zshmisc



ZSHMISC(1)                                                          ZSHMISC(1)




NAME

       zshmisc - everything and then some


SIMPLE COMMANDS & PIPELINES

       A  simple  command is a sequence of optional parameter assignments fol-
       lowed by  blank-separated  words,  with  optional  redirections  inter-
       spersed.  The first word is the command to be executed, and the remain-
       ing words, if any, are arguments to the command.  If a command name  is
       given,  the parameter assignments modify the environment of the command
       when it is executed.  The value of a simple command is its exit status,
       or 128 plus the signal number if terminated by a signal.  For example,

              echo foo

       is a simple command with arguments.

       A  pipeline  is  either  a simple command, or a sequence of two or more
       simple commands where each command is separated from the next by ‘|’ or
       ‘|&’.   Where commands are separated by ‘|’, the standard output of the
       first command is connected to the standard input of the next.  ‘|&’  is
       shorthand for ‘2>&1 |’, which connects both the standard output and the
       standard error of the command to the standard input of the  next.   The
       value  of  a  pipeline  is  the  value  of the last command, unless the
       pipeline is preceded by ‘!’ in which case  the  value  is  the  logical
       inverse of the value of the last command.  For example,

              echo foo | sed s/foo/bar/

       is  a  pipeline,  where  the output (‘foo’ plus a newline) of the first
       command will be passed to the input of the second.

       If a pipeline is preceded by ‘coproc’, it is executed as a coprocess; a
       two-way pipe is established between it and the parent shell.  The shell
       can read from or write to the coprocess by means of the ‘>&p’ and ‘<&p’
       redirection  operators  or  with  ‘print -p’ and ‘read -p’.  A pipeline
       cannot be preceded by both ‘coproc’ and ‘!’.  If job control is active,
       the coprocess can be treated in other than input and output as an ordi-
       nary background job.

       A sublist is either a single pipeline, or a sequence  of  two  or  more
       pipelines separated by ‘&&’ or ‘||’.  If two pipelines are separated by
       ‘&&’, the second pipeline  is  executed  only  if  the  first  succeeds
       (returns  a  zero  value).  If two pipelines are separated by ‘||’, the
       second is executed only if the first fails (returns a  nonzero  value).
       Both  operators  have  equal  precedence and are left associative.  The
       value of the sublist is the value of the last pipeline  executed.   For
       example,

              dmesg | grep panic && print yes

       is a sublist consisting of two pipelines, the second just a simple com-
       mand which will be executed if and only if the grep command  returns  a
       zero  value.   If  it does not, the value of the sublist is that return
       value, else it is the value returned by  the  print  (almost  certainly
       zero).

       A list is a sequence of zero or more sublists, in which each sublist is
       terminated by ‘;’, ‘&’, ‘&|’, ‘&!’, or a newline.  This terminator  may
       optionally  be  omitted from the last sublist in the list when the list
       appears as a complex command inside ‘(...)’  or ‘{...}’.  When  a  sub-
       list  is terminated by ‘;’ or newline, the shell waits for it to finish
       before executing the next sublist.  If a sublist  is  terminated  by  a
       ‘&’,  ‘&|’,  or ‘&!’, the shell executes the last pipeline in it in the
       background, and does not wait for it to  finish  (note  the  difference
       from  other  shells which execute the whole sublist in the background).
       A backgrounded pipeline returns a status of zero.

       More generally, a list can be seen as a set of any shell commands what-
       soever,  including the complex commands below; this is implied wherever
       the word ‘list’ appears in later descriptions.  For example,  the  com-
       mands in a shell function form a special sort of list.


PRECOMMAND MODIFIERS

       A  simple  command may be preceded by a precommand modifier, which will
       alter how the  command  is  interpreted.   These  modifiers  are  shell
       builtin  commands  with  the exception of nocorrect which is a reserved
       word.

       -      The command is executed with a  ‘-’  prepended  to  its  argv[0]
              string.

       noglob Filename  generation  (globbing)  is not performed on any of the
              words.

       nocorrect
              Spelling correction is not done on any of the words.  This  must
              appear  before  any  other  precommand modifier, as it is inter-
              preted immediately, before any  parsing  is  done.   It  has  no
              effect in non-interactive shells.

       exec   The command is executed in the parent shell without forking.

       command
              The command word is taken to be the name of an external command,
              rather than a shell function or builtin.

       builtin
              The command word is taken to be the name of a  builtin  command,
              rather than a shell function or external command.


COMPLEX COMMANDS

       A complex command in zsh is one of the following:

       if list then list [ elif list then list ] ... [ else list ] fi
              The  if  list is executed, and if it returns a zero exit status,
              the then list is executed.  Otherwise, the elif list is executed
              and  if  its  value is zero, the then list is executed.  If each
              elif list returns nonzero, the else list is executed.

       for name ... [ in word ... ] term do list done
              where term is at least one newline or ;.   Expand  the  list  of
              words,  and set the parameter name to each of them in turn, exe-
              cuting list each time.  If the in word is omitted, use the posi-
              tional parameters instead of the words.

              More  than  one  parameter  name  can  appear before the list of
              words.  If N names are given, then on each execution of the loop
              the  next  N words are assigned to the corresponding parameters.
              If there are more names  than  remaining  words,  the  remaining
              parameters  are  each set to the empty string.  Execution of the
              loop ends when there is no remaining word to assign to the first
              name.  It is only possible for in to appear as the first name in
              the list, else it will be treated as  marking  the  end  of  the
              list.

       for (( [expr1] ; [expr2] ; [expr3] )) do list done
              The arithmetic expression expr1 is evaluated first (see the sec-
              tion ‘Arithmetic Evaluation’).  The arithmetic expression  expr2
              is  repeatedly  evaluated  until  it  evaluates to zero and when
              non-zero, list is executed and the arithmetic  expression  expr3
              evaluated.   If any expression is omitted, then it behaves as if
              it evaluated to 1.

       while list do list done
              Execute the do list as long as the while  list  returns  a  zero
              exit status.

       until list do list done
              Execute the do list as long as until list returns a nonzero exit
              status.

       repeat word do list done
              word is expanded and treated as an arithmetic expression,  which
              must evaluate to a number n.  list is then executed n times.

       case word in [ [(] pattern [ | pattern ] ... ) list (;;|;&) ] ... esac
              Execute  the list associated with the first pattern that matches
              word, if any.  The form of the patterns is the same as that used
              for filename generation.  See the section ‘Filename Generation’.
              If the list that is executed is terminated with ;&  rather  than
              ;;,  the  following list is also executed.  This continues until
              either a list is terminated with ;; or the esac is reached.

       select name [ in word ... term ] do list done
              where term is one or more newline or ; to terminate  the  words.
              Print  the  set  of words, each preceded by a number.  If the in
              word is omitted, use the  positional  parameters.   The  PROMPT3
              prompt is printed and a line is read from the line editor if the
              shell is interactive and that is active, or else standard input.
              If  this line consists of the number of one of the listed words,
              then the parameter name is set to the word corresponding to this
              number.   If  this  line is empty, the selection list is printed
              again.  Otherwise, the value of the parameter  name  is  set  to
              null.   The  contents  of  the  line read from standard input is
              saved in the parameter REPLY.  list is executed for each  selec-
              tion until a break or end-of-file is encountered.

       ( list )
              Execute  list  in a subshell.  Traps set by the trap builtin are
              reset to their default values while executing list.

       { list }
              Execute list.

       { try-list } always { always-list }
              First execute try-list.  Regardless of errors,  or  break,  con-
              tinue,  or  return commands encountered within try-list, execute
              always-list.  Execution then continues from the  result  of  the
              execution of try-list; in other words, any error, or break, con-
              tinue, or return command is treated in the  normal  way,  as  if
              always-list  were  not  present.   The  two  chunks  of code are
              referred to as the ‘try block’ and the ‘always block’.

              Optional newlines or semicolons may  appear  after  the  always;
              note,  however,  that they may not appear between the preceeding
              closing brace and the always.

              An ‘error’ in this context is a condition such as a syntax error
              which  causes  the shell to abort execution of the current func-
              tion, script, or list.   Syntax  errors  encountered  while  the
              shell  is  parsing  the  code do not cause the always-list to be
              executed.  For example, an erroneously constructed if  block  in
              try-list  would cause the shell to abort during parsing, so that
              always-list  would  not  be   executed,   while   an   erroneous
              substitution  such  as  ${*foo*}  would  cause a run-time error,
              after which always-list would be executed.

              An error condition can be tested  and  reset  with  the  special
              integer  variable  TRY_BLOCK_ERROR.   Outside an always-list the
              value is irrelevant,  but  it  is  initialised  to  -1.   Inside
              always-list,  the  value  is  1  if  an  error  occurred  in the
              try-list, else 0.  If TRY_BLOCK_ERROR is set  to  0  during  the
              always-list,  the  error  condition  caused  by  the try-list is
              reset, and shell execution continues normally after the  end  of
              always-list.  Altering the value during the try-list is not use-
              ful (unless this forms part of an enclosing always block).

              Regardless of TRY_BLOCK_ERROR, after the end of always-list  the
              normal  shell  status $? is the value returned from always-list.
              This  will  be  non-zero  if  there  was  an  error,   even   if
              TRY_BLOCK_ERROR was set to zero.

              The  following  executes  the given code, ignoring any errors it
              causes.  This is an alternative to the usual convention of  pro-
              tecting code by executing it in a subshell.

                     {
                         # code which may cause an error
                       } always {
                         # This code is executed regardless of the error.
                         (( TRY_BLOCK_ERROR = 0 ))
                     }
                     # The error condition has been reset.

              An  exit command encountered in try-list does not cause the exe-
              cution of always-list.  Instead,  the  shell  exits  immediately
              after any EXIT trap has been executed.

       function word ... [ () ] [ term ] { list }
       word ... () [ term ] { list }
       word ... () [ term ] command
              where term is one or more newline or ;.  Define a function which
              is referenced by any one of word.  Normally, only  one  word  is
              provided;  multiple  words  are  usually only useful for setting
              traps.  The body of the function is the list between the  {  and
              }.  See the section ‘Functions’.

              If  the  option  SH_GLOB  is  set  for  compatibility with other
              shells, then whitespace may appear between between the left  and
              right  parentheses  when there is a single word;  otherwise, the
              parentheses will be treated as forming  a  globbing  pattern  in
              that case.

       time [ pipeline ]
              The  pipeline is executed, and timing statistics are reported on
              the standard error in the form specified by the TIMEFMT  parame-
              ter.   If  pipeline is omitted, print statistics about the shell
              process and its children.

       [[ exp ]]
              Evaluates the conditional expression exp and return a zero  exit
              status if it is true.  See the section ‘Conditional Expressions’
              for a description of exp.


ALTERNATE FORMS FOR COMPLEX COMMANDS

       Many of zsh’s complex commands have alternate forms.  These  particular
       versions of complex commands should be considered deprecated and may be
       removed in the future.  The versions in the previous section should  be
       preferred instead.

       The short versions below only work if sublist is of the form ‘{ list }’
       or if the SHORT_LOOPS option is set.  For the if, while and until  com-
       mands, in both these cases the test part of the loop must also be suit-
       ably delimited, such as by ‘[[ ... ]]’ or ‘(( ... ))’, else the end  of
       the  test will not be recognized.  For the for, repeat, case and select
       commands no such special form for the arguments is necessary,  but  the
       other  condition (the special form of sublist or use of the SHORT_LOOPS
       option) still applies.

       if list { list } [ elif list { list } ] ... [ else { list } ]
              An alternate form of if.  The rules mean that

                     if [[ -o ignorebraces ]] {
                       print yes
                     }

              works, but

                     if true {  # Does not work!
                       print yes
                     }

              does not, since the test is not suitably delimited.

       if list sublist
              A short form of the alternate ‘if’.  The same limitations on the
              form of list apply as for the previous form.

       for name ... ( word ... ) sublist
              A short form of for.

       for name ... [ in word ... ] term sublist
              where  term is at least one newline or ;.  Another short form of
              for.

       for (( [expr1] ; [expr2] ; [expr3] )) sublist
              A short form of the arithmetic for command.

       foreach name ... ( word ... ) list end
              Another form of for.

       while list { list }
              An alternative form of while.  Note the limitations on the  form
              of list mentioned above.

       until list { list }
              An  alternative form of until.  Note the limitations on the form
              of list mentioned above.

       repeat word sublist
              This is a short form of repeat.

       case word { [ [(] pattern [ | pattern ] ... ) list (;;|;&) ] ... }
              An alternative form of case.

       select name [ in word term ] sublist
              where term is at least one  newline  or  ;.   A  short  form  of
              select.


RESERVED WORDS

       The  following  words are recognized as reserved words when used as the
       first word of a command unless quoted or disabled using disable -r:

       do done esac then elif else fi for case if while function  repeat  time
       until select coproc nocorrect foreach end ! [[ { }

       Additionally,  ‘}’  is  recognized in any position if the IGNORE_BRACES
       option is not set.


COMMENTS

       In noninteractive shells, or in interactive shells  with  the  INTERAC-
       TIVE_COMMENTS  option set, a word beginning with the third character of
       the histchars parameter (‘#’ by default) causes that word and  all  the
       following characters up to a newline to be ignored.


ALIASING

       Every  token  in the shell input is checked to see if there is an alias
       defined for it.  If so, it is replaced by the text of the alias  if  it
       is  in command position (if it could be the first word of a simple com-
       mand), or if the alias is global.  If the text ends with a  space,  the
       next  word  in  the shell input is treated as though it were in command
       position for purposes of alias expansion.  An alias  is  defined  using
       the alias builtin; global aliases may be defined using the -g option to
       that builtin.

       Alias expansion is done on the shell input before any  other  expansion
       except  history  expansion.   Therefore, if an alias is defined for the
       word foo, alias expansion may be avoided by quoting part of  the  word,
       e.g.  \foo.  But there is nothing to prevent an alias being defined for
       \foo as well.


QUOTING

       A character may be quoted (that is, made to stand for itself)  by  pre-
       ceding it with a ‘\’.  ‘\’ followed by a newline is ignored.

       A string enclosed between ‘$’ and ‘’ is processed the same way as the
       string arguments of the print builtin, and the resulting string is con-
       sidered to be entirely quoted.  A literal ‘’ character can be included
       in the string by using the ‘\’ escape.

       All characters enclosed between a pair of single quotes  ()  that  is
       not  preceded by a ‘$’ are quoted.  A single quote cannot appear within
       single quotes unless the option RC_QUOTES is set, in which case a  pair
       of single quotes are turned into a single quote.  For example,

              print 

       outputs  nothing  apart from a newline if RC_QUOTES is not set, but one
       single quote if it is set.

       Inside double quotes (""), parameter and  command  substitution  occur,
       and ‘\’ quotes the characters ‘\’, ‘’, ‘"’, and ‘$’.


REDIRECTION

       If  a  command is followed by & and job control is not active, then the
       default standard input for the command is  the  empty  file  /dev/null.
       Otherwise,  the environment for the execution of a command contains the
       file descriptors of the invoking  shell  as  modified  by  input/output
       specifications.

       The following may appear anywhere in a simple command or may precede or
       follow a complex command.  Expansion occurs before  word  or  digit  is
       used except as noted below.  If the result of substitution on word pro-
       duces more than one filename,  redirection  occurs  for  each  separate
       filename in turn.

       < word Open file word for reading as standard input.

       <> word
              Open  file  word  for reading and writing as standard input.  If
              the file does not exist then it is created.

       > word Open file word for writing as standard output.  If the file does
              not exist then it is created.  If the file exists, and the CLOB-
              BER option is unset, this causes  an  error;  otherwise,  it  is
              truncated to zero length.

       >| word
       >! word
              Same  as  >, except that the file is truncated to zero length if
              it exists, even if CLOBBER is unset.

       >> word
              Open file word for writing in append mode  as  standard  output.
              If  the  file  does  not exist, and the CLOBBER option is unset,
              this causes an error; otherwise, the file is created.

       >>| word
       >>! word
              Same as >>, except that the file  is  created  if  it  does  not
              exist, even if CLOBBER is unset.

       <<[-] word
              The  shell  input is read up to a line that is the same as word,
              or to an end-of-file.  No parameter expansion, command substitu-
              tion or filename generation is performed on word.  The resulting
              document, called a here-document, becomes the standard input.

              If any character of word is quoted with single or double  quotes
              or a ‘\’, no interpretation is placed upon the characters of the
              document.  Otherwise, parameter and command substitution occurs,
              ‘\’  followed  by  a newline is removed, and ‘\’ must be used to
              quote the characters ‘\’, ‘$’, ‘’ and the  first  character  of
              word.

              Note  that  word itself does not undergo shell expansion.  Back-
              quotes in word do not have  their  usual  effect;  instead  they
              behave  similarly  to  double quotes, except that the backquotes
              themselves are passed through unchanged.  (This  information  is
              given for completeness and it is not recommended that backquotes
              be used.)  Quotes in the form $... have their standard  effect
              of expanding backslashed references to special characters.

              If <<- is used, then all leading tabs are stripped from word and
              from the document.

       <<< word
              Perform shell expansion on word and pass the result to  standard
              input.  This is known as a here-string.  Compare the use of word
              in here-documents above,  where  word  does  not  undergo  shell
              expansion.

       <& number
       >& number
              The  standard  input/output  is  duplicated from file descriptor
              number (see dup2(2)).

       <& -
       >& -   Close the standard input/output.

       <& p
       >& p   The input/output from/to the coprocess is moved to the  standard
              input/output.

       >& word
       &> word
              (Except  where ‘>& word’ matches one of the above syntaxes; ‘&>’
              can always be used to avoid  this  ambiguity.)   Redirects  both
              standard  output  and  standard error (file descriptor 2) in the
              manner of ‘> word’.  Note that  this  does  not  have  the  same
              effect as ‘> word 2>&1’ in the presence of multios (see the sec-
              tion below).

       >&| word
       >&! word
       &>| word
       &>! word
              Redirects both standard output and standard error (file descrip-
              tor 2) in the manner of ‘>| word’.

       >>& word
       &>> word
              Redirects both standard output and standard error (file descrip-
              tor 2) in the manner of ‘>> word’.

       >>&| word
       >>&! word
       &>>| word
       &>>! word
              Redirects both standard output and standard error (file descrip-
              tor 2) in the manner of ‘>>| word’.

       If  one  of  the above is preceded by a digit, then the file descriptor
       referred to is that specified by the digit instead of the default 0  or
       1.   The order in which redirections are specified is significant.  The
       shell evaluates each redirection in  terms  of  the  (file  descriptor,
       file) association at the time of evaluation.  For example:

              ... 1>fname 2>&1

       first associates file descriptor 1 with file fname.  It then associates
       file descriptor 2 with the file associated with file descriptor 1 (that
       is,  fname).  If the order of redirections were reversed, file descrip-
       tor 2 would be associated with the terminal (assuming file descriptor 1
       had  been)  and  then  file  descriptor 1 would be associated with file
       fname.

       The ‘|&’ command separator described in Simple Commands & Pipelines  in
       zshmisc(1) is a shorthand for ‘2>&1 |’.

       For output redirections only, if word is of the form ‘>(list)’ then the
       output is piped to the command represented by list.  See  Process  Sub-
       stitution in zshexpn(1).


MULTIOS

       If the user tries to open a file descriptor for writing more than once,
       the shell opens the file descriptor as a pipe to a process that  copies
       its  input  to  all the specified outputs, similar to tee, provided the
       MULTIOS option is set, as it is by default.  Thus:

              date >foo >bar

       writes the date to two files, named ‘foo’ and ‘bar’.  Note that a  pipe
       is an implicit redirection; thus

              date >foo | cat

       writes the date to the file ‘foo’, and also pipes it to cat.

       If  the MULTIOS option is set, the word after a redirection operator is
       also subjected to filename generation (globbing).  Thus

              : > *

       will truncate all files in the current directory, assuming  there’s  at
       least  one.  (Without the MULTIOS option, it would create an empty file
       called ‘*’.)  Similarly, you can do

              echo exit 0 >> *.sh

       If the user tries to open a file descriptor for reading more than once,
       the  shell opens the file descriptor as a pipe to a process that copies
       all the specified inputs to its output in the order specified,  similar
       to cat, provided the MULTIOS option is set.  Thus

              sort <foo <fubar

       or even

              sort <f{oo,ubar}

       is equivalent to ‘cat foo fubar | sort’.

       Note that a pipe is an implicit redirection; thus

              cat bar | sort <foo

       is equivalent to ‘cat bar foo | sort’ (note the order of the inputs).

       If  the MULTIOS option is unset, each redirection replaces the previous
       redirection for that file descriptor.  However, all files redirected to
       are actually opened, so

              echo foo > bar > baz

       when MULTIOS is unset will truncate bar, and write ‘foo’ into baz.

       There  is  a  problem  when an output multio is attached to an external
       program.  A simple example shows this:

              cat file >file1 >file2
              cat file1 file2

       Here, it is possible that the second ‘cat’ will not  display  the  full
       contents  of  file1  and  file2  (i.e.  the  original  contents of file
       repeated twice).

       The reason for this is that the multios are spawned after the cat  pro-
       cess is forked from the parent shell, so the parent shell does not wait
       for the multios to finish writing data.   This  means  the  command  as
       shown  can  exit  before  file1 and file2 are completely written.  As a
       workaround, it is possible to run the cat process as part of a  job  in
       the current shell:

              { cat file } >file >file2

       Here, the {...} job will pause to wait for both files to be written.



REDIRECTIONS WITH NO COMMAND

       When a simple command consists of one or more redirection operators and
       zero or more parameter assignments, but no command name, zsh can behave
       in several ways.

       If  the  parameter NULLCMD is not set or the option CSH_NULLCMD is set,
       an error is caused.  This is the csh behavior and CSH_NULLCMD is set by
       default when emulating csh.

       If  the option SH_NULLCMD is set, the builtin ‘:’ is inserted as a com-
       mand with the given redirections.  This is the default  when  emulating
       sh or ksh.

       Otherwise, if the parameter NULLCMD is set, its value will be used as a
       command with the given redirections.  If both NULLCMD  and  READNULLCMD
       are  set,  then the value of the latter will be used instead of that of
       the former when the redirection is an input.  The default  for  NULLCMD
       is ‘cat’ and for READNULLCMD is ‘more’. Thus

              < file

       shows the contents of file on standard output, with paging if that is a
       terminal.  NULLCMD and READNULLCMD may refer to shell functions.



COMMAND EXECUTION

       If a command name contains no slashes, the shell attempts to locate it.
       If  there exists a shell function by that name, the function is invoked
       as described in the section  ‘Functions’.   If  there  exists  a  shell
       builtin by that name, the builtin is invoked.

       Otherwise,  the  shell  searches  each element of $path for a directory
       containing an executable file by that name.  If the  search  is  unsuc-
       cessful,  the  shell prints an error message and returns a nonzero exit
       status.

       If execution fails because the file is not in  executable  format,  and
       the  file  is  not  a  directory,  it  is assumed to be a shell script.
       /bin/sh is spawned to execute it.  If the program is a  file  beginning
       with ‘#!’, the remainder of the first line specifies an interpreter for
       the program.  The shell will execute the specified interpreter on oper-
       ating  systems that do not handle this executable format in the kernel.


FUNCTIONS

       Shell functions are defined with the function reserved word or the spe-
       cial  syntax  ‘funcname  ()’.   Shell  functions are read in and stored
       internally.  Alias names are resolved when the function is read.  Func-
       tions  are  executed  like  commands with the arguments passed as posi-
       tional parameters.  (See the section ‘Command Execution’.)

       Functions execute in the same process as the caller and share all files
       and  present  working  directory  with  the caller.  A trap on EXIT set
       inside a function is executed after the function completes in the envi-
       ronment of the caller.

       The return builtin is used to return from function calls.

       Function  identifiers  can be listed with the functions builtin.  Func-
       tions can be undefined with the unfunction builtin.


AUTOLOADING FUNCTIONS

       A function can be marked as undefined using the  autoload  builtin  (or
       ‘functions  -u’  or ‘typeset -fu’).  Such a function has no body.  When
       the function is first executed, the shell searches for  its  definition
       using the elements of the fpath variable.  Thus to define functions for
       autoloading, a typical sequence is:

              fpath=(~/myfuncs $fpath)
              autoload myfunc1 myfunc2 ...

       The usual alias expansion during reading  will  be  suppressed  if  the
       autoload builtin or its equivalent is given the option -U. This is rec-
       ommended for the use of functions supplied with the  zsh  distribution.
       Note  that  for functions precompiled with the zcompile builtin command
       the flag -U must be provided when the .zwc file is created, as the cor-
       responding information is compiled into the latter.

       For  each  element  in fpath, the shell looks for three possible files,
       the newest of which is used to load the definition for the function:

       element.zwc
              A file created with  the  zcompile  builtin  command,  which  is
              expected  to  contain  the  definitions for all functions in the
              directory named element.  The file is treated in the same manner
              as  a  directory  containing files for functions and is searched
              for the definition of the function.   If the definition  is  not
              found,  the  search for a definition proceeds with the other two
              possibilities described below.

              If element already includes a .zwc extension (i.e. the extension
              was  explicitly  given by the user), element is searched for the
              definition of the function without comparing its age to that  of
              other  files;  in  fact, there does not need to be any directory
              named element without the suffix.   Thus  including  an  element
              such as ‘/usr/local/funcs.zwc’ in fpath will speed up the search
              for functions, with the  disadvantage  that  functions  included
              must  be  explicitly recompiled by hand before the shell notices
              any changes.

       element/function.zwc
              A file created with zcompile, which is expected to  contain  the
              definition  for function.  It may include other function defini-
              tions as well, but those are neither loaded nor executed; a file
              found  in  this way is searched only for the definition of func-
              tion.

       element/function
              A file of zsh command text, taken to be the definition for func-
              tion.

       In  summary, the order of searching is, first, in the parents of direc-
       tories in fpath for the newer of  either  a  compiled  directory  or  a
       directory  in fpath; second, if more than one of these contains a defi-
       nition for the function that is sought, the leftmost in  the  fpath  is
       chosen;  and  third, within a directory, the newer of either a compiled
       function or an ordinary function definition is used.

       If the KSH_AUTOLOAD option is set, or the file contains only  a  simple
       definition of the function, the file’s contents will be executed.  This
       will normally define the function in question,  but  may  also  perform
       initialization, which is executed in the context of the function execu-
       tion, and may therefore define local parameters.  It is an error if the
       function is not defined by loading the file.

       Otherwise,  the  function body (with no surrounding ‘funcname() {...}’)
       is taken to be the complete contents of the file.  This form allows the
       file  to be used directly as an executable shell script.  If processing
       of the file results in the  function  being  re-defined,  the  function
       itself  is  not re-executed.  To force the shell to perform initializa-
       tion and then call the function defined, the file should  contain  ini-
       tialization code (which will be executed then discarded) in addition to
       a complete function definition (which will be retained  for  subsequent
       calls to the function), and a call to the shell function, including any
       arguments, at the end.

       For example, suppose the autoload file func contains

              func() { print This is func; }
              print func is initialized

       then ‘func; func’ with KSH_AUTOLOAD set will produce both  messages  on
       the  first  call, but only the message ‘This is func’ on the second and
       subsequent calls.   Without  KSH_AUTOLOAD  set,  it  will  produce  the
       initialization  message on the first call, and the other message on the
       second and subsequent calls.

       It is also possible  to  create  a  function  that  is  not  marked  as
       autoloaded,  but  which loads its own definition by searching fpath, by
       using ‘autoload -X’ within a shell function.  For example, the  follow-
       ing are equivalent:

              myfunc() {
                autoload -X
              }
              myfunc args...

       and

              unfunction myfunc   # if myfunc was defined
              autoload myfunc
              myfunc args...

       In  fact,  the  functions  command outputs ‘builtin autoload -X’ as the
       body of an autoloaded function.  This is done so that

              eval "$(functions)"

       produces a reasonable result.  A true autoloaded function can be  iden-
       tified  by  the  presence  of  the  comment  ‘# undefined’ in the body,
       because all comments are discarded from defined functions.

       To load the definition of an autoloaded function myfunc without execut-
       ing myfunc, use:

              autoload +X myfunc



SPECIAL FUNCTIONS

       The following functions, if defined, have special meaning to the shell:

       chpwd  Executed whenever the current working directory is changed.

       periodic
              If the parameter PERIOD is set, this function is executed  every
              $PERIOD seconds, just before a prompt.

       precmd Executed before each prompt.

       preexec
              Executed  just  after a command has been read and is about to be
              executed.  If the history mechanism is active (and the line  was
              not discarded from the history buffer), the string that the user
              typed is passed as the first argument, otherwise it is an  empty
              string.   The  actual  command  that will be executed (including
              expanded aliases) is passed in two different forms:  the  second
              argument  is  a single-line, size-limited version of the command
              (with things like function bodies elided);  the  third  argument
              contains the full text that is being executed.

       TRAPNAL
              If defined and non-null, this function will be executed whenever
              the shell catches a signal SIGNAL, where NAL is a signal name as
              specified  for  the  kill  builtin.   The  signal number will be
              passed as the first parameter to the function.

              If a function of this form is defined and null,  the  shell  and
              processes spawned by it will ignore SIGNAL.

              The  return value from the function is handled specially.  If it
              is zero, the signal is assumed to have been handled, and  execu-
              tion  continues  normally.   Otherwise, the normal effect of the
              signal is produced; if this causes execution to  terminate,  the
              status  returned  to  the  shell is the status returned from the
              function.

              Programs terminated by uncaught  signals  typically  return  the
              status  128  plus the signal number.  Hence the following causes
              the handler for SIGINT to print a message, then mimic the  usual
              effect of the signal.

                     TRAPINT() {
                       print "Caught SIGINT, aborting."
                       return $(( 128 + $1 ))
                     }

              The  functions  TRAPZERR,  TRAPDEBUG and TRAPEXIT are never exe-
              cuted inside other traps.

       TRAPDEBUG
              Executed after each command.

       TRAPEXIT
              Executed when the shell exits,  or  when  the  current  function
              exits if defined inside a function.

       TRAPZERR
              Executed  whenever  a  command has a non-zero exit status.  How-
              ever, the function is not executed if the command occurred in  a
              sublist  followed  by  ‘&&’ or ‘||’; only the final command in a
              sublist of this type causes the trap to be executed.

       The functions beginning ‘TRAP’ may alternatively be  defined  with  the
       trap  builtin:   this may be preferable for some uses, as they are then
       run in the environment of the calling process, rather than in their own
       function  environment.   Apart from the difference in calling procedure
       and the fact that the function form appears in lists of functions,  the
       forms

              TRAPNAL() {
               # code
              }

       and

              trap 
               # code

       are equivalent.


JOBS

       If  the  MONITOR  option  is set, an interactive shell associates a job
       with each pipeline.  It keeps a table of current jobs, printed  by  the
       jobs  command,  and  assigns them small integer numbers.  When a job is
       started asynchronously with ‘&’, the shell prints a  line  to  standard
       error which looks like:

              [1] 1234

       indicating that the job which was started asynchronously was job number
       1 and had one (top-level) process, whose process ID was 1234.

       If a job is started with ‘&|’ or ‘&!’, then  that  job  is  immediately
       disowned.   After  startup,  it does not have a place in the job table,
       and is not subject to the job control features described here.

       If you are running a job and wish to do something else you may hit  the
       key  ^Z (control-Z) which sends a TSTP signal to the current job:  this
       key may be redefined by the susp option of the external  stty  command.
       The  shell  will  then  normally  indicate  that the job has been ‘sus-
       pended’, and print another prompt.  You can then manipulate  the  state
       of  this  job, putting it in the background with the bg command, or run
       some other commands and then eventually bring the  job  back  into  the
       foreground  with  the foreground command fg.  A ^Z takes effect immedi-
       ately and is like an interrupt in that pending output and unread  input
       are discarded when it is typed.

       A job being run in the background will suspend if it tries to read from
       the terminal.  Background jobs are normally allowed to produce  output,
       but  this  can be disabled by giving the command ‘stty tostop’.  If you
       set this tty option, then background jobs will suspend when they try to
       produce output like they do when they try to read input.

       When  a  command  is  suspended and continued later with the fg or wait
       builtins, zsh restores tty modes that were in effect when it  was  sus-
       pended.   This (intentionally) does not apply if the command is contin-
       ued via ‘kill -CONT’, nor when it is continued with bg.

       There are several ways to refer to jobs in the shell.   A  job  can  be
       referred  to  by  the process ID of any process of the job or by one of
       the following:

       %number
              The job with the given number.
       %string
              Any job whose command line begins with string.
       %?string
              Any job whose command line contains string.
       %%     Current job.
       %+     Equivalent to ‘%%’.
       %-     Previous job.

       The shell learns immediately whenever a process changes state.  It nor-
       mally  informs  you  whenever  a job becomes blocked so that no further
       progress is possible.  If the NOTIFY option is not set, it waits  until
       just before it prints a prompt before it informs you.  All such notifi-
       cations are sent directly to the terminal, not to the  standard  output
       or standard error.

       When  the  monitor mode is on, each background job that completes trig-
       gers any trap set for CHLD.

       When you try to leave the shell while jobs are  running  or  suspended,
       you  will  be warned that ‘You have suspended (running) jobs’.  You may
       use the jobs command to see what they are.  If you do this  or  immedi-
       ately try to exit again, the shell will not warn you a second time; the
       suspended jobs will be terminated, and the running jobs will be sent  a
       SIGHUP signal, if the HUP option is set.

       To  avoid  having  the shell terminate the running jobs, either use the
       nohup command (see nohup(1)) or the disown builtin.


SIGNALS

       The INT and QUIT signals for an invoked command are ignored if the com-
       mand  is  followed by ‘&’ and the MONITOR option is not active.  Other-
       wise, signals have the values inherited by the shell  from  its  parent
       (but see the TRAPNAL special functions in the section ‘Functions’).


ARITHMETIC EVALUATION

       The  shell  can  perform  integer and floating point arithmetic, either
       using the builtin let, or via a substitution of the form $((...)).  For
       integers,  the  shell is usually compiled to use 8-byte precision where
       this is available, otherwise precision is 4 bytes.  This can be tested,
       for example, by giving the command ‘print - $(( 12345678901 ))’; if the
       number appears unchanged, the precision is at least 8 bytes.   Floating
       point arithmetic is always double precision.

       The let builtin command takes arithmetic expressions as arguments; each
       is evaluated separately.  Since many of the  arithmetic  operators,  as
       well  as  spaces, require quoting, an alternative form is provided: for
       any command which begins with a ‘((’, all the characters until a match-
       ing  ‘))’  are  treated as a quoted expression and arithmetic expansion
       performed as for an argument of  let.   More  precisely,  ‘((...))’  is
       equivalent to ‘let "..."’.  For example, the following statement

              (( val = 2 + 1 ))

       is equivalent to

              let "val = 2 + 1"

       both  assigning  the  value 3 to the shell variable val and returning a
       zero status.

       Integers can be in bases other than 10.  A leading ‘0x’ or ‘0X’ denotes
       hexadecimal.   Integers may also be of the form ‘base#n’, where base is
       a decimal number between two and thirty-six representing the arithmetic
       base  and  n  is  a number in that base (for example, ‘16#ff’ is 255 in
       hexadecimal).  The base# may also be omitted, in which case base 10  is
       used.  For backwards compatibility the form ‘[base]n’ is also accepted.

       It is also possible to specify a base to be used for output in the form
       ‘[#base]’,  for  example  ‘[#16]’.  This is used when outputting arith-
       metical substitutions or when assigning to scalar  parameters,  but  an
       explicitly  defined  integer  or  floating  point parameter will not be
       affected.  If an integer variable is implicitly defined  by  an  arith-
       metic  expression,  any  base  specified in this way will be set as the
       variable’s output arithmetic base as if the option  ‘-i  base’  to  the
       typeset builtin had been used.  The expression has no precedence and if
       it occurs more than once in a mathematical expression, the last encoun-
       tered  is  used.   For  clarity it is recommended that it appear at the
       beginning of an expression.  As an example:

              typeset -i 16 y
              print $(( [#8] x = 32, y = 32 ))
              print $x $y

       outputs first ‘8#40’, the rightmost value in the given output base, and
       then  ‘8#40 16#20’, because y has been explicitly declared to have out-
       put base 16, while x (assuming it does not already exist) is implicitly
       typed  by  the arithmetic evaluation, where it acquires the output base
       8.

       If the C_BASES option is set, hexadecimal numbers  in  the  standard  C
       format,  for  example 0xFF instead of the usual ‘16#FF’.  If the option
       OCTAL_ZEROES is also set (it is not by default), octal numbers will  be
       treated  similarly  and  hence appear as ‘077’ instead of ‘8#77’.  This
       option has no effect on the output of bases other than hexadecimal  and
       octal, and these formats are always understood on input.

       When  an output base is specified using the ‘[#base]’ syntax, an appro-
       priate base prefix will be output if necessary, so that the value  out-
       put  is  valid  syntax  for  input.   If  the # is doubled, for example
       ‘[##16]’, then no base prefix is output.

       Floating point constants are recognized by the presence  of  a  decimal
       point  or an exponent.  The decimal point may be the first character of
       the constant, but the exponent character e or E may not, as it will  be
       taken for a parameter name.

       An  arithmetic  expression uses nearly the same syntax, precedence, and
       associativity of expressions in C.  The following  operators  are  sup-
       ported (listed in decreasing order of precedence):

       + - ! ~ ++ --
              unary plus/minus, logical NOT, complement, {pre,post}{in,de}cre-
              ment
       << >>  bitwise shift left, right
       &      bitwise AND
       ^      bitwise XOR
       |      bitwise OR
       **     exponentiation
       * / %  multiplication, division, modulus (remainder)
       + -    addition, subtraction
       < > <= >=
              comparison
       == !=  equality and inequality
       &&     logical AND
       || ^^  logical OR, XOR
       ? :    ternary operator
       = += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=
              assignment
       ,      comma operator

       The operators ‘&&’, ‘||’, ‘&&=’, and ‘||=’  are  short-circuiting,  and
       only  one of the latter two expressions in a ternary operator is evalu-
       ated.  Note the precedence of the bitwise AND, OR, and XOR operators.

       Mathematical functions can be  called  with  the  syntax  ‘func(args)’,
       where  the  function  decides  if  the  args  is  used as a string or a
       comma-separated list of arithmetic  expressions.  The  shell  currently
       defines  no mathematical functions by default, but the module zsh/math-
       func may be loaded with the zmodload builtin to provide standard float-
       ing point mathematical functions.

       An  expression of the form ‘##x’ where x is any character sequence such
       as ‘a’, ‘^A’, or ‘\M-\C-x’ gives the ASCII value of this character  and
       an  expression  of  the  form ‘#foo’ gives the ASCII value of the first
       character of the value of the parameter foo.  Note that this is differ-
       ent  from  the  expression  ‘$#foo’,  a standard parameter substitution
       which gives the length of the parameter foo.  ‘#\’ is accepted  instead
       of ‘##’, but its use is deprecated.

       Named  parameters  and  subscripted  arrays  can  be referenced by name
       within an arithmetic expression without using the  parameter  expansion
       syntax.  For example,

              ((val2 = val1 * 2))

       assigns twice the value of $val1 to the parameter named val2.

       An  internal  integer representation of a named parameter can be speci-
       fied with the integer builtin.  Arithmetic evaluation is  performed  on
       the  value  of each assignment to a named parameter declared integer in
       this manner.  Assigning a floating point number to an  integer  results
       in rounding down to the next integer.

       Likewise,  floating  point  numbers  can  be  declared  with  the float
       builtin; there are two types, differing only in their output format, as
       described  for  the typeset builtin.  The output format can be bypassed
       by using arithmetic substitution instead of the parameter substitution,
       i.e.  ‘${float}’  uses  the  defined  format,  but  ‘$((float))’ uses a
       generic floating point format.

       Promotion of integer to floating point values is performed where neces-
       sary.   In  addition,  if  any operator which requires an integer (‘~’,
       ‘&’, ‘|’, ‘^’, ‘%’, ‘<<’, ‘>>’ and their equivalents  with  assignment)
       is given a floating point argument, it will be silently rounded down to
       the next integer.

       Scalar variables can hold integer or floating point values at different
       times; there is no memory of the numeric type in this case.

       If a variable is first assigned in a numeric context without previously
       being declared, it will be implicitly typed as  integer  or  float  and
       retain  that  type either until the type is explicitly changed or until
       the end of the scope.  This  can  have  unforeseen  consequences.   For
       example, in the loop

              for (( f = 0; f < 1; f += 0.1 )); do
              # use $f
              done

       if  f has not already been declared, the first assignment will cause it
       to be created as an integer, and consequently the operation ‘f +=  0.1’
       will  always cause the result to be truncated to zero, so that the loop
       will fail.  A simple fix would be to turn the initialization into ‘f  =
       0.0’.   It is therefore best to declare numeric variables with explicit
       types.


CONDITIONAL EXPRESSIONS

       A conditional expression is used with the [[ compound command  to  test
       attributes  of  files  and  to compare strings.  Each expression can be
       constructed from one or more of the following unary or  binary  expres-
       sions:

       -a file
              true if file exists.

       -b file
              true if file exists and is a block special file.

       -c file
              true if file exists and is a character special file.

       -d file
              true if file exists and is a directory.

       -e file
              true if file exists.

       -f file
              true if file exists and is a regular file.

       -g file
              true if file exists and has its setgid bit set.

       -h file
              true if file exists and is a symbolic link.

       -k file
              true if file exists and has its sticky bit set.

       -n string
              true if length of string is non-zero.

       -o option
              true if option named option is on.  option may be a single char-
              acter, in which case it is a single letter  option  name.   (See
              the section ‘Specifying Options’.)

       -p file
              true if file exists and is a FIFO special file (named pipe).

       -r file
              true if file exists and is readable by current process.

       -s file
              true if file exists and has size greater than zero.

       -t fd  true  if file descriptor number fd is open and associated with a
              terminal device.  (note: fd is not optional)

       -u file
              true if file exists and has its setuid bit set.

       -w file
              true if file exists and is writable by current process.

       -x file
              true if file exists and is executable by  current  process.   If
              file  exists  and  is  a directory, then the current process has
              permission to search in the directory.

       -z string
              true if length of string is zero.

       -L file
              true if file exists and is a symbolic link.

       -O file
              true if file exists and is owned by the  effective  user  ID  of
              this process.

       -G file
              true if file exists and its group matches the effective group ID
              of this process.

       -S file
              true if file exists and is a socket.

       -N file
              true if file exists and its access time is not  newer  than  its
              modification time.

       file1 -nt file2
              true if file1 exists and is newer than file2.

       file1 -ot file2
              true if file1 exists and is older than file2.

       file1 -ef file2
              true if file1 and file2 exist and refer to the same file.

       string = pattern
       string == pattern
              true  if string matches pattern.  The ‘==’ form is the preferred
              one.  The ‘=’ form is for backward compatibility and  should  be
              considered obsolete.

       string != pattern
              true if string does not match pattern.

       string1 < string2
              true  if  string1  comes  before string2 based on ASCII value of
              their characters.

       string1 > string2
              true if string1 comes after string2  based  on  ASCII  value  of
              their characters.

       exp1 -eq exp2
              true if exp1 is numerically equal to exp2.

       exp1 -ne exp2
              true if exp1 is numerically not equal to exp2.

       exp1 -lt exp2
              true if exp1 is numerically less than exp2.

       exp1 -gt exp2
              true if exp1 is numerically greater than exp2.

       exp1 -le exp2
              true if exp1 is numerically less than or equal to exp2.

       exp1 -ge exp2
              true if exp1 is numerically greater than or equal to exp2.

       ( exp )
              true if exp is true.

       ! exp  true if exp is false.

       exp1 && exp2
              true if exp1 and exp2 are both true.

       exp1 || exp2
              true if either exp1 or exp2 is true.

       Normal  shell  expansion  is  performed on the file, string and pattern
       arguments, but the result of each expansion is constrained to be a sin-
       gle  word,  similar  to  the effect of double quotes.  However, pattern
       metacharacters are active for the pattern arguments; the  patterns  are
       the  same  as  those  used for filename generation, see zshexpn(1), but
       there is no special behaviour of ‘/’ nor  initial  dots,  and  no  glob
       qualifiers are allowed.

       In  each  of the above expressions, if file is of the form ‘/dev/fd/n’,
       where n is an integer, then the test applied to  the  open  file  whose
       descriptor  number is n, even if the underlying system does not support
       the /dev/fd directory.

       In the forms which do numeric comparison, the expressions  exp  undergo
       arithmetic expansion as if they were enclosed in $((...)).

       For example, the following:

              [[ ( -f foo || -f bar ) && $report = y* ]] && print File exists.

       tests if either file foo or file bar exists, and if so, if the value of
       the parameter report begins with ‘y’;  if  the  complete  condition  is
       true, the message ‘File exists.’ is printed.


PROMPT EXPANSION

       Prompt  sequences  undergo  a  special form of expansion.  This type of
       expansion is also available using the -P option to the print builtin.

       If the PROMPT_SUBST option is set, the prompt string is first subjected
       to  parameter expansion, command substitution and arithmetic expansion.
       See zshexpn(1).

       Certain escape sequences may be recognised in the prompt string.

       If the PROMPT_BANG option is set, a ‘!’ in the prompt  is  replaced  by
       the  current  history  event  number.  A literal ‘!’ may then be repre-
       sented as ‘!!’.

       If the PROMPT_PERCENT option is  set,  certain  escape  sequences  that
       start  with  ‘%’  are  expanded.  Some escapes take an optional integer
       argument, which should appear between the ‘%’ and the next character of
       the sequence.  The following escape sequences are recognized:


   Special characters
       %%     A ‘%’.

       %)     A ‘)’.


   Login information
       %l     The line (tty) the user is logged in on, without ‘/dev/’ prefix.
              If the name starts with ‘/dev/tty’, that prefix is stripped.

       %M     The full machine hostname.

       %m     The hostname up to the first ‘.’.  An integer may follow the ‘%’
              to  specify  how  many  components  of the hostname are desired.
              With a negative integer, trailing components of the hostname are
              shown.

       %n     $USERNAME.

       %y     The line (tty) the user is logged in on, without ‘/dev/’ prefix.
              This does not treat ‘/dev/tty’ names specially.


   Shell state
       %#     A ‘#’ if the shell is running with privileges,  a  ‘%’  if  not.
              Equivalent  to ‘%(!.#.%%)’.  The definition of ‘privileged’, for
              these purposes, is that either the effective user  ID  is  zero,
              or,  if  POSIX.1e  capabilities are supported, that at least one
              capability is raised in  either  the  Effective  or  Inheritable
              capability vectors.

       %?     The  return  code  of  the last command executed just before the
              prompt.

       %_     The status of the parser, i.e. the shell constructs  (like  ‘if’
              and  ‘for’) that have been started on the command line. If given
              an integer number that many strings will  be  printed;  zero  or
              negative  or  no integer means print as many as there are.  This
              is most useful in prompts PS2 for continuation lines and PS4 for
              debugging  with  the  XTRACE  option; in the latter case it will
              also work non-interactively.

       %d
       %/     Present working directory ($PWD).  If  an  integer  follows  the
              ‘%’,  it  specifies  a  number of trailing components of $PWD to
              show; zero means the whole path.  A negative  integer  specifies
              leading components, i.e. %-1d specifies the first component.

       %~     As  %d  and %/, but if $PWD has a named directory as its prefix,
              that part is replaced by a ‘~’  followed  by  the  name  of  the
              directory.   If it starts with $HOME, that part is replaced by a
              ‘~’.

       %h
       %!     Current history event number.

       %i     The line number currently being executed in the script,  sourced
              file,  or  shell  function given by %N.  This is most useful for
              debugging as part of $PS4.

       %j     The number of jobs.

       %L     The current value of $SHLVL.

       %N     The name of the script, sourced file, or shell function that zsh
              is currently executing, whichever was started most recently.  If
              there is none, this is equivalent to the parameter $0.  An inte-
              ger may follow the ‘%’ to specify a number of trailing path com-
              ponents to show; zero means the full path.  A  negative  integer
              specifies leading components.

       %c
       %.
       %C     Trailing  component  of  $PWD.  An integer may follow the ‘%’ to
              get more than one component.  Unless ‘%C’ is  used,  tilde  con-
              traction  is performed first.  These are deprecated as %c and %C
              are equivalent to %1~ and %1/, respectively, while explicit pos-
              itive  integers  have  the  same  effect  as  for the latter two
              sequences.


   Date and time
       %D     The date in yy-mm-dd format.

       %T     Current time of day, in 24-hour format.

       %t
       %@     Current time of day, in 12-hour, am/pm format.

       %*     Current time of day in 24-hour format, with seconds.

       %w     The date in day-dd format.

       %W     The date in mm/dd/yy format.

       %D{string}
              string is formatted using  the  strftime  function.   See  strf-
              time(3) for more details.  Three additional codes are available:
              %f prints the day of the month, like %e but without any  preced-
              ing  space if the day is a single digit, and %K/%L correspond to
              %k/%l for the hour of the day (24/12 hour  clock)  in  the  same
              way.


   Visual effects
       %B (%b)
              Start (stop) boldface mode.

       %E     Clear to end of line.

       %U (%u)
              Start (stop) underline mode.

       %S (%s)
              Start (stop) standout mode.

       %{...%}
              Include  a  string  as  a  literal  escape sequence.  The string
              within the braces should not change the cursor position.   Brace
              pairs can nest.


   Conditional substrings
       %v     The  value  of  the  first element of the psvar array parameter.
              Following the ‘%’ with an integer  gives  that  element  of  the
              array.  Negative integers count from the end of the array.

       %(x.true-text.false-text)
              Specifies  a  ternary expression.  The character following the x
              is arbitrary; the same character is used to  separate  the  text
              for  the  ‘true’  result from that for the ‘false’ result.  This
              separator may not appear in the true-text, except as part  of  a
              %-escape  sequence.  A ‘)’ may appear in the false-text as ‘%)’.
              true-text and false-text  may  both  contain  arbitrarily-nested
              escape sequences, including further ternary expressions.

              The  left  parenthesis may be preceded or followed by a positive
              integer n, which defaults to zero.  A negative integer  will  be
              multiplied  by  -1.  The test character x may be any of the fol-
              lowing:

              !      True if the shell is running with privileges.
              #      True if the effective uid of the current process is n.
              ?      True if the exit status of the last command was n.
              _      True if at least n shell constructs were started.
              C
              /      True if the current absolute path has at least n elements
                     relative  to  the root directory, hence / is counted as 0
                     elements.
              c
              .
              ~      True if the current path, with prefix replacement, has at
                     least  n elements relative to the root directory, hence /
                     is counted as 0 elements.
              D      True if the month is equal to n (January = 0).
              d      True if the day of the month is equal to n.
              g      True if the effective gid of the current process is n.
              j      True if the number of jobs is at least n.
              L      True if the SHLVL parameter is at least n.
              l      True if at least n characters have already  been  printed
                     on the current line.
              S      True if the SECONDS parameter is at least n.
              T      True if the time in hours is equal to n.
              t      True if the time in minutes is equal to n.
              v      True if the array psvar has at least n elements.
              w      True if the day of the week is equal to n (Sunday = 0).

       %<string<
       %>string>
       %[xstring]
              Specifies  truncation  behaviour for the remainder of the prompt
              string.   The  third,  deprecated,   form   is   equivalent   to
              ‘%xstringx’,  i.e.  x  may be ‘<’ or ‘>’.  The numeric argument,
              which in the third form may appear immediately  after  the  ‘[’,
              specifies  the  maximum  permitted length of the various strings
              that can be displayed in the prompt.  The string  will  be  dis-
              played  in  place  of  the truncated portion of any string; note
              this does not undergo prompt expansion.

              The forms with ‘<’ truncate at the left of the string,  and  the
              forms  with  ‘>’ truncate at the right of the string.  For exam-
              ple, if  the  current  directory  is  ‘/home/pike’,  the  prompt
              ‘%8<..<%/’  will expand to ‘..e/pike’.  In this string, the ter-
              minating character (‘<’, ‘>’ or ‘]’), or in fact any  character,
              may be quoted by a preceding ‘\’; note when using print -P, how-
              ever, that this must be doubled as the string is also subject to
              standard  print  processing,  in  addition  to  any  backslashes
              removed by a double quoted string:  the worst case is  therefore
              ‘print -P "%<\\\\<<..."’.

              If the string is longer than the specified truncation length, it
              will appear in full, completely replacing the truncated  string.

              The part of the prompt string to be truncated runs to the end of
              the string, or to the end of the next  enclosing  group  of  the
              ‘%(’  construct,  or  to  the next truncation encountered at the
              same grouping level (i.e. truncations inside a  ‘%(’  are  sepa-
              rate), which ever comes first.  In particular, a truncation with
              argument zero (e.g. ‘%<<’) marks the end of  the  range  of  the
              string  to  be truncated while turning off truncation from there
              on. For example, the prompt  ’%10<...<%~%<<%#  ’  will  print  a
              truncated representation of the current directory, followed by a
              ‘%’ or ‘#’, followed by a space.  Without the ‘%<<’,  those  two
              characters would be included in the string to be truncated.



zsh 4.2.1                       August 13, 2004                     ZSHMISC(1)

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