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ZSHEXPN(1)							    ZSHEXPN(1)

NAME
       zshexpn - zsh expansion and substitution

DESCRIPTION
       The types of expansions performed are

       History Expansion
       Alias Expansion
       Process Substitution
       Parameter Expansion
       Command Substitution
       Arithmetic Expansion
       Brace Expansion
       Filename Expansion
       Filename Generation

       Expansion  is  done  in	the  above specified order in five steps.  The
       first is history expansion, which  is  only  performed  in  interactive
       shells.	 The  next step is alias expansion, which is done right before
       the command line is parsed.  They are followed by process substitution,
       parameter  expansion,  command  substitution,  arithmetic expansion and
       brace expansion which are performed in one step in left-to-right	 fash‐
       ion.   After  these expansions, all unquoted occurrences of the charac‐
       ters `\', `'' and `"' are removed, and the result is subjected to file‐
       name expansion followed by filename generation.

       If the SH_FILE_EXPANSION option is set, the order of expansion is modi‐
       fied for compatibility with sh and ksh.	 Filename  expansion  is  per‐
       formed  immediately  after  alias  expansion, preceding the set of five
       expansions mentioned above.

HISTORY EXPANSION
       History expansion allows you to use words from previous	command	 lines
       in  the	command line you are typing.  This simplifies spelling correc‐
       tions and the repetition of complicated commands or arguments.  Immedi‐
       ately  before execution, each command is saved in the history list, the
       size of which is controlled by the HISTSIZE parameter.	The  one  most
       recent  command	is always retained in any case.	 Each saved command in
       the history list is called a history event and is  assigned  a  number,
       beginning  with	1  (one) when the shell starts up.  The history number
       that you may see in your prompt (see the section `Prompt Expansion') is
       the number that is to be assigned to the next command.

   Overview
       A  history  expansion  begins with the first character of the histchars
       parameter, which is `!' by default, and may occur anywhere on the  com‐
       mand line; 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  Designators') and then an optional word designator (the section
       `Word Designators'); if neither of these	 designators  is  present,  no
       history expansion occurs.

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

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

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

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

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

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

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

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

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

       !n     Refer to command-line n.

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

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

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

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

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

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

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

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

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

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

       r      Remove a filename extension of the form `.xxx', leaving the root
	      name.

       e      Remove all but the extension.

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

       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.

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

       l      Convert the words to all lowercase.

       u      Convert the words to all uppercase.

       s/l/r[/]
	      Substitute r for l as described below.  Unless preceded  immedi‐
	      ately  by	 a  g, with no colon between, 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.

       &      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.

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

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

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

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

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

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

PROCESS SUBSTITUTION
       Each command argument of the form `<(list)', `>(list)' or `=(list)'  is
       subject	to process substitution.  In the case of the < or > forms, the
       shell runs process list asynchronously.	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 command argument will be a named pipe.	If the
       form with > is selected then writing on this special file will  provide
       input for list.	If < is used, then the file passed as an argument will
       be connected to the output of the list process.	For example,

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

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

       Both the /dev/fd and the named pipe implementation have drawbacks.   In
       the  former  case,  some	 programmes  may  automatically close the file
       descriptor in question before examining the file on the	command	 line,
       particularly if this is necessary for security reasons such as when the
       programme is running setuid.  In the second  case,   if	the  programme
       does not actually open the file the subshell attempting to read from or
       write to the pipe will (in a typical implementation, different  operat‐
       ing systems may have different 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	 effi‐
       ciently written (provided the MULTIOS option is set) as:

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

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

       If = is used, 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.

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

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

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

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

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

       ${name:-word}
	      If name is set and is non-null then substitute its value; other‐
	      wise substitute word. If name is missing, substitute word.

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

       ${name:?word}
	      If name is set and is non-null then substitute its value; other‐
	      wise,  print  word  and exit from the shell.  Interactive shells
	      instead return to the prompt.  If word is omitted, then a	 stan‐
	      dard message is printed.

       ${name:+word}
	      If  name	is set and is non-null then substitute word; otherwise
	      substitute nothing.

       If the colon is omitted from one of the above expressions containing  a
       colon,  then the shell only checks whether name is set, not whether its
       value is null.

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

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

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

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

       ${name/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.	 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  two
	      backslashes (i.e., a quoted 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 substi‐
	      tuted 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 pat‐
	      tern rather than a plain string.	In the first case, the longest
	      match for t*e is substituted and the result is `spy star', while
	      in the second case, the  shortest	 matches  are  taken  and  the
	      result is `spy spy lispy star'.

       ${#spec}
	      If spec is one of the above substitutions, substitute the length
	      in characters of the result instead of the  result  itself.   If
	      spec  is	an array expression, substitute the number of elements
	      of the result.  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'.

	      Internally, each such expansion is converted into the equivalent
	      list   for   brace    expansion.	   E.g.,    ${^var}    becomes
	      {$var[1],$var[2],...}, and is processed as described in the sec‐
	      tion `Brace Expansion' below.  If	 word  splitting  is  also  in
	      effect  the  $var[N] may themselves be split into different list
	      elements.

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

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

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

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

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

   Parameter Expansion Flags
       If  the	opening	 brace is directly followed by an opening parenthesis,
       the string up to the matching closing parenthesis will be  taken	 as  a
       list of flags.  Where arguments are valid, any character, or the match‐
       ing pairs `(...)', `{...}', `[...]', or `<...>',	 may be used in	 place
       of the colon as delimiters.  The following flags are supported:

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

       @      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]"'.

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

       P      This forces the value of the parameter name to be interpreted as
	      a further parameter name, whose value will be used where	appro‐
	      priate. 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'.

       o      Sort the resulting words in ascending order.

       O      Sort the resulting words in descending order.

       i      With o or O, sort case-independently.

       L      Convert all letters in the result to lower case.

       U      Convert all letters in the result to upper case.

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

       V      Make any special characters in the resulting words visible.

       q      Quote  the  resulting  words  with  backslashes. 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. If it is given four times, the words are quoted in  sin‐
	      gle quotes preceded by a $.

       Q      Remove one level of quotes from the resulting words.

       %      Expand  all  % escapes in the resulting words in the same way as
	      in prompts (see the section `Prompt Expansion'). 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.

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

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

       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.

       k      If name refers to an  associative	 array,	 substitute  the  keys
	      (element	names)	rather	than the values of the elements.  Used
	      with subscripts (including ordinary arrays),  force  indices  or
	      keys to be substituted even if the subscript form refers to val‐
	      ues.  However, this flag may  not	 be  combined  with  subscript
	      ranges.

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

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

       l:expr::string1::string2:
	      Pad  the	resulting  words on the left.  Each word will be trun‐
	      cated if required and placed in a field  expr  characters	 wide.
	      The  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,  this string is inserted once
	      directly to the left of each word, before padding.

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

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

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

       s:string:
	      Force field splitting (see the option SH_WORD_SPLIT) at the sep‐
	      arator  string.	Splitting only occurs in places where an array
	      value is valid.

       f      Split the result of the expansion to lines. This is a  shorthand
	      for `ps:\n:'.

       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.

	      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	expan‐
	      sions as in `${${(z)foo}[2]}'. Likewise, to remove the quotes in
	      the resulting words one would do: `${(Q)${(z)foo}}'.

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

	      local  for local parameters

	      left   for left justified parameters

	      right_blanks
		     for right justified parameters with leading blanks

	      right_zeros
		     for right justified parameters with leading zeros

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

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

	      readonly
		     for readonly parameters

	      tag    for tagged parameters

	      export for exported parameters

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

	      hide   for parameters with the `hide' flag

	      special
		     for special parameters defined by the shell

       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 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 substrings, either with the
	      S flag, or with ${.../...} (only the  exprth  match  is  substi‐
	      tuted)  or  ${...//...} (all matches from the exprth on are sub‐
	      stituted).  The 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.

       M      Include the matched portion in the result.

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

       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.

       N      Include the length of the match in the result.

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

       1. Nested Substitution
	      If  multiple  nested  ${...}  forms are present, substitution is
	      performed from the inside outwards.  At each level, the  substi‐
	      tution takes account of whether the current value is a scalar or
	      an array, whether the whole substitution is  in  double  quotes,
	      and  what	 flags	are supplied to the current level of substitu‐
	      tion, just as if the nested  substitution	 were  the  outermost.
	      The  flags are not propagated up to enclosing substitutions; the
	      nested substitution will return either a scalar or an  array  as
	      determined by the flags, possibly adjusted for quoting.  All the
	      following steps take place where applicable  at  all  levels  of
	      substitution.   Note that, unless the `(P)' flag is present, the
	      flags and any subscripts apply directly  to  the	value  of  the
	      nested   substitution;  for  example,  the  expansion  ${${foo}}
	      behaves exactly the same as ${foo}.

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

       3. 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.

       4. Double-Quoted Joining
	      If the value after this process is an array, and	the  substitu‐
	      tion 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.

       5. 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 2., 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).

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

       7. 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 8. or 9., and join‐
	      ing did not take place at step 4., any words in  the  value  are
	      joined together using the given string or the first character of
	      $IFS if none.  Note that the `(F)' flag  implicitly  supplies  a
	      string for joining in this manner.

       8. 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.

       9. 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 occur‐
	      rences of any of the characters in $IFS.	Note this  step,  too,
	      takes place at all levels of a nested substitution.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       If  a  brace  expression	 matches  none	of the above forms, it is left
       unchanged, unless the BRACE_CCL option is set.  In  that	 case,	it  is
       expanded	 to  a	sorted	list  of the individual characters between the
       braces, in the manner of a search set.  `-' is treated specially as  in
       a  search  set,	but  `^' or `!' as the first character is treated nor‐
       mally.

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

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 the value of $PWD or $OLDPWD, respectively.

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

       A  `~' followed by anything not already covered 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 sys‐
       tem.  They may also be defined if the text after the `~' is the name of
       a  string  shell	 parameter  whose value begins with a `/'.  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.

       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 or alias.  If a
       command	exists by that name, the word is replaced by the full pathname
       of the command.	If an alias exists by that name, the word is  replaced
       with the text of the alias.

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

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

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

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

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

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

       ?      Matches any character.

       [...]  Matches any of the enclosed characters.	Ranges	of  characters
	      can  be  specified by separating two characters by a `-'.	 A `-'
	      or `]' may be matched by including it as the first character  in
	      the  list.   There are also several named classes of characters,
	      in the form `[:name:]' with the following meanings:  `[:alnum:]'
	      alphanumeric,  `[:alpha:]' alphabetic, `[:blank:]' space or tab,
	      `[:cntrl:]'  control  character,	`[:digit:]'   decimal	digit,
	      `[:graph:]'  printable  character except whitespace, `[:lower:]'
	      lowercase letter, `[:print:]' printable  character,  `[:punct:]'
	      printable	  character   neither	alphanumeric  nor  whitespace,
	      `[:space:]' whitespace character, `[:upper:]' uppercase  letter,
	      `[:xdigit:]'  hexadecimal	 digit.	 These use the macros provided
	      by the operating system to test for the given character combina‐
	      tions,  including	 any  modifications due to local language set‐
	      tings:  see ctype(3).  Note that the square brackets  are	 addi‐
	      tional  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 actually match any number
	      whatsoever at the start of the string, since  the	 `<0-9>'  will
	      match  the first digit, and the `*' will match any others.  This
	      is a trap for the unwary, but is in fact	an  inevitable	conse‐
	      quence  of  the rule that the longest possible match always suc‐
	      ceeds.  Expressions such as  `<0-9>[^[:digit:]]*'	 can  be  used
	      instead.

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

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

       x|y    Matches either x or y.  This operator has lower precedence  than
	      any  other.   The	 `|'  character must be within parentheses, to
	      avoid interpretation as a pipeline.

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

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

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

       x##    (Requires EXTENDED_GLOB to be set.)  Matches one or more	occur‐
	      rences  of  the  pattern	x.  This operator has high precedence;
	      `12##' is equivalent to `1(2##)', rather than `(12)##'.  No more
	      than two active `#' characters may appear together.

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

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

       *(...) Match any number of occurrences.	(Like `(...)#'.)

       +(...) 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	direc‐
       tory  separator	may not appear inside parentheses, while a `|' must do
       so; in patterns used in other contexts than  filename  generation  (for
       example,	 in  case statements and tests within `[[...]]'), a `/' is not
       special; and `/' is also not special  after  a  `~'  appearing  outside
       parentheses in a filename pattern.

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

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

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

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

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

	      For example,

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

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

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

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

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

	      Pattern matching with backreferences  is	slightly  slower  than
	      without.

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

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

	      For example,

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

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

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

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

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

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

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

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

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

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

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

       1.     Different characters, as in fooxbar and fooybar.

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

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

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

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

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

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

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

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

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

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

	      ls (*/)#bar

       or

	      ls **/bar

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

   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))'.

       A qualifier may be any one of the following:

       /      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 number describes the mode bits to be expected, if com‐
	      bined  with  a  `=',  the	 value given must match the file-modes
	      exactly, with a `+', at least the bits in the given number  must
	      be set in the file-modes, and with a `-', the bits in the number
	      must not be set. Giving a `?' instead of a octal digit  anywhere
	      in  the  number  ensures	that  the  corresponding  bits	in the
	      file-modes are not checked, this is only useful  in  combination
	      with `='.

	      If the qualifier `f' is followed by any other character anything
	      up to the next matching character (`[', `{', and `<' match  `]',
	      `}',  and	 `>' respectively, any other character matches itself)
	      is taken as a list of comma-separated sub-specs.	Each  sub-spec
	      may be either a 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 a octal  digit.  The  first  list  of
	      characters  specify  which access rights are to be checked. If a
	      `u' is given, those for the owner of the file are used, if a `g'
	      is  given,  those	 of the group are checked, a `o' means to test
	      those of other users, and the `a' says to test all three groups.
	      The `=', `+', and `-' again says how the modes are to be checked
	      and have the same meaning as described for the first form above.
	      The  second  list of characters finally says which access rights
	      are to be expected: `r' for read access, `w' for	write  access,
	      `x'  for	the  right  to execute the file (or to search a direc‐
	      tory), `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
	      The string will be executed as shell code.  The filename will be
	      included in the list if and only if the code returns a zero sta‐
	      tus (usually the status of the last command).  The first charac‐
	      ter 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 `>', respectively, while any
	      other character matches itself. Note  that  expansions  must  be
	      quoted  in the string to prevent them from being expanded before
	      globbing is done.

	      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.

       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 it is a number, if  not,  than  the
	      character	 after	the  `u'  will	be used as a separator and the
	      string between it and the next matching separator (`[', `{', and
	      `<'  match  `]',	`}', and `>' respectively, any other character
	      matches itself) will be taken as a user name, and the user ID of
	      this  user  will	be  taken  (e.g. `u:foo:' or `u[foo]' for user
	      `foo')

       gid    like uid but with group IDs or names

       a[Mwhms][-|+]n
	      files accessed exactly n days ago.  Files	 accessed  within  the
	      last  n  days  are  selected  using a negative value for n (-n).
	      Files accessed more than n days ago are selected by a positive n
	      value  (+n).  Optional unit specifiers `M', `w', `h', `m' or `s'
	      (e.g. `ah5') cause the check to be performed with months (of  30
	      days), weeks, hours, minutes or seconds instead of days, respec‐
	      tively.  For instance, `echo *(ah-5)' would echo files  accessed
	      within the last 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 per‐
	      formed with kilobytes,  megabytes,  or  blocks  (of  512	bytes)
	      instead.

       ^      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 number 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.  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.

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

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

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

       If a `:' appears in a qualifier list, the remainder of  the  expression
       in  parenthesis	is  interpreted	 as a modifier (see the section `Modi‐
       fiers' in the section `History Expansion').  Note  that	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.  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.

zsh 4.0.1			 June 1, 2001			    ZSHEXPN(1)
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