 The zsh/sched Module
==========================



   The zsh/sched module makes available one builtin command and one
parameter.


sched [-o] [+]HH:MM[:SS] COMMAND ...
sched [-o] [+]SECONDS COMMAND ...
sched [ -ITEM ]
     Make an entry in the scheduled list of commands to execute.  The
     time may be specified in either absolute or relative time, and
     either as hours, minutes and (optionally) seconds separated by a
     colon, or seconds alone.  An absolute number of seconds indicates
     the time since the epoch (1970/01/01 00:00); this is useful in
     combination with the features in the zsh/datetime module, see
     *Note The zsh/datetime Module::.

     With no arguments, prints the list of scheduled commands.  If the
     scheduled command has the -o flag set, this is shown at the start
     of the command.

     With the argument `-ITEM', removes the given item from the list.
     The numbering of the list is continuous and entries are in time
     order, so the numbering can change when entries are added or
     deleted.

     Commands are executed either immediately before a prompt, or while
     the shell's line editor is waiting for input.  In the latter case
     it is useful to be able to produce output that does not interfere
     with the line being edited.  Providing the option -o causes the
     shell to clear the command line before the event and redraw it
     afterwards.  This should be used with any scheduled event that
     produces visible output to the terminal; it is not needed, for
     example, with output that updates a terminal emulator's title bar.

     To effect changes to the editor buffer when an event executes, use
     the `zle' command with no arguments to test whether the editor is
     active, and if it is, then use `zle WIDGET' to access the editor
     via the named WIDGET.

     The sched builtin is not made available by default when the shell
     starts in a mode emulating another shell.  It can be made available
     with the command `zmodload -F zsh/sched b:sched'.



zsh_scheduled_events
     A readonly array corresponding to the events scheduled by the
     sched builtin.  The indices of the array correspond to the numbers
     shown when sched is run with no arguments (provided that the
     KSH_ARRAYS option is not set).  The value of the array consists of
     the scheduled time in seconds since the epoch (see *Note The
     zsh/datetime Module:: for facilities for using this number),
     followed by a colon, followed by any options (which may be empty
     but will be preceded by a `-' otherwise), followed by a colon,
     followed by the command to be executed.

     The sched builtin should be used for manipulating the events.  Note
     that this will have an immediate effect on the contents of the
     array, so that indices may become invalid.



File: zsh.info,  Node: The zsh/net/socket Module,  Next: The zsh/stat Module,  Prev: The zsh/sched Module,  Up: Zsh Modules

22.25 The zsh/net/socket Module
===============================



   The zsh/net/socket module makes available one builtin command:


zsocket [ -altv ] [ -d FD ] [ ARGS ]
     zsocket is implemented as a builtin to allow full use of shell
     command line editing, file I/O, and job control mechanisms.



22.25.1 Outbound Connections
----------------------------




zsocket [ -v ] [ -d FD ] FILENAME
     Open a new Unix domain connection to FILENAME.  The shell
     parameter REPLY will be set to the file descriptor associated with
     that connection.  Currently, only stream connections are supported.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     In order to elicit more verbose output, use -v.

     File descriptors can be closed with normal shell syntax when no
     longer needed, for example:


          exec {REPLY}>&-



22.25.2 Inbound Connections
---------------------------




zsocket -l [ -v ] [ -d FD ] FILENAME
     zsocket -l will open a socket listening on FILENAME.  The shell
     parameter REPLY will be set to the file descriptor associated with
     that listener.  The file descriptor remains open in subshells and
     forked external executables.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     In order to elicit more verbose output, use -v.

zsocket -a [ -tv ] [ -d TARGETFD ] LISTENFD
     zsocket -a will accept an incoming connection to the socket
     associated with LISTENFD.  The shell parameter REPLY will be set
     to the file descriptor associated with the inbound connection.
     The file descriptor remains open in subshells and forked external
     executables.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     If -t is specified, zsocket will return if no incoming connection
     is pending.  Otherwise it will wait for one.

     In order to elicit more verbose output, use -v.



File: zsh.info,  Node: The zsh/stat Module,  Next: The zsh/system Module,  Prev: The zsh/net/socket Module,  Up: Zsh Modules

22.26 The zsh/stat Module
=========================



   The zsh/stat module makes available one builtin command under two
possible names:


zstat [ -gnNolLtTrs ] [ -f FD ] [ -H HASH ] [ -A ARRAY ] [ -F FMT ]
      [ +ELEMENT ] [ FILE ... ]
stat ...
     The command acts as a front end to the stat system call (see man
     page stat(2)).  The same command is provided with two names; as
     the name stat is often used by an external command it is
     recommended that only the zstat form of the command is used.  This
     can be arranged by loading the module with the command `zmodload
     -F zsh/stat b:zstat'.

     If the stat call fails, the appropriate system error message
     printed and status 1 is returned.  The fields of struct stat give
     information about the files provided as arguments to the command.
     In addition to those available from the stat call, an extra
     element `link' is provided.  These elements are:


    device
          The number of the device on which the file resides.

    inode
          The unique number of the file on this device (`_inode_'
          number).

    mode
          The mode of the file; that is, the file's type and access
          permissions.  With the -s option, this will be returned as a
          string corresponding to the first column in the display of
          the ls -l command.

    nlink
          The number of hard links to the file.

    uid
          The user ID of the owner of the file.  With the -s option,
          this is displayed as a user name.

    gid
          The group ID of the file.  With the -s option, this is
          displayed as a group name.

    rdev
          The raw device number.  This is only useful for special
          devices.

    size
          The size of the file in bytes.

    atime
    mtime
    ctime
          The last access, modification and inode change times of the
          file, respectively, as the number of seconds since midnight
          GMT on 1st January, 1970.  With the -s option, these are
          printed as strings for the local time zone; the format can be
          altered with the -F option, and with the -g option the times
          are in GMT.

    blksize
          The number of bytes in one allocation block on the device on
          which the file resides.

    block
          The number of disk blocks used by the file.

    link
          If the file is a link and the -L option is in effect, this
          contains the name of the file linked to, otherwise it is
          empty.  Note that if this element is selected (``zstat
          +link'') then the -L option is automatically used.


     A particular element may be selected by including its name
     preceded by a `+' in the option list; only one element is allowed.
     The element may be shortened to any unique set of leading
     characters.  Otherwise, all elements will be shown for all files.

     Options:


    -A ARRAY
          Instead of displaying the results on standard output, assign
          them to an ARRAY, one struct stat element per array element
          for each file in order.  In this case neither the name of the
          element nor the name of the files appears in ARRAY unless the
          -t or -n options were given, respectively.  If -t is given,
          the element name appears as a prefix to the appropriate array
          element; if -n is given, the file name appears as a separate
          array element preceding all the others.  Other formatting
          options are respected.

    -H HASH
          Similar to -A, but instead assign the values to HASH.  The
          keys are the elements listed above.  If the -n option is
          provided then the name of the file is included in the hash
          with key name.

    -f FD
          Use the file on file descriptor FD instead of named files; no
          list of file names is allowed in this case.

    -F FMT
          Supplies a strftime (see man page strftime(3)) string for the
          formatting of the time elements.  The format string supports
          all of the zsh extensions described in *Note Prompt
          Expansion::.  The -s option is implied.

    -g
          Show the time elements in the GMT time zone.  The -s option
          is implied.

    -l
          List the names of the type elements (to standard output or an
          array as appropriate) and return immediately; arguments, and
          options other than -A, are ignored.

    -L
          Perform an lstat (see man page lstat(2)) rather than a stat
          system call.  In this case, if the file is a link, information
          about the link itself rather than the target file is returned.
          This option is required to make the link element useful.
          It's important to note that this is the exact opposite from
          man page ls(1), etc.

    -n
          Always show the names of files.  Usually these are only shown
          when output is to standard output and there is more than one
          file in the list.

    -N
          Never show the names of files.

    -o
          If a raw file mode is printed, show it in octal, which is
          more useful for human consumption than the default of
          decimal.  A leading zero will be printed in this case.  Note
          that this does not affect whether a raw or formatted file
          mode is shown, which is controlled by the -r and -s options,
          nor whether a mode is shown at all.

    -r
          Print raw data (the default format) alongside string data
          (the -s format); the string data appears in parentheses after
          the raw data.

    -s
          Print mode, uid, gid and the three time elements as strings
          instead of numbers.  In each case the format is like that of
          ls -l.

    -t
          Always show the type names for the elements of struct stat.
          Usually these are only shown when output is to standard
          output and no individual element has been selected.

    -T
          Never show the type names of the struct stat elements.




File: zsh.info,  Node: The zsh/system Module,  Next: The zsh/net/tcp Module,  Prev: The zsh/stat Module,  Up: Zsh Modules

22.27 The zsh/system Module
===========================



   The zsh/system module makes available various builtin commands and
parameters.



22.27.1 Builtins
----------------


syserror [ -e ERRVAR ] [ -p PREFIX ] [ ERRNO | ERRNAME ]
     This command prints out the error message associated with ERRNO, a
     system error number, followed by a newline to standard error.

     Instead of the error number, a name ERRNAME, for example ENOENT,
     may be used.  The set of names is the same as the contents of the
     array errnos, see below.

     If the string PREFIX is given, it is printed in front of the error
     message, with no intervening space.

     If ERRVAR is supplied, the entire message, without a newline, is
     assigned to the parameter names ERRVAR and nothing is output.

     A return status of 0 indicates the message was successfully printed
     (although it may not be useful if the error number was out of the
     system's range), a return status of 1 indicates an error in the
     parameters, and a return status of 2 indicates the error name was
     not recognised (no message is printed for this).

sysopen [ -arw ] [ -m PERMISSIONS ] [ -o OPTIONS ]
        -u FD FILE
     This command opens a file. The -r, -w and -a flags indicate
     whether the file should be opened for reading, writing and
     appending, respectively. The -m option allows the initial
     permissions to use when creating a file to be specified in octal
     form.  The file descriptor is specified with -u. Either an
     explicit file descriptor in the range 0 to 9 can be specified or a
     variable name can be given to which the file descriptor number
     will be assigned.

     The -o option allows various system specific options to be
     specified as a comma-separated list. The following is a list of
     possible options. Note that, depending on the system, some may not
     be available.
    cloexec
          mark file to be closed when other programs are executed (else
          the file descriptor remains open in subshells and forked
          external executables)

    create
    creat
          create file if it does not exist

    excl
          create file, error if it already exists

    noatime
          suppress updating of the file atime

    nofollow
          fail if FILE is a symbolic link

    sync
          request that writes wait until data has been physically
          written

    truncate
    trunc
          truncate file to size 0


     To close the file, use one of the following:


          exec {FD}<&-
          exec {FD}>&-

sysread [ -c COUNTVAR ] [ -i INFD ] [ -o OUTFD ]
        [ -s BUFSIZE ] [ -t TIMEOUT ] [ PARAM ]
     Perform a single system read from file descriptor INFD, or zero if
     that is not given.  The result of the read is stored in PARAM or
     REPLY if that is not given.  If COUNTVAR is given, the number of
     bytes read is assigned to the parameter named by COUNTVAR.

     The maximum number of bytes read is BUFSIZE or 8192 if that is not
     given, however the command returns as soon as any number of bytes
     was successfully read.

     If TIMEOUT is given, it specifies a timeout in seconds, which may
     be zero to poll the file descriptor.  This is handled by the poll
     system call if available, otherwise the select system call if
     available.

     If OUTFD is given, an attempt is made to write all the bytes just
     read to the file descriptor OUTFD.  If this fails, because of a
     system error other than EINTR or because of an internal zsh error
     during an interrupt, the bytes read but not written are stored in
     the parameter named by PARAM if supplied (no default is used in
     this case), and the number of bytes read but not written is stored
     in the parameter named by COUNTVAR if that is supplied.  If it was
     successful, COUNTVAR contains the full number of bytes transferred,
     as usual, and PARAM is not set.

     The error EINTR (interrupted system call) is handled internally so
     that shell interrupts are transparent to the caller.  Any other
     error causes a return.

     The possible return statuses are
    0
          At least one byte of data was successfully read and, if
          appropriate, written.

    1
          There was an error in the parameters to the command.  This is
          the only error for which a message is printed to standard
          error.

    2
          There was an error on the read, or on polling the input file
          descriptor for a timeout.  The parameter ERRNO gives the
          error.

    3
          Data were successfully read, but there was an error writing
          them to OUTFD.  The parameter ERRNO gives the error.

    4
          The attempt to read timed out.  Note this does not set ERRNO
          as this is not a system error.

    5
          No system error occurred, but zero bytes were read.  This
          usually indicates end of file.  The parameters are set
          according to the usual rules; no write to OUTFD is attempted.


sysseek [ -u FD ] [ -w start|end|current ] OFFSET
     The current file position at which future reads and writes will
     take place is adjusted to the specified byte offset. The OFFSET is
     evaluated as a math expression. The -u option allows the file
     descriptor to be specified. By default the offset is specified
     relative to the start or the file but, with the -w option, it is
     possible to specify that the offset should be relative to the
     current position or the end of the file.

syswrite [ -c COUNTVAR ] [ -o OUTFD ] DATA
     The data (a single string of bytes) are written to the file
     descriptor OUTFD, or 1 if that is not given, using the write
     system call.  Multiple write operations may be used if the first
     does not write all the data.

     If COUNTVAR is given, the number of byte written is stored in the
     parameter named by COUNTVAR; this may not be the full length of
     DATA if an error occurred.

     The error EINTR (interrupted system call) is handled internally by
     retrying; otherwise an error causes the command to return.  For
     example, if the file descriptor is set to non-blocking output, an
     error EAGAIN (on some systems, EWOULDBLOCK) may result in the
     command returning early.

     The return status may be 0 for success, 1 for an error in the
     parameters to the command, or 2 for an error on the write; no
     error message is printed in the last case, but the parameter ERRNO
     will reflect the error that occurred.

zsystem flock [ -t TIMEOUT ] [ -f VAR ] [-er] FILE
zsystem flock -u FD_EXPR
     The builtin zsystem's subcommand flock performs advisory file
     locking (via the man page fcntl(2) system call) over the entire
     contents of the given file.  This form of locking requires the
     processes accessing the file to cooperate; its most obvious use is
     between two instances of the shell itself.

     In the first form the named FILE, which must already exist, is
     locked by opening a file descriptor to the file and applying a
     lock to the file descriptor.  The lock terminates when the shell
     process that created the lock exits; it is therefore often
     convenient to create file locks within subshells, since the lock
     is automatically released when the subshell exits.  Note that use
     of the print builtin with the -u option will, as a side effect,
     release the lock, as will redirection to the file in the shell
     holding the lock.  To work around this use a subshell, e.g.
     `(print message) >> FILE'.  Status 0 is returned if the lock
     succeeds, else status 1.

     In the second form the file descriptor given by the arithmetic
     expression FD_EXPR is closed, releasing a lock.  The file
     descriptor can be queried by using the `-f VAR' form during the
     lock; on a successful lock, the shell variable VAR is set to the
     file descriptor used for locking.  The lock will be released if the
     file descriptor is closed by any other means, for example using
     `exec {VAR}>&-'; however, the form described here performs a
     safety check that the file descriptor is in use for file locking.

     By default the shell waits indefinitely for the lock to succeed.
     The option -t TIMEOUT specifies a timeout for the lock in seconds;
     currently this must be an integer.  The shell will attempt to lock
     the file once a second during this period.  If the attempt times
     out, status 2 is returned.

     If the option -e is given, the file descriptor for the lock is
     preserved when the shell uses exec to start a new process;
     otherwise it is closed at that point and the lock released.

     If the option -r is given, the lock is only for reading, otherwise
     it is for reading and writing.  The file descriptor is opened
     accordingly.

zsystem supports SUBCOMMAND
     The builtin zsystem's subcommand supports tests whether a given
     subcommand is supported.  It returns status 0 if so, else status
     1.  It operates silently unless there was a syntax error (i.e. the
     wrong number of arguments), in which case status 255 is returned.
     Status 1 can indicate one of two things:  SUBCOMMAND is known but
     not supported by the current operating system, or SUBCOMMAND is
     not known (possibly because this is an older version of the shell
     before it was implemented).



22.27.2 Math Functions
----------------------


systell(FD)
     The systell math function returns the current file position for
     the file descriptor passed as an argument.



22.27.3 Parameters
------------------


errnos
     A readonly array of the names of errors defined on the system.
     These are typically macros defined in C by including the system
     header file errno.h.  The index of each name (assuming the option
     KSH_ARRAYS is unset) corresponds to the error number.  Error
     numbers NUM before the last known error which have no name are
     given the name ENUM in the array.

     Note that aliases for errors are not handled; only the canonical
     name is used.

sysparams
     A readonly associative array.  The keys are:


    pid
          Returns the process ID of the current process, even in
          subshells.  Compare $$, which returns the process ID of the
          main shell process.

    ppid
          Returns the process ID of the parent of the current process,
          even in subshells.  Compare $PPID, which returns the process
          ID of the parent of the main shell process.

    procsubstpid
          Returns the process ID of the last process started for process
          substitution, i.e. the <(...) and >(...) expansions.




File: zsh.info,  Node: The zsh/net/tcp Module,  Next: The zsh/termcap Module,  Prev: The zsh/system Module,  Up: Zsh Modules

22.28 The zsh/net/tcp Module
============================



   The zsh/net/tcp module makes available one builtin command:


ztcp [ -acflLtv ] [ -d FD ] [ ARGS ]
     ztcp is implemented as a builtin to allow full use of shell
     command line editing, file I/O, and job control mechanisms.

     If ztcp is run with no options, it will output the contents of its
     session table.

     If it is run with only the option -L, it will output the contents
     of the session table in a format suitable for automatic parsing.
     The option is ignored if given with a command to open or close a
     session.  The output consists of a set of lines, one per session,
     each containing the following elements separated by spaces:


    File descriptor
          The file descriptor in use for the connection.  For normal
          inbound (I) and outbound (O) connections this may be read and
          written by the usual shell mechanisms.  However, it should
          only be close with `ztcp -c'.

    Connection type
          A letter indicating how the session was created:


         Z
               A session created with the zftp command.

         L
               A connection opened for listening with `ztcp -l'.

         I
               An inbound connection accepted with `ztcp -a'.

         O
               An outbound connection created with `ztcp HOST ...'.



    The local host
          This is usually set to an all-zero IP address as the address
          of the localhost is irrelevant.

    The local port
          This is likely to be zero unless the connection is for
          listening.

    The remote host
          This is the fully qualified domain name of the peer, if
          available, else an IP address.  It is an all-zero IP address
          for a session opened for listening.

    The remote port
          This is zero for a connection opened for listening.




22.28.1 Outbound Connections
----------------------------




ztcp [ -v ] [ -d FD ] HOST [ PORT ]
     Open a new TCP connection to HOST.  If the PORT is omitted, it
     will default to port 23.  The connection will be added to the
     session table and the shell parameter REPLY will be set to the
     file descriptor associated with that connection.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     In order to elicit more verbose output, use -v.



22.28.2 Inbound Connections
---------------------------




ztcp -l [ -v ] [ -d FD ] PORT
     ztcp -l will open a socket listening on TCP PORT.  The socket will
     be added to the session table and the shell parameter REPLY will
     be set to the file descriptor associated with that listener.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     In order to elicit more verbose output, use -v.

ztcp -a [ -tv ] [ -d TARGETFD ] LISTENFD
     ztcp -a will accept an incoming connection to the port associated
     with LISTENFD.  The connection will be added to the session table
     and the shell parameter REPLY will be set to the file descriptor
     associated with the inbound connection.

     If -d is specified, its argument will be taken as the target file
     descriptor for the connection.

     If -t is specified, ztcp will return if no incoming connection is
     pending.  Otherwise it will wait for one.

     In order to elicit more verbose output, use -v.



22.28.3 Closing Connections
---------------------------




ztcp -cf [ -v ] [ FD ]
ztcp -c [ -v ] [ FD ]
     ztcp -c will close the socket associated with FD.  The socket will
     be removed from the session table.  If FD is not specified, ztcp
     will close everything in the session table.

     Normally, sockets registered by zftp (see *Note The zsh/zftp
     Module:: ) cannot be closed this way.  In order to force such a
     socket closed, use -f.

     In order to elicit more verbose output, use -v.



22.28.4 Example
---------------

Here is how to create a TCP connection between two instances of zsh.  We
need to pick an unassigned port; here we use the randomly chosen 5123.

On host1,
     zmodload zsh/net/tcp
     ztcp -l 5123
     listenfd=$REPLY
     ztcp -a $listenfd
     fd=$REPLY
   The second from last command blocks until there is an incoming
connection.

Now create a connection from host2 (which may, of course, be the same
machine):
     zmodload zsh/net/tcp
     ztcp host1 5123
     fd=$REPLY

Now on each host, $fd contains a file descriptor for talking to the
other.  For example, on host1:
     print This is a message >&$fd
   and on host2:
     read -r line <&$fd; print -r - $line
   prints `This is a message'.

To tidy up, on host1:
     ztcp -c $listenfd
     ztcp -c $fd
   and on host2
     ztcp -c $fd


File: zsh.info,  Node: The zsh/termcap Module,  Next: The zsh/terminfo Module,  Prev: The zsh/net/tcp Module,  Up: Zsh Modules

22.29 The zsh/termcap Module
============================



   The zsh/termcap module makes available one builtin command:


echotc CAP [ ARG ... ]
     Output the termcap value corresponding to the capability CAP, with
     optional arguments.


The zsh/termcap module makes available one parameter:


termcap
     An associative array that maps termcap capability codes to their
     values.



File: zsh.info,  Node: The zsh/terminfo Module,  Next: The zsh/zftp Module,  Prev: The zsh/termcap Module,  Up: Zsh Modules

22.30 The zsh/terminfo Module
=============================



   The zsh/terminfo module makes available one builtin command:


echoti CAP [ ARG ]
     Output the terminfo value corresponding to the capability CAP,
     instantiated with ARG if applicable.


The zsh/terminfo module makes available one parameter:


terminfo
     An associative array that maps terminfo capability names to their
     values.



File: zsh.info,  Node: The zsh/zftp Module,  Next: The zsh/zle Module,  Prev: The zsh/terminfo Module,  Up: Zsh Modules

22.31 The zsh/zftp Module
=========================



   The zsh/zftp module makes available one builtin command:


zftp SUBCOMMAND [ ARGS ]
     The zsh/zftp module is a client for FTP (file transfer protocol).
     It is implemented as a builtin to allow full use of shell command
     line editing, file I/O, and job control mechanisms.  Often, users
     will access it via shell functions providing a more powerful
     interface; a set is provided with the zsh distribution and is
     described in *Note Zftp Function System::.  However, the zftp
     command is entirely usable in its own right.

     All commands consist of the command name zftp followed by the name
     of a subcommand.  These are listed below.  The return status of
     each subcommand is supposed to reflect the success or failure of
     the remote operation.  See a description of the variable
     ZFTP_VERBOSE for more information on how responses from the server
     may be printed.



22.31.1 Subcommands
-------------------




open HOST[:PORT] [ USER [ PASSWORD [ ACCOUNT ] ] ]
     Open a new FTP session to HOST, which may be the name of a TCP/IP
     connected host or an IP number in the standard dot notation.  If
     the argument is in the form HOST:PORT, open a connection to TCP
     port PORT instead of the standard FTP port 21.  This may be the
     name of a TCP service or a number:  see the description of
     ZFTP_PORT below for more information.

     If IPv6 addresses in colon format are used, the HOST should be
     surrounded by quoted square brackets to distinguish it from the
     PORT, for example '[fe80::203:baff:fe02:8b56]'.  For consistency
     this is allowed with all forms of HOST.

     Remaining arguments are passed to the login subcommand.  Note that
     if no arguments beyond HOST are supplied, open will _not_
     automatically call login.  If no arguments at all are supplied,
     open will use the parameters set by the params subcommand.

     After a successful open, the shell variables ZFTP_HOST, ZFTP_PORT,
     ZFTP_IP and ZFTP_SYSTEM are available; see `Variables' below.

login [ NAME [ PASSWORD [ ACCOUNT ] ] ]
user [ NAME [ PASSWORD [ ACCOUNT ] ] ]
     Login the user NAME with parameters PASSWORD and ACCOUNT.  Any of
     the parameters can be omitted, and will be read from standard
     input if needed (NAME is always needed).  If standard input is a
     terminal, a prompt for each one will be printed on standard error
     and PASSWORD will not be echoed.  If any of the parameters are not
     used, a warning message is printed.

     After a successful login, the shell variables ZFTP_USER,
     ZFTP_ACCOUNT and ZFTP_PWD are available; see `Variables' below.

     This command may be re-issued when a user is already logged in, and
     the server will first be reinitialized for a new user.

params [ HOST [ USER [ PASSWORD [ ACCOUNT ] ] ] ]
params -
     Store the given parameters for a later open command with no
     arguments.  Only those given on the command line will be
     remembered.  If no arguments are given, the parameters currently
     set are printed, although the password will appear as a line of
     stars; the return status is one if no parameters were set, zero
     otherwise.

     Any of the parameters may be specified as a `?', which may need to
     be quoted to protect it from shell expansion.  In this case, the
     appropriate parameter will be read from stdin as with the login
     subcommand, including special handling of PASSWORD.  If the `?' is
     followed by a string, that is used as the prompt for reading the
     parameter instead of the default message (any necessary
     punctuation and whitespace should be included at the end of the
     prompt).  The first letter of the parameter (only) may be quoted
     with a `\'; hence an argument "\\$word" guarantees that the string
     from the shell parameter $word will be treated literally, whether
     or not it begins with a `?'.

     If instead a single `-' is given, the existing parameters, if any,
     are deleted.  In that case, calling open with no arguments will
     cause an error.

     The list of parameters is not deleted after a close, however it
     will be deleted if the zsh/zftp module is unloaded.

     For example,


          zftp params ftp.elsewhere.xx juser '?Password for juser: '

     will store the host ftp.elsewhere.xx and the user juser and then
     prompt the user for the corresponding password with the given
     prompt.

test
     Test the connection; if the server has reported that it has closed
     the connection (maybe due to a timeout), return status 2; if no
     connection was open anyway, return status 1; else return status 0.
     The test subcommand is silent, apart from messages printed by the
     $ZFTP_VERBOSE mechanism, or error messages if the connection
     closes.  There is no network overhead for this test.

     The test is only supported on systems with either the select(2) or
     poll(2) system calls; otherwise the message `not supported on this
     system' is printed instead.

     The test subcommand will automatically be called at the start of
     any other subcommand for the current session when a connection is
     open.

cd DIRECTORY
     Change the remote directory to DIRECTORY.  Also alters the shell
     variable ZFTP_PWD.

cdup
     Change the remote directory to the one higher in the directory
     tree.  Note that cd .. will also work correctly on non-UNIX
     systems.

dir [ ARG ... ]
     Give a (verbose) listing of the remote directory.  The ARGs are
     passed directly to the server. The command's behaviour is
     implementation dependent, but a UNIX server will typically
     interpret ARGs as arguments to the ls command and with no
     arguments return the result of `ls -l'. The directory is listed to
     standard output.

ls [ ARG ... ]
     Give a (short) listing of the remote directory.  With no ARG,
     produces a raw list of the files in the directory, one per line.
     Otherwise, up to vagaries of the server implementation, behaves
     similar to dir.

type [ TYPE ]
     Change the type for the transfer to TYPE, or print the current type
     if TYPE is absent.  The allowed values are `A' (ASCII), `I'
     (Image, i.e. binary), or `B' (a synonym for `I').

     The FTP default for a transfer is ASCII.  However, if zftp finds
     that the remote host is a UNIX machine with 8-bit byes, it will
     automatically switch to using binary for file transfers upon open.
     This can subsequently be overridden.

     The transfer type is only passed to the remote host when a data
     connection is established; this command involves no network
     overhead.

ascii
     The same as type A.

binary
     The same as type I.

mode [ S | B ]
     Set the mode type to stream (S) or block (B).  Stream mode is the
     default; block mode is not widely supported.

remote FILE ...
local [ FILE ... ]
     Print the size and last modification time of the remote or local
     files.  If there is more than one item on the list, the name of the
     file is printed first.  The first number is the file size, the
     second is the last modification time of the file in the format
     CCYYMMDDhhmmSS consisting of year, month, date, hour, minutes and
     seconds in GMT.  Note that this format, including the length, is
     guaranteed, so that time strings can be directly compared via the
     [[ builtin's < and > operators, even if they are too long to be
     represented as integers.

     Not all servers support the commands for retrieving this
     information.  In that case, the remote command will print nothing
     and return status 2, compared with status 1 for a file not found.

     The local command (but not remote) may be used with no arguments,
     in which case the information comes from examining file descriptor
     zero.  This is the same file as seen by a put command with no
     further redirection.

get FILE ...
     Retrieve all FILEs from the server, concatenating them and sending
     them to standard output.

put FILE ...
     For each FILE, read a file from standard input and send that to
     the remote host with the given name.

append FILE ...
     As put, but if the remote FILE already exists, data is appended to
     it instead of overwriting it.

getat FILE POINT
putat FILE POINT
appendat FILE POINT
     Versions of get, put and append which will start the transfer at
     the given POINT in the remote FILE.  This is useful for appending
     to an incomplete local file.  However, note that this ability is
     not universally supported by servers (and is not quite the
     behaviour specified by the standard).

delete FILE ...
     Delete the list of files on the server.

mkdir DIRECTORY
     Create a new directory DIRECTORY on the server.

rmdir DIRECTORY
     Delete the directory DIRECTORY  on the server.

rename OLD-NAME NEW-NAME
     Rename file OLD-NAME to NEW-NAME on the server.

site ARG ...
     Send a host-specific command to the server.  You will probably
     only need this if instructed by the server to use it.

quote ARG ...
     Send the raw FTP command sequence to the server.  You should be
     familiar with the FTP command set as defined in RFC959 before doing
     this.  Useful commands may include STAT and HELP.  Note also the
     mechanism for returning messages as described for the variable
     ZFTP_VERBOSE below, in particular that all messages from the
     control connection are sent to standard error.

close
quit
     Close the current data connection.  This unsets the shell
     parameters ZFTP_HOST, ZFTP_PORT, ZFTP_IP, ZFTP_SYSTEM, ZFTP_USER,
     ZFTP_ACCOUNT, ZFTP_PWD, ZFTP_TYPE and ZFTP_MODE.

session [ SESSNAME ]
     Allows multiple FTP sessions to be used at once.  The name of the
     session is an arbitrary string of characters; the default session
     is called `default'.  If this command is called without an
     argument, it will list all the current sessions; with an argument,
     it will either switch to the existing session called SESSNAME, or
     create a new session of that name.

     Each session remembers the status of the connection, the set of
     connection-specific shell parameters (the same set as are unset
     when a connection closes, as given in the description of close),
     and any user parameters specified with the params subcommand.
     Changing to a previous session restores those values; changing to
     a new session initialises them in the same way as if zftp had just
     been loaded.  The name of the current session is given by the
     parameter ZFTP_SESSION.

rmsession [ SESSNAME ]
     Delete a session; if a name is not given, the current session is
     deleted.  If the current session is deleted, the earliest existing
     session becomes the new current session, otherwise the current
     session is not changed.  If the session being deleted is the only
     one, a new session called `default' is created and becomes the
     current session; note that this is a new session even if the
     session being deleted is also called `default'. It is recommended
     that sessions not be deleted while background commands which use
     zftp are still active.



22.31.2 Parameters
------------------

The following shell parameters are used by zftp.  Currently none of
them are special.


ZFTP_TMOUT
     Integer.  The time in seconds to wait for a network operation to
     complete before returning an error.  If this is not set when the
     module is loaded, it will be given the default value 60.  A value
     of zero turns off timeouts.  If a timeout occurs on the control
     connection it will be closed.  Use a larger value if this occurs
     too frequently.

ZFTP_IP
     Readonly.  The IP address of the current connection in dot
     notation.

ZFTP_HOST
     Readonly.  The hostname of the current remote server.  If the host
     was opened as an IP number, ZFTP_HOST contains that instead; this
     saves the overhead for a name lookup, as IP numbers are most
     commonly used when a nameserver is unavailable.

ZFTP_PORT
     Readonly.  The number of the remote TCP port to which the
     connection is open (even if the port was originally specified as a
     named service).  Usually this is the standard FTP port, 21.

     In the unlikely event that your system does not have the
     appropriate conversion functions, this appears in network byte
     order.  If your system is little-endian, the port then consists of
     two swapped bytes and the standard port will be reported as 5376.
     In that case, numeric ports passed to zftp open will also need to
     be in this format.

ZFTP_SYSTEM
     Readonly.  The system type string returned by the server in
     response to an FTP SYST request.  The most interesting case is a
     string beginning "UNIX Type: L8", which ensures maximum
     compatibility with a local UNIX host.

ZFTP_TYPE
     Readonly.  The type to be used for data transfers , either `A' or
     `I'.   Use the type subcommand to change this.

ZFTP_USER
     Readonly.  The username currently logged in, if any.

ZFTP_ACCOUNT
     Readonly.  The account name of the current user, if any.  Most
     servers do not require an account name.

ZFTP_PWD
     Readonly.  The current directory on the server.

ZFTP_CODE
     Readonly.  The three digit code of the last FTP reply from the
     server as a string.  This can still be read after the connection
     is closed, and is not changed when the current session changes.

ZFTP_REPLY
     Readonly.  The last line of the last reply sent by the server.
     This can still be read after the connection is closed, and is not
     changed when the current session changes.

ZFTP_SESSION
     Readonly.  The name of the current FTP session; see the
     description of the session subcommand.

ZFTP_PREFS
     A string of preferences for altering aspects of zftp's behaviour.
     Each preference is a single character.  The following are defined:


    P
          Passive:  attempt to make the remote server initiate data
          transfers.  This is slightly more efficient than sendport
          mode.  If the letter S occurs later in the string, zftp will
          use sendport mode if passive mode is not available.

    S
          Sendport:  initiate transfers by the FTP PORT command.  If
          this occurs before any P in the string, passive mode will
          never be attempted.

    D
          Dumb:  use only the bare minimum of FTP commands.  This
          prevents the variables ZFTP_SYSTEM and ZFTP_PWD from being
          set, and will mean all connections default to ASCII type.  It
          may prevent ZFTP_SIZE from being set during a transfer if the
          server does not send it anyway (many servers do).


     If ZFTP_PREFS is not set when zftp is loaded, it will be set to a
     default of `PS', i.e. use passive mode if available, otherwise
     fall back to sendport mode.

ZFTP_VERBOSE
     A string of digits between 0 and 5 inclusive, specifying which
     responses from the server should be printed.  All responses go to
     standard error.  If any of the numbers 1 to 5 appear in the string,
     raw responses from the server with reply codes beginning with that
     digit will be printed to standard error.  The first digit of the
     three digit reply code is defined by RFC959 to correspond to:


    1.
          A positive preliminary reply.

    2.
          A positive completion reply.

    3.
          A positive intermediate reply.

    4.
          A transient negative completion reply.

    5.
          A permanent negative completion reply.


     It should be noted that, for unknown reasons, the reply `Service
     not available', which forces termination of a connection, is
     classified as 421, i.e. `transient negative', an interesting
     interpretation of the word `transient'.

     The code 0 is special:  it indicates that all but the last line of
     multiline replies read from the server will be printed to standard
     error in a processed format.  By convention, servers use this
     mechanism for sending information for the user to read.  The
     appropriate reply code, if it matches the same response, takes
     priority.

     If ZFTP_VERBOSE is not set when zftp is loaded, it will be set to
     the default value 450, i.e., messages destined for the user and
     all errors will be printed.  A null string is valid and specifies
     that no messages should be printed.



22.31.3 Functions
-----------------




zftp_chpwd
     If this function is set by the user, it is called every time the
     directory changes on the server, including when a user is logged
     in, or when a connection is closed.  In the last case, $ZFTP_PWD
     will be unset; otherwise it will reflect the new directory.

zftp_progress
     If this function is set by the user, it will be called during a
     get, put or append operation each time sufficient data has been
     received from the host.  During a get, the data is sent to
     standard output, so it is vital that this function should write to
     standard error or directly to the terminal, _not_ to standard
     output.

     When it is called with a transfer in progress, the following
     additional shell parameters are set:


    ZFTP_FILE
          The name of the remote file being transferred from or to.

    ZFTP_TRANSFER
          A G for a get operation and a P for a put operation.

    ZFTP_SIZE
          The total size of the complete file being transferred: the
          same as the first value provided by the remote and local
          subcommands for a particular file.  If the server cannot
          supply this value for a remote file being retrieved, it will
          not be set.  If input is from a pipe the value may be
          incorrect and correspond simply to a full pipe buffer.

    ZFTP_COUNT
          The amount of data so far transferred; a number between zero
          and $ZFTP_SIZE, if that is set.  This number is always
          available.


     The function is initially called with ZFTP_TRANSFER set
     appropriately and ZFTP_COUNT set to zero.  After the transfer is
     finished, the function will be called one more time with
     ZFTP_TRANSFER set to GF or PF, in case it wishes to tidy up.  It
     is otherwise never called twice with the same value of ZFTP_COUNT.

     Sometimes the progress meter may cause disruption.  It is up to the
     user to decide whether the function should be defined and to use
     unfunction when necessary.



22.31.4 Problems
----------------



A connection may not be opened in the left hand side of a pipe as this
occurs in a subshell and the file information is not updated in the main
shell.  In the case of type or mode changes or closing the connection
in a subshell, the information is returned but variables are not
updated until the next call to zftp.  Other status changes in subshells
will not be reflected by changes to the variables (but should be
otherwise harmless).

Deleting sessions while a zftp command is active in the background can
have unexpected effects, even if it does not use the session being
deleted.  This is because all shell subprocesses share information on
the state of all connections, and deleting a session changes the
ordering of that information.

On some operating systems, the control connection is not valid after a
fork(), so that operations in subshells, on the left hand side of a
pipeline, or in the background are not possible, as they should be.
This is presumably a bug in the operating system.


File: zsh.info,  Node: The zsh/zle Module,  Next: The zsh/zleparameter Module,  Prev: The zsh/zftp Module,  Up: Zsh Modules

22.32 The zsh/zle Module
========================



   The zsh/zle module contains the Zsh Line Editor.  See *Note Zsh Line
Editor::.


File: zsh.info,  Node: The zsh/zleparameter Module,  Next: The zsh/zprof Module,  Prev: The zsh/zle Module,  Up: Zsh Modules

22.33 The zsh/zleparameter Module
=================================



   The zsh/zleparameter module defines two special parameters that can
be used to access internal information of the Zsh Line Editor (see
*Note Zsh Line Editor::).


keymaps
     This array contains the names of the keymaps currently defined.

widgets
     This associative array contains one entry per widget. The name of
     the widget is the key and the value gives information about the
     widget. It is either   the string `builtin' for builtin widgets,
     a string of the form `user:NAME' for user-defined widgets,
     where NAME is the name of the shell function implementing the
     widget,   a string of the form `completion:TYPE:NAME'     for
     completion widgets,   or a null value if the widget is not yet
     fully defined.  In the penultimate case, TYPE is the name of the
     builtin widget the completion widget imitates in its behavior and
     NAME is the name of the shell function implementing the completion
     widget.



File: zsh.info,  Node: The zsh/zprof Module,  Next: The zsh/zpty Module,  Prev: The zsh/zleparameter Module,  Up: Zsh Modules

22.34 The zsh/zprof Module
==========================



   When loaded, the zsh/zprof causes shell functions to be profiled.
The profiling results can be obtained with the zprof builtin command
made available by this module.  There is no way to turn profiling off
other than unloading the module.


zprof [ -c ]
     Without the -c option, zprof lists profiling results to standard
     output.  The format is comparable to that of commands like gprof.

     At the top there is a summary listing all functions that were
     called at least once.  This summary is sorted in decreasing order
     of the amount of time spent in each.  The lines contain the number
     of the function in order, which is used in other parts of the list
     in suffixes of the form `[NUM]', then the number of calls made to
     the function.  The next three columns list the time in
     milliseconds spent in the function and its descendants, the average
     time in milliseconds spent in the function and its descendants per
     call and the percentage of time spent in all shell functions used
     in this function and its descendants.  The following three columns
     give the same information, but counting only the time spent in the
     function itself.  The final column shows the name of the function.

     After the summary, detailed information about every function that
     was invoked is listed, sorted in decreasing order of the amount of
     time spent in each function and its descendants.  Each of these
     entries consists of descriptions for the functions that called the
     function described, the function itself, and the functions that
     were called from it.  The description for the function itself has
     the same format as in the summary (and shows the same
     information).  The other lines don't show the number of the
     function at the beginning and have their function named indented to
     make it easier to distinguish the line showing the function
     described in the section from the surrounding lines.

     The information shown in this case is almost the same as in the
     summary, but only refers to the call hierarchy being displayed.
     For example, for a calling function the column showing the total
     running time lists the time spent in the described function and
     its descendants only for the times when it was called from that
     particular calling function.  Likewise, for a called function,
     this columns lists the total time spent in the called function and
     its descendants only for the times when it was called from the
     function described.

     Also in this case, the column showing the number of calls to a
     function also shows a slash and then the total number of
     invocations made to the called function.

     As long as the zsh/zprof module is loaded, profiling will be done
     and multiple invocations of the zprof builtin command will show the
     times and numbers of calls since the module was loaded.  With the
     -c option, the zprof builtin command will reset its internal
     counters and will not show the listing.



File: zsh.info,  Node: The zsh/zpty Module,  Next: The zsh/zselect Module,  Prev: The zsh/zprof Module,  Up: Zsh Modules

22.35 The zsh/zpty Module
=========================



   The zsh/zpty module offers one builtin:


zpty [ -e ] [ -b ] NAME [ ARG ... ]
     The arguments following NAME are concatenated with spaces between,
     then executed as a command, as if passed to the eval builtin.  The
     command runs under a newly assigned pseudo-terminal; this is
     useful for running commands non-interactively which expect an
     interactive environment.  The NAME is not part of the command, but
     is used to refer to this command in later calls to zpty.

     With the -e option, the pseudo-terminal is set up so that input
     characters are echoed.

     With the -b option, input to and output from the pseudo-terminal
     are made non-blocking.

     The shell parameter REPLY is set to the file descriptor assigned to
     the master side of the pseudo-terminal.  This allows the terminal
     to be monitored with ZLE descriptor handlers (see *Note Zle
     Builtins::) or manipulated with sysread and syswrite (see *Note
     The zsh/system Module::).  _Warning_: Use of sysread and syswrite
     is _not_ recommended; use zpty -r and zpty -w unless you know
     exactly what you are doing.

zpty -d [ NAME ... ]
     The second form, with the -d option, is used to delete commands
     previously started, by supplying a list of their NAMEs.  If no
     NAME is given, all commands are deleted.  Deleting a command causes
     the HUP signal to be sent to the corresponding process.

zpty -w [ -n ] NAME [ STRING ... ]
     The -w option can be used to send the to command NAME the given
     STRINGs as input (separated by spaces).  If the -n option is _not_
     given, a newline is added at the end.

     If no STRING is provided, the standard input is copied to the
     pseudo-terminal; this may stop before copying the full input if the
     pseudo-terminal is non-blocking.  The exact input is always copied:
     the -n option is not applied.

     Note that the command under the pseudo-terminal sees this input as
     if it were typed, so beware when sending special tty driver
     characters such as word-erase, line-kill, and end-of-file.

zpty -r [ -mt ] NAME [ PARAM [ PATTERN ] ]
     The -r option can be used to read the output of the command NAME.
     With only a NAME argument, the output read is copied to the
     standard output.  Unless the pseudo-terminal is non-blocking,
     copying continues until the command under the pseudo-terminal
     exits; when non-blocking, only as much output as is immediately
     available is copied.  The return status is zero if any output is
     copied.

     When also given a PARAM argument, at most one line is read and
     stored in the parameter named PARAM.  Less than a full line may be
     read if the pseudo-terminal is non-blocking.  The return status is
     zero if at least one character is stored in PARAM.

     If a PATTERN is given as well, output is read until the whole
     string read matches the PATTERN, even in the non-blocking case.
     The return status is zero if the string read matches the pattern,
     or if the command has exited but at least one character could
     still be read.  If the option -m is present, the return status is
     zero only if the pattern matches.  As of this writing, a maximum
     of one megabyte of output can be consumed this way; if a full
     megabyte is read without matching the pattern, the return status
     is non-zero.

     In all cases, the return status is non-zero if nothing could be
     read, and is 2 if this is because the command has finished.

     If the -r option is combined with the -t option, zpty tests
     whether output is available before trying to read.  If no output is
     available, zpty immediately returns the status 1.  When used with
     a PATTERN, the behaviour on a failed poll is similar to when the
     command has exited:  the return value is zero if at least one
     character could still be read even if the pattern failed to match.

zpty -t NAME
     The -t option without the -r option can be used to test whether
     the command NAME is still running.  It returns a zero status if
     the command is running and a non-zero value otherwise.

zpty [ -L ]
     The last form, without any arguments, is used to list the commands
     currently defined.  If the -L option is given, this is done in the
     form of calls to the zpty builtin.



File: zsh.info,  Node: The zsh/zselect Module,  Next: The zsh/zutil Module,  Prev: The zsh/zpty Module,  Up: Zsh Modules

22.36 The zsh/zselect Module
============================



   The zsh/zselect module makes available one builtin command:


zselect [ -rwe ] [ -t TIMEOUT ] [ -a ARRAY ] [ -A ASSOC ] [ FD ... ]
     The zselect builtin is a front-end to the `select' system call,
     which blocks until a file descriptor is ready for reading or
     writing, or has an error condition, with an optional timeout.  If
     this is not available on your system, the command prints an error
     message and returns status 2 (normal errors return status 1).  For
     more information, see your systems documentation for man page
     select(3).  Note there is no connection with the shell builtin of
     the same name.

     Arguments and options may be intermingled in any order.  Non-option
     arguments are file descriptors, which must be decimal integers.  By
     default, file descriptors are to be tested for reading, i.e.
     zselect will return when data is available to be read from the
     file descriptor, or more precisely, when a read operation from the
     file descriptor will not block.  After a -r, -w and -e, the given
     file descriptors are to be tested for reading, writing, or error
     conditions.  These options and an arbitrary list of file
     descriptors may be given in any order.

     (The presence of an `error condition' is not well defined in the
     documentation for many implementations of the select system call.
     According to recent versions of the POSIX specification, it is
     really an _exception_ condition, of which the only standard
     example is out-of-band data received on a socket.  So zsh users
     are unlikely to find the -e option useful.)

     The option `-t TIMEOUT' specifies a timeout in hundredths of a
     second.  This may be zero, in which case the file descriptors will
     simply be polled and zselect will return immediately.  It is
     possible to call zselect with no file descriptors and a non-zero
     timeout for use as a finer-grained replacement for `sleep'; note,
     however, the return status is always 1 for a timeout.

     The option `-a ARRAY' indicates that ARRAY should be set to
     indicate the file descriptor(s) which are ready.  If the option is
     not given, the array reply will be used for this purpose.  The
     array will contain a string similar to the arguments for zselect.
     For example,


          zselect -t 0 -r 0 -w 1

     might return immediately with status 0 and $reply containing `-r 0
     -w 1' to show that both file descriptors are ready for the
     requested operations.

     The option `-A ASSOC' indicates that the associative array ASSOC
     should be set to indicate the file descriptor(s) which are ready.
     This option overrides the option -a, nor will reply be modified.
     The keys of assoc are the file descriptors, and the corresponding
     values are any of the characters `rwe' to indicate the condition.

     The command returns status 0 if some file descriptors are ready for
     reading.  If the operation timed out, or a timeout of 0 was given
     and no file descriptors were ready, or there was an error, it
     returns status 1 and the array will not be set (nor modified in
     any way).  If there was an error in the select operation the
     appropriate error message is printed.



File: zsh.info,  Node: The zsh/zutil Module,  Prev: The zsh/zselect Module,  Up: Zsh Modules

22.37 The zsh/zutil Module
==========================



   The zsh/zutil module only adds some builtins:


zstyle [ -L [ METAPATTERN [ STYLE ] ] ]
zstyle [ -e | - | -- ] PATTERN STYLE STRING ...
zstyle -d [ PATTERN [ STYLE ... ] ]
zstyle -g NAME [ PATTERN [ STYLE ] ]
zstyle -{a|b|s} CONTEXT STYLE NAME [ SEP ]
zstyle -{T|t} CONTEXT STYLE [ STRING ... ]
zstyle -m CONTEXT STYLE PATTERN
     This builtin command is used to define and lookup styles.  Styles
     are pairs of names and values, where the values consist of any
     number of strings.  They are stored together with patterns and
     lookup is done by giving a string, called the `_context_', which
     is matched against the patterns.  The definition stored for the
     most specific pattern that matches will be returned.

     A pattern is considered to be more specific than another if it
     contains more components (substrings separated by colons) or if
     the patterns for the components are more specific, where simple
     strings are considered to be more specific than patterns and
     complex patterns are considered to be more specific than the
     pattern `*'.  A `*' in the pattern will match zero or more
     characters in the context; colons are not treated specially in
     this regard.  If two patterns are equally specific, the tie is
     broken in favour of the pattern that was defined first.

     _Example_

     For example, to define your preferred form of precipitation
     depending on which city you're in, you might set the following in
     your zshrc:


          zstyle ':weather:europe:*' preferred-precipitation rain
          zstyle ':weather:europe:germany:* preferred-precipitation none
          zstyle ':weather:europe:germany:*:munich' preferred-precipitation snow

     Then, the fictional `weather' plugin might run under the hood a
     command such as


          zstyle -s ":weather:${continent}:${country}:${county}:${city}" preferred-precipitation REPLY

     in order to retrieve your preference into the scalar variable
     $REPLY.

     _Usage_

     The forms that operate on patterns are the following.


    zstyle [ -L [ METAPATTERN [ STYLE ] ] ]
          Without arguments, lists style definitions.  Styles are shown
          in alphabetic order and patterns are shown in the order
          zstyle will test them.

          If the -L option is given, listing is done in the form of
          calls to zstyle.  The optional first argument, METAPATTERN,
          is a pattern which will be matched against the string
          supplied as PATTERN when the style was defined.  Note: this
          means, for example, `zstyle -L ":completion:*"' will match
          any supplied pattern beginning `:completion:', not just
          ":completion:*":  use ':completion:\*' to match that.  The
          optional second argument limits the output to a specific
          STYLE (not a pattern).  -L is not compatible with any other
          options.

    zstyle [ - | -- | -e ] PATTERN STYLE STRING ...
          Defines the given STYLE for the PATTERN with the STRINGs as
          the value.  If the -e option is given, the STRINGs will be
          concatenated (separated by spaces) and the resulting string
          will be evaluated (in the same way as it is done by the eval
          builtin command) when the style is looked up.  In this case
          the parameter `reply' must be assigned to set the strings
          returned after the evaluation.  Before evaluating the value,
          reply is unset, and if it is still unset after the
          evaluation, the style is treated as if it were not set.

    zstyle -d [ PATTERN [ STYLE ... ] ]
          Delete style definitions. Without arguments all definitions
          are deleted, with a PATTERN all definitions for that pattern
          are deleted and if any STYLEs are given, then only those
          styles are deleted for the PATTERN.

    zstyle -g NAME [ PATTERN [ STYLE ] ]
          Retrieve a style definition. The NAME is used as the name of
          an array in which the results are stored. Without any further
          arguments, all patterns defined are returned. With a PATTERN
          the styles defined for that pattern are returned and with
          both a PATTERN and a STYLE, the value strings of that
          combination is returned.


     The other forms can be used to look up or test styles for a given
     context.


    zstyle -s CONTEXT STYLE NAME [ SEP ]
          The parameter NAME is set to the value of the style
          interpreted as a string.  If the value contains several
          strings they are concatenated with spaces (or with the SEP
          string if that is given) between them.

          Return 0 if the style is set, 1 otherwise.

    zstyle -b CONTEXT STYLE NAME
          The value is stored in NAME as a boolean, i.e. as the string
          `yes' if the value has only one string and that string is
          equal to one of `yes', `true', `on', or `1'. If the value is
          any other string or has more than one string, the parameter
          is set to `no'.

          Return 0 if NAME is set to `yes', 1 otherwise.

    zstyle -a CONTEXT STYLE NAME
          The value is stored in NAME as an array. If NAME is declared
          as an associative array,  the first, third, etc. strings are
          used as the keys and the other strings are used as the values.

          Return 0 if the style is set, 1 otherwise.

    zstyle -t CONTEXT STYLE [ STRING ... ]
    zstyle -T CONTEXT STYLE [ STRING ... ]
          Test the value of a style, i.e. the -t option only returns a
          status (sets $?).  Without any STRING the return status is
          zero if the style is defined for at least one matching
          pattern, has only one string in its value, and that is equal
          to one of `true', `yes', `on' or `1'. If any STRINGs are
          given the status is zero if and only if at least one of the
          STRINGs is equal to at least one of the strings in the value.
          If the style is defined but doesn't match, the return status
          is 1. If the style is not defined, the status is 2.

          The -T option tests the values of the style like -t, but it
          returns status zero (rather than 2) if the style is not
          defined for any matching pattern.

    zstyle -m CONTEXT STYLE PATTERN
          Match a value. Returns status zero if the PATTERN matches at
          least one of the strings in the value.


zformat -f PARAM FORMAT SPEC ...
zformat -a ARRAY SEP SPEC ...
     This builtin provides two different forms of formatting. The first
     form is selected with the -f option. In this case the FORMAT
     string will be modified by replacing sequences starting with a
     percent sign in it with strings from the SPECs.  Each SPEC should
     be of the form `CHAR:STRING' which will cause every appearance of
     the sequence `%CHAR' in FORMAT to be replaced by the STRING.  The
     `%' sequence may also contain optional minimum and maximum field
     width specifications between the `%' and the `CHAR' in the form
     `%MIN.MAXc', i.e. the minimum field width is given first and if
     the maximum field width is used, it has to be preceded by a dot.
     Specifying a minimum field width makes the result be padded with
     spaces to the right if the STRING is shorter than the requested
     width.  Padding to the left can be achieved by giving a negative
     minimum field width.  If a maximum field width is specified, the
     STRING will be truncated after that many characters.  After all
     `%' sequences for the given SPECs have been processed, the
     resulting string is stored in the parameter PARAM.

     The %-escapes also understand ternary expressions in the form used
     by prompts.  The % is followed by a `(' and then an ordinary
     format specifier character as described above.  There may be a set
     of digits either before or after the `('; these specify a test
     number, which defaults to zero.  Negative numbers are also
     allowed.  An arbitrary delimiter character follows the format
     specifier, which is followed by a piece of `true' text, the
     delimiter character again, a piece of `false' text, and a closing
     parenthesis.  The complete expression (without the digits) thus
     looks like `%(X.TEXT1.TEXT2)', except that the `.' character is
     arbitrary.  The value given for the format specifier in the
     CHAR:STRING expressions is evaluated as a mathematical expression,
     and compared with the test number.  If they are the same, TEXT1 is
     output, else TEXT2 is output.  A parenthesis may be escaped in
     TEXT2 as %).  Either of TEXT1 or TEXT2 may contain nested
     %-escapes.

     For example:


          zformat -f REPLY "The answer is '%3(c.yes.no)'." c:3

     outputs "The answer is 'yes'." to REPLY since the value for the
     format specifier c is 3, agreeing with the digit argument to the
     ternary expression.

     The second form, using the -a option, can be used for aligning
     strings.  Here, the SPECs are of the form `LEFT:RIGHT' where
     `LEFT' and `RIGHT' are arbitrary strings.  These strings are
     modified by replacing the colons by the SEP string and padding the
     LEFT strings with spaces to the right so that the SEP strings in
     the result (and hence the RIGHT strings after them) are all
     aligned if the strings are printed below each other.  All strings
     without a colon are left unchanged and all strings with an empty
     RIGHT string have the trailing colon removed.  In both cases the
     lengths of the strings are not used to determine how the other
     strings are to be aligned.  A colon in the LEFT string can be
     escaped with a backslash.  The resulting strings are stored in the
     ARRAY.

zregexparse
     This implements some internals of the _regex_arguments function.

zparseopts [ -D -E -F -K -M ] [ -a ARRAY ] [ -A ASSOC ] [ - ] SPEC ...
     This builtin simplifies the parsing of options in positional
     parameters, i.e. the set of arguments given by $*.  Each SPEC
     describes one option and must be of the form `OPT[=ARRAY]'.  If an
     option described by OPT is found in the positional parameters it
     is copied into the ARRAY specified with the -a option; if the
     optional `=ARRAY' is given, it is instead copied into that array,
     which should be declared as a normal array and never as an
     associative array.

     Note that it is an error to give any SPEC without an `=ARRAY'
     unless one of the -a or -A options is used.

     Unless the -E option is given, parsing stops at the first string
     that isn't described by one of the SPECs.  Even with -E, parsing
     always stops at a positional parameter equal to `-' or `--'. See
     also -F.

     The OPT description must be one of the following.  Any of the
     special characters can appear in the option name provided it is
     preceded by a backslash.


    NAME
    NAME+
          The NAME is the name of the option without the leading `-'.
          To specify a GNU-style long option, one of the usual two
          leading `-' must be included in NAME; for example, a `--file'
          option is represented by a NAME of `-file'.

          If a `+' appears after NAME, the option is appended to ARRAY
          each time it is found in the positional parameters; without
          the `+' only the _last_ occurrence of the option is preserved.

          If one of these forms is used, the option takes no argument,
          so parsing stops if the next positional parameter does not
          also begin with `-' (unless the -E option is used).

    NAME:
    NAME:-
    NAME::
          If one or two colons are given, the option takes an argument;
          with one colon, the argument is mandatory and with two colons
          it is optional.  The argument is appended to the ARRAY after
          the option itself.

          An optional argument is put into the same array element as
          the option name (note that this makes empty strings as
          arguments indistinguishable).  A mandatory argument is added
          as a separate element unless the `:-' form is used, in which
          case the argument is put into the same element.

          A `+' as described above may appear between the NAME and the
          first colon.


     In all cases, option-arguments must appear either immediately
     following the option in the same positional parameter or in the
     next one. Even an optional argument may appear in the next
     parameter, unless it begins with a `-'.  There is no special
     handling of `=' as with GNU-style argument parsers; given the SPEC
     `-foo:', the positional parameter `--foo=bar' is parsed as `--foo'
     with an argument of `=bar'.

     When the names of two options that take no arguments overlap, the
     longest one wins, so that parsing for the SPECs `-foo -foobar'
     (for example) is unambiguous. However, due to the aforementioned
     handling of option-arguments, ambiguities may arise when at least
     one overlapping SPEC takes an argument, as in `-foo: -foobar'. In
     that case, the last matching SPEC wins.

     The options of zparseopts itself cannot be stacked because, for
     example, the stack `-DEK' is indistinguishable from a SPEC for the
     GNU-style long option `--DEK'.  The options of zparseopts itself
     are:


    -a ARRAY
          As described above, this names the default array in which to
          store the recognised options.

    -A ASSOC
          If this is given, the options and their values are also put
          into an associative array with the option names as keys and
          the arguments (if any) as the values.

    -D
          If this option is given, all options found are removed from
          the positional parameters of the calling shell or shell
          function, up to but not including any not described by the
          SPECs.  If the first such parameter is `-' or `--', it is
          removed as well.  This is similar to using the shift builtin.

    -E
          This changes the parsing rules to _not_ stop at the first
          string that isn't described by one of the SPECs.  It can be
          used to test for or (if used together with -D) extract
          options and their arguments, ignoring all other options and
          arguments that may be in the positional parameters.  As
          indicated above, parsing still stops at the first `-' or `--'
          not described by a SPEC, but it is not removed when used with
          -D.

    -F
          If this option is given, zparseopts immediately stops at the
          first option-like parameter not described by one of the
          SPECs, prints an error message, and returns status 1.
          Removal (-D) and extraction (-E) are not performed, and
          option arrays are not updated.  This provides basic
          validation for the given options.

          Note that the appearance in the positional parameters of an
          option without its required argument always aborts parsing
          and returns an error as described above regardless of whether
          this option is used.

    -K
          With this option, the arrays specified with the -a option and
          with the `=ARRAY' forms are kept unchanged when none of the
          SPECs for them is used.  Otherwise the entire array is
          replaced when any of the SPECs is used.  Individual elements
          of associative arrays specified with the -A option are
          preserved by -K.  This allows assignment of default values to
          arrays before calling zparseopts.

    -M
          This changes the assignment rules to implement a map among
          equivalent option names.  If any SPEC uses the `=ARRAY' form,
          the string ARRAY is interpreted as the name of another SPEC,
          which is used to choose where to store the values.  If no
          other SPEC is found, the values are stored as usual.  This
          changes only the way the values are stored, not the way $* is
          parsed, so results may be unpredictable if the `NAME+'
          specifier is used inconsistently.


     For example,


          set -- -a -bx -c y -cz baz -cend
          zparseopts a=foo b:=bar c+:=bar

     will have the effect of


          foo=(-a)
          bar=(-b x -c y -c z)

     The arguments from `baz' on will not be used.

     As an example for the -E option, consider:


          set -- -a x -b y -c z arg1 arg2
          zparseopts -E -D b:=bar

     will have the effect of


          bar=(-b y)
          set -- -a x -c z arg1 arg2

     I.e., the option -b and its arguments are taken from the
     positional parameters and put into the array bar.

     The -M option can be used like this:


          set -- -a -bx -c y -cz baz -cend
          zparseopts -A bar -M a=foo b+: c:=b

     to have the effect of


          foo=(-a)
          bar=(-a '' -b xyz)



File: zsh.info,  Node: Calendar Function System,  Next: TCP Function System,  Prev: Zsh Modules,  Up: Top

23 Calendar Function System
***************************



23.1 Description
================

The shell is supplied with a series of functions to replace and enhance
the traditional Unix calendar programme, which warns the user of
imminent or future events, details of which are stored in a text file
(typically calendar in the user's home directory).  The version
provided here includes a mechanism for alerting the user when an event
is due.

In addition functions age, before and after are provided that can be
used in a glob qualifier; they allow files to be selected based on
their modification times.

The format of the calendar file and the dates used there in and in the
age function are described first, then the functions that can be called
to examine and modify the calendar file.

The functions here depend on the availability of the zsh/datetime
module which is usually installed with the shell.  The library function
strptime() must be available; it is present on most recent operating
systems.



* Menu:

* Calendar File and Date Formats::
* Calendar System User Functions::
* Calendar Styles::
* Calendar Utility Functions::
* Calendar Bugs::



File: zsh.info,  Node: Calendar File and Date Formats,  Next: Calendar System User Functions,  Up: Calendar Function System

23.2 File and Date Formats
==========================



23.2.1 Calendar File Format
---------------------------

The calendar file is by default ~/calendar.  This can be configured by
the calendar-file style, see *Note Calendar Styles::.  The basic format
consists of a series of separate lines, with no indentation, each
including a date and time specification followed by a description of
the event.

Various enhancements to this format are supported, based on the syntax
of Emacs calendar mode.  An indented line indicates a continuation line
that continues the description of the event from the preceding line
(note the date may not be continued in this way).  An initial ampersand
(&) is ignored for compatibility.

An indented line on which the first non-whitespace character is # is
not displayed with the calendar entry, but is still scanned for
information.  This can be used to hide information useful to the
calendar system but not to the user, such as the unique identifier used
by calendar_add.

The Emacs extension that a date with no description may refer to a
number of succeeding events at different times is not supported.

Unless the done-file style has been altered, any events which have been
processed are appended to the file with the same name as the calendar
file with the suffix .done, hence ~/calendar.done by default.

An example is shown below.



23.2.2 Date Format
------------------

The format of the date and time is designed to allow flexibility without
admitting ambiguity.  (The words `date' and `time' are both used in the
documentation below; except where specifically noted this implies a
string that may include both a date and a time specification.)  Note
that there is no localization support; month and day names must be in
English and separator characters are fixed.  Matching is case
insensitive, and only the first three letters of the names are
significant, although as a special case a form beginning "month" does
not match "Monday".  Furthermore, time zones are not handled; all times
are assumed to be local.

It is recommended that, rather than exploring the intricacies of the
system, users find a date format that is natural to them and stick to
it.  This will avoid unexpected effects.  Various key facts should be
noted.


   * In particular, note the confusion between MONTH/DAY/YEAR and
     DAY/MONTH/YEAR when the month is numeric; these formats should be
     avoided if at all possible.  Many alternatives are available.

   * The year must be given in full to avoid confusion, and only years
     from 1900 to 2099 inclusive are matched.

The following give some obvious examples; users finding here a format
they like and not subject to vagaries of style may skip the full
description.  As dates and times are matched separately (even though
the time may be embedded in the date), any date format may be mixed
with any format for the time of day provide the separators are clear
(whitespace, colons, commas).


     2007/04/03 13:13
     2007/04/03:13:13
     2007/04/03 1:13 pm
     3rd April 2007, 13:13
     April 3rd 2007 1:13 p.m.
     Apr 3, 2007 13:13
     Tue Apr 03 13:13:00 2007
     13:13 2007/apr/3

More detailed rules follow.

Times are parsed and extracted before dates.  They must use colons to
separate hours and minutes, though a dot is allowed before seconds if
they are present.  This limits time formats to the following:


   * HH:MM[:SS[.FFFFF]] [am|pm|a.m.|p.m.]

   * HH:MM.SS[.FFFFF] [am|pm|a.m.|p.m.]

Here, square brackets indicate optional elements, possibly with
alternatives.  Fractions of a second are recognised but ignored.  For
absolute times (the normal format require by the calendar file and the
age, before and after functions) a date is mandatory but a time of day
is not; the time returned is at the start of the date.  One variation
is allowed: if a.m. or p.m. or one of their variants is present, an
hour without a minute is allowed, e.g. 3 p.m..

Time zones are not handled, though if one is matched following a time
specification it will be removed to allow a surrounding date to be
parsed.  This only happens if the format of the timezone is not too
unusual.  The following are examples of forms that are understood:


     +0100
     GMT
     GMT-7
     CET+1CDT

Any part of the timezone that is not numeric must have exactly three
capital letters in the name.

Dates suffer from the ambiguity between DD/MM/YYYY and MM/DD/YYYY.  It
is recommended this form is avoided with purely numeric dates, but use
of ordinals, eg. 3rd/04/2007, will resolve the ambiguity as the ordinal
is always parsed as the day of the month.  Years must be four digits
(and the first two must be 19 or 20); 03/04/08 is not recognised.  Other
numbers may have leading zeroes, but they are not required.  The
following are handled:


   * YYYY/MM/DD

   * YYYY-MM-DD

   * YYYY/MNM/DD

   * YYYY-MNM-DD

   * DD[th|st|rd] MNM[,] [ YYYY ]

   * MNM DD[th|st|rd][,] [ YYYY ]

   * DD[th|st|rd]/MM[,] YYYY

   * DD[th|st|rd]/MM/YYYY

   * MM/DD[th|st|rd][,] YYYY

   * MM/DD[th|st|rd]/YYYY

Here, MNM is at least the first three letters of a month name, matched
case-insensitively.  The remainder of the month name may appear but its
contents are irrelevant, so janissary, febrile, martial, apricot,
maybe, junta, etc. are happily handled.

Where the year is shown as optional, the current year is assumed.  There
are only two such cases, the form Jun 20 or 14 September (the only two
commonly occurring forms, apart from a "the" in some forms of English,
which isn't currently supported).  Such dates will of course become
ambiguous in the future, so should ideally be avoided.

Times may follow dates with a colon, e.g. 1965/07/12:09:45; this is in
order to provide a format with no whitespace.  A comma and whitespace
are allowed, e.g. 1965/07/12, 09:45.  Currently the order of these
separators is not checked, so illogical formats such as 1965/07/12, :
,09:45 will also be matched.  For simplicity such variations are not
shown in the list above.  Otherwise, a time is only recognised as being
associated with a date if there is only whitespace in between, or if the
time was embedded in the date.

Days of the week are not normally scanned, but will be ignored if they
occur at the start of the date pattern only.  However, in contexts
where it is useful to specify dates relative to today, days of the week
with no other date specification may be given.  The day is assumed to
be either today or within the past week.  Likewise, the words yesterday,
today and tomorrow are handled.  All matches are case-insensitive.
Hence if today is Monday, then Sunday is equivalent to yesterday,
Monday is equivalent to today, but Tuesday gives a date six days ago.
This is not generally useful within the calendar file.  Dates in this
format may be combined with a time specification; for example Tomorrow,
8 p.m..

For example, the standard date format:


     Fri Aug 18 17:00:48 BST 2006

is handled by matching HH:MM:SS and removing it together with the
matched (but unused) time zone.  This leaves the following:


     Fri Aug 18 2006

Fri is ignored and the rest is matched according to the standard rules.



23.2.3 Relative Time Format
---------------------------

In certain places relative times are handled.  Here, a date is not
allowed; instead a combination of various supported periods are
allowed, together with an optional time.  The periods must be in order
from most to least significant.

In some cases, a more accurate calculation is possible when there is an
anchor date:  offsets of months or years pick the correct day, rather
than being rounded, and it is possible to pick a particular day in a
month as `(1st Friday)', etc., as described in more detail below.

Anchors are available in the following cases.  If one or two times are
passed to the function calendar, the start time acts an anchor for the
end time when the end time is relative (even if the start time is
implicit).  When examining calendar files, the scheduled event being
examined anchors the warning time when it is given explicitly by means
of the WARN keyword; likewise, the scheduled event anchors a repetition
period when given by the RPT keyword, so that specifications such as
RPT 2 months, 3rd Thursday are handled properly.  Finally, the -R
argument to calendar_scandate directly provides an anchor for relative
calculations.

The periods handled, with possible abbreviations are:


Years
     years, yrs, ys, year, yr, y, yearly.  A year is 365.25 days unless
     there is an anchor.

Months
     months, mons, mnths, mths, month, mon, mnth, mth, monthly.  Note
     that m, ms, mn, mns are ambiguous and are _not_ handled.  A month
     is a period of 30 days rather than a calendar month unless there
     is an anchor.

Weeks
     weeks, wks, ws, week, wk, w, weekly

Days
     days, dys, ds, day, dy, d, daily

Hours
     hours, hrs, hs, hour, hr, h, hourly

Minutes
     minutes, mins, minute, min, but _not_ m, ms, mn or mns

Seconds
     seconds, secs, ss, second, sec, s


Spaces between the numbers are optional, but are required between items,
although a comma may be used (with or without spaces).

The forms yearly to hourly allow the number to be omitted; it is
assumed to be 1.  For example, 1 d and daily are equivalent.  Note that
using those forms with plurals is confusing; 2 yearly is the same as 2
years, _not_ twice yearly, so it is recommended they only be used
without numbers.

When an anchor time is present, there is an extension to handle regular
events in the form of the Nth SOMEday of the month.  Such a
specification must occur immediately after any year and month
specification, but before any time of day, and must be in the form
N(th|st|rd) DAY, for example 1st Tuesday or 3rd Monday.  As in other
places, days are matched case insensitively, must be in English, and
only the first three letters are significant except that a form
beginning `month' does not match `Monday'.  No attempt is made to
sanitize the resulting date; attempts to squeeze too many occurrences
into a month will push the day into the next month (but in the obvious
fashion, retaining the correct day of the week).

Here are some examples:


     30 years 3 months 4 days 3:42:41
     14 days 5 hours
     Monthly, 3rd Thursday
     4d,10hr


23.2.4 Example
--------------

Here is an example calendar file.  It uses a consistent date format, as
recommended above.


     Feb 1, 2006 14:30 Pointless bureaucratic meeting
     Mar 27, 2006 11:00 Mutual recrimination and finger pointing
       Bring water pistol and waterproofs
     Mar 31, 2006 14:00 Very serious managerial pontification
       # UID 12C7878A9A50
     Apr 10, 2006 13:30 Even more pointless blame assignment exercise WARN 30 mins
     May 18, 2006 16:00 Regular moaning session RPT monthly, 3rd Thursday

The second entry has a continuation line.  The third entry has a
continuation line that will not be shown when the entry is displayed,
but the unique identifier will be used by the calendar_add function when
updating the event.  The fourth entry will produce a warning 30 minutes
before the event (to allow you to equip yourself appropriately).  The
fifth entry repeats after a month on the 3rd Thursday, i.e. June 15,
2006, at the same time.