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ZSHEXPN(1)                                                          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 zsh-
              misc(1).

       Process Substitution
       Parameter Expansion
       Command Substitution
       Arithmetic Expansion
       Brace Expansion
              These five are performed in one step in left-to-right fashion.  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 expansion, 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 corrections 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 parame-
       ter.  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 command line; history expansions do not nest.  The '!' can be escaped with '\' or can
       be  enclosed between a pair of single quotes ('') to suppress its special meaning.  Double quotes will not work
       for this.  Following this history character is an optional event designator (see the  section  'Event  Designa-
       tors')  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.

       By default, a history reference with no event designator refers to the same event as any preceding history ref-
       erence  on  that command line; if it is the only history reference in a command, it refers to the previous com-
       mand.  However, if the option CSH_JUNKIE_HISTORY is set, then every history reference with no event  specifica-
       tion 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 '!!$' always refers to the last word of the previous command.   With  CSH_JUNKIE_HIS-
       TORY  set,  then  '!:1' and '!$' 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
       previous 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, replacing the string foo with bar.  More precisely, the sequence '^foo^bar^' is syn-
       onymous with '!!:s^foo^bar^', hence other modifiers (see the section '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  subse-
       quent '!' characters have no special significance.

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

   Event Designators
       An  event  designator  is a reference to a command-line entry in the history 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, newline, '=' or '('.   If  followed  immedi-
              ately  by a word designator (see the section 'Word Designators'), this forms a history reference 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 modifier 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 necessary).

   Word Designators
       A word designator indicates which word or words of a given command line are to be included in a history  refer-
       ence.  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 pre-
       ceded by a ':'.  These modifiers 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, and resolves  any
              use  of  '..'  and  '.'  in  the path.  Note that the transformation takes place even if the file or any
              intervening directories do not exist.

       A      As 'a', but also resolve use of symbolic links where possible.  Note  that  resolution  of  '..'  occurs
              before  resolution  of symbolic links.  This call is equivalent to a unless your system has the realpath
              system call (modern systems do).

       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 extension.

       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.

       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 of the form '.xxx', leaving the root name.

       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 delim-
       iter 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  immediately
       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 qualifers an extra backslash is needed as a & is a special character  in
       this case.

       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  complicated  patterns
       used  in  globbing  qualifiers  may  need the extended glob qualifier notation (#q:s/.../.../) in order for the
       shell to recognize the expression as a glob qualifier.  Further, note that bad patterns 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  pattern  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 sub-
       stitution 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 generation.

       The following f, F, w and W modifiers work only with parameter expansion 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 evaluates 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 expression may be preceeded or followed by other strings except  that,  to  prevent  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.

       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 system 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 com-
       mand argument will be a named pipe.  If the form with > is selected then writing on this special file will pro-
       vide  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 argument 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  substitu-
       tions have been performed.  This is handled entirely within the current 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 implementation 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  run-
       ning  setuid.  In the second case, if the programme does not actually open the file, the subshell attempting to
       read from or write to the pipe will (in a typical implementation, different operating systems may have  differ-
       ent behaviour) block for ever and have to be killed explicitly.  In both cases, the shell actually supplies the
       information using a pipe, so that programmes that expect to lseek (see lseek(2)) on the file will not work.

       Also note that the previous example can be more compactly and efficiently 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  con-
       cerned.  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.


PARAMETER EXPANSION
       The  character '$' is used to introduce parameter expansions.  See zshparam(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 replace-
       ment text of any substitutions, are themselves subject to parameter expansion, command substitution, and arith-
       metic  expansion.  In addition to the following operations, the colon modifiers described in the section 'Modi-
       fiers' in the section 'History Expansion' can be applied:  for example, ${i:s/foo/bar/} performs string substi-
       tution on the expansion of parameter $i.

       ${name}
              The value, if any, of the parameter name is substituted.  The braces are required if the expansion is to
              be followed by a letter, digit, or underscore that is not to be interpreted as part of name.   In  addi-
              tion, 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 subscript 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, otherwise '0' is substituted.

       ${name-word}
       ${name:-word}
              If name is set, or in the second form is non-null, then substitute 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 substitute 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  substi-
              tute its value; otherwise, print word and exit from the shell.  Interactive shells instead return to the
              prompt.  If word is omitted, then a standard message 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 substitution 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 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}
              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:offset}
       ${name:offset:length}
              This syntax gives effects similar to parameter subscripting in the form $name{start,end}, but is compat-
              ible 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 substitute elements  starting
              offset  elements  from  the  first element.  If length is given, substitute that many characters or ele-
              ments, 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 char-
              acter 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.

              length  is  always  treated directly as a length and hence may not be negative.  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 substu-
              tion 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  modi-
              fiers.   To  substitute  a  value from a variable, the recommended approach is to proceed it with a $ as
              this signifies the intention (parameter 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  to the first element of the array.  However, if the substitution refers the positional parame-
              ter 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} substitutes $1.

       ${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.  Both pattern and repl
              are subject to double-quoted substitution, so that expressions like ${name/$opat/$npat} will  work,  but
              note  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 pattern 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.

              The  first  '/'  may  be  preceded by a ':', in which case the match will only succeed if it matches the
              entire word.  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 pattern 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.
              Note that '^', '=', and '~', below, must appear to the left of '#' when these forms are combined.

       ${^spec}
              Turn on the RC_EXPAND_PARAM option for the evaluation of spec; if the '^' is doubled, turn it off.  When
              this option is set, array expansions of the form foo${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 section 'Brace Expansion'
              below.  If word splitting is also in effect the $var[N] may themselves be split into different list ele-
              ments.

       ${=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 surrounding 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
              filename  generation,  but  ${${~foo}//\*/*.c}  substitutes to the string *.c, which will not be further
              expanded.

       If a ${...} type parameter expression or a $(...) type command substitution 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 $(foo), but the flag  '(f)'  (see  below)  is  applied
       using  the  rules for unquoted expansions.  Note further that quotes are themselves nested in this context; for
       example, in "${(@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  repetitions
       need  not be consecutive; for example, '(q%q%q)' means the same thing as the more readable '(%%qqq)'.  The fol-
       lowing flags are supported:

       #      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 the f, s or z flags, which still applies within each array element.

       A      Create an array parameter with '${...=...}', '${...:=...}' or '${...::=...}'.  If this flag is  repeated
              (as in 'AA'), create an associative array parameter.  Assignment is made before sorting or padding.  The
              name part may be a subscripted range for ordinary arrays; the word part must be converted to  an  array,
              for example by using '${(AA)=name=...}' to activate field splitting, when creating an associative array.

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

       c      With ${#name}, count the total number of characters in an array, as if the  elements  were  concatenated
              with spaces between them.

       C      Capitalize  the  resulting  words.   'Words' in this case refers to sequences of alphanumeric characters
              separated by non-alphanumerics, 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 subsituted) is
              then quoted so that the whole string can be used as a shell  argument.   This  is  the  reverse  of  '~'
              substitution:  see the section FILENAME EXPANSION below.

       e      Perform  parameter  expansion,  command substitution and arithmetic expansion on the result. Such expan-
              sions can be nested but too deep recursion may have unpredictable effects.

       f      Split the result of the expansion at newlines. This is a shorthand for 'ps:\n:'.

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

       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 values.  However, this flag may  not  be  combined  with  subscript
              ranges.

       L      Convert all letters in the result to lower case.

       n      Sort decimal integers numerically; if the first differing characters 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 appropriate.  Note that flags set with one of the typeset family of commands (in par-
              ticular 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'.

       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.

       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  consists 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  key-
              words 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 duplicated values

              hide   for parameters with the 'hide' 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 subscripts, 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_COMMENTS option unset.

              Note that this is done very late, as for the '(s)' flag. So to access single words in  the  result,  one
              has  to  use  nested expansions as in '${${(z)foo}[2]}'. Likewise, to remove the quotes in the resulting
              words one would do: '${(Q)${(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 delimiters 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.

       ~      Force  string  arguments  to  any of the flags below that follow within the parentheses to be treated as
              patterns.  Compare with a ~ outside parentheses, which  forces  the  entire  substituted  string  to  be
              treated as a pattern.  Hence, for example,
              [[ "?" = ${(~j.|.)array} ]]
       with  the  EXTENDED_GLOB  option set succeeds if and only if $array contains the string '?' as an element.  The
       argument 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 truncated 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 delimiters 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  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 gen-
              erating 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 certain 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 separate characters),
              except for the case where combining characters themselves have non-zero width (true  in  certain  alpha-
              bets).

       r:expr::string1::string2:
              As  l,  but  pad  the words on the right and insert string2 immediately 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 padding 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.

              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 following pair of delimiter characters.  (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  ordi-
              nary whitespace, else they are treated as if they are shell code delimiters and converted to semicolons.

       _: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 longest match should be replaced.

       I:expr:
              Search  the  exprth match (where expr evaluates to a number).  This only applies when searching for sub-
              strings, either with the S  flag,  or  with  ${.../...}  (only  the  exprth  match  is  substituted)  or
              ${...//...} (all matches from the exprth on are substituted).  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  replacements  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 forward 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 of the end of the match in the result.

       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 particular examples are given below.  Note that the Zsh Development Group accepts no respon-
       sibility 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 substitution 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  substi-
              tution,  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 substitution; for example, the expansion ${${foo}} behaves exactly
              the same as ${foo}.

              At each nested level of substitution, the substituted words undergo all forms of  single-word  substitu-
              tion  (i.e.  not filename generation), including command substitution, arithmetic expansion 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 filename 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 commands, in particular the L, R, Z, u and l
              flags for padding and capitalization, are applied directly to the parameter value.

       3. Parameter Subscripting
              If the value is a raw parameter reference with a subscript, such as ${var[3]}, the effect of  subscript-
              ing is applied directly to the parameter.  Subscripts are evaluated left to right; subsequent 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.

       4. Parameter Name Replacement
              The  effect  of any (P) flag, which treats the value so far as a parameter name and replaces it with the
              corresponding value, is applied.

       5. Double-Quoted Joining
              If the value after this process is an array, and the substitution appears in double quotes, and  no  (@)
              flag  is present at the current level, the words of the value are joined with the first character of the
              parameter $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 '#', '%', '/' (possibly 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 numerically 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
              rules  16. or 17., and joining did not take place at step 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 sup-
              plies a string for joining in this manner.

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

       12. Prompt evaluation
              Any prompt-style formatting from the (%) family of flags is applied.

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

       14. Directory naming
              Any directory name substitution using (D) flag is applied.

       15. Visibility enhancment
              Any modifications to make characters visible using the (V) flag are applied.

       16. Forced Splitting
              If  one of the '(s)', '(f)' or '(z)' flags are present, or the '=' specifier was present (e.g. ${=var}),
              the word is split on occurrences of the specified string, or (for  =  with  neither  of  the  two  flags
              present) any of the characters in $IFS.

       17. Shell Word Splitting
              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 occurrences of any of the characters in $IFS.  Note this step, too, takes place at  all
              levels of a nested substitution.

       18. Uniqueness
              If the result is an array and the '(u)' flag was present, duplicate 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. Re-Evaluation
              Any  '(e)'  flag  is applied to the value, forcing it to be re-examined for new parameter substitutions,
              but also for command and arithmetic substitutions.

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

       22. 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.

       23. Empty argument removal
              If the substitution does not appear in double quotes, any resulting zero-length argument, whether from a
              scalar or an element 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 simply that it occurs after any of the above parameter operations.


   Examples
       The flag f is useful to split a double-quoted substitution line by line.  For example, ${(f)"$(<file)"} substi-
       tutes  the  contents of file divided so that each line is an element of the resulting array.  Compare this with
       the effect of $(<file) alone, which divides the file up by words, or the same inside double quotes, which makes
       the entire content 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 "${foo}", which has no array (@)  flag,  pro-
              duces  a  single  word  result  "bar baz".  The outer substitution "${(@)...[1]}" detects that this is a
              scalar, so that (despite the '(@)' flag) the subscript picks the first character.

       "${${(@)foo}[1]}"
              This produces the result 'bar'.  In this case, the inner substitution  "${(@)foo}"  produces  the  array
              '(bar baz)'.  The outer substitution "${...[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  split-
              ting,  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 '$(...)', or quoted with grave accents, like
       ''...'', is replaced with its standard output, with any trailing newlines deleted.  If the substitution is  not
       enclosed  in  double  quotes, the output is broken into words using the IFS parameter.  The substitution '$(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 generation.

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  leading
       zeroes  to  that minimum width, but for negative numbers the - character 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).

       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 nor-
       mally.  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 (globbing); an expression such as  */{foo,bar}  is
       split into two separate words */foo and */bar before filename generation takes place.  In particular, 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 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
       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
       The feature described here is only available if the shell function zsh_directory_name exists.

       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 state-
       ment 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 and NOMATCH handling is
       applied if the option is set.

       The function zsh_directory_name is 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 the function is passed two argu-
       ments: 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  prefix  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  func-
       tion 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.

       The  completion  system  calls  'zsh_directory_name c' 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  under-
       score  ('_'),  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.

       In  certain  circumstances (in prompts, for instance), when the shell prints a path, 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 shortest way of referring to the directory is used, with ties broken in favour
       of using a named directory, except when the directory is / itself.  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 behaviour can be disabled by quoting the '~', the '=', or the whole expression  (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; otherwise 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 generation  pattern
       matches  the  files  '.' or '..'.  In other instances of pattern matching, the '/' and '.' are not treated spe-
       cially.

   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 charac-
              ters  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 either space or tab

              [:cntrl:]
                     The character is a control character

              [:digit:]
                     The character is a decimal digit

              [:graph:]
                     The character is a printable character other than whitespace

              [: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 identifier, 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.

              [: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 alphanumeric 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  actu-
              ally  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
              consequence  of  the  rule  that  the  longest  possible  match  always  succeeds.   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.

       ^x     (Requires  EXTENDED_GLOB  to  be set.)  Matches anything except the pattern x.  This has a higher prece-
              dence 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 occurrences 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  followed  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 occurrences 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 modified 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 '(...)#'.)

       +(...) Match at least one occurrence.  (Like '(...)##'.)

       ?(...) 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 directory 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  fol-
       lowing 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  genera-
              tion.  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  $mbe-
              gin,  and  the indices of the end in the array $mend, with the first element 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  consid-
              ered 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 back-
              reference.

              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 substitution, 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  paren-
              theses  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 alter-
              nate 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; 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 specifying 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  pattern,  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  substi-
              tutions, 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, printing 'vEldt jynx grImps wAqf zhO bUck'.

              Unlike  backreferences,  there is no speed penalty for using match references, other than the extra sub-
              stitutions 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 reg-
              ular expressions.  They are useful for matching path segments in patterns other than those  in  filename
              generation   (where   path   segments   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 actually 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 globbing 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 useful 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 multibyte 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 Uni-
              code 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 MULTI-
              BYTE 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-insensi-
       tively 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 speci-
       fied 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  sec-
       ond once, grouping the string as [d][cb][a] and [a][bc][d].

       Non-literal  parts  of the pattern must match exactly, including characters 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 character).  Similarly, errors are counted separately for non-contigu-
       ous 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  pat-
       tern 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  approxima-
       tion; for example, (#a1)abc(#a0)xyz will not match abcdxyz, because the error occurs at the 'x', where approxi-
       mation 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 segment.  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
       segments 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 therefore 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 otherwise iden-
       tical.   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.

   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 qualifiers 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 recognised 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.

       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)

       %      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 num-
              ber describes the mode bits to be expected, if combined 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  charac-
              ters  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 status (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 separator will be taken  as the string; '[', '{', and '<' match ']', '}', and '>', respec-
              tively, 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 execution.

              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 lonely2' to be inserted into  the  command
              line.  Note the quotation marks.

              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, respectively.

              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 'k' ('K'), 'm' ('M'), or 'p' ('P') (e.g. 'Lk-50') the check is
              performed with kilobytes, megabytes, or blocks (of 512 bytes) instead.  In this case 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 inclusive.  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

       oc     specifies  how the names of the files should be sorted. If c is n they are sorted by name (the default);
              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 specifiers may occur to resolve
              ties.

              oe and o+ are special cases; they are each followed by shell code, delimited as for the e glob qualifier
              and  the + glob qualifier 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 operators, oe and o+ may  be
              repeated,  but  note  that  the maximum number 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 subscripts. beg and the optional end may be mathematical expressions. As in parameter sub-
              scripting 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 occurrences of a file name; for  example,  the
              pattern '*(P:-f:)' produces the command line arguments '-f file1 -f file2 ...'

       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  modi-
       fier  (see  the section 'Modifiers' in the section 'History Expansion').  Each modifier must be introduced by a
       separate ':'.  Note also that the result after modification 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 presence 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 *(%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 4.3.11                     December 20, 2010                    ZSHEXPN(1)