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UNIX Manual | Commands
							BASH_BUILTINS(1)					      BASH_BUILTINS(1)

NAME
       bash,  :,  .,  [, alias, bg, bind, break, builtin, caller, cd, command,
       compgen, complete, compopt,  continue,  declare,	 dirs,	disown,	 echo,
       enable,	eval,  exec, exit, export, false, fc, fg, getopts, hash, help,
       history, jobs, kill, let, local, logout, mapfile, popd, printf,	pushd,
       pwd,  read, readonly, return, set, shift, shopt, source, suspend, test,
       times, trap, true, type, typeset, ulimit, umask, unalias, unset, wait -
       bash built-in commands, see bash(1)

BASH BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by - accepts -- to signify the end of the
       options.	  The  :, true, false, and test builtins do not accept options
       and do not treat -- specially.  The exit, logout, break, continue, let,
       and  shift builtins accept and process arguments beginning with - with-
       out requiring --.  Other builtins that accept  arguments	 but  are  not
       specified  as accepting options interpret arguments beginning with - as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
	      No effect; the command does nothing beyond  expanding  arguments
	      and  performing any specified redirections.  A zero exit code is
	      returned.

	.  filename [arguments]
       source filename [arguments]
	      Read and execute commands from filename  in  the	current	 shell
	      environment  and return the exit status of the last command exe-
	      cuted from filename.  If filename does not contain a slash, file
	      names  in	 PATH  are used to find the directory containing file-
	      name.  The file searched for in PATH  need  not  be  executable.
	      When  bash  is  not  in  posix  mode,  the  current directory is
	      searched if no file is found in PATH.  If the sourcepath	option
	      to  the  shopt  builtin  command	is turned off, the PATH is not
	      searched.	 If any arguments are supplied, they become the	 posi-
	      tional  parameters  when	filename  is  executed.	 Otherwise the
	      positional parameters are unchanged.  The return status  is  the
	      status  of  the  last  command exited within the script (0 if no
	      commands are executed), and false if filename is	not  found  or
	      cannot be read.

       alias [-p] [name[=value] ...]
	      Alias with no arguments or with the -p option prints the list of
	      aliases in the form alias name=value on standard	output.	  When
	      arguments	 are supplied, an alias is defined for each name whose
	      value is given.  A trailing space in  value causes the next word
	      to be checked for alias substitution when the alias is expanded.
	      For each name in the argument list for which no  value  is  sup-
	      plied,  the  name	 and  value  of	 the  alias is printed.	 Alias
	      returns true unless a name is given for which no alias has  been
	      defined.

       bg [jobspec ...]
	      Resume  each  suspended  job jobspec in the background, as if it
	      had been started with &.	If jobspec is not present, the shell's
	      notion  of the current job is used.  bg jobspec returns 0 unless
	      run when job control is disabled or, when run with  job  control
	      enabled,	any  specified	jobspec	 was  not found or was started
	      without job control.

       bind [-m keymap] [-lpsvPSV]
       bind [-m keymap] [-q function] [-u function] [-r keyseq]
       bind [-m keymap] -f filename
       bind [-m keymap] -x keyseq:shell-command
       bind [-m keymap] keyseq:function-name
       bind readline-command
	      Display current readline key and function bindings, bind	a  key
	      sequence	to  a  readline	 function  or macro, or set a readline
	      variable.	 Each non-option argument is a	command	 as  it	 would
	      appear  in  .inputrc, but each binding or command must be passed
	      as a separate argument; e.g.,  '"\C-x\C-r":  re-read-init-file'.
	      Options, if supplied, have the following meanings:
	      -m keymap
		     Use keymap as the keymap to be affected by the subsequent
		     bindings.	Acceptable keymap names are emacs, emacs-stan-
		     dard,  emacs-meta,	 emacs-ctlx,  vi, vi-move, vi-command,
		     and vi-insert.  vi is equivalent to vi-command; emacs  is
		     equivalent to emacs-standard.
	      -l     List the names of all readline functions.
	      -p     Display  readline	function  names and bindings in such a
		     way that they can be re-read.
	      -P     List current readline function names and bindings.
	      -s     Display readline key sequences bound to  macros  and  the
		     strings  they  output  in such a way that they can be re-
		     read.
	      -S     Display readline key sequences bound to  macros  and  the
		     strings they output.
	      -v     Display  readline variable names and values in such a way
		     that they can be re-read.
	      -V     List current readline variable names and values.
	      -f filename
		     Read key bindings from filename.
	      -q function
		     Query about which keys invoke the named function.
	      -u function
		     Unbind all keys bound to the named function.
	      -r keyseq
		     Remove any current binding for keyseq.
	      -x keyseq:shell-command
		     Cause shell-command to be	executed  whenever  keyseq  is
		     entered.	When shell-command is executed, the shell sets
		     the READLINE_LINE variable to the contents of  the	 read-
		     line  line	 buffer and the READLINE_POINT variable to the
		     current location of the insertion point.  If the executed
		     command  changes  the  value  of  READLINE_LINE  or READ-
		     LINE_POINT, those new values will	be  reflected  in  the
		     editing state.

	      The  return value is 0 unless an unrecognized option is given or
	      an error occurred.

       break [n]
	      Exit from within a for, while, until, or select loop.  If	 n  is
	      specified, break n levels.  n must be >= 1.  If n is greater than
	      the number of enclosing loops, all enclosing loops  are  exited.
	      The  return  value  is  non-zero when n is <= 0; Otherwise, break
	      returns 0 value.

       builtin shell-builtin [arguments]
	      Execute the specified shell builtin, passing it  arguments,  and
	      return its exit status.  This is useful when defining a function
	      whose name is the same as a shell builtin, retaining  the	 func-
	      tionality of the builtin within the function.  The cd builtin is
	      commonly redefined this way.  The	 return	 status	 is  false  if
	      shell-builtin is not a shell builtin command.

       caller [expr]
	      Returns the context of any active subroutine call (a shell func-
	      tion or a script executed with the . or source builtins.	 With-
	      out expr, caller displays the line number and source filename of
	      the current subroutine call.  If a non-negative integer is  sup-
	      plied as expr, caller displays the line number, subroutine name,
	      and source file corresponding to that position  in  the  current
	      execution	 call  stack.  This extra information may be used, for
	      example, to print a stack trace.	The current frame is frame  0.
	      The  return  value is 0 unless the shell is not executing a sub-
	      routine call or expr does not correspond to a valid position  in
	      the call stack.

       cd [-L|-P] [dir]
	      Change  the  current directory to dir.  The variable HOME is the
	      default dir.  The variable CDPATH defines the  search  path  for
	      the  directory  containing  dir.	Alternative directory names in
	      CDPATH are separated by a colon (:).  A null directory  name  in
	      CDPATH  is  the  same as the current directory, i.e., ''.''.  If
	      dir begins with a slash (/), then CDPATH is  not	used.  The  -P
	      option  says  to use the physical directory structure instead of
	      following symbolic links (see also the  -P  option  to  the  set
	      builtin command); the -L option forces symbolic links to be fol-
	      lowed.  An argument of - is equivalent to $OLDPWD.   If  a  non-
	      empty  directory	name from CDPATH is used, or if - is the first
	      argument, and the directory change is successful,	 the  absolute
	      pathname of the new working directory is written to the standard
	      output.  The return value is true if the directory was  success-
	      fully changed; false otherwise.

       command [-pVv] command [arg ...]
	      Run  command  with  args	suppressing  the normal shell function
	      lookup. Only builtin commands or commands found in the PATH  are
	      executed.	  If the -p option is given, the search for command is
	      performed using a default value for PATH that is	guaranteed  to
	      find  all	 of  the  standard  utilities.	If either the -V or -v
	      option is supplied, a description of command is printed.	The -v
	      option  causes a single word indicating the command or file name
	      used to invoke command to be displayed; the -V option produces a
	      more  verbose  description.  If the -V or -v option is supplied,
	      the exit status is 0 if command was found, and  1	 if  not.   If
	      neither option is supplied and an error occurred or command can-
	      not be found, the exit status is 127.  Otherwise, the exit  sta-
	      tus of the command builtin is the exit status of command.

       compgen [option] [word]
	      Generate	possible  completion matches for word according to the
	      options, which may  be  any  option  accepted  by	 the  complete
	      builtin  with  the exception of -p and -r, and write the matches
	      to the standard output.  When using the -F or  -C	 options,  the
	      various  shell  variables	 set  by  the  programmable completion
	      facilities, while available, will not have useful values.

	      The matches will be generated in the same way  as	 if  the  pro-
	      grammable	 completion  code  had	generated them directly from a
	      completion specification with the same flags.  If word is speci-
	      fied, only those completions matching word will be displayed.

	      The  return  value is true unless an invalid option is supplied,
	      or no matches were generated.

       complete [-abcdefgjksuv] [-o comp-option] [-DE] [-A action]  [-G	 glob-
       pat] [-W wordlist] [-F function] [-C command]
	      [-X filterpat] [-P prefix] [-S suffix] name [name ...]
       complete -pr [-DE] [name ...]
	      Specify how arguments to each name should be completed.  If  the
	      -p  option  is supplied, or if no options are supplied, existing
	      completion specifications are printed in a way that allows  them
	      to be reused as input.  The -r option removes a completion spec-
	      ification for each name, or, if no names are supplied, all  com-
	      pletion  specifications.	 The  -D  option  indicates  that  the
	      remaining options and actions should apply  to  the  ''default''
	      command  completion;  that is, completion attempted on a command
	      for which no completion has previously  been  defined.   The  -E
	      option  indicates	 that the remaining options and actions should
	      apply to	''empty''  command  completion;	 that  is,  completion
	      attempted on a blank line.

	      The  process  of	applying  these completion specifications when
	      word completion is  attempted  is	 described  above  under  Pro-
	      grammable Completion.

	      Other  options,  if specified, have the following meanings.  The
	      arguments to the -G, -W, and -X options (and, if necessary,  the
	      -P  and -S options) should be quoted to protect them from expan-
	      sion before the complete builtin is invoked.
	      -o comp-option
		      The comp-option controls several aspects	of  the	 comp-
		      spec's  behavior beyond the simple generation of comple-
		      tions.  comp-option may be one of:
		      bashdefault
			      Perform the rest of the default bash completions
			      if the compspec generates no matches.
		      default Use  readline's  default	filename completion if
			      the compspec generates no matches.
		      dirnames
			      Perform directory name completion if  the	 comp-
			      spec generates no matches.
		      filenames
			      Tell  readline that the compspec generates file-
			      names, so it can perform	any  filename-specific
			      processing  (like	 adding	 a  slash to directory
			      names, quoting special characters, or  suppress-
			      ing  trailing spaces).  Intended to be used with
			      shell functions.
		      nospace Tell  readline  not  to  append  a  space	  (the
			      default)	to  words  completed at the end of the
			      line.
		      plusdirs
			      After any matches defined by  the	 compspec  are
			      generated,    directory	name   completion   is
			      attempted and  any  matches  are	added  to  the
			      results of the other actions.
	      -A action
		      The  action  may	be  one of the following to generate a
		      list of possible completions:
		      alias   Alias names.  May also be specified as -a.
		      arrayvar
			      Array variable names.
		      binding Readline key binding names.
		      builtin Names of shell builtin commands.	 May  also  be
			      specified as -b.
		      command Command names.  May also be specified as -c.
		      directory
			      Directory names.	May also be specified as -d.
		      disabled
			      Names of disabled shell builtins.
		      enabled Names of enabled shell builtins.
		      export  Names  of exported shell variables.  May also be
			      specified as -e.
		      file    File names.  May also be specified as -f.
		      function
			      Names of shell functions.
		      group   Group names.  May also be specified as -g.
		      helptopic
			      Help topics as accepted by the help builtin.
		      hostname
			      Hostnames, as taken from the file	 specified  by
			      the HOSTFILE shell variable.
		      job     Job  names,  if job control is active.  May also
			      be specified as -j.
		      keyword Shell reserved words.  May also be specified  as
			      -k.
		      running Names of running jobs, if job control is active.
		      service Service names.  May also be specified as -s.
		      setopt  Valid arguments for the -o  option  to  the  set
			      builtin.
		      shopt   Shell  option  names  as	accepted  by the shopt
			      builtin.
		      signal  Signal names.
		      stopped Names of stopped jobs, if job control is active.
		      user    User names.  May also be specified as -u.
		      variable
			      Names of all shell variables.  May also be spec-
			      ified as -v.
	      -G globpat
		      The pathname expansion pattern globpat  is  expanded  to
		      generate the possible completions.
	      -W wordlist
		      The  wordlist  is	 split using the characters in the IFS
		      special variable as delimiters, and each resultant  word
		      is  expanded.   The possible completions are the members
		      of the resultant list which match the  word  being  com-
		      pleted.
	      -C command
		      command  is  executed in a subshell environment, and its
		      output is used as the possible completions.
	      -F function
		      The shell function function is executed in  the  current
		      shell  environment.  When it finishes, the possible com-
		      pletions are retrieved from the value of	the  COMPREPLY
		      array variable.
	      -X filterpat
		      filterpat	 is  a pattern as used for pathname expansion.
		      It is applied to the list of possible completions gener-
		      ated  by	the  preceding options and arguments, and each
		      completion matching filterpat is removed from the	 list.
		      A	 leading  !  in filterpat negates the pattern; in this
		      case, any completion not matching filterpat is  removed.
	      -P prefix
		      prefix  is  added at the beginning of each possible com-
		      pletion after all other options have been applied.
	      -S suffix
		      suffix is appended to each possible completion after all
		      other options have been applied.

	      The  return  value is true unless an invalid option is supplied,
	      an option other than -p or -r is supplied without a  name	 argu-
	      ment,  an	 attempt  is made to remove a completion specification
	      for a name for which no specification exists, or an error occurs
	      adding a completion specification.

       compopt [-o option] [-DE] [+o option] [name]
	      Modify  completion  options  for	each  name  according  to  the
	      options, or for the currently-execution completion if  no	 names
	      are  supplied.   If no options are given, display the completion
	      options for each name or the current completion.	 The  possible
	      values  of  option  are  those  valid  for  the complete builtin
	      described above.	The -D option  indicates  that	the  remaining
	      options should apply to the ''default'' command completion; that
	      is, completion attempted on a command for	 which	no  completion
	      has  previously  been defined.  The -E option indicates that the
	      remaining options should apply to ''empty'' command  completion;
	      that is, completion attempted on a blank line.

       The  return  value  is  true  unless  an invalid option is supplied, an
       attempt is made to modify the options for a name for which  no  comple-
       tion specification exists, or an output error occurs.

       continue [n]
	      Resume the next iteration of the enclosing for, while, until, or
	      select loop.  If n is specified, resume  at  the	nth  enclosing
	      loop.   n	 must  be  >=  1.   If	n is greater than the number of
	      enclosing loops, the  last  enclosing  loop  (the	 ''top-level''
	      loop) is resumed.	 When continue is executed inside of loop, the
	      return value is non-zero when n  is  <=  0;  Otherwise,  continue
	      returns  0 value. When continue is executed outside of loop, the
	      return value is 0.

       declare [-aAfFilrtux] [-p] [name[=value] ...]
       typeset [-aAfFilrtux] [-p] [name[=value] ...]
	      Declare variables and/or give them attributes.  If no names  are
	      given  then display the values of variables.  The -p option will
	      display the attributes and values of each name.  When -p is used
	      with name arguments, additional options are ignored.  When -p is
	      supplied without name arguments, it will display the  attributes
	      and  values  of all variables having the attributes specified by
	      the additional options.  If no other options are	supplied  with
	      -p,  declare will display the attributes and values of all shell
	      variables.  The -f option will restrict  the  display  to	 shell
	      functions.  The -F option inhibits the display of function defi-
	      nitions; only the function name and attributes are printed.   If
	      the  extdebug  shell  option  is enabled using shopt, the source
	      file name and line number where the function is defined are dis-
	      played  as  well.	  The  -F  option  implies  -f.	 The following
	      options can be used to restrict output  to  variables  with  the
	      specified attribute or to give variables attributes:
	      -a     Each  name	 is  an	 indexed  array	 variable  (see Arrays
		     above).
	      -A     Each name is an associative array	variable  (see	Arrays
		     above).
	      -f     Use function names only.
	      -i     The variable is treated as an integer; arithmetic evalua-
		     tion (see ARITHMETIC EVALUATION above) is performed  when
		     the variable is assigned a value.
	      -l     When  the	variable  is  assigned a value, all upper-case
		     characters are converted to lower-case.   The  upper-case
		     attribute is disabled.
	      -r     Make names readonly.  These names cannot then be assigned
		     values by subsequent assignment statements or unset.
	      -t     Give each name the	 trace	attribute.   Traced  functions
		     inherit  the  DEBUG  and  RETURN  traps  from the calling
		     shell.  The trace attribute has no	 special  meaning  for
		     variables.
	      -u     When  the	variable  is  assigned a value, all lower-case
		     characters are converted to upper-case.   The  lower-case
		     attribute is disabled.
	      -x     Mark  names  for  export  to  subsequent commands via the
		     environment.

	      Using '+' instead of '-' turns off the attribute	instead,  with
	      the exceptions that +a may not be used to destroy an array vari-
	      able and +r will not remove the readonly attribute.   When  used
	      in a function, makes each name local, as with the local command.
	      If a variable name is followed by =value, the value of the vari-
	      able  is	set to value.  The return value is 0 unless an invalid
	      option is encountered, an attempt is made to define  a  function
	      using  ''-f foo=bar'', an attempt is made to assign a value to a
	      readonly variable, an attempt is made to assign a	 value	to  an
	      array variable without using the compound assignment syntax (see
	      Arrays above), one of the names is not a	valid  shell  variable
	      name, an attempt is made to turn off readonly status for a read-
	      only variable, an attempt is made to turn off array  status  for
	      an  array variable, or an attempt is made to display a non-exis-
	      tent function with -f.

       dirs [+n] [-n] [-cplv]
	      Without options,	displays  the  list  of	 currently  remembered
	      directories.   The  default  display  is	on  a single line with
	      directory names separated by spaces.  Directories are  added  to
	      the  list	 with  the  pushd  command;  the  popd command removes
	      entries from the list.
	      +n     Displays the nth entry counting from the left of the list
		     shown by dirs when invoked without options, starting with
		     zero.
	      -n     Displays the nth entry counting from  the	right  of  the
		     list shown by dirs when invoked without options, starting
		     with zero.
	      -c     Clears  the  directory  stack  by	deleting  all  of  the
		     entries.
	      -l     Produces  a  longer  listing;  the default listing format
		     uses a tilde to denote the home directory.
	      -p     Print the directory stack with one entry per line.
	      -v     Print the directory stack with one entry per  line,  pre-
		     fixing each entry with its index in the stack.

	      The  return value is 0 unless an invalid option is supplied or n
	      indexes beyond the end of the directory stack.

       disown [-ar] [-h] [jobspec ...]
	      Without options, each jobspec  is	 removed  from	the  table  of
	      active  jobs.   If jobspec is not present, and neither -a nor -r
	      is supplied, the shell's notion of the current job is used.   If
	      the -h option is given, each jobspec is not removed from the ta-
	      ble, but is marked so that SIGHUP is not sent to the job if  the
	      shell  receives a SIGHUP.	 If no jobspec is present, and neither
	      the -a nor the -r option is supplied, the current job  is	 used.
	      If no jobspec is supplied, the -a option means to remove or mark
	      all jobs; the -r option without  a  jobspec  argument  restricts
	      operation	 to running jobs.  The return value is 0 unless a job-
	      spec does not specify a valid job.

       echo [-neE] [arg ...]
	      Output the args, separated by spaces,  followed  by  a  newline.
	      The return status is always 0.  If -n is specified, the trailing
	      newline is suppressed.  If the -e option is  given,  interpreta-
	      tion  of	the following backslash-escaped characters is enabled.
	      The -E option disables the interpretation of these escape	 char-
	      acters,  even  on systems where they are interpreted by default.
	      The xpg_echo shell option may be used to	dynamically  determine
	      whether  or not echo expands these escape characters by default.
	      echo does not interpret -- to mean the  end  of  options.	  echo
	      interprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress further output
	      \e     an escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal tab
	      \v     vertical tab
	      \\     backslash
	      \0nnn  the  eight-bit  character	whose value is the octal value
		     nnn (zero to three octal digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (one or two hex digits)

       enable [-a] [-dnps] [-f filename] [name ...]
	      Enable  and disable builtin shell commands.  Disabling a builtin
	      allows a disk command which has the same name as a shell builtin
	      to  be  executed without specifying a full pathname, even though
	      the shell normally searches for builtins before  disk  commands.
	      If  -n  is  used,	 each  name  is disabled; otherwise, names are
	      enabled.	For example, to use the test binary found via the PATH
	      instead  of  the	shell builtin version, run ''enable -n test''.
	      The -f option means to load the new builtin  command  name  from
	      shared object filename, on systems that support dynamic loading.
	      The -d option will delete a builtin previously loaded  with  -f.
	      If no name arguments are given, or if the -p option is supplied,
	      a list of shell builtins is printed.  With no other option argu-
	      ments,  the  list consists of all enabled shell builtins.	 If -n
	      is supplied, only disabled builtins are printed.	If -a is  sup-
	      plied,  the  list printed includes all builtins, with an indica-
	      tion of whether or not each is enabled.  If -s is supplied,  the
	      output  is restricted to the POSIX special builtins.  The return
	      value is 0 unless a name is not a shell builtin or there	is  an
	      error loading a new builtin from a shared object.

       eval [arg ...]
	      The  args	 are read and concatenated together into a single com-
	      mand.  This command is then read and executed by the shell,  and
	      its  exit status is returned as the value of eval.  If there are
	      no args, or only null arguments, eval returns 0.

       exec [-cl] [-a name] [command [arguments]]
	      If command is specified, it replaces the shell.  No new  process
	      is  created.  The arguments become the arguments to command.  If
	      the -l option is supplied, the shell places a dash at the begin-
	      ning  of	the  zeroth  argument passed to command.  This is what
	      login(1) does.  The -c option causes command to be executed with
	      an  empty environment.  If -a is supplied, the shell passes name
	      as the zeroth argument to the executed command.  If command can-
	      not  be executed for some reason, a non-interactive shell exits,
	      unless the shell option execfail is enabled, in  which  case  it
	      returns  failure.	  An  interactive shell returns failure if the
	      file cannot be executed.	If command is not specified, any redi-
	      rections take effect in the current shell, and the return status
	      is 0.  If there is a redirection error, the return status is  1.

       exit [n]
	      Cause  the  shell	 to exit with a status of n.  If n is omitted,
	      the exit status is that of the last command executed.  A trap on
	      EXIT is executed before the shell terminates.

       export [-fn] [name[=word]] ...
       export -p
	      The  supplied names are marked for automatic export to the envi-
	      ronment of subsequently executed commands.  If the -f option  is
	      given,  the names refer to functions.  If no names are given, or
	      if the -p option is supplied, a  list  of	 all  names  that  are
	      exported	in  this  shell	 is printed.  The -n option causes the
	      export property to be removed from each  name.   If  a  variable
	      name  is	followed by =word, the value of the variable is set to
	      word.  export returns an exit status  of	0  unless  an  invalid
	      option  is  encountered,	one  of the names is not a valid shell
	      variable name, or -f is supplied with a name that is not a func-
	      tion.

       fc [-e ename] [-lnr] [first] [last]
       fc -s [pat=rep] [cmd]
	      Fix  Command.  In the first form, a range of commands from first
	      to last is selected from the history list.  First and  last  may
	      be  specified  as a string (to locate the last command beginning
	      with that string) or as a number	(an  index  into  the  history
	      list, where a negative number is used as an offset from the cur-
	      rent command number).  If last is not specified it is set to the
	      current  command	for  listing (so that ''fc -l -10'' prints the
	      last 10 commands) and to first otherwise.	 If first is not spec-
	      ified  it is set to the previous command for editing and -16 for
	      listing.

	      The -n option suppresses the command numbers when listing.   The
	      -r  option reverses the order of the commands.  If the -l option
	      is given, the commands are listed on  standard  output.	Other-
	      wise,  the editor given by ename is invoked on a file containing
	      those commands.  If ename is not given, the value of the	FCEDIT
	      variable	is used, and the value of EDITOR if FCEDIT is not set.
	      If neither variable is set, is used.  When editing is  complete,
	      the edited commands are echoed and executed.

	      In  the  second form, command is re-executed after each instance
	      of pat is replaced by rep.  A useful alias to use with  this  is
	      ''r="fc  -s"'',  so  that	 typing ''r cc'' runs the last command
	      beginning with ''cc'' and typing ''r'' re-executes the last com-
	      mand.

	      If  the  first  form  is	used,  the return value is 0 unless an
	      invalid option is encountered or first or last  specify  history
	      lines  out  of  range.  If the -e option is supplied, the return
	      value is the value of the last command executed or failure if an
	      error occurs with the temporary file of commands.	 If the second
	      form is used, the return status is that of the  command  re-exe-
	      cuted,  unless  cmd  does	 not  specify a valid history line, in
	      which case fc returns failure.

       fg [jobspec]
	      Resume jobspec in the foreground, and make it the	 current  job.
	      If jobspec is not present, the shell's notion of the current job
	      is used.	The return value is that of the	 command  placed  into
	      the  foreground,	or failure if run when job control is disabled
	      or, when run with job control enabled, if jobspec does not spec-
	      ify  a  valid  job  or  jobspec specifies a job that was started
	      without job control.

       getopts optstring name [args]
	      getopts is used by shell procedures to parse positional  parame-
	      ters.   optstring	 contains  the	option characters to be recog-
	      nized; if a character is followed by  a  colon,  the  option  is
	      expected	to have an argument, which should be separated from it
	      by white space.  The colon and question mark characters may  not
	      be  used as option characters.  Each time it is invoked, getopts
	      places the next option in the shell variable name,  initializing
	      name if it does not exist, and the index of the next argument to
	      be processed into the variable OPTIND.  OPTIND is initialized to
	      1	 each  time  the  shell or a shell script is invoked.  When an
	      option requires an argument, getopts places that	argument  into
	      the  variable OPTARG.  The shell does not reset OPTIND automati-
	      cally; it must be	 manually  reset  between  multiple  calls  to
	      getopts within the same shell invocation if a new set of parame-
	      ters is to be used.

	      When the end of options is encountered,  getopts	exits  with  a
	      return  value  greater than zero.	 OPTIND is set to the index of
	      the first non-option argument, and name is set to ?.

	      getopts normally parses the positional parameters, but  if  more
	      arguments are given in args, getopts parses those instead.

	      getopts  can  report errors in two ways.	If the first character
	      of optstring is a colon, silent error  reporting	is  used.   In
	      normal  operation	 diagnostic  messages are printed when invalid
	      options or missing option arguments  are	encountered.   If  the
	      variable	OPTERR	is  set	 to  0, no error messages will be dis-
	      played, even if the first character of optstring is not a colon.

	      If an invalid option is seen, getopts places ? into name and, if
	      not silent, prints an  error  message  and  unsets  OPTARG.   If
	      getopts  is  silent,  the	 option	 character  found is placed in
	      OPTARG and no diagnostic message is printed.

	      If a required argument is not found, and getopts is not  silent,
	      a	 question  mark	 (?) is placed in name, OPTARG is unset, and a
	      diagnostic message is printed.  If getopts  is  silent,  then  a
	      colon  (:)  is  placed  in  name and OPTARG is set to the option
	      character found.

	      getopts returns true if an option, specified or unspecified,  is
	      found.  It returns false if the end of options is encountered or
	      an error occurs.

       hash [-lr] [-p filename] [-dt] [name]
	      For each name, the full file name of the command	is  determined
	      by searching the directories in $PATH and remembered.  If the -p
	      option is supplied, no path search is performed, and filename is
	      used as the full file name of the command.  The -r option causes
	      the shell to forget all remembered  locations.   The  -d	option
	      causes the shell to forget the remembered location of each name.
	      If the -t option is supplied, the full pathname  to  which  each
	      name  corresponds	 is  printed.	If multiple name arguments are
	      supplied with -t, the name is printed  before  the  hashed  full
	      pathname.	 The -l option causes output to be displayed in a for-
	      mat that may be reused as input.	If no arguments are given,  or
	      if only -l is supplied, information about remembered commands is
	      printed.	The return status is true unless a name is  not	 found
	      or an invalid option is supplied.

       help [-dms] [pattern]
	      Display  helpful information about builtin commands.  If pattern
	      is specified, help gives detailed help on all commands  matching
	      pattern;	otherwise  help for all the builtins and shell control
	      structures is printed.
	      -d     Display a short description of each pattern
	      -m     Display the description of each pattern in a manpage-like
		     format
	      -s     Display only a short usage synopsis for each pattern
       The return status is 0 unless no command matches pattern.

       history [n]
       history -c
       history -d offset
       history -anrw [filename]
       history -p arg [arg ...]
       history -s arg [arg ...]
	      With no options, display the command history list with line num-
	      bers.  Lines listed with a * have been modified.	An argument of
	      n	 lists only the last n lines.  If the shell variable HISTTIME-
	      FORMAT is set and not null, it is used as a  format  string  for
	      strftime(3)  to display the time stamp associated with each dis-
	      played history entry.  No intervening blank is  printed  between
	      the  formatted  time stamp and the history line.	If filename is
	      supplied, it is used as the name of the history  file;  if  not,
	      the  value  of HISTFILE is used.	Options, if supplied, have the
	      following meanings:
	      -c     Clear the history list by deleting all the entries.
	      -d offset
		     Delete the history entry at position offset.
	      -a     Append the ''new'' history lines (history	lines  entered
		     since  the	 beginning of the current bash session) to the
		     history file.
	      -n     Read the history lines not already read from the  history
		     file  into	 the  current  history	list.  These are lines
		     appended to the history file since the beginning  of  the
		     current bash session.
	      -r     Read the contents of the history file and use them as the
		     current history.
	      -w     Write the current history to the history file,  overwrit-
		     ing the history file's contents.
	      -p     Perform  history  substitution  on the following args and
		     display the result on  the	 standard  output.   Does  not
		     store  the results in the history list.  Each arg must be
		     quoted to disable normal history expansion.
	      -s     Store the args in the history list	 as  a	single	entry.
		     The  last	command	 in the history list is removed before
		     the args are added.

	      If the HISTTIMEFORMAT variable is set, the time  stamp  informa-
	      tion  associated	with each history entry is written to the his-
	      tory file, marked with the history comment character.  When  the
	      history  file  is read, lines beginning with the history comment
	      character followed immediately by a  digit  are  interpreted  as
	      timestamps for the previous history line.	 The return value is 0
	      unless an invalid option is encountered, an error	 occurs	 while
	      reading  or  writing the history file, an invalid offset is sup-
	      plied as an argument to -d, or the history expansion supplied as
	      an argument to -p fails.

       jobs [-lnprs] [ jobspec ... ]
       jobs -x command [ args ... ]
	      The first form lists the active jobs.  The options have the fol-
	      lowing meanings:
	      -l     List process IDs in addition to the normal information.
	      -p     List only the process  ID	of  the	 job's	process	 group
		     leader.
	      -n     Display  information  only	 about	jobs that have changed
		     status since the user was last notified of their  status.
	      -r     Restrict output to running jobs.
	      -s     Restrict output to stopped jobs.

	      If  jobspec  is given, output is restricted to information about
	      that job.	 The return status is 0 unless an  invalid  option  is
	      encountered or an invalid jobspec is supplied.

	      If the -x option is supplied, jobs replaces any jobspec found in
	      command or args with the corresponding  process  group  ID,  and
	      executes command passing it args, returning its exit status.

       kill [-s sigspec | -n signum | -sigspec] [pid | jobspec] ...
       kill -l [sigspec | exit_status]
	      Send  the	 signal	 named	by  sigspec or signum to the processes
	      named by pid or jobspec.	sigspec is either  a  case-insensitive
	      signal  name such as SIGKILL (with or without the SIG prefix) or
	      a signal number; signum is a signal number.  If sigspec  is  not
	      present,	then  SIGTERM is assumed.  An argument of -l lists the
	      signal names.  If any arguments are supplied when -l  is	given,
	      the  names  of  the  signals  corresponding to the arguments are
	      listed, and the return status is 0.  The exit_status argument to
	      -l  is  a	 number	 specifying either a signal number or the exit
	      status of a process terminated by a signal.  kill	 returns  true
	      if  at  least  one  signal was successfully sent, or false if an
	      error occurs or an invalid option is encountered.

       let arg [arg ...]
	      Each arg is an arithmetic expression to be evaluated (see ARITH-
	      METIC  EVALUATION	 above).   If the last arg evaluates to 0, let
	      returns 1; 0 is returned otherwise.

       local [option] [name[=value] ...]
	      For each argument, a local variable named name is	 created,  and
	      assigned	value.	 The option can be any of the options accepted
	      by declare.  When local is used within a function, it causes the
	      variable	name  to have a visible scope restricted to that func-
	      tion and its children.  With no operands, local writes a list of
	      local  variables	to the standard output.	 It is an error to use
	      local when not within a function.	 The return status is 0 unless
	      local  is	 used outside a function, an invalid name is supplied,
	      or name is a readonly variable.

       logout Exit a login shell.

       mapfile [-n count] [-O origin] [-s count] [-t] [-u  fd]	[-C  callback]
       [-c quantum] [array]
       readarray [-n count] [-O origin] [-s count] [-t] [-u fd] [-C  callback]
       [-c quantum] [array]
	      Read lines from the standard input into the indexed array	 vari-
	      able  array, or from file descriptor fd if the -u option is sup-
	      plied.  The variable MAPFILE is the default array.  Options,  if
	      supplied, have the following meanings:
	      -n     Copy  at  most count lines.  If count is 0, all lines are
		     copied.
	      -O     Begin assigning to array at index	origin.	  The  default
		     index is 0.
	      -s     Discard the first count lines read.
	      -t     Remove a trailing newline from each line read.
	      -u     Read  lines  from file descriptor fd instead of the stan-
		     dard input.
	      -C     Evaluate callback each time quantum lines are read.   The
		     -c option specifies quantum.
	      -c     Specify  the  number  of  lines read between each call to
		     callback.

	      If -C is specified without -c,  the  default  quantum  is	 5000.
	      When callback is evaluated, it is supplied the index of the next
	      array element to be assigned as an additional  argument.	 call-
	      back  is	evaluated  after the line is read but before the array
	      element is assigned.

	      If not supplied with an  explicit	 origin,  mapfile  will	 clear
	      array before assigning to it.

	      mapfile  returns successfully unless an invalid option or option
	      argument is supplied, array is invalid or	 unassignable,	or  if
	      array is not an indexed array.

       popd [-n] [+n] [-n]
	      Removes  entries	from  the directory stack.  With no arguments,
	      removes the top directory from the stack, and performs a	cd  to
	      the new top directory.  Arguments, if supplied, have the follow-
	      ing meanings:
	      -n     Suppresses the normal change of directory	when  removing
		     directories  from	the  stack,  so that only the stack is
		     manipulated.
	      +n     Removes the nth entry counting from the left of the  list
		     shown  by	dirs, starting with zero.  For example: ''popd
		     +0'' removes the first directory, ''popd +1'' the second.
	      -n     Removes the nth entry counting from the right of the list
		     shown by dirs, starting with zero.	 For  example:	''popd
		     -0''  removes the last directory, ''popd -1'' the next to
		     last.

	      If the popd command is successful, a dirs is performed as	 well,
	      and  the	return	status is 0.  popd returns false if an invalid
	      option is encountered, the directory stack is empty, a non-exis-
	      tent directory stack entry is specified, or the directory change
	      fails.

       printf [-v var] format [arguments]
	      Write the formatted arguments to the standard output  under  the
	      control  of  the format.	The format is a character string which
	      contains three types of objects:	plain  characters,  which  are
	      simply  copied  to  standard output, character escape sequences,
	      which are converted and copied to the standard output, and  for-
	      mat  specifications,  each  of which causes printing of the next
	      successive argument.  In addition to the standard printf(1) for-
	      mats,  %b	 causes printf to expand backslash escape sequences in
	      the corresponding argument (except that  \c  terminates  output,
	      backslashes in \', \", and \? are not removed, and octal escapes
	      beginning with \0 may contain up to four digits), and %q	causes
	      printf to output the corresponding argument in a format that can
	      be reused as shell input.

	      The -v option causes the output to be assigned to	 the  variable
	      var rather than being printed to the standard output.

	      The  format  is  reused as necessary to consume all of the argu-
	      ments.  If the format requires more arguments than are supplied,
	      the  extra  format  specifications  behave as if a zero value or
	      null string, as appropriate,  had	 been  supplied.   The	return
	      value is zero on success, non-zero on failure.

       pushd [-n] [+n] [-n]
       pushd [-n] [dir]
	      Adds  a  directory to the top of the directory stack, or rotates
	      the stack, making the new top of the stack the  current  working
	      directory.  With no arguments, exchanges the top two directories
	      and returns 0, unless the directory stack is empty.   Arguments,
	      if supplied, have the following meanings:
	      -n     Suppresses	 the  normal  change  of directory when adding
		     directories to the stack,	so  that  only	the  stack  is
		     manipulated.
	      +n     Rotates  the  stack  so  that the nth directory (counting
		     from the left of the list shown by	 dirs,	starting  with
		     zero) is at the top.
	      -n     Rotates  the  stack  so  that the nth directory (counting
		     from the right of the list shown by dirs,	starting  with
		     zero) is at the top.
	      dir    Adds dir to the directory stack at the top, making it the
		     new current working directory.

	      If the pushd command is successful, a dirs is performed as well.
	      If  the first form is used, pushd returns 0 unless the cd to dir
	      fails.  With the second form, pushd returns 0 unless the	direc-
	      tory  stack  is empty, a non-existent directory stack element is
	      specified, or the directory change to the specified new  current
	      directory fails.

       pwd [-LP]
	      Print  the  absolute  pathname of the current working directory.
	      The pathname printed contains no symbolic links if the -P option
	      is supplied or the -o physical option to the set builtin command
	      is enabled.  If the -L option is used, the pathname printed  may
	      contain  symbolic links.	The return status is 0 unless an error
	      occurs while reading the name of the  current  directory	or  an
	      invalid option is supplied.

       read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p
       prompt] [-t timeout] [-u fd] [name ...]
	      One  line	 is  read  from	 the  standard input, or from the file
	      descriptor fd supplied as an argument to the -u option, and  the
	      first word is assigned to the first name, the second word to the
	      second name, and so on, with leftover words and their  interven-
	      ing  separators  assigned	 to the last name.  If there are fewer
	      words read from the input stream than names, the remaining names
	      are  assigned  empty  values.  The characters in IFS are used to
	      split the line into words.  The backslash character (\)  may  be
	      used  to	remove any special meaning for the next character read
	      and for line continuation.  Options, if supplied, have the  fol-
	      lowing meanings:
	      -a aname
		     The words are assigned to sequential indices of the array
		     variable aname, starting at 0.  aname is unset before any
		     new  values  are  assigned.   Other  name	arguments  are
		     ignored.
	      -d delim
		     The first character of delim is  used  to	terminate  the
		     input line, rather than newline.
	      -e     If the standard input is coming from a terminal, readline
		     (see READLINE above) is used to obtain the	 line.	 Read-
		     line  uses	 the  current (or default, if line editing was
		     not previously active) editing settings.
	      -i text
		     If readline is being used	to  read  the  line,  text  is
		     placed into the editing buffer before editing begins.
	      -n nchars
		     read  returns after reading nchars characters rather than
		     waiting for a complete line of input, but honor a	delim-
		     iter  if fewer than nchars characters are read before the
		     delimiter.
	      -N nchars
		     read returns  after  reading  exactly  nchars  characters
		     rather  than waiting for a complete line of input, unless
		     EOF is encountered or read times out.  Delimiter  charac-
		     ters  encountered	in the input are not treated specially
		     and do not cause read to return until  nchars  characters
		     are read.
	      -p prompt
		     Display prompt on standard error, without a trailing new-
		     line, before attempting to read any input.	 The prompt is
		     displayed only if input is coming from a terminal.
	      -r     Backslash does not act as an escape character.  The back-
		     slash is considered to be part of the line.  In  particu-
		     lar,  a  backslash-newline pair may not be used as a line
		     continuation.
	      -s     Silent mode.  If input is coming from a terminal, charac-
		     ters are not echoed.
	      -t timeout
		     Cause  read  to time out and return failure if a complete
		     line of input is not read within timeout seconds.	 time-
		     out  may  be  a  decimal number with a fractional portion
		     following the decimal point.  This option is only	effec-
		     tive  if  read is reading input from a terminal, pipe, or
		     other special file; it has no effect  when	 reading  from
		     regular  files.  If timeout is 0, read returns success if
		     input is available	 on  the  specified  file  descriptor,
		     failure  otherwise.   The exit status is greater than 128
		     if the timeout is exceeded.
	      -u fd  Read input from file descriptor fd.

	      If no names are supplied, the line read is assigned to the vari-
	      able  REPLY.   The  return  code	is zero, unless end-of-file is
	      encountered, read times out (in which case the  return  code  is
	      greater  than 128), or an invalid file descriptor is supplied as
	      the argument to -u.

       readonly [-aApf] [name[=word] ...]
	      The given names are marked readonly; the values of  these	 names
	      may  not	be changed by subsequent assignment.  If the -f option
	      is supplied, the functions corresponding to  the	names  are  so
	      marked.	The  -a	 option	 restricts  the	 variables  to indexed
	      arrays; the -A option restricts  the  variables  to  associative
	      arrays.	If no name arguments are given, or if the -p option is
	      supplied, a list of all  readonly	 names	is  printed.   The  -p
	      option  causes  output  to  be displayed in a format that may be
	      reused as input.	If a variable name is followed by  =word,  the
	      value  of	 the  variable is set to word.	The return status is 0
	      unless an invalid option is encountered, one of the names is not
	      a	 valid shell variable name, or -f is supplied with a name that
	      is not a function.

       return [n]
	      Causes a function to exit with the return value specified by  n.
	      If  n  is omitted, the return status is that of the last command
	      executed in the function body.  If used outside a function,  but
	      during  execution	 of  a	script	by the .  (source) command, it
	      causes the shell to stop executing that script and return either
	      n	 or  the  exit	status of the last command executed within the
	      script as the exit status of the	script.	  If  used  outside  a
	      function	and  not during execution of a script by ., the return
	      status is false.	Any command associated with the RETURN trap is
	      executed	before execution resumes after the function or script.

       set [--abefhkmnptuvxBCEHPT] [-o option] [arg ...]
       set [+abefhkmnptuvxBCEHPT] [+o option] [arg ...]
	      Without options, the name and value of each shell	 variable  are
	      displayed in a format that can be reused as input for setting or
	      resetting the currently-set variables.  Read-only variables can-
	      not  be  reset.  In posix mode, only shell variables are listed.
	      The output is sorted according  to  the  current	locale.	  When
	      options  are specified, they set or unset shell attributes.  Any
	      arguments remaining after option processing are treated as  val-
	      ues for the positional parameters and are assigned, in order, to
	      $1, $2, ...  $n.	Options,  if  specified,  have	the  following
	      meanings:
	      -a      Automatically  mark  variables  and  functions which are
		      modified or created for export  to  the  environment  of
		      subsequent commands.
	      -b      Report  the status of terminated background jobs immedi-
		      ately, rather than before the next primary prompt.  This
		      is effective only when job control is enabled.
	      -e      Exit  immediately	 if a pipeline (which may consist of a
		      single simple command),  a subshell command enclosed  in
		      parentheses,  or one of the commands executed as part of
		      a command list enclosed by  braces  (see	SHELL  GRAMMAR
		      above) exits with a non-zero status.  The shell does not
		      exit if the command that fails is part  of  the  command
		      list  immediately	 following  a  while or until keyword,
		      part of the test	following  the	if  or	elif  reserved
		      words,  part  of any command executed in a && or || list
		      except the command following the final  &&  or  ||,  any
		      command  in a pipeline but the last, or if the command's
		      return value is being inverted with !.  A trap  on  ERR,
		      if set, is executed before the shell exits.  This option
		      applies to the shell environment and each subshell envi-
		      ronment  separately  (see	 COMMAND EXECUTION ENVIRONMENT
		      above), and may cause subshells to exit before executing
		      all the commands in the subshell.
	      -f      Disable pathname expansion.
	      -h      Remember	the location of commands as they are looked up
		      for execution.  This is enabled by default.
	      -k      All arguments in the form of assignment  statements  are
		      placed  in the environment for a command, not just those
		      that precede the command name.
	      -m      Monitor mode.  Job control is enabled.  This  option  is
		      on  by  default  for  interactive shells on systems that
		      support it (see JOB  CONTROL  above).   Background  pro-
		      cesses  run  in a separate process group and a line con-
		      taining their exit status is printed upon their  comple-
		      tion.
	      -n      Read commands but do not execute them.  This may be used
		      to check a shell script  for  syntax  errors.   This  is
		      ignored by interactive shells.
	      -o option-name
		      The option-name can be one of the following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use  an  emacs-style command line editing inter-
			      face.  This is enabled by default when the shell
			      is interactive, unless the shell is started with
			      the --noediting option.  This also  affects  the
			      editing interface used for read -e.
		      errexit Same as -e.
		      errtrace
			      Same as -E.
		      functrace
			      Same as -T.
		      hashall Same as -h.
		      histexpand
			      Same as -H.
		      history Enable command history, as described above under
			      HISTORY.	This option is on by default in inter-
			      active shells.
		      ignoreeof
			      The   effect   is	  as   if  the	shell  command
			      ''IGNOREEOF=10'' had been	 executed  (see	 Shell
			      Variables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.
		      nolog   Currently ignored.
		      notify  Same as -b.
		      nounset Same as -u.
		      onecmd  Same as -t.
		      physical
			      Same as -P.
		      pipefail
			      If  set,	the  return value of a pipeline is the
			      value of the last (rightmost)  command  to  exit
			      with  a non-zero status, or zero if all commands
			      in the pipeline exit successfully.  This	option
			      is disabled by default.
		      posix   Change  the  behavior  of bash where the default
			      operation differs from  the  POSIX  standard  to
			      match the standard (posix mode).
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      vi      Use  a  vi-style command line editing interface.
			      This also affects the editing interface used for
			      read -e.
		      xtrace  Same as -x.
		      If -o is supplied with no option-name, the values of the
		      current options are printed.  If +o is supplied with  no
		      option-name,  a  series  of set commands to recreate the
		      current option settings is  displayed  on	 the  standard
		      output.
	      -p      Turn  on	privileged  mode.   In this mode, the $ENV and
		      $BASH_ENV files are not processed, shell	functions  are
		      not  inherited  from the environment, and the SHELLOPTS,
		      BASHOPTS, CDPATH,	 and  GLOBIGNORE  variables,  if  they
		      appear in the environment, are ignored.  If the shell is
		      started with the effective user (group) id not equal  to
		      the  real user (group) id, and the -p option is not sup-
		      plied, these actions are taken and the effective user id
		      is  set  to  the real user id.  If the -p option is sup-
		      plied at startup, the effective user id  is  not	reset.
		      Turning  this  option  off causes the effective user and
		      group ids to be set to the real user and group ids.
	      -t      Exit after reading and executing one command.
	      -u      Treat unset variables and parameters other than the spe-
		      cial  parameters "@" and "*" as an error when performing
		      parameter expansion.  If expansion is  attempted	on  an
		      unset  variable  or parameter, the shell prints an error
		      message, and, if not interactive, exits with a  non-zero
		      status.
	      -v      Print shell input lines as they are read.
	      -x      After  expanding	each simple command, for command, case
		      command, select command, or arithmetic for command, dis-
		      play  the expanded value of PS4, followed by the command
		      and its expanded arguments or associated word list.
	      -B      The shell performs brace expansion (see Brace  Expansion
		      above).  This is on by default.
	      -C      If  set,	bash  does not overwrite an existing file with
		      the >, >&, and <> redirection operators.	 This  may  be
		      overridden when creating output files by using the redi-
		      rection operator >| instead of >.
	      -E      If set, any trap on ERR is inherited by shell functions,
		      command  substitutions,  and commands executed in a sub-
		      shell environment.  The ERR trap is normally not	inher-
		      ited in such cases.
	      -H      Enable !	style history substitution.  This option is on
		      by default when the shell is interactive.
	      -P      If set, the shell does not follow	 symbolic  links  when
		      executing	 commands  such	 as cd that change the current
		      working  directory.   It	uses  the  physical  directory
		      structure instead.  By default, bash follows the logical
		      chain of	directories  when  performing  commands	 which
		      change the current directory.
	      -T      If  set,	any traps on DEBUG and RETURN are inherited by
		      shell functions,	command	 substitutions,	 and  commands
		      executed	in  a  subshell	 environment.	The  DEBUG and
		      RETURN traps are normally not inherited in such cases.
	      --      If no arguments follow this option, then the  positional
		      parameters are unset.  Otherwise, the positional parame-
		      ters are set to the args, even if	 some  of  them	 begin
		      with a -.
	      -	      Signal  the  end of options, cause all remaining args to
		      be assigned to the positional parameters.	 The -x and -v
		      options are turned off.  If there are no args, the posi-
		      tional parameters remain unchanged.

	      The options are off by default unless otherwise noted.  Using  +
	      rather  than  -  causes  these  options  to  be turned off.  The
	      options can also be specified as arguments to an	invocation  of
	      the  shell.  The current set of options may be found in $-.  The
	      return status is always true unless an invalid option is encoun-
	      tered.

       shift [n]
	      The  positional  parameters  from n+1 ... are renamed to $1 ....
	      Parameters represented by the numbers  $#	 down  to  $#-n+1  are
	      unset.   n  must	be a non-negative number less than or equal to
	      $#.  If n is 0, no parameters are changed.  If n is  not	given,
	      it  is assumed to be 1.  If n is greater than $#, the positional
	      parameters are not changed.  The return status is	 greater  than
	      zero if n is greater than $# or less than zero; otherwise 0.

       shopt [-pqsu] [-o] [optname ...]
	      Toggle the values of variables controlling optional shell behav-
	      ior.  With no options, or with the -p option, a list of all set-
	      table options is displayed, with an indication of whether or not
	      each is set.  The -p option causes output to be displayed	 in  a
	      form  that  may be reused as input.  Other options have the fol-
	      lowing meanings:
	      -s     Enable (set) each optname.
	      -u     Disable (unset) each optname.
	      -q     Suppresses normal output (quiet mode); the return	status
		     indicates whether the optname is set or unset.  If multi-
		     ple optname arguments are given with -q, the return  sta-
		     tus  is zero if all optnames are enabled; non-zero other-
		     wise.
	      -o     Restricts the values of optname to be those  defined  for
		     the -o option to the set builtin.

	      If  either  -s or -u is used with no optname arguments, the dis-
	      play is limited to those options which are set or unset, respec-
	      tively.	Unless otherwise noted, the shopt options are disabled
	      (unset) by default.

	      The return status when listing options is zero if	 all  optnames
	      are  enabled,  non-zero  otherwise.   When  setting or unsetting
	      options, the return status is zero unless an optname  is	not  a
	      valid shell option.

	      The list of shopt options is:

	      autocd  If  set,	a command name that is the name of a directory
		      is executed as if it were the argument to	 the  cd  com-
		      mand.  This option is only used by interactive shells.
	      cdable_vars
		      If  set,	an  argument to the cd builtin command that is
		      not a directory is assumed to be the name of a  variable
		      whose value is the directory to change to.
	      cdspell If set, minor errors in the spelling of a directory com-
		      ponent in a cd command will be  corrected.   The	errors
		      checked for are transposed characters, a missing charac-
		      ter, and one character too many.	 If  a	correction  is
		      found,  the corrected file name is printed, and the com-
		      mand proceeds.  This option is only used by  interactive
		      shells.
	      checkhash
		      If set, bash checks that a command found in the hash ta-
		      ble exists before trying to execute  it.	 If  a	hashed
		      command  no  longer exists, a normal path search is per-
		      formed.
	      checkjobs
		      If set, bash lists the status of any stopped and running
		      jobs  before  exiting an interactive shell.  If any jobs
		      are running, this causes the exit to be deferred until a
		      second  exit is attempted without an intervening command
		      (see JOB CONTROL above).	 The  shell  always  postpones
		      exiting if any jobs are stopped.
	      checkwinsize
		      If  set,	bash checks the window size after each command
		      and, if necessary,  updates  the	values	of  LINES  and
		      COLUMNS.
	      cmdhist If  set,	bash attempts to save all lines of a multiple-
		      line command in the same	history	 entry.	  This	allows
		      easy re-editing of multi-line commands.
	      compat31
		      If set, bash changes its behavior to that of version 3.1
		      with respect to quoted arguments to the conditional com-
		      mand's =~ operator.
	      compat32
		      If set, bash changes its behavior to that of version 3.2
		      with respect to locale-specific string  comparison  when
		      using the conditional command's < and > operators.
	      compat40
		      If set, bash changes its behavior to that of version 4.0
		      with respect to locale-specific string  comparison  when
		      using  the  conditional  command's < and > operators and
		      the effect of interrupting a command list.
	      dirspell
		      If set, bash attempts spelling correction	 on  directory
		      names  during word completion if the directory name ini-
		      tially supplied does not exist.
	      dotglob If set, bash includes filenames beginning with a '.'  in
		      the results of pathname expansion.
	      execfail
		      If set, a non-interactive shell will not exit if it can-
		      not execute the file specified as	 an  argument  to  the
		      exec  builtin  command.	An  interactive shell does not
		      exit if exec fails.
	      expand_aliases
		      If set, aliases are expanded as  described  above	 under
		      ALIASES.	This option is enabled by default for interac-
		      tive shells.
	      extdebug
		      If set,  behavior	 intended  for	use  by	 debuggers  is
		      enabled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name supplied as an argument.
		      2.     If	 the  command  run by the DEBUG trap returns a
			     non-zero value, the next command is  skipped  and
			     not executed.
		      3.     If	 the  command  run by the DEBUG trap returns a
			     value of 2, and the shell is executing in a  sub-
			     routine  (a shell function or a shell script exe-
			     cuted by the . or source  builtins),  a  call  to
			     return is simulated.
		      4.     BASH_ARGC	and BASH_ARGV are updated as described
			     in their descriptions above.
		      5.     Function tracing is enabled:   command  substitu-
			     tion, shell functions, and subshells invoked with
			     ( command ) inherit the DEBUG and RETURN traps.
		      6.     Error tracing is enabled:	command	 substitution,
			     shell  functions,	and  subshells	invoked with (
			     command ) inherit the ERROR trap.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      extquote
		      If  set,	$'string'  and	$"string" quoting is performed
		      within  ${parameter}  expansions	enclosed   in	double
		      quotes.  This option is enabled by default.
	      failglob
		      If  set,	patterns  which fail to match filenames during
		      pathname expansion result in an expansion error.
	      force_fignore
		      If set, the suffixes  specified  by  the	FIGNORE	 shell
		      variable	cause words to be ignored when performing word
		      completion even if the ignored words are the only possi-
		      ble  completions.	  See  SHELL  VARIABLES	 above	for  a
		      description of  FIGNORE.	 This  option  is  enabled  by
		      default.
	      globstar
		      If set, the pattern ** used in a pathname expansion con-
		      text will match a files and zero or more directories and
		      subdirectories.  If the pattern is followed by a /, only
		      directories and subdirectories match.
	      gnu_errfmt
		      If set, shell error messages are written in the standard
		      GNU error message format.
	      histappend
		      If  set,	the history list is appended to the file named
		      by the value of the HISTFILE  variable  when  the	 shell
		      exits, rather than overwriting the file.
	      histreedit
		      If  set, and readline is being used, a user is given the
		      opportunity to re-edit a failed history substitution.
	      histverify
		      If set, and readline is being used, the results of  his-
		      tory  substitution  are  not  immediately	 passed to the
		      shell parser.  Instead, the  resulting  line  is	loaded
		      into the readline editing buffer, allowing further modi-
		      fication.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to
		      perform  hostname	 completion when a word containing a @
		      is  being	 completed  (see  Completing  under   READLINE
		      above).  This is enabled by default.
	      huponexit
		      If set, bash will send SIGHUP to all jobs when an inter-
		      active login shell exits.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word
		      and  all remaining characters on that line to be ignored
		      in an interactive	 shell	(see  COMMENTS	above).	  This
		      option is enabled by default.
	      lithist If  set,	and  the cmdhist option is enabled, multi-line
		      commands are saved to the history with embedded newlines
		      rather than using semicolon separators where possible.
	      login_shell
		      The  shell  sets this option if it is started as a login
		      shell (see INVOCATION above).   The  value  may  not  be
		      changed.
	      mailwarn
		      If  set,	and  a file that bash is checking for mail has
		      been accessed since the last time it  was	 checked,  the
		      message  ''The  mail in mailfile has been read'' is dis-
		      played.
	      no_empty_cmd_completion
		      If set, and  readline  is	 being	used,  bash  will  not
		      attempt to search the PATH for possible completions when
		      completion is attempted on an empty line.
	      nocaseglob
		      If set, bash matches  filenames  in  a  case-insensitive
		      fashion when performing pathname expansion (see Pathname
		      Expansion above).
	      nocasematch
		      If set, bash  matches  patterns  in  a  case-insensitive
		      fashion when performing matching while executing case or
		      [[ conditional commands.
	      nullglob
		      If set, bash allows patterns which match no  files  (see
		      Pathname	Expansion  above)  to expand to a null string,
		      rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Pro-
		      grammable Completion above) are enabled.	This option is
		      enabled by default.
	      promptvars
		      If set, prompt strings undergo parameter expansion, com-
		      mand   substitution,  arithmetic	expansion,  and	 quote
		      removal after being expanded as described	 in  PROMPTING
		      above.  This option is enabled by default.
	      restricted_shell
		      The   shell  sets	 this  option  if  it  is  started  in
		      restricted mode (see RESTRICTED SHELL below).  The value
		      may  not be changed.  This is not reset when the startup
		      files are executed, allowing the startup files  to  dis-
		      cover whether or not a shell is restricted.
	      shift_verbose
		      If  set,	the shift builtin prints an error message when
		      the shift count exceeds the number of positional parame-
		      ters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to
		      find the directory containing the file  supplied	as  an
		      argument.	 This option is enabled by default.
	      xpg_echo
		      If   set,	 the  echo  builtin  expands  backslash-escape
		      sequences by default.
       suspend [-f]
	      Suspend the execution of this shell until it receives a  SIGCONT
	      signal. When the suspended shell is a background process, it can
	      be restarted by the fg command. For more information,  read  the
	      JOB  CONTROL  section.  The  suspend command can not suspend the
	      login shell. However, when -f option is specified, suspend  com-
	      mand  can	 suspend  even	login  shell.	The return status is 0
	      unless the shell is a login shell and -f is not supplied, or  if
	      job control is not enabled.
       test expr
       [ expr ]
	      Return  a	 status	 of  0 or 1 depending on the evaluation of the
	      conditional expression expr.  Each operator and operand must  be
	      a	 separate argument.  Expressions are composed of the primaries
	      described above under CONDITIONAL EXPRESSIONS.   test  does  not
	      accept any options, nor does it accept and ignore an argument of
	      -- as signifying the end of options.

	      Expressions may  be  combined  using  the	 following  operators,
	      listed  in  decreasing  order  of	 precedence.   The  evaluation
	      depends on the number of arguments; see below.
	      ! expr True if expr is false.
	      ( expr )
		     Returns the value of expr.	 This may be used to  override
		     the normal precedence of operators.
	      expr1 -a expr2
		     True if both expr1 and expr2 are true.
	      expr1 -o expr2
		     True if either expr1 or expr2 is true.

	      test and [ evaluate conditional expressions using a set of rules
	      based on the number of arguments.

	      0 arguments
		     The expression is false.
	      1 argument
		     The expression is true if and only if the argument is not
		     null.
	      2 arguments
		     If the first argument is !, the expression is true if and
		     only if the second argument is null.  If the first	 argu-
		     ment  is  one  of	the unary conditional operators listed
		     above under CONDITIONAL EXPRESSIONS,  the	expression  is
		     true if the unary test is true.  If the first argument is
		     not a valid unary conditional operator, the expression is
		     false.
	      3 arguments
		     If	 the  second argument is one of the binary conditional
		     operators listed above under CONDITIONAL EXPRESSIONS, the
		     result of the expression is the result of the binary test
		     using the first and third arguments as operands.  The  -a
		     and  -o  operators	 are  considered binary operators when
		     there are three arguments.	 If the first argument	is  !,
		     the  value is the negation of the two-argument test using
		     the second and third arguments.  If the first argument is
		     exactly ( and the third argument is exactly ), the result
		     is the one-argument test of the second argument.	Other-
		     wise, the expression is false.
	      4 arguments
		     If the first argument is !, the result is the negation of
		     the three-argument expression composed of	the  remaining
		     arguments.	 Otherwise, the expression is parsed and eval-
		     uated according to	 precedence  using  the	 rules	listed
		     above.
	      5 or more arguments
		     The  expression  is  parsed  and  evaluated  according to
		     precedence using the rules listed above.

       times  Print the accumulated user and system times for  the  shell  and
	      for processes run from the shell.	 The return status is 0.

       trap [-lp] [[arg] sigspec ...]
	      The  command  arg	 is  to	 be  read  and executed when the shell
	      receives signal(s) sigspec.  If arg is absent (and  there	 is  a
	      single  sigspec)	or  -,	each  specified signal is reset to its
	      original disposition (the value it  had  upon  entrance  to  the
	      shell).	If arg is the null string the signal specified by each
	      sigspec is ignored by the shell and by the commands it  invokes.
	      If  arg  is  not present and -p has been supplied, then the trap
	      commands associated with each  sigspec  are  displayed.	If  no
	      arguments	 are  supplied or if only -p is given, trap prints the
	      list of commands associated with each  signal.   The  -l	option
	      causes  the shell to print a list of signal names and their cor-
	      responding numbers.   Each  sigspec  is  either  a  signal  name
	      defined  in  <signal.h>,	or  a signal number.  Signal names are
	      case insensitive and the SIG prefix is optional.

	      If a sigspec is EXIT (0) the command arg	is  executed  on  exit
	      from  the shell.	If a sigspec is DEBUG, the command arg is exe-
	      cuted before every simple command, for  command,	case  command,
	      select  command,	every  arithmetic  for command, and before the
	      first command executes in a shell function  (see	SHELL  GRAMMAR
	      above).	Refer to the description of the extdebug option to the
	      shopt builtin for details of its effect on the DEBUG trap.  If a
	      sigspec is RETURN, the command arg is executed each time a shell
	      function or a script executed with the . or source builtins fin-
	      ishes executing.

	      If a sigspec is ERR, the command arg is executed whenever a sim-
	      ple command has a non-zero exit status, subject to the following
	      conditions.   The ERR trap is not executed if the failed command
	      is part of the command list immediately  following  a  while  or
	      until  keyword,  part  of the test in an if statement, part of a
	      command executed in a && or || list, or if the command's	return
	      value  is	 being	inverted via !.	 These are the same conditions
	      obeyed by the errexit option.

	      Signals ignored upon entry to the shell cannot be trapped, reset
	      or listed.  Trapped signals that are not being ignored are reset
	      to their original values in a subshell or	 subshell  environment
	      when  one is created.  The return status is false if any sigspec
	      is invalid; otherwise trap returns true.

       type [-aftpP] name [name ...]
	      With no options, indicate how each name would be interpreted  if
	      used as a command name.  If the -t option is used, type prints a
	      string which is one of alias,  keyword,  function,  builtin,  or
	      file  if	name  is  an  alias,  shell  reserved  word, function,
	      builtin, or disk file, respectively.  If the name is not	found,
	      then  nothing  is	 printed,  and	an  exit  status  of  false is
	      returned.	 If the -p option is used,  type  either  returns  the
	      name of the disk file that would be executed if name were speci-
	      fied as a command name, or nothing if ''type -t name'' would not
	      return  file.  The -P option forces a PATH search for each name,
	      even if ''type -t name'' would not return file.  If a command is
	      hashed,  -p  and	-P print the hashed value, not necessarily the
	      file that appears first in PATH.	If the -a option is used, type
	      prints  all of the places that contain an executable named name.
	      This includes aliases and functions,  if	and  only  if  the  -p
	      option  is  not  also used.  The table of hashed commands is not
	      consulted when using -a.	The -f option suppresses  shell	 func-
	      tion  lookup, as with the command builtin.  type returns true if
	      all of the arguments are found, false if any are not found.

       ulimit [-HSTabcdefilmnpqrstuvx [limit]]
	      Provides control over the resources available to the  shell  and
	      to  processes started by it, on systems that allow such control.
	      The -H and -S options specify that the hard or soft limit is set
	      for  the	given resource.	 A hard limit cannot be increased by a
	      non-root user once it is set; a soft limit may be	 increased  up
	      to  the value of the hard limit.	If neither -H nor -S is speci-
	      fied, both the soft and hard limits are set.  The value of limit
	      can be a number in the unit specified for the resource or one of
	      the special values hard, soft, or unlimited, which stand for the
	      current  hard  limit,  the  current  soft	 limit,	 and no limit,
	      respectively.  If limit is omitted, the  current	value  of  the
	      soft  limit  of the resource is printed, unless the -H option is
	      given.  When more than one resource is specified, the limit name
	      and unit are printed before the value.  Other options are inter-
	      preted as follows:
	      -a     All current limits are reported
	      -b     The maximum socket buffer size
	      -c     The maximum size of core files created
	      -d     The maximum size of a process's data segment
	      -e     The maximum scheduling priority ("nice")
	      -f     The maximum size of files written by the  shell  and  its
		     children
	      -i     The maximum number of pending signals
	      -l     The maximum size that may be locked into memory
	      -m     The  maximum resident set size (many systems do not honor
		     this limit)
	      -n     The maximum number of open file descriptors (most systems
		     do not allow this value to be set)
	      -p     The pipe size in 512-byte blocks (this may not be set)
	      -q     The maximum number of bytes in POSIX message queues
	      -r     The maximum real-time scheduling priority
	      -s     The maximum stack size
	      -t     The maximum amount of cpu time in seconds
	      -u     The  maximum  number  of  processes available to a single
		     user
	      -v     The maximum amount of virtual  memory  available  to  the
		     shell
	      -x     The maximum number of file locks
	      -T     The maximum number of threads

	      If limit is given, it is the new value of the specified resource
	      (the -a option is display only).	If no option is given, then -f
	      is  assumed.  Values are in 1024-byte increments, except for -t,
	      which is in seconds, -p, which is in units of  512-byte  blocks,
	      and  -T,	-b, -n, and -u, which are unscaled values.  The return
	      status is 0 unless an invalid option or argument is supplied, or
	      an  error	 occurs	 while	setting	 a  new	 limit.	 In POSIX Mode
	      512-byte blocks are used for the '-c' and '-f' options.

       umask [-p] [-S] [mode]
	      The user file-creation mask is set to mode.  If mode begins with
	      a	 digit,	 it is interpreted as an octal number; otherwise it is
	      interpreted as a symbolic mode mask similar to that accepted  by
	      chmod(1).	  If mode is omitted, the current value of the mask is
	      printed.	The -S option causes the mask to be  printed  in  sym-
	      bolic  form;  the	 default output is an octal number.  If the -p
	      option is supplied, and mode is omitted, the output is in a form
	      that may be reused as input.  The return status is 0 if the mode
	      was successfully changed or if no mode  argument	was  supplied,
	      and false otherwise.

       unalias [-a] [name ...]
	      Remove  each  name  from	the list of defined aliases.  If -a is
	      supplied, all alias definitions are removed.  The	 return	 value
	      is true unless a supplied name is not a defined alias.

       unset [-fv] [name ...]
	      For  each	 name,	remove the corresponding variable or function.
	      If no options are supplied, or the -v option is given, each name
	      refers  to  a  shell  variable.	Read-only variables may not be
	      unset.  If -f is specified, each name refers to  a  shell	 func-
	      tion,  and the function definition is removed.  Each unset vari-
	      able or function is removed from the environment passed to  sub-
	      sequent  commands.   If any of COMP_WORDBREAKS, RANDOM, SECONDS,
	      LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are  unset,  they
	      lose  their  special  properties,	 even if they are subsequently
	      reset.  The exit status is true unless a name is readonly.

       wait [n ...]
	      Wait for each specified process and return its termination  sta-
	      tus.   Each  n  may be a process ID or a job specification; if a
	      job spec is given, all processes	in  that  job's	 pipeline  are
	      waited  for.  If n is not given, all currently active child pro-
	      cesses are waited for, and the return  status  is	 zero.	 If  n
	      specifies	 a  non-existent  process or job, the return status is
	      127.  Otherwise, the return status is the	 exit  status  of  the
	      last process or job waited for.

SEE ALSO
       bash(1), sh(1)

GNU Bash-4.0			  2004 Apr 20		      BASH_BUILTINS(1)							
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