Provided by: zsh-beta_4.3.12-dev-1+20110925-1ubuntu1_amd64 bug

NAME

       zsh-betaexpn - zsh expansion and substitution

DESCRIPTION

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

       History Expansion
              This is performed only in interactive shells.

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

       Process Substitution
       Parameter Expansion
       Command Substitution
       Arithmetic Expansion
       Brace Expansion
              These five are performed  in  one  step  in  left-to-right  fashion.   After  these
              expansions,  all  unquoted  occurrences  of  the  characters  `\',  `'' and `"' are
              removed.

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

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

       The following sections explain the types of expansion in detail.

HISTORY EXPANSION

       History  expansion allows you to use words from previous command lines in the command line
       you are typing.  This simplifies spelling corrections and the  repetition  of  complicated
       commands or arguments.  Immediately before execution, each command is saved in the history
       list, the size of which is controlled by the HISTSIZE  parameter.   The  one  most  recent
       command  is always retained in any case.  Each saved command in the history list is called
       a history event and is assigned a number, beginning with 1 (one) when the shell starts up.
       The  history  number that you may see in your prompt (see EXPANSION OF PROMPT SEQUENCES in
       zsh-betamisc(1)) is the number that is to be assigned to the next command.

   Overview
       A history expansion begins with the first character of the histchars parameter,  which  is
       `!'  by  default,  and  may  occur anywhere on the command line; history expansions do not
       nest.  The `!' can be escaped with `\' or can be enclosed between a pair of single  quotes
       ('')  to  suppress  its special meaning.  Double quotes will not work for this.  Following
       this  history  character  is  an  optional  event  designator  (see  the  section   `Event
       Designators')  and  then  an optional word designator (the section `Word Designators'); if
       neither of these designators is present, no history expansion occurs.

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

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

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

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

       If the shell encounters the character sequence `!"' in the input, the history mechanism is
       temporarily  disabled  until  the current list (see zsh-betamisc(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 support is provided by
       the fc builtin.

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

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

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

       !n     Refer to command-line n.

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

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

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

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

       !{...} Insulate a history reference from adjacent characters (if necessary).

   Word Designators
       A word designator indicates which word or words of a given command line are to be included
       in a history 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 modifiers also work on the result of filename
       generation and parameter expansion, except where noted.

       a      Turn a file name into  an  absolute  path:   prepends  the  current  directory,  if
              necessary,  and  resolves  any  use  of  `..'  and  `.' in the path.  Note that the
              transformation takes place even if the file or any intervening directories  do  not
              exist.

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

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

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

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

       l      Convert the words to all lowercase.

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

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

       Q      Remove one level of quotes from the substituted words.

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

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

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

              See further notes on this form of substitution below.

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

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

       u      Convert the words to all uppercase.

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

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

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

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

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

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

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

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

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

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

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

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

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

PROCESS SUBSTITUTION

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

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

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

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

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

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

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

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

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

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

       There  is  an  additional  problem  with  >(process); when this is attached to an external
       command, the parent shell does not wait for process to finish  and  hence  an  immediately
       following command cannot rely on the results being complete.  The problem and solution are
       the same as described in the section MULTIOS in zsh-betamisc(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 subsitution.  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.

PARAMETER EXPANSION

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

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

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

       ${name}
              The  value,  if any, of the parameter name is substituted.  The braces are required
              if the expansion is to be followed by a letter, digit, or underscore that is not to
              be   interpreted  as  part  of  name.   In  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 subscript or any colon modifiers
              appearing after the name, or any of the  characters  `^',  `=',  `~',  `#'  or  `+'
              appearing before the name, all of which work with or without braces.

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

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

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

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

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

       ${name?word}
       ${name:?word}
              In  the  first  form, if name is set, or in the second form if name is both set and
              non-null, then 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 message is printed.

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

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

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

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

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

       ${name:offset}
       ${name:offset:length}
              This   syntax   gives  effects  similar  to  parameter  subscripting  in  the  form
              $name[start,end], but is 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  substitute  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 offset, 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  substution would otherwise return a scalar, or the array starting at
              the fourth element if $foo would return  an  array.   Note  that  with  the  option
              KSH_ARRAYS  $foo  always  returns  a  scalar  (regardless  of the use of the offset
              syntax) and a form such as $foo[*]:3 is required to extract elements  of  an  array
              named foo.

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

              For further compatibility with other shells there  is  a  special  case  for  array
              offset  0.   This  usually accesses to the first element of the array.  However, if
              the substitution refers the positional 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} substitutes $1.

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

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

              The  first  `/' may be preceded by a `:', in which case the match will only succeed
              if it matches the entire word.  Note also the effect  of  the  I  and  S  parameter
              expansion flags below; however, the flags M, R, B, E and N are not useful.

              For example,

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

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

       ${#spec}
              If spec is one of the above substitutions, substitute the length in  characters  of
              the  result  instead  of  the  result  itself.   If  spec  is  an array expression,
              substitute the number of elements of the result.  Note  that  `^',  `=',  and  `~',
              below, must appear to the left of `#' when these forms are combined.

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

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

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

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

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

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

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

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

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

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

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

       %      Expand all % escapes in the resulting words in the same  way  as  in  prompts  (see
              EXPANSION  OF  PROMPT  SEQUENCES  in zsh-betamisc(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      Create an array parameter with `${...=...}', `${...:=...}' or  `${...::=...}'.   If
              this  flag  is  repeated  (as  in  `AA'),  create  an  associative array parameter.
              Assignment is made before sorting or padding.  The name part may be  a  subscripted
              range for ordinary arrays; the word part must be converted to an array, for example
              by  using  `${(AA)=name=...}'  to  activate  field  splitting,  when  creating   an
              associative array.

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

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

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

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

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

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

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

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

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

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

       L      Convert all letters in the result to lower case.

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

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

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

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

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

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

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

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

       Q      Remove one level of quotes from the resulting words.

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

              local  for local parameters

              left   for left justified parameters

              right_blanks
                     for right justified parameters with leading blanks

              right_zeros
                     for right justified parameters with leading zeros

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

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

              readonly
                     for readonly parameters

              tag    for tagged parameters

              export for exported parameters

              unique for arrays which keep only the first occurrence of duplicated values

              hide   for parameters with the `hide' flag

              special
                     for special parameters defined by the shell

       u      Expand only the first occurrence of each unique word.

       U      Convert all letters in the result to upper case.

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

       V      Make any special characters in the resulting words visible.

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

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

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

       z      Split the result of the expansion into words using shell parsing to find the words,
              i.e.  taking  into  account  any  quoting  in  the value.  Comments are not treated
              specially  but  as  ordinary  strings,  similar  to  interactive  shells  with  the
              INTERACTIVE_COMMENTS option unset.

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

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

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

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

       ~      Force string arguments to any of the flags below that follow within the parentheses
              to be treated as patterns.  Compare with a ~ outside parentheses, which forces  the
              entire substituted string to be treated as a pattern.  Hence, for example,
              [[ "?" = ${(~j.|.)array} ]]
       with  the  EXTENDED_GLOB option set succeeds if and only if $array contains the string `?'
       as an element.  The argument may be repeated to toggle  the  behaviour;  its  effect  only
       lasts to the end of the parenthesised group.

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

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

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

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

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

              Control  characters  are  always  assumed  to  be  one  unit  wide; this allows the
              mechanism to be used for 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 certain
              Asian character sets and certain special effects use  wider  characters;  combining
              characters  have  zero  width.  Non-printable characters are arbitrarily counted as
              zero width; how they would actually be displayed will vary.

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

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

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

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

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

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

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

       Z:opts:
              As z but takes a  combination  of  option  letters  between  a  following  pair  of
              delimiter  characters.   (Z+c+)  causes  comments  to  be  parsed  as  a string and
              retained; any field in the resulting  array  beginning  with  an  unquoted  comment
              character is a comment.  (Z+C+) causes comments to be parsed and removed.  The rule
              for comments is standard: anything between a word starting with the third character
              of  $HISTCHARS,  default  #,  up  to  the next newline is a comment.  (Z+n+) causes
              unquoted newlines to be treated as ordinary whitespace, else they are treated as if
              they are shell code delimiters and converted to semicolons.

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

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

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

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

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

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

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

       E      Include the index of the end of the match in the result.

       M      Include the matched portion in the result.

       N      Include the length of the match in the result.

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

   Rules
       Here  is  a  summary  of  the rules for substitution; this assumes that braces are present
       around the substitution, i.e. ${...}.  Some particular examples  are  given  below.   Note
       that  the  Zsh  Development Group accepts no 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 substitution takes account of whether the
              current value is a scalar or an array, whether the whole substitution is in  double
              quotes,  and  what flags are supplied to the current level of substitution, just as
              if the nested substitution were the outermost.  The flags are not propagated up  to
              enclosing  substitutions; the nested substitution will return either a scalar or an
              array as determined by the flags, possibly adjusted for quoting.  All the following
              steps take place where applicable at all levels of substitution.  Note that, unless
              the `(P)' flag is present, the flags and any subscripts apply directly to the value
              of  the  nested  substitution; for example, the expansion ${${foo}} behaves exactly
              the same as ${foo}.

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

       2. Internal Parameter Flags
              Any parameter flags set by one of the typeset family of commands, in particular the
              L, R, Z, u and l flags for padding and capitalization, are applied directly to  the
              parameter value.

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

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

       5. Double-Quoted Joining
              If the value after this process is an array, and the substitution appears in double
              quotes, and no (@) flag is present at the current level, the words of the value are
              joined with the first character of the parameter $IFS, by default a space,  between
              each  word (single word arrays are not modified).  If the (j) flag is present, that
              is used for joining instead of $IFS.

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

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

       8. Character evaluation
              Any (#) flag is applied, evaluating the result so far numerically as a character.

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

       10. Forced Joining
              If the `(j)' flag is present, or no `(j)' flag is present but the string is  to  be
              split  as given by rules 16. or 17., and joining did not take place at step 5., any
              words in the value are  joined  together  using  the  given  string  or  the  first
              character  of  $IFS if none.  Note that the `(F)' flag implicitly supplies a string
              for joining in this manner.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       ${(s/x/)foo%%1*}
              produces `a' and ` b' (note the extra space).  As substitution occurs before either
              joining or 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 `$(...)', or quoted with
       grave  accents,  like  ``...`',  is  replaced  with its standard output, with any trailing
       newlines deleted.  If the substitution is not enclosed in double  quotes,  the  output  is
       broken  into words using the IFS parameter.  The substitution `$(cat foo)' may be replaced
       by the equivalent but faster `$(<foo)'.  In either case, if the option GLOB_SUBST is  set,
       the output is eligible for filename generation.

ARITHMETIC EXPANSION

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

BRACE EXPANSION

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

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

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

       If  a  brace  expression matches none of the above forms, it is left unchanged, unless the
       option BRACE_CCL (an abbreviation for `brace character class') is set.  In that  case,  it
       is  expanded  to  a  list  of the individual characters between the braces sorted into the
       order of the characters in the ASCII character set (multibyte characters are not currently
       handled).   The  syntax  is  similar  to a [...] expression in filename generation: `-' is
       treated specially to denote a range of characters, but `^' or `!' as the  first  character
       is treated 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  (globbing);  an  expression
       such  as  */{foo,bar}  is  split  into  two separate words */foo and */bar before filename
       generation takes place.  In particular, note that this is liable to produce a  `no  match'
       error  if  either  of  the  two  expressions does not match; this is to be contrasted with
       */(foo|bar), which is treated as a single pattern but otherwise has similar effects.

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

FILENAME EXPANSION

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

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

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

   Dynamic named directories
       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 naming.  The functions are tried in
       order until one returns status zero, so it is important that functions test  whether  they
       can handle the case in question and return an appropriate status.

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

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

              reply=(s 16)

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

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

       The completion system  calls  `zsh_directory_name  c'  followed  by  equivalent  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 zsh-betacompsys(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.

       In  certain  circumstances  (in  prompts, for instance), when the shell prints a path, the
       path is checked to see if it has a named directory as its prefix.  If so, then the  prefix
       portion is replaced with a `~' followed by the name of the directory.  The shortest way of
       referring to the directory is used, with ties broken in favour of using a named directory,
       except  when  the  directory  is  /  itself.   The  parameters  $PWD and $OLDPWD are never
       abbreviated in this fashion.

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

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

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

FILENAME GENERATION

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

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

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

              [:cntrl:]
                     The character is a control character

              [:digit:]
                     The character is a decimal digit

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

              [:lower:]
                     The character is a lowercase letter

              [:print:]
                     The character is printable

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

              [:space:]
                     The character is whitespace

              [:upper:]
                     The character is an uppercase letter

              [:xdigit:]
                     The character is a hexadecimal digit

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

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

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

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

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

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

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

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

              Be careful when using other wildcards  adjacent  to  patterns  of  this  form;  for
              example,  <0-9>*  will  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 consequence of
              the rule that the longest possible match  always  succeeds.   Expressions  such  as
              `<0-9>[^[:digit:]]*' can be used instead.

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

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

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

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

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

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

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

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

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

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

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

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

   Globbing Flags
       There are various flags which affect any text  to  their  right  up  to  the  end  of  the
       enclosing  group  or to the end of the pattern; they require the EXTENDED_GLOB option. All
       take the form (#X) where X may have one of the 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  element  of  each  array
              corresponding  to  the  first parenthesised group, and so on.  These arrays are not
              otherwise special to the shell.  The  indices  use  the  same  convention  as  does
              parameter  substitution,  so  that  elements  of  $mend  and $mbegin may be used in
              subscripts; the KSH_ARRAYS option is respected.  Sets of  globbing  flags  are  not
              considered  parenthesised  groups;  only  the  first nine active parentheses can be
              referenced.

              For example,

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

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

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

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

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

              Pattern matching with backreferences is slightly slower than without.

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

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

       m      Set  references to the match data for the entire string matched; this is similar to
              backreferencing and does not work in filename generation.   The  flag  must  be  in
              effect at the end of the pattern, i.e. not local to a group. The parameters $MATCH,
              $MBEGIN and $MEND will be set to the string matched  and  to  the  indices  of  the
              beginning  and  end  of the string, respectively.  This is most useful in parameter
              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,  printing  `vEldt  jynx
              grImps wAqf zhO bUck'.

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

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

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

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

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

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

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

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

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

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

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

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

       1.     Different characters, as in fooxbar and fooybar.

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

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

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

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

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

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

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

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

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

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

              ls (*/)#bar

       or

              ls **/bar

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

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

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

       If  the  option EXTENDED_GLOB is set, a different syntax for glob qualifiers is available,
       namely `(#qx)' where x is any of the same glob qualifiers used in the other  format.   The
       qualifiers  must  still  appear  at  the  end  of  the pattern.  However, with this syntax
       multiple glob qualifiers may be chained together.  They are treated as a  logical  AND  of
       the  individual sets of flags.  Also, as the syntax is unambiguous, the expression will be
       treated as glob qualifiers just as long any parentheses contained within it are  balanced;
       appearance  of  `|',  `(' or `~' does not negate the effect.  Note that qualifiers will be
       recognised in this form even if a bare glob qualifier exists at the end  of  the  pattern,
       for  example  `*(#q*)(.)' will recognise executable regular files if both options are set;
       however, mixed syntax should probably be avoided for the sake of clarity.

       A qualifier may be any one of the following:

       /      directories

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

       .      plain files

       @      symbolic links

       =      sockets

       p      named pipes (FIFOs)

       *      executable plain files (0100)

       %      device files (character or block special)

       %b     block special files

       %c     character special files

       r      owner-readable files (0400)

       w      owner-writable files (0200)

       x      owner-executable files (0100)

       A      group-readable files (0040)

       I      group-writable files (0020)

       E      group-executable files (0010)

       R      world-readable files (0004)

       W      world-writable files (0002)

       X      world-executable files (0001)

       s      setuid files (04000)

       S      setgid files (02000)

       t      files with the sticky bit (01000)

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

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

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

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

              In  the  first  form, the first character after the `e' will be used as a separator
              and anything up to the next matching separator will be taken  as the  string;  `[',
              `{',  and  `<'  match  `]',  `}',  and `>', 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 execution.

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

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

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

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

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

       ddev   files on the device dev

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

       U      files owned by the effective user ID

       G      files owned by the effective group ID

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

       gid    like uid but with group IDs or names

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

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

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

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

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

              If  this  flag  is  directly followed by a `k' (`K'), `m' (`M'), or `p' (`P') (e.g.
              `Lk-50') the check is performed with kilobytes, megabytes, or blocks (of 512 bytes)
              instead.   In  this  case a file is regarded as "exactly" the size if the file size
              rounded up to the next unit is equal to the  test  size.   Hence  `*(Lm1)'  matches
              files  from  1  byte  up  to 1 Megabyte inclusive.  Note also that the set of files
              "less than" the test size only includes files that would  not  match  the  equality
              test; hence `*(Lm-1)' only matches files of zero size.

       ^      negates all qualifiers following it

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

       M      sets the MARK_DIRS option for the current pattern

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

       N      sets the NULL_GLOB option for the current pattern

       D      sets the GLOB_DOTS option for the current pattern

       n      sets the NUMERIC_GLOB_SORT option for the current pattern

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

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

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

       [beg[,end]]
              specifies  which  of the matched filenames should be included in the returned list.
              The syntax is the same as for array subscripts. beg and the  optional  end  may  be
              mathematical expressions. As in parameter 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 occurrences of a file
              name; for example, the pattern `*(P:-f:)' produces the command line  arguments  `-f
              file1 -f file2 ...'

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

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

              ls *(-/)

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

              ls *(%W)

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

              ls *(W,X)

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

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

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

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

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

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

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