path: root/doc/builtins.0

BASH_BUILTINS(1)                                              BASH_BUILTINS(1)



NNAAMMEE
       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 bbaasshh(1)

BBAASSHH BBUUIILLTTIINN CCOOMMMMAANNDDSS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by -- accepts ---- to signify the end of the
       options.   The  ::, ttrruuee, ffaallssee, and tteesstt builtins do not accept options
       and do not treat ---- specially.  The eexxiitt, llooggoouutt, bbrreeaakk, ccoonnttiinnuuee, lleett,
       and  sshhiifftt builtins accept and process arguments beginning with -- with-
       out requiring ----.  Other builtins that accept  arguments  but  are  not
       specified  as accepting options interpret arguments beginning with -- as
       invalid options and require ---- to prevent this interpretation.
       :: [_a_r_g_u_m_e_n_t_s]
              No effect; the command does nothing beyond  expanding  _a_r_g_u_m_e_n_t_s
              and  performing any specified redirections.  A zero exit code is
              returned.

        ..  _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
       ssoouurrccee _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
              Read and execute commands from _f_i_l_e_n_a_m_e  in  the  current  shell
              environment  and return the exit status of the last command exe-
              cuted from _f_i_l_e_n_a_m_e.  If _f_i_l_e_n_a_m_e does not contain a slash, file
              names  in  PPAATTHH  are used to find the directory containing _f_i_l_e_-
              _n_a_m_e.  The file searched for in PPAATTHH  need  not  be  executable.
              When  bbaasshh  is  not  in  _p_o_s_i_x  _m_o_d_e,  the  current directory is
              searched if no file is found in PPAATTHH.  If the ssoouurrcceeppaatthh  option
              to  the  sshhoopptt  builtin  command  is turned off, the PPAATTHH is not
              searched.  If any _a_r_g_u_m_e_n_t_s are supplied, they become the  posi-
              tional  parameters  when  _f_i_l_e_n_a_m_e  is  executed.  Otherwise the
              positional parameters are unchanged.  The return status  is  the
              status  of  the  last  command exited within the script (0 if no
              commands are executed), and false if _f_i_l_e_n_a_m_e is  not  found  or
              cannot be read.

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

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

       bbiinndd [--mm _k_e_y_m_a_p] [--llppssvvPPSSVV]
       bbiinndd [--mm _k_e_y_m_a_p] [--qq _f_u_n_c_t_i_o_n] [--uu _f_u_n_c_t_i_o_n] [--rr _k_e_y_s_e_q]
       bbiinndd [--mm _k_e_y_m_a_p] --ff _f_i_l_e_n_a_m_e
       bbiinndd [--mm _k_e_y_m_a_p] --xx _k_e_y_s_e_q:_s_h_e_l_l_-_c_o_m_m_a_n_d
       bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_f_u_n_c_t_i_o_n_-_n_a_m_e
       bbiinndd _r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d
              Display current rreeaaddlliinnee key and function bindings, bind  a  key
              sequence  to  a  rreeaaddlliinnee  function  or macro, or set a rreeaaddlliinnee
              variable.  Each non-option argument is a  command  as  it  would
              appear  in  _._i_n_p_u_t_r_c, 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:
              --mm _k_e_y_m_a_p
                     Use _k_e_y_m_a_p as the keymap to be affected by the subsequent
                     bindings.  Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_-
                     _d_a_r_d_,  _e_m_a_c_s_-_m_e_t_a_,  _e_m_a_c_s_-_c_t_l_x_,  _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d,
                     and _v_i_-_i_n_s_e_r_t.  _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s  is
                     equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d.
              --ll     List the names of all rreeaaddlliinnee functions.
              --pp     Display  rreeaaddlliinnee  function  names and bindings in such a
                     way that they can be re-read.
              --PP     List current rreeaaddlliinnee function names and bindings.
              --ss     Display rreeaaddlliinnee key sequences bound to  macros  and  the
                     strings  they  output  in such a way that they can be re-
                     read.
              --SS     Display rreeaaddlliinnee key sequences bound to  macros  and  the
                     strings they output.
              --vv     Display  rreeaaddlliinnee variable names and values in such a way
                     that they can be re-read.
              --VV     List current rreeaaddlliinnee variable names and values.
              --ff _f_i_l_e_n_a_m_e
                     Read key bindings from _f_i_l_e_n_a_m_e.
              --qq _f_u_n_c_t_i_o_n
                     Query about which keys invoke the named _f_u_n_c_t_i_o_n.
              --uu _f_u_n_c_t_i_o_n
                     Unbind all keys bound to the named _f_u_n_c_t_i_o_n.
              --rr _k_e_y_s_e_q
                     Remove any current binding for _k_e_y_s_e_q.
              --xx _k_e_y_s_e_q::_s_h_e_l_l_-_c_o_m_m_a_n_d
                     Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be  executed  whenever  _k_e_y_s_e_q  is
                     entered.   When _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets
                     the RREEAADDLLIINNEE__LLIINNEE variable to the contents of  the  rreeaadd--
                     lliinnee  line  buffer and the RREEAADDLLIINNEE__PPOOIINNTT variable to the
                     current location of the insertion point.  If the executed
                     command  changes  the  value  of  RREEAADDLLIINNEE__LLIINNEE  or RREEAADD--
                     LLIINNEE__PPOOIINNTT, those new values will  be  reflected  in  the
                     editing state.

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

       bbrreeaakk [_n]
              Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt 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.

       bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s]
              Execute the specified shell builtin, passing it  _a_r_g_u_m_e_n_t_s,  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 ccdd builtin is
              commonly redefined this way.  The  return  status  is  false  if
              _s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command.

       ccaalllleerr [_e_x_p_r]
              Returns the context of any active subroutine call (a shell func-
              tion or a script executed with the .. or ssoouurrccee builtins.   With-
              out _e_x_p_r, ccaalllleerr displays the line number and source filename of
              the current subroutine call.  If a non-negative integer is  sup-
              plied as _e_x_p_r, ccaalllleerr 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 _e_x_p_r does not correspond to a valid position  in
              the call stack.

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

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

       ccoommppggeenn [_o_p_t_i_o_n] [_w_o_r_d]
              Generate  possible  completion matches for _w_o_r_d according to the
              _o_p_t_i_o_ns, which may  be  any  option  accepted  by  the  ccoommpplleettee
              builtin  with  the exception of --pp and --rr, and write the matches
              to the standard output.  When using the --FF or  --CC  options,  the
              various  shell  variables  set  by  the  programmable completion
              facilities, while available, will not have useful values.

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

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

       ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--DDEE] [--AA _a_c_t_i_o_n]  [--GG  _g_l_o_b_-
       _p_a_t] [--WW _w_o_r_d_l_i_s_t] [--FF _f_u_n_c_t_i_o_n] [--CC _c_o_m_m_a_n_d]
              [--XX _f_i_l_t_e_r_p_a_t] [--PP _p_r_e_f_i_x] [--SS _s_u_f_f_i_x] _n_a_m_e [_n_a_m_e _._._.]
       ccoommpplleettee --pprr [--DDEE] [_n_a_m_e ...]
              Specify how arguments to each _n_a_m_e should be completed.  If  the
              --pp  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 --rr option removes a completion spec-
              ification for each _n_a_m_e, or, if no _n_a_m_es are supplied, all  com-
              pletion  specifications.   The  --DD  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  --EE
              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  PPrroo--
              ggrraammmmaabbllee CCoommpplleettiioonn.

              Other  options,  if specified, have the following meanings.  The
              arguments to the --GG, --WW, and --XX options (and, if necessary,  the
              --PP  and --SS options) should be quoted to protect them from expan-
              sion before the ccoommpplleettee builtin is invoked.
              --oo _c_o_m_p_-_o_p_t_i_o_n
                      The _c_o_m_p_-_o_p_t_i_o_n controls several aspects  of  the  comp-
                      spec's  behavior beyond the simple generation of comple-
                      tions.  _c_o_m_p_-_o_p_t_i_o_n may be one of:
                      bbaasshhddeeffaauulltt
                              Perform the rest of the default bbaasshh completions
                              if the compspec generates no matches.
                      ddeeffaauulltt Use  readline's  default  filename completion if
                              the compspec generates no matches.
                      ddiirrnnaammeess
                              Perform directory name completion if  the  comp-
                              spec generates no matches.
                      ffiilleennaammeess
                              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.
                      nnoossppaaccee Tell  readline  not  to  append  a  space   (the
                              default)  to  words  completed at the end of the
                              line.
                      pplluussddiirrss
                              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.
              --AA _a_c_t_i_o_n
                      The  _a_c_t_i_o_n  may  be  one of the following to generate a
                      list of possible completions:
                      aalliiaass   Alias names.  May also be specified as --aa.
                      aarrrraayyvvaarr
                              Array variable names.
                      bbiinnddiinngg RReeaaddlliinnee key binding names.
                      bbuuiillttiinn Names of shell builtin commands.   May  also  be
                              specified as --bb.
                      ccoommmmaanndd Command names.  May also be specified as --cc.
                      ddiirreeccttoorryy
                              Directory names.  May also be specified as --dd.
                      ddiissaabblleedd
                              Names of disabled shell builtins.
                      eennaabblleedd Names of enabled shell builtins.
                      eexxppoorrtt  Names  of exported shell variables.  May also be
                              specified as --ee.
                      ffiillee    File names.  May also be specified as --ff.
                      ffuunnccttiioonn
                              Names of shell functions.
                      ggrroouupp   Group names.  May also be specified as --gg.
                      hheellppttooppiicc
                              Help topics as accepted by the hheellpp builtin.
                      hhoossttnnaammee
                              Hostnames, as taken from the file  specified  by
                              the HHOOSSTTFFIILLEE shell variable.
                      jjoobb     Job  names,  if job control is active.  May also
                              be specified as --jj.
                      kkeeyywwoorrdd Shell reserved words.  May also be specified  as
                              --kk.
                      rruunnnniinngg Names of running jobs, if job control is active.
                      sseerrvviiccee Service names.  May also be specified as --ss.
                      sseettoopptt  Valid arguments for the --oo  option  to  the  sseett
                              builtin.
                      sshhoopptt   Shell  option  names  as  accepted  by the sshhoopptt
                              builtin.
                      ssiiggnnaall  Signal names.
                      ssttooppppeedd Names of stopped jobs, if job control is active.
                      uusseerr    User names.  May also be specified as --uu.
                      vvaarriiaabbllee
                              Names of all shell variables.  May also be spec-
                              ified as --vv.
              --GG _g_l_o_b_p_a_t
                      The pathname expansion pattern _g_l_o_b_p_a_t  is  expanded  to
                      generate the possible completions.
              --WW _w_o_r_d_l_i_s_t
                      The  _w_o_r_d_l_i_s_t  is  split using the characters in the IIFFSS
                      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.
              --CC _c_o_m_m_a_n_d
                      _c_o_m_m_a_n_d  is  executed in a subshell environment, and its
                      output is used as the possible completions.
              --FF _f_u_n_c_t_i_o_n
                      The shell function _f_u_n_c_t_i_o_n is executed in  the  current
                      shell  environment.  When it finishes, the possible com-
                      pletions are retrieved from the value of  the  CCOOMMPPRREEPPLLYY
                      array variable.
              --XX _f_i_l_t_e_r_p_a_t
                      _f_i_l_t_e_r_p_a_t  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 _f_i_l_t_e_r_p_a_t is removed from the  list.
                      A  leading  !!  in _f_i_l_t_e_r_p_a_t negates the pattern; in this
                      case, any completion not matching _f_i_l_t_e_r_p_a_t is  removed.
              --PP _p_r_e_f_i_x
                      _p_r_e_f_i_x  is  added at the beginning of each possible com-
                      pletion after all other options have been applied.
              --SS _s_u_f_f_i_x
                      _s_u_f_f_i_x is appended to each possible completion after all
                      other options have been applied.

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

       ccoommppoopptt [--oo _o_p_t_i_o_n] [--DDEE] [++oo _o_p_t_i_o_n] [_n_a_m_e]
              Modify  completion  options  for  each  _n_a_m_e  according  to  the
              _o_p_t_i_o_ns, or for the currently-execution completion if  no  _n_a_m_es
              are  supplied.   If no _o_p_t_i_o_ns are given, display the completion
              options for each _n_a_m_e or the current completion.   The  possible
              values  of  _o_p_t_i_o_n  are  those  valid  for  the ccoommpplleettee builtin
              described above.  The --DD 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 --EE 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 _n_a_m_e for which  no  comple-
       tion specification exists, or an output error occurs.

       ccoonnttiinnuuee [_n]
              Resume the next iteration of the enclosing ffoorr, wwhhiillee, uunnttiill, or
              sseelleecctt 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.

       ddeeccllaarree [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
       ttyyppeesseett [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
              Declare variables and/or give them attributes.  If no _n_a_m_es  are
              given  then display the values of variables.  The --pp option will
              display the attributes and values of each _n_a_m_e.  When --pp is used
              with _n_a_m_e arguments, additional options are ignored.  When --pp is
              supplied without _n_a_m_e 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
              --pp,  ddeeccllaarree will display the attributes and values of all shell
              variables.  The --ff option will restrict  the  display  to  shell
              functions.  The --FF option inhibits the display of function defi-
              nitions; only the function name and attributes are printed.   If
              the  eexxttddeebbuugg  shell  option  is enabled using sshhoopptt, the source
              file name and line number where the function is defined are dis-
              played  as  well.   The  --FF  option  implies  --ff.  The following
              options can be used to restrict output  to  variables  with  the
              specified attribute or to give variables attributes:
              --aa     Each  _n_a_m_e  is  an  indexed  array  variable  (see AArrrraayyss
                     above).
              --AA     Each _n_a_m_e is an associative array  variable  (see  AArrrraayyss
                     above).
              --ff     Use function names only.
              --ii     The variable is treated as an integer; arithmetic evalua-
                     tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed  when
                     the variable is assigned a value.
              --ll     When  the  variable  is  assigned a value, all upper-case
                     characters are converted to lower-case.   The  upper-case
                     attribute is disabled.
              --rr     Make _n_a_m_es readonly.  These names cannot then be assigned
                     values by subsequent assignment statements or unset.
              --tt     Give each _n_a_m_e the  _t_r_a_c_e  attribute.   Traced  functions
                     inherit  the  DDEEBBUUGG  and  RREETTUURRNN  traps  from the calling
                     shell.  The trace attribute has no  special  meaning  for
                     variables.
              --uu     When  the  variable  is  assigned a value, all lower-case
                     characters are converted to upper-case.   The  lower-case
                     attribute is disabled.
              --xx     Mark  _n_a_m_es  for  export  to  subsequent commands via the
                     environment.

              Using `+' instead of `-' turns off the attribute  instead,  with
              the exceptions that ++aa may not be used to destroy an array vari-
              able and ++rr will not remove the readonly attribute.   When  used
              in a function, makes each _n_a_m_e local, as with the llooccaall command.
              If a variable name is followed by =_v_a_l_u_e, the value of the vari-
              able  is  set to _v_a_l_u_e.  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
              AArrrraayyss above), one of the _n_a_m_e_s is not a  valid  shell  variable
              name, an attempt is made to turn off readonly status for a read-
              only variable, an attempt is made to turn off array  status  for
              an  array variable, or an attempt is made to display a non-exis-
              tent function with --ff.

       ddiirrss [[++_n]] [[--_n]] [[--ccppllvv]]
              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  ppuusshhdd  command;  the  ppooppdd command removes
              entries from the list.
              ++_n     Displays the _nth entry counting from the left of the list
                     shown by ddiirrss when invoked without options, starting with
                     zero.
              --_n     Displays the _nth entry counting from  the  right  of  the
                     list shown by ddiirrss when invoked without options, starting
                     with zero.
              --cc     Clears  the  directory  stack  by  deleting  all  of  the
                     entries.
              --ll     Produces  a  longer  listing;  the default listing format
                     uses a tilde to denote the home directory.
              --pp     Print the directory stack with one entry per line.
              --vv     Print the directory stack with one entry per  line,  pre-
                     fixing each entry with its index in the stack.

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

       ddiissoowwnn [--aarr] [--hh] [_j_o_b_s_p_e_c ...]
              Without options, each _j_o_b_s_p_e_c  is  removed  from  the  table  of
              active  jobs.   If _j_o_b_s_p_e_c is not present, and neither --aa nor --rr
              is supplied, the shell's notion of the _c_u_r_r_e_n_t _j_o_b is used.   If
              the --hh option is given, each _j_o_b_s_p_e_c is not removed from the ta-
              ble, but is marked so that SSIIGGHHUUPP is not sent to the job if  the
              shell  receives a SSIIGGHHUUPP.  If no _j_o_b_s_p_e_c is present, and neither
              the --aa nor the --rr option is supplied, the _c_u_r_r_e_n_t _j_o_b  is  used.
              If no _j_o_b_s_p_e_c is supplied, the --aa option means to remove or mark
              all jobs; the --rr option without  a  _j_o_b_s_p_e_c  argument  restricts
              operation  to running jobs.  The return value is 0 unless a _j_o_b_-
              _s_p_e_c does not specify a valid job.

       eecchhoo [--nneeEE] [_a_r_g ...]
              Output the _a_r_gs, separated by spaces,  followed  by  a  newline.
              The return status is always 0.  If --nn is specified, the trailing
              newline is suppressed.  If the --ee option is  given,  interpreta-
              tion  of  the following backslash-escaped characters is enabled.
              The --EE option disables the interpretation of these escape  char-
              acters,  even  on systems where they are interpreted by default.
              The xxppgg__eecchhoo shell option may be used to  dynamically  determine
              whether  or not eecchhoo expands these escape characters by default.
              eecchhoo does not interpret ---- to mean the  end  of  options.   eecchhoo
              interprets the following escape sequences:
              \\aa     alert (bell)
              \\bb     backspace
              \\cc     suppress further output
              \\ee     an escape character
              \\ff     form feed
              \\nn     new line
              \\rr     carriage return
              \\tt     horizontal tab
              \\vv     vertical tab
              \\\\     backslash
              \\00_n_n_n  the  eight-bit  character  whose value is the octal value
                     _n_n_n (zero to three octal digits)
              \\xx_H_H   the eight-bit character whose value  is  the  hexadecimal
                     value _H_H (one or two hex digits)

       eennaabbllee [--aa] [--ddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...]
              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  --nn  is  used,  each  _n_a_m_e  is disabled; otherwise, _n_a_m_e_s are
              enabled.  For example, to use the tteesstt binary found via the PPAATTHH
              instead  of  the  shell builtin version, run ``enable -n test''.
              The --ff option means to load the new builtin  command  _n_a_m_e  from
              shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading.
              The --dd option will delete a builtin previously loaded  with  --ff.
              If no _n_a_m_e arguments are given, or if the --pp 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 --nn
              is supplied, only disabled builtins are printed.  If --aa is  sup-
              plied,  the  list printed includes all builtins, with an indica-
              tion of whether or not each is enabled.  If --ss is supplied,  the
              output  is restricted to the POSIX _s_p_e_c_i_a_l builtins.  The return
              value is 0 unless a _n_a_m_e is not a shell builtin or there  is  an
              error loading a new builtin from a shared object.

       eevvaall [_a_r_g ...]
              The  _a_r_gs  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 eevvaall.  If there are
              no _a_r_g_s, or only null arguments, eevvaall returns 0.

       eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]]
              If _c_o_m_m_a_n_d is specified, it replaces the shell.  No new  process
              is  created.  The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d.  If
              the --ll option is supplied, the shell places a dash at the begin-
              ning  of  the  zeroth  argument passed to _c_o_m_m_a_n_d.  This is what
              _l_o_g_i_n(1) does.  The --cc option causes _c_o_m_m_a_n_d to be executed with
              an  empty environment.  If --aa is supplied, the shell passes _n_a_m_e
              as the zeroth argument to the executed command.  If _c_o_m_m_a_n_d can-
              not  be executed for some reason, a non-interactive shell exits,
              unless the shell option eexxeeccffaaiill is enabled, in  which  case  it
              returns  failure.   An  interactive shell returns failure if the
              file cannot be executed.  If _c_o_m_m_a_n_d 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.

       eexxiitt [_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
              EEXXIITT is executed before the shell terminates.

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

       ffcc [--ee _e_n_a_m_e] [--llnnrr] [_f_i_r_s_t] [_l_a_s_t]
       ffcc --ss [_p_a_t=_r_e_p] [_c_m_d]
              Fix  Command.  In the first form, a range of commands from _f_i_r_s_t
              to _l_a_s_t is selected from the history list.  _F_i_r_s_t and  _l_a_s_t  may
              be  specified  as a string (to locate the last command beginning
              with that string) or as a number  (an  index  into  the  history
              list, where a negative number is used as an offset from the cur-
              rent command number).  If _l_a_s_t is not specified it is set to the
              current  command  for  listing (so that ``fc -l -10'' prints the
              last 10 commands) and to _f_i_r_s_t otherwise.  If _f_i_r_s_t is not spec-
              ified  it is set to the previous command for editing and -16 for
              listing.

              The --nn option suppresses the command numbers when listing.   The
              --rr  option reverses the order of the commands.  If the --ll option
              is given, the commands are listed on  standard  output.   Other-
              wise,  the editor given by _e_n_a_m_e is invoked on a file containing
              those commands.  If _e_n_a_m_e is not given, the value of the  FFCCEEDDIITT
              variable  is used, and the value of EEDDIITTOORR if FFCCEEDDIITT is not set.
              If neither variable is set, is used.  When editing is  complete,
              the edited commands are echoed and executed.

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

              If  the  first  form  is  used,  the return value is 0 unless an
              invalid option is encountered or _f_i_r_s_t or _l_a_s_t  specify  history
              lines  out  of  range.  If the --ee 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  _c_m_d  does  not  specify a valid history line, in
              which case ffcc returns failure.

       ffgg [_j_o_b_s_p_e_c]
              Resume _j_o_b_s_p_e_c in the foreground, and make it the  current  job.
              If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b
              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 _j_o_b_s_p_e_c does not spec-
              ify  a  valid  job  or  _j_o_b_s_p_e_c specifies a job that was started
              without job control.

       ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g_s]
              ggeettooppttss is used by shell procedures to parse positional  parame-
              ters.   _o_p_t_s_t_r_i_n_g  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, ggeettooppttss
              places the next option in the shell variable _n_a_m_e,  initializing
              _n_a_m_e if it does not exist, and the index of the next argument to
              be processed into the variable OOPPTTIINNDD.  OOPPTTIINNDD is initialized to
              1  each  time  the  shell or a shell script is invoked.  When an
              option requires an argument, ggeettooppttss places that  argument  into
              the  variable OOPPTTAARRGG.  The shell does not reset OOPPTTIINNDD automati-
              cally; it must be  manually  reset  between  multiple  calls  to
              ggeettooppttss within the same shell invocation if a new set of parame-
              ters is to be used.

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

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

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

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

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

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

       hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e]
              For each _n_a_m_e, the full file name of the command  is  determined
              by searching the directories in $$PPAATTHH and remembered.  If the --pp
              option is supplied, no path search is performed, and _f_i_l_e_n_a_m_e is
              used as the full file name of the command.  The --rr option causes
              the shell to forget all remembered  locations.   The  --dd  option
              causes the shell to forget the remembered location of each _n_a_m_e.
              If the --tt option is supplied, the full pathname  to  which  each
              _n_a_m_e  corresponds  is  printed.   If multiple _n_a_m_e arguments are
              supplied with --tt, the _n_a_m_e is printed  before  the  hashed  full
              pathname.  The --ll option causes output to be displayed in a for-
              mat that may be reused as input.  If no arguments are given,  or
              if only --ll is supplied, information about remembered commands is
              printed.  The return status is true unless a _n_a_m_e is  not  found
              or an invalid option is supplied.

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

       hhiissttoorryy [[_n]]
       hhiissttoorryy --cc
       hhiissttoorryy --dd _o_f_f_s_e_t
       hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e]
       hhiissttoorryy --pp _a_r_g [_a_r_g _._._.]
       hhiissttoorryy --ss _a_r_g [_a_r_g _._._.]
              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 HHIISSTTTTIIMMEE--
              FFOORRMMAATT is set and not null, it is used as a  format  string  for
              _s_t_r_f_t_i_m_e(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 _f_i_l_e_n_a_m_e is
              supplied, it is used as the name of the history  file;  if  not,
              the  value  of HHIISSTTFFIILLEE is used.  Options, if supplied, have the
              following meanings:
              --cc     Clear the history list by deleting all the entries.
              --dd _o_f_f_s_e_t
                     Delete the history entry at position _o_f_f_s_e_t.
              --aa     Append the ``new'' history lines (history  lines  entered
                     since  the  beginning of the current bbaasshh session) to the
                     history file.
              --nn     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 bbaasshh session.
              --rr     Read the contents of the history file and use them as the
                     current history.
              --ww     Write the current history to the history file,  overwrit-
                     ing the history file's contents.
              --pp     Perform  history  substitution  on the following _a_r_g_s and
                     display the result on  the  standard  output.   Does  not
                     store  the results in the history list.  Each _a_r_g must be
                     quoted to disable normal history expansion.
              --ss     Store the _a_r_g_s in the history list  as  a  single  entry.
                     The  last  command  in the history list is removed before
                     the _a_r_g_s are added.

              If the HHIISSTTTTIIMMEEFFOORRMMAATT 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 _o_f_f_s_e_t is sup-
              plied as an argument to --dd, or the history expansion supplied as
              an argument to --pp fails.

       jjoobbss [--llnnpprrss] [ _j_o_b_s_p_e_c ... ]
       jjoobbss --xx _c_o_m_m_a_n_d [ _a_r_g_s ... ]
              The first form lists the active jobs.  The options have the fol-
              lowing meanings:
              --ll     List process IDs in addition to the normal information.
              --pp     List only the process  ID  of  the  job's  process  group
                     leader.
              --nn     Display  information  only  about  jobs that have changed
                     status since the user was last notified of their  status.
              --rr     Restrict output to running jobs.
              --ss     Restrict output to stopped jobs.

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

              If the --xx option is supplied, jjoobbss replaces any _j_o_b_s_p_e_c found in
              _c_o_m_m_a_n_d or _a_r_g_s with the corresponding  process  group  ID,  and
              executes _c_o_m_m_a_n_d passing it _a_r_g_s, returning its exit status.

       kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] [_p_i_d | _j_o_b_s_p_e_c] ...
       kkiillll --ll [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s]
              Send  the  signal  named  by  _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes
              named by _p_i_d or _j_o_b_s_p_e_c.  _s_i_g_s_p_e_c is either  a  case-insensitive
              signal  name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or
              a signal number; _s_i_g_n_u_m is a signal number.  If _s_i_g_s_p_e_c  is  not
              present,  then  SSIIGGTTEERRMM is assumed.  An argument of --ll lists the
              signal names.  If any arguments are supplied when --ll  is  given,
              the  names  of  the  signals  corresponding to the arguments are
              listed, and the return status is 0.  The _e_x_i_t___s_t_a_t_u_s argument to
              --ll  is  a  number  specifying either a signal number or the exit
              status of a process terminated by a signal.  kkiillll  returns  true
              if  at  least  one  signal was successfully sent, or false if an
              error occurs or an invalid option is encountered.

       lleett _a_r_g [_a_r_g ...]
              Each _a_r_g is an arithmetic expression to be evaluated (see AARRIITTHH--
              MMEETTIICC  EEVVAALLUUAATTIIOONN  above).   If the last _a_r_g evaluates to 0, lleett
              returns 1; 0 is returned otherwise.

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

       llooggoouutt Exit a login shell.

       mmaappffiillee [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu  _f_d]  [--CC  _c_a_l_l_b_a_c_k]
       [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y]
       rreeaaddaarrrraayy [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC  _c_a_l_l_b_a_c_k]
       [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y]
              Read lines from the standard input into the indexed array  vari-
              able  _a_r_r_a_y, or from file descriptor _f_d if the --uu option is sup-
              plied.  The variable MMAAPPFFIILLEE is the default _a_r_r_a_y.  Options,  if
              supplied, have the following meanings:
              --nn     Copy  at  most _c_o_u_n_t lines.  If _c_o_u_n_t is 0, all lines are
                     copied.
              --OO     Begin assigning to _a_r_r_a_y at index  _o_r_i_g_i_n.   The  default
                     index is 0.
              --ss     Discard the first _c_o_u_n_t lines read.
              --tt     Remove a trailing newline from each line read.
              --uu     Read  lines  from file descriptor _f_d instead of the stan-
                     dard input.
              --CC     Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read.   The
                     --cc option specifies _q_u_a_n_t_u_m.
              --cc     Specify  the  number  of  lines read between each call to
                     _c_a_l_l_b_a_c_k.

              If --CC is specified without --cc,  the  default  quantum  is  5000.
              When _c_a_l_l_b_a_c_k is evaluated, it is supplied the index of the next
              array element to be assigned as an additional  argument.   _c_a_l_l_-
              _b_a_c_k  is  evaluated  after the line is read but before the array
              element is assigned.

              If not supplied with an  explicit  origin,  mmaappffiillee  will  clear
              _a_r_r_a_y before assigning to it.

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

       ppooppdd [-nn] [+_n] [-_n]
              Removes  entries  from  the directory stack.  With no arguments,
              removes the top directory from the stack, and performs a  ccdd  to
              the new top directory.  Arguments, if supplied, have the follow-
              ing meanings:
              --nn     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  ddiirrss, 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 ddiirrss, starting with zero.  For  example:  ``popd
                     -0''  removes the last directory, ``popd -1'' the next to
                     last.

              If the ppooppdd command is successful, a ddiirrss is performed as  well,
              and  the  return  status is 0.  ppooppdd 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.

       pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s]
              Write the formatted _a_r_g_u_m_e_n_t_s to the standard output  under  the
              control  of  the _f_o_r_m_a_t.  The _f_o_r_m_a_t is a character string which
              contains three types of objects:  plain  characters,  which  are
              simply  copied  to  standard output, character escape sequences,
              which are converted and copied to the standard output, and  for-
              mat  specifications,  each  of which causes printing of the next
              successive _a_r_g_u_m_e_n_t.  In addition to the standard _p_r_i_n_t_f(1) for-
              mats,  %%bb  causes pprriinnttff to expand backslash escape sequences in
              the corresponding _a_r_g_u_m_e_n_t (except that  \\cc  terminates  output,
              backslashes in \\'', \\"", and \\?? are not removed, and octal escapes
              beginning with \\00 may contain up to four digits), and %%qq  causes
              pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a format that can
              be reused as shell input.

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

              The  _f_o_r_m_a_t  is  reused as necessary to consume all of the _a_r_g_u_-
              _m_e_n_t_s.  If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s 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.

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

              If the ppuusshhdd command is successful, a ddiirrss is performed as well.
              If  the first form is used, ppuusshhdd returns 0 unless the cd to _d_i_r
              fails.  With the second form, ppuusshhdd 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.

       ppwwdd [--LLPP]
              Print  the  absolute  pathname of the current working directory.
              The pathname printed contains no symbolic links if the --PP option
              is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command
              is enabled.  If the --LL 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.

       rreeaadd [--eerrss] [--aa _a_n_a_m_e] [--dd _d_e_l_i_m] [--ii _t_e_x_t] [--nn _n_c_h_a_r_s] [--NN _n_c_h_a_r_s] [--pp
       _p_r_o_m_p_t] [--tt _t_i_m_e_o_u_t] [--uu _f_d] [_n_a_m_e ...]
              One  line  is  read  from  the  standard input, or from the file
              descriptor _f_d supplied as an argument to the --uu option, and  the
              first word is assigned to the first _n_a_m_e, the second word to the
              second _n_a_m_e, and so on, with leftover words and their  interven-
              ing  separators  assigned  to the last _n_a_m_e.  If there are fewer
              words read from the input stream than names, the remaining names
              are  assigned  empty  values.  The characters in IIFFSS are used to
              split the line into words.  The backslash character (\\)  may  be
              used  to  remove any special meaning for the next character read
              and for line continuation.  Options, if supplied, have the  fol-
              lowing meanings:
              --aa _a_n_a_m_e
                     The words are assigned to sequential indices of the array
                     variable _a_n_a_m_e, starting at 0.  _a_n_a_m_e is unset before any
                     new  values  are  assigned.   Other  _n_a_m_e  arguments  are
                     ignored.
              --dd _d_e_l_i_m
                     The first character of _d_e_l_i_m is  used  to  terminate  the
                     input line, rather than newline.
              --ee     If the standard input is coming from a terminal, rreeaaddlliinnee
                     (see RREEAADDLLIINNEE above) is used to obtain the  line.   Read-
                     line  uses  the  current (or default, if line editing was
                     not previously active) editing settings.
              --ii _t_e_x_t
                     If rreeaaddlliinnee is being used  to  read  the  line,  _t_e_x_t  is
                     placed into the editing buffer before editing begins.
              --nn _n_c_h_a_r_s
                     rreeaadd  returns after reading _n_c_h_a_r_s characters rather than
                     waiting for a complete line of input, but honor a  delim-
                     iter  if fewer than _n_c_h_a_r_s characters are read before the
                     delimiter.
              --NN _n_c_h_a_r_s
                     rreeaadd returns  after  reading  exactly  _n_c_h_a_r_s  characters
                     rather  than waiting for a complete line of input, unless
                     EOF is encountered or rreeaadd times out.  Delimiter  charac-
                     ters  encountered  in the input are not treated specially
                     and do not cause rreeaadd to return until  _n_c_h_a_r_s  characters
                     are read.
              --pp _p_r_o_m_p_t
                     Display _p_r_o_m_p_t 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.
              --rr     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.
              --ss     Silent mode.  If input is coming from a terminal, charac-
                     ters are not echoed.
              --tt _t_i_m_e_o_u_t
                     Cause  rreeaadd  to time out and return failure if a complete
                     line of input is not read within _t_i_m_e_o_u_t seconds.   _t_i_m_e_-
                     _o_u_t  may  be  a  decimal number with a fractional portion
                     following the decimal point.  This option is only  effec-
                     tive  if  rreeaadd is reading input from a terminal, pipe, or
                     other special file; it has no effect  when  reading  from
                     regular  files.  If _t_i_m_e_o_u_t is 0, rreeaadd returns success if
                     input is available  on  the  specified  file  descriptor,
                     failure  otherwise.   The exit status is greater than 128
                     if the timeout is exceeded.
              --uu _f_d  Read input from file descriptor _f_d.

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

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

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

       sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n] [_a_r_g ...]
       sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n] [_a_r_g ...]
              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 _p_o_s_i_x _m_o_d_e, 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:
              --aa      Automatically  mark  variables  and  functions which are
                      modified or created for export  to  the  environment  of
                      subsequent commands.
              --bb      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.
              --ee      Exit  immediately  if a _p_i_p_e_l_i_n_e (which may consist of a
                      single _s_i_m_p_l_e _c_o_m_m_a_n_d),  a _s_u_b_s_h_e_l_l command enclosed  in
                      parentheses,  or one of the commands executed as part of
                      a command list enclosed by  braces  (see  SSHHEELLLL  GGRRAAMMMMAARR
                      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  wwhhiillee or uunnttiill keyword,
                      part of the test  following  the  iiff  or  eelliiff  reserved
                      words,  part  of any command executed in a &&&& or |||| list
                      except the command following the final  &&&&  or  ||||,  any
                      command  in a pipeline but the last, or if the command's
                      return value is being inverted with !!.  A trap  on  EERRRR,
                      if set, is executed before the shell exits.  This option
                      applies to the shell environment and each subshell envi-
                      ronment  separately  (see  CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT
                      above), and may cause subshells to exit before executing
                      all the commands in the subshell.
              --ff      Disable pathname expansion.
              --hh      Remember  the location of commands as they are looked up
                      for execution.  This is enabled by default.
              --kk      All arguments in the form of assignment  statements  are
                      placed  in the environment for a command, not just those
                      that precede the command name.
              --mm      Monitor mode.  Job control is enabled.  This  option  is
                      on  by  default  for  interactive shells on systems that
                      support it (see JJOOBB  CCOONNTTRROOLL  above).   Background  pro-
                      cesses  run  in a separate process group and a line con-
                      taining their exit status is printed upon their  comple-
                      tion.
              --nn      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.
              --oo _o_p_t_i_o_n_-_n_a_m_e
                      The _o_p_t_i_o_n_-_n_a_m_e can be one of the following:
                      aalllleexxppoorrtt
                              Same as --aa.
                      bbrraacceeeexxppaanndd
                              Same as --BB.
                      eemmaaccss   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 ----nnooeeddiittiinngg option.  This also  affects  the
                              editing interface used for rreeaadd --ee.
                      eerrrreexxiitt Same as --ee.
                      eerrrrttrraaccee
                              Same as --EE.
                      ffuunnccttrraaccee
                              Same as --TT.
                      hhaasshhaallll Same as --hh.
                      hhiisstteexxppaanndd
                              Same as --HH.
                      hhiissttoorryy Enable command history, as described above under
                              HHIISSTTOORRYY.  This option is on by default in inter-
                              active shells.
                      iiggnnoorreeeeooff
                              The   effect   is   as   if  the  shell  command
                              ``IGNOREEOF=10'' had been  executed  (see  SShheellll
                              VVaarriiaabblleess above).
                      kkeeyywwoorrdd Same as --kk.
                      mmoonniittoorr Same as --mm.
                      nnoocclloobbbbeerr
                              Same as --CC.
                      nnooeexxeecc  Same as --nn.
                      nnoogglloobb  Same as --ff.
                      nnoolloogg   Currently ignored.
                      nnoottiiffyy  Same as --bb.
                      nnoouunnsseett Same as --uu.
                      oonneeccmmdd  Same as --tt.
                      pphhyyssiiccaall
                              Same as --PP.
                      ppiippeeffaaiill
                              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.
                      ppoossiixx   Change  the  behavior  of bbaasshh where the default
                              operation differs from  the  POSIX  standard  to
                              match the standard (_p_o_s_i_x _m_o_d_e).
                      pprriivviilleeggeedd
                              Same as --pp.
                      vveerrbboossee Same as --vv.
                      vvii      Use  a  vi-style command line editing interface.
                              This also affects the editing interface used for
                              rreeaadd --ee.
                      xxttrraaccee  Same as --xx.
                      If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, the values of the
                      current options are printed.  If ++oo is supplied with  no
                      _o_p_t_i_o_n_-_n_a_m_e,  a  series  of sseett commands to recreate the
                      current option settings is  displayed  on  the  standard
                      output.
              --pp      Turn  on  _p_r_i_v_i_l_e_g_e_d  mode.   In this mode, the $$EENNVV and
                      $$BBAASSHH__EENNVV files are not processed, shell  functions  are
                      not  inherited  from the environment, and the SSHHEELLLLOOPPTTSS,
                      BBAASSHHOOPPTTSS, CCDDPPAATTHH,  and  GGLLOOBBIIGGNNOORREE  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 --pp option is not sup-
                      plied, these actions are taken and the effective user id
                      is  set  to  the real user id.  If the --pp 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.
              --tt      Exit after reading and executing one command.
              --uu      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.
              --vv      Print shell input lines as they are read.
              --xx      After  expanding  each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee
                      command, sseelleecctt command, or arithmetic ffoorr command, dis-
                      play  the expanded value of PPSS44, followed by the command
                      and its expanded arguments or associated word list.
              --BB      The shell performs brace expansion (see BBrraaccee  EExxppaannssiioonn
                      above).  This is on by default.
              --CC      If  set,  bbaasshh  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 >>.
              --EE      If set, any trap on EERRRR is inherited by shell functions,
                      command  substitutions,  and commands executed in a sub-
                      shell environment.  The EERRRR trap is normally not  inher-
                      ited in such cases.
              --HH      Enable !!  style history substitution.  This option is on
                      by default when the shell is interactive.
              --PP      If set, the shell does not follow  symbolic  links  when
                      executing  commands  such  as ccdd that change the current
                      working  directory.   It  uses  the  physical  directory
                      structure instead.  By default, bbaasshh follows the logical
                      chain of  directories  when  performing  commands  which
                      change the current directory.
              --TT      If  set,  any traps on DDEEBBUUGG and RREETTUURRNN are inherited by
                      shell functions,  command  substitutions,  and  commands
                      executed  in  a  subshell  environment.   The  DDEEBBUUGG and
                      RREETTUURRNN 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 _a_r_gs, even if  some  of  them  begin
                      with a --.
              --       Signal  the  end of options, cause all remaining _a_r_gs to
                      be assigned to the positional parameters.  The --xx and --vv
                      options are turned off.  If there are no _a_r_gs, 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.

       sshhiifftt [_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.

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

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

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

              The list of sshhoopptt options is:

              aauuttooccdd  If  set,  a command name that is the name of a directory
                      is executed as if it were the argument to  the  ccdd  com-
                      mand.  This option is only used by interactive shells.
              ccddaabbllee__vvaarrss
                      If  set,  an  argument to the ccdd builtin command that is
                      not a directory is assumed to be the name of a  variable
                      whose value is the directory to change to.
              ccddssppeellll If set, minor errors in the spelling of a directory com-
                      ponent in a ccdd command will be  corrected.   The  errors
                      checked for are transposed characters, a missing charac-
                      ter, and one character too many.   If  a  correction  is
                      found,  the corrected file name is printed, and the com-
                      mand proceeds.  This option is only used by  interactive
                      shells.
              cchheecckkhhaasshh
                      If set, bbaasshh 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.
              cchheecckkjjoobbss
                      If set, bbaasshh 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 JJOOBB CCOONNTTRROOLL above).   The  shell  always  postpones
                      exiting if any jobs are stopped.
              cchheecckkwwiinnssiizzee
                      If  set,  bbaasshh checks the window size after each command
                      and, if necessary, updates the values of LLIINNEESS and  CCOOLL--
                      UUMMNNSS.
              ccmmddhhiisstt If  set,  bbaasshh attempts to save all lines of a multiple-
                      line command in the same  history  entry.   This  allows
                      easy re-editing of multi-line commands.
              ccoommppaatt3311
                      If set, bbaasshh changes its behavior to that of version 3.1
                      with respect to quoted arguments to the conditional com-
                      mand's =~ operator.
              ccoommppaatt3322
                      If set, bbaasshh changes its behavior to that of version 3.2
                      with respect to locale-specific string  comparison  when
                      using the conditional command's < and > operators.
              ccoommppaatt4400
                      If set, bbaasshh changes its behavior to that of version 4.0
                      with respect to locale-specific string  comparison  when
                      using  the  conditional  command's < and > operators and
                      the effect of interrupting a command list.
              ddiirrssppeellll
                      If set, bbaasshh attempts spelling correction  on  directory
                      names  during word completion if the directory name ini-
                      tially supplied does not exist.
              ddoottgglloobb If set, bbaasshh includes filenames beginning with a `.'  in
                      the results of pathname expansion.
              eexxeeccffaaiill
                      If set, a non-interactive shell will not exit if it can-
                      not execute the file specified as  an  argument  to  the
                      eexxeecc  builtin  command.   An  interactive shell does not
                      exit if eexxeecc fails.
              eexxppaanndd__aalliiaasseess
                      If set, aliases are expanded as  described  above  under
                      AALLIIAASSEESS.  This option is enabled by default for interac-
                      tive shells.
              eexxttddeebbuugg
                      If set,  behavior  intended  for  use  by  debuggers  is
                      enabled:
                      11..     The --FF option to the ddeeccllaarree 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 DDEEBBUUGG trap returns a
                             non-zero value, the next command is  skipped  and
                             not executed.
                      33..     If  the  command  run by the DDEEBBUUGG 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 ssoouurrccee  builtins),  a  call  to
                             rreettuurrnn is simulated.
                      44..     BBAASSHH__AARRGGCC  and BBAASSHH__AARRGGVV are updated as described
                             in their descriptions above.
                      55..     Function tracing is enabled:   command  substitu-
                             tion, shell functions, and subshells invoked with
                             (( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps.
                      66..     Error tracing is enabled:  command  substitution,
                             shell  functions,  and  subshells  invoked with ((
                             _c_o_m_m_a_n_d )) inherit the EERRRROORR trap.
              eexxttgglloobb If set, the extended pattern matching features described
                      above under PPaatthhnnaammee EExxppaannssiioonn are enabled.
              eexxttqquuoottee
                      If  set,  $$'_s_t_r_i_n_g'  and  $$"_s_t_r_i_n_g" quoting is performed
                      within  $${{_p_a_r_a_m_e_t_e_r}}  expansions  enclosed   in   double
                      quotes.  This option is enabled by default.
              ffaaiillgglloobb
                      If  set,  patterns  which fail to match filenames during
                      pathname expansion result in an expansion error.
              ffoorrccee__ffiiggnnoorree
                      If set, the suffixes  specified  by  the  FFIIGGNNOORREE  shell
                      variable  cause words to be ignored when performing word
                      completion even if the ignored words are the only possi-
                      ble  completions.   See  SSHHEELLLL  VVAARRIIAABBLLEESS  above  for  a
                      description of  FFIIGGNNOORREE.   This  option  is  enabled  by
                      default.
              gglloobbssttaarr
                      If set, the pattern **** used in a pathname expansion con-
                      text will match a files and zero or more directories and
                      subdirectories.  If the pattern is followed by a //, only
                      directories and subdirectories match.
              ggnnuu__eerrrrffmmtt
                      If set, shell error messages are written in the standard
                      GNU error message format.
              hhiissttaappppeenndd
                      If  set,  the history list is appended to the file named
                      by the value of the HHIISSTTFFIILLEE  variable  when  the  shell
                      exits, rather than overwriting the file.
              hhiissttrreeeeddiitt
                      If  set, and rreeaaddlliinnee is being used, a user is given the
                      opportunity to re-edit a failed history substitution.
              hhiissttvveerriiffyy
                      If set, and rreeaaddlliinnee 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 rreeaaddlliinnee editing buffer, allowing further modi-
                      fication.
              hhoossttccoommpplleettee
                      If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to
                      perform  hostname  completion when a word containing a @@
                      is  being  completed  (see  CCoommpplleettiinngg  under   RREEAADDLLIINNEE
                      above).  This is enabled by default.
              hhuuppoonneexxiitt
                      If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter-
                      active login shell exits.
              iinntteerraaccttiivvee__ccoommmmeennttss
                      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  CCOOMMMMEENNTTSS  above).   This
                      option is enabled by default.
              lliitthhiisstt If  set,  and  the ccmmddhhiisstt option is enabled, multi-line
                      commands are saved to the history with embedded newlines
                      rather than using semicolon separators where possible.
              llooggiinn__sshheellll
                      The  shell  sets this option if it is started as a login
                      shell (see IINNVVOOCCAATTIIOONN above).   The  value  may  not  be
                      changed.
              mmaaiillwwaarrnn
                      If  set,  and  a file that bbaasshh is checking for mail has
                      been accessed since the last time it  was  checked,  the
                      message  ``The  mail in _m_a_i_l_f_i_l_e has been read'' is dis-
                      played.
              nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn
                      If set, and  rreeaaddlliinnee  is  being  used,  bbaasshh  will  not
                      attempt to search the PPAATTHH for possible completions when
                      completion is attempted on an empty line.
              nnooccaasseegglloobb
                      If set, bbaasshh matches  filenames  in  a  case-insensitive
                      fashion when performing pathname expansion (see PPaatthhnnaammee
                      EExxppaannssiioonn above).
              nnooccaasseemmaattcchh
                      If set, bbaasshh  matches  patterns  in  a  case-insensitive
                      fashion when performing matching while executing ccaassee or
                      [[[[ conditional commands.
              nnuullllgglloobb
                      If set, bbaasshh allows patterns which match no  files  (see
                      PPaatthhnnaammee  EExxppaannssiioonn  above)  to expand to a null string,
                      rather than themselves.
              pprrooggccoommpp
                      If set, the programmable completion facilities (see PPrroo--
                      ggrraammmmaabbllee CCoommpplleettiioonn above) are enabled.  This option is
                      enabled by default.
              pprroommppttvvaarrss
                      If set, prompt strings undergo parameter expansion, com-
                      mand   substitution,  arithmetic  expansion,  and  quote
                      removal after being expanded as described  in  PPRROOMMPPTTIINNGG
                      above.  This option is enabled by default.
              rreessttrriicctteedd__sshheellll
                      The   shell  sets  this  option  if  it  is  started  in
                      restricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL 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.
              sshhiifftt__vveerrbboossee
                      If  set,  the sshhiifftt builtin prints an error message when
                      the shift count exceeds the number of positional parame-
                      ters.
              ssoouurrcceeppaatthh
                      If set, the ssoouurrccee (..) builtin uses the value of PPAATTHH to
                      find the directory containing the file  supplied  as  an
                      argument.  This option is enabled by default.
              xxppgg__eecchhoo
                      If   set,  the  eecchhoo  builtin  expands  backslash-escape
                      sequences by default.
       ssuussppeenndd [--ff]
              Suspend the execution of this shell until it receives a  SSIIGGCCOONNTT
              signal.  A login shell cannot be suspended; the --ff 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 --ff is not sup-
              plied, or if job control is not enabled.
       tteesstt _e_x_p_r
       [[ _e_x_p_r ]]
              Return a status of 0 or 1 depending on  the  evaluation  of  the
              conditional  expression _e_x_p_r.  Each operator and operand must be
              a separate argument.  Expressions are composed of the  primaries
              described  above  under  CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS.  tteesstt 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.
              !! _e_x_p_r True if _e_x_p_r is false.
              (( _e_x_p_r ))
                     Returns  the value of _e_x_p_r.  This may be used to override
                     the normal precedence of operators.
              _e_x_p_r_1 -aa _e_x_p_r_2
                     True if both _e_x_p_r_1 and _e_x_p_r_2 are true.
              _e_x_p_r_1 -oo _e_x_p_r_2
                     True if either _e_x_p_r_1 or _e_x_p_r_2 is true.

              tteesstt 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  CCOONNDDIITTIIOONNAALL  EEXXPPRREESSSSIIOONNSS, the expression is
                     true if the unary test is true.  If the first argument is
                     not a valid unary conditional operator, the expression is
                     false.
              3 arguments
                     If the second argument is one of the  binary  conditional
                     operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the
                     result of the expression is the result of the binary test
                     using  the first and third arguments as operands.  The --aa
                     and --oo 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.

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

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

              If  a  _s_i_g_s_p_e_c  is  EEXXIITT (0) the command _a_r_g is executed on exit
              from the shell.  If a _s_i_g_s_p_e_c is DDEEBBUUGG, the command _a_r_g is  exe-
              cuted  before  every  _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command,
              _s_e_l_e_c_t command, every arithmetic _f_o_r  command,  and  before  the
              first  command  executes  in a shell function (see SSHHEELLLL GGRRAAMMMMAARR
              above).  Refer to the description of the eexxttddeebbuugg option to  the
              sshhoopptt builtin for details of its effect on the DDEEBBUUGG trap.  If a
              _s_i_g_s_p_e_c is RREETTUURRNN, the command _a_r_g is executed each time a shell
              function or a script executed with the .. or ssoouurrccee builtins fin-
              ishes executing.

              If a _s_i_g_s_p_e_c is EERRRR, the command _a_r_g is executed whenever a sim-
              ple command has a non-zero exit status, subject to the following
              conditions.  The EERRRR trap is not executed if the failed  command
              is  part  of  the  command list immediately following a wwhhiillee or
              uunnttiill keyword, part of the test in an _i_f statement,  part  of  a
              command  executed in a &&&& or |||| list, or if the command's return
              value is being inverted via !!.  These are  the  same  conditions
              obeyed by the eerrrreexxiitt 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  _s_i_g_s_p_e_c  is
              invalid; otherwise ttrraapp returns true.

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

       uulliimmiitt [--HHSSTTaabbccddeeffiillmmnnppqqrrssttuuvvxx [_l_i_m_i_t]]
              Provides  control  over the resources available to the shell and
              to processes started by it, on systems that allow such  control.
              The --HH and --SS 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 --HH nor --SS is  speci-
              fied, both the soft and hard limits are set.  The value of _l_i_m_i_t
              can be a number in the unit specified for the resource or one of
              the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, which stand for the
              current hard limit,  the  current  soft  limit,  and  no  limit,
              respectively.   If  _l_i_m_i_t  is  omitted, the current value of the
              soft limit of the resource is printed, unless the --HH  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:
              --aa     All current limits are reported
              --bb     The maximum socket buffer size
              --cc     The maximum size of core files created
              --dd     The maximum size of a process's data segment
              --ee     The maximum scheduling priority ("nice")
              --ff     The  maximum  size  of files written by the shell and its
                     children
              --ii     The maximum number of pending signals
              --ll     The maximum size that may be locked into memory
              --mm     The maximum resident set size (many systems do not  honor
                     this limit)
              --nn     The maximum number of open file descriptors (most systems
                     do not allow this value to be set)
              --pp     The pipe size in 512-byte blocks (this may not be set)
              --qq     The maximum number of bytes in POSIX message queues
              --rr     The maximum real-time scheduling priority
              --ss     The maximum stack size
              --tt     The maximum amount of cpu time in seconds
              --uu     The maximum number of processes  available  to  a  single
                     user
              --vv     The  maximum  amount  of  virtual memory available to the
                     shell
              --xx     The maximum number of file locks
              --TT     The maximum number of threads

              If _l_i_m_i_t is given, it is the new value of the specified resource
              (the --aa option is display only).  If no option is given, then --ff
              is assumed.  Values are in 1024-byte increments, except for  --tt,
              which  is  in seconds, --pp, which is in units of 512-byte blocks,
              and --TT, --bb, --nn, and --uu, which are unscaled values.   The  return
              status is 0 unless an invalid option or argument is supplied, or
              an error occurs while setting a new limit.

       uummaasskk [--pp] [--SS] [_m_o_d_e]
              The user file-creation mask is set to _m_o_d_e.  If _m_o_d_e 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
              _c_h_m_o_d(1).   If _m_o_d_e is omitted, the current value of the mask is
              printed.  The --SS option causes the mask to be  printed  in  sym-
              bolic  form;  the  default output is an octal number.  If the --pp
              option is supplied, and _m_o_d_e 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 _m_o_d_e  argument  was  supplied,
              and false otherwise.

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

       uunnsseett [-ffvv] [_n_a_m_e ...]
              For  each  _n_a_m_e,  remove the corresponding variable or function.
              If no options are supplied, or the --vv option is given, each _n_a_m_e
              refers  to  a  shell  variable.   Read-only variables may not be
              unset.  If --ff is specified, each _n_a_m_e refers to  a  shell  func-
              tion,  and the function definition is removed.  Each unset vari-
              able or function is removed from the environment passed to  sub-
              sequent  commands.   If any of CCOOMMPP__WWOORRDDBBRREEAAKKSS, RRAANNDDOOMM, SSEECCOONNDDSS,
              LLIINNEENNOO, HHIISSTTCCMMDD, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, or DDIIRRSSTTAACCKK are  unset,  they
              lose  their  special  properties,  even if they are subsequently
              reset.  The exit status is true unless a _n_a_m_e is readonly.

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

SSEEEE AALLSSOO
       bash(1), sh(1)



GNU Bash-4.0                      2004 Apr 20                 BASH_BUILTINS(1)