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ZSHEXPN(1)		    General Commands Manual		    ZSHEXPN(1)

NAME
       zshexpn - zsh expansion and substitution

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

       History Expansion
	      This is performed	only in	interactive shells.

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

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

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

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

       The following sections explain the types	of expansion in	detail.

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

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

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

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

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

       History expansions do not nest.

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

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

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

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

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

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

       !      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  re-
	      peats 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 be-
	      fore 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  ex-
       pansion,	except where noted.

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

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

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

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

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

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

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

       h [ digits ]
	      Remove a trailing	pathname component, shortening the path	by one
	      directory	level: this is the `head' of the pathname.  This works
	      like  `dirname'.	If the h is followed immediately (with no spa-
	      ces or other separator) by any number of decimal digits, and the
	      value  of	the resulting number is	non-zero, that number of lead-
	      ing components is	preserved instead of the final component being
	      removed.	 In an absolute	path the leading `/' is	the first com-
	      ponent, so,  for	example,  if  var=/my/path/to/something,  then
	      ${var:h3}	 substitutes  /my/path.	  Consecutive `/'s are treated
	      the same as a single `/'.	 In parameter substitution, digits may
	      only  be used if the expression is in braces, so for example the
	      short form substitution $var:h2 is treated as ${var:h}2, not  as
	      ${var:h2}.   No restriction applies to the use of	digits in his-
	      tory substitution	or globbing qualifiers.	  If  more  components
	      are  requested  than are present,	the entire path	is substituted
	      (so this does not	trigger	a `failed modifier' error  in  history
	      expansion).

       l      Convert the words	to all lowercase.

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

       P      Turn a file name into an absolute	path, like  realpath(3).   The
	      resulting	 path  will be absolute, will refer to the same	direc-
	      tory entry as the	input filename,	and  none  of  its  components
	      will be symbolic links or	equal to `.' or	`..'.

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

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

       Q      Remove one level of quotes from the substituted words.

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

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

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

	      See further notes	on this	form of	substitution below.

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

       t [ digits ]
	      Remove all leading pathname components, leaving the final	compo-
	      nent  (tail).  This works	like `basename'.  Any trailing slashes
	      are first	removed.  Decimal  digits  are	handled	 as  described
	      above  for  (h), but in this case	that number of trailing	compo-
	      nents is preserved instead of the	default	1; 0  is  treated  the
	      same as 1.

       u      Convert the words	to all uppercase.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      (mycmd =(myoutput)) &!

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

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

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

       outputs something resembling the	following

	      File /tmp/zsh6nU0kS:
	      This be the verse

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

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

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

       With default options, after the assignments:

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

       then  $array  substitutes two words, `first word' and `third word', and
       $scalar substitutes a single word `only word'.  Note that  second  ele-
       ment of array was elided.  Scalar parameters can	be elided too if their
       value is	null (empty).  To  avoid  elision,  use	 quoting  as  follows:
       "$scalar"  for  scalars	and "${array[@]}" or "${(@)array}" for arrays.
       (The last two forms are equivalent.)

       Parameter expansions can	involve	flags, as  in  `${(@kv)aliases}',  and
       other  operators,  such as `${PREFIX:-"/usr/local"}'.  Parameter	expan-
       sions can also be nested.  These	topics will be introduced below.   The
       full rules are complicated and are noted	at the end.

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

       In  the	following descriptions,	`word' refers to a single word substi-
       tuted on	the command line, not necessarily a space delimited word.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      For example,

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

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

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

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

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

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

       ${=spec}
       ${==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 af-
	      fects the	result of array	assignments with the A flag.

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

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

       If  a ${...} type parameter expression or a $(...) type command substi-
       tution is used in place of name above, it is expanded first and the re-
       sult  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  ex-
       amples  below.  Each name or nested ${...} in a parameter expansion may
       also be followed	by a subscript expression as described in Array	Param-
       eters 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 $(foo), but the flag	`(f)' (see be-
       low) is applied using the rules for unquoted expansions.	 Note  further
       that  quotes  are  themselves  nested  in this context; for example, in
       "${(@f)"$(foo)"}", there	are two	sets of	quotes,	 one  surrounding  the
       whole  expression,  the other (redundant) surrounding the $(foo)	as be-
       fore.

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

       #      Evaluate	the  resulting words as	numeric	expressions and	inter-
	      pret these as character codes.  Output the corresponding charac-
	      ters.   Note that	this form is entirely distinct from use	of the
	      #	without	parentheses.

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

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

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

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

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

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

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

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

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

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

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

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

	      is always	true for any possible value of $str.

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

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

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

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

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

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

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

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

       k      If name refers to	an associative array, substitute the keys (el-
	      ement  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.
	      With  the	KSH_ARRAYS option a subscript `[*]' or `[@]' is	needed
	      to operate on the	whole array, as	usual.

       L      Convert all letters in the result	to lower case.

       n      Sort decimal integers numerically; if the	first differing	 char-
	      acters  of  two test strings are not digits, sorting is lexical.
	      `+' and `-' are not treated specially; they are treated  as  any
	      other  non-digit.	  Integers with	more initial zeroes are	sorted
	      before those with	fewer or none.	Hence the array	 `foo+24  foo1
	      foo02  foo2  foo3	 foo20	foo23' is sorted into the order	shown.
	      May be combined with `i' or `O'.

       -      As n, but	a leading minus	sign indicates a negative decimal  in-
	      teger.  A	leading	minus sign not followed	by an integer does not
	      trigger numeric sorting.	Note that `+' signs  are  not  handled
	      specially	(this may change in the	future).

       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', `n' or `-'.

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

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

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

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

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

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

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

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

       Q      Remove one level of quotes from the resulting words.

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

	      local  for local parameters

	      left   for left justified	parameters

	      right_blanks
		     for right justified parameters with leading blanks

	      right_zeros
		     for right justified parameters with leading zeros

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

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

	      readonly
		     for readonly parameters

	      tag    for tagged	parameters

	      tied   for parameters tied to another parameter in the manner of
		     PATH  (colon-separated  list)  and	 path (array), whether
		     these are special parameters or user-defined with	`type-
		     set -T'

	      export for exported parameters

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

	      hide   for parameters with the `hide' flag

	      hideval
		     for parameters with the `hideval' flag

	      special
		     for special parameters defined by the shell

       u      Expand only the first occurrence of each unique word.

       U      Convert all letters in the result	to upper case.

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

       V      Make any special characters in the resulting words visible.

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

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

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

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

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

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

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

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

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

	      For example,

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

	      splits the variable on a :.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       Z:opts:
	      As z but takes a combination of option letters between a follow-
	      ing pair of delimiter characters.	 With no options the effect is
	      identical	to z.  The following options are available:

	      (Z+c+) causes comments to	be parsed as a	string	and  retained;
		     any  field	 in  the resulting array beginning with	an un-
		     quoted comment character is a comment.

	      (Z+C+) causes comments to	be parsed and removed.	The  rule  for
		     comments  is  standard:  anything between a word starting
		     with the third character of $HISTCHARS, default #,	up  to
		     the next newline is a comment.

	      (Z+n+) causes unquoted newlines to be treated as ordinary	white-
		     space, else they are treated as if	they  are  shell  code
		     delimiters	and converted to semicolons.

	      Options  are  combined  within  the same set of delimiters, e.g.
	      (Z+Cn+).

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

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

       S      With  #  or  ##, search for the match that starts	closest	to the
	      start of the string (a `substring	match'). Of all	matches	 at  a
	      particular position, # selects the shortest and ## the longest:

		     % str="aXbXc"
		     % echo ${(S)str#X*}
		     abXc
		     % echo ${(S)str##X*}
		     a
		     %

	      With  %  or  %%, search for the match that starts	closest	to the
	      end of the string:

		     % str="aXbXc"
		     % echo ${(S)str%X*}
		     aXbc
		     % echo ${(S)str%%X*}
		     aXb
		     %

	      (Note that % and %% don't	search for the match that ends closest
	      to the end of the	string,	as one might expect.)

	      With  substitution  via  ${.../...}  or  ${...//...},  specifies
	      non-greedy matching, i.e.	that the shortest instead of the long-
	      est match	should be replaced:

		     % str="abab"
		     % echo ${str/*b/_}
		     _
		     % echo ${(S)str/*b/_}
		     _ab
		     %

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

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

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

       *      Enable  EXTENDED_GLOB  for  substitution	 via   ${.../...}   or
	      ${...//...}.  Note that `**' does	not disable extendedglob.

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

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

       M      Include the matched portion in the result.

       N      Include the length of the	match in the result.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

COMMAND	SUBSTITUTION
       A command enclosed in parentheses  preceded  by	a  dollar  sign,  like
       `$(...)',  or quoted with grave accents,	like ``...`', is replaced with
       its standard output, with any trailing newlines deleted.	 If  the  sub-
       stitution  is  not enclosed in double quotes, the output	is broken into
       words using the IFS parameter.

       The substitution	`$(cat foo)' may be replaced by	the faster  `$(<foo)'.
       In  this	case foo undergoes single word shell expansions	(parameter ex-
       pansion,	command	substitution and arithmetic expansion),	but not	 file-
       name generation.

       If  the	option	GLOB_SUBST  is set, the	result of any unquoted command
       substitution, including the special form	just  mentioned,  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  or-
       der to include them literally in	a word.

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

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

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

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

       Note that brace expansion is not	part  of  filename  generation	(glob-
       bing);  an  expression  such  as	*/{foo,bar} is split into two separate
       words */foo and */bar before filename generation	takes place.  In  par-
       ticular,	 note that this	is liable to produce a `no match' error	if ei-
       ther 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 de-
       scribed 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,  re-
       spectively.

       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 di-
       rectory 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 ex-
       changes the effects of `~+' and `~-' where they are followed by a  num-
       ber.

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

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

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

	      reply=(s 16)

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

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

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

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

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

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

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

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

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

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

       If  the option MAGIC_EQUAL_SUBST	is set,	any unquoted shell argument in
       the form	`identifier=expression'	becomes	eligible for file expansion as
       described  in  the  previous paragraph.	Quoting	the first `=' also in-
       hibits 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  op-
       tion  is	 set, the `^' and `#' characters also denote a pattern;	other-
       wise they are not treated specially by the shell.

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

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

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

       ?      Matches any character.

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

	      [:alnum:]
		     The character is alphanumeric

	      [:alpha:]
		     The character is alphabetic

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

	      [:blank:]
		     The character is a	blank character

	      [:cntrl:]
		     The character is a	control	character

	      [:digit:]
		     The character is a	decimal	digit

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

	      [:lower:]
		     The character is a	lowercase letter

	      [:print:]
		     The character is printable

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

	      [:space:]
		     The character is whitespace

	      [:upper:]
		     The character is an uppercase letter

	      [:xdigit:]
		     The character is a	hexadecimal digit

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

	      [:IDENT:]
		     The  character is allowed to form part of a shell identi-
		     fier, such	as a parameter name; this  test	 respects  the
		     POSIX_IDENTIFIERS option

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      For example,

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

	      prints `string_with_a_message'.  Note  that  the	first  set  of
	      parentheses  is before the (#b) and does not create a backrefer-
	      ence.

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

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

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

	      Pattern  matching	 with  backreferences  is slightly slower than
	      without.

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

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

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

	      For example,

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

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

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

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

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

       s, e   Unlike the other flags, these have only a	local effect, and each
	      must appear on its own:  `(#s)' and `(#e)' are  the  only	 valid
	      forms.   The  `(#s)' flag	succeeds only at the start of the test
	      string, and the `(#e)' flag succeeds only	at the end of the test
	      string;  they  correspond	to `^' and `$' in standard regular ex-
	      pressions.  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	`${ar-
	      ray/(#s)A*Z(#e)}'	will remove only elements of  an  array	 which
	      match  the complete pattern `A*Z'.  There	are other ways of per-
	      forming many operations of this type, however the	combination of
	      the  substitution	 operations  `/'  and `//' with	the `(#s)' and
	      `(#e)' flags provides a single simple and	memorable method.

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

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

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

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

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

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

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

       1.     Different	characters, as in fooxbar and fooybar.

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

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

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

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

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

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

       Apart from exclusions, there is only one	overall	error count;  however,
       the  maximum errors allowed may be altered locally, and this can	be de-
       limited by grouping.  For example, (#a1)cat((#a0)dog)fox	allows one er-
       ror  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 ap-
       proximate 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	there-
       fore  matches files in the current directory as well as subdirectories.
       Thus:

	      ls -ld --	(*/)#bar

       or

	      ls -ld --	**/bar

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

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

	      setopt GLOBSTARSHORT
	      ls -ld --	**.c

       is equivalent to

	      ls -ld --	**/*.c

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

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

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

       A qualifier may be any one of the following:

       /      directories

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

       .      plain files

       @      symbolic links

       =      sockets

       p      named pipes (FIFOs)

       *      executable plain files (0100 or 0010 or 0001)

       %      device files (character or block special)

       %b     block special files

       %c     character	special	files

       r      owner-readable files (0400)

       w      owner-writable files (0200)

       x      owner-executable files (0100)

       A      group-readable files (0040)

       I      group-writable files (0020)

       E      group-executable files (0010)

       R      world-readable files (0004)

       W      world-writable files (0002)

       X      world-executable files (0001)

       s      setuid files (04000)

       S      setgid files (02000)

       t      files with the sticky bit	(01000)

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

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

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

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

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

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

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

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

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

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

       ddev   files on the device dev

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

       U      files owned by the effective user	ID

       G      files owned by the effective group ID

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

       gid    like uid but with	group IDs or names

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

	      Any  fractional  part  of	the difference between the access time
	      and the current part in the appropriate units is ignored in  the
	      comparison.   For	 instance, `echo *(ah-5)' would	echo files ac-
	      cessed 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 in-
	      ode change time.

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

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

       ^      negates all qualifiers following it

       -      toggles  between	making	the  qualifiers	work on	symbolic links
	      (the default) and	the files they point to, if any; any  symbolic
	      link for whose target the	`stat' system call fails (whatever the
	      cause of the failure) is treated as a file in its	own right

       M      sets the MARK_DIRS option	for the	current	pattern

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

       N      sets the NULL_GLOB option	for the	current	pattern

       D      sets the GLOB_DOTS option	for the	current	pattern

       n      sets the NUMERIC_GLOB_SORT option	for the	current	pattern

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

	      Implies oN when no oc qualifier is used.

       oc     specifies	 how the names of the files should be sorted. The fol-
	      lowing values of c sort in the following ways:

	      n	     By	name.
	      L	     By	the size (length) of the files.
	      l	     By	number of links.
	      a	     By	time of	last access, youngest first.
	      m	     By	time of	last modification, youngest first.
	      c	     By	time of	last inode change, youngest first.
	      d	     By	directories: 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.
	      N	     No	sorting	is performed.
	      estring
	      +cmd   Sort by shell code	(see below).

	      Note that	the modifiers ^	and - are used,	so `*(^-oL)'  gives  a
	      list  of all files sorted	by file	size in	descending order, fol-
	      lowing any symbolic links.  Unless oN is	used,  multiple	 order
	      specifiers may occur to resolve ties.

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

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

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

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

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

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

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

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

       If a `:'	appears	in a qualifier list, the remainder of  the  expression
       in  parenthesis	is  interpreted	 as a modifier (see the	section	`Modi-
       fiers' in the section `History Expansion').  Each modifier must be  in-
       troduced	 by a separate `:'.  Note also that the	result after modifica-
       tion 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 ac-
       tual 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 -ld --	*(-/)

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

	      ls -ld --	*(-@)

       lists all broken	symbolic links,	and

	      ls -ld --	*(%W)

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

	      ls -ld --	*(W,X)

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

	      print -rC1 /tmp/foo*(u0^@:t)

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

	      ls -ld --	*.*~(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 -rC1 b*.pro(#q:s/pro/shmo/)(#q.:s/builtin/shmiltin/)

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

zsh 5.9				 May 14, 2022			    ZSHEXPN(1)

NAME | DESCRIPTION | HISTORY EXPANSION | PROCESS SUBSTITUTION | PARAMETER EXPANSION | COMMAND SUBSTITUTION | ARITHMETIC EXPANSION | BRACE EXPANSION | FILENAME EXPANSION | FILENAME GENERATION

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=zshexpn&sektion=1&manpath=FreeBSD+13.1-RELEASE+and+Ports>

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