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BASH_BUILTINS(1)	    General Commands Manual	      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 [-e]]] [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.  If the -e option is supplied with -P,  and  the  current
	      working directory cannot be successfully determined after a suc-
	      cessful directory change, cd will return an unsuccessful status.
	      An  argument  of	-  is  equivalent  to $OLDPWD.	If a non-empty
	      directory name from CDPATH is used, or if - is the  first	 argu-
	      ment, and the directory change is successful, the absolute path-
	      name 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 program-
	      mable completion code had generated them directly from a comple-
	      tion  specification  with the same flags.	 If word is specified,
	      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  Program-
	      mable 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.
	      -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.
	      -G globpat
		      The pathname expansion pattern globpat  is  expanded  to
		      generate the possible completions.
	      -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.
	      -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.
	      -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.

	      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-executing 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
	      completion 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 [-aAfFgilrtux] [-p] [name[=value] ...]
       typeset [-aAfFgilrtux] [-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 -g option forces
	      variables	 to  be	 created or modified at the global scope, even
	      when declare is executed in a shell function.  It is ignored  in
	      all  other cases.	 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,
	      unless the -g option is supplied, If a variable name is followed
	      by  =value,  the	value  of  the	variable 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 readonly variable, an  attempt
	      is  made	to  turn off array status for an array variable, or an
	      attempt is made to display a non-existent function with -f.

       dirs [+n] [-n] [-clpv]
	      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
	      \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)
	      \uHHHH the  Unicode (ISO/IEC 10646) character whose value is the
		     hexadecimal value HHHH (one to four hex digits)
	      \UHHHHHHHH
		     the Unicode (ISO/IEC 10646) character whose value is  the
		     hexadecimal value HHHHHHHH (one to eight 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]
	      Each time hash is invoked, the full pathname of the command name
	      is  determined  by searching the directories in $PATH and remem-
	      bered.  Any previously-remembered pathname is discarded.	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	 argu-
	      ments  are  supplied  with  -t,  the  name is printed before the
	      hashed full pathname.  The -l option causes output  to  be  dis-
	      played in a format that may be reused as input.  If no arguments
	      are given, or if only -l is supplied, information	 about	remem-
	      bered  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.
	      -n     Display  information  only	 about	jobs that have changed
		     status since the user was last notified of their status.
	      -p     List only the process  ID	of  the	 job's	process	 group
		     leader.
	      -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 and the line to be assigned to that
	      element  as  additional  arguments.  callback 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 -v option causes the	output	to  be
	      assigned	to  the	 variable var rather than being printed to the
	      standard output.

	      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 format specifications, each
	      of which causes printing of the next  successive	argument.   In
	      addition to the standard printf(1) format specifications, printf
	      interprets the following extensions:
	      %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).
	      %q     causes  printf  to output the corresponding argument in a
		     format that can be reused as shell input.
	      %(datefmt)T
		     causes printf to output the  date-time  string  resulting
		     from  using  datefmt  as a format string for strftime(3).
		     The corresponding argument is an integer representing the
		     number  of seconds since the epoch.  Two special argument
		     values may be used: -1 represents the current  time,  and
		     -2 represents the time the shell was invoked.

	      Arguments	 to non-string format specifiers are treated as C con-
	      stants, except that a leading plus or minus sign is allowed, and
	      if  the leading character is a single or double quote, the value
	      is the ASCII value of the following character.

	      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 [-aAf] [-p] [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 both options are supplied, -A takes precedence.  If
	      no name arguments are given, or if the -p option is supplied,  a
	      list of all readonly names is printed.  The other options may be
	      used to restrict the output to a subset of the set  of  readonly
	      names.   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-name] [arg ...]
       set [+abefhkmnptuvxBCEHPT] [+o option-name] [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 COL-
		      UMNS.
	      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
		      command'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.
		      Bash  versions prior to bash-4.1 use ASCII collation and
		      strcmp(3); bash-4.1 and later use the  current  locale's
		      collation sequence and strcoll(3).
	      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
		      (see previous item) and the  effect  of  interrupting  a
		      command list.
	      compat41
		      If  set, bash, when in posix mode, treats a single quote
		      in a double-quoted  parameter  expansion	as  a  special
		      character.   The	single quotes must match (an even num-
		      ber) and the characters between the  single  quotes  are
		      considered  quoted.   This is the behavior of posix mode
		      through version 4.1.  The default bash behavior  remains
		      as in previous versions.
	      direxpand
		      If  set,	bash replaces directory names with the results
		      of word expansion when performing	 filename  completion.
		      This  changes  the contents of the readline editing buf-
		      fer.  If not set, bash attempts  to  preserve  what  the
		      user typed.
	      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 ERR 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 all 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.
	      lastpipe
		      If set, and job control is not active,  the  shell  runs
		      the last command of a pipeline not executed in the back-
		      ground in the current shell environment.
	      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.  Operator prece-
	      dence is used when there are five or more arguments.
	      ! 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
		     The following conditions are applied in the order listed.
		     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.

	      When  used  with	test  or [, the < and > operators sort lexico-
	      graphically using ASCII ordering.

       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 and, on some systems, to its children
	      -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)