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, return,  break,  con-
       tinue,  let,  and shift builtins accept and process arguments beginning
       with -- without 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  interpreta-
       tion.
       :: [arguments]
              No  effect;  the command does nothing beyond expanding arguments
              and performing any specified redirections.  The return status is
              zero.

        ..  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,
              filenames in PATH are used  to  find  the  directory  containing
              filename.  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.   If  the  -T  option is
              enabled, source inherits any trap on DEBUG; if it  is  not,  any
              DEBUG  trap  string  is  saved  and  restored around the call to
              source, and source unsets the DEBUG trap while it executes.   If
              -T  is not set, and the sourced file changes the DEBUG trap, the
              new value is retained when source completes.  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] [-lpsvPSVX]
       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 [-m keymap] keyseq: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.
              -X     List  all  key  sequences bound to shell commands and the
                     associated commands in a format that  can  be  reused  as
                     input.

              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 0 unless _n is not greater than or
              equal to 1.

       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.  if dir is not supplied,
              the value of the HOME shell variable is the default.  Any  addi-
              tional arguments following dir are ignored.  The variable CDPATH
              defines the search path for the directory containing  dir:  each
              directory  name  in  CDPATH  is  searched  for 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  causes cd to use the physical directory
              structure by resolving symbolic links while traversing  dir  and
              before processing instances of .. in dir (see also the -P option
              to the set builtin command); the -L option forces symbolic links
              to  be followed by resolving the link after processing instances
              of .. in dir.  If .. appears in dir, it is processed by removing
              the  immediately previous pathname component from dir, back to a
              slash or the beginning of dir.  If the  -e  option  is  supplied
              with  -P,  and  the current working directory cannot be success-
              fully determined after a successful directory  change,  cd  will
              return  an unsuccessful status.  On systems that support it, the
              --@@ option presents the extended  attributes  associated  with  a
              file  as  a directory.  An argument of -- is converted to $OLDPWD
              before the directory change is attempted.  If a non-empty direc-
              tory  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  successfully
              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 filename
              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.
                      noquote Tell  readline  not to quote the completed words
                              if they are filenames (quoting filenames is  the
                              default).
                      nosort  Tell  readline  not to sort the list of possible
                              completions alphabetically.
                      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 the function is  executed,  the
                      first  argument  ($$11)  is  the name of the command whose
                      arguments are being completed, the second argument  ($$22)
                      is the word being completed, and the third argument ($$33)
                      is the word preceding the word being  completed  on  the
                      current  command  line.   When it finishes, the possible
                      completions are retrieved from the value of the  COMPRE-
                      PLY 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] [++oo 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.  The return value is 0 unless _n is not greater
              than or equal to 1.

       declare [-aAfFgilnrtux] [-p] [name[=value] ...]
       typeset [-aAfFgilnrtux] [-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, other than -f and -F,
              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 definitions; 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 each name is defined are displayed 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  follow-
              ing 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.
              -n     Give each name the nameref attribute, making  it  a  name
                     reference  to  another  variable.  That other variable is
                     defined by the value of name.   All  references,  assign-
                     ments,  and  attribute  modifications to name, except for
                     changing the -n attribute itself, are  performed  on  the
                     variable   referenced   by  name's  value.   The  nameref
                     attribute cannot be applied to array variables.
              -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, declare and typeset make each name local, as with
              the local command, unless the -g option is supplied.  If a vari-
              able name is followed by =value, the value of  the  variable  is
              set  to  value.  When using -a or -A and the compound assignment
              syntax to create array variables, additional attributes  do  not
              take effect until subsequent assignments.  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 read-
              only 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 [-clpv] [[++_n]] [[--_n]]
              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.  The  current  directory  is  always  the
              first directory in the stack.
              -c     Clears  the  directory  stack  by  deleting  all  of  the
                     entries.
              -l     Produces a listing  using  full  pathnames;  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.
              ++_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.

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

       echo [-neE] [arg ...]
              Output  the  args,  separated  by spaces, followed by a newline.
              The return status is 0 unless a write error occurs.   If  -n  is
              specified, the trailing newline is suppressed.  If the -e option
              is given,  interpretation  of  the  following  backslash-escaped
              characters  is  enabled.  The -E option disables the interpreta-
              tion of these escape characters, 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
              \\00nnn  the  eight-bit  character  whose value is the octal value
                     nnn (zero to three octal digits)
              \\xx_H_H   the eight-bit character whose value  is  the  hexadecimal
                     value HH (one or two hex digits)
              \\uuHHHH the  Unicode (ISO/IEC 10646) character whose value is the
                     hexadecimal value HHHH (one to four hex digits)
              \\UUHHHHHHHH
                     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 execfail shell option is enabled.  In that  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 names of all exported
              variables 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  sup-
              plied with a name that is not a function.

       fc [-e ename] [-lnr] [first] [last]
       fc -s [pat=rep] [cmd]
              The  first  form  selects a range of commands from first to last
              from the history list and  displays  or  edits  and  re-executes
              them.   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 current 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  other-
              wise.   If first is not specified it is set to the previous com-
              mand 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, vi is used.  When  editing  is  com-
              plete, the edited commands are echoed and executed.

              In  the  second form, command is re-executed after each instance
              of pat is replaced by rep.  Command is intepreted  the  same  as
              first  above.  A useful alias to use with this is ``r="fc -s"'',
              so that typing ``r c' runs the  last  command  beginning  with
              `c' and typing ``r'' re-executes the last command.

              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  filename 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  to  the  history  file.
                     These  are  history  lines entered since the beginning of
                     the current bash session, but not already appended 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 append them  to
                     the current history list.
              -w     Write the current history list to the history file, over-
                     writing 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     Display only running jobs.
              -s     Display only 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|-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.  The  -L  option  is
              equivalent  to -l.  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.  If name is -, the set of shell options
              is made local to the function in which local is  invoked:  shell
              options  changed  using  the set builtin inside the function are
              restored to their original values  when  the  function  returns.
              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  [-d  delim] [-n count] [-O origin] [-s count] [-t] [-u fd] [-C
       callback] [-c quantum] [array]
       readarray [-d delim] [-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:
              -d     The first character of delim is used  to  terminate  each
                     input line, rather than newline.
              -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 delim (default 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 [-nn] [+_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 \\00 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))TT
                     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.   If  no
                     argument  is  specified,  conversion behaves as if -1 had
                     been given.  This is an exception  to  the  usual  printf
                     behavior.

              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,  pushd  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  rotating
                     or  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 as if it had been supplied
                     as the argument to the cd builtin.

              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 using the same rules the shell uses
              for expansion (described above under Word Splitting).  The back-
              slash  character  (\\)  may be used to remove any special meaning
              for the next character read and for line continuation.  Options,
              if supplied, have the following 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 honors 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.   The result is not split on the characters in
                     IFS; the intent is that the variable is assigned  exactly
                     the characters read (with the exception of backslash; see
                     the -r option below).
              -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  (or a specified number of characters) is
                     not read within timeout seconds.  timeout may be a  deci-
                     mal  number with a fractional portion following the deci-
                     mal point.  This option is  only  effective  if  read  is
                     reading  input  from  a  terminal, pipe, or other special
                     file; it has no effect when reading from  regular  files.
                     If read times out, read saves any partial input read into
                     the specified variable  name.   If  timeout  is  0,  read
                     returns  immediately,  without  trying  to read any data.
                     The exit status is 0 if input is available on the  speci-
                     fied  file descriptor, non-zero otherwise.  The exit sta-
                     tus 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  exit  status  is zero, unless end-of-file is
              encountered, read times out (in which case the status is greater
              than  128),  a variable assignment error (such as assigning to a
              readonly variable) occurs, or an invalid file descriptor is sup-
              plied 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 stop executing and return the value speci-
              fied by _n to its caller.  If _n is omitted, the return status  is
              that  of  the  last  command  executed in the function body.  If
              return is executed by a trap handler, the last command  used  to
              determine  the  status  is  the last command executed before the
              trap handler.  if return is executed during a  DEBUG  trap,  the
              last  command  used  to determine the status is the last command
              executed by the trap handler  before  return  was  invoked.   If
              return  is  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 _n is supplied, the return value is its least
              significant 8 bits.  The return status is non-zero if return  is
              supplied  a  non-numeric argument, or is used outside a function
              and not during execution of a script by .. or source.   Any  com-
              mand  associated  with the RETURN trap is executed before execu-
              tion resumes after the function or script.

       set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]
       set [+abefhkmnptuvxBCEHPT] [++oo 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
              $$11, $$22, ......  $$_n.  Options,  if  specified,  have  the  following
              meanings:
              -a      Each variable or function that is created or modified is
                      given the export attribute and marked 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 list, or  a  compound  command
                      (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 !!.   If  a
                      compound  command  other  than a subshell returns a non-
                      zero status because a command failed while -e was  being
                      ignored,  the  shell  does  not exit.  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.

                      If a compound command or shell function  executes  in  a
                      context  where -e is being ignored, none of the commands
                      executed within the compound command  or  function  body
                      will  be  affected  by the -e setting, even if -e is set
                      and a command returns a failure status.  If  a  compound
                      command  or  shell function sets -e while executing in a
                      context where -e is ignored, that setting will not  have
                      any  effect  until  the  compound command or the command
                      containing the function call completes.
              -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).  All processes run
                      in a separate process group.  When a background job com-
                      pletes, the shell prints a line containing its exit sta-
                      tus.
              -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).  See  SEE  ALSO
                              below for a reference to a document that details
                              how posix mode affects bash's behavior.
                      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 resolve 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  $$11  ........
              Parameters  represented  by  the  numbers  $$## 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 settings controlling optional shell  behav-
              ior.   The settings can be either those listed below, or, if the
              -o option is used, those available with the -o option to the set
              builtin command.  With no options, or with the -p option, a list
              of all settable 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 following 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,  shopt
              shows  only  those options which are set or unset, respectively.
              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 filename 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 and locale-specific string compar-
                      ison  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 cur-
                      rent locale's collation sequence and strcoll(3).
              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
                      (see previous item).
              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 description of compat31) and the effect  of  inter-
                      rupting  a  command  list.   Bash versions 4.0 and later
                      interrupt the list as if the shell received  the  inter-
                      rupt;  previous  versions continue with the next command
                      in the 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.
              compat42
                      If set, bash does not process the replacement string  in
                      the  pattern  substitution  word  expansion  using quote
                      removal.
              compat43
                      If set, bash does not print  a  warning  message  if  an
                      attempt  is  made to use a quoted compound array assign-
                      ment as an argument to declare, and makes word expansion
                      errors  non-fatal  errors that cause the current command
                      to fail (the default behavior  is  to  make  them  fatal
                      errors that cause the shell to exit).
              complete_fullquote
                      If  set,  bash  quotes all shell metacharacters in file-
                      names and directory names  when  performing  completion.
                      If not set, bash removes metacharacters such as the dol-
                      lar sign from the set of characters that will be  quoted
                      in  completed filenames when these metacharacters appear
                      in shell variable references in words to  be  completed.
                      This  means  that  dollar  signs  in variable names that
                      expand to directories will not be quoted;  however,  any
                      dollar  signs appearing in filenames will not be quoted,
                      either.  This is active only when bash  is  using  back-
                      slashes  to quote completed filenames.  This variable is
                      set by default, which is the default  bash  behavior  in
                      versions through 4.2.
              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:
                      11..     The -F option to the declare builtin displays the
                             source file name and line number corresponding to
                             each function name supplied as an argument.
                      22..     If the command run by the DEBUG  trap  returns  a
                             non-zero  value,  the next command is skipped and
                             not executed.
                      33..     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), the shell
                             simulates a call to return.
                      44..     BASH_ARGC and BASH_ARGV are updated as  described
                             in their descriptions above.
                      55..     Function  tracing  is  enabled: command substitu-
                             tion, shell functions, and subshells invoked with
                             (( command )) inherit the DEBUG and RETURN traps.
                      66..     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.
              globasciiranges
                      If set,  range  expressions  used  in  pattern  matching
                      bracket  expressions (see Pattern Matching above) behave
                      as if in the traditional C locale when  performing  com-
                      parisons.   That  is,  the  current  locale's  collating
                      sequence is not taken into account, so bb will  not  col-
                      late  between  AA  and  BB,  and upper-case and lower-case
                      ASCII characters will collate together.
              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, when performing pattern substi-
                      tution word expansions, or when filtering possible  com-
                      pletions as part of programmable completion.
              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.  A login shell cannot be suspended; the -f option can be
              used to override this and force the suspension.  The return sta-
              tus is 0 unless the shell is a login shell and -f  is  not  sup-
              plied, or if job control is not enabled.

       test expr
       [[ expr ]]
              Return a status of 0 (true) or 1 (false) depending on the evalu-
              ation of the conditional expression expr.  Each operator and op-
              erand  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 -aa expr2
                     True if both expr1 and expr2 are true.
              expr1 -oo 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  a
              pipeline (which may consist of a single simple command), a list,
              or a compound command returns 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 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  using
              !!.   These  are  the  same conditions obeyed by the errexit (-e)
              option.

              Signals ignored upon entry to the shell  cannot  be  trapped  or
              reset.   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, which is not necessar-
              ily 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
              function lookup, as with the command builtin.  type returns true
              if all of the arguments are found, false if any are not found.

       ulimit [-HSabcdefiklmnpqrstuvxPT [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
              -k     The maximum number of kqueues that may be allocated
              -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
              -P     The maximum number of pseudoterminals
              -T     The maximum number of threads

              If  limit  is given, and the -a option is not used, limit is the
              new value of the specified resource.  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;  -P,  -T, -b, -k, -n, and -u, which are unscaled values;
              and, when in Posix mode, -c and -f, which are in 512-byte incre-
              ments.  The return status is 0 unless an invalid option or argu-
              ment is supplied, or an error occurs while setting a new limit.

       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 [-aa] [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] [-nn] [name ...]
              For  each  name,  remove the corresponding variable or function.
              If the -v option is given, each name refers to a shell variable,
              and  that  variable  is removed.  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.  If the -n option
              is supplied, and name is a variable with the nameref  attribute,
              name  will  be unset rather than the variable it references.  -n
              has no effect if the -f option is supplied.  If no  options  are
              supplied,  each  name refers to a variable; if there is no vari-
              able by that name, any function with that name is  unset.   Each
              unset  variable  or  function  is  removed  from the environment
              passed to subsequent commands.  If any of COMP_WORDBREAKS,  RAN-
              DOM, SECONDS, LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are
              unset, they lose their special properties, even if they are sub-
              sequently reset.  The exit status is true unless a name is read-
              only.

       wait [-n] [_n _._._.]
              Wait for each specified child process and return its termination
              status.  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 the -n
              option  is  supplied,  wait  waits  for any job to terminate and
              returns its exit status.  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-4.2                      2004 Apr 20                 BASH_BUILTINS(1)
