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zshexpn (1)

Name

zshexpn - zsh expansion and substitution

Synopsis

Please see following description for synopsis

Description

ZSHEXPN(1)                  General Commands Manual                 ZSHEXPN(1)



NAME
       zshexpn - zsh expansion and substitution

DESCRIPTION
       The  following types of expansions are performed in the indicated order
       in five steps:

       History Expansion
              This is performed only in interactive shells.

       Alias Expansion
              Aliases are expanded immediately  before  the  command  line  is
              parsed as explained under Aliasing in zshmisc(1).

       Process Substitution
       Parameter Expansion
       Command Substitution
       Arithmetic Expansion
       Brace Expansion
              These  five  are  performed  in  left-to-right fashion.  On each
              argument, any of the five steps that are  needed  are  performed
              one  after  the  other.   Hence,  for  example, all the parts of
              parameter expansion are completed before command substitution is
              started.   After  these  expansions, all unquoted occurrences of
              the characters `\',`'' and `"' are removed.

       Filename Expansion
              If the SH_FILE_EXPANSION option is set, the order  of  expansion
              is  modified  for  compatibility  with sh and ksh.  In that case
              filename expansion is performed immediately after  alias  expan-
              sion, preceding the set of five expansions mentioned above.

       Filename Generation
              This expansion, commonly referred to as globbing, is always done
              last.

       The following sections explain the types of expansion in detail.

HISTORY EXPANSION
       History expansion allows you to use words from previous  command  lines
       in  the  command line you are typing.  This simplifies spelling correc-
       tions and the repetition of complicated commands or arguments.

       Immediately before execution, each command  is  saved  in  the  history
       list,  the  size of which is controlled by the HISTSIZE parameter.  The
       one most recent command is always retained in  any  case.   Each  saved
       command in the history list is called a history event and is assigned a
       number, beginning with 1 (one) when the shell starts up.   The  history
       number  that  you  may  see  in  your  prompt  (see EXPANSION OF PROMPT
       SEQUENCES in zshmisc(1)) is the number that is to be  assigned  to  the
       next command.

   Overview
       A  history  expansion  begins with the first character of the histchars
       parameter, which is `!' by default, and may occur anywhere on the  com-
       mand line, including inside double quotes (but not inside single quotes
       '...' or C-style quotes $'...' nor when escaped with a backslash).

       The first character is followed by an optional  event  designator  (see
       the  section  `Event Designators') and then an optional word designator
       (the section `Word Designators'); if neither of  these  designators  is
       present, no history expansion occurs.

       Input  lines  containing  history  expansions  are  echoed  after being
       expanded, but before any other expansions take  place  and  before  the
       command  is executed.  It is this expanded form that is recorded as the
       history event for later references.

       History expansions do not nest.

       By default, a history reference with no event designator refers to  the
       same  event as any preceding history reference on that command line; if
       it is the only history reference in a command, it refers to the  previ-
       ous  command.   However,  if the option CSH_JUNKIE_HISTORY is set, then
       every history reference with no event specification  always  refers  to
       the previous command.

       For  example,  `!' is the event designator for the previous command, so
       `!!:1' always refers to the first word of  the  previous  command,  and
       `!!$'  always  refers  to  the last word of the previous command.  With
       CSH_JUNKIE_HISTORY set, then `!:1' and `!$' function in the same manner
       as  `!!:1'  and `!!$', respectively.  Conversely, if CSH_JUNKIE_HISTORY
       is unset, then `!:1' and `!$'  refer  to  the  first  and  last  words,
       respectively, of the same event referenced by the nearest other history
       reference preceding them on the current command line, or to the  previ-
       ous command if there is no preceding reference.

       The  character  sequence  `^foo^bar'  (where `^' is actually the second
       character of the histchars parameter) repeats the last command, replac-
       ing  the string foo with bar.  More precisely, the sequence `^foo^bar^'
       is synonymous with `!!:s^foo^bar^', hence other modifiers (see the sec-
       tion   `Modifiers')   may   follow   the  final  `^'.   In  particular,
       `^foo^bar^:G' performs a global substitution.

       If the shell encounters the character sequence `!"' in the  input,  the
       history  mechanism  is temporarily disabled until the current list (see
       zshmisc(1)) is fully parsed.  The `!"' is removed from the  input,  and
       any subsequent `!' characters have no special significance.

       A  less convenient but more comprehensible form of command history sup-
       port is provided by the fc builtin.

   Event Designators
       An event designator is a reference to a command-line entry in the  his-
       tory  list.   In  the list below, remember that the initial `!' in each
       item may be changed to  another  character  by  setting  the  histchars
       parameter.

       !      Start a history expansion, except when followed by a blank, new-
              line, `=' or `('.  If followed immediately by a word  designator
              (see  the section `Word Designators'), this forms a history ref-
              erence with no event designator (see the section `Overview').

       !!     Refer to  the  previous  command.   By  itself,  this  expansion
              repeats the previous command.

       !n     Refer to command-line n.

       !-n    Refer to the current command-line minus n.

       !str   Refer to the most recent command starting with str.

       !?str[?]
              Refer  to  the most recent command containing str.  The trailing
              `?' is necessary if this reference is to be followed by a  modi-
              fier  or  followed by any text that is not to be considered part
              of str.

       !#     Refer to the current command line typed in so far.  The line  is
              treated  as  if  it  were  complete up to and including the word
              before the one with the `!#' reference.

       !{...} Insulate a history reference from adjacent characters (if neces-
              sary).

   Word Designators
       A word designator indicates which word or words of a given command line
       are to be included in a history reference.  A `:' usually separates the
       event  specification  from the word designator.  It may be omitted only
       if the word designator begins with a `^', `$', `*', `-' or  `%'.   Word
       designators include:

       0      The first input word (command).
       n      The nth argument.
       ^      The first argument.  That is, 1.
       $      The last argument.
       %      The word matched by (the most recent) ?str search.
       x-y    A range of words; x defaults to 0.
       *      All the arguments, or a null value if there are none.
       x*     Abbreviates `x-$'.
       x-     Like `x*' but omitting word $.

       Note  that  a  `%' word designator works only when used in one of `!%',
       `!:%' or `!?str?:%', and only when used after a !? expansion  (possibly
       in  an  earlier  command).  Anything else results in an error, although
       the error may not be the most obvious one.

   Modifiers
       After the optional word designator, you can add a sequence  of  one  or
       more  of  the following modifiers, each preceded by a `:'.  These modi-
       fiers also work on the result  of  filename  generation  and  parameter
       expansion, except where noted.

       a      Turn  a  file  name into an absolute path:  prepends the current
              directory, if necessary; remove `.' path  segments;  and  remove
              `..'  path  segments  and  the segments that immediately precede
              them.

              This transformation is agnostic about what is in the filesystem,
              i.e.  is  on  the logical, not the physical directory.  It takes
              place in the same manner as when changing directories when  nei-
              ther of the options CHASE_DOTS or CHASE_LINKS is set.  For exam-
              ple,   `/before/here/../after'   is   always   transformed    to
              `/before/after',  regardless of whether `/before/here' exists or
              what kind of object (dir, file, symlink, etc.) it is.

       A      Turn a file name into an absolute path as the `a' modifier does,
              and  then  pass the result through the realpath(3) library func-
              tion to resolve symbolic links.

              Note: on systems that do not have a  realpath(3)  library  func-
              tion,  symbolic  links are not resolved, so on those systems `a'
              and `A' are equivalent.

              Note: foo:A and realpath(foo) are different on some inputs.  For
              realpath(foo) semantics, see the `P` modifier.

       c      Resolve  a  command  name into an absolute path by searching the
              command path given by the PATH variable.  This does not work for
              commands  containing  directory parts.  Note also that this does
              not usually work as a glob qualifier unless a file of  the  same
              name is found in the current directory.

       e      Remove  all but the part of the filename extension following the
              `.'; see  the  definition  of  the  filename  extension  in  the
              description  of  the  r  modifier below.  Note that according to
              that definition the result will be empty if the string ends with
              a `.'.

       h      Remove  a  trailing  pathname component, leaving the head.  This
              works like `dirname'.

       l      Convert the words to all lowercase.

       p      Print the new command but do not execute it.   Only  works  with
              history expansion.

       P      Turn  a  file name into an absolute path, like realpath(3).  The
              resulting path will be absolute, have neither `.' nor `..'  com-
              ponents,  and  refer  to  the  same directory entry as the input
              filename.

              Unlike realpath(3), non-existent trailing components are permit-
              ted and preserved.

       q      Quote  the  substituted  words,  escaping further substitutions.
              Works with history expansion and parameter expansion, though for
              parameters  it  is  only  useful  if the resulting text is to be
              re-evaluated such as by eval.

       Q      Remove one level of quotes from the substituted words.

       r      Remove a filename extension leaving the root name.  Strings with
              no  filename extension are not altered.  A filename extension is
              a `.' followed by any number of characters (including zero) that
              are  neither  `.'  nor  `/'  and that continue to the end of the
              string.  For example, the extension of `foo.orig.c' is `.c', and
              `dir.c/foo' has no extension.

       s/l/r[/]
              Substitute r for l as described below.  The substitution is done
              only for the first string that matches l.  For  arrays  and  for
              filename  generation,  this applies to each word of the expanded
              text.  See below for further notes on substitutions.

              The forms `gs/l/r' and `s/l/r/:G' perform  global  substitution,
              i.e. substitute every occurrence of r for l.  Note that the g or
              :G must appear in exactly the position shown.

              See further notes on this form of substitution below.

       &      Repeat the previous s substitution.  Like  s,  may  be  preceded
              immediately  by  a  g.  In parameter expansion the & must appear
              inside braces, and in filename generation it must be quoted with
              a backslash.

       t      Remove  all leading pathname components, leaving the tail.  This
              works like `basename'.

       u      Convert the words to all uppercase.

       x      Like q, but break into words at whitespace.  Does not work  with
              parameter expansion.

       The  s/l/r/  substitution  works  as follows.  By default the left-hand
       side of substitutions are not patterns,  but  character  strings.   Any
       character  can  be  used as the delimiter in place of `/'.  A backslash
       quotes  the  delimiter  character.    The   character   `&',   in   the
       right-hand-side  r,  is replaced by the text from the left-hand-side l.
       The `&' can be quoted with a backslash.  A null  l  uses  the  previous
       string  either from the previous l or from the contextual scan string s
       from `!?s'.  You can omit the rightmost delimiter if a newline  immedi-
       ately  follows  r; the rightmost `?' in a context scan can similarly be
       omitted.  Note the same record of the last l and r is maintained across
       all forms of expansion.

       Note that if a `&' is used within glob qualifiers an extra backslash is
       needed as a & is a special character in this case.

       Also note that the order of expansions affects the interpretation of  l
       and r.  When used in a history expansion, which occurs before any other
       expansions, l and r are treated as literal strings (except as explained
       for  HIST_SUBST_PATTERN  below).  When used in parameter expansion, the
       replacement of r into the parameter's value is done first, and then any
       additional process, parameter, command, arithmetic, or brace references
       are applied, which may evaluate those substitutions and expansions more
       than once if l appears more than once in the starting value.  When used
       in a glob qualifier, any substitutions or expansions are performed once
       at  the  time  the qualifier is parsed, even before the `:s' expression
       itself is divided into l and r sides.

       If the option HIST_SUBST_PATTERN is set, l is treated as a  pattern  of
       the  usual  form  described  in  the section FILENAME GENERATION below.
       This can be used in all the places where modifiers are available; note,
       however, that in globbing qualifiers parameter substitution has already
       taken place, so parameters in the replacement string should  be  quoted
       to  ensure  they are replaced at the correct time.  Note also that com-
       plicated patterns used in globbing qualifiers  may  need  the  extended
       glob  qualifier notation (#q:s/.../.../) in order for the shell to rec-
       ognize the expression as a glob qualifier.  Further, note that bad pat-
       terns  in the substitution are not subject to the NO_BAD_PATTERN option
       so will cause an error.

       When HIST_SUBST_PATTERN is set, l may start with a # to  indicate  that
       the  pattern  must  match at the start of the string to be substituted,
       and a % may appear at the start or after an # to indicate that the pat-
       tern must match at the end of the string to be substituted.  The % or #
       may be quoted with two backslashes.

       For example, the following piece of filename generation code  with  the
       EXTENDED_GLOB option:

              print *.c(#q:s/#%(#b)s(*).c/'S${match[1]}.C'/)

       takes  the  expansion  of  *.c  and  applies the glob qualifiers in the
       (#q...) expression, which consists of a substitution modifier  anchored
       to  the  start and end of each word (#%).  This turns on backreferences
       ((#b)), so that the parenthesised subexpression  is  available  in  the
       replacement string as ${match[1]}.  The replacement string is quoted so
       that the parameter is not substituted before the start of filename gen-
       eration.

       The  following  f, F, w and W modifiers work only with parameter expan-
       sion and filename generation.  They are listed here to provide a single
       point of reference for all modifiers.

       f      Repeats  the  immediately  (without  a colon) following modifier
              until the resulting word doesn't change any more.

       F:expr:
              Like f, but repeats only n times if the expression  expr  evalu-
              ates  to  n.   Any  character can be used instead of the `:'; if
              `(', `[', or `{' is used as the opening delimiter,  the  closing
              delimiter should be ')', `]', or `}', respectively.

       w      Makes  the  immediately  following modifier work on each word in
              the string.

       W:sep: Like w but words are considered to be the parts  of  the  string
              that  are separated by sep. Any character can be used instead of
              the `:'; opening parentheses are handled specially, see above.

PROCESS SUBSTITUTION
       Each part  of  a  command  argument  that  takes  the  form  `<(list)',
       `>(list)' or `=(list)' is subject to process substitution.  The expres-
       sion may be preceded or followed by other strings except that, to  pre-
       vent  clashes  with  commonly  occurring strings and patterns, the last
       form must occur at the start of a command argument, and the  forms  are
       only  expanded  when  first  parsing  command  or assignment arguments.
       Process substitutions may be used following redirection  operators;  in
       this case, the substitution must appear with no trailing string.

       Note  that  `<<(list)'  is not a special syntax; it is equivalent to `<
       <(list)', redirecting standard input from the result of process substi-
       tution.   Hence  all  the  following documentation applies.  The second
       form (with the space) is recommended for clarity.

       In the case of the < or > forms, the shell runs the commands in list as
       a  subprocess of the job executing the shell command line.  If the sys-
       tem supports the /dev/fd mechanism, the command argument is the name of
       the  device  file corresponding to a file descriptor; otherwise, if the
       system supports named pipes (FIFOs), the command  argument  will  be  a
       named  pipe.   If the form with > is selected then writing on this spe-
       cial file will provide input for list.  If < is  used,  then  the  file
       passed  as  an  argument  will  be  connected to the output of the list
       process.  For example,

              paste <(cut -f1 file1) <(cut -f3 file2) |
              tee >(process1) >(process2) >/dev/null

       cuts fields 1 and 3 from the files file1 and file2 respectively, pastes
       the  results  together,  and  sends  it  to  the processes process1 and
       process2.

       If =(...) is used instead of <(...), then the file passed as  an  argu-
       ment  will be the name of a temporary file containing the output of the
       list process.  This may be used instead of the <  form  for  a  program
       that expects to lseek (see lseek(2)) on the input file.

       There is an optimisation for substitutions of the form =(<<<arg), where
       arg is a single-word argument to the here-string redirection <<<.  This
       form produces a file name containing the value of arg after any substi-
       tutions have been performed.  This is handled entirely within the  cur-
       rent  shell.   This  is  effectively  the  reverse  of the special form
       $(<arg) which treats arg as a file name and replaces it with the file's
       contents.

       The = form is useful as both the /dev/fd and the named pipe implementa-
       tion of <(...) have drawbacks.  In the former case, some programmes may
       automatically  close  the  file descriptor in question before examining
       the file on the command line, particularly if  this  is  necessary  for
       security  reasons such as when the programme is running setuid.  In the
       second case, if the programme does not actually open the file, the sub-
       shell  attempting  to read from or write to the pipe will (in a typical
       implementation, different operating systems may have  different  behav-
       iour)  block for ever and have to be killed explicitly.  In both cases,
       the shell actually supplies the information using a pipe, so that  pro-
       grammes that expect to lseek (see lseek(2)) on the file will not work.

       Also  note  that  the  previous example can be more compactly and effi-
       ciently written (provided the MULTIOS option is set) as:

              paste <(cut -f1 file1) <(cut -f3 file2) \
              > >(process1) > >(process2)

       The shell uses pipes instead of  FIFOs  to  implement  the  latter  two
       process substitutions in the above example.

       There  is  an additional problem with >(process); when this is attached
       to an external command, the parent shell does not wait for  process  to
       finish  and  hence  an immediately following command cannot rely on the
       results being complete.  The problem  and  solution  are  the  same  as
       described  in the section MULTIOS in zshmisc(1).  Hence in a simplified
       version of the example above:

              paste <(cut -f1 file1) <(cut -f3 file2) > >(process)

       (note that no MULTIOS are involved), process will be run asynchronously
       as far as the parent shell is concerned.  The workaround is:

              { paste <(cut -f1 file1) <(cut -f3 file2) } > >(process)

       The  extra  processes here are spawned from the parent shell which will
       wait for their completion.

       Another problem arises any time a job with a substitution that requires
       a  temporary  file  is  disowned by the shell, including the case where
       `&!' or `&|' appears at the end of a command containing a substitution.
       In  that case the temporary file will not be cleaned up as the shell no
       longer has any memory of the job.  A workaround is to use  a  subshell,
       for example,

              (mycmd =(myoutput)) &!

       as  the forked subshell will wait for the command to finish then remove
       the temporary file.

       A general workaround to ensure a process substitution  endures  for  an
       appropriate length of time is to pass it as a parameter to an anonymous
       shell function (a piece of shell code  that  is  run  immediately  with
       function scope).  For example, this code:

              () {
                 print File $1:
                 cat $1
              } =(print This be the verse)

       outputs something resembling the following

              File /tmp/zsh6nU0kS:
              This be the verse

       The  temporary file created by the process substitution will be deleted
       when the function exits.

PARAMETER EXPANSION
       The character `$' is used to introduce parameter expansions.  See  zsh-
       param(1) for a description of parameters, including arrays, associative
       arrays, and subscript notation to access individual array elements.

       Note in particular the fact that words of unquoted parameters  are  not
       automatically  split  on  whitespace unless the option SH_WORD_SPLIT is
       set; see references to this option below for more details.  This is  an
       important difference from other shells.

       In  the  expansions discussed below that require a pattern, the form of
       the pattern is the same as that used for filename generation;  see  the
       section  `Filename  Generation'.   Note that these patterns, along with
       the replacement text of any substitutions, are  themselves  subject  to
       parameter  expansion,  command  substitution, and arithmetic expansion.
       In addition to the following operations, the colon modifiers  described
       in  the  section  `Modifiers' in the section `History Expansion' can be
       applied:  for example, ${i:s/foo/bar/} performs string substitution  on
       the expansion of parameter $i.

       In  the  following descriptions, `word' refers to a single word substi-
       tuted on the command line, not  necessarily  a  space  delimited  word.
       With default options, after the assignments:

              array=("first word" "second word")
              scalar="only word"

       then  $array substitutes two words, `first word' and `second word', and
       $scalar substitutes a single word `only word'.  This may be modified by
       explicit  or implicit word-splitting, however.  The full rules are com-
       plicated and are noted at the end.

       ${name}
              The value, if any, of the parameter name  is  substituted.   The
              braces are required if the expansion is to be followed by a let-
              ter, digit, or underscore that is not to be interpreted as  part
              of  name.   In  addition, more complicated forms of substitution
              usually require the braces to be present; exceptions, which only
              apply  if  the  option  KSH_ARRAYS is not set, are a single sub-
              script or any colon modifiers appearing after the name,  or  any
              of the characters `^', `=', `~', `#' or `+' appearing before the
              name, all of which work with or without braces.

              If name is an array parameter, and the KSH_ARRAYS option is  not
              set,  then the value of each element of name is substituted, one
              element per word.  Otherwise, the expansion results in one  word
              only;  with  KSH_ARRAYS,  this is the first element of an array.
              No  field  splitting  is  done  on   the   result   unless   the
              SH_WORD_SPLIT   option  is  set.   See  also  the  flags  =  and
              s:string:.

       ${+name}
              If name is the name of a set parameter `1' is substituted,  oth-
              erwise `0' is substituted.

       ${name-word}
       ${name:-word}
              If  name is set, or in the second form is non-null, then substi-
              tute its value; otherwise substitute word.  In the  second  form
              name may be omitted, in which case word is always substituted.

       ${name+word}
       ${name:+word}
              If  name is set, or in the second form is non-null, then substi-
              tute word; otherwise substitute nothing.

       ${name=word}
       ${name:=word}
       ${name::=word}
              In the first form, if name is unset then set it to word; in  the
              second  form,  if name is unset or null then set it to word; and
              in the third form, unconditionally set name  to  word.   In  all
              forms, the value of the parameter is then substituted.

       ${name?word}
       ${name:?word}
              In the first form, if name is set, or in the second form if name
              is both set and non-null, then substitute its value;  otherwise,
              print  word and exit from the shell.  Interactive shells instead
              return to the prompt.  If word is omitted, then a standard  mes-
              sage is printed.

       In  any of the above expressions that test a variable and substitute an
       alternate word, note that you can use standard  shell  quoting  in  the
       word   value   to  selectively  override  the  splitting  done  by  the
       SH_WORD_SPLIT option and the = flag, but not splitting by the s:string:
       flag.

       In  the  following expressions, when name is an array and the substitu-
       tion is not quoted, or if the `(@)' flag or the name[@] syntax is used,
       matching and replacement is performed on each array element separately.

       ${name#pattern}
       ${name##pattern}
              If  the pattern matches the beginning of the value of name, then
              substitute the value of name with the matched  portion  deleted;
              otherwise,  just  substitute  the  value  of name.  In the first
              form, the smallest matching pattern is preferred; in the  second
              form, the largest matching pattern is preferred.

       ${name%pattern}
       ${name%%pattern}
              If  the  pattern matches the end of the value of name, then sub-
              stitute the value of name with the matched portion deleted; oth-
              erwise,  just  substitute the value of name.  In the first form,
              the smallest matching pattern is preferred; in the second  form,
              the largest matching pattern is preferred.

       ${name:#pattern}
              If  the  pattern  matches the value of name, then substitute the
              empty string; otherwise, just substitute the value of name.   If
              name  is  an  array the matching array elements are removed (use
              the `(M)' flag to remove the non-matched elements).

       ${name:|arrayname}
              If arrayname is the name (N.B., not contents) of an array  vari-
              able,  then any elements contained in arrayname are removed from
              the substitution of name.  If the substitution is scalar, either
              because  name  is a scalar variable or the expression is quoted,
              the elements of arrayname are instead tested against the  entire
              expression.

       ${name:*arrayname}
              Similar  to  the  preceding  substitution,  but  in the opposite
              sense, so that entries present in both the original substitution
              and as elements of arrayname are retained and others removed.

       ${name:^arrayname}
       ${name:^^arrayname}
              Zips  two arrays, such that the output array is twice as long as
              the shortest (longest for `:^^') of name and arrayname, with the
              elements  alternatingly being picked from them. For `:^', if one
              of the input arrays is longer, the output will stop when the end
              of the shorter array is reached.  Thus,

                     a=(1 2 3 4); b=(a b); print ${a:^b}

              will  output  `1  a 2 b'.  For `:^^', then the input is repeated
              until all of the longer array has been used  up  and  the  above
              will output `1 a 2 b 3 a 4 b'.

              Either  or  both inputs may be a scalar, they will be treated as
              an array of length 1 with the scalar as  the  only  element.  If
              either  array  is empty, the other array is output with no extra
              elements inserted.

              Currently the following code will output `a b' and  `1'  as  two
              separate  elements,  which  can  be unexpected. The second print
              provides a workaround which should continue to work if  this  is
              changed.

                     a=(a b); b=(1 2); print -l "${a:^b}"; print -l "${${a:^b}}"

       ${name:offset}
       ${name:offset:length}
              This  syntax  gives effects similar to parameter subscripting in
              the form $name[start,end], but is compatible with other  shells;
              note  that  both  offset  and length are interpreted differently
              from the components of a subscript.

              If offset is non-negative, then if the variable name is a scalar
              substitute  the  contents  starting  offset  characters from the
              first character of the string, and if name is an  array  substi-
              tute  elements  starting offset elements from the first element.
              If length is given, substitute that many characters or elements,
              otherwise the entire rest of the scalar or array.

              A positive offset is always treated as the offset of a character
              or element in name from the first character or  element  of  the
              array  (this  is  different from native zsh subscript notation).
              Hence 0 refers to the first character or element  regardless  of
              the setting of the option KSH_ARRAYS.

              A negative offset counts backwards from the end of the scalar or
              array, so that -1 corresponds to the last character or  element,
              and so on.

              When positive, length counts from the offset position toward the
              end of the scalar or array.  When negative, length  counts  back
              from  the  end.  If this results in a position smaller than off-
              set, a diagnostic is printed and nothing is substituted.

              The option MULTIBYTE is obeyed, i.e. the offset and length count
              multibyte characters where appropriate.

              offset and length undergo the same set of shell substitutions as
              for scalar assignment; in addition, they  are  then  subject  to
              arithmetic evaluation.  Hence, for example

                     print ${foo:3}
                     print ${foo: 1 + 2}
                     print ${foo:$(( 1 + 2))}
                     print ${foo:$(echo 1 + 2)}

              all  have the same effect, extracting the string starting at the
              fourth character of $foo if  the  substitution  would  otherwise
              return  a scalar, or the array starting at the fourth element if
              $foo  would  return  an  array.   Note  that  with  the   option
              KSH_ARRAYS  $foo  always returns a scalar (regardless of the use
              of the offset syntax) and a form such as ${foo[*]:3} is required
              to extract elements of an array named foo.

              If  offset  is  negative, the - may not appear immediately after
              the : as this indicates the ${name:-word} form of  substitution.
              Instead,  a  space  may  be inserted before the -.  Furthermore,
              neither offset nor length may begin with an alphabetic character
              or  & as these are used to indicate history-style modifiers.  To
              substitute a value from a variable, the recommended approach  is
              to  precede it with a $ as this signifies the intention (parame-
              ter substitution can easily be rendered unreadable); however, as
              arithmetic  substitution  is  performed,  the  expression ${var:
              offs} does work, retrieving the offset from $offs.

              For further compatibility with other shells there is  a  special
              case  for  array offset 0.  This usually accesses the first ele-
              ment of the array.  However, if the substitution refers  to  the
              positional parameter array, e.g. $@ or $*, then offset 0 instead
              refers to $0, offset 1 refers to $1, and so on.  In other words,
              the  positional  parameter  array  is  effectively  extended  by
              prepending $0.  Hence ${*:0:1} substitutes $0 and ${*:1:1}  sub-
              stitutes $1.

       ${name/pattern/repl}
       ${name//pattern/repl}
       ${name:/pattern/repl}
              Replace  the  longest possible match of pattern in the expansion
              of parameter name by string repl.  The first form replaces  just
              the  first  occurrence, the second form all occurrences, and the
              third form replaces only if pattern matches the  entire  string.
              Both pattern and repl are subject to double-quoted substitution,
              so that expressions like ${name/$opat/$npat} will work, but obey
              the  usual rule that pattern characters in $opat are not treated
              specially unless either the option GLOB_SUBST is set,  or  $opat
              is instead substituted as ${~opat}.

              The pattern may begin with a `#', in which case the pattern must
              match at the start of the string, or `%', in which case it  must
              match  at  the end of the string, or `#%' in which case the pat-
              tern must match the entire string.  The repl  may  be  an  empty
              string,  in  which  case  the final `/' may also be omitted.  To
              quote the final `/' in other cases it should be  preceded  by  a
              single backslash; this is not necessary if the `/' occurs inside
              a substituted parameter.  Note also that the `#',  `%'  and  `#%
              are  not  active  if  they occur inside a substituted parameter,
              even at the start.

              If, after quoting rules apply, ${name} expands to an array,  the
              replacements  act  on  each element individually.  Note also the
              effect of the I and S parameter expansion flags below;  however,
              the flags M, R, B, E and N are not useful.

              For example,

                     foo="twinkle twinkle little star" sub="t*e" rep="spy"
                     print ${foo//${~sub}/$rep}
                     print ${(S)foo//${~sub}/$rep}

              Here, the `~' ensures that the text of $sub is treated as a pat-
              tern rather than a plain string.  In the first case, the longest
              match for t*e is substituted and the result is `spy star', while
              in the second case, the  shortest  matches  are  taken  and  the
              result is `spy spy lispy star'.

       ${#spec}
              If spec is one of the above substitutions, substitute the length
              in characters of the result instead of the  result  itself.   If
              spec  is  an array expression, substitute the number of elements
              of the result.  This has the side-effect that joining is skipped
              even  in quoted forms, which may affect other sub-expressions in
              spec.  Note that `^', `=', and `~', below, must  appear  to  the
              left of `#' when these forms are combined.

              If the option POSIX_IDENTIFIERS is not set, and spec is a simple
              name, then the braces are optional; this is true even  for  spe-
              cial  parameters  so  e.g.  $#-  and  $#* take the length of the
              string $- and the array $* respectively.   If  POSIX_IDENTIFIERS
              is set, then braces are required for the # to be treated in this
              fashion.

       ${^spec}
              Turn on the RC_EXPAND_PARAM option for the evaluation  of  spec;
              if  the  `^'  is doubled, turn it off.  When this option is set,
              array expansions of the form foo${xx}bar, where the parameter xx
              is  set  to  (a  b  c),  are  substituted  with `fooabar foobbar
              foocbar' instead of the default `fooa b  cbar'.   Note  that  an
              empty array will therefore cause all arguments to be removed.

              Internally, each such expansion is converted into the equivalent
              list   for   brace    expansion.     E.g.,    ${^var}    becomes
              {$var[1],$var[2],...}, and is processed as described in the sec-
              tion `Brace Expansion' below: note, however, the expansion  hap-
              pens  immediately,  with  any explicit brace expansion happening
              later.  If word splitting is also  in  effect  the  $var[N]  may
              themselves be split into different list elements.

       ${=spec}
              Perform  word splitting using the rules for SH_WORD_SPLIT during
              the evaluation of spec, but regardless of whether the  parameter
              appears  in  double  quotes; if the `=' is doubled, turn it off.
              This forces parameter expansions to be split into separate words
              before  substitution, using IFS as a delimiter.  This is done by
              default in most other shells.

              Note that splitting is applied to word in the  assignment  forms
              of  spec  before  the  assignment  to  name  is performed.  This
              affects the result of array assignments with the A flag.

       ${~spec}
              Turn on the GLOB_SUBST option for the evaluation of spec; if the
              `~'  is  doubled,  turn  it  off.   When this option is set, the
              string resulting from the expansion will  be  interpreted  as  a
              pattern anywhere that is possible, such as in filename expansion
              and filename generation and pattern-matching contexts  like  the
              right hand side of the `=' and `!=' operators in conditions.

              In  nested  substitutions, note that the effect of the ~ applies
              to the result of the current level of substitution.  A surround-
              ing  pattern  operation on the result may cancel it.  Hence, for
              example, if the parameter foo is set to  *,  ${~foo//\*/*.c}  is
              substituted  by  the pattern *.c, which may be expanded by file-
              name  generation,  but  ${${~foo}//\*/*.c}  substitutes  to  the
              string *.c, which will not be further expanded.

       If  a ${...} type parameter expression or a $(...) type command substi-
       tution is used in place of name above, it is  expanded  first  and  the
       result is used as if it were the value of name.  Thus it is possible to
       perform nested operations:  ${${foo#head}%tail} substitutes  the  value
       of  $foo  with both `head' and `tail' deleted.  The form with $(...) is
       often useful in combination with the  flags  described  next;  see  the
       examples  below.   Each  name or nested ${...} in a parameter expansion
       may also be followed by a subscript expression as  described  in  Array
       Parameters in zshparam(1).

       Note  that double quotes may appear around nested expressions, in which
       case  only  the  part  inside  is  treated  as  quoted;  for   example,
       ${(f)"$(foo)"}  quotes  the  result  of $(foo), but the flag `(f)' (see
       below) is applied using the rules for unquoted expansions.   Note  fur-
       ther that quotes are themselves nested in this context; for example, in
       "${(@f)"$(foo)"}", there are two sets of quotes,  one  surrounding  the
       whole  expression,  the  other  (redundant)  surrounding  the $(foo) as
       before.

   Parameter Expansion Flags
       If the opening brace is directly followed by  an  opening  parenthesis,
       the  string  up  to the matching closing parenthesis will be taken as a
       list of flags.  In cases where repeating a flag is meaningful, the rep-
       etitions need not be consecutive; for example, `(q%q%q)' means the same
       thing as the more readable `(%%qqq)'.  The  following  flags  are  sup-
       ported:

       #      Evaluate  the  resulting words as numeric expressions and output
              the characters corresponding to  the  resulting  integer.   Note
              that  this  form  is entirely distinct from use of the # without
              parentheses.

              If the MULTIBYTE option is set and the number  is  greater  than
              127  (i.e.  not  an  ASCII character) it is treated as a Unicode
              character.

       %      Expand all % escapes in the resulting words in the same  way  as
              in prompts (see EXPANSION OF PROMPT SEQUENCES in zshmisc(1)). If
              this flag is given twice, full prompt expansion is done  on  the
              resulting words, depending on the setting of the PROMPT_PERCENT,
              PROMPT_SUBST and PROMPT_BANG options.

       @      In double quotes, array elements are put  into  separate  words.
              E.g.,   `"${(@)foo}"'   is   equivalent   to  `"${foo[@]}"'  and
              `"${(@)foo[1,2]}"' is the same as `"$foo[1]"  "$foo[2]"'.   This
              is  distinct  from field splitting by the f, s or z flags, which
              still applies within each array element.

       A      Convert the substitution into an array expression,  even  if  it
              otherwise  would be scalar.  This has lower precedence than sub-
              scripting, so one level of nested expansion is required in order
              that  subscripts apply to array elements.  Thus ${${(A)name}[1]}
              yields the full value of name when name is scalar.

              This assigns an array parameter with `${...=...}', `${...:=...}'
              or  `${...::=...}'.   If  this  flag  is  repeated (as in `AA'),
              assigns an associative  array  parameter.   Assignment  is  made
              before  sorting  or  padding;  if field splitting is active, the
              word part is split before assignment.  The name part  may  be  a
              subscripted  range  for ordinary arrays; when assigning an asso-
              ciative array, the word part must be converted to an array,  for
              example by using `${(AA)=name=...}' to activate field splitting.

              Surrounding  context  such  as  additional nesting or use of the
              value in a scalar assignment may cause the array  to  be  joined
              back into a single string again.

       a      Sort  in  array  index  order;  when  combined  with `O' sort in
              reverse array index order.  Note that `a' is  therefore  equiva-
              lent  to the default but `Oa' is useful for obtaining an array's
              elements in reverse order.

       b      Quote with backslashes only characters that are special to  pat-
              tern  matching. This is useful when the contents of the variable
              are to be tested using GLOB_SUBST, including the ${~...} switch.

              Quoting using one of the q family of flags  does  not  work  for
              this  purpose  since  quotes  are  not stripped from non-pattern
              characters by GLOB_SUBST.  In other words,

                     pattern=${(q)str}
                     [[ $str = ${~pattern} ]]

              works if $str is `a*b' but not if it is `a b', whereas

                     pattern=${(b)str}
                     [[ $str = ${~pattern} ]]

              is always true for any possible value of $str.

       c      With ${#name}, count the total number of characters in an array,
              as  if  the elements were concatenated with spaces between them.
              This is not a true join of the array, so other expressions  used
              with  this  flag may have an effect on the elements of the array
              before it is counted.

       C      Capitalize the resulting words.  `Words' in this case refers  to
              sequences  of  alphanumeric characters separated by non-alphanu-
              merics, not to words that result from field splitting.

       D      Assume the string or  array  elements  contain  directories  and
              attempt  to  substitute the leading part of these by names.  The
              remainder of the path (the whole of it if the leading  part  was
              not  substituted) is then quoted so that the whole string can be
              used as a shell argument.  This is the reverse of `~'  substitu-
              tion:  see the section FILENAME EXPANSION below.

       e      Perform  single  word  shell expansions, namely parameter expan-
              sion, command substitution  and  arithmetic  expansion,  on  the
              result. Such expansions can be nested but too deep recursion may
              have unpredictable effects.

       f      Split the result of the expansion at newlines. This is a  short-
              hand for `ps:\n:'.

       F      Join  the words of arrays together using newline as a separator.
              This is a shorthand for `pj:\n:'.

       g:opts:
              Process escape sequences like the echo builtin when  no  options
              are  given (g::).  With the o option, octal escapes don't take a
              leading zero.  With the c option, sequences like `^X'  are  also
              processed.   With  the  e  option,  processes `\M-t' and similar
              sequences like the print builtin.  With both  of  the  o  and  e
              options,  behaves  like the print builtin except that in none of
              these modes is `\c' interpreted.

       i      Sort case-insensitively.  May be combined with `n' or `O'.

       k      If name refers to an  associative  array,  substitute  the  keys
              (element  names)  rather  than the values of the elements.  Used
              with subscripts (including ordinary arrays),  force  indices  or
              keys to be substituted even if the subscript form refers to val-
              ues.  However, this flag may  not  be  combined  with  subscript
              ranges.   With  the KSH_ARRAYS option a subscript `[*]' or `[@]'
              is needed to operate on the whole array, as usual.

       L      Convert all letters in the result to lower case.

       n      Sort decimal integers numerically; if the first differing  char-
              acters  of  two test strings are not digits, sorting is lexical.
              Integers with more initial zeroes are sorted before  those  with
              fewer  or  none.   Hence  the  array `foo1 foo02 foo2 foo3 foo20
              foo23' is sorted into the order shown.  May be combined with `i'
              or `O'.

       o      Sort  the resulting words in ascending order; if this appears on
              its own the sorting is lexical and  case-sensitive  (unless  the
              locale renders it case-insensitive).  Sorting in ascending order
              is the default for other forms of sorting, so this is ignored if
              combined with `a', `i' or `n'.

       O      Sort  the  resulting words in descending order; `O' without `a',
              `i' or `n' sorts in reverse lexical order.  May be combined with
              `a', `i' or `n' to reverse the order of sorting.

       P      This forces the value of the parameter name to be interpreted as
              a further parameter name, whose value will be used where  appro-
              priate.   Note  that flags set with one of the typeset family of
              commands (in particular case transformations) are not applied to
              the value of name used in this fashion.

              If  used  with  a  nested parameter or command substitution, the
              result of that will be taken as a parameter  name  in  the  same
              way.   For  example,  if  you  have `foo=bar' and `bar=baz', the
              strings ${(P)foo}, ${(P)${foo}}, and ${(P)$(echo bar)}  will  be
              expanded to `baz'.

              Likewise, if the reference is itself nested, the expression with
              the flag is treated as if  it  were  directly  replaced  by  the
              parameter name.  It is an error if this nested substitution pro-
              duces an array  with  more  than  one  word.   For  example,  if
              `name=assoc'  where the parameter assoc is an associative array,
              then `${${(P)name}[elt]}' refers to the element of the  associa-
              tive subscripted `elt'.

       q      Quote  characters that are special to the shell in the resulting
              words with backslashes; unprintable or  invalid  characters  are
              quoted  using  the  $'\NNN'  form, with separate quotes for each
              octet.

              If this flag is given twice, the resulting words are  quoted  in
              single  quotes  and  if  it  is given three times, the words are
              quoted in double quotes; in these forms no special  handling  of
              unprintable  or invalid characters is attempted.  If the flag is
              given four times, the words are quoted in single quotes preceded
              by  a  $.  Note that in all three of these forms quoting is done
              unconditionally, even if  this  does  not  change  the  way  the
              resulting string would be interpreted by the shell.

              If a q- is given (only a single q may appear), a minimal form of
              single quoting is used that only quotes the string if needed  to
              protect  special characters.  Typically this form gives the most
              readable output.

              If a q+ is given, an extended form of  minmal  quoting  is  used
              that  causes unprintable characters to be rendered using $'...'.
              This quoting is similar to that used by the output of values  by
              the typeset family of commands.

       Q      Remove one level of quotes from the resulting words.

       t      Use  a  string  describing  the  type of the parameter where the
              value of the parameter would usually appear.  This  string  con-
              sists  of keywords separated by hyphens (`-'). The first keyword
              in the string  describes  the  main  type,  it  can  be  one  of
              `scalar',  `array',  `integer',  `float'  or  `association'. The
              other keywords describe the type in more detail:

              local  for local parameters

              left   for left justified parameters

              right_blanks
                     for right justified parameters with leading blanks

              right_zeros
                     for right justified parameters with leading zeros

              lower  for parameters whose value is converted to all lower case
                     when it is expanded

              upper  for parameters whose value is converted to all upper case
                     when it is expanded

              readonly
                     for readonly parameters

              tag    for tagged parameters

              export for exported parameters

              unique for arrays which keep only the first occurrence of dupli-
                     cated values

              hide   for parameters with the `hide' flag

              hideval
                     for parameters with the `hideval' flag

              special
                     for special parameters defined by the shell

       u      Expand only the first occurrence of each unique word.

       U      Convert all letters in the result to upper case.

       v      Used  with k, substitute (as two consecutive words) both the key
              and the value of each associative array element.  Used with sub-
              scripts,  force  values  to be substituted even if the subscript
              form refers to indices or keys.

       V      Make any special characters in the resulting words visible.

       w      With ${#name}, count words in arrays or strings; the s flag  may
              be used to set a word delimiter.

       W      Similar  to  w  with  the  difference  that  empty words between
              repeated delimiters are also counted.

       X      With this flag, parsing errors occurring with the  Q,  e  and  #
              flags  or  the  pattern matching forms such as `${name#pattern}'
              are reported.  Without the flag, errors are silently ignored.

       z      Split the result of the expansion into words using shell parsing
              to  find  the words, i.e. taking into account any quoting in the
              value.  Comments are  not  treated  specially  but  as  ordinary
              strings, similar to interactive shells with the INTERACTIVE_COM-
              MENTS option unset (however, see the Z flag  below  for  related
              options)

              Note  that  this  is  done  very late, even later than the `(s)'
              flag. So to access single words in the result use nested  expan-
              sions as in `${${(z)foo}[2]}'. Likewise, to remove the quotes in
              the resulting words use `${(Q)${(z)foo}}'.

       0      Split the result of the expansion on  null  bytes.   This  is  a
              shorthand for `ps:\0:'.

       The following flags (except p) are followed by one or more arguments as
       shown.  Any character, or the matching pairs `(...)', `{...}', `[...]',
       or  `<...>',  may  be  used in place of a colon as delimiters, but note
       that when a flag takes more than one argument, a matched pair of delim-
       iters must surround each argument.

       p      Recognize  the  same  escape  sequences  as the print builtin in
              string arguments to any of the flags described below that follow
              this argument.

              Alternatively,  with  this option string arguments may be in the
              form $var in which case the value of  the  variable  is  substi-
              tuted.   Note  this form is strict; the string argument does not
              undergo general parameter expansion.

              For example,

                     sep=:
                     val=a:b:c
                     print ${(ps.$sep.)val}

              splits the variable on a :.

       ~      Strings inserted into the expansion by any of  the  flags  below
              are to be treated as patterns.  This applies to the string argu-
              ments of flags that follow ~ within the same set of parentheses.
              Compare with ~ outside parentheses, which forces the entire sub-
              stituted string to be treated as a pattern.  Hence, for example,

                     [[ "?" = ${(~j.|.)array} ]]

              treats `|' as a pattern and succeeds if and only if $array  con-
              tains  the  string  `?' as an element.  The ~ may be repeated to
              toggle the behaviour; its effect only lasts to the  end  of  the
              parenthesised group.

       j:string:
              Join  the  words of arrays together using string as a separator.
              Note that this occurs before field splitting  by  the  s:string:
              flag or the SH_WORD_SPLIT option.

       l:expr::string1::string2:
              Pad  the  resulting  words on the left.  Each word will be trun-
              cated if required and placed in a field expr characters wide.

              The arguments :string1: and :string2: are optional; neither, the
              first, or both may be given.  Note that the same pairs of delim-
              iters must be used for each of the three arguments.   The  space
              to  the  left will be filled with string1 (concatenated as often
              as needed) or spaces if string1 is not given.  If  both  string1
              and  string2 are given, string2 is inserted once directly to the
              left of each word, truncated if  necessary,  before  string1  is
              used to produce any remaining padding.

              If either of string1 or string2 is present but empty, i.e. there
              are two delimiters together at that point, the  first  character
              of $IFS is used instead.

              If  the  MULTIBYTE  option  is in effect, the flag m may also be
              given, in which case widths will be used for the calculation  of
              padding;  otherwise  individual multibyte characters are treated
              as occupying one unit of width.

              If the MULTIBYTE option is not  in  effect,  each  byte  in  the
              string is treated as occupying one unit of width.

              Control  characters are always assumed to be one unit wide; this
              allows the mechanism to be used for  generating  repetitions  of
              control characters.

       m      Only  useful together with one of the flags l or r or with the #
              length operator when the MULTIBYTE option is in effect.  Use the
              character  width  reported by the system in calculating how much
              of the string it occupies or the overall length of  the  string.
              Most printable characters have a width of one unit, however cer-
              tain Asian character sets and certain special effects use  wider
              characters; combining characters have zero width.  Non-printable
              characters are arbitrarily counted as zero width; how they would
              actually be displayed will vary.

              If  the  m  is repeated, the character either counts zero (if it
              has zero width), else one.  For printable character strings this
              has  the  effect of counting the number of glyphs (visibly sepa-
              rate characters), except for the case where combining characters
              themselves have non-zero width (true in certain alphabets).

       r:expr::string1::string2:
              As  l, but pad the words on the right and insert string2 immedi-
              ately to the right of the string to be padded.

              Left and right padding may be used together.  In this  case  the
              strategy  is  to  apply  left padding to the first half width of
              each of the resulting words, and right  padding  to  the  second
              half.   If  the string to be padded has odd width the extra pad-
              ding is applied on the left.

       s:string:
              Force field splitting at the  separator  string.   Note  that  a
              string  of  two  or  more characters means that all of them must
              match in sequence; this differs from the  treatment  of  two  or
              more  characters  in the IFS parameter.  See also the = flag and
              the SH_WORD_SPLIT option.  An empty string may also be given  in
              which case every character will be a separate element.

              For  historical  reasons,  the  usual behaviour that empty array
              elements are retained  inside  double  quotes  is  disabled  for
              arrays generated by splitting; hence the following:

                     line="one::three"
                     print -l "${(s.:.)line}"

              produces  two  lines  of output for one and three and elides the
              empty field.  To override this behaviour, supply the `(@)'  flag
              as well, i.e.  "${(@s.:.)line}".

       Z:opts:
              As z but takes a combination of option letters between a follow-
              ing pair of delimiter characters.  With no options the effect is
              identical to z.  (Z+c+) causes comments to be parsed as a string
              and retained; any field in the resulting array beginning with an
              unquoted comment character is a comment.  (Z+C+) causes comments
              to be parsed and removed.  The rule for  comments  is  standard:
              anything  between  a  word  starting with the third character of
              $HISTCHARS, default #, up to the  next  newline  is  a  comment.
              (Z+n+) causes unquoted newlines to be treated as ordinary white-
              space, else they are treated as if they are  shell  code  delim-
              iters  and converted to semicolons.  Options are combined within
              the same set of delimiters, e.g. (Z+Cn+).

       _:flags:
              The underscore (_) flag is reserved for future use.  As of  this
              revision of zsh, there are no valid flags; anything following an
              underscore, other than an empty pair of delimiters,  is  treated
              as an error, and the flag itself has no effect.

       The  following  flags  are meaningful with the ${...#...} or ${...%...}
       forms.  The S and I flags may also be used with the ${.../...} forms.

       S      Search substrings as well as beginnings or ends;  with  #  start
              from  the beginning and with % start from the end of the string.
              With  substitution  via  ${.../...}  or  ${...//...},  specifies
              non-greedy matching, i.e. that the shortest instead of the long-
              est match should be replaced.

       I:expr:
              Search the exprth match (where  expr  evaluates  to  a  number).
              This only applies when searching for substrings, either with the
              S flag, or with ${.../...} (only the  exprth  match  is  substi-
              tuted)  or  ${...//...} (all matches from the exprth on are sub-
              stituted).  The default is to take the first match.

              The exprth match is counted such that there  is  either  one  or
              zero matches from each starting position in the string, although
              for global substitution matches  overlapping  previous  replace-
              ments  are  ignored.  With the ${...%...} and ${...%%...} forms,
              the starting position for the match moves backwards from the end
              as the index increases, while with the other forms it moves for-
              ward from the start.

              Hence with the string
                     which switch is the right switch for Ipswich?
              substitutions of the form ${(SI:N:)string#w*ch} as  N  increases
              from  1  will  match  and  remove  `which', `witch', `witch' and
              `wich'; the form using `##' will match and remove `which  switch
              is the right switch for Ipswich', `witch is the right switch for
              Ipswich', `witch for Ipswich' and `wich'.  The  form  using  `%'
              will  remove  the same matches as for `#', but in reverse order,
              and the form using `%%' will remove the same matches as for `##'
              in reverse order.

       B      Include the index of the beginning of the match in the result.

       E      Include the index one character past the end of the match in the
              result (note this is inconsistent with other uses  of  parameter
              index).

       M      Include the matched portion in the result.

       N      Include the length of the match in the result.

       R      Include the unmatched portion in the result (the Rest).

   Rules
       Here  is  a  summary  of  the rules for substitution; this assumes that
       braces are present around the substitution, i.e. ${...}.  Some particu-
       lar  examples  are  given  below.   Note that the Zsh Development Group
       accepts no responsibility for any brain damage which may  occur  during
       the reading of the following rules.

       1. Nested substitution
              If  multiple  nested  ${...}  forms are present, substitution is
              performed from the inside outwards.  At each level, the  substi-
              tution takes account of whether the current value is a scalar or
              an array, whether the whole substitution is  in  double  quotes,
              and  what  flags  are supplied to the current level of substitu-
              tion, just as if the nested  substitution  were  the  outermost.
              The  flags are not propagated up to enclosing substitutions; the
              nested substitution will return either a scalar or an  array  as
              determined by the flags, possibly adjusted for quoting.  All the
              following steps take place where applicable  at  all  levels  of
              substitution.

              Note  that,  unless the `(P)' flag is present, the flags and any
              subscripts apply directly to the value of the  nested  substitu-
              tion;  for  example, the expansion ${${foo}} behaves exactly the
              same as ${foo}.  When the `(P)' flag is present in a nested sub-
              stitution, the other substitution rules are applied to the value
              before it is interpreted as a name, so ${${(P)foo}}  may  differ
              from ${(P)foo}.

              At  each  nested  level  of  substitution, the substituted words
              undergo all forms of single-word substitution (i.e. not filename
              generation),  including  command substitution, arithmetic expan-
              sion and filename expansion (i.e. leading ~ and =).   Thus,  for
              example,  ${${:-=cat}:h}  expands to the directory where the cat
              program resides.  (Explanation: the internal substitution has no
              parameter  but  a default value =cat, which is expanded by file-
              name expansion to a  full  path;  the  outer  substitution  then
              applies  the  modifier  :h  and  takes the directory part of the
              path.)

       2. Internal parameter flags
              Any parameter flags set by one of the  typeset  family  of  com-
              mands,  in particular the -L, -R, -Z, -u and -l options for pad-
              ding and capitalization, are applied directly to  the  parameter
              value.  Note these flags are options to the command, e.g. `type-
              set -Z'; they are not the same as the flags used within  parame-
              ter substitutions.

              At the outermost level of substitution, the `(P)' flag (rule 4.)
              ignores these transformations and uses the unmodified  value  of
              the  parameter  as the name to be replaced.  This is usually the
              desired behavior because padding may make  the  value  syntacti-
              cally illegal as a parameter name, but if capitalization changes
              are desired, use the ${${(P)foo}} form (rule 25.).

       3. Parameter subscripting
              If the value is a raw parameter reference with a subscript, such
              as  ${var[3]}, the effect of subscripting is applied directly to
              the parameter.  Subscripts are evaluated left to  right;  subse-
              quent  subscripts  apply to the scalar or array value yielded by
              the previous subscript.  Thus if var is an  array,  ${var[1][2]}
              is the second character of the first word, but ${var[2,4][2]} is
              the entire third word (the second word of the range of words two
              through  four  of the original array).  Any number of subscripts
              may appear.  Flags such as  `(k)'  and  `(v)'  which  alter  the
              result of subscripting are applied.

       4. Parameter name replacement
              At  the  outermost  level  of  nesting  only,  the `(P)' flag is
              applied.  This treats the value  so  far  as  a  parameter  name
              (which  may  include  a  subscript expression) and replaces that
              with the corresponding value.  This replacement occurs later  if
              the `(P)' flag appears in a nested substitution.

              If  the  value  so far names a parameter that has internal flags
              (rule 2.), those internal flags are applied  to  the  new  value
              after replacement.

       5. Double-quoted joining
              If  the  value after this process is an array, and the substitu-
              tion appears in double quotes, and neither an `(@)' flag  nor  a
              `#'  length operator is present at the current level, then words
              of the value are joined with the first character of the  parame-
              ter  $IFS,  by  default  a space, between each word (single word
              arrays are not modified).  If the `(j)' flag is present, that is
              used for joining instead of $IFS.

       6. Nested subscripting
              Any  remaining  subscripts  (i.e.  of a nested substitution) are
              evaluated at this point, based on whether the value is an  array
              or  a scalar.  As with 3., multiple subscripts can appear.  Note
              that ${foo[2,4][2]} is thus equivalent to ${${foo[2,4]}[2]}  and
              also  to "${${(@)foo[2,4]}[2]}" (the nested substitution returns
              an array in both cases), but  not  to  "${${foo[2,4]}[2]}"  (the
              nested substitution returns a scalar because of the quotes).

       7. Modifiers
              Any  modifiers, as specified by a trailing `#', `%', `/' (possi-
              bly doubled) or by a set of modifiers of the  form  `:...'  (see
              the section `Modifiers' in the section `History Expansion'), are
              applied to the words of the value at this level.

       8. Character evaluation
              Any `(#)' flag is applied, evaluating the result so far  numeri-
              cally as a character.

       9. Length
              Any  initial  `#' modifier, i.e. in the form ${#var}, is used to
              evaluate the length of the expression so far.

       10. Forced joining
              If the `(j)' flag is present, or no `(j)' flag  is  present  but
              the  string is to be split as given by rule 11., and joining did
              not take place at rule 5., any words in  the  value  are  joined
              together  using  the given string or the first character of $IFS
              if none.  Note that the `(F)' flag implicitly supplies a  string
              for joining in this manner.

       11. Simple word splitting
              If one of the `(s)' or `(f)' flags are present, or the `=' spec-
              ifier was present (e.g. ${=var}), the word is  split  on  occur-
              rences  of  the  specified string, or (for = with neither of the
              two flags present) any of the characters in $IFS.

              If no `(s)', `(f)' or `=' was given, but the word is not  quoted
              and the option SH_WORD_SPLIT is set, the word is split on occur-
              rences of any of the characters in $IFS.  Note this  step,  too,
              takes place at all levels of a nested substitution.

       12. Case modification
              Any  case  modification  from  one  of the flags `(L)', `(U)' or
              `(C)' is applied.

       13. Escape sequence replacement
              First any replacements from the `(g)' flag are  performed,  then
              any  prompt-style  formatting  from the `(%)' family of flags is
              applied.

       14. Quote application
              Any quoting or unquoting using `(q)' and `(Q)' and related flags
              is applied.

       15. Directory naming
              Any directory name substitution using `(D)' flag is applied.

       16. Visibility enhancement
              Any  modifications  to  make  characters visible using the `(V)'
              flag are applied.

       17. Lexical word splitting
              If the '(z)' flag or one of the  forms  of  the  '(Z)'  flag  is
              present,  the  word is split as if it were a shell command line,
              so that quotation marks and other  metacharacters  are  used  to
              decide  what constitutes a word.  Note this form of splitting is
              entirely distinct from that described by rule 11.: it  does  not
              use $IFS, and does not cause forced joining.

       18. Uniqueness
              If the result is an array and the `(u)' flag was present, dupli-
              cate elements are removed from the array.

       19. Ordering
              If the result is still an array and one of the  `(o)'  or  `(O)'
              flags was present, the array is reordered.

       20. RC_EXPAND_PARAM
              At  this  point the decision is made whether any resulting array
              elements are to be combined element by element with  surrounding
              text,  as  given by either the RC_EXPAND_PARAM option or the `^'
              flag.

       21. Re-evaluation
              Any `(e)' flag is  applied  to  the  value,  forcing  it  to  be
              re-examined  for  new parameter substitutions, but also for com-
              mand and arithmetic substitutions.

       22. Padding
              Any padding of the value by the `(l.fill.)' or `(r.fill.)' flags
              is applied.

       23. Semantic joining
              In  contexts where expansion semantics requires a single word to
              result, all words are rejoined with the first character  of  IFS
              between.   So  in  `${(P)${(f)lines}}'  the value of ${lines} is
              split at newlines, but then must  be  joined  again  before  the
              `(P)' flag can be applied.

              If a single word is not required, this rule is skipped.

       24. Empty argument removal
              If  the  substitution  does  not  appear  in  double quotes, any
              resulting zero-length argument, whether from a scalar or an ele-
              ment  of an array, is elided from the list of arguments inserted
              into the command line.

              Strictly speaking, the removal happens later as the same happens
              with other forms of substitution; the point to note here is sim-
              ply that it occurs after any of the above parameter operations.

       25. Nested parameter name replacement
              If the `(P)' flag is present and rule 4. has  not  applied,  the
              value so far is treated as a parameter name (which may include a
              subscript expression) and replaced with the corresponding value,
              with internal flags (rule 2.) applied to the new value.

   Examples
       The  flag  f  is  useful  to split a double-quoted substitution line by
       line.  For example, ${(f)"$(<file)"} substitutes the contents  of  file
       divided  so  that each line is an element of the resulting array.  Com-
       pare this with the effect of $(<file) alone, which divides the file  up
       by words, or the same inside double quotes, which makes the entire con-
       tent of the file a single string.

       The following illustrates the rules for  nested  parameter  expansions.
       Suppose that $foo contains the array (bar baz):

       "${(@)${foo}[1]}"
              This  produces  the  result  b.   First,  the inner substitution
              "${foo}", which has no array (@) flag, produces  a  single  word
              result "bar baz".  The outer substitution "${(@)...[1]}" detects
              that this is a scalar, so that (despite the `(@)' flag) the sub-
              script picks the first character.

       "${${(@)foo}[1]}"
              This produces the result `bar'.  In this case, the inner substi-
              tution "${(@)foo}" produces the array `(bar  baz)'.   The  outer
              substitution "${...[1]}" detects that this is an array and picks
              the first word.  This is similar to the simple case "${foo[1]}".

       As an example of the rules for word splitting and joining, suppose $foo
       contains the array `(ax1 bx1)'.  Then

       ${(s/x/)foo}
              produces the words `a', `1 b' and `1'.

       ${(j/x/s/x/)foo}
              produces `a', `1', `b' and `1'.

       ${(s/x/)foo%%1*}
              produces  `a'  and ` b' (note the extra space).  As substitution
              occurs before either joining or splitting, the operation   first
              generates  the  modified  array (ax bx), which is joined to give
              "ax bx", and then split to give `a', ` b'  and  `'.   The  final
              empty string will then be elided, as it is not in double quotes.

COMMAND SUBSTITUTION
       A  command  enclosed  in  parentheses  preceded  by a dollar sign, like
       `$(...)', or quoted with grave accents, like ``...`', is replaced  with
       its  standard  output, with any trailing newlines deleted.  If the sub-
       stitution is not enclosed in double quotes, the output is  broken  into
       words  using  the  IFS parameter.  The substitution `$(cat foo)' may be
       replaced by the equivalent but faster `$(<foo)'.  In  either  case,  if
       the  option GLOB_SUBST is set, the output is eligible for filename gen-
       eration.

ARITHMETIC EXPANSION
       A string of the form `$[exp]' or `$((exp))'  is  substituted  with  the
       value  of the arithmetic expression exp.  exp is subjected to parameter
       expansion, command substitution and arithmetic expansion before  it  is
       evaluated.  See the section `Arithmetic Evaluation'.

BRACE EXPANSION
       A  string  of the form `foo{xx,yy,zz}bar' is expanded to the individual
       words `fooxxbar', `fooyybar' and `foozzbar'.   Left-to-right  order  is
       preserved.   This  construct  may  be  nested.  Commas may be quoted in
       order to include them literally in a word.

       An expression of the form `{n1..n2}', where n1 and n2 are integers,  is
       expanded to every number between n1 and n2 inclusive.  If either number
       begins with a zero, all the resulting numbers will be padded with lead-
       ing  zeroes to that minimum width, but for negative numbers the - char-
       acter is also included in the width.  If the numbers are in  decreasing
       order the resulting sequence will also be in decreasing order.

       An  expression  of  the  form  `{n1..n2..n3}', where n1, n2, and n3 are
       integers, is expanded as above, but only  every  n3th  number  starting
       from n1 is output.  If n3 is negative the numbers are output in reverse
       order, this is slightly different from simply swapping n1 and n2 in the
       case  that  the  step n3 doesn't evenly divide the range.  Zero padding
       can be specified in any of the three  numbers,  specifying  it  in  the
       third  can  be  useful to pad for example `{-99..100..01}' which is not
       possible to specify by putting a 0 on either of the first  two  numbers
       (i.e. pad to two characters).

       An  expression of the form `{c1..c2}', where c1 and c2 are single char-
       acters (which may be multibyte characters), is expanded to every  char-
       acter in the range from c1 to c2 in whatever character sequence is used
       internally.  For characters with code points below 128 this is US ASCII
       (this is the only case most users will need).  If any intervening char-
       acter is not printable, appropriate quotation  is  used  to  render  it
       printable.   If  the  character  sequence is reversed, the output is in
       reverse order, e.g. `{d..a}' is substituted as `d c b a'.

       If a brace expression matches none of  the  above  forms,  it  is  left
       unchanged,  unless  the  option  BRACE_CCL  (an abbreviation for `brace
       character class') is set.  In that case, it is expanded to  a  list  of
       the  individual  characters between the braces sorted into the order of
       the characters in the ASCII character set (multibyte characters are not
       currently  handled).   The  syntax  is similar to a [...] expression in
       filename generation: `-' is treated specially  to  denote  a  range  of
       characters,  but `^' or `!' as the first character is treated normally.
       For example, `{abcdef0-9}' expands to 16 words 0 1 2 3 4 5 6 7 8 9 a  b
       c d e f.

       Note  that  brace  expansion  is not part of filename generation (glob-
       bing); an expression such as */{foo,bar} is  split  into  two  separate
       words  */foo and */bar before filename generation takes place.  In par-
       ticular, note that this is liable to produce  a  `no  match'  error  if
       either  of the two expressions does not match; this is to be contrasted
       with */(foo|bar), which is treated as a single  pattern  but  otherwise
       has similar effects.

       To  combine brace expansion with array expansion, see the ${^spec} form
       described in the section Parameter Expansion above.

FILENAME EXPANSION
       Each word is checked to see if it begins with an unquoted `~'.   If  it
       does,  then the word up to a `/', or the end of the word if there is no
       `/', is checked to see if it can be substituted  in  one  of  the  ways
       described  here.   If  so,  then  the  `~'  and the checked portion are
       replaced with the appropriate substitute value.

       A `~' by itself is replaced by the value of $HOME.  A `~' followed by a
       `+'  or  a  `-'  is  replaced by current or previous working directory,
       respectively.

       A `~' followed by a number is replaced by the directory at  that  posi-
       tion  in  the directory stack.  `~0' is equivalent to `~+', and `~1' is
       the top of the stack.  `~+' followed by a number  is  replaced  by  the
       directory at that position in the directory stack.  `~+0' is equivalent
       to `~+', and `~+1' is the top of the stack.  `~-' followed by a  number
       is replaced by the directory that many positions from the bottom of the
       stack.  `~-0' is the bottom  of  the  stack.   The  PUSHD_MINUS  option
       exchanges  the  effects  of  `~+' and `~-' where they are followed by a
       number.

   Dynamic named directories
       If the  function  zsh_directory_name  exists,  or  the  shell  variable
       zsh_directory_name_functions  exists  and contains an array of function
       names, then the functions are used to implement dynamic directory  nam-
       ing.   The  functions are tried in order until one returns status zero,
       so it is important that functions test whether they can handle the case
       in question and return an appropriate status.

       A  `~'  followed  by  a  string  namstr  in unquoted square brackets is
       treated specially as a dynamic directory name.   Note  that  the  first
       unquoted  closing  square  bracket always terminates namstr.  The shell
       function is passed two arguments: the string n (for name)  and  namstr.
       It  should  either set the array reply to a single element which is the
       directory corresponding to the name and return status  zero  (executing
       an  assignment  as  the  last  statement  is usually sufficient), or it
       should return status non-zero.  In the former case the element of reply
       is used as the directory; in the latter case the substitution is deemed
       to have failed.  If all functions fail and the option NOMATCH  is  set,
       an error results.

       The  functions defined as above are also used to see if a directory can
       be turned into a name, for example when printing the directory stack or
       when expanding %~ in prompts.  In this case each function is passed two
       arguments: the string d (for directory) and the candidate  for  dynamic
       naming.   The  function  should  either  return non-zero status, if the
       directory cannot be named by the function, or it should set  the  array
       reply to consist of two elements: the first is the dynamic name for the
       directory (as would appear within `~[...]'), and the second is the pre-
       fix  length of the directory to be replaced.  For example, if the trial
       directory  is   /home/myname/src/zsh   and   the   dynamic   name   for
       /home/myname/src (which has 16 characters) is s, then the function sets

              reply=(s 16)

       The  directory  name so returned is compared with possible static names
       for parts of the directory path, as described below; it is used if  the
       prefix  length  matched (16 in the example) is longer than that matched
       by any static name.

       It is not a requirement that a function implements both n and d  calls;
       for  example,  it  might  be  appropriate  for certain dynamic forms of
       expansion not to be contracted to names.  In that case  any  call  with
       the first argument d should cause a non-zero status to be returned.

       The  completion system calls `zsh_directory_name c' followed by equiva-
       lent calls to elements of the array zsh_directory_name_functions, if it
       exists,  in  order to complete dynamic names for directories.  The code
       for this should be as for any other completion function as described in
       zshcompsys(1).

       As a working example, here is a function that expands any dynamic names
       beginning with the string p: to directories  below  /home/pws/perforce.
       In  this  simple  case a static name for the directory would be just as
       effective.

              zsh_directory_name() {
                emulate -L zsh
                setopt extendedglob
                local -a match mbegin mend
                if [[ $1 = d ]]; then
                  # turn the directory into a name
                  if [[ $2 = (#b)(/home/pws/perforce/)([^/]##)* ]]; then
                    typeset -ga reply
                    reply=(p:$match[2] $(( ${#match[1]} + ${#match[2]} )) )
                  else
                    return 1
                  fi
                elif [[ $1 = n ]]; then
                  # turn the name into a directory
                  [[ $2 != (#b)p:(?*) ]] && return 1
                  typeset -ga reply
                  reply=(/home/pws/perforce/$match[1])
                elif [[ $1 = c ]]; then
                  # complete names
                  local expl
                  local -a dirs
                  dirs=(/home/pws/perforce/*(/:t))
                  dirs=(p:${^dirs})
                  _wanted dynamic-dirs expl 'dynamic directory' compadd -S\] -a dirs
                  return
                else
                  return 1
                fi
                return 0
              }

   Static named directories
       A `~' followed by anything not already covered consisting of any number
       of  alphanumeric  characters  or underscore (`_'), hyphen (`-'), or dot
       (`.') is looked up as a named directory, and replaced by the  value  of
       that  named  directory  if found.  Named directories are typically home
       directories for users on the system.  They may also be defined  if  the
       text  after the `~' is the name of a string shell parameter whose value
       begins with a `/'.  Note that trailing slashes will be removed from the
       path to the directory (though the original parameter is not modified).

       It  is  also  possible to define directory names using the -d option to
       the hash builtin.

       When the shell prints a path (e.g. when expanding %~ in prompts or when
       printing  the  directory stack), the path is checked to see if it has a
       named directory as its prefix.  If  so,  then  the  prefix  portion  is
       replaced with a `~' followed by the name of the directory.  The shorter
       of the two ways of referring to the directory is used, i.e. either  the
       directory  name or the full path; the name is used if they are the same
       length.  The parameters $PWD and $OLDPWD are never abbreviated in  this
       fashion.

   `=' expansion
       If a word begins with an unquoted `=' and the EQUALS option is set, the
       remainder of the word is taken as the name of a command.  If a  command
       exists  by  that name, the word is replaced by the full pathname of the
       command.

   Notes
       Filename expansion is performed on the right hand side of  a  parameter
       assignment,  including  those  appearing  after commands of the typeset
       family.  In this case, the  right  hand  side  will  be  treated  as  a
       colon-separated list in the manner of the PATH parameter, so that a `~'
       or an `=' following a `:' is eligible for expansion.  All  such  behav-
       iour  can be disabled by quoting the `~', the `=', or the whole expres-
       sion (but not simply the colon); the EQUALS option is also respected.

       If the option MAGIC_EQUAL_SUBST is set, any unquoted shell argument  in
       the form `identifier=expression' becomes eligible for file expansion as
       described in the  previous  paragraph.   Quoting  the  first  `='  also
       inhibits this.

FILENAME GENERATION
       If  a  word contains an unquoted instance of one of the characters `*',
       `(', `|', `<', `[', or `?', it is regarded as a  pattern  for  filename
       generation,  unless  the  GLOB  option  is unset.  If the EXTENDED_GLOB
       option is set, the `^' and `#' characters also denote a pattern; other-
       wise they are not treated specially by the shell.

       The  word  is  replaced  with a list of sorted filenames that match the
       pattern.  If no matching pattern is found, the  shell  gives  an  error
       message,  unless the NULL_GLOB option is set, in which case the word is
       deleted; or unless the NOMATCH option is unset, in which case the  word
       is left unchanged.

       In  filename  generation, the character `/' must be matched explicitly;
       also, a `.' must be matched explicitly at the beginning of a pattern or
       after  a  `/', unless the GLOB_DOTS option is set.  No filename genera-
       tion pattern matches the files `.' or `..'.  In other instances of pat-
       tern matching, the `/' and `.' are not treated specially.

   Glob Operators
       *      Matches any string, including the null string.

       ?      Matches any character.

       [...]  Matches  any  of  the enclosed characters.  Ranges of characters
              can be specified by separating two characters by a `-'.   A  `-'
              or  `]' may be matched by including it as the first character in
              the list.  There are also several named classes  of  characters,
              in  the  form `[:name:]' with the following meanings.  The first
              set use the macros provided by the operating system to test  for
              the  given  character  combinations, including any modifications
              due to local language settings, see ctype(3):

              [:alnum:]
                     The character is alphanumeric

              [:alpha:]
                     The character is alphabetic

              [:ascii:]
                     The character is 7-bit, i.e. is a  single-byte  character
                     without the top bit set.

              [:blank:]
                     The character is a blank character

              [:cntrl:]
                     The character is a control character

              [:digit:]
                     The character is a decimal digit

              [:graph:]
                     The  character is a printable character other than white-
                     space

              [:lower:]
                     The character is a lowercase letter

              [:print:]
                     The character is printable

              [:punct:]
                     The character is printable but neither  alphanumeric  nor
                     whitespace

              [:space:]
                     The character is whitespace

              [:upper:]
                     The character is an uppercase letter

              [:xdigit:]
                     The character is a hexadecimal digit

              Another  set of named classes is handled internally by the shell
              and is not sensitive to the locale:

              [:IDENT:]
                     The character is allowed to form part of a shell  identi-
                     fier, such as a parameter name

              [:IFS:]
                     The  character  is used as an input field separator, i.e.
                     is contained in the IFS parameter

              [:IFSSPACE:]
                     The character is an IFS white space  character;  see  the
                     documentation for IFS in the zshparam(1) manual page.

              [:INCOMPLETE:]
                     Matches  a byte that starts an incomplete multibyte char-
                     acter.  Note that there may be a sequence  of  more  than
                     one bytes that taken together form the prefix of a multi-
                     byte character.  To test  for  a  potentially  incomplete
                     byte sequence, use the pattern `[[:INCOMPLETE:]]*'.  This
                     will never match a sequence starting with a valid  multi-
                     byte character.

              [:INVALID:]
                     Matches  a  byte  that  does  not start a valid multibyte
                     character.  Note this may be a continuation  byte  of  an
                     incomplete multibyte character as any part of a multibyte
                     string consisting of  invalid  and  incomplete  multibyte
                     characters is treated as single bytes.

              [:WORD:]
                     The  character is treated as part of a word; this test is
                     sensitive to the value of the WORDCHARS parameter

              Note that the square brackets are additional to those  enclosing
              the  whole  set  of characters, so to test for a single alphanu-
              meric character you need `[[:alnum:]]'.   Named  character  sets
              can be used alongside other types, e.g. `[[:alpha:]0-9]'.

       [^...]
       [!...] Like [...], except that it matches any character which is not in
              the given set.

       <[x]-[y]>
              Matches any number in the range x to y,  inclusive.   Either  of
              the  numbers  may be omitted to make the range open-ended; hence
              `<->' matches any number.  To match individual digits, the [...]
              form is more efficient.

              Be  careful  when  using other wildcards adjacent to patterns of
              this form; for example, <0-9>* will actually  match  any  number
              whatsoever  at  the  start of the string, since the `<0-9>' will
              match the first digit, and the `*' will match any others.   This
              is  a  trap  for the unwary, but is in fact an inevitable conse-
              quence of the rule that the longest possible match  always  suc-
              ceeds.   Expressions  such  as  `<0-9>[^[:digit:]]*' can be used
              instead.

       (...)  Matches the enclosed pattern.  This is used  for  grouping.   If
              the  KSH_GLOB  option  is  set, then a `@', `*', `+', `?' or `!'
              immediately preceding the `(' is treated specially, as  detailed
              below.  The  option SH_GLOB prevents bare parentheses from being
              used in this way, though the KSH_GLOB option is still available.

              Note that grouping cannot extend over multiple  directories:  it
              is  an error to have a `/' within a group (this only applies for
              patterns used in filename generation).  There is one  exception:
              a group of the form (pat/)# appearing as a complete path segment
              can match a sequence of directories.  For example, foo/(a*/)#bar
              matches foo/bar, foo/any/bar, foo/any/anyother/bar, and so on.

       x|y    Matches  either x or y.  This operator has lower precedence than
              any other.  The `|' character must  be  within  parentheses,  to
              avoid  interpretation as a pipeline.  The alternatives are tried
              in order from left to right.

       ^x     (Requires EXTENDED_GLOB to be set.)  Matches anything except the
              pattern x.  This has a higher precedence than `/', so `^foo/bar'
              will search directories in `.' except `./foo' for a  file  named
              `bar'.

       x~y    (Requires EXTENDED_GLOB to be set.)  Match anything that matches
              the pattern x but does not match y.  This has  lower  precedence
              than  any  operator except `|', so `*/*~foo/bar' will search for
              all files in all directories in `.'  and then exclude  `foo/bar'
              if there was such a match.  Multiple patterns can be excluded by
              `foo~bar~baz'.  In the exclusion pattern (y), `/'  and  `.'  are
              not treated specially the way they usually are in globbing.

       x#     (Requires EXTENDED_GLOB to be set.)  Matches zero or more occur-
              rences of the pattern x.  This  operator  has  high  precedence;
              `12#'  is  equivalent to `1(2#)', rather than `(12)#'.  It is an
              error for an unquoted `#' to follow something  which  cannot  be
              repeated;  this includes an empty string, a pattern already fol-
              lowed by `##', or parentheses when part of  a  KSH_GLOB  pattern
              (for  example,  `!(foo)#'  is  invalid  and  must be replaced by
              `*(!(foo))').

       x##    (Requires EXTENDED_GLOB to be set.)  Matches one or more  occur-
              rences  of  the  pattern  x.  This operator has high precedence;
              `12##' is equivalent to `1(2##)', rather than `(12)##'.  No more
              than  two  active `#' characters may appear together.  (Note the
              potential clash with glob qualifiers in the form `1(2##)'  which
              should therefore be avoided.)

   ksh-like Glob Operators
       If  the KSH_GLOB option is set, the effects of parentheses can be modi-
       fied by a preceding `@', `*', `+', `?' or `!'.  This character need not
       be unquoted to have special effects, but the `(' must be.

       @(...) Match the pattern in the parentheses.  (Like `(...)'.)

       *(...) Match  any  number  of occurrences.  (Like `(...)#', except that
              recursive directory searching is not supported.)

       +(...) Match at least one occurrence.   (Like  `(...)##',  except  that
              recursive directory searching is not supported.)

       ?(...) Match zero or one occurrence.  (Like `(|...)'.)

       !(...) Match   anything  but  the  expression  in  parentheses.   (Like
              `(^(...))'.)

   Precedence
       The precedence of the operators given above is (highest) `^', `/', `~',
       `|'  (lowest);  the remaining operators are simply treated from left to
       right as part of a string, with `#' and `##' applying to  the  shortest
       possible  preceding unit (i.e. a character, `?', `[...]', `<...>', or a
       parenthesised expression).  As mentioned above, a `/' used as a  direc-
       tory  separator  may not appear inside parentheses, while a `|' must do
       so; in patterns used in other contexts than  filename  generation  (for
       example,  in  case statements and tests within `[[...]]'), a `/' is not
       special; and `/' is also not special  after  a  `~'  appearing  outside
       parentheses in a filename pattern.

   Globbing Flags
       There  are various flags which affect any text to their right up to the
       end of the enclosing group or to the end of the pattern;  they  require
       the  EXTENDED_GLOB  option. All take the form (#X) where X may have one
       of the following forms:

       i      Case insensitive:  upper or lower case characters in the pattern
              match upper or lower case characters.

       l      Lower  case  characters in the pattern match upper or lower case
              characters; upper case characters  in  the  pattern  still  only
              match upper case characters.

       I      Case  sensitive:  locally negates the effect of i or l from that
              point on.

       b      Activate backreferences for parenthesised groups in the pattern;
              this  does not work in filename generation.  When a pattern with
              a set of active parentheses is matched, the strings  matched  by
              the  groups  are  stored in the array $match, the indices of the
              beginning of the matched parentheses in the array  $mbegin,  and
              the  indices  of the end in the array $mend, with the first ele-
              ment of each array  corresponding  to  the  first  parenthesised
              group, and so on.  These arrays are not otherwise special to the
              shell.  The indices use the same convention  as  does  parameter
              substitution,  so that elements of $mend and $mbegin may be used
              in subscripts; the KSH_ARRAYS  option  is  respected.   Sets  of
              globbing flags are not considered parenthesised groups; only the
              first nine active parentheses can be referenced.

              For example,

                     foo="a string with a message"
                     if [[ $foo = (a|an)' '(#b)(*)' '* ]]; then
                       print ${foo[$mbegin[1],$mend[1]]}
                     fi

              prints `string with a'.  Note  that  the  first  parenthesis  is
              before the (#b) and does not create a backreference.

              Backreferences  work  with  all  forms of pattern matching other
              than filename generation, but note that when performing  matches
              on  an  entire array, such as ${array#pattern}, or a global sub-
              stitution, such as ${param//pat/repl}, only  the  data  for  the
              last  match  remains  available.  In the case of global replace-
              ments this may still be useful.  See the example for the m  flag
              below.

              The  numbering  of  backreferences strictly follows the order of
              the opening parentheses  from  left  to  right  in  the  pattern
              string,  although  sets of parentheses may be nested.  There are
              special rules for parentheses followed by `#' or `##'.  Only the
              last match of the parenthesis is remembered: for example, in `[[
              abab =  (#b)([ab])#  ]]',  only  the  final  `b'  is  stored  in
              match[1].   Thus extra parentheses may be necessary to match the
              complete segment: for example, use  `X((ab|cd)#)Y'  to  match  a
              whole  string  of either `ab' or `cd' between `X' and `Y', using
              the value of $match[1] rather than $match[2].

              If the match fails none of the parameters is altered, so in some
              cases  it  may  be  necessary to initialise them beforehand.  If
              some of the backreferences fail to match  --  which  happens  if
              they are in an alternate branch which fails to match, or if they
              are followed by # and matched zero times  --  then  the  matched
              string is set to the empty string, and the start and end indices
              are set to -1.

              Pattern matching with backreferences  is  slightly  slower  than
              without.

       B      Deactivate  backreferences,  negating  the  effect of the b flag
              from that point on.

       cN,M   The flag (#cN,M) can be used anywhere that the # or ## operators
              can  be  used  except in the expressions `(*/)#' and `(*/)##' in
              filename generation, where `/' has special meaning; it cannot be
              combined  with  other  globbing  flags  and  a bad pattern error
              occurs if it is misplaced.  It is equivalent to the  form  {N,M}
              in  regular  expressions.   The  previous  character or group is
              required to match between N and M times,  inclusive.   The  form
              (#cN) requires exactly N matches; (#c,M) is equivalent to speci-
              fying N as 0; (#cN,) specifies that there is no maximum limit on
              the number of matches.

       m      Set  references to the match data for the entire string matched;
              this is similar to backreferencing and does not work in filename
              generation.   The  flag must be in effect at the end of the pat-
              tern, i.e. not local to a group. The parameters $MATCH,  $MBEGIN
              and  $MEND  will be set to the string matched and to the indices
              of the beginning and end of the string, respectively.   This  is
              most  useful in parameter substitutions, as otherwise the string
              matched is obvious.

              For example,

                     arr=(veldt jynx grimps waqf zho buck)
                     print ${arr//(#m)[aeiou]/${(U)MATCH}}

              forces all the matches (i.e. all vowels) into uppercase,  print-
              ing `vEldt jynx grImps wAqf zhO bUck'.

              Unlike backreferences, there is no speed penalty for using match
              references, other than the extra substitutions required for  the
              replacement strings in cases such as the example shown.

       M      Deactivate the m flag, hence no references to match data will be
              created.

       anum   Approximate matching: num  errors  are  allowed  in  the  string
              matched by the pattern.  The rules for this are described in the
              next subsection.

       s, e   Unlike the other flags, these have only a local effect, and each
              must  appear  on  its own:  `(#s)' and `(#e)' are the only valid
              forms.  The `(#s)' flag succeeds only at the start of  the  test
              string, and the `(#e)' flag succeeds only at the end of the test
              string; they correspond to  `^'  and  `$'  in  standard  regular
              expressions.  They are useful for matching path segments in pat-
              terns other than those in filename generation (where  path  seg-
              ments  are  in  any  case  treated  separately).   For  example,
              `*((#s)|/)test((#e)|/)*' matches a path segment `test' in any of
              the   following   strings:   test,  test/at/start,  at/end/test,
              in/test/middle.

              Another  use  is  in   parameter   substitution;   for   example
              `${array/(#s)A*Z(#e)}'  will  remove  only  elements of an array
              which match the complete pattern `A*Z'.  There are other ways of
              performing many operations of this type, however the combination
              of the substitution operations `/' and `//' with the `(#s)'  and
              `(#e)' flags provides a single simple and memorable method.

              Note that assertions of the form `(^(#s))' also work, i.e. match
              anywhere except at the start of the string, although this  actu-
              ally  means  `anything except a zero-length portion at the start
              of  the  string';  you  need  to  use  `(""~(#s))'  to  match  a
              zero-length portion of the string not at the start.

       q      A  `q' and everything up to the closing parenthesis of the glob-
              bing flags are ignored by the pattern matching  code.   This  is
              intended  to support the use of glob qualifiers, see below.  The
              result is that the pattern `(#b)(*).c(#q.)' can be used both for
              globbing and for matching against a string.  In the former case,
              the `(#q.)' will be treated as a glob qualifier and  the  `(#b)'
              will  not be useful, while in the latter case the `(#b)' is use-
              ful for backreferences and the `(#q.)' will  be  ignored.   Note
              that colon modifiers in the glob qualifiers are also not applied
              in ordinary pattern matching.

       u      Respect the current locale in determining the presence of multi-
              byte  characters  in  a pattern, provided the shell was compiled
              with MULTIBYTE_SUPPORT.  This overrides  the  MULTIBYTE  option;
              the  default  behaviour  is  taken  from the option.  Compare U.
              (Mnemonic: typically multibyte characters are  from  Unicode  in
              the UTF-8 encoding, although any extension of ASCII supported by
              the system library may be used.)

       U      All characters are considered to be a  single  byte  long.   The
              opposite of u.  This overrides the MULTIBYTE option.

       For  example,  the  test  string  fooxx  can  be matched by the pattern
       (#i)FOOXX, but not by (#l)FOOXX,  (#i)FOO(#I)XX  or  ((#i)FOOX)X.   The
       string  (#ia2)readme specifies case-insensitive matching of readme with
       up to two errors.

       When using the ksh syntax for grouping both KSH_GLOB and  EXTENDED_GLOB
       must  be  set  and  the left parenthesis should be preceded by @.  Note
       also that the flags do not affect letters inside [...] groups, in other
       words  (#i)[a-z]  still  matches only lowercase letters.  Finally, note
       that when examining whole paths case-insensitively every directory must
       be  searched  for  all files which match, so that a pattern of the form
       (#i)/foo/bar/... is potentially slow.

   Approximate Matching
       When matching approximately, the shell keeps  a  count  of  the  errors
       found,  which  cannot exceed the number specified in the (#anum) flags.
       Four types of error are recognised:

       1.     Different characters, as in fooxbar and fooybar.

       2.     Transposition of characters, as in banana and abnana.

       3.     A character missing in the target string, as  with  the  pattern
              road and target string rod.

       4.     An extra character appearing in the target string, as with stove
              and strove.

       Thus, the pattern (#a3)abcd matches dcba, with the errors occurring  by
       using  the first rule twice and the second once, grouping the string as
       [d][cb][a] and [a][bc][d].

       Non-literal parts of the pattern must match exactly, including  charac-
       ters  in  character  ranges:  hence (#a1)???  matches strings of length
       four, by applying rule 4 to an empty  part  of  the  pattern,  but  not
       strings  of  length  two, since all the ? must match.  Other characters
       which must match exactly are initial  dots  in  filenames  (unless  the
       GLOB_DOTS option is set), and all slashes in filenames, so that a/bc is
       two errors from ab/c (the slash cannot be transposed with another char-
       acter).   Similarly,  errors  are counted separately for non-contiguous
       strings in the pattern, so that (ab|cd)ef is two errors from aebf.

       When using exclusion  via  the  ~  operator,  approximate  matching  is
       treated entirely separately for the excluded part and must be activated
       separately.  Thus, (#a1)README~READ_ME matches READ.ME but not READ_ME,
       as  the  trailing  READ_ME  is matched without approximation.  However,
       (#a1)README~(#a1)READ_ME does not match any pattern of the form READ?ME
       as all such forms are now excluded.

       Apart  from exclusions, there is only one overall error count; however,
       the maximum errors allowed may be altered  locally,  and  this  can  be
       delimited  by  grouping.  For example, (#a1)cat((#a0)dog)fox allows one
       error in total, which may not occur in the dog section, and the pattern
       (#a1)cat(#a0)dog(#a1)fox  is  equivalent.  Note that the point at which
       an error is first found is the crucial one for establishing whether  to
       use   approximation;  for  example,  (#a1)abc(#a0)xyz  will  not  match
       abcdxyz, because the error occurs at the `x',  where  approximation  is
       turned off.

       Entire   path   segments   may   be   matched  approximately,  so  that
       `(#a1)/foo/d/is/available/at/the/bar' allows one error in any path seg-
       ment.   This  is  much  less efficient than without the (#a1), however,
       since every directory in the  path  must  be  scanned  for  a  possible
       approximate  match.   It is best to place the (#a1) after any path seg-
       ments which are known to be correct.

   Recursive Globbing
       A pathname component of the form `(foo/)#' matches a path consisting of
       zero or more directories matching the pattern foo.

       As  a  shorthand, `**/' is equivalent to `(*/)#'; note that this there-
       fore matches files in the current directory as well as  subdirectories.
       Thus:

              ls (*/)#bar

       or

              ls **/bar

       does  a  recursive  directory search for files named `bar' (potentially
       including the file `bar' in the current directory).  This form does not
       follow  symbolic links; the alternative form `***/' does, but is other-
       wise identical.  Neither of these can be combined with other  forms  of
       globbing  within the same path segment; in that case, the `*' operators
       revert to their usual effect.

       Even shorter forms are available when  the  option  GLOB_STAR_SHORT  is
       set.   In  that  case  if no / immediately follows a ** or *** they are
       treated as if both a / plus a further * are present.  Hence:

              setopt GLOBSTARSHORT
              ls **.c

       is equivalent to

              ls **/*.c

   Glob Qualifiers
       Patterns used for filename generation may end in a list  of  qualifiers
       enclosed  in  parentheses.  The qualifiers specify which filenames that
       otherwise match the given pattern will  be  inserted  in  the  argument
       list.

       If the option BARE_GLOB_QUAL is set, then a trailing set of parentheses
       containing no `|' or `(' characters (or `~' if it is special) is  taken
       as  a set of glob qualifiers.  A glob subexpression that would normally
       be taken as glob qualifiers, for example `(^x)', can be  forced  to  be
       treated  as  part  of  the glob pattern by doubling the parentheses, in
       this case producing `((^x))'.

       If the option EXTENDED_GLOB is set, a different syntax for glob  quali-
       fiers  is  available,  namely  `(#qx)'  where x is any of the same glob
       qualifiers used in the other format.  The qualifiers must still  appear
       at  the  end  of  the pattern.  However, with this syntax multiple glob
       qualifiers may be chained together.  They are treated as a logical  AND
       of  the  individual sets of flags.  Also, as the syntax is unambiguous,
       the expression will be treated as glob  qualifiers  just  as  long  any
       parentheses contained within it are balanced; appearance of `|', `(' or
       `~' does not negate the effect.  Note that qualifiers  will  be  recog-
       nised  in  this form even if a bare glob qualifier exists at the end of
       the pattern, for example `*(#q*)(.)' will recognise executable  regular
       files if both options are set; however, mixed syntax should probably be
       avoided for the sake of clarity.  Note that within conditions using the
       `[[' form the presence of a parenthesised expression (#q...) at the end
       of a string indicates that globbing should be performed; the expression
       may include glob qualifiers, but it is also valid if it is simply (#q).
       This does not apply to the right hand side of pattern  match  operators
       as the syntax already has special significance.

       A qualifier may be any one of the following:

       /      directories

       F      `full'  (i.e.  non-empty)  directories.   Note that the opposite
              sense (^F) expands to empty directories and all non-directories.
              Use (/^F) for empty directories.

       .      plain files

       @      symbolic links

       =      sockets

       p      named pipes (FIFOs)

       *      executable plain files (0100 or 0010 or 0001)

       %      device files (character or block special)

       %b     block special files

       %c     character special files

       r      owner-readable files (0400)

       w      owner-writable files (0200)

       x      owner-executable files (0100)

       A      group-readable files (0040)

       I      group-writable files (0020)

       E      group-executable files (0010)

       R      world-readable files (0004)

       W      world-writable files (0002)

       X      world-executable files (0001)

       s      setuid files (04000)

       S      setgid files (02000)

       t      files with the sticky bit (01000)

       fspec  files with access rights matching spec. This spec may be a octal
              number optionally preceded by a `=', a `+', or a `-'. If none of
              these  characters is given, the behavior is the same as for `='.
              The octal number describes the mode bits to be expected, if com-
              bined  with  a  `=',  the  value given must match the file-modes
              exactly, with a `+', at least the bits in the given number  must
              be set in the file-modes, and with a `-', the bits in the number
              must not be set. Giving a `?' instead of a octal digit  anywhere
              in  the  number  ensures  that  the  corresponding  bits  in the
              file-modes are not checked, this is only useful  in  combination
              with `='.

              If the qualifier `f' is followed by any other character anything
              up to the next matching character (`[', `{', and `<' match  `]',
              `}',  and  `>' respectively, any other character matches itself)
              is taken as a list of comma-separated sub-specs.  Each  sub-spec
              may  be  either  an octal number as described above or a list of
              any of the characters `u', `g', `o', and `a', followed by a `=',
              a  `+',  or  a  `-', followed by a list of any of the characters
              `r', `w', `x', `s', and `t', or an octal digit. The  first  list
              of  characters specify which access rights are to be checked. If
              a `u' is given, those for the owner of the file are used,  if  a
              `g'  is  given,  those  of the group are checked, a `o' means to
              test those of other users, and the `a' says to  test  all  three
              groups. The `=', `+', and `-' again says how the modes are to be
              checked and have the same meaning as  described  for  the  first
              form  above.  The  second  list of characters finally says which
              access rights are to be expected: `r' for read access,  `w'  for
              write  access,  `x'  for  the  right  to execute the file (or to
              search a directory), `s' for the setuid and setgid bits, and `t'
              for the sticky bit.

              Thus,  `*(f70?)'  gives  the files for which the owner has read,
              write, and execute permission, and for which other group members
              have  no rights, independent of the permissions for other users.
              The pattern `*(f-100)' gives all files for which the owner  does
              not  have  execute  permission,  and `*(f:gu+w,o-rx:)' gives the
              files for which the owner and the other  members  of  the  group
              have  at least write permission, and for which other users don't
              have read or execute permission.

       estring
       +cmd   The string will be executed as shell code.  The filename will be
              included in the list if and only if the code returns a zero sta-
              tus (usually the status of the last command).

              In the first form, the first character after  the  `e'  will  be
              used as a separator and anything up to the next matching separa-
              tor will be taken  as the string; `[', `{', and `<'  match  `]',
              `}',  and  `>',  respectively, while any other character matches
              itself. Note that expansions must be quoted  in  the  string  to
              prevent  them  from  being  expanded  before  globbing  is done.
              string is then executed as shell code.  The string  globqual  is
              appended  to  the  array zsh_eval_context the duration of execu-
              tion.

              During the execution of  string  the  filename  currently  being
              tested is available in the parameter REPLY; the parameter may be
              altered to a string to be inserted into the list instead of  the
              original  filename.  In addition, the parameter reply may be set
              to an array or a string, which overrides the value of REPLY.  If
              set  to  an  array, the latter is inserted into the command line
              word by word.

              For  example,  suppose  a  directory  contains  a  single   file
              `lonely'.   Then  the expression `*(e:'reply=(${REPLY}{1,2})':)'
              will cause the words `lonely1' and `lonely2' to be inserted into
              the command line.  Note the quoting of string.

              The  form  +cmd  has  the  same effect, but no delimiters appear
              around cmd.  Instead, cmd is taken as the  longest  sequence  of
              characters  following the + that are alphanumeric or underscore.
              Typically cmd will be the name of a shell function that contains
              the appropriate test.  For example,

                     nt() { [[ $REPLY -nt $NTREF ]] }
                     NTREF=reffile
                     ls -l *(+nt)

              lists  all  files  in the directory that have been modified more
              recently than reffile.

       ddev   files on the device dev

       l[-|+]ct
              files having a link count less than ct (-), greater than ct (+),
              or equal to ct

       U      files owned by the effective user ID

       G      files owned by the effective group ID

       uid    files  owned  by  user ID id if that is a number.  Otherwise, id
              specifies a user name: the character after the `u' will be taken
              as  a  separator and the string between it and the next matching
              separator will be taken as a user name.  The starting separators
              `[',  `{', and `<' match the final separators `]', `}', and `>',
              respectively; any other character matches itself.  The  selected
              files  are  those  owned by this user.  For example, `u:foo:' or
              `u[foo]' selects files owned by user `foo'.

       gid    like uid but with group IDs or names

       a[Mwhms][-|+]n
              files accessed exactly n days ago.  Files  accessed  within  the
              last  n  days  are  selected  using a negative value for n (-n).
              Files accessed more than n days ago are selected by a positive n
              value  (+n).  Optional unit specifiers `M', `w', `h', `m' or `s'
              (e.g. `ah5') cause the check to be performed with months (of  30
              days), weeks, hours, minutes or seconds instead of days, respec-
              tively.  An explicit `d' for days is also allowed.

              Any fractional part of the difference between  the  access  time
              and  the current part in the appropriate units is ignored in the
              comparison.  For  instance,  `echo  *(ah-5)'  would  echo  files
              accessed  within the last five hours, while `echo *(ah+5)' would
              echo files accessed at least six hours ago,  as  times  strictly
              between five and six hours are treated as five hours.

       m[Mwhms][-|+]n
              like  the  file  access  qualifier, except that it uses the file
              modification time.

       c[Mwhms][-|+]n
              like the file access qualifier, except that  it  uses  the  file
              inode change time.

       L[+|-]n
              files less than n bytes (-), more than n bytes (+), or exactly n
              bytes in length.

              If this flag is directly followed by a size specifier `k' (`K'),
              `m'  (`M'),  or  `p' (`P') (e.g. `Lk-50') the check is performed
              with kilobytes, megabytes, or blocks  (of  512  bytes)  instead.
              (On  some  systems additional specifiers are available for giga-
              bytes, `g' or `G', and terabytes, `t' or `T'.) If a size  speci-
              fier  is  used  a  file is regarded as "exactly" the size if the
              file size rounded up to the next unit is equal to the test size.
              Hence `*(Lm1)' matches files from 1 byte up to 1 Megabyte inclu-
              sive.  Note also that the set of files "less than" the test size
              only  includes  files  that  would  not match the equality test;
              hence `*(Lm-1)' only matches files of zero size.

       ^      negates all qualifiers following it

       -      toggles between making the qualifiers  work  on  symbolic  links
              (the default) and the files they point to

       M      sets the MARK_DIRS option for the current pattern

       T      appends a trailing qualifier mark to the filenames, analogous to
              the LIST_TYPES option, for the current pattern (overrides M)

       N      sets the NULL_GLOB option for the current pattern

       D      sets the GLOB_DOTS option for the current pattern

       n      sets the NUMERIC_GLOB_SORT option for the current pattern

       Yn     enables short-circuit mode: the pattern will expand to at most n
              filenames.   If  more  than  n  matches  exist, only the first n
              matches in directory traversal order will be considered.

              Implies oN when no oc qualifier is used.

       oc     specifies how the names of the files should be sorted. If c is n
              they are sorted by name; if it is L they are sorted depending on
              the size (length) of the files; if l they are sorted by the num-
              ber  of  links; if a, m, or c they are sorted by the time of the
              last access, modification, or inode change respectively;  if  d,
              files  in  subdirectories  appear  before  those  in the current
              directory at each level of the search -- this is  best  combined
              with  other  criteria,  for  example `odon' to sort on names for
              files within the same directory; if N, no sorting is  performed.
              Note  that a, m, and c compare the age against the current time,
              hence the first name in the list is the youngest file. Also note
              that  the  modifiers ^ and - are used, so `*(^-oL)' gives a list
              of all files sorted by file size in descending order,  following
              any  symbolic  links.   Unless oN is used, multiple order speci-
              fiers may occur to resolve ties.

              The default sorting is n (by name) unless the Y  glob  qualifier
              is used, in which case it is N (unsorted).

              oe  and  o+  are  special cases; they are each followed by shell
              code, delimited as for the e glob qualifier and the + glob qual-
              ifier  respectively  (see above).  The code is executed for each
              matched file with the parameter REPLY set to  the  name  of  the
              file  on  entry  and globsort appended to zsh_eval_context.  The
              code should modify the parameter  REPLY  in  some  fashion.   On
              return,  the  value of the parameter is used instead of the file
              name as the string on which to sort.  Unlike other  sort  opera-
              tors,  oe and o+ may be repeated, but note that the maximum num-
              ber of sort operators of any kind that may appear  in  any  glob
              expression is 12.

       Oc     like  `o',  but  sorts in descending order; i.e. `*(^oc)' is the
              same as `*(Oc)' and `*(^Oc)' is the same as `*(oc)';  `Od'  puts
              files in the current directory before those in subdirectories at
              each level of the search.

       [beg[,end]]
              specifies which of the matched filenames should be  included  in
              the  returned  list.  The  syntax  is the same as for array sub-
              scripts. beg and the optional end may  be  mathematical  expres-
              sions. As in parameter subscripting they may be negative to make
              them count from the last  match  backward.  E.g.:  `*(-OL[1,3])'
              gives a list of the names of the three largest files.

       Pstring
              The  string  will  be prepended to each glob match as a separate
              word.  string is delimited in the same way as arguments to the e
              glob  qualifier described above.  The qualifier can be repeated;
              the words are prepended separately so that the resulting command
              line contains the words in the same order they were given in the
              list of glob qualifiers.

              A typical use for this is to prepend an option before all occur-
              rences  of a file name; for example, the pattern `*(P:-f:)' pro-
              duces the command line arguments `-f file1 -f file2 ...'

              If the modifier ^  is  active,  then  string  will  be  appended
              instead of prepended.  Prepending and appending is done indepen-
              dently so both can be used on  the  same  glob  expression;  for
              example  by writing `*(P:foo:^P:bar:^P:baz:)' which produces the
              command line arguments `foo baz file1 bar ...'

       More than one of these lists can be combined, separated by commas.  The
       whole  list  matches  if at least one of the sublists matches (they are
       `or'ed, the qualifiers in the sublists are `and'ed).  Some  qualifiers,
       however,  affect  all  matches generated, independent of the sublist in
       which they are given.  These are the qualifiers  `M',  `T',  `N',  `D',
       `n', `o', `O' and the subscripts given in brackets (`[...]').

       If  a  `:' appears in a qualifier list, the remainder of the expression
       in parenthesis is interpreted as a modifier  (see  the  section  `Modi-
       fiers'  in  the  section  `History  Expansion').  Each modifier must be
       introduced by a separate `:'.  Note also that the result after  modifi-
       cation  does not have to be an existing file.  The name of any existing
       file can be followed by a modifier of the  form  `(:...)'  even  if  no
       actual  filename  generation is performed, although note that the pres-
       ence of the parentheses causes the entire expression to be subjected to
       any global pattern matching options such as NULL_GLOB. Thus:

              ls *(-/)

       lists all directories and symbolic links that point to directories, and

              ls *(-@)

       lists all broken symbolic links, and

              ls *(%W)

       lists all world-writable device files in the current directory, and

              ls *(W,X)

       lists  all  files  in  the current directory that are world-writable or
       world-executable, and

              echo /tmp/foo*(u0^@:t)

       outputs the basename of all root-owned files beginning with the  string
       `foo' in /tmp, ignoring symlinks, and

              ls *.*~(lex|parse).[ch](^D^l1)

       lists  all  files  having a link count of one whose names contain a dot
       (but not those starting with  a  dot,  since  GLOB_DOTS  is  explicitly
       switched off) except for lex.c, lex.h, parse.c and parse.h.

              print b*.pro(#q:s/pro/shmo/)(#q.:s/builtin/shmiltin/)

       demonstrates  how  colon  modifiers and other qualifiers may be chained
       together.  The ordinary qualifier `.' is applied first, then the  colon
       modifiers  in order from left to right.  So if EXTENDED_GLOB is set and
       the base pattern matches the regular file builtin.pro, the  shell  will
       print `shmiltin.shmo'.



zsh 5.6.2                     September 14, 2018                    ZSHEXPN(1)