BASH(1)                                                                BASH(1)



NNAAMMEE
       bash - GNU Bourne-Again SHell

SSYYNNOOPPSSIISS
       bbaasshh [options] [command_string | file]

CCOOPPYYRRIIGGHHTT
       Bash is Copyright (C) 1989-2013 by the Free Software Foundation, Inc.

DDEESSCCRRIIPPTTIIOONN
       BBaasshh  is  an  sshh-compatible  command language interpreter that executes
       commands read from the standard input or from a file.  BBaasshh also incor-
       porates useful features from the _K_o_r_n and _C shells (kksshh and ccsshh).

       BBaasshh  is  intended  to  be a conformant implementation of the Shell and
       Utilities portion  of  the  IEEE  POSIX  specification  (IEEE  Standard
       1003.1).  BBaasshh can be configured to be POSIX-conformant by default.

OOPPTTIIOONNSS
       All  of  the  single-character shell options documented in the descrip-
       tion of the sseett builtin command can be used as options when  the  shell
       is invoked.  In addition, bbaasshh interprets the following options when it
       is invoked:

       --cc        If the --cc option is present, then commands are read from  the
                 first non-option argument _c_o_m_m_a_n_d___s_t_r_i_n_g.  If there are argu-
                 ments after the _c_o_m_m_a_n_d___s_t_r_i_n_g,  they  are  assigned  to  the
                 positional parameters, starting with $$00.
       --ii        If the --ii option is present, the shell is _i_n_t_e_r_a_c_t_i_v_e.
       --ll        Make bbaasshh act as if it had been invoked as a login shell (see
                 IINNVVOOCCAATTIIOONN below).
       --rr        If the --rr option is present,  the  shell  becomes  _r_e_s_t_r_i_c_t_e_d
                 (see RREESSTTRRIICCTTEEDD SSHHEELLLL below).
       --ss        If  the --ss option is present, or if no arguments remain after
                 option processing, then commands are read from  the  standard
                 input.   This  option  allows the positional parameters to be
                 set when invoking an interactive shell.
       --DD        A list of all double-quoted strings preceded by $$ is  printed
                 on  the standard output.  These are the strings that are sub-
                 ject to language translation when the current locale is not CC
                 or  PPOOSSIIXX.   This  implies the --nn option; no commands will be
                 executed.
       [[--++]]OO [[_s_h_o_p_t___o_p_t_i_o_n]]
                 _s_h_o_p_t___o_p_t_i_o_n is one of the  shell  options  accepted  by  the
                 sshhoopptt   builtin  (see  SSHHEELLLL  BBUUIILLTTIINN  CCOOMMMMAANNDDSS  below).   If
                 _s_h_o_p_t___o_p_t_i_o_n is present, --OO sets the value of that option; ++OO
                 unsets  it.   If  _s_h_o_p_t___o_p_t_i_o_n is not supplied, the names and
                 values of the shell options accepted by sshhoopptt are printed  on
                 the  standard  output.   If  the invocation option is ++OO, the
                 output is displayed in a format that may be reused as  input.
       ----        A  ----  signals the end of options and disables further option
                 processing.  Any arguments after the ---- are treated as  file-
                 names and arguments.  An argument of -- is equivalent to ----.

       BBaasshh  also  interprets  a  number  of  multi-character  options.  These
       options must appear on the command  line  before  the  single-character
       options to be recognized.

       ----ddeebbuuggggeerr
              Arrange for the debugger profile to be executed before the shell
              starts.  Turns on extended debugging mode (see  the  description
              of the eexxttddeebbuugg option to the sshhoopptt builtin below).
       ----dduummpp--ppoo--ssttrriinnggss
              Equivalent  to --DD, but the output is in the GNU _g_e_t_t_e_x_t ppoo (por-
              table object) file format.
       ----dduummpp--ssttrriinnggss
              Equivalent to --DD.
       ----hheellpp Display a usage message on standard  output  and  exit  success-
              fully.
       ----iinniitt--ffiillee _f_i_l_e
       ----rrccffiillee _f_i_l_e
              Execute commands from _f_i_l_e instead of the standard personal ini-
              tialization file _~_/_._b_a_s_h_r_c if  the  shell  is  interactive  (see
              IINNVVOOCCAATTIIOONN below).

       ----llooggiinn
              Equivalent to --ll.

       ----nnooeeddiittiinngg
              Do  not  use the GNU rreeaaddlliinnee library to read command lines when
              the shell is interactive.

       ----nnoopprrooffiillee
              Do not read either the system-wide startup file _/_e_t_c_/_p_r_o_f_i_l_e  or
              any   of  the  personal  initialization  files  _~_/_._b_a_s_h___p_r_o_f_i_l_e,
              _~_/_._b_a_s_h___l_o_g_i_n, or _~_/_._p_r_o_f_i_l_e.   By  default,  bbaasshh  reads  these
              files  when  it  is  invoked  as  a  login shell (see IINNVVOOCCAATTIIOONN
              below).

       ----nnoorrcc Do  not  read  and  execute  the  personal  initialization  file
              _~_/_._b_a_s_h_r_c  if  the  shell  is interactive.  This option is on by
              default if the shell is invoked as sshh.

       ----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).  See
              SSEEEE AALLSSOO below for a reference to a document  that  details  how
              posix mode affects bash's behavior.

       ----rreessttrriicctteedd
              The shell becomes restricted (see RREESSTTRRIICCTTEEDD SSHHEELLLL below).

       ----vveerrbboossee
              Equivalent to  --vv.

       ----vveerrssiioonn
              Show  version information for this instance of bbaasshh on the stan-
              dard output and exit successfully.

AARRGGUUMMEENNTTSS
       If arguments remain after option processing, and neither the --cc nor the
       --ss  option  has  been supplied, the first argument is assumed to be the
       name of a file containing shell commands.  If bbaasshh is invoked  in  this
       fashion,  $$00 is set to the name of the file, and the positional parame-
       ters are set to the remaining arguments.  BBaasshh reads and executes  com-
       mands  from this file, then exits.  BBaasshh's exit status is the exit sta-
       tus of the last command executed in the script.   If  no  commands  are
       executed,  the  exit status is 0.  An attempt is first made to open the
       file in the current directory, and, if no file is found, then the shell
       searches the directories in PPAATTHH for the script.

IINNVVOOCCAATTIIOONN
       A  _l_o_g_i_n _s_h_e_l_l is one whose first character of argument zero is a --, or
       one started with the ----llooggiinn option.

       An _i_n_t_e_r_a_c_t_i_v_e shell is one started without  non-option  arguments  and
       without the --cc option whose standard input and error are both connected
       to terminals (as determined by _i_s_a_t_t_y(3)), or one started with  the  --ii
       option.   PPSS11 is set and $$-- includes ii if bbaasshh is interactive, allowing
       a shell script or a startup file to test this state.

       The following paragraphs describe how bbaasshh executes its startup  files.
       If  any  of  the files exist but cannot be read, bbaasshh reports an error.
       Tildes are expanded in filenames as described below under TTiillddee  EExxppaann--
       ssiioonn in the EEXXPPAANNSSIIOONN section.

       When  bbaasshh is invoked as an interactive login shell, or as a non-inter-
       active shell with the ----llooggiinn option, it first reads and executes  com-
       mands  from  the file _/_e_t_c_/_p_r_o_f_i_l_e, if that file exists.  After reading
       that file, it looks for _~_/_._b_a_s_h___p_r_o_f_i_l_e, _~_/_._b_a_s_h___l_o_g_i_n, and _~_/_._p_r_o_f_i_l_e,
       in  that order, and reads and executes commands from the first one that
       exists and is readable.  The ----nnoopprrooffiillee option may be  used  when  the
       shell is started to inhibit this behavior.

       When  a  login  shell  exits, bbaasshh reads and executes commands from the
       file _~_/_._b_a_s_h___l_o_g_o_u_t, if it exists.

       When an interactive shell that is not a login shell  is  started,  bbaasshh
       reads  and executes commands from _~_/_._b_a_s_h_r_c, if that file exists.  This
       may be inhibited by using the ----nnoorrcc option.  The ----rrccffiillee _f_i_l_e  option
       will  force  bbaasshh  to  read  and  execute commands from _f_i_l_e instead of
       _~_/_._b_a_s_h_r_c.

       When bbaasshh is started non-interactively, to  run  a  shell  script,  for
       example, it looks for the variable BBAASSHH__EENNVV in the environment, expands
       its value if it appears there, and uses the expanded value as the  name
       of  a  file to read and execute.  BBaasshh behaves as if the following com-
       mand were executed:
              if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
       but the value of the PPAATTHH variable is not used to search for the  file-
       name.

       If  bbaasshh  is  invoked  with  the name sshh, it tries to mimic the startup
       behavior of historical versions of sshh as  closely  as  possible,  while
       conforming  to the POSIX standard as well.  When invoked as an interac-
       tive login shell, or a non-interactive shell with the  ----llooggiinn  option,
       it  first  attempts  to read and execute commands from _/_e_t_c_/_p_r_o_f_i_l_e and
       _~_/_._p_r_o_f_i_l_e, in that order.  The  ----nnoopprrooffiillee  option  may  be  used  to
       inhibit  this  behavior.  When invoked as an interactive shell with the
       name sshh, bbaasshh looks for the variable EENNVV, expands its value  if  it  is
       defined,  and uses the expanded value as the name of a file to read and
       execute.  Since a shell invoked as sshh does not attempt to read and exe-
       cute  commands from any other startup files, the ----rrccffiillee option has no
       effect.  A non-interactive shell invoked with  the  name  sshh  does  not
       attempt  to  read  any  other  startup files.  When invoked as sshh, bbaasshh
       enters _p_o_s_i_x mode after the startup files are read.

       When bbaasshh is started in _p_o_s_i_x mode, as with the  ----ppoossiixx  command  line
       option, it follows the POSIX standard for startup files.  In this mode,
       interactive shells expand the EENNVV variable and commands  are  read  and
       executed  from  the  file  whose  name is the expanded value.  No other
       startup files are read.

       BBaasshh attempts to determine when it is being run with its standard input
       connected to a network connection, as when executed by the remote shell
       daemon, usually _r_s_h_d, or the secure shell daemon _s_s_h_d.  If bbaasshh  deter-
       mines  it  is being run in this fashion, it reads and executes commands
       from _~_/_._b_a_s_h_r_c, if that file exists and is readable.  It  will  not  do
       this  if  invoked as sshh.  The ----nnoorrcc option may be used to inhibit this
       behavior, and the ----rrccffiillee option may be used to force another file  to
       be  read,  but  neither  _r_s_h_d  nor _s_s_h_d generally invoke the shell with
       those options or allow them to be specified.

       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 supplied, no startup
       files are read, shell functions are not inherited from the environment,
       the  SSHHEELLLLOOPPTTSS,  BBAASSHHOOPPTTSS,  CCDDPPAATTHH,  and  GGLLOOBBIIGGNNOORREE variables, if they
       appear in the environment, are ignored, and the effective  user  id  is
       set  to  the real user id.  If the --pp option is supplied at invocation,
       the startup behavior is the same, but the  effective  user  id  is  not
       reset.

DDEEFFIINNIITTIIOONNSS
       The  following  definitions  are used throughout the rest of this docu-
       ment.
       bbllaannkk  A space or tab.
       wwoorrdd   A sequence of characters considered as  a  single  unit  by  the
              shell.  Also known as a ttookkeenn.
       nnaammee   A  _w_o_r_d  consisting  only  of alphanumeric characters and under-
              scores, and beginning with an alphabetic character or an  under-
              score.  Also referred to as an iiddeennttiiffiieerr.
       mmeettaacchhaarraacctteerr
              A  character  that,  when unquoted, separates words.  One of the
              following:
              ||  && ;; (( )) << >> ssppaaccee ttaabb
       ccoonnttrrooll ooppeerraattoorr
              A _t_o_k_e_n that performs a control function.  It is one of the fol-
              lowing symbols:
              |||| && &&&& ;; ;;;; (( )) || ||&& <<nneewwlliinnee>>

RREESSEERRVVEEDD WWOORRDDSS
       _R_e_s_e_r_v_e_d _w_o_r_d_s are words that have a special meaning to the shell.  The
       following words are recognized as reserved when unquoted and either the
       first  word  of a simple command (see SSHHEELLLL GGRRAAMMMMAARR below) or the third
       word of a ccaassee or ffoorr command:

       !! ccaassee  ccoopprroocc  ddoo ddoonnee eelliiff eellssee eessaacc ffii ffoorr  ffuunnccttiioonn  iiff  iinn  sseelleecctt
       tthheenn uunnttiill wwhhiillee {{ }} ttiimmee [[[[ ]]]]

SSHHEELLLL GGRRAAMMMMAARR
   SSiimmppllee CCoommmmaannddss
       A  _s_i_m_p_l_e  _c_o_m_m_a_n_d  is a sequence of optional variable assignments fol-
       lowed by bbllaannkk-separated words and redirections, and  terminated  by  a
       _c_o_n_t_r_o_l _o_p_e_r_a_t_o_r.  The first word specifies the command to be executed,
       and is passed as argument zero.  The  remaining  words  are  passed  as
       arguments to the invoked command.

       The  return  value  of a _s_i_m_p_l_e _c_o_m_m_a_n_d is its exit status, or 128+_n if
       the command is terminated by signal _n.

   PPiippeelliinneess
       A _p_i_p_e_l_i_n_e is a sequence of one or more commands separated  by  one  of
       the control operators || or ||&&.  The format for a pipeline is:

              [ttiimmee [--pp]] [ ! ] _c_o_m_m_a_n_d [ [|||||&&] _c_o_m_m_a_n_d_2 ... ]

       The  standard output of _c_o_m_m_a_n_d is connected via a pipe to the standard
       input of _c_o_m_m_a_n_d_2.  This connection is performed  before  any  redirec-
       tions specified by the command (see RREEDDIIRREECCTTIIOONN below).  If ||&& is used,
       _c_o_m_m_a_n_d's standard error, in addition to its standard output,  is  con-
       nected  to  _c_o_m_m_a_n_d_2's standard input through the pipe; it is shorthand
       for 22>>&&11 ||.  This implicit redirection of the  standard  error  to  the
       standard  output  is  performed after any redirections specified by the
       command.

       The return status of a pipeline is the exit status of the last command,
       unless  the  ppiippeeffaaiill  option  is enabled.  If ppiippeeffaaiill is enabled, the
       pipeline's return status is the value of the last  (rightmost)  command
       to  exit  with a non-zero status, or zero if all commands exit success-
       fully.  If the reserved word !!  precedes a pipeline, the exit status of
       that  pipeline  is the logical negation of the exit status as described
       above.  The shell waits for all commands in the pipeline  to  terminate
       before returning a value.

       If  the  ttiimmee reserved word precedes a pipeline, the elapsed as well as
       user and system time consumed by its execution are  reported  when  the
       pipeline  terminates.   The --pp option changes the output format to that
       specified by POSIX.  When the shell is in _p_o_s_i_x _m_o_d_e, it does not  rec-
       ognize  ttiimmee  as  a  reserved word if the next token begins with a `-'.
       The TTIIMMEEFFOORRMMAATT variable may be set to a format  string  that  specifies
       how  the timing information should be displayed; see the description of
       TTIIMMEEFFOORRMMAATT under SShheellll VVaarriiaabblleess below.

       When the shell is in _p_o_s_i_x _m_o_d_e, ttiimmee may be followed by a newline.  In
       this  case,  the shell displays the total user and system time consumed
       by the shell and its children.  The TTIIMMEEFFOORRMMAATT variable may be used  to
       specify the format of the time information.

       Each  command in a pipeline is executed as a separate process (i.e., in
       a subshell).

   LLiissttss
       A _l_i_s_t is a sequence of one or more pipelines separated by one  of  the
       operators ;;, &&, &&&&, or ||||, and optionally terminated by one of ;;, &&, or
       <<nneewwlliinnee>>.

       Of these list operators, &&&& and |||| have equal precedence, followed by ;;
       and &&, which have equal precedence.

       A  sequence  of  one or more newlines may appear in a _l_i_s_t instead of a
       semicolon to delimit commands.

       If a command is terminated by the control operator &&,  the  shell  exe-
       cutes  the command in the _b_a_c_k_g_r_o_u_n_d in a subshell.  The shell does not
       wait for the command to finish, and the return status is  0.   Commands
       separated  by  a  ;; are executed sequentially; the shell waits for each
       command to terminate in turn.  The return status is the exit status  of
       the last command executed.

       AND  and  OR  lists are sequences of one of more pipelines separated by
       the &&&& and |||| control operators, respectively.  AND and  OR  lists  are
       executed with left associativity.  An AND list has the form

              _c_o_m_m_a_n_d_1 &&&& _c_o_m_m_a_n_d_2

       _c_o_m_m_a_n_d_2  is  executed if, and only if, _c_o_m_m_a_n_d_1 returns an exit status
       of zero.

       An OR list has the form

              _c_o_m_m_a_n_d_1 |||| _c_o_m_m_a_n_d_2


       _c_o_m_m_a_n_d_2 is executed if and only if _c_o_m_m_a_n_d_1 returns  a  non-zero  exit
       status.   The  return  status of AND and OR lists is the exit status of
       the last command executed in the list.

   CCoommppoouunndd CCoommmmaannddss
       A _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d is one of the following.  In most cases a _l_i_s_t in  a
       command's  description may be separated from the rest of the command by
       one or more newlines, and may be followed by a newline in  place  of  a
       semicolon.

       (_l_i_s_t) _l_i_s_t  is  executed in a subshell environment (see CCOOMMMMAANNDD EEXXEECCUU--
              TTIIOONN EENNVVIIRROONNMMEENNTT below).  Variable assignments and builtin  com-
              mands  that  affect  the  shell's  environment  do not remain in
              effect after the command completes.  The return  status  is  the
              exit status of _l_i_s_t.

       { _l_i_s_t; }
              _l_i_s_t  is simply executed in the current shell environment.  _l_i_s_t
              must be terminated with a newline or semicolon.  This  is  known
              as  a  _g_r_o_u_p  _c_o_m_m_a_n_d.   The return status is the exit status of
              _l_i_s_t.  Note that unlike the metacharacters (( and )), {{ and }}  are
              _r_e_s_e_r_v_e_d _w_o_r_d_s and must occur where a reserved word is permitted
              to be recognized.  Since they do not cause a  word  break,  they
              must  be  separated  from  _l_i_s_t  by  whitespace or another shell
              metacharacter.

       ((_e_x_p_r_e_s_s_i_o_n))
              The _e_x_p_r_e_s_s_i_o_n is evaluated according  to  the  rules  described
              below  under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN.  If the value of the expres-
              sion is non-zero, the return status is 0; otherwise  the  return
              status is 1.  This is exactly equivalent to lleett ""_e_x_p_r_e_s_s_i_o_n"".

       [[[[ _e_x_p_r_e_s_s_i_o_n ]]]]
              Return  a  status  of  0 or 1 depending on the evaluation of the
              conditional expression _e_x_p_r_e_s_s_i_o_n.  Expressions are composed  of
              the  primaries  described  below  under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS.
              Word splitting and pathname expansion are not performed  on  the
              words  between  the  [[[[  and  ]]]]; tilde expansion, parameter and
              variable expansion, arithmetic expansion, command  substitution,
              process  substitution,  and quote removal are performed.  Condi-
              tional operators such as --ff must be unquoted to be recognized as
              primaries.

              When  used with [[[[, the << and >> operators sort lexicographically
              using the current locale.

              When the ==== and !!== operators are used, the string to  the  right
              of the operator is considered a pattern and matched according to
              the rules described below under PPaatttteerrnn MMaattcchhiinngg, as if the eexxtt--
              gglloobb shell option were enabled.  The == operator is equivalent to
              ====.  If the shell option nnooccaasseemmaattcchh is enabled,  the  match  is
              performed  without  regard to the case of alphabetic characters.
              The return value is 0 if the string matches  (====)  or  does  not
              match  (!!==)  the pattern, and 1 otherwise.  Any part of the pat-
              tern may be quoted to force the quoted portion to be matched  as
              a string.

              An  additional  binary operator, ==~~, is available, with the same
              precedence as ==== and !!==.  When it is used,  the  string  to  the
              right  of the operator is considered an extended regular expres-
              sion and matched accordingly (as in _r_e_g_e_x(3)).  The return value
              is 0 if the string matches the pattern, and 1 otherwise.  If the
              regular expression is syntactically incorrect,  the  conditional
              expression's return value is 2.  If the shell option nnooccaasseemmaattcchh
              is enabled, the match is performed without regard to the case of
              alphabetic characters.  Any part of the pattern may be quoted to
              force the quoted portion to be matched  as  a  string.   Bracket
              expressions  in  regular  expressions must be treated carefully,
              since normal quoting  characters  lose  their  meanings  between
              brackets.  If the pattern is stored in a shell variable, quoting
              the variable expansion forces the entire pattern to  be  matched
              as a string.  Substrings matched by parenthesized subexpressions
              within the regular expression are saved in  the  array  variable
              BBAASSHH__RREEMMAATTCCHH.   The  element of BBAASSHH__RREEMMAATTCCHH with index 0 is the
              portion of the string matching the  entire  regular  expression.
              The  element  of BBAASSHH__RREEMMAATTCCHH with index _n is the portion of the
              string matching the _nth parenthesized subexpression.

              Expressions may  be  combined  using  the  following  operators,
              listed in decreasing order of precedence:

              (( _e_x_p_r_e_s_s_i_o_n ))
                     Returns  the  value  of  _e_x_p_r_e_s_s_i_o_n.  This may be used to
                     override the normal precedence of operators.
              !! _e_x_p_r_e_s_s_i_o_n
                     True if _e_x_p_r_e_s_s_i_o_n is false.
              _e_x_p_r_e_s_s_i_o_n_1 &&&& _e_x_p_r_e_s_s_i_o_n_2
                     True if both _e_x_p_r_e_s_s_i_o_n_1 and _e_x_p_r_e_s_s_i_o_n_2 are true.
              _e_x_p_r_e_s_s_i_o_n_1 |||| _e_x_p_r_e_s_s_i_o_n_2
                     True if either _e_x_p_r_e_s_s_i_o_n_1 or _e_x_p_r_e_s_s_i_o_n_2 is true.

              The &&&& and |||| operators do not evaluate _e_x_p_r_e_s_s_i_o_n_2 if the value
              of  _e_x_p_r_e_s_s_i_o_n_1  is  sufficient to determine the return value of
              the entire conditional expression.

       ffoorr _n_a_m_e [ [ iinn [ _w_o_r_d _._._. ] ] ; ] ddoo _l_i_s_t ; ddoonnee
              The list of words following iinn is expanded, generating a list of
              items.  The variable _n_a_m_e is set to each element of this list in
              turn, and _l_i_s_t is executed each time.  If the iinn _w_o_r_d  is  omit-
              ted,  the  ffoorr  command  executes  _l_i_s_t once for each positional
              parameter that is set (see PPAARRAAMMEETTEERRSS below).  The return status
              is  the  exit  status of the last command that executes.  If the
              expansion of the items following iinn results in an empty list, no
              commands are executed, and the return status is 0.

       ffoorr (( _e_x_p_r_1 ; _e_x_p_r_2 ; _e_x_p_r_3 )) ; ddoo _l_i_s_t ; ddoonnee
              First, the arithmetic expression _e_x_p_r_1 is evaluated according to
              the rules described  below  under  AARRIITTHHMMEETTIICC  EEVVAALLUUAATTIIOONN.   The
              arithmetic  expression  _e_x_p_r_2 is then evaluated repeatedly until
              it evaluates to zero.  Each time _e_x_p_r_2 evaluates to  a  non-zero
              value,  _l_i_s_t  is executed and the arithmetic expression _e_x_p_r_3 is
              evaluated.  If any expression is omitted, it behaves  as  if  it
              evaluates to 1.  The return value is the exit status of the last
              command in _l_i_s_t that is executed, or false if any of the expres-
              sions is invalid.

       sseelleecctt _n_a_m_e [ iinn _w_o_r_d ] ; ddoo _l_i_s_t ; ddoonnee
              The list of words following iinn is expanded, generating a list of
              items.  The set of expanded words is  printed  on  the  standard
              error,  each  preceded  by a number.  If the iinn _w_o_r_d is omitted,
              the positional parameters are printed  (see  PPAARRAAMMEETTEERRSS  below).
              The  PPSS33 prompt is then displayed and a line read from the stan-
              dard input.  If the line consists of a number  corresponding  to
              one  of  the  displayed  words, then the value of _n_a_m_e is set to
              that word.  If the line is empty, the words and prompt are  dis-
              played again.  If EOF is read, the command completes.  Any other
              value read causes _n_a_m_e to be set to  null.   The  line  read  is
              saved  in  the  variable RREEPPLLYY.  The _l_i_s_t is executed after each
              selection until a bbrreeaakk command is executed.  The exit status of
              sseelleecctt  is the exit status of the last command executed in _l_i_s_t,
              or zero if no commands were executed.

       ccaassee _w_o_r_d iinn [ [(] _p_a_t_t_e_r_n [ || _p_a_t_t_e_r_n ] ... ) _l_i_s_t ;; ] ... eessaacc
              A ccaassee command first expands _w_o_r_d, and tries to match it against
              each _p_a_t_t_e_r_n in turn, using the same matching rules as for path-
              name expansion (see PPaatthhnnaammee  EExxppaannssiioonn  below).   The  _w_o_r_d  is
              expanded  using  tilde  expansion, parameter and variable expan-
              sion, arithmetic  substitution,  command  substitution,  process
              substitution  and  quote  removal.   Each  _p_a_t_t_e_r_n  examined  is
              expanded using tilde expansion, parameter  and  variable  expan-
              sion, arithmetic substitution, command substitution, and process
              substitution.  If the shell option nnooccaasseemmaattcchh is  enabled,  the
              match  is  performed  without  regard  to the case of alphabetic
              characters.  When a match is found, the  corresponding  _l_i_s_t  is
              executed.  If the ;;;; operator is used, no subsequent matches are
              attempted after the first pattern match.  Using ;;&& in  place  of
              ;;;;  causes  execution  to continue with the _l_i_s_t associated with
              the next set of patterns.  Using ;;;;&& in place of ;;;;  causes  the
              shell  to  test  the next pattern list in the statement, if any,
              and execute any associated _l_i_s_t on a successful match.  The exit
              status is zero if no pattern matches.  Otherwise, it is the exit
              status of the last command executed in _l_i_s_t.

       iiff _l_i_s_t; tthheenn _l_i_s_t; [ eelliiff _l_i_s_t; tthheenn _l_i_s_t; ] ... [ eellssee _l_i_s_t; ] ffii
              The iiff _l_i_s_t is executed.  If its exit status is zero,  the  tthheenn
              _l_i_s_t  is  executed.   Otherwise,  each  eelliiff _l_i_s_t is executed in
              turn, and if its exit status is  zero,  the  corresponding  tthheenn
              _l_i_s_t is executed and the command completes.  Otherwise, the eellssee
              _l_i_s_t is executed, if present.  The exit status is the exit  sta-
              tus of the last command executed, or zero if no condition tested
              true.

       wwhhiillee _l_i_s_t_-_1; ddoo _l_i_s_t_-_2; ddoonnee
       uunnttiill _l_i_s_t_-_1; ddoo _l_i_s_t_-_2; ddoonnee
              The wwhhiillee command continuously executes the list _l_i_s_t_-_2 as  long
              as the last command in the list _l_i_s_t_-_1 returns an exit status of
              zero.  The uunnttiill command is  identical  to  the  wwhhiillee  command,
              except  that  the test is negated; _l_i_s_t_-_2 is executed as long as
              the last command in _l_i_s_t_-_1 returns a non-zero exit status.   The
              exit  status  of the wwhhiillee and uunnttiill commands is the exit status
              of the last command executed in _l_i_s_t_-_2, or zero if none was exe-
              cuted.

   CCoopprroocceesssseess
       A _c_o_p_r_o_c_e_s_s is a shell command preceded by the ccoopprroocc reserved word.  A
       coprocess is executed asynchronously in a subshell, as if  the  command
       had  been  terminated  with the && control operator, with a two-way pipe
       established between the executing shell and the coprocess.

       The format for a coprocess is:

              ccoopprroocc [_N_A_M_E] _c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n_s]

       This creates a coprocess named _N_A_M_E.  If  _N_A_M_E  is  not  supplied,  the
       default name is CCOOPPRROOCC.  _N_A_M_E must not be supplied if _c_o_m_m_a_n_d is a _s_i_m_-
       _p_l_e _c_o_m_m_a_n_d (see above); otherwise, it is interpreted as the first word
       of  the simple command.  When the coprocess is executed, the shell cre-
       ates an array variable (see AArrrraayyss below) named _N_A_M_E in the context  of
       the executing shell.  The standard output of _c_o_m_m_a_n_d is connected via a
       pipe to a file  descriptor  in  the  executing  shell,  and  that  file
       descriptor  is  assigned  to _N_A_M_E[0].  The standard input of _c_o_m_m_a_n_d is
       connected via a pipe to a file descriptor in the executing  shell,  and
       that  file descriptor is assigned to _N_A_M_E[1].  This pipe is established
       before any redirections  specified  by  the  command  (see  RREEDDIIRREECCTTIIOONN
       below).   The  file  descriptors  can be utilized as arguments to shell
       commands and redirections using standard  word  expansions.   The  file
       descriptors  are  not  available  in  subshells.  The process ID of the
       shell spawned to execute the coprocess is available as the value of the
       variable  _N_A_M_E_PID.   The  wwaaiitt builtin command may be used to wait for
       the coprocess to terminate.

       Since the coprocess is created as an asynchronous command,  the  ccoopprroocc
       command  always  returns  success.  The return status of a coprocess is
       the exit status of _c_o_m_m_a_n_d.

   SShheellll FFuunnccttiioonn DDeeffiinniittiioonnss
       A shell function is an object that is called like a simple command  and
       executes  a  compound  command with a new set of positional parameters.
       Shell functions are declared as follows:

       _n_a_m_e () _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n]
       ffuunnccttiioonn _n_a_m_e [()] _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n]
              This defines a function named _n_a_m_e.  The reserved word  ffuunnccttiioonn
              is  optional.   If  the  ffuunnccttiioonn reserved word is supplied, the
              parentheses are optional.  The _b_o_d_y of the function is the  com-
              pound  command  _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d  (see CCoommppoouunndd CCoommmmaannddss above).
              That command is usually a _l_i_s_t of commands between { and },  but
              may  be  any command listed under CCoommppoouunndd CCoommmmaannddss above.  _c_o_m_-
              _p_o_u_n_d_-_c_o_m_m_a_n_d is executed whenever _n_a_m_e is specified as the name
              of  a  simple  command.  When in _p_o_s_i_x _m_o_d_e, _n_a_m_e may not be the
              name of one of the POSIX  _s_p_e_c_i_a_l  _b_u_i_l_t_i_n_s.   Any  redirections
              (see RREEDDIIRREECCTTIIOONN below) specified when a function is defined are
              performed when the function is executed.  The exit status  of  a
              function  definition  is  zero unless a syntax error occurs or a
              readonly function with the same name already exists.  When  exe-
              cuted,  the  exit status of a function is the exit status of the
              last command executed in the body.  (See FFUUNNCCTTIIOONNSS below.)

CCOOMMMMEENNTTSS
       In a non-interactive shell, or an interactive shell in which the iinntteerr--
       aaccttiivvee__ccoommmmeennttss  option  to  the  sshhoopptt  builtin  is enabled (see SSHHEELLLL
       BBUUIILLTTIINN CCOOMMMMAANNDDSS below), a word beginning with ## causes that  word  and
       all  remaining  characters  on that line to be ignored.  An interactive
       shell without the iinntteerraaccttiivvee__ccoommmmeennttss option enabled  does  not  allow
       comments.  The iinntteerraaccttiivvee__ccoommmmeennttss option is on by default in interac-
       tive shells.

QQUUOOTTIINNGG
       _Q_u_o_t_i_n_g is used to remove the special meaning of certain characters  or
       words  to  the shell.  Quoting can be used to disable special treatment
       for special characters, to prevent reserved words from being recognized
       as such, and to prevent parameter expansion.

       Each  of  the _m_e_t_a_c_h_a_r_a_c_t_e_r_s listed above under DDEEFFIINNIITTIIOONNSS has special
       meaning to the shell and must be quoted if it is to represent itself.

       When the command history expansion facilities are being used (see  HHIISS--
       TTOORRYY EEXXPPAANNSSIIOONN below), the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, usually !!, must
       be quoted to prevent history expansion.

       There are  three  quoting  mechanisms:  the  _e_s_c_a_p_e  _c_h_a_r_a_c_t_e_r,  single
       quotes, and double quotes.

       A  non-quoted  backslash (\\) is the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r.  It preserves the
       literal value of the next character that follows, with the exception of
       <newline>.   If  a  \\<newline>  pair  appears, and the backslash is not
       itself quoted, the \\<newline> is treated as a line  continuation  (that
       is, it is removed from the input stream and effectively ignored).

       Enclosing  characters  in  single quotes preserves the literal value of
       each character within the quotes.  A single quote may not occur between
       single quotes, even when preceded by a backslash.

       Enclosing  characters  in  double quotes preserves the literal value of
       all characters within the quotes, with the exception of $$, ``,  \\,  and,
       when  history  expansion  is enabled, !!.  The characters $$ and `` retain
       their special meaning within double quotes.  The backslash retains  its
       special  meaning only when followed by one of the following characters:
       $$, ``, "", \\, or <<nneewwlliinnee>>.  A double quote may be quoted  within  double
       quotes by preceding it with a backslash.  If enabled, history expansion
       will be performed unless an !!  appearing in double  quotes  is  escaped
       using a backslash.  The backslash preceding the !!  is not removed.

       The  special  parameters  **  and  @@ have special meaning when in double
       quotes (see PPAARRAAMMEETTEERRSS below).

       Words of the form $$'_s_t_r_i_n_g' are treated specially.  The word expands to
       _s_t_r_i_n_g,  with backslash-escaped characters replaced as specified by the
       ANSI C standard.  Backslash escape sequences, if present,  are  decoded
       as follows:
              \\aa     alert (bell)
              \\bb     backspace
              \\ee
              \\EE     an escape character
              \\ff     form feed
              \\nn     new line
              \\rr     carriage return
              \\tt     horizontal tab
              \\vv     vertical tab
              \\\\     backslash
              \\''     single quote
              \\""     double quote
              \\_n_n_n   the  eight-bit  character  whose value is the octal value
                     _n_n_n (one to three digits)
              \\xx_H_H   the eight-bit character whose value  is  the  hexadecimal
                     value _H_H (one or two hex digits)
              \\uu_H_H_H_H the  Unicode (ISO/IEC 10646) character whose value is the
                     hexadecimal value _H_H_H_H (one to four hex digits)
              \\UU_H_H_H_H_H_H_H_H
                     the Unicode (ISO/IEC 10646) character whose value is  the
                     hexadecimal value _H_H_H_H_H_H_H_H (one to eight hex digits)
              \\cc_x    a control-_x character

       The  expanded  result  is  single-quoted, as if the dollar sign had not
       been present.

       A double-quoted string preceded by a dollar sign ($$"_s_t_r_i_n_g") will cause
       the  string  to  be translated according to the current locale.  If the
       current locale is CC or PPOOSSIIXX, the  dollar  sign  is  ignored.   If  the
       string is translated and replaced, the replacement is double-quoted.

PPAARRAAMMEETTEERRSS
       A  _p_a_r_a_m_e_t_e_r is an entity that stores values.  It can be a _n_a_m_e, a num-
       ber, or one of the special characters listed below under SSppeecciiaall PPaarraamm--
       eetteerrss.   A _v_a_r_i_a_b_l_e is a parameter denoted by a _n_a_m_e.  A variable has a
       _v_a_l_u_e and zero or more _a_t_t_r_i_b_u_t_e_s.  Attributes are assigned  using  the
       ddeeccllaarree  builtin command (see ddeeccllaarree below in SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS).

       A parameter is set if it has been assigned a value.  The null string is
       a  valid  value.  Once a variable is set, it may be unset only by using
       the uunnsseett builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).

       A _v_a_r_i_a_b_l_e may be assigned to by a statement of the form

              _n_a_m_e=[_v_a_l_u_e]

       If _v_a_l_u_e is not given, the variable is assigned the null  string.   All
       _v_a_l_u_e_s  undergo tilde expansion, parameter and variable expansion, com-
       mand substitution, arithmetic expansion, and quote removal (see  EEXXPPAANN--
       SSIIOONN below).  If the variable has its iinntteeggeerr attribute set, then _v_a_l_u_e
       is evaluated as an arithmetic expression even if the $((...)) expansion
       is  not  used  (see AArriitthhmmeettiicc EExxppaannssiioonn below).  Word splitting is not
       performed, with the exception of ""$$@@"" as explained below under  SSppeecciiaall
       PPaarraammeetteerrss.   Pathname  expansion  is not performed.  Assignment state-
       ments may also appear as arguments  to  the  aalliiaass,  ddeeccllaarree,  ttyyppeesseett,
       eexxppoorrtt,  rreeaaddoonnllyy,  and  llooccaall  builtin  commands.  When in _p_o_s_i_x _m_o_d_e,
       these builtins may appear in a command after one or more  instances  of
       the ccoommmmaanndd builtin and retain these assignment statement properties.

       In  the context where an assignment statement is assigning a value to a
       shell variable or array index, the += operator can be used to append to
       or add to the variable's previous value.  When += is applied to a vari-
       able for which the _i_n_t_e_g_e_r attribute has been set, _v_a_l_u_e  is  evaluated
       as  an arithmetic expression and added to the variable's current value,
       which is also evaluated.  When += is applied to an array variable using
       compound  assignment  (see  AArrrraayyss  below), the variable's value is not
       unset (as it is when using =), and new values are appended to the array
       beginning  at  one  greater than the array's maximum index (for indexed
       arrays) or added as additional key-value pairs in an associative array.
       When  applied  to  a  string-valued  variable,  _v_a_l_u_e  is  expanded and
       appended to the variable's value.

       A variable can be assigned the _n_a_m_e_r_e_f attribute using the --nn option to
       the  ddeeccllaarree or llooccaall builtin commands (see the descriptions of ddeeccllaarree
       and llooccaall below) to create a _n_a_m_e_r_e_f, or a reference to  another  vari-
       able.   This  allows  variables to be manipulated indirectly.  Whenever
       the nameref variable is referenced or assigned  to,  the  operation  is
       actually  performed on the variable specified by the nameref variable's
       value.  A nameref is commonly used within shell functions to refer to a
       variable  whose  name  is  passed  as an argument to the function.  For
       instance, if a variable name is passed to a shell function as its first
       argument, running
              declare -n ref=$1
       inside  the  function creates a nameref variable rreeff whose value is the
       variable name passed as the first argument.  References and assignments
       to  rreeff are treated as references and assignments to the variable whose
       name was passed as $$11.  If the control variable in a ffoorr loop  has  the
       nameref  attribute, the list of words can be a list of shell variables,
       and a name reference will be established for each word in the list,  in
       turn,  when  the loop is executed.  Array variables cannot be given the
       --nn attribute.  However, nameref variables can reference array variables
       and  subscripted  array  variables.  Namerefs can be unset using the --nn
       option to the uunnsseett builtin.  Otherwise, if uunnsseett is executed with  the
       name  of  a nameref variable as an argument, the variable referenced by
       the nameref variable will be unset.

   PPoossiittiioonnaall PPaarraammeetteerrss
       A _p_o_s_i_t_i_o_n_a_l _p_a_r_a_m_e_t_e_r is a parameter denoted by one  or  more  digits,
       other than the single digit 0.  Positional parameters are assigned from
       the shell's arguments when it is invoked, and may be  reassigned  using
       the  sseett builtin command.  Positional parameters may not be assigned to
       with assignment statements.  The positional parameters are  temporarily
       replaced when a shell function is executed (see FFUUNNCCTTIIOONNSS below).

       When  a  positional parameter consisting of more than a single digit is
       expanded, it must be enclosed in braces (see EEXXPPAANNSSIIOONN below).

   SSppeecciiaall PPaarraammeetteerrss
       The shell treats several parameters specially.   These  parameters  may
       only be referenced; assignment to them is not allowed.
       **      Expands  to  the positional parameters, starting from one.  When
              the expansion is  not  within  double  quotes,  each  positional
              parameter  expands  to a separate word.  In contexts where it is
              performed, those words are subject to further word splitting and
              pathname  expansion.   When  the  expansion occurs within double
              quotes, it expands to a single  word  with  the  value  of  each
              parameter  separated  by  the first character of the IIFFSS special
              variable.  That is, "$$**" is equivalent to "$$11_c$$22_c......",  where  _c
              is the first character of the value of the IIFFSS variable.  If IIFFSS
              is unset, the parameters are separated by  spaces.   If  IIFFSS  is
              null,  the parameters are joined without intervening separators.
       @@      Expands to the positional parameters, starting from  one.   When
              the  expansion  occurs  within  double  quotes,  each  parameter
              expands to a separate word.  That is, "$$@@" is equivalent to "$$11"
              "$$22"  ...   If the double-quoted expansion occurs within a word,
              the expansion of the first parameter is joined with  the  begin-
              ning  part  of  the original word, and the expansion of the last
              parameter is joined with the last part  of  the  original  word.
              When  there  are no positional parameters, "$$@@" and $$@@ expand to
              nothing (i.e., they are removed).
       ##      Expands to the number of positional parameters in decimal.
       ??      Expands to the exit status of the most recently  executed  fore-
              ground pipeline.
       --      Expands  to  the  current option flags as specified upon invoca-
              tion, by the sseett builtin command, or  those  set  by  the  shell
              itself (such as the --ii option).
       $$      Expands  to  the  process ID of the shell.  In a () subshell, it
              expands to the process ID of the current  shell,  not  the  sub-
              shell.
       !!      Expands  to  the process ID of the job most recently placed into
              the background, whether executed as an asynchronous  command  or
              using the bbgg builtin (see JJOOBB CCOONNTTRROOLL below).
       00      Expands  to  the name of the shell or shell script.  This is set
              at shell initialization.  If bbaasshh is invoked with a file of com-
              mands,  $$00  is set to the name of that file.  If bbaasshh is started
              with the --cc option, then $$00 is set to the first  argument  after
              the  string to be executed, if one is present.  Otherwise, it is
              set to the filename used to invoke bbaasshh, as  given  by  argument
              zero.
       __      At  shell  startup,  set to the absolute pathname used to invoke
              the shell or shell script being executed as passed in the  envi-
              ronment  or  argument  list.   Subsequently, expands to the last
              argument to the previous command, after expansion.  Also set  to
              the  full  pathname  used  to  invoke  each command executed and
              placed in the environment exported to that command.  When check-
              ing  mail,  this  parameter holds the name of the mail file cur-
              rently being checked.

   SShheellll VVaarriiaabblleess
       The following variables are set by the shell:

       BBAASSHH   Expands to the full filename used to  invoke  this  instance  of
              bbaasshh.
       BBAASSHHOOPPTTSS
              A  colon-separated  list of enabled shell options.  Each word in
              the list is a valid argument for the  --ss  option  to  the  sshhoopptt
              builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  The options
              appearing in BBAASSHHOOPPTTSS are those reported as  _o_n  by  sshhoopptt.   If
              this  variable  is  in the environment when bbaasshh starts up, each
              shell option in the list will  be  enabled  before  reading  any
              startup files.  This variable is read-only.
       BBAASSHHPPIIDD
              Expands  to  the  process  ID of the current bbaasshh process.  This
              differs from $$$$ under certain circumstances, such  as  subshells
              that do not require bbaasshh to be re-initialized.
       BBAASSHH__AALLIIAASSEESS
              An  associative  array  variable whose members correspond to the
              internal list of aliases as maintained  by  the  aalliiaass  builtin.
              Elements added to this array appear in the alias list; unsetting
              array elements cause aliases to be removed from the alias  list.
       BBAASSHH__AARRGGCC
              An  array  variable whose values are the number of parameters in
              each frame of the current bbaasshh execution call stack.  The number
              of  parameters  to  the  current  subroutine  (shell function or
              script executed with .. or ssoouurrccee) is at the top  of  the  stack.
              When  a  subroutine is executed, the number of parameters passed
              is pushed onto BBAASSHH__AARRGGCC.  The shell sets BBAASSHH__AARRGGCC only when in
              extended  debugging  mode  (see  the description of the eexxttddeebbuugg
              option to the sshhoopptt builtin below)
       BBAASSHH__AARRGGVV
              An array variable containing all of the parameters in  the  cur-
              rent bbaasshh execution call stack.  The final parameter of the last
              subroutine call is at the top of the stack; the first  parameter
              of the initial call is at the bottom.  When a subroutine is exe-
              cuted, the parameters supplied are pushed onto  BBAASSHH__AARRGGVV.   The
              shell  sets  BBAASSHH__AARRGGVV only when in extended debugging mode (see
              the description of the eexxttddeebbuugg  option  to  the  sshhoopptt  builtin
              below)
       BBAASSHH__CCMMDDSS
              An  associative  array  variable whose members correspond to the
              internal hash table  of  commands  as  maintained  by  the  hhaasshh
              builtin.  Elements added to this array appear in the hash table;
              unsetting array elements cause commands to be removed  from  the
              hash table.
       BBAASSHH__CCOOMMMMAANNDD
              The  command  currently  being executed or about to be executed,
              unless the shell is executing a command as the result of a trap,
              in  which  case  it  is the command executing at the time of the
              trap.
       BBAASSHH__EEXXEECCUUTTIIOONN__SSTTRRIINNGG
              The command argument to the --cc invocation option.
       BBAASSHH__LLIINNEENNOO
              An array variable whose members are the line numbers  in  source
              files  where  each corresponding member of FFUUNNCCNNAAMMEE was invoked.
              $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}}  is  the  line  number  in  the  source  file
              ($${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}})  where  $${{FFUUNNCCNNAAMMEE[[_$_i]]}}  was  called  (or
              $${{BBAASSHH__LLIINNEENNOO[[_$_i_-_1]]}} if referenced within  another  shell  func-
              tion).  Use LLIINNEENNOO to obtain the current line number.
       BBAASSHH__RREEMMAATTCCHH
              An  array  variable  whose members are assigned by the ==~~ binary
              operator to the [[[[ conditional command.  The element with  index
              0  is  the  portion  of  the  string matching the entire regular
              expression.  The element with index _n  is  the  portion  of  the
              string matching the _nth parenthesized subexpression.  This vari-
              able is read-only.
       BBAASSHH__SSOOUURRCCEE
              An array variable whose members are the source  filenames  where
              the  corresponding  shell  function  names in the FFUUNNCCNNAAMMEE array
              variable are defined.  The  shell  function  $${{FFUUNNCCNNAAMMEE[[_$_i]]}}  is
              defined   in   the   file  $${{BBAASSHH__SSOOUURRCCEE[[_$_i]]}}  and  called  from
              $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}}.
       BBAASSHH__SSUUBBSSHHEELLLL
              Incremented by one within each subshell or subshell  environment
              when  the  shell begins executing in that environment.  The ini-
              tial value is 0.
       BBAASSHH__VVEERRSSIINNFFOO
              A readonly array variable whose members hold version information
              for  this  instance  of  bbaasshh.  The values assigned to the array
              members are as follows:
              BBAASSHH__VVEERRSSIINNFFOO[[0]]        The major version number (the  _r_e_l_e_a_s_e).
              BBAASSHH__VVEERRSSIINNFFOO[[1]]        The  minor version number (the _v_e_r_s_i_o_n).
              BBAASSHH__VVEERRSSIINNFFOO[[2]]        The patch level.
              BBAASSHH__VVEERRSSIINNFFOO[[3]]        The build version.
              BBAASSHH__VVEERRSSIINNFFOO[[4]]        The release status (e.g., _b_e_t_a_1).
              BBAASSHH__VVEERRSSIINNFFOO[[5]]        The value of MMAACCHHTTYYPPEE.
       BBAASSHH__VVEERRSSIIOONN
              Expands to a string describing the version of this  instance  of
              bbaasshh.
       CCOOMMPP__CCWWOORRDD
              An  index  into $${{CCOOMMPP__WWOORRDDSS}} of the word containing the current
              cursor position.  This variable is available only in shell func-
              tions  invoked  by  the  programmable completion facilities (see
              PPrrooggrraammmmaabbllee CCoommpplleettiioonn below).
       CCOOMMPP__KKEEYY
              The key (or final key of a key sequence) used to invoke the cur-
              rent completion function.
       CCOOMMPP__LLIINNEE
              The  current  command  line.  This variable is available only in
              shell functions  and  external  commands  invoked  by  the  pro-
              grammable  completion  facilities  (see  PPrrooggrraammmmaabbllee CCoommpplleettiioonn
              below).
       CCOOMMPP__PPOOIINNTT
              The index of the current cursor position relative to the  begin-
              ning  of the current command.  If the current cursor position is
              at the end of the current command, the value of this variable is
              equal  to  $${{##CCOOMMPP__LLIINNEE}}.   This  variable  is available only in
              shell functions  and  external  commands  invoked  by  the  pro-
              grammable  completion  facilities  (see  PPrrooggrraammmmaabbllee CCoommpplleettiioonn
              below).
       CCOOMMPP__TTYYPPEE
              Set to an integer value corresponding to the type of  completion
              attempted  that  caused a completion function to be called: _T_A_B,
              for normal completion, _?, for listing completions after  succes-
              sive  tabs,  _!, for listing alternatives on partial word comple-
              tion, _@, to list completions if the word is not  unmodified,  or
              _%,  for  menu  completion.   This  variable is available only in
              shell functions  and  external  commands  invoked  by  the  pro-
              grammable  completion  facilities  (see  PPrrooggrraammmmaabbllee CCoommpplleettiioonn
              below).
       CCOOMMPP__WWOORRDDBBRREEAAKKSS
              The set of characters that the rreeaaddlliinnee library treats  as  word
              separators  when performing word completion.  If CCOOMMPP__WWOORRDDBBRREEAAKKSS
              is unset, it loses its special properties, even if it is  subse-
              quently reset.
       CCOOMMPP__WWOORRDDSS
              An  array variable (see AArrrraayyss below) consisting of the individ-
              ual words in the current command line.  The line is  split  into
              words  as  rreeaaddlliinnee  would  split  it,  using CCOOMMPP__WWOORRDDBBRREEAAKKSS as
              described above.  This variable is available only in shell func-
              tions  invoked  by  the  programmable completion facilities (see
              PPrrooggrraammmmaabbllee CCoommpplleettiioonn below).
       CCOOPPRROOCC An array variable (see AArrrraayyss below) created to  hold  the  file
              descriptors  for  output  from and input to an unnamed coprocess
              (see CCoopprroocceesssseess above).
       DDIIRRSSTTAACCKK
              An array variable (see AArrrraayyss below) containing the current con-
              tents  of  the directory stack.  Directories appear in the stack
              in the order they are displayed by the ddiirrss builtin.   Assigning
              to members of this array variable may be used to modify directo-
              ries already in the stack, but the ppuusshhdd and ppooppdd builtins  must
              be used to add and remove directories.  Assignment to this vari-
              able will not change the  current  directory.   If  DDIIRRSSTTAACCKK  is
              unset,  it  loses  its  special properties, even if it is subse-
              quently reset.
       EEUUIIDD   Expands to the effective user ID of the current  user,  initial-
              ized at shell startup.  This variable is readonly.
       FFUUNNCCNNAAMMEE
              An  array  variable  containing the names of all shell functions
              currently in the execution call stack.  The element with index 0
              is the name of any currently-executing shell function.  The bot-
              tom-most element (the one with the  highest  index)  is  "main".
              This  variable  exists  only when a shell function is executing.
              Assignments to FFUUNNCCNNAAMMEE have no effect and return an error  sta-
              tus.   If  FFUUNNCCNNAAMMEE  is  unset, it loses its special properties,
              even if it is subsequently reset.

              This variable can be  used  with  BBAASSHH__LLIINNEENNOO  and  BBAASSHH__SSOOUURRCCEE.
              Each   element   of   FFUUNNCCNNAAMMEE  has  corresponding  elements  in
              BBAASSHH__LLIINNEENNOO and BBAASSHH__SSOOUURRCCEE to describe  the  call  stack.   For
              instance,    $${{FFUUNNCCNNAAMMEE[[_$_i]]}}    was   called   from   the   file
              $${{BBAASSHH__SSOOUURRCCEE[[_$_i_+_1]]}} at  line  number  $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}}.   The
              ccaalllleerr builtin displays the current call stack using this infor-
              mation.
       GGRROOUUPPSS An array variable containing the list of  groups  of  which  the
              current  user is a member.  Assignments to GGRROOUUPPSS have no effect
              and return an error status.  If GGRROOUUPPSS is unset,  it  loses  its
              special properties, even if it is subsequently reset.
       HHIISSTTCCMMDD
              The history number, or index in the history list, of the current
              command.  If HHIISSTTCCMMDD is unset, it loses its special  properties,
              even if it is subsequently reset.
       HHOOSSTTNNAAMMEE
              Automatically set to the name of the current host.
       HHOOSSTTTTYYPPEE
              Automatically  set  to a string that uniquely describes the type
              of machine on which bbaasshh is executing.  The default  is  system-
              dependent.
       LLIINNEENNOO Each  time this parameter is referenced, the shell substitutes a
              decimal number representing the current sequential  line  number
              (starting  with  1)  within a script or function.  When not in a
              script or function, the value substituted is not  guaranteed  to
              be meaningful.  If LLIINNEENNOO is unset, it loses its special proper-
              ties, even if it is subsequently reset.
       MMAACCHHTTYYPPEE
              Automatically set to a string that fully  describes  the  system
              type  on  which  bbaasshh is executing, in the standard GNU _c_p_u_-_c_o_m_-
              _p_a_n_y_-_s_y_s_t_e_m format.  The default is system-dependent.
       MMAAPPFFIILLEE
              An array variable (see AArrrraayyss below) created to  hold  the  text
              read by the mmaappffiillee builtin when no variable name is supplied.
       OOLLDDPPWWDD The previous working directory as set by the ccdd command.
       OOPPTTAARRGG The  value  of the last option argument processed by the ggeettooppttss
              builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).
       OOPPTTIINNDD The index of the next argument to be processed  by  the  ggeettooppttss
              builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).
       OOSSTTYYPPEE Automatically  set to a string that describes the operating sys-
              tem on which bbaasshh is executing.  The  default  is  system-depen-
              dent.
       PPIIPPEESSTTAATTUUSS
              An  array  variable (see AArrrraayyss below) containing a list of exit
              status values from the processes in  the  most-recently-executed
              foreground pipeline (which may contain only a single command).
       PPPPIIDD   The  process  ID  of the shell's parent.  This variable is read-
              only.
       PPWWDD    The current working directory as set by the ccdd command.
       RRAANNDDOOMM Each time this parameter is referenced, a random integer between
              0 and 32767 is generated.  The sequence of random numbers may be
              initialized by assigning a value to RRAANNDDOOMM.  If RRAANNDDOOMM is unset,
              it  loses  its  special  properties,  even if it is subsequently
              reset.
       RREEAADDLLIINNEE__LLIINNEE
              The contents of the rreeaaddlliinnee line buffer, for use with "bind -x"
              (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).
       RREEAADDLLIINNEE__PPOOIINNTT
              The position of the insertion point in the rreeaaddlliinnee line buffer,
              for use with "bind -x" (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).
       RREEPPLLYY  Set to the line of input read by the rreeaadd builtin  command  when
              no arguments are supplied.
       SSEECCOONNDDSS
              Each  time  this  parameter is referenced, the number of seconds
              since shell invocation is returned.  If a value is  assigned  to
              SSEECCOONNDDSS,  the  value  returned upon subsequent references is the
              number of seconds since the assignment plus the value  assigned.
              If SSEECCOONNDDSS is unset, it loses its special properties, even if it
              is subsequently reset.
       SSHHEELLLLOOPPTTSS
              A colon-separated list of enabled shell options.  Each  word  in
              the  list  is  a  valid  argument  for  the --oo option to the sseett
              builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  The options
              appearing  in  SSHHEELLLLOOPPTTSS are those reported as _o_n by sseett --oo.  If
              this variable is in the environment when bbaasshh  starts  up,  each
              shell  option  in  the  list  will be enabled before reading any
              startup files.  This variable is read-only.
       SSHHLLVVLL  Incremented by one each time an instance of bbaasshh is started.
       UUIIDD    Expands to the user ID of the current user, initialized at shell
              startup.  This variable is readonly.

       The  following  variables  are  used by the shell.  In some cases, bbaasshh
       assigns a default value to a variable; these cases are noted below.

       BBAASSHH__CCOOMMPPAATT
              The value is used to set the shell's compatibility  level.   See
              the  description  of the sshhoopptt builtin below under SSHHEELLLL BBUUIILLTTIINN
              CCOOMMMMAANNDDSS for a description of the various  compatibility  levels
              and  their  effects.   The  value may be a decimal number (e.g.,
              4.2) or an integer (e.g., 42) corresponding to the desired  com-
              patibility  level.   If BBAASSHH__CCOOMMPPAATT is unset or set to the empty
              string, the compatibility level is set to the  default  for  the
              current  version.   If BBAASSHH__CCOOMMPPAATT is set to a value that is not
              one of the valid compatibility levels, the shell prints an error
              message  and sets the compatibility level to the default for the
              current version.  The valid compatibility levels  correspond  to
              the   compatibility   options  accepted  by  the  sshhoopptt  builtin
              described below (for example, ccoommppaatt4422 means that 4.2 and 42 are
              valid values).  The current version is also a valid value.
       BBAASSHH__EENNVV
              If  this parameter is set when bbaasshh is executing a shell script,
              its value is interpreted as a filename  containing  commands  to
              initialize the shell, as in _~_/_._b_a_s_h_r_c.  The value of BBAASSHH__EENNVV is
              subjected to  parameter  expansion,  command  substitution,  and
              arithmetic  expansion  before  being  interpreted as a filename.
              PPAATTHH is not used to search for the resultant filename.
       BBAASSHH__XXTTRRAACCEEFFDD
              If set to an integer corresponding to a valid  file  descriptor,
              bbaasshh  will  write  the  trace  output  generated  when _s_e_t _-_x is
              enabled to that file descriptor.  The file descriptor is  closed
              when  BBAASSHH__XXTTRRAACCEEFFDD is unset or assigned a new value.  Unsetting
              BBAASSHH__XXTTRRAACCEEFFDD or assigning it the empty string causes the  trace
              output  to  be  sent  to  the standard error.  Note that setting
              BBAASSHH__XXTTRRAACCEEFFDD to 2 (the standard error file descriptor) and then
              unsetting it will result in the standard error being closed.
       CCDDPPAATTHH The  search  path for the ccdd command.  This is a colon-separated
              list of directories in which the  shell  looks  for  destination
              directories  specified  by  the  ccdd  command.  A sample value is
              ".:~:/usr".
       CCHHIILLDD__MMAAXX
              Set the number of exited child status values for  the  shell  to
              remember.   Bash will not allow this value to be decreased below
              a POSIX-mandated minimum, and there is  a  maximum  value  (cur-
              rently  8192)  that  this  may not exceed.  The minimum value is
              system-dependent.
       CCOOLLUUMMNNSS
              Used by the sseelleecctt compound command to  determine  the  terminal
              width  when  printing selection lists.  Automatically set if the
              cchheecckkwwiinnssiizzee option is enabled or in an interactive  shell  upon
              receipt of a SSIIGGWWIINNCCHH.
       CCOOMMPPRREEPPLLYY
              An array variable from which bbaasshh reads the possible completions
              generated by a shell function invoked by the  programmable  com-
              pletion  facility  (see  PPrrooggrraammmmaabbllee  CCoommpplleettiioonn  below).  Each
              array element contains one possible completion.
       EEMMAACCSS  If bbaasshh finds this variable in the environment  when  the  shell
              starts  with  value "t", it assumes that the shell is running in
              an Emacs shell buffer and disables line editing.
       EENNVV    Similar to BBAASSHH__EENNVV; used when the shell  is  invoked  in  POSIX
              mode.
       FFCCEEDDIITT The default editor for the ffcc builtin command.
       FFIIGGNNOORREE
              A  colon-separated  list  of  suffixes to ignore when performing
              filename completion (see RREEAADDLLIINNEE below).  A filename whose suf-
              fix  matches  one of the entries in FFIIGGNNOORREE is excluded from the
              list of matched filenames.  A sample value is ".o:~".
       FFUUNNCCNNEESSTT
              If set to a numeric value greater  than  0,  defines  a  maximum
              function  nesting  level.  Function invocations that exceed this
              nesting level will cause the current command to abort.
       GGLLOOBBIIGGNNOORREE
              A colon-separated list of patterns defining the set of filenames
              to be ignored by pathname expansion.  If a filename matched by a
              pathname expansion pattern also matches one of the  patterns  in
              GGLLOOBBIIGGNNOORREE, it is removed from the list of matches.
       HHIISSTTCCOONNTTRROOLL
              A  colon-separated  list  of values controlling how commands are
              saved on the history list.   If  the  list  of  values  includes
              _i_g_n_o_r_e_s_p_a_c_e,  lines  which  begin with a ssppaaccee character are not
              saved in the history list.  A value of _i_g_n_o_r_e_d_u_p_s  causes  lines
              matching the previous history entry to not be saved.  A value of
              _i_g_n_o_r_e_b_o_t_h is shorthand for _i_g_n_o_r_e_s_p_a_c_e and _i_g_n_o_r_e_d_u_p_s.  A value
              of _e_r_a_s_e_d_u_p_s causes all previous lines matching the current line
              to be removed from the history list before that line  is  saved.
              Any  value  not in the above list is ignored.  If HHIISSTTCCOONNTTRROOLL is
              unset, or does not include a valid value, all lines read by  the
              shell parser are saved on the history list, subject to the value
              of HHIISSTTIIGGNNOORREE.  The second and subsequent lines of a  multi-line
              compound  command  are  not tested, and are added to the history
              regardless of the value of HHIISSTTCCOONNTTRROOLL.
       HHIISSTTFFIILLEE
              The name of the file in which command history is saved (see HHIISS--
              TTOORRYY  below).   The default value is _~_/_._b_a_s_h___h_i_s_t_o_r_y.  If unset,
              the command history is not saved when a shell exits.
       HHIISSTTFFIILLEESSIIZZEE
              The maximum number of lines contained in the history file.  When
              this  variable  is  assigned  a value, the history file is trun-
              cated, if necessary, to contain no  more  than  that  number  of
              lines  by removing the oldest entries.  The history file is also
              truncated to this size after writing it when a shell exits.   If
              the  value  is  0,  the  history file is truncated to zero size.
              Non-numeric values and numeric values  less  than  zero  inhibit
              truncation.   The  shell  sets the default value to the value of
              HHIISSTTSSIIZZEE after reading any startup files.
       HHIISSTTIIGGNNOORREE
              A colon-separated list of patterns used to decide which  command
              lines  should  be  saved  on  the history list.  Each pattern is
              anchored at the beginning of the line and must  match  the  com-
              plete  line  (no  implicit  `**'  is  appended).  Each pattern is
              tested against the line after the checks specified  by  HHIISSTTCCOONN--
              TTRROOLL  are  applied.   In  addition  to  the normal shell pattern
              matching characters, `&&' matches the previous history line.  `&&'
              may  be  escaped  using  a  backslash;  the backslash is removed
              before attempting a match.  The second and subsequent lines of a
              multi-line compound command are not tested, and are added to the
              history regardless of the value of HHIISSTTIIGGNNOORREE.
       HHIISSTTSSIIZZEE
              The number of commands to remember in the command  history  (see
              HHIISSTTOORRYY  below).   If  the value is 0, commands are not saved in
              the history list.  Numeric values less than zero result in every
              command  being  saved  on  the history list (there is no limit).
              The shell sets the  default  value  to  500  after  reading  any
              startup files.
       HHIISSTTTTIIMMEEFFOORRMMAATT
              If  this  variable  is  set and not null, its value is used as a
              format string for _s_t_r_f_t_i_m_e(3) to print the time stamp associated
              with  each  history  entry displayed by the hhiissttoorryy builtin.  If
              this variable is set, time stamps are  written  to  the  history
              file  so they may be preserved across shell sessions.  This uses
              the history comment character  to  distinguish  timestamps  from
              other history lines.
       HHOOMMEE   The home directory of the current user; the default argument for
              the ccdd builtin command.  The value of this variable is also used
              when performing tilde expansion.
       HHOOSSTTFFIILLEE
              Contains  the  name  of  a file in the same format as _/_e_t_c_/_h_o_s_t_s
              that should be read when the shell needs to complete a hostname.
              The  list  of possible hostname completions may be changed while
              the shell is running;  the  next  time  hostname  completion  is
              attempted  after the value is changed, bbaasshh adds the contents of
              the new file to the existing list.  If HHOOSSTTFFIILLEE is set, but  has
              no  value,  or  does  not name a readable file, bbaasshh attempts to
              read _/_e_t_c_/_h_o_s_t_s to obtain the list of possible hostname  comple-
              tions.  When HHOOSSTTFFIILLEE is unset, the hostname list is cleared.
       IIFFSS    The  _I_n_t_e_r_n_a_l  _F_i_e_l_d  _S_e_p_a_r_a_t_o_r  that is used for word splitting
              after expansion and to split lines  into  words  with  the  rreeaadd
              builtin  command.   The  default  value  is  ``<space><tab><new-
              line>''.
       IIGGNNOORREEEEOOFF
              Controls the action of an interactive shell on receipt of an EEOOFF
              character as the sole input.  If set, the value is the number of
              consecutive EEOOFF characters which must  be  typed  as  the  first
              characters  on an input line before bbaasshh exits.  If the variable
              exists but does not have a numeric value, or has no  value,  the
              default  value  is  10.  If it does not exist, EEOOFF signifies the
              end of input to the shell.
       IINNPPUUTTRRCC
              The filename for  the  rreeaaddlliinnee  startup  file,  overriding  the
              default of _~_/_._i_n_p_u_t_r_c (see RREEAADDLLIINNEE below).
       LLAANNGG   Used  to  determine  the  locale  category  for any category not
              specifically selected with a variable starting with LLCC__.
       LLCC__AALLLL This variable overrides the value of  LLAANNGG  and  any  other  LLCC__
              variable specifying a locale category.
       LLCC__CCOOLLLLAATTEE
              This  variable  determines the collation order used when sorting
              the results of pathname expansion, and determines  the  behavior
              of   range   expressions,  equivalence  classes,  and  collating
              sequences within pathname expansion and pattern matching.
       LLCC__CCTTYYPPEE
              This variable determines the interpretation  of  characters  and
              the  behavior of character classes within pathname expansion and
              pattern matching.
       LLCC__MMEESSSSAAGGEESS
              This variable determines the locale used  to  translate  double-
              quoted strings preceded by a $$.
       LLCC__NNUUMMEERRIICC
              This  variable  determines  the  locale category used for number
              formatting.
       LLIINNEESS  Used by the sseelleecctt compound  command  to  determine  the  column
              length  for  printing selection lists.  Automatically set if the
              cchheecckkwwiinnssiizzee option is enabled or in an interactive  shell  upon
              receipt of a SSIIGGWWIINNCCHH.
       MMAAIILL   If  this  parameter  is  set to a file or directory name and the
              MMAAIILLPPAATTHH variable is not set,  bbaasshh  informs  the  user  of  the
              arrival  of  mail in the specified file or Maildir-format direc-
              tory.
       MMAAIILLCCHHEECCKK
              Specifies how often (in seconds)  bbaasshh  checks  for  mail.   The
              default  is  60 seconds.  When it is time to check for mail, the
              shell does so before displaying the  primary  prompt.   If  this
              variable  is  unset,  or  set  to  a  value that is not a number
              greater than or equal to zero, the shell disables mail checking.
       MMAAIILLPPAATTHH
              A colon-separated list of filenames to be checked for mail.  The
              message to be printed when mail arrives in a particular file may
              be  specified by separating the filename from the message with a
              `?'.  When used in the text of the message, $$__  expands  to  the
              name of the current mailfile.  Example:
              MMAAIILLPPAATTHH='/var/mail/bfox?"You  have  mail":~/shell-mail?"$_  has
              mail!"'
              BBaasshh supplies a default value for this variable, but  the  loca-
              tion  of  the  user  mail files that it uses is system dependent
              (e.g., /var/mail/$$UUSSEERR).
       OOPPTTEERRRR If set to the value 1, bbaasshh displays error messages generated by
              the  ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).
              OOPPTTEERRRR is initialized to 1 each time the shell is invoked  or  a
              shell script is executed.
       PPAATTHH   The  search  path for commands.  It is a colon-separated list of
              directories in which the shell looks for commands  (see  CCOOMMMMAANNDD
              EEXXEECCUUTTIIOONN  below).   A  zero-length (null) directory name in the
              value of PPAATTHH indicates the current directory.  A null directory
              name  may  appear  as  two  adjacent colons, or as an initial or
              trailing colon.  The default path is  system-dependent,  and  is
              set  by  the administrator who installs bbaasshh.  A common value is
              ``/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin''.
       PPOOSSIIXXLLYY__CCOORRRREECCTT
              If  this  variable  is  in the environment when bbaasshh starts, the
              shell enters _p_o_s_i_x _m_o_d_e before reading the startup files, as  if
              the  ----ppoossiixx  invocation option had been supplied.  If it is set
              while the shell is running, bbaasshh enables _p_o_s_i_x _m_o_d_e, as  if  the
              command _s_e_t _-_o _p_o_s_i_x had been executed.
       PPRROOMMPPTT__CCOOMMMMAANNDD
              If set, the value is executed as a command prior to issuing each
              primary prompt.
       PPRROOMMPPTT__DDIIRRTTRRIIMM
              If set to a number greater than zero, the value is used  as  the
              number of trailing directory components to retain when expanding
              the \\ww and \\WW  prompt  string  escapes  (see  PPRROOMMPPTTIINNGG  below).
              Characters removed are replaced with an ellipsis.
       PPSS11    The  value  of  this parameter is expanded (see PPRROOMMPPTTIINNGG below)
              and used as the primary prompt string.   The  default  value  is
              ``\\ss--\\vv\\$$ ''.
       PPSS22    The  value of this parameter is expanded as with PPSS11 and used as
              the secondary prompt string.  The default is ``>> ''.
       PPSS33    The value of this parameter is used as the prompt for the sseelleecctt
              command (see SSHHEELLLL GGRRAAMMMMAARR above).
       PPSS44    The  value  of  this  parameter  is expanded as with PPSS11 and the
              value is printed before each command  bbaasshh  displays  during  an
              execution  trace.  The first character of PPSS44 is replicated mul-
              tiple times, as necessary, to indicate multiple levels of  indi-
              rection.  The default is ``++ ''.
       SSHHEELLLL  The full pathname to the shell is kept in this environment vari-
              able.  If it is not set when the shell starts, bbaasshh  assigns  to
              it the full pathname of the current user's login shell.
       TTIIMMEEFFOORRMMAATT
              The  value of this parameter is used as a format string specify-
              ing how the timing information for pipelines prefixed  with  the
              ttiimmee  reserved word should be displayed.  The %% character intro-
              duces an escape sequence that is expanded to  a  time  value  or
              other  information.  The escape sequences and their meanings are
              as follows; the braces denote optional portions.
              %%%%        A literal %%.
              %%[[_p]][[ll]]RR  The elapsed time in seconds.
              %%[[_p]][[ll]]UU  The number of CPU seconds spent in user mode.
              %%[[_p]][[ll]]SS  The number of CPU seconds spent in system mode.
              %%PP        The CPU percentage, computed as (%U + %S) / %R.

              The optional _p is a digit specifying the _p_r_e_c_i_s_i_o_n,  the  number
              of fractional digits after a decimal point.  A value of 0 causes
              no decimal point or fraction to be output.  At most three places
              after  the  decimal  point may be specified; values of _p greater
              than 3 are changed to 3.  If _p is not specified, the value 3  is
              used.

              The  optional ll specifies a longer format, including minutes, of
              the form _M_Mm_S_S._F_Fs.  The value of _p determines  whether  or  not
              the fraction is included.

              If  this  variable  is not set, bbaasshh acts as if it had the value
              $$''\\nnrreeaall\\tt%%33llRR\\nnuusseerr\\tt%%33llUU\\nnssyyss\\tt%%33llSS''.  If the value  is  null,
              no timing information is displayed.  A trailing newline is added
              when the format string is displayed.
       TTMMOOUUTT  If set to a value greater than zero, TTMMOOUUTT  is  treated  as  the
              default timeout for the rreeaadd builtin.  The sseelleecctt command termi-
              nates if input does not arrive after TTMMOOUUTT seconds when input is
              coming  from  a terminal.  In an interactive shell, the value is
              interpreted as the number of seconds to wait for a line of input
              after issuing the primary prompt.  BBaasshh terminates after waiting
              for that number of seconds if a complete line of input does  not
              arrive.
       TTMMPPDDIIRR If  set, bbaasshh uses its value as the name of a directory in which
              bbaasshh creates temporary files for the shell's use.
       aauuttoo__rreessuummee
              This variable controls how the shell interacts with the user and
              job  control.   If this variable is set, single word simple com-
              mands without redirections are treated as candidates for resump-
              tion of an existing stopped job.  There is no ambiguity allowed;
              if there is more than one job beginning with the  string  typed,
              the  job  most  recently  accessed  is  selected.  The _n_a_m_e of a
              stopped job, in this context, is the command line used to  start
              it.   If  set to the value _e_x_a_c_t, the string supplied must match
              the name of a stopped job exactly;  if  set  to  _s_u_b_s_t_r_i_n_g,  the
              string  supplied  needs  to  match  a substring of the name of a
              stopped job.  The _s_u_b_s_t_r_i_n_g value provides functionality  analo-
              gous  to the %%??  job identifier (see JJOOBB CCOONNTTRROOLL below).  If set
              to any other value, the supplied string must be a  prefix  of  a
              stopped job's name; this provides functionality analogous to the
              %%_s_t_r_i_n_g job identifier.
       hhiissttcchhaarrss
              The two or three characters which control history expansion  and
              tokenization (see HHIISSTTOORRYY EEXXPPAANNSSIIOONN below).  The first character
              is the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, the character which  signals
              the  start  of  a  history  expansion, normally `!!'.  The second
              character is the _q_u_i_c_k _s_u_b_s_t_i_t_u_t_i_o_n character, which is used  as
              shorthand  for  re-running the previous command entered, substi-
              tuting one string for another in the command.   The  default  is
              `^^'.   The optional third character is the character which indi-
              cates that the remainder of the line is a comment when found  as
              the  first  character of a word, normally `##'.  The history com-
              ment character causes history substitution to be skipped for the
              remaining  words on the line.  It does not necessarily cause the
              shell parser to treat the rest of the line as a comment.

   AArrrraayyss
       BBaasshh provides one-dimensional indexed and associative array  variables.
       Any  variable may be used as an indexed array; the ddeeccllaarree builtin will
       explicitly declare an array.  There is no maximum limit on the size  of
       an  array, nor any requirement that members be indexed or assigned con-
       tiguously.  Indexed arrays are  referenced  using  integers  (including
       arithmetic  expressions)   and  are  zero-based; associative arrays are
       referenced using arbitrary strings.  Unless  otherwise  noted,  indexed
       array indices must be non-negative integers.

       An  indexed  array is created automatically if any variable is assigned
       to using the syntax _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e.  The _s_u_b_s_c_r_i_p_t is treated as
       an arithmetic expression that must evaluate to a number.  To explicitly
       declare an indexed array, use ddeeccllaarree --aa _n_a_m_e (see SSHHEELLLL  BBUUIILLTTIINN  CCOOMM--
       MMAANNDDSS  below).   ddeeccllaarree  --aa _n_a_m_e[[_s_u_b_s_c_r_i_p_t]] is also accepted; the _s_u_b_-
       _s_c_r_i_p_t is ignored.

       Associative arrays are created using ddeeccllaarree --AA _n_a_m_e.

       Attributes may be specified for an array variable using the ddeeccllaarree and
       rreeaaddoonnllyy  builtins.  Each attribute applies to all members of an array.

       Arrays  are  assigned  to  using  compound  assignments  of  the   form
       _n_a_m_e=((value_1  ...  value_n)),  where  each  _v_a_l_u_e  is  of  the form [_s_u_b_-
       _s_c_r_i_p_t]=_s_t_r_i_n_g.  Indexed array assignments do not require anything  but
       _s_t_r_i_n_g.  When assigning to indexed arrays, if the optional brackets and
       subscript are supplied, that index is assigned to; otherwise the  index
       of  the element assigned is the last index assigned to by the statement
       plus one.  Indexing starts at zero.

       When assigning to an associative array, the subscript is required.

       This syntax is also accepted by the ddeeccllaarree builtin.  Individual  array
       elements  may  be  assigned  to  using the _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e syntax
       introduced above.  When assigning to an indexed array, if _n_a_m_e is  sub-
       scripted  by  a negative number, that number is interpreted as relative
       to one greater than the maximum index  of  _n_a_m_e,  so  negative  indices
       count back from the end of the array, and an index of -1 references the
       last element.

       Any element of an array may  be  referenced  using  ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}.
       The braces are required to avoid conflicts with pathname expansion.  If
       _s_u_b_s_c_r_i_p_t is @@ or **, the word expands to all members  of  _n_a_m_e.   These
       subscripts  differ only when the word appears within double quotes.  If
       the word is double-quoted, ${_n_a_m_e[*]} expands to a single word with the
       value  of each array member separated by the first character of the IIFFSS
       special variable, and ${_n_a_m_e[@]} expands each element of _n_a_m_e to a sep-
       arate  word.   When  there  are no array members, ${_n_a_m_e[@]} expands to
       nothing.  If the double-quoted expansion  occurs  within  a  word,  the
       expansion  of  the first parameter is joined with the beginning part of
       the original word, and the expansion of the last  parameter  is  joined
       with  the  last  part  of  the original word.  This is analogous to the
       expansion of the special parameters ** and  @@  (see  SSppeecciiaall  PPaarraammeetteerrss
       above).   ${#_n_a_m_e[_s_u_b_s_c_r_i_p_t]}  expands  to  the  length  of ${_n_a_m_e[_s_u_b_-
       _s_c_r_i_p_t]}.  If _s_u_b_s_c_r_i_p_t is ** or @@, the expansion is the number of  ele-
       ments  in the array.  Referencing an array variable without a subscript
       is equivalent to referencing the array with a subscript of 0.   If  the
       _s_u_b_s_c_r_i_p_t used to reference an element of an indexed array evaluates to
       a number less than zero, it is interpreted as relative to  one  greater
       than  the  maximum  index  of the array, so negative indices count back
       from the end of the array, and an index of -1 references the last  ele-
       ment.

       An  array variable is considered set if a subscript has been assigned a
       value.  The null string is a valid value.

       It is possible to obtain the keys (indices) of an array as well as  the
       values.   ${!!_n_a_m_e[_@]} and ${!!_n_a_m_e[_*]} expand to the indices assigned in
       array variable _n_a_m_e.  The treatment when in double quotes is similar to
       the expansion of the special parameters _@ and _* within double quotes.

       The  uunnsseett  builtin  is  used to destroy arrays.  uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t]
       destroys the array element at index _s_u_b_s_c_r_i_p_t.  Negative subscripts  to
       indexed  arrays are interpreted as described above.  Care must be taken
       to avoid unwanted side effects caused  by  pathname  expansion.   uunnsseett
       _n_a_m_e, where _n_a_m_e is an array, or uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t], where _s_u_b_s_c_r_i_p_t
       is ** or @@, removes the entire array.

       The ddeeccllaarree, llooccaall, and rreeaaddoonnllyy builtins each accept a  --aa  option  to
       specify  an  indexed  array  and  a --AA option to specify an associative
       array.  If both options are supplied, --AA takes  precedence.   The  rreeaadd
       builtin  accepts  a  --aa  option to assign a list of words read from the
       standard input to an array.  The sseett and ddeeccllaarree builtins display array
       values in a way that allows them to be reused as assignments.

EEXXPPAANNSSIIOONN
       Expansion is performed on the command line after it has been split into
       words.  There are seven kinds of expansion performed: _b_r_a_c_e  _e_x_p_a_n_s_i_o_n,
       _t_i_l_d_e  _e_x_p_a_n_s_i_o_n,  _p_a_r_a_m_e_t_e_r  _a_n_d _v_a_r_i_a_b_l_e _e_x_p_a_n_s_i_o_n, _c_o_m_m_a_n_d _s_u_b_s_t_i_t_u_-
       _t_i_o_n, _a_r_i_t_h_m_e_t_i_c _e_x_p_a_n_s_i_o_n, _w_o_r_d _s_p_l_i_t_t_i_n_g, and _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n.

       The order of expansions is: brace expansion; tilde expansion, parameter
       and  variable expansion, arithmetic expansion, and command substitution
       (done in a left-to-right fashion); word splitting; and pathname  expan-
       sion.

       On systems that can support it, there is an additional expansion avail-
       able: _p_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n.  This is performed  at  the  same  time  as
       tilde,  parameter,  variable, and arithmetic expansion and command sub-
       stitution.

       Only brace expansion, word splitting, and pathname expansion can change
       the  number of words of the expansion; other expansions expand a single
       word to a single word.  The only exceptions to this are the  expansions
       of "$$@@" and "$${{_n_a_m_e[[@@]]}}" as explained above (see PPAARRAAMMEETTEERRSS).

   BBrraaccee EExxppaannssiioonn
       _B_r_a_c_e _e_x_p_a_n_s_i_o_n is a mechanism by which arbitrary strings may be gener-
       ated.  This mechanism is similar to _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n, but  the  file-
       names generated need not exist.  Patterns to be brace expanded take the
       form of an optional _p_r_e_a_m_b_l_e, followed by either a series of comma-sep-
       arated  strings or a sequence expression between a pair of braces, fol-
       lowed by an optional _p_o_s_t_s_c_r_i_p_t.  The  preamble  is  prefixed  to  each
       string contained within the braces, and the postscript is then appended
       to each resulting string, expanding left to right.

       Brace expansions may be nested.  The results of  each  expanded  string
       are  not  sorted;  left  to  right  order  is  preserved.  For example,
       a{{d,c,b}}e expands into `ade ace abe'.

       A sequence expression takes the form {{_x...._y[[...._i_n_c_r]]}}, where _x and _y  are
       either  integers or single characters, and _i_n_c_r, an optional increment,
       is an integer.  When integers are supplied, the expression  expands  to
       each  number between _x and _y, inclusive.  Supplied integers may be pre-
       fixed with _0 to force each term to have the same width.  When either  _x
       or  _y  begins  with  a  zero, the shell attempts to force all generated
       terms to contain the same number of digits, zero-padding  where  neces-
       sary.   When  characters  are  supplied, the expression expands to each
       character lexicographically between  _x  and  _y,  inclusive,  using  the
       default  C  locale.   Note  that both _x and _y must be of the same type.
       When the increment is supplied, it is used as  the  difference  between
       each term.  The default increment is 1 or -1 as appropriate.

       Brace expansion is performed before any other expansions, and any char-
       acters special to other expansions are preserved in the result.  It  is
       strictly  textual.  BBaasshh does not apply any syntactic interpretation to
       the context of the expansion or the text between the braces.

       A correctly-formed brace expansion must contain  unquoted  opening  and
       closing  braces,  and  at  least one unquoted comma or a valid sequence
       expression.  Any incorrectly formed brace expansion is left  unchanged.
       A {{ or ,, may be quoted with a backslash to prevent its being considered
       part of a brace expression.  To avoid conflicts with  parameter  expan-
       sion, the string $${{ is not considered eligible for brace expansion.

       This construct is typically used as shorthand when the common prefix of
       the strings to be generated is longer than in the above example:

              mkdir /usr/local/src/bash/{old,new,dist,bugs}
       or
              chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}

       Brace expansion introduces a  slight  incompatibility  with  historical
       versions  of sshh.  sshh does not treat opening or closing braces specially
       when they appear as part of a word, and preserves them in  the  output.
       BBaasshh  removes  braces  from  words as a consequence of brace expansion.
       For example, a word entered to sshh as _f_i_l_e_{_1_,_2_} appears  identically  in
       the  output.  The same word is output as _f_i_l_e_1 _f_i_l_e_2 after expansion by
       bbaasshh.  If strict compatibility with sshh is desired, start bbaasshh with  the
       ++BB option or disable brace expansion with the ++BB option to the sseett com-
       mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).

   TTiillddee EExxppaannssiioonn
       If a word begins with an unquoted tilde character  (`~~'),  all  of  the
       characters  preceding  the  first unquoted slash (or all characters, if
       there is no unquoted slash) are considered a _t_i_l_d_e_-_p_r_e_f_i_x.  If none  of
       the  characters  in  the tilde-prefix are quoted, the characters in the
       tilde-prefix following the tilde are treated as a possible _l_o_g_i_n  _n_a_m_e.
       If  this  login name is the null string, the tilde is replaced with the
       value of the shell parameter HHOOMMEE.  If HHOOMMEE is unset, the  home  direc-
       tory  of  the  user executing the shell is substituted instead.  Other-
       wise, the tilde-prefix is replaced with the home  directory  associated
       with the specified login name.

       If  the  tilde-prefix  is  a  `~+', the value of the shell variable PPWWDD
       replaces the tilde-prefix.  If the tilde-prefix is a `~-', the value of
       the  shell variable OOLLDDPPWWDD, if it is set, is substituted.  If the char-
       acters following the tilde in the tilde-prefix consist of a  number  _N,
       optionally  prefixed  by  a  `+' or a `-', the tilde-prefix is replaced
       with the corresponding element from the directory stack, as it would be
       displayed by the ddiirrss builtin invoked with the tilde-prefix as an argu-
       ment.  If the characters following the tilde in the  tilde-prefix  con-
       sist of a number without a leading `+' or `-', `+' is assumed.

       If the login name is invalid, or the tilde expansion fails, the word is
       unchanged.

       Each variable assignment is checked for unquoted tilde-prefixes immedi-
       ately following a :: or the first ==.  In these cases, tilde expansion is
       also performed.  Consequently, one may use  filenames  with  tildes  in
       assignments  to  PPAATTHH,  MMAAIILLPPAATTHH, and CCDDPPAATTHH, and the shell assigns the
       expanded value.

   PPaarraammeetteerr EExxppaannssiioonn
       The `$$' character introduces parameter expansion, command substitution,
       or  arithmetic  expansion.  The parameter name or symbol to be expanded
       may be enclosed in braces, which are optional but serve to protect  the
       variable  to be expanded from characters immediately following it which
       could be interpreted as part of the name.

       When braces are used, the matching ending brace is the  first  `}}'  not
       escaped  by  a  backslash  or within a quoted string, and not within an
       embedded  arithmetic  expansion,  command  substitution,  or  parameter
       expansion.

       ${_p_a_r_a_m_e_t_e_r}
              The  value of _p_a_r_a_m_e_t_e_r is substituted.  The braces are required
              when _p_a_r_a_m_e_t_e_r is a positional  parameter  with  more  than  one
              digit, or when _p_a_r_a_m_e_t_e_r is followed by a character which is not
              to be interpreted as part of its name.  The _p_a_r_a_m_e_t_e_r is a shell
              parameter  as  described above PPAARRAAMMEETTEERRSS) or an array reference
              (AArrrraayyss).

       If the first character of _p_a_r_a_m_e_t_e_r is an  exclamation  point  (!!),  it
       introduces a level of variable indirection.  BBaasshh uses the value of the
       variable formed from the rest of _p_a_r_a_m_e_t_e_r as the name of the variable;
       this  variable  is  then expanded and that value is used in the rest of
       the substitution, rather than the value of _p_a_r_a_m_e_t_e_r itself.   This  is
       known as _i_n_d_i_r_e_c_t _e_x_p_a_n_s_i_o_n.  The exceptions to this are the expansions
       of ${!!_p_r_e_f_i_x**} and ${!!_n_a_m_e[_@]} described below.  The exclamation  point
       must  immediately  follow the left brace in order to introduce indirec-
       tion.

       In each of the cases below, _w_o_r_d is subject to tilde expansion, parame-
       ter expansion, command substitution, and arithmetic expansion.

       When  not  performing  substring  expansion, using the forms documented
       below (e.g., ::--), bbaasshh tests for a parameter that  is  unset  or  null.
       Omitting  the  colon  results  in  a  test only for a parameter that is
       unset.

       ${_p_a_r_a_m_e_t_e_r::--_w_o_r_d}
              UUssee DDeeffaauulltt VVaalluueess.  If _p_a_r_a_m_e_t_e_r is unset or null,  the  expan-
              sion  of _w_o_r_d is substituted.  Otherwise, the value of _p_a_r_a_m_e_t_e_r
              is substituted.
       ${_p_a_r_a_m_e_t_e_r::==_w_o_r_d}
              AAssssiiggnn DDeeffaauulltt VVaalluueess.  If  _p_a_r_a_m_e_t_e_r  is  unset  or  null,  the
              expansion of _w_o_r_d is assigned to _p_a_r_a_m_e_t_e_r.  The value of _p_a_r_a_m_-
              _e_t_e_r is then substituted.   Positional  parameters  and  special
              parameters may not be assigned to in this way.
       ${_p_a_r_a_m_e_t_e_r::??_w_o_r_d}
              DDiissppllaayy  EErrrroorr iiff NNuullll oorr UUnnsseett.  If _p_a_r_a_m_e_t_e_r is null or unset,
              the expansion of _w_o_r_d (or a message to that effect  if  _w_o_r_d  is
              not  present) is written to the standard error and the shell, if
              it is not interactive, exits.  Otherwise, the value of _p_a_r_a_m_e_t_e_r
              is substituted.
       ${_p_a_r_a_m_e_t_e_r::++_w_o_r_d}
              UUssee  AAlltteerrnnaattee VVaalluuee.  If _p_a_r_a_m_e_t_e_r is null or unset, nothing is
              substituted, otherwise the expansion of _w_o_r_d is substituted.
       ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t}
       ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t::_l_e_n_g_t_h}
              SSuubbssttrriinngg EExxppaannssiioonn.  Expands to up to _l_e_n_g_t_h characters of  the
              value  of  _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_-
              _s_e_t.  If _p_a_r_a_m_e_t_e_r is @@, an indexed array subscripted by @@ or **,
              or  an  associative  array name, the results differ as described
              below.  If _l_e_n_g_t_h is omitted, expands to the  substring  of  the
              value of _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_s_e_t
              and extending to the end of the value.  _l_e_n_g_t_h  and  _o_f_f_s_e_t  are
              arithmetic expressions (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN below).

              If  _o_f_f_s_e_t  evaluates  to  a number less than zero, the value is
              used as an offset in characters from the end  of  the  value  of
              _p_a_r_a_m_e_t_e_r.   If  _l_e_n_g_t_h evaluates to a number less than zero, it
              is interpreted as an offset in characters from the  end  of  the
              value  of  _p_a_r_a_m_e_t_e_r rather than a number of characters, and the
              expansion is the characters  between  _o_f_f_s_e_t  and  that  result.
              Note  that a negative offset must be separated from the colon by
              at least one space to avoid being confused with  the  ::--  expan-
              sion.

              If  _p_a_r_a_m_e_t_e_r  is  @@, the result is _l_e_n_g_t_h positional parameters
              beginning at _o_f_f_s_e_t.  A negative _o_f_f_s_e_t is taken relative to one
              greater  than the greatest positional parameter, so an offset of
              -1 evaluates to the last positional parameter.  It is an  expan-
              sion error if _l_e_n_g_t_h evaluates to a number less than zero.

              If _p_a_r_a_m_e_t_e_r is an indexed array name subscripted by @ or *, the
              result is  the  _l_e_n_g_t_h  members  of  the  array  beginning  with
              ${_p_a_r_a_m_e_t_e_r[_o_f_f_s_e_t]}.   A  negative  _o_f_f_s_e_t is taken relative to
              one greater than the maximum index of the specified  array.   It
              is  an expansion error if _l_e_n_g_t_h evaluates to a number less than
              zero.

              Substring expansion applied to  an  associative  array  produces
              undefined results.

              Substring  indexing  is zero-based unless the positional parame-
              ters are used, in  which  case  the  indexing  starts  at  1  by
              default.   If  _o_f_f_s_e_t  is  0,  and the positional parameters are
              used, $$00 is prefixed to the list.

       ${!!_p_r_e_f_i_x**}
       ${!!_p_r_e_f_i_x@@}
              NNaammeess mmaattcchhiinngg pprreeffiixx.  Expands to the names of variables  whose
              names begin with _p_r_e_f_i_x, separated by the first character of the
              IIFFSS special variable.  When _@ is used and the expansion  appears
              within  double  quotes, each variable name expands to a separate
              word.

       ${!!_n_a_m_e[_@]}
       ${!!_n_a_m_e[_*]}
              LLiisstt ooff aarrrraayy kkeeyyss.  If _n_a_m_e is an array  variable,  expands  to
              the  list  of array indices (keys) assigned in _n_a_m_e.  If _n_a_m_e is
              not an array, expands to 0 if _n_a_m_e is set  and  null  otherwise.
              When  _@  is used and the expansion appears within double quotes,
              each key expands to a separate word.

       ${##_p_a_r_a_m_e_t_e_r}
              PPaarraammeetteerr lleennggtthh.  The length in  characters  of  the  value  of
              _p_a_r_a_m_e_t_e_r  is  substituted.   If  _p_a_r_a_m_e_t_e_r is ** or @@, the value
              substituted is the number of positional parameters.  If  _p_a_r_a_m_e_-
              _t_e_r  is  an  array name subscripted by ** or @@, the value substi-
              tuted is the number of elements in the array.  If  _p_a_r_a_m_e_t_e_r  is
              an  indexed  array  name  subscripted by a negative number, that
              number is interpreted as relative to one greater than the  maxi-
              mum  index of _p_a_r_a_m_e_t_e_r, so negative indices count back from the
              end of the array, and an index of -1 references  the  last  ele-
              ment.

       ${_p_a_r_a_m_e_t_e_r##_w_o_r_d}
       ${_p_a_r_a_m_e_t_e_r####_w_o_r_d}
              RReemmoovvee mmaattcchhiinngg pprreeffiixx ppaatttteerrnn.  The _w_o_r_d is expanded to produce
              a pattern just as in pathname expansion.  If the pattern matches
              the  beginning of the value of _p_a_r_a_m_e_t_e_r, then the result of the
              expansion is the expanded value of _p_a_r_a_m_e_t_e_r with  the  shortest
              matching  pattern  (the ``##'' case) or the longest matching pat-
              tern (the ``####'' case) deleted.  If _p_a_r_a_m_e_t_e_r is  @@  or  **,  the
              pattern  removal operation is applied to each positional parame-
              ter in turn, and the expansion is the resultant list.  If _p_a_r_a_m_-
              _e_t_e_r  is  an array variable subscripted with @@ or **, the pattern
              removal operation is applied to each  member  of  the  array  in
              turn, and the expansion is the resultant list.

       ${_p_a_r_a_m_e_t_e_r%%_w_o_r_d}
       ${_p_a_r_a_m_e_t_e_r%%%%_w_o_r_d}
              RReemmoovvee mmaattcchhiinngg ssuuffffiixx ppaatttteerrnn.  The _w_o_r_d is expanded to produce
              a pattern just as in pathname expansion.  If the pattern matches
              a  trailing portion of the expanded value of _p_a_r_a_m_e_t_e_r, then the
              result of the expansion is the expanded value of _p_a_r_a_m_e_t_e_r  with
              the  shortest  matching  pattern (the ``%%'' case) or the longest
              matching pattern (the ``%%%%'' case) deleted.  If _p_a_r_a_m_e_t_e_r  is  @@
              or  **,  the  pattern  removal operation is applied to each posi-
              tional parameter in turn, and the  expansion  is  the  resultant
              list.   If  _p_a_r_a_m_e_t_e_r is an array variable subscripted with @@ or
              **, the pattern removal operation is applied to  each  member  of
              the array in turn, and the expansion is the resultant list.

       ${_p_a_r_a_m_e_t_e_r//_p_a_t_t_e_r_n//_s_t_r_i_n_g}
              PPaatttteerrnn ssuubbssttiittuuttiioonn.  The _p_a_t_t_e_r_n is expanded to produce a pat-
              tern just as in pathname expansion.  _P_a_r_a_m_e_t_e_r is  expanded  and
              the  longest match of _p_a_t_t_e_r_n against its value is replaced with
              _s_t_r_i_n_g.  If _p_a_t_t_e_r_n begins with //, all matches  of  _p_a_t_t_e_r_n  are
              replaced   with  _s_t_r_i_n_g.   Normally  only  the  first  match  is
              replaced.  If _p_a_t_t_e_r_n begins with ##, it must match at the begin-
              ning of the expanded value of _p_a_r_a_m_e_t_e_r.  If _p_a_t_t_e_r_n begins with
              %%, it must match at the end of the expanded value of  _p_a_r_a_m_e_t_e_r.
              If _s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are deleted and the // fol-
              lowing _p_a_t_t_e_r_n may be omitted.  If _p_a_r_a_m_e_t_e_r is @@ or **, the sub-
              stitution  operation  is applied to each positional parameter in
              turn, and the expansion is the resultant list.  If _p_a_r_a_m_e_t_e_r  is
              an  array  variable  subscripted  with  @@ or **, the substitution
              operation is applied to each member of the array  in  turn,  and
              the expansion is the resultant list.

       ${_p_a_r_a_m_e_t_e_r^^_p_a_t_t_e_r_n}
       ${_p_a_r_a_m_e_t_e_r^^^^_p_a_t_t_e_r_n}
       ${_p_a_r_a_m_e_t_e_r,,_p_a_t_t_e_r_n}
       ${_p_a_r_a_m_e_t_e_r,,,,_p_a_t_t_e_r_n}
              CCaassee  mmooddiiffiiccaattiioonn.   This expansion modifies the case of alpha-
              betic characters in _p_a_r_a_m_e_t_e_r.  The _p_a_t_t_e_r_n is expanded to  pro-
              duce a pattern just as in pathname expansion.  Each character in
              the expanded value of _p_a_r_a_m_e_t_e_r is tested against _p_a_t_t_e_r_n,  and,
              if  it  matches the pattern, its case is converted.  The pattern
              should not attempt to match more  than  one  character.   The  ^^
              operator  converts  lowercase letters matching _p_a_t_t_e_r_n to upper-
              case; the ,, operator converts matching uppercase letters to low-
              ercase.  The ^^^^ and ,,,, expansions convert each matched character
              in the expanded value; the ^^ and ,, expansions match and  convert
              only  the  first character in the expanded value.  If _p_a_t_t_e_r_n is
              omitted, it is treated like a ??, which matches every  character.
              If  _p_a_r_a_m_e_t_e_r  is  @@  or  **,  the case modification operation is
              applied to each positional parameter in turn, and the  expansion
              is  the  resultant list.  If _p_a_r_a_m_e_t_e_r is an array variable sub-
              scripted with @@ or **, the case modification operation is applied
              to  each  member  of the array in turn, and the expansion is the
              resultant list.

   CCoommmmaanndd SSuubbssttiittuuttiioonn
       _C_o_m_m_a_n_d _s_u_b_s_t_i_t_u_t_i_o_n allows the output of a command to replace the com-
       mand name.  There are two forms:

              $$((_c_o_m_m_a_n_d))
       or
              ``_c_o_m_m_a_n_d``

       BBaasshh performs the expansion by executing _c_o_m_m_a_n_d and replacing the com-
       mand substitution with the standard output of  the  command,  with  any
       trailing newlines deleted.  Embedded newlines are not deleted, but they
       may be removed during word splitting.  The command  substitution  $$((ccaatt
       _f_i_l_e)) can be replaced by the equivalent but faster $$((<< _f_i_l_e)).

       When  the  old-style  backquote form of substitution is used, backslash
       retains its literal meaning except when followed by $$, ``,  or  \\.   The
       first backquote not preceded by a backslash terminates the command sub-
       stitution.  When using the $(_c_o_m_m_a_n_d) form, all characters between  the
       parentheses make up the command; none are treated specially.

       Command substitutions may be nested.  To nest when using the backquoted
       form, escape the inner backquotes with backslashes.

       If the substitution appears within double quotes,  word  splitting  and
       pathname expansion are not performed on the results.

   AArriitthhmmeettiicc EExxppaannssiioonn
       Arithmetic  expansion allows the evaluation of an arithmetic expression
       and the substitution of the result.  The format for  arithmetic  expan-
       sion is:

              $$((((_e_x_p_r_e_s_s_i_o_n))))

       The  _e_x_p_r_e_s_s_i_o_n  is  treated  as if it were within double quotes, but a
       double quote inside the parentheses  is  not  treated  specially.   All
       tokens in the expression undergo parameter and variable expansion, com-
       mand substitution, and quote removal.  The result  is  treated  as  the
       arithmetic  expression  to  be evaluated.  Arithmetic expansions may be
       nested.

       The evaluation is performed according to the rules listed  below  under
       AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN.  If _e_x_p_r_e_s_s_i_o_n is invalid, bbaasshh prints a message
       indicating failure and no substitution occurs.

   PPrroocceessss SSuubbssttiittuuttiioonn
       _P_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n is supported on systems that support  named  pipes
       (_F_I_F_O_s)  or the //ddeevv//ffdd method of naming open files.  It takes the form
       of <<((_l_i_s_t)) or >>((_l_i_s_t)).  The process _l_i_s_t is run with its input or  out-
       put connected to a _F_I_F_O or some file in //ddeevv//ffdd.  The name of this file
       is passed as an argument to the current command as the  result  of  the
       expansion.   If the >>((_l_i_s_t)) form is used, writing to the file will pro-
       vide input for _l_i_s_t.  If the <<((_l_i_s_t)) form is used, the file  passed  as
       an argument should be read to obtain the output of _l_i_s_t.

       When  available,  process substitution is performed simultaneously with
       parameter and variable expansion, command substitution, and  arithmetic
       expansion.

   WWoorrdd SSpplliittttiinngg
       The  shell  scans the results of parameter expansion, command substitu-
       tion, and arithmetic expansion that did not occur within double  quotes
       for _w_o_r_d _s_p_l_i_t_t_i_n_g.

       The  shell  treats each character of IIFFSS as a delimiter, and splits the
       results of the other expansions into words using  these  characters  as
       field   terminators.   If  IIFFSS  is  unset,  or  its  value  is  exactly
       <<ssppaaccee>><<ttaabb>><<nneewwlliinnee>>, the default, then sequences of  <<ssppaaccee>>,  <<ttaabb>>,
       and  <<nneewwlliinnee>>  at the beginning and end of the results of the previous
       expansions are ignored, and any sequence of IIFFSS characters not  at  the
       beginning  or  end  serves  to delimit words.  If IIFFSS has a value other
       than the default, then sequences of the whitespace characters ssppaaccee and
       ttaabb  are  ignored  at the beginning and end of the word, as long as the
       whitespace character is in the value of IIFFSS (an IIFFSS whitespace  charac-
       ter).   Any character in IIFFSS that is not IIFFSS whitespace, along with any
       adjacent IIFFSS whitespace characters, delimits a field.   A  sequence  of
       IIFFSS whitespace characters is also treated as a delimiter.  If the value
       of IIFFSS is null, no word splitting occurs.

       Explicit null arguments ("""" or '''')  are  retained.   Unquoted  implicit
       null arguments, resulting from the expansion of parameters that have no
       values, are removed.  If a parameter with no value is  expanded  within
       double quotes, a null argument results and is retained.

       Note that if no expansion occurs, no splitting is performed.

   PPaatthhnnaammee EExxppaannssiioonn
       After  word  splitting,  unless  the --ff option has been set, bbaasshh scans
       each word for the characters **, ??, and [[.  If one of  these  characters
       appears,  then  the word is regarded as a _p_a_t_t_e_r_n, and replaced with an
       alphabetically sorted list of filenames matching the pattern (see  PPaatt--
       tteerrnn  MMaattcchhiinngg  below).   If  no  matching filenames are found, and the
       shell option nnuullllgglloobb is not enabled, the word is left  unchanged.   If
       the  nnuullllgglloobb  option  is  set,  and  no matches are found, the word is
       removed.  If the ffaaiillgglloobb shell option  is  set,  and  no  matches  are
       found, an error message is printed and the command is not executed.  If
       the shell option nnooccaasseegglloobb is enabled, the match is performed  without
       regard  to  the  case of alphabetic characters.  When a pattern is used
       for pathname expansion, the character ````..''''  at the start of a name  or
       immediately  following  a  slash must be matched explicitly, unless the
       shell option ddoottgglloobb is set.  When matching a pathname, the slash char-
       acter  must  always  be  matched explicitly.  In other cases, the ````..''''
       character is not treated specially.  See the description of sshhoopptt below
       under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS for a description of the nnooccaasseegglloobb, nnuullll--
       gglloobb, ffaaiillgglloobb, and ddoottgglloobb shell options.

       The GGLLOOBBIIGGNNOORREE shell variable may be used to restrict the set of  file-
       names matching a _p_a_t_t_e_r_n.  If GGLLOOBBIIGGNNOORREE is set, each matching filename
       that also matches one of the patterns in GGLLOOBBIIGGNNOORREE is removed from the
       list  of  matches.  The filenames ````..''''  and ````....''''  are always ignored
       when GGLLOOBBIIGGNNOORREE is set and not null.  However, setting GGLLOOBBIIGGNNOORREE to  a
       non-null  value has the effect of enabling the ddoottgglloobb shell option, so
       all other filenames beginning with a ````..''''  will match.  To get the old
       behavior of ignoring filenames beginning with a ````..'''', make ````..**''''  one
       of the patterns in GGLLOOBBIIGGNNOORREE.  The ddoottgglloobb  option  is  disabled  when
       GGLLOOBBIIGGNNOORREE is unset.

       PPaatttteerrnn MMaattcchhiinngg

       Any character that appears in a pattern, other than the special pattern
       characters described below, matches itself.  The NUL character may  not
       occur  in  a pattern.  A backslash escapes the following character; the
       escaping backslash is discarded when  matching.   The  special  pattern
       characters must be quoted if they are to be matched literally.

       The special pattern characters have the following meanings:

              **      Matches  any string, including the null string.  When the
                     gglloobbssttaarr shell option is enabled, and  **  is  used  in  a
                     pathname  expansion  context,  two  adjacent **s used as a
                     single pattern will match all  files  and  zero  or  more
                     directories  and subdirectories.  If followed by a //, two
                     adjacent **s will match only directories  and  subdirecto-
                     ries.
              ??      Matches any single character.
              [[......]]  Matches  any  one  of the enclosed characters.  A pair of
                     characters separated by a hyphen denotes a _r_a_n_g_e  _e_x_p_r_e_s_-
                     _s_i_o_n;  any character that falls between those two charac-
                     ters, inclusive, using  the  current  locale's  collating
                     sequence  and  character  set,  is matched.  If the first
                     character following the [[ is a !!  or a ^^ then any charac-
                     ter  not enclosed is matched.  The sorting order of char-
                     acters in range expressions is determined by the  current
                     locale  and  the values of the LLCC__CCOOLLLLAATTEE or LLCC__AALLLL shell
                     variables, if set.  To obtain the traditional interpreta-
                     tion  of  range expressions, where [[aa--dd]] is equivalent to
                     [[aabbccdd]], set value of the LLCC__AALLLL shell variable to  CC,  or
                     enable  the  gglloobbaasscciiiirraannggeess  shell  option.   A -- may be
                     matched by including it as the first or last character in
                     the set.  A ]] may be matched by including it as the first
                     character in the set.

                     Within [[ and ]], _c_h_a_r_a_c_t_e_r _c_l_a_s_s_e_s can be specified  using
                     the syntax [[::_c_l_a_s_s::]], where _c_l_a_s_s is one of the following
                     classes defined in the POSIX standard:
                     aallnnuumm aallpphhaa aasscciiii bbllaannkk ccnnttrrll  ddiiggiitt  ggrraapphh  lloowweerr  pprriinntt
                     ppuunncctt ssppaaccee uuppppeerr wwoorrdd xxddiiggiitt
                     A character class matches any character belonging to that
                     class.  The wwoorrdd character class matches letters, digits,
                     and the character _.

                     Within  [[  and  ]],  an _e_q_u_i_v_a_l_e_n_c_e _c_l_a_s_s can be specified
                     using the syntax [[==_c==]], which matches all characters with
                     the  same  collation  weight  (as  defined by the current
                     locale) as the character _c.

                     Within [[ and ]], the syntax [[.._s_y_m_b_o_l..]] matches the collat-
                     ing symbol _s_y_m_b_o_l.

       If the eexxttgglloobb shell option is enabled using the sshhoopptt builtin, several
       extended pattern matching operators are recognized.  In  the  following
       description, a _p_a_t_t_e_r_n_-_l_i_s_t is a list of one or more patterns separated
       by a ||.  Composite patterns may be formed using one or more of the fol-
       lowing sub-patterns:

              ??((_p_a_t_t_e_r_n_-_l_i_s_t))
                     Matches zero or one occurrence of the given patterns
              **((_p_a_t_t_e_r_n_-_l_i_s_t))
                     Matches zero or more occurrences of the given patterns
              ++((_p_a_t_t_e_r_n_-_l_i_s_t))
                     Matches one or more occurrences of the given patterns
              @@((_p_a_t_t_e_r_n_-_l_i_s_t))
                     Matches one of the given patterns
              !!((_p_a_t_t_e_r_n_-_l_i_s_t))
                     Matches anything except one of the given patterns

   QQuuoottee RReemmoovvaall
       After the preceding expansions, all unquoted occurrences of the charac-
       ters \\, '', and "" that did not result from one of the  above  expansions
       are removed.

RREEDDIIRREECCTTIIOONN
       Before  a  command  is executed, its input and output may be _r_e_d_i_r_e_c_t_e_d
       using a special notation interpreted by the shell.  Redirection  allows
       commands'  file handles to be duplicated, opened, closed, made to refer
       to different files, and can change the files the command reads from and
       writes  to.  Redirection may also be used to modify file handles in the
       current shell execution environment.  The following redirection  opera-
       tors may precede or appear anywhere within a _s_i_m_p_l_e _c_o_m_m_a_n_d or may fol-
       low a _c_o_m_m_a_n_d.  Redirections are processed in the  order  they  appear,
       from left to right.

       Each  redirection  that may be preceded by a file descriptor number may
       instead be preceded by a word of the form {_v_a_r_n_a_m_e}.  In this case, for
       each redirection operator except >&- and <&-, the shell will allocate a
       file descriptor greater than or equal to 10 and assign it  to  _v_a_r_n_a_m_e.
       If  >&-  or  <&- is preceded by {_v_a_r_n_a_m_e}, the value of _v_a_r_n_a_m_e defines
       the file descriptor to close.

       In the following descriptions, if the file descriptor number  is  omit-
       ted,  and the first character of the redirection operator is <<, the re-
       direction refers to the standard input (file  descriptor  0).   If  the
       first  character  of  the  redirection  operator  is >>, the redirection
       refers to the standard output (file descriptor 1).

       The word following the redirection operator in the  following  descrip-
       tions,  unless  otherwise noted, is subjected to brace expansion, tilde
       expansion, parameter  and  variable  expansion,  command  substitution,
       arithmetic  expansion,  quote  removal,  pathname  expansion,  and word
       splitting.  If it expands to more than one word, bbaasshh reports an error.

       Note  that  the order of redirections is significant.  For example, the
       command

              ls >> dirlist 2>>&&1

       directs both standard output and standard error to  the  file  _d_i_r_l_i_s_t,
       while the command

              ls 2>>&&1 >> dirlist

       directs  only the standard output to file _d_i_r_l_i_s_t, because the standard
       error was duplicated from the standard output before the standard  out-
       put was redirected to _d_i_r_l_i_s_t.

       BBaasshh handles several filenames specially when they are used in redirec-
       tions, as described in the following table:

              //ddeevv//ffdd//_f_d
                     If _f_d is a valid integer, file descriptor  _f_d  is  dupli-
                     cated.
              //ddeevv//ssttddiinn
                     File descriptor 0 is duplicated.
              //ddeevv//ssttddoouutt
                     File descriptor 1 is duplicated.
              //ddeevv//ssttddeerrrr
                     File descriptor 2 is duplicated.
              //ddeevv//ttccpp//_h_o_s_t//_p_o_r_t
                     If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t
                     is an integer port number or service name, bbaasshh  attempts
                     to open the corresponding TCP socket.
              //ddeevv//uuddpp//_h_o_s_t//_p_o_r_t
                     If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t
                     is an integer port number or service name, bbaasshh  attempts
                     to open the corresponding UDP socket.

       A failure to open or create a file causes the redirection to fail.

       Redirections  using file descriptors greater than 9 should be used with
       care, as they may conflict with file descriptors the shell uses  inter-
       nally.

   RReeddiirreeccttiinngg IInnppuutt
       Redirection of input causes the file whose name results from the expan-
       sion of _w_o_r_d to be opened for reading on  file  descriptor  _n,  or  the
       standard input (file descriptor 0) if _n is not specified.

       The general format for redirecting input is:

              [_n]<<_w_o_r_d

   RReeddiirreeccttiinngg OOuuttppuutt
       Redirection  of  output  causes  the  file  whose name results from the
       expansion of _w_o_r_d to be opened for writing on file descriptor _n, or the
       standard output (file descriptor 1) if _n is not specified.  If the file
       does not exist it is created; if it does exist it is truncated to  zero
       size.

       The general format for redirecting output is:

              [_n]>>_w_o_r_d

       If  the  redirection operator is >>, and the nnoocclloobbbbeerr option to the sseett
       builtin has been enabled, the redirection will fail if the  file  whose
       name  results  from the expansion of _w_o_r_d exists and is a regular file.
       If the redirection operator is >>||, or the redirection operator is >> and
       the nnoocclloobbbbeerr option to the sseett builtin command is not enabled, the re-
       direction is attempted even if the file named by _w_o_r_d exists.

   AAppppeennddiinngg RReeddiirreecctteedd OOuuttppuutt
       Redirection of output in  this  fashion  causes  the  file  whose  name
       results  from  the expansion of _w_o_r_d to be opened for appending on file
       descriptor _n, or the standard output (file descriptor 1) if  _n  is  not
       specified.  If the file does not exist it is created.

       The general format for appending output is:

              [_n]>>>>_w_o_r_d


   RReeddiirreeccttiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr
       This  construct allows both the standard output (file descriptor 1) and
       the standard error output (file descriptor 2) to be redirected  to  the
       file whose name is the expansion of _w_o_r_d.

       There  are  two  formats  for  redirecting standard output and standard
       error:

              &&>>_w_o_r_d
       and
              >>&&_w_o_r_d

       Of the two forms, the first is preferred.  This is semantically equiva-
       lent to

              >>_w_o_r_d 2>>&&1

       When  using  the second form, _w_o_r_d may not expand to a number or --.  If
       it does,  other  redirection  operators  apply  (see  DDuupplliiccaattiinngg  FFiillee
       DDeessccrriippttoorrss below) for compatibility reasons.

   AAppppeennddiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr
       This  construct allows both the standard output (file descriptor 1) and
       the standard error output (file descriptor 2) to  be  appended  to  the
       file whose name is the expansion of _w_o_r_d.

       The format for appending standard output and standard error is:

              &&>>>>_w_o_r_d

       This is semantically equivalent to

              >>>>_w_o_r_d 2>>&&1

       (see DDuupplliiccaattiinngg FFiillee DDeessccrriippttoorrss below).

   HHeerree DDooccuummeennttss
       This  type  of  redirection  instructs the shell to read input from the
       current source until a line containing only _d_e_l_i_m_i_t_e_r (with no trailing
       blanks)  is seen.  All of the lines read up to that point are then used
       as the standard input for a command.

       The format of here-documents is:

              <<<<[--]_w_o_r_d
                      _h_e_r_e_-_d_o_c_u_m_e_n_t
              _d_e_l_i_m_i_t_e_r

       No parameter and variable expansion, command  substitution,  arithmetic
       expansion,  or pathname expansion is performed on _w_o_r_d.  If any charac-
       ters in _w_o_r_d are quoted, the _d_e_l_i_m_i_t_e_r is the result of  quote  removal
       on  _w_o_r_d, and the lines in the here-document are not expanded.  If _w_o_r_d
       is unquoted, all lines of the here-document are subjected to  parameter
       expansion,  command substitution, and arithmetic expansion, the charac-
       ter sequence \\<<nneewwlliinnee>> is ignored, and \\ must be  used  to  quote  the
       characters \\, $$, and ``.

       If the redirection operator is <<<<--, then all leading tab characters are
       stripped from input lines and  the  line  containing  _d_e_l_i_m_i_t_e_r.   This
       allows  here-documents within shell scripts to be indented in a natural
       fashion.

   HHeerree SSttrriinnggss
       A variant of here documents, the format is:

              <<<<<<_w_o_r_d

       The _w_o_r_d undergoes brace  expansion,  tilde  expansion,  parameter  and
       variable  expansion,  command  substitution,  arithmetic expansion, and
       quote removal.  Pathname expansion and  word  splitting  are  not  per-
       formed.   The  result  is supplied as a single string to the command on
       its standard input.

   DDuupplliiccaattiinngg FFiillee DDeessccrriippttoorrss
       The redirection operator

              [_n]<<&&_w_o_r_d

       is used to duplicate input file descriptors.  If _w_o_r_d expands to one or
       more  digits,  the file descriptor denoted by _n is made to be a copy of
       that file descriptor.  If the digits in _w_o_r_d  do  not  specify  a  file
       descriptor  open for input, a redirection error occurs.  If _w_o_r_d evalu-
       ates to --, file descriptor _n is closed.  If _n  is  not  specified,  the
       standard input (file descriptor 0) is used.

       The operator

              [_n]>>&&_w_o_r_d

       is  used  similarly  to duplicate output file descriptors.  If _n is not
       specified, the standard output (file descriptor 1)  is  used.   If  the
       digits  in _w_o_r_d do not specify a file descriptor open for output, a re-
       direction error occurs.  If _w_o_r_d evaluates to --, file descriptor  _n  is
       closed.   As  a special case, if _n is omitted, and _w_o_r_d does not expand
       to one or more digits or --, the standard output and standard error  are
       redirected as described previously.

   MMoovviinngg FFiillee DDeessccrriippttoorrss
       The redirection operator

              [_n]<<&&_d_i_g_i_t--

       moves  the  file descriptor _d_i_g_i_t to file descriptor _n, or the standard
       input (file descriptor 0) if _n is not specified.  _d_i_g_i_t is closed after
       being duplicated to _n.

       Similarly, the redirection operator

              [_n]>>&&_d_i_g_i_t--

       moves  the  file descriptor _d_i_g_i_t to file descriptor _n, or the standard
       output (file descriptor 1) if _n is not specified.

   OOppeenniinngg FFiillee DDeessccrriippttoorrss ffoorr RReeaaddiinngg aanndd WWrriittiinngg
       The redirection operator

              [_n]<<>>_w_o_r_d

       causes the file whose name is the expansion of _w_o_r_d to  be  opened  for
       both  reading and writing on file descriptor _n, or on file descriptor 0
       if _n is not specified.  If the file does not exist, it is created.

AALLIIAASSEESS
       _A_l_i_a_s_e_s allow a string to be substituted for a word when it is used  as
       the  first  word  of  a  simple command.  The shell maintains a list of
       aliases that may be set and unset with the aalliiaass  and  uunnaalliiaass  builtin
       commands  (see  SSHHEELLLL  BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  The first word of each
       simple command, if unquoted, is checked to see if it has an alias.   If
       so,  that word is replaced by the text of the alias.  The characters //,
       $$, ``, and == and any of the shell _m_e_t_a_c_h_a_r_a_c_t_e_r_s or  quoting  characters
       listed above may not appear in an alias name.  The replacement text may
       contain any valid shell input,  including  shell  metacharacters.   The
       first  word  of  the replacement text is tested for aliases, but a word
       that is identical to an alias being expanded is not expanded  a  second
       time.   This  means  that  one may alias llss to llss --FF, for instance, and
       bbaasshh does not try to recursively expand the replacement text.   If  the
       last  character  of  the  alias value is a _b_l_a_n_k, then the next command
       word following the alias is also checked for alias expansion.

       Aliases are created and listed with the aalliiaass command, and removed with
       the uunnaalliiaass command.

       There  is no mechanism for using arguments in the replacement text.  If
       arguments are needed, a shell function should be  used  (see  FFUUNNCCTTIIOONNSS
       below).

       Aliases  are not expanded when the shell is not interactive, unless the
       eexxppaanndd__aalliiaasseess shell option is set using sshhoopptt (see the description  of
       sshhoopptt under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).

       The  rules  concerning  the  definition and use of aliases are somewhat
       confusing.  BBaasshh always reads at  least  one  complete  line  of  input
       before  executing  any  of  the  commands  on  that  line.  Aliases are
       expanded when a command is read, not when it is  executed.   Therefore,
       an  alias definition appearing on the same line as another command does
       not take effect until the next line of input  is  read.   The  commands
       following the alias definition on that line are not affected by the new
       alias.  This behavior is also an issue  when  functions  are  executed.
       Aliases  are  expanded when a function definition is read, not when the
       function is executed, because a function definition is  itself  a  com-
       pound command.  As a consequence, aliases defined in a function are not
       available until after that function is executed.  To  be  safe,  always
       put  alias definitions on a separate line, and do not use aalliiaass in com-
       pound commands.

       For almost every purpose, aliases are superseded by shell functions.

FFUUNNCCTTIIOONNSS
       A shell function, defined  as  described  above  under  SSHHEELLLL  GGRRAAMMMMAARR,
       stores  a  series  of commands for later execution.  When the name of a
       shell function is used as a simple command name, the list  of  commands
       associated with that function name is executed.  Functions are executed
       in the context of the current shell;  no  new  process  is  created  to
       interpret  them  (contrast  this with the execution of a shell script).
       When a function is executed, the arguments to the function  become  the
       positional parameters during its execution.  The special parameter ## is
       updated to reflect the change.  Special parameter 00 is unchanged.   The
       first  element of the FFUUNNCCNNAAMMEE variable is set to the name of the func-
       tion while the function is executing.

       All other aspects of the  shell  execution  environment  are  identical
       between a function and its caller with these exceptions:  the DDEEBBUUGG and
       RREETTUURRNN traps (see the description  of  the  ttrraapp  builtin  under  SSHHEELLLL
       BBUUIILLTTIINN  CCOOMMMMAANNDDSS below) are not inherited unless the function has been
       given the ttrraaccee attribute (see the description of the  ddeeccllaarree  builtin
       below)  or  the --oo ffuunnccttrraaccee shell option has been enabled with the sseett
       builtin (in which case all  functions  inherit  the  DDEEBBUUGG  and  RREETTUURRNN
       traps),  and the EERRRR trap is not inherited unless the --oo eerrrrttrraaccee shell
       option has been enabled.

       Variables local to the function may be declared with the llooccaall  builtin
       command.  Ordinarily, variables and their values are shared between the
       function and its caller.

       The FFUUNNCCNNEESSTT variable, if set  to  a  numeric  value  greater  than  0,
       defines  a  maximum  function nesting level.  Function invocations that
       exceed the limit cause the entire command to abort.

       If the builtin command rreettuurrnn is executed in a function,  the  function
       completes  and  execution resumes with the next command after the func-
       tion call.  Any command associated with the  RREETTUURRNN  trap  is  executed
       before execution resumes.  When a function completes, the values of the
       positional parameters and the special parameter ## are restored  to  the
       values they had prior to the function's execution.

       Function  names and definitions may be listed with the --ff option to the
       ddeeccllaarree or ttyyppeesseett builtin commands.  The --FF option to ddeeccllaarree or ttyyppee--
       sseett  will  list the function names only (and optionally the source file
       and line number, if the eexxttddeebbuugg shell option is  enabled).   Functions
       may  be exported so that subshells automatically have them defined with
       the --ff option to the eexxppoorrtt builtin.   A  function  definition  may  be
       deleted  using  the  --ff  option  to the uunnsseett builtin.  Note that shell
       functions and variables with the same name may result in multiple iden-
       tically-named  entries  in  the environment passed to the shell's chil-
       dren.  Care should be taken in cases where this may cause a problem.

       Functions may be recursive.  The FFUUNNCCNNEESSTT variable may be used to limit
       the  depth  of the function call stack and restrict the number of func-
       tion invocations.  By default, no limit is imposed  on  the  number  of
       recursive calls.

AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN
       The  shell allows arithmetic expressions to be evaluated, under certain
       circumstances (see the lleett and ddeeccllaarree builtin commands and  AArriitthhmmeettiicc
       EExxppaannssiioonn).   Evaluation  is done in fixed-width integers with no check
       for overflow, though division by 0 is trapped and flagged as an  error.
       The  operators  and their precedence, associativity, and values are the
       same as in the C language.  The following list of operators is  grouped
       into  levels  of  equal-precedence operators.  The levels are listed in
       order of decreasing precedence.

       _i_d++++ _i_d----
              variable post-increment and post-decrement
       ++++_i_d ----_i_d
              variable pre-increment and pre-decrement
       -- ++    unary minus and plus
       !! ~~    logical and bitwise negation
       ****     exponentiation
       ** // %%  multiplication, division, remainder
       ++ --    addition, subtraction
       <<<< >>>>  left and right bitwise shifts
       <<== >>== << >>
              comparison
       ==== !!==  equality and inequality
       &&      bitwise AND
       ^^      bitwise exclusive OR
       ||      bitwise OR
       &&&&     logical AND
       ||||     logical OR
       _e_x_p_r??_e_x_p_r::_e_x_p_r
              conditional operator
       == **== //== %%== ++== --== <<<<== >>>>== &&== ^^== ||==
              assignment
       _e_x_p_r_1 ,, _e_x_p_r_2
              comma

       Shell variables are allowed as operands; parameter  expansion  is  per-
       formed before the expression is evaluated.  Within an expression, shell
       variables may also be referenced by name without  using  the  parameter
       expansion  syntax.  A shell variable that is null or unset evaluates to
       0 when referenced by name without using the parameter expansion syntax.
       The  value  of a variable is evaluated as an arithmetic expression when
       it is referenced, or when a variable which has been given  the  _i_n_t_e_g_e_r
       attribute using ddeeccllaarree --ii is assigned a value.  A null value evaluates
       to 0.  A shell variable need not have its _i_n_t_e_g_e_r attribute  turned  on
       to be used in an expression.

       Constants with a leading 0 are interpreted as octal numbers.  A leading
       0x or  0X  denotes  hexadecimal.   Otherwise,  numbers  take  the  form
       [_b_a_s_e_#]n,  where the optional _b_a_s_e is a decimal number between 2 and 64
       representing the arithmetic base, and _n is a number in that  base.   If
       _b_a_s_e_#  is omitted, then base 10 is used.  When specifying _n, the digits
       greater< than 9 are represented by the lowercase letters, the uppercase
       letters, @, and _, in that order.  If _b_a_s_e is less than or equal to 36,
       lowercase and uppercase letters may be used interchangeably  to  repre-
       sent numbers between 10 and 35.

       Operators  are  evaluated  in  order of precedence.  Sub-expressions in
       parentheses are evaluated first and may override the  precedence  rules
       above.

CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS
       Conditional  expressions  are  used  by the [[[[ compound command and the
       tteesstt and [[ builtin commands to test file attributes and perform  string
       and  arithmetic comparisons.  Expressions are formed from the following
       unary or binary primaries.  If any _f_i_l_e argument to  one  of  the  pri-
       maries is of the form _/_d_e_v_/_f_d_/_n, then file descriptor _n is checked.  If
       the _f_i_l_e argument to  one  of  the  primaries  is  one  of  _/_d_e_v_/_s_t_d_i_n,
       _/_d_e_v_/_s_t_d_o_u_t,  or _/_d_e_v_/_s_t_d_e_r_r, file descriptor 0, 1, or 2, respectively,
       is checked.

       Unless otherwise specified, primaries that operate on files follow sym-
       bolic links and operate on the target of the link, rather than the link
       itself.

       When used with [[[[, the << and >> operators sort  lexicographically  using
       the current locale.  The tteesstt command sorts using ASCII ordering.

       --aa _f_i_l_e
              True if _f_i_l_e exists.
       --bb _f_i_l_e
              True if _f_i_l_e exists and is a block special file.
       --cc _f_i_l_e
              True if _f_i_l_e exists and is a character special file.
       --dd _f_i_l_e
              True if _f_i_l_e exists and is a directory.
       --ee _f_i_l_e
              True if _f_i_l_e exists.
       --ff _f_i_l_e
              True if _f_i_l_e exists and is a regular file.
       --gg _f_i_l_e
              True if _f_i_l_e exists and is set-group-id.
       --hh _f_i_l_e
              True if _f_i_l_e exists and is a symbolic link.
       --kk _f_i_l_e
              True if _f_i_l_e exists and its ``sticky'' bit is set.
       --pp _f_i_l_e
              True if _f_i_l_e exists and is a named pipe (FIFO).
       --rr _f_i_l_e
              True if _f_i_l_e exists and is readable.
       --ss _f_i_l_e
              True if _f_i_l_e exists and has a size greater than zero.
       --tt _f_d  True if file descriptor _f_d is open and refers to a terminal.
       --uu _f_i_l_e
              True if _f_i_l_e exists and its set-user-id bit is set.
       --ww _f_i_l_e
              True if _f_i_l_e exists and is writable.
       --xx _f_i_l_e
              True if _f_i_l_e exists and is executable.
       --GG _f_i_l_e
              True if _f_i_l_e exists and is owned by the effective group id.
       --LL _f_i_l_e
              True if _f_i_l_e exists and is a symbolic link.
       --NN _f_i_l_e
              True  if  _f_i_l_e  exists  and  has been modified since it was last
              read.
       --OO _f_i_l_e
              True if _f_i_l_e exists and is owned by the effective user id.
       --SS _f_i_l_e
              True if _f_i_l_e exists and is a socket.
       _f_i_l_e_1 --eeff _f_i_l_e_2
              True if _f_i_l_e_1 and _f_i_l_e_2 refer to the same device and inode  num-
              bers.
       _f_i_l_e_1 -nntt _f_i_l_e_2
              True  if  _f_i_l_e_1  is  newer (according to modification date) than
              _f_i_l_e_2, or if _f_i_l_e_1 exists and _f_i_l_e_2 does not.
       _f_i_l_e_1 -oott _f_i_l_e_2
              True if _f_i_l_e_1 is older than _f_i_l_e_2, or if _f_i_l_e_2 exists and  _f_i_l_e_1
              does not.
       --oo _o_p_t_n_a_m_e
              True  if  the  shell option _o_p_t_n_a_m_e is enabled.  See the list of
              options under the description  of  the  --oo  option  to  the  sseett
              builtin below.
       --vv _v_a_r_n_a_m_e
              True  if  the shell variable _v_a_r_n_a_m_e is set (has been assigned a
              value).
       --RR _v_a_r_n_a_m_e
              True if the shell variable _v_a_r_n_a_m_e is set and is a  name  refer-
              ence.
       --zz _s_t_r_i_n_g
              True if the length of _s_t_r_i_n_g is zero.
       _s_t_r_i_n_g
       --nn _s_t_r_i_n_g
              True if the length of _s_t_r_i_n_g is non-zero.

       _s_t_r_i_n_g_1 ==== _s_t_r_i_n_g_2
       _s_t_r_i_n_g_1 == _s_t_r_i_n_g_2
              True  if  the strings are equal.  == should be used with the tteesstt
              command for POSIX conformance.  When used with the  [[[[  command,
              this performs pattern matching as described above (CCoommppoouunndd CCoomm--
              mmaannddss).

       _s_t_r_i_n_g_1 !!== _s_t_r_i_n_g_2
              True if the strings are not equal.

       _s_t_r_i_n_g_1 << _s_t_r_i_n_g_2
              True if _s_t_r_i_n_g_1 sorts before _s_t_r_i_n_g_2 lexicographically.

       _s_t_r_i_n_g_1 >> _s_t_r_i_n_g_2
              True if _s_t_r_i_n_g_1 sorts after _s_t_r_i_n_g_2 lexicographically.

       _a_r_g_1 OOPP _a_r_g_2
              OOPP is one of --eeqq, --nnee, --lltt, --llee, --ggtt, or --ggee.  These  arithmetic
              binary  operators return true if _a_r_g_1 is equal to, not equal to,
              less than, less than or equal to, greater than, or greater  than
              or  equal  to _a_r_g_2, respectively.  _A_r_g_1 and _a_r_g_2 may be positive
              or negative integers.

SSIIMMPPLLEE CCOOMMMMAANNDD EEXXPPAANNSSIIOONN
       When a simple command is executed, the  shell  performs  the  following
       expansions, assignments, and redirections, from left to right.

       1.     The  words  that  the  parser has marked as variable assignments
              (those preceding the command name) and  redirections  are  saved
              for later processing.

       2.     The  words that are not variable assignments or redirections are
              expanded.  If any words remain after expansion, the  first  word
              is  taken  to be the name of the command and the remaining words
              are the arguments.

       3.     Redirections are performed as described above under RREEDDIIRREECCTTIIOONN.

       4.     The text after the == in each variable assignment undergoes tilde
              expansion, parameter expansion, command substitution, arithmetic
              expansion,  and quote removal before being assigned to the vari-
              able.

       If no command name results, the variable assignments affect the current
       shell  environment.  Otherwise, the variables are added to the environ-
       ment of the executed command and do not affect the current shell  envi-
       ronment.   If  any  of  the assignments attempts to assign a value to a
       readonly variable, an error occurs, and the command exits with  a  non-
       zero status.

       If  no  command  name  results,  redirections are performed, but do not
       affect the current shell environment.  A redirection error  causes  the
       command to exit with a non-zero status.

       If  there is a command name left after expansion, execution proceeds as
       described below.  Otherwise, the command exits.  If one of  the  expan-
       sions  contained a command substitution, the exit status of the command
       is the exit status of the  last  command  substitution  performed.   If
       there were no command substitutions, the command exits with a status of
       zero.

CCOOMMMMAANNDD EEXXEECCUUTTIIOONN
       After a command has been split into words, if it results  in  a  simple
       command  and  an  optional list of arguments, the following actions are
       taken.

       If the command name contains no slashes, the shell attempts  to  locate
       it.   If  there  exists a shell function by that name, that function is
       invoked as described above in FFUUNNCCTTIIOONNSS.  If the name does not match  a
       function,  the shell searches for it in the list of shell builtins.  If
       a match is found, that builtin is invoked.

       If the name is neither a shell function nor a builtin, and contains  no
       slashes,  bbaasshh  searches  each element of the PPAATTHH for a directory con-
       taining an executable file by that name.  BBaasshh uses  a  hash  table  to
       remember  the  full pathnames of executable files (see hhaasshh under SSHHEELLLL
       BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  A full search of the directories in  PPAATTHH  is
       performed  only  if the command is not found in the hash table.  If the
       search is unsuccessful, the shell searches for a defined shell function
       named ccoommmmaanndd__nnoott__ffoouunndd__hhaannddllee.  If that function exists, it is invoked
       with the original command and the original command's arguments  as  its
       arguments,  and  the  function's exit status becomes the exit status of
       the shell.  If that function is not defined, the shell prints an  error
       message and returns an exit status of 127.

       If  the  search  is  successful, or if the command name contains one or
       more slashes, the shell executes the named program in a separate execu-
       tion environment.  Argument 0 is set to the name given, and the remain-
       ing arguments to the command are set to the arguments given, if any.

       If this execution fails because the file is not in  executable  format,
       and  the file is not a directory, it is assumed to be a _s_h_e_l_l _s_c_r_i_p_t, a
       file containing shell commands.  A subshell is spawned to  execute  it.
       This  subshell  reinitializes itself, so that the effect is as if a new
       shell had been invoked to handle the script, with  the  exception  that
       the  locations  of  commands  remembered  by the parent (see hhaasshh below
       under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS) are retained by the child.

       If the program is a file beginning with ##!!, the remainder of the  first
       line  specifies an interpreter for the program.  The shell executes the
       specified interpreter on operating systems that do not handle this exe-
       cutable format themselves.  The arguments to the interpreter consist of
       a single optional argument following the interpreter name on the  first
       line  of  the program, followed by the name of the program, followed by
       the command arguments, if any.

CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT
       The shell has an _e_x_e_c_u_t_i_o_n _e_n_v_i_r_o_n_m_e_n_t, which consists of  the  follow-
       ing:

       +o      open  files inherited by the shell at invocation, as modified by
              redirections supplied to the eexxeecc builtin

       +o      the current working directory as set by ccdd, ppuusshhdd, or  ppooppdd,  or
              inherited by the shell at invocation

       +o      the  file  creation  mode mask as set by uummaasskk or inherited from
              the shell's parent

       +o      current traps set by ttrraapp

       +o      shell parameters that are set by variable assignment or with sseett
              or inherited from the shell's parent in the environment

       +o      shell  functions  defined during execution or inherited from the
              shell's parent in the environment

       +o      options enabled at invocation (either by default  or  with  com-
              mand-line arguments) or by sseett

       +o      options enabled by sshhoopptt

       +o      shell aliases defined with aalliiaass

       +o      various  process  IDs,  including  those of background jobs, the
              value of $$$$, and the value of PPPPIIDD

       When a simple command other than a builtin or shell function is  to  be
       executed,  it  is invoked in a separate execution environment that con-
       sists of the following.  Unless otherwise noted, the values are  inher-
       ited from the shell.


       +o      the  shell's  open  files,  plus any modifications and additions
              specified by redirections to the command

       +o      the current working directory

       +o      the file creation mode mask

       +o      shell variables and functions  marked  for  export,  along  with
              variables exported for the command, passed in the environment

       +o      traps caught by the shell are reset to the values inherited from
              the shell's parent, and traps ignored by the shell are ignored

       A command invoked  in  this  separate  environment  cannot  affect  the
       shell's execution environment.

       Command  substitution, commands grouped with parentheses, and asynchro-
       nous commands are invoked in a subshell environment that is a duplicate
       of  the  shell  environment,  except that traps caught by the shell are
       reset to the values that the shell inherited from its parent at invoca-
       tion.  Builtin commands that are invoked as part of a pipeline are also
       executed in a subshell environment.  Changes made to the subshell envi-
       ronment cannot affect the shell's execution environment.

       Subshells spawned to execute command substitutions inherit the value of
       the --ee option from the parent shell.  When  not  in  _p_o_s_i_x  mode,  bbaasshh
       clears the --ee option in such subshells.

       If  a  command  is  followed  by a && and job control is not active, the
       default standard input for the command is  the  empty  file  _/_d_e_v_/_n_u_l_l.
       Otherwise,  the  invoked  command  inherits the file descriptors of the
       calling shell as modified by redirections.

EENNVVIIRROONNMMEENNTT
       When a program is invoked it is given an array of  strings  called  the
       _e_n_v_i_r_o_n_m_e_n_t.   This  is  a  list  of  _n_a_m_e-_v_a_l_u_e  pairs,  of  the  form
       _n_a_m_e=_v_a_l_u_e.

       The shell provides several ways  to  manipulate  the  environment.   On
       invocation, the shell scans its own environment and creates a parameter
       for each name found, automatically marking it for _e_x_p_o_r_t to child  pro-
       cesses.   Executed  commands  inherit  the environment.  The eexxppoorrtt and
       ddeeccllaarree --xx commands allow parameters and functions to be added  to  and
       deleted from the environment.  If the value of a parameter in the envi-
       ronment is modified, the new value becomes  part  of  the  environment,
       replacing  the  old.  The environment inherited by any executed command
       consists of the shell's initial environment, whose values may be  modi-
       fied  in  the  shell, less any pairs removed by the uunnsseett command, plus
       any additions via the eexxppoorrtt and ddeeccllaarree --xx commands.

       The environment for any _s_i_m_p_l_e _c_o_m_m_a_n_d or  function  may  be  augmented
       temporarily  by  prefixing  it with parameter assignments, as described
       above in PPAARRAAMMEETTEERRSS.  These assignment statements affect only the envi-
       ronment seen by that command.

       If  the  --kk option is set (see the sseett builtin command below), then _a_l_l
       parameter assignments are placed in the environment for a command,  not
       just those that precede the command name.

       When  bbaasshh  invokes  an  external command, the variable __ is set to the
       full filename of the command and passed to that command in its environ-
       ment.

EEXXIITT SSTTAATTUUSS
       The  exit  status  of  an executed command is the value returned by the
       _w_a_i_t_p_i_d system call or equivalent function.  Exit statuses fall between
       0  and  255, though, as explained below, the shell may use values above
       125 specially.  Exit statuses from shell builtins and compound commands
       are  also limited to this range. Under certain circumstances, the shell
       will use special values to indicate specific failure modes.

       For the shell's purposes, a command which exits with a zero exit status
       has  succeeded.   An exit status of zero indicates success.  A non-zero
       exit status indicates failure.  When a command terminates  on  a  fatal
       signal _N, bbaasshh uses the value of 128+_N as the exit status.

       If  a  command  is  not  found, the child process created to execute it
       returns a status of 127.  If a command is found but is not  executable,
       the return status is 126.

       If a command fails because of an error during expansion or redirection,
       the exit status is greater than zero.

       Shell builtin commands return a status of 0 (_t_r_u_e) if  successful,  and
       non-zero  (_f_a_l_s_e)  if an error occurs while they execute.  All builtins
       return an exit status of 2 to indicate incorrect usage.

       BBaasshh itself returns the exit  status  of  the  last  command  executed,
       unless  a  syntax  error occurs, in which case it exits with a non-zero
       value.  See also the eexxiitt builtin command below.

SSIIGGNNAALLSS
       When bbaasshh is interactive, in the  absence  of  any  traps,  it  ignores
       SSIIGGTTEERRMM (so that kkiillll 00 does not kill an interactive shell), and SSIIGGIINNTT
       is caught and handled (so that the wwaaiitt builtin is interruptible).   In
       all  cases,  bbaasshh  ignores  SSIIGGQQUUIITT.  If job control is in effect, bbaasshh
       ignores SSIIGGTTTTIINN, SSIIGGTTTTOOUU, and SSIIGGTTSSTTPP.

       Non-builtin commands run by bbaasshh have signal handlers set to the values
       inherited  by  the  shell  from its parent.  When job control is not in
       effect, asynchronous commands ignore SSIIGGIINNTT and SSIIGGQQUUIITT in addition  to
       these  inherited handlers.  Commands run as a result of command substi-
       tution ignore the keyboard-generated job control signals SSIIGGTTTTIINN, SSIIGGTT--
       TTOOUU, and SSIIGGTTSSTTPP.

       The  shell  exits by default upon receipt of a SSIIGGHHUUPP.  Before exiting,
       an interactive shell  resends  the  SSIIGGHHUUPP  to  all  jobs,  running  or
       stopped.  Stopped jobs are sent SSIIGGCCOONNTT to ensure that they receive the
       SSIIGGHHUUPP.  To prevent the shell from sending the signal to  a  particular
       job,  it  should be removed from the jobs table with the ddiissoowwnn builtin
       (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) or  marked  to  not  receive  SSIIGGHHUUPP
       using ddiissoowwnn --hh.

       If  the  hhuuppoonneexxiitt  shell  option has been set with sshhoopptt, bbaasshh sends a
       SSIIGGHHUUPP to all jobs when an interactive login shell exits.

       If bbaasshh is waiting for a command to complete and receives a signal  for
       which a trap has been set, the trap will not be executed until the com-
       mand completes.  When bbaasshh is waiting for an asynchronous  command  via
       the  wwaaiitt  builtin, the reception of a signal for which a trap has been
       set will cause the wwaaiitt builtin to return immediately with an exit sta-
       tus greater than 128, immediately after which the trap is executed.

JJOOBB CCOONNTTRROOLL
       _J_o_b  _c_o_n_t_r_o_l  refers  to  the ability to selectively stop (_s_u_s_p_e_n_d) the
       execution of processes and continue (_r_e_s_u_m_e) their execution at a later
       point.   A  user  typically  employs  this  facility via an interactive
       interface supplied jointly by the operating  system  kernel's  terminal
       driver and bbaasshh.

       The  shell  associates  a  _j_o_b with each pipeline.  It keeps a table of
       currently executing jobs, which may be listed with  the  jjoobbss  command.
       When  bbaasshh starts a job asynchronously (in the _b_a_c_k_g_r_o_u_n_d), it prints a
       line that looks like:

              [1] 25647

       indicating that this job is job number 1 and that the process ID of the
       last process in the pipeline associated with this job is 25647.  All of
       the processes in a single pipeline are members of the same  job.   BBaasshh
       uses the _j_o_b abstraction as the basis for job control.

       To  facilitate the implementation of the user interface to job control,
       the operating system maintains the notion of a _c_u_r_r_e_n_t _t_e_r_m_i_n_a_l _p_r_o_c_e_s_s
       _g_r_o_u_p _I_D.  Members of this process group (processes whose process group
       ID is equal to the current terminal process group ID) receive keyboard-
       generated  signals  such  as SSIIGGIINNTT.  These processes are said to be in
       the _f_o_r_e_g_r_o_u_n_d.  _B_a_c_k_g_r_o_u_n_d processes are those whose process group  ID
       differs from the terminal's; such processes are immune to keyboard-gen-
       erated signals.  Only foreground processes are allowed to read from or,
       if  the  user  so  specifies  with  stty tostop, write to the terminal.
       Background processes which attempt to read from  (write  to  when  stty
       tostop  is  in effect) the terminal are sent a SSIIGGTTTTIINN ((SSIIGGTTTTOOUU)) signal
       by the kernel's terminal driver, which,  unless  caught,  suspends  the
       process.

       If  the operating system on which bbaasshh is running supports job control,
       bbaasshh contains facilities to use it.  Typing the _s_u_s_p_e_n_d character (typ-
       ically ^^ZZ, Control-Z) while a process is running causes that process to
       be stopped and returns control to bbaasshh.   Typing  the  _d_e_l_a_y_e_d  _s_u_s_p_e_n_d
       character  (typically  ^^YY,  Control-Y) causes the process to be stopped
       when it attempts to read input from the terminal,  and  control  to  be
       returned  to bbaasshh.  The user may then manipulate the state of this job,
       using the bbgg command to continue it in the background, the  ffgg  command
       to continue it in the foreground, or the kkiillll command to kill it.  A ^^ZZ
       takes effect immediately, and has the additional side effect of causing
       pending output and typeahead to be discarded.

       There are a number of ways to refer to a job in the shell.  The charac-
       ter %% introduces a job specification (_j_o_b_s_p_e_c).  Job number  _n  may  be
       referred to as %%nn.  A job may also be referred to using a prefix of the
       name used to start it, or using a substring that appears in its command
       line.   For  example,  %%ccee  refers  to  a  stopped ccee job.  If a prefix
       matches more than one job, bbaasshh reports an error.  Using %%??ccee,  on  the
       other  hand,  refers to any job containing the string ccee in its command
       line.  If the substring matches more than  one  job,  bbaasshh  reports  an
       error.   The  symbols %%%% and %%++ refer to the shell's notion of the _c_u_r_-
       _r_e_n_t _j_o_b, which is the last job stopped while it was in the  foreground
       or started in the background.  The _p_r_e_v_i_o_u_s _j_o_b may be referenced using
       %%--.  If there is only a single job, %%++ and %%-- can both be used to refer
       to  that  job.   In  output pertaining to jobs (e.g., the output of the
       jjoobbss command), the current job is always flagged with a ++, and the pre-
       vious  job  with  a --.  A single % (with no accompanying job specifica-
       tion) also refers to the current job.

       Simply naming a job can be used to bring it into the foreground: %%11  is
       a  synonym  for  ````ffgg %%11'''', bringing job 1 from the background into the
       foreground.  Similarly, ````%%11 &&''''  resumes  job  1  in  the  background,
       equivalent to ````bbgg %%11''''.

       The  shell  learns immediately whenever a job changes state.  Normally,
       bbaasshh waits until it is about to print a prompt before reporting changes
       in  a  job's status so as to not interrupt any other output.  If the --bb
       option to the sseett builtin command is enabled, bbaasshh reports such changes
       immediately.   Any  trap  on  SSIIGGCCHHLLDD  is  executed for each child that
       exits.

       If an attempt to exit bbaasshh is made while jobs are stopped (or,  if  the
       cchheecckkjjoobbss  shell  option has been enabled using the sshhoopptt builtin, run-
       ning), the shell prints a warning message, and, if the cchheecckkjjoobbss option
       is  enabled,  lists  the jobs and their statuses.  The jjoobbss command may
       then be used to inspect their status.  If a second attempt to  exit  is
       made  without  an intervening command, the shell does not print another
       warning, and any stopped jobs are terminated.

PPRROOMMPPTTIINNGG
       When executing interactively, bbaasshh displays the primary prompt PPSS11 when
       it  is  ready  to  read a command, and the secondary prompt PPSS22 when it
       needs more input to complete  a  command.   BBaasshh  allows  these  prompt
       strings  to  be  customized  by inserting a number of backslash-escaped
       special characters that are decoded as follows:
              \\aa     an ASCII bell character (07)
              \\dd     the date in "Weekday Month Date" format (e.g.,  "Tue  May
                     26")
              \\DD{{_f_o_r_m_a_t}}
                     the  _f_o_r_m_a_t  is  passed  to _s_t_r_f_t_i_m_e(3) and the result is
                     inserted into the prompt string; an empty _f_o_r_m_a_t  results
                     in a locale-specific time representation.  The braces are
                     required
              \\ee     an ASCII escape character (033)
              \\hh     the hostname up to the first `.'
              \\HH     the hostname
              \\jj     the number of jobs currently managed by the shell
              \\ll     the basename of the shell's terminal device name
              \\nn     newline
              \\rr     carriage return
              \\ss     the name of the shell, the basename of  $$00  (the  portion
                     following the final slash)
              \\tt     the current time in 24-hour HH:MM:SS format
              \\TT     the current time in 12-hour HH:MM:SS format
              \\@@     the current time in 12-hour am/pm format
              \\AA     the current time in 24-hour HH:MM format
              \\uu     the username of the current user
              \\vv     the version of bbaasshh (e.g., 2.00)
              \\VV     the release of bbaasshh, version + patch level (e.g., 2.00.0)
              \\ww     the current working  directory,  with  $$HHOOMMEE  abbreviated
                     with  a tilde (uses the value of the PPRROOMMPPTT__DDIIRRTTRRIIMM vari-
                     able)
              \\WW     the basename of the current working directory, with $$HHOOMMEE
                     abbreviated with a tilde
              \\!!     the history number of this command
              \\##     the command number of this command
              \\$$     if the effective UID is 0, a ##, otherwise a $$
              \\_n_n_n   the character corresponding to the octal number _n_n_n
              \\\\     a backslash
              \\[[     begin  a sequence of non-printing characters, which could
                     be used to embed a terminal  control  sequence  into  the
                     prompt
              \\]]     end a sequence of non-printing characters

       The  command  number  and the history number are usually different: the
       history number of a command is its position in the history list,  which
       may  include  commands  restored  from  the  history  file (see HHIISSTTOORRYY
       below), while the command number is the position  in  the  sequence  of
       commands  executed  during the current shell session.  After the string
       is decoded, it is expanded via parameter expansion,  command  substitu-
       tion,  arithmetic expansion, and quote removal, subject to the value of
       the pprroommppttvvaarrss shell option (see the description of the  sshhoopptt  command
       under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).

RREEAADDLLIINNEE
       This  is  the library that handles reading input when using an interac-
       tive shell, unless the ----nnooeeddiittiinngg option is given at shell invocation.
       Line editing is also used when using the --ee option to the rreeaadd builtin.
       By default, the line editing commands are similar to those of Emacs.  A
       vi-style line editing interface is also available.  Line editing can be
       enabled at any time using the --oo eemmaaccss or --oo  vvii  options  to  the  sseett
       builtin  (see  SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  To turn off line editing
       after the shell is running, use the ++oo eemmaaccss or ++oo vvii  options  to  the
       sseett builtin.

   RReeaaddlliinnee NNoottaattiioonn
       In this section, the Emacs-style notation is used to denote keystrokes.
       Control keys are denoted by C-_k_e_y, e.g., C-n  means  Control-N.   Simi-
       larly,  _m_e_t_a  keys are denoted by M-_k_e_y, so M-x means Meta-X.  (On key-
       boards without a _m_e_t_a key, M-_x means ESC _x, i.e., press the Escape  key
       then the _x key.  This makes ESC the _m_e_t_a _p_r_e_f_i_x.  The combination M-C-_x
       means ESC-Control-_x, or press the Escape key then hold the Control  key
       while pressing the _x key.)

       Readline commands may be given numeric _a_r_g_u_m_e_n_t_s, which normally act as
       a repeat count.  Sometimes, however, it is the  sign  of  the  argument
       that  is  significant.   Passing  a negative argument to a command that
       acts in the forward direction (e.g., kkiillll--lliinnee) causes that command  to
       act  in  a  backward direction.  Commands whose behavior with arguments
       deviates from this are noted below.

       When a command is described as _k_i_l_l_i_n_g text, the text deleted is  saved
       for possible future retrieval (_y_a_n_k_i_n_g).  The killed text is saved in a
       _k_i_l_l _r_i_n_g.  Consecutive kills cause the text to be accumulated into one
       unit, which can be yanked all at once.  Commands which do not kill text
       separate the chunks of text on the kill ring.

   RReeaaddlliinnee IInniittiiaalliizzaattiioonn
       Readline is customized by putting commands in  an  initialization  file
       (the  _i_n_p_u_t_r_c  file).  The name of this file is taken from the value of
       the IINNPPUUTTRRCC variable.  If  that  variable  is  unset,  the  default  is
       _~_/_._i_n_p_u_t_r_c.   When a program which uses the readline library starts up,
       the initialization file is read, and the key bindings and variables are
       set.   There  are  only  a few basic constructs allowed in the readline
       initialization file.  Blank lines are ignored.  Lines beginning with  a
       ##  are  comments.   Lines  beginning with a $$ indicate conditional con-
       structs.  Other lines denote key bindings and variable settings.

       The default key-bindings may be changed with an  _i_n_p_u_t_r_c  file.   Other
       programs that use this library may add their own commands and bindings.

       For example, placing

              M-Control-u: universal-argument
       or
              C-Meta-u: universal-argument
       into the _i_n_p_u_t_r_c would make M-C-u execute the readline command  _u_n_i_v_e_r_-
       _s_a_l_-_a_r_g_u_m_e_n_t.

       The  following  symbolic  character  names are recognized: _R_U_B_O_U_T, _D_E_L,
       _E_S_C, _L_F_D, _N_E_W_L_I_N_E, _R_E_T, _R_E_T_U_R_N, _S_P_C, _S_P_A_C_E, and _T_A_B.

       In addition to command names, readline allows keys to  be  bound  to  a
       string that is inserted when the key is pressed (a _m_a_c_r_o).

   RReeaaddlliinnee KKeeyy BBiinnddiinnggss
       The  syntax for controlling key bindings in the _i_n_p_u_t_r_c file is simple.
       All that is required is the name of the command or the text of a  macro
       and  a key sequence to which it should be bound. The name may be speci-
       fied in one of two ways: as a symbolic key name, possibly with _M_e_t_a_- or
       _C_o_n_t_r_o_l_- prefixes, or as a key sequence.

       When using the form kkeeyynnaammee:_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, _k_e_y_n_a_m_e is the name
       of a key spelled out in English.  For example:

              Control-u: universal-argument
              Meta-Rubout: backward-kill-word
              Control-o: "> output"

       In the above example, _C_-_u is bound to the function  uunniivveerrssaall--aarrgguummeenntt,
       _M_-_D_E_L  is bound to the function bbaacckkwwaarrdd--kkiillll--wwoorrdd, and _C_-_o is bound to
       run the macro expressed on the right hand side (that is, to insert  the
       text ``> output'' into the line).

       In  the  second  form,  ""kkeeyysseeqq"":_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, kkeeyysseeqq differs
       from kkeeyynnaammee above in that strings denoting an entire key sequence  may
       be  specified  by  placing the sequence within double quotes.  Some GNU
       Emacs style key escapes can be used, as in the following  example,  but
       the symbolic character names are not recognized.

              "\C-u": universal-argument
              "\C-x\C-r": re-read-init-file
              "\e[11~": "Function Key 1"

       In this example, _C_-_u is again bound to the function uunniivveerrssaall--aarrgguummeenntt.
       _C_-_x _C_-_r is bound to the function rree--rreeaadd--iinniitt--ffiillee, and _E_S_C _[ _1 _1 _~  is
       bound to insert the text ``Function Key 1''.

       The full set of GNU Emacs style escape sequences is
              \\CC--    control prefix
              \\MM--    meta prefix
              \\ee     an escape character
              \\\\     backslash
              \\""     literal "
              \\''     literal '

       In  addition  to  the GNU Emacs style escape sequences, a second set of
       backslash escapes is available:
              \\aa     alert (bell)
              \\bb     backspace
              \\dd     delete
              \\ff     form feed
              \\nn     newline
              \\rr     carriage return
              \\tt     horizontal tab
              \\vv     vertical tab
              \\_n_n_n   the eight-bit character whose value is  the  octal  value
                     _n_n_n (one to three digits)
              \\xx_H_H   the  eight-bit  character  whose value is the hexadecimal
                     value _H_H (one or two hex digits)

       When entering the text of a macro, single or double quotes must be used
       to indicate a macro definition.  Unquoted text is assumed to be a func-
       tion name.  In the macro body, the backslash  escapes  described  above
       are  expanded.   Backslash  will quote any other character in the macro
       text, including " and '.

       BBaasshh allows the current readline key bindings to be displayed or  modi-
       fied  with  the bbiinndd builtin command.  The editing mode may be switched
       during interactive use by using the --oo option to the sseett  builtin  com-
       mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).

   RReeaaddlliinnee VVaarriiaabblleess
       Readline has variables that can be used to further customize its behav-
       ior.  A variable may be set in the _i_n_p_u_t_r_c file with a statement of the
       form

              sseett _v_a_r_i_a_b_l_e_-_n_a_m_e _v_a_l_u_e

       Except  where  noted,  readline variables can take the values OOnn or OOffff
       (without regard to case).  Unrecognized  variable  names  are  ignored.
       When  a variable value is read, empty or null values, "on" (case-insen-
       sitive), and "1" are equivalent to OOnn.  All other values are equivalent
       to OOffff.  The variables and their default values are:

       bbeellll--ssttyyllee ((aauuddiibbllee))
              Controls  what  happens when readline wants to ring the terminal
              bell.  If set to nnoonnee, readline never rings the bell.  If set to
              vviissiibbllee,  readline  uses a visible bell if one is available.  If
              set to aauuddiibbllee, readline attempts to ring the terminal's bell.
       bbiinndd--ttttyy--ssppeecciiaall--cchhaarrss ((OOnn))
              If set to OOnn, readline attempts to bind the  control  characters
              treated specially by the kernel's terminal driver to their read-
              line equivalents.
       ccoolloorreedd--ssttaattss ((OOffff))
              If set to OOnn, readline displays possible completions using  dif-
              ferent  colors  to  indicate their file type.  The color defini-
              tions are taken from the  value  of  the  LLSS__CCOOLLOORRSS  environment
              variable.
       ccoommmmeenntt--bbeeggiinn ((````##''''))
              The  string  that  is  inserted when the readline iinnsseerrtt--ccoommmmeenntt
              command is executed.  This command is bound to MM--## in emacs mode
              and to ## in vi command mode.
       ccoommpplleettiioonn--iiggnnoorree--ccaassee ((OOffff))
              If set to OOnn, readline performs filename matching and completion
              in a case-insensitive fashion.
       ccoommpplleettiioonn--pprreeffiixx--ddiissppllaayy--lleennggtthh ((00))
              The length in characters of the common prefix of a list of  pos-
              sible  completions that is displayed without modification.  When
              set to a value greater than zero, common  prefixes  longer  than
              this  value are replaced with an ellipsis when displaying possi-
              ble completions.
       ccoommpplleettiioonn--qquueerryy--iitteemmss ((110000))
              This determines when the user is queried about viewing the  num-
              ber  of  possible  completions generated by the ppoossssiibbllee--ccoommppllee--
              ttiioonnss command.  It may be set to any integer value greater  than
              or  equal  to  zero.   If  the number of possible completions is
              greater than or equal to the value of this variable, the user is
              asked  whether or not he wishes to view them; otherwise they are
              simply listed on the terminal.
       ccoonnvveerrtt--mmeettaa ((OOnn))
              If set to OOnn, readline will convert characters with  the  eighth
              bit set to an ASCII key sequence by stripping the eighth bit and
              prefixing an escape character (in effect, using  escape  as  the
              _m_e_t_a _p_r_e_f_i_x).
       ddiissaabbllee--ccoommpplleettiioonn ((OOffff))
              If set to OOnn, readline will inhibit word completion.  Completion
              characters will be inserted into the line as if  they  had  been
              mapped to sseellff--iinnsseerrtt.
       eeddiittiinngg--mmooddee ((eemmaaccss))
              Controls whether readline begins with a set of key bindings sim-
              ilar to _E_m_a_c_s or _v_i.  eeddiittiinngg--mmooddee can be set to either eemmaaccss or
              vvii.
       eecchhoo--ccoonnttrrooll--cchhaarraacctteerrss ((OOnn))
              When  set to OOnn, on operating systems that indicate they support
              it, readline echoes a character corresponding to a signal gener-
              ated from the keyboard.
       eennaabbllee--kkeeyyppaadd ((OOffff))
              When set to OOnn, readline will try to enable the application key-
              pad when it is called.  Some systems need  this  to  enable  the
              arrow keys.
       eennaabbllee--mmeettaa--kkeeyy ((OOnn))
              When  set  to  OOnn, readline will try to enable any meta modifier
              key the terminal claims to support when it is called.   On  many
              terminals, the meta key is used to send eight-bit characters.
       eexxppaanndd--ttiillddee ((OOffff))
              If  set  to  OOnn,  tilde  expansion  is  performed  when readline
              attempts word completion.
       hhiissttoorryy--pprreesseerrvvee--ppooiinntt ((OOffff))
              If set to OOnn, the history code attempts to place  point  at  the
              same  location on each history line retrieved with pprreevviioouuss--hhiiss--
              ttoorryy or nneexxtt--hhiissttoorryy.
       hhiissttoorryy--ssiizzee ((00))
              Set the maximum number of history entries saved in  the  history
              list.   If set to zero, any existing history entries are deleted
              and no new entries are saved.  If set to a value less than zero,
              the  number  of history entries is not limited.  By default, the
              number of history entries is not limited.
       hhoorriizzoonnttaall--ssccrroollll--mmooddee ((OOffff))
              When set to OOnn, makes readline use a single  line  for  display,
              scrolling the input horizontally on a single screen line when it
              becomes longer than the screen width rather than wrapping  to  a
              new line.
       iinnppuutt--mmeettaa ((OOffff))
              If  set to OOnn, readline will enable eight-bit input (that is, it
              will not strip the high  bit  from  the  characters  it  reads),
              regardless of what the terminal claims it can support.  The name
              mmeettaa--ffllaagg is a synonym for this variable.
       iisseeaarrcchh--tteerrmmiinnaattoorrss ((````CC--[[CC--JJ''''))
              The string of characters that should  terminate  an  incremental
              search  without  subsequently  executing the character as a com-
              mand.  If this variable has not been given a value, the  charac-
              ters _E_S_C and _C_-_J will terminate an incremental search.
       kkeeyymmaapp ((eemmaaccss))
              Set  the current readline keymap.  The set of valid keymap names
              is _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_-_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.  The default value is  _e_m_a_c_s;  the
              value of eeddiittiinngg--mmooddee also affects the default keymap.
       kkeeyysseeqq--ttiimmeeoouutt ((550000))
              Specifies  the  duration _r_e_a_d_l_i_n_e will wait for a character when
              reading an ambiguous key sequence (one that can form a  complete
              key sequence using the input read so far, or can take additional
              input to complete a  longer  key  sequence).   If  no  input  is
              received  within  the timeout, _r_e_a_d_l_i_n_e will use the shorter but
              complete key sequence.  The value is specified in  milliseconds,
              so  a value of 1000 means that _r_e_a_d_l_i_n_e will wait one second for
              additional input.  If this variable is set to a value less  than
              or  equal to zero, or to a non-numeric value, _r_e_a_d_l_i_n_e will wait
              until another key is pressed to decide  which  key  sequence  to
              complete.
       mmaarrkk--ddiirreeccttoorriieess ((OOnn))
              If set to OOnn, completed directory names have a slash appended.
       mmaarrkk--mmooddiiffiieedd--lliinneess ((OOffff))
              If  set  to  OOnn,  history lines that have been modified are dis-
              played with a preceding asterisk (**).
       mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess ((OOffff))
              If set to OOnn, completed names which are symbolic links to direc-
              tories   have   a  slash  appended  (subject  to  the  value  of
              mmaarrkk--ddiirreeccttoorriieess).
       mmaattcchh--hhiiddddeenn--ffiilleess ((OOnn))
              This variable, when set to OOnn, causes readline  to  match  files
              whose  names  begin  with  a  `.' (hidden files) when performing
              filename completion.  If set to OOffff, the  leading  `.'  must  be
              supplied by the user in the filename to be completed.
       mmeennuu--ccoommpplleettee--ddiissppllaayy--pprreeffiixx ((OOffff))
              If  set to OOnn, menu completion displays the common prefix of the
              list of possible completions (which may be empty) before cycling
              through the list.
       oouuttppuutt--mmeettaa ((OOffff))
              If  set  to OOnn, readline will display characters with the eighth
              bit set directly rather than as a meta-prefixed escape sequence.
       ppaaggee--ccoommpplleettiioonnss ((OOnn))
              If  set to OOnn, readline uses an internal _m_o_r_e-like pager to dis-
              play a screenful of possible completions at a time.
       pprriinntt--ccoommpplleettiioonnss--hhoorriizzoonnttaallllyy ((OOffff))
              If set to OOnn, readline will  display  completions  with  matches
              sorted  horizontally in alphabetical order, rather than down the
              screen.
       rreevveerrtt--aallll--aatt--nneewwlliinnee ((OOffff))
              If set to OOnn, readline will undo all changes  to  history  lines
              before returning when aacccceepptt--lliinnee is executed.  By default, his-
              tory lines may be modified  and  retain  individual  undo  lists
              across calls to rreeaaddlliinnee.
       sshhooww--aallll--iiff--aammbbiigguuoouuss ((OOffff))
              This  alters  the  default behavior of the completion functions.
              If set to OOnn, words which have more than one possible completion
              cause  the  matches  to be listed immediately instead of ringing
              the bell.
       sshhooww--aallll--iiff--uunnmmooddiiffiieedd ((OOffff))
              This alters the default behavior of the completion functions  in
              a fashion similar to sshhooww--aallll--iiff--aammbbiigguuoouuss.  If set to OOnn, words
              which have more than one possible completion without any  possi-
              ble  partial  completion (the possible completions don't share a
              common prefix)  cause  the  matches  to  be  listed  immediately
              instead of ringing the bell.
       sshhooww--mmooddee--iinn--pprroommpptt ((OOffff))
              If  set  to  OOnn,  add a character to the beginning of the prompt
              indicating the editing mode: emacs (@), vi  command  (:)  or  vi
              insertion (+).
       sskkiipp--ccoommpplleetteedd--tteexxtt ((OOffff))
              If  set  to OOnn, this alters the default completion behavior when
              inserting a single match into the line.  It's only  active  when
              performing  completion  in  the  middle  of a word.  If enabled,
              readline does not insert characters  from  the  completion  that
              match  characters  after  point  in the word being completed, so
              portions of the word following the cursor are not duplicated.
       vviissiibbllee--ssttaattss ((OOffff))
              If set to OOnn, a character denoting a file's type as reported  by
              _s_t_a_t(2)  is  appended to the filename when listing possible com-
              pletions.

   RReeaaddlliinnee CCoonnddiittiioonnaall CCoonnssttrruuccttss
       Readline implements a facility similar in  spirit  to  the  conditional
       compilation  features  of  the C preprocessor which allows key bindings
       and variable settings to be performed as the result  of  tests.   There
       are four parser directives used.

       $$iiff    The  $$iiff construct allows bindings to be made based on the edit-
              ing mode, the terminal being  used,  or  the  application  using
              readline.   The text of the test extends to the end of the line;
              no characters are required to isolate it.

              mmooddee   The mmooddee== form of the  $$iiff  directive  is  used  to  test
                     whether  readline  is  in  emacs or vi mode.  This may be
                     used in conjunction with  the  sseett  kkeeyymmaapp  command,  for
                     instance,  to  set  bindings  in  the  _e_m_a_c_s_-_s_t_a_n_d_a_r_d and
                     _e_m_a_c_s_-_c_t_l_x keymaps only if readline is  starting  out  in
                     emacs mode.

              tteerrmm   The  tteerrmm==  form may be used to include terminal-specific
                     key bindings, perhaps to bind the key sequences output by
                     the terminal's function keys.  The word on the right side
                     of the == is tested against the both full name of the ter-
                     minal  and  the  portion  of the terminal name before the
                     first --.  This allows _s_u_n to match both _s_u_n and  _s_u_n_-_c_m_d,
                     for instance.

              aapppplliiccaattiioonn
                     The aapppplliiccaattiioonn construct is used to include application-
                     specific  settings.   Each  program  using  the  readline
                     library  sets the _a_p_p_l_i_c_a_t_i_o_n _n_a_m_e, and an initialization
                     file can test for a particular value.  This could be used
                     to  bind key sequences to functions useful for a specific
                     program.  For instance, the following command adds a  key
                     sequence  that  quotes  the  current  or previous word in
                     bbaasshh:

                     $$iiff Bash
                     # Quote the current or previous word
                     "\C-xq": "\eb\"\ef\""
                     $$eennddiiff

       $$eennddiiff This command, as seen in the previous example, terminates an $$iiff
              command.

       $$eellssee  Commands in this branch of the $$iiff directive are executed if the
              test fails.

       $$iinncclluuddee
              This directive takes a single filename as an argument and  reads
              commands  and bindings from that file.  For example, the follow-
              ing directive would read _/_e_t_c_/_i_n_p_u_t_r_c:

              $$iinncclluuddee  _/_e_t_c_/_i_n_p_u_t_r_c

   SSeeaarrcchhiinngg
       Readline provides commands for searching through  the  command  history
       (see HHIISSTTOORRYY below) for lines containing a specified string.  There are
       two search modes: _i_n_c_r_e_m_e_n_t_a_l and _n_o_n_-_i_n_c_r_e_m_e_n_t_a_l.

       Incremental searches begin before the  user  has  finished  typing  the
       search  string.  As each character of the search string is typed, read-
       line displays the next entry from the history matching the string typed
       so  far.   An  incremental  search  requires only as many characters as
       needed to find the desired history entry.  The  characters  present  in
       the  value of the iisseeaarrcchh--tteerrmmiinnaattoorrss variable are used to terminate an
       incremental search.  If that variable has not been assigned a value the
       Escape  and  Control-J characters will terminate an incremental search.
       Control-G will abort an incremental search  and  restore  the  original
       line.   When the search is terminated, the history entry containing the
       search string becomes the current line.

       To find other matching entries in the history list, type  Control-S  or
       Control-R  as appropriate.  This will search backward or forward in the
       history for the next entry matching the search  string  typed  so  far.
       Any  other  key sequence bound to a readline command will terminate the
       search and execute that command.  For instance, a _n_e_w_l_i_n_e  will  termi-
       nate the search and accept the line, thereby executing the command from
       the history list.

       Readline remembers the last incremental search string.  If two Control-
       Rs  are  typed without any intervening characters defining a new search
       string, any remembered search string is used.

       Non-incremental searches read the entire search string before  starting
       to  search  for matching history lines.  The search string may be typed
       by the user or be part of the contents of the current line.

   RReeaaddlliinnee CCoommmmaanndd NNaammeess
       The following is a list of the names of the commands  and  the  default
       key sequences to which they are bound.  Command names without an accom-
       panying key sequence are unbound by default.  In the following descrip-
       tions,  _p_o_i_n_t refers to the current cursor position, and _m_a_r_k refers to
       a cursor position saved by the sseett--mmaarrkk command.  The text between  the
       point and mark is referred to as the _r_e_g_i_o_n.

   CCoommmmaannddss ffoorr MMoovviinngg
       bbeeggiinnnniinngg--ooff--lliinnee ((CC--aa))
              Move to the start of the current line.
       eenndd--ooff--lliinnee ((CC--ee))
              Move to the end of the line.
       ffoorrwwaarrdd--cchhaarr ((CC--ff))
              Move forward a character.
       bbaacckkwwaarrdd--cchhaarr ((CC--bb))
              Move back a character.
       ffoorrwwaarrdd--wwoorrdd ((MM--ff))
              Move forward to the end of the next word.  Words are composed of
              alphanumeric characters (letters and digits).
       bbaacckkwwaarrdd--wwoorrdd ((MM--bb))
              Move back to the start of the current or previous  word.   Words
              are composed of alphanumeric characters (letters and digits).
       sshheellll--ffoorrwwaarrdd--wwoorrdd
              Move  forward  to the end of the next word.  Words are delimited
              by non-quoted shell metacharacters.
       sshheellll--bbaacckkwwaarrdd--wwoorrdd
              Move back to the start of the current or previous  word.   Words
              are delimited by non-quoted shell metacharacters.
       cclleeaarr--ssccrreeeenn ((CC--ll))
              Clear  the  screen  leaving  the  current line at the top of the
              screen.  With an argument,  refresh  the  current  line  without
              clearing the screen.
       rreeddrraaww--ccuurrrreenntt--lliinnee
              Refresh the current line.

   CCoommmmaannddss ffoorr MMaanniippuullaattiinngg tthhee HHiissttoorryy
       aacccceepptt--lliinnee ((NNeewwlliinnee,, RReettuurrnn))
              Accept the line regardless of where the cursor is.  If this line
              is non-empty, add it to the history list according to the  state
              of  the HHIISSTTCCOONNTTRROOLL variable.  If the line is a modified history
              line, then restore the history line to its original state.
       pprreevviioouuss--hhiissttoorryy ((CC--pp))
              Fetch the previous command from the history list, moving back in
              the list.
       nneexxtt--hhiissttoorryy ((CC--nn))
              Fetch  the next command from the history list, moving forward in
              the list.
       bbeeggiinnnniinngg--ooff--hhiissttoorryy ((MM--<<))
              Move to the first line in the history.
       eenndd--ooff--hhiissttoorryy ((MM-->>))
              Move to the end of the input history, i.e., the  line  currently
              being entered.
       rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((CC--rr))
              Search  backward  starting  at  the current line and moving `up'
              through the  history  as  necessary.   This  is  an  incremental
              search.
       ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((CC--ss))
              Search  forward  starting  at the current line and moving `down'
              through the  history  as  necessary.   This  is  an  incremental
              search.
       nnoonn--iinnccrreemmeennttaall--rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((MM--pp))
              Search backward through the history starting at the current line
              using a non-incremental search for  a  string  supplied  by  the
              user.
       nnoonn--iinnccrreemmeennttaall--ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((MM--nn))
              Search  forward  through  the  history  using  a non-incremental
              search for a string supplied by the user.
       hhiissttoorryy--sseeaarrcchh--ffoorrwwaarrdd
              Search forward through the history for the string of  characters
              between  the start of the current line and the point.  This is a
              non-incremental search.
       hhiissttoorryy--sseeaarrcchh--bbaacckkwwaarrdd
              Search backward through the history for the string of characters
              between  the start of the current line and the point.  This is a
              non-incremental search.
       yyaannkk--nntthh--aarrgg ((MM--CC--yy))
              Insert the first argument to the previous command  (usually  the
              second word on the previous line) at point.  With an argument _n,
              insert the _nth word from the previous command (the words in  the
              previous  command  begin  with  word  0).   A  negative argument
              inserts the _nth word from the end of the previous command.  Once
              the  argument _n is computed, the argument is extracted as if the
              "!_n" history expansion had been specified.
       yyaannkk--llaasstt--aarrgg ((MM--..,, MM--__))
              Insert the last argument to the previous command (the last  word
              of the previous history entry).  With a numeric argument, behave
              exactly like yyaannkk--nntthh--aarrgg.  Successive  calls  to  yyaannkk--llaasstt--aarrgg
              move  back through the history list, inserting the last word (or
              the word specified by the argument to the first  call)  of  each
              line in turn.  Any numeric argument supplied to these successive
              calls determines the direction to move through the  history.   A
              negative  argument  switches  the  direction through the history
              (back or forward).  The history expansion facilities are used to
              extract the last word, as if the "!$" history expansion had been
              specified.
       sshheellll--eexxppaanndd--lliinnee ((MM--CC--ee))
              Expand the line as the shell does.  This performs alias and his-
              tory expansion as well as all of the shell word expansions.  See
              HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history  expansion.
       hhiissttoorryy--eexxppaanndd--lliinnee ((MM--^^))
              Perform  history  expansion  on  the  current line.  See HHIISSTTOORRYY
              EEXXPPAANNSSIIOONN below for a description of history expansion.
       mmaaggiicc--ssppaaccee
              Perform history expansion on  the  current  line  and  insert  a
              space.  See HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history
              expansion.
       aalliiaass--eexxppaanndd--lliinnee
              Perform alias expansion on the current line.  See AALLIIAASSEESS  above
              for a description of alias expansion.
       hhiissttoorryy--aanndd--aalliiaass--eexxppaanndd--lliinnee
              Perform history and alias expansion on the current line.
       iinnsseerrtt--llaasstt--aarrgguummeenntt ((MM--..,, MM--__))
              A synonym for yyaannkk--llaasstt--aarrgg.
       ooppeerraattee--aanndd--ggeett--nneexxtt ((CC--oo))
              Accept  the  current  line for execution and fetch the next line
              relative to the current line from the history for editing.   Any
              argument is ignored.
       eeddiitt--aanndd--eexxeeccuuttee--ccoommmmaanndd ((CC--xxCC--ee))
              Invoke  an  editor  on the current command line, and execute the
              result as shell commands.   BBaasshh  attempts  to  invoke  $$VVIISSUUAALL,
              $$EEDDIITTOORR, and _e_m_a_c_s as the editor, in that order.

   CCoommmmaannddss ffoorr CChhaannggiinngg TTeexxtt
       _e_n_d_-_o_f_-_f_i_l_e ((uussuuaallllyy CC--dd))
              The  character  indicating  end-of-file  as set, for example, by
              ``stty''.  If this character is read when there are  no  charac-
              ters  on  the  line,  and point is at the beginning of the line,
              Readline interprets it as the end of input and returns EEOOFF.
       ddeelleettee--cchhaarr ((CC--dd))
              Delete the character at point.  If this function is bound to the
              same character as the tty EEOOFF character, as CC--dd commonly is, see
              above for the effects.
       bbaacckkwwaarrdd--ddeelleettee--cchhaarr ((RRuubboouutt))
              Delete the character behind the cursor.  When  given  a  numeric
              argument, save the deleted text on the kill ring.
       ffoorrwwaarrdd--bbaacckkwwaarrdd--ddeelleettee--cchhaarr
              Delete  the  character under the cursor, unless the cursor is at
              the end of the line, in which case the character behind the cur-
              sor is deleted.
       qquuootteedd--iinnsseerrtt ((CC--qq,, CC--vv))
              Add  the next character typed to the line verbatim.  This is how
              to insert characters like CC--qq, for example.
       ttaabb--iinnsseerrtt ((CC--vv TTAABB))
              Insert a tab character.
       sseellff--iinnsseerrtt ((aa,, bb,, AA,, 11,, !!,, ......))
              Insert the character typed.
       ttrraannssppoossee--cchhaarrss ((CC--tt))
              Drag the character before point forward over  the  character  at
              point,  moving point forward as well.  If point is at the end of
              the line, then this transposes the two characters before  point.
              Negative arguments have no effect.
       ttrraannssppoossee--wwoorrddss ((MM--tt))
              Drag  the  word  before  point past the word after point, moving
              point over that word as well.  If point is at  the  end  of  the
              line, this transposes the last two words on the line.
       uuppccaassee--wwoorrdd ((MM--uu))
              Uppercase  the  current  (or  following)  word.  With a negative
              argument, uppercase the previous word, but do not move point.
       ddoowwnnccaassee--wwoorrdd ((MM--ll))
              Lowercase the current (or  following)  word.   With  a  negative
              argument, lowercase the previous word, but do not move point.
       ccaappiittaalliizzee--wwoorrdd ((MM--cc))
              Capitalize  the  current  (or  following) word.  With a negative
              argument, capitalize the previous word, but do not move point.
       oovveerrwwrriittee--mmooddee
              Toggle overwrite mode.  With an explicit positive numeric  argu-
              ment, switches to overwrite mode.  With an explicit non-positive
              numeric argument, switches to insert mode.  This command affects
              only  eemmaaccss mode; vvii mode does overwrite differently.  Each call
              to _r_e_a_d_l_i_n_e_(_) starts in insert mode.  In overwrite mode, charac-
              ters  bound to sseellff--iinnsseerrtt replace the text at point rather than
              pushing the text  to  the  right.   Characters  bound  to  bbaacckk--
              wwaarrdd--ddeelleettee--cchhaarr  replace  the  character  before  point  with a
              space.  By default, this command is unbound.

   KKiilllliinngg aanndd YYaannkkiinngg
       kkiillll--lliinnee ((CC--kk))
              Kill the text from point to the end of the line.
       bbaacckkwwaarrdd--kkiillll--lliinnee ((CC--xx RRuubboouutt))
              Kill backward to the beginning of the line.
       uunniixx--lliinnee--ddiissccaarrdd ((CC--uu))
              Kill backward from point to the  beginning  of  the  line.   The
              killed text is saved on the kill-ring.
       kkiillll--wwhhoollee--lliinnee
              Kill  all  characters on the current line, no matter where point
              is.
       kkiillll--wwoorrdd ((MM--dd))
              Kill from point to the end of the current word,  or  if  between
              words,  to  the  end  of the next word.  Word boundaries are the
              same as those used by ffoorrwwaarrdd--wwoorrdd.
       bbaacckkwwaarrdd--kkiillll--wwoorrdd ((MM--RRuubboouutt))
              Kill the word behind point.  Word boundaries  are  the  same  as
              those used by bbaacckkwwaarrdd--wwoorrdd.
       sshheellll--kkiillll--wwoorrdd ((MM--dd))
              Kill  from  point  to the end of the current word, or if between
              words, to the end of the next word.   Word  boundaries  are  the
              same as those used by sshheellll--ffoorrwwaarrdd--wwoorrdd.
       sshheellll--bbaacckkwwaarrdd--kkiillll--wwoorrdd ((MM--RRuubboouutt))
              Kill  the  word  behind  point.  Word boundaries are the same as
              those used by sshheellll--bbaacckkwwaarrdd--wwoorrdd.
       uunniixx--wwoorrdd--rruubboouutt ((CC--ww))
              Kill the word behind point, using white space as a  word  bound-
              ary.  The killed text is saved on the kill-ring.
       uunniixx--ffiilleennaammee--rruubboouutt
              Kill  the  word  behind  point,  using white space and the slash
              character as the word boundaries.  The killed text is  saved  on
              the kill-ring.
       ddeelleettee--hhoorriizzoonnttaall--ssppaaccee ((MM--\\))
              Delete all spaces and tabs around point.
       kkiillll--rreeggiioonn
              Kill the text in the current region.
       ccooppyy--rreeggiioonn--aass--kkiillll
              Copy the text in the region to the kill buffer.
       ccooppyy--bbaacckkwwaarrdd--wwoorrdd
              Copy  the word before point to the kill buffer.  The word bound-
              aries are the same as bbaacckkwwaarrdd--wwoorrdd.
       ccooppyy--ffoorrwwaarrdd--wwoorrdd
              Copy the word following point to  the  kill  buffer.   The  word
              boundaries are the same as ffoorrwwaarrdd--wwoorrdd.
       yyaannkk ((CC--yy))
              Yank the top of the kill ring into the buffer at point.
       yyaannkk--ppoopp ((MM--yy))
              Rotate  the kill ring, and yank the new top.  Only works follow-
              ing yyaannkk or yyaannkk--ppoopp.

   NNuummeerriicc AArrgguummeennttss
       ddiiggiitt--aarrgguummeenntt ((MM--00,, MM--11,, ......,, MM----))
              Add this digit to the argument already accumulating, or start  a
              new argument.  M-- starts a negative argument.
       uunniivveerrssaall--aarrgguummeenntt
              This  is another way to specify an argument.  If this command is
              followed by one or more digits, optionally with a leading  minus
              sign,  those digits define the argument.  If the command is fol-
              lowed by digits, executing  uunniivveerrssaall--aarrgguummeenntt  again  ends  the
              numeric  argument, but is otherwise ignored.  As a special case,
              if this command is immediately followed by a character  that  is
              neither  a  digit or minus sign, the argument count for the next
              command is multiplied by four.  The argument count is  initially
              one,  so  executing this function the first time makes the argu-
              ment count four, a second time makes the argument count sixteen,
              and so on.

   CCoommpplleettiinngg
       ccoommpplleettee ((TTAABB))
              Attempt  to  perform  completion on the text before point.  BBaasshh
              attempts completion treating the text as a variable (if the text
              begins  with  $$), username (if the text begins with ~~), hostname
              (if the text begins with @@), or command (including  aliases  and
              functions) in turn.  If none of these produces a match, filename
              completion is attempted.
       ppoossssiibbllee--ccoommpplleettiioonnss ((MM--??))
              List the possible completions of the text before point.
       iinnsseerrtt--ccoommpplleettiioonnss ((MM--**))
              Insert all completions of the text before point that would  have
              been generated by ppoossssiibbllee--ccoommpplleettiioonnss.
       mmeennuu--ccoommpplleettee
              Similar  to ccoommpplleettee, but replaces the word to be completed with
              a single match from the list of possible completions.   Repeated
              execution  of  mmeennuu--ccoommpplleettee  steps through the list of possible
              completions, inserting each match in turn.  At the  end  of  the
              list of completions, the bell is rung (subject to the setting of
              bbeellll--ssttyyllee) and the original text is restored.  An argument of _n
              moves  _n  positions  forward  in the list of matches; a negative
              argument may be used to move backward through  the  list.   This
              command  is  intended  to  be  bound  to  TTAABB, but is unbound by
              default.
       mmeennuu--ccoommpplleettee--bbaacckkwwaarrdd
              Identical to mmeennuu--ccoommpplleettee, but moves backward through the  list
              of  possible  completions,  as if mmeennuu--ccoommpplleettee had been given a
              negative argument.  This command is unbound by default.
       ddeelleettee--cchhaarr--oorr--lliisstt
              Deletes the character under the cursor if not at  the  beginning
              or  end  of  the  line (like ddeelleettee--cchhaarr).  If at the end of the
              line, behaves identically to ppoossssiibbllee--ccoommpplleettiioonnss.  This command
              is unbound by default.
       ccoommpplleettee--ffiilleennaammee ((MM--//))
              Attempt filename completion on the text before point.
       ppoossssiibbllee--ffiilleennaammee--ccoommpplleettiioonnss ((CC--xx //))
              List the possible completions of the text before point, treating
              it as a filename.
       ccoommpplleettee--uusseerrnnaammee ((MM--~~))
              Attempt completion on the text before point, treating  it  as  a
              username.
       ppoossssiibbllee--uusseerrnnaammee--ccoommpplleettiioonnss ((CC--xx ~~))
              List the possible completions of the text before point, treating
              it as a username.
       ccoommpplleettee--vvaarriiaabbllee ((MM--$$))
              Attempt completion on the text before point, treating  it  as  a
              shell variable.
       ppoossssiibbllee--vvaarriiaabbllee--ccoommpplleettiioonnss ((CC--xx $$))
              List the possible completions of the text before point, treating
              it as a shell variable.
       ccoommpplleettee--hhoossttnnaammee ((MM--@@))
              Attempt completion on the text before point, treating  it  as  a
              hostname.
       ppoossssiibbllee--hhoossttnnaammee--ccoommpplleettiioonnss ((CC--xx @@))
              List the possible completions of the text before point, treating
              it as a hostname.
       ccoommpplleettee--ccoommmmaanndd ((MM--!!))
              Attempt completion on the text before point, treating  it  as  a
              command  name.   Command  completion  attempts to match the text
              against  aliases,  reserved  words,   shell   functions,   shell
              builtins, and finally executable filenames, in that order.
       ppoossssiibbllee--ccoommmmaanndd--ccoommpplleettiioonnss ((CC--xx !!))
              List the possible completions of the text before point, treating
              it as a command name.
       ddyynnaammiicc--ccoommpplleettee--hhiissttoorryy ((MM--TTAABB))
              Attempt completion on the text before point, comparing the  text
              against  lines  from  the  history  list for possible completion
              matches.
       ddaabbbbrreevv--eexxppaanndd
              Attempt menu completion on the text before point, comparing  the
              text against lines from the history list for possible completion
              matches.
       ccoommpplleettee--iinnttoo--bbrraacceess ((MM--{{))
              Perform filename completion and insert the list of possible com-
              pletions  enclosed within braces so the list is available to the
              shell (see BBrraaccee EExxppaannssiioonn above).

   KKeeyybbooaarrdd MMaaccrrooss
       ssttaarrtt--kkbbdd--mmaaccrroo ((CC--xx (())
              Begin saving the characters  typed  into  the  current  keyboard
              macro.
       eenndd--kkbbdd--mmaaccrroo ((CC--xx ))))
              Stop saving the characters typed into the current keyboard macro
              and store the definition.
       ccaallll--llaasstt--kkbbdd--mmaaccrroo ((CC--xx ee))
              Re-execute the last keyboard macro defined, by making the  char-
              acters in the macro appear as if typed at the keyboard.
       pprriinntt--llaasstt--kkbbdd--mmaaccrroo (())
              Print  the  last keyboard macro defined in a format suitable for
              the _i_n_p_u_t_r_c file.

   MMiisscceellllaanneeoouuss
       rree--rreeaadd--iinniitt--ffiillee ((CC--xx CC--rr))
              Read in the contents of the _i_n_p_u_t_r_c file,  and  incorporate  any
              bindings or variable assignments found there.
       aabboorrtt ((CC--gg))
              Abort  the  current editing command and ring the terminal's bell
              (subject to the setting of bbeellll--ssttyyllee).
       ddoo--uuppppeerrccaassee--vveerrssiioonn ((MM--aa,, MM--bb,, MM--_x,, ......))
              If the metafied character _x is lowercase, run the  command  that
              is bound to the corresponding uppercase character.
       pprreeffiixx--mmeettaa ((EESSCC))
              Metafy the next character typed.  EESSCC ff is equivalent to MMeettaa--ff.
       uunnddoo ((CC--__,, CC--xx CC--uu))
              Incremental undo, separately remembered for each line.
       rreevveerrtt--lliinnee ((MM--rr))
              Undo all changes made to this line.  This is like executing  the
              uunnddoo  command  enough  times  to  return the line to its initial
              state.
       ttiillddee--eexxppaanndd ((MM--&&))
              Perform tilde expansion on the current word.
       sseett--mmaarrkk ((CC--@@,, MM--<<ssppaaccee>>))
              Set the mark to the point.  If a numeric argument  is  supplied,
              the mark is set to that position.
       eexxcchhaannggee--ppooiinntt--aanndd--mmaarrkk ((CC--xx CC--xx))
              Swap  the  point  with the mark.  The current cursor position is
              set to the saved position, and the old cursor position is  saved
              as the mark.
       cchhaarraacctteerr--sseeaarrcchh ((CC--]]))
              A character is read and point is moved to the next occurrence of
              that character.  A negative count searches for  previous  occur-
              rences.
       cchhaarraacctteerr--sseeaarrcchh--bbaacckkwwaarrdd ((MM--CC--]]))
              A  character  is  read and point is moved to the previous occur-
              rence of that character.  A negative count searches  for  subse-
              quent occurrences.
       sskkiipp--ccssii--sseeqquueennccee
              Read  enough  characters to consume a multi-key sequence such as
              those defined for keys like Home and End.  Such sequences  begin
              with a Control Sequence Indicator (CSI), usually ESC-[.  If this
              sequence is bound to "\[", keys producing  such  sequences  will
              have  no  effect  unless explicitly bound to a readline command,
              instead of inserting stray characters into the  editing  buffer.
              This is unbound by default, but usually bound to ESC-[.
       iinnsseerrtt--ccoommmmeenntt ((MM--##))
              Without  a  numeric  argument,  the  value  of the readline ccoomm--
              mmeenntt--bbeeggiinn variable is inserted at the beginning of the  current
              line.  If a numeric argument is supplied, this command acts as a
              toggle:  if the characters at the beginning of the line  do  not
              match  the value of ccoommmmeenntt--bbeeggiinn, the value is inserted, other-
              wise the characters in ccoommmmeenntt--bbeeggiinn are deleted from the begin-
              ning  of the line.  In either case, the line is accepted as if a
              newline had been typed.   The  default  value  of  ccoommmmeenntt--bbeeggiinn
              causes  this  command  to make the current line a shell comment.
              If a  numeric  argument  causes  the  comment  character  to  be
              removed, the line will be executed by the shell.
       gglloobb--ccoommpplleettee--wwoorrdd ((MM--gg))
              The  word  before  point  is  treated  as a pattern for pathname
              expansion, with an asterisk implicitly appended.   This  pattern
              is  used  to  generate a list of matching filenames for possible
              completions.
       gglloobb--eexxppaanndd--wwoorrdd ((CC--xx **))
              The word before point is  treated  as  a  pattern  for  pathname
              expansion,  and  the  list  of  matching  filenames is inserted,
              replacing the word.  If  a  numeric  argument  is  supplied,  an
              asterisk is appended before pathname expansion.
       gglloobb--lliisstt--eexxppaannssiioonnss ((CC--xx gg))
              The  list  of  expansions  that  would  have  been  generated by
              gglloobb--eexxppaanndd--wwoorrdd is displayed, and the line is  redrawn.   If  a
              numeric  argument  is  supplied,  an asterisk is appended before
              pathname expansion.
       dduummpp--ffuunnccttiioonnss
              Print all of the functions and their key bindings to  the  read-
              line output stream.  If a numeric argument is supplied, the out-
              put is formatted in such a way that it can be made  part  of  an
              _i_n_p_u_t_r_c file.
       dduummpp--vvaarriiaabblleess
              Print all of the settable readline variables and their values to
              the readline output stream.  If a numeric argument is  supplied,
              the  output  is formatted in such a way that it can be made part
              of an _i_n_p_u_t_r_c file.
       dduummpp--mmaaccrrooss
              Print all of the readline key sequences bound to macros and  the
              strings  they  output.   If  a numeric argument is supplied, the
              output is formatted in such a way that it can be made part of an
              _i_n_p_u_t_r_c file.
       ddiissppllaayy--sshheellll--vveerrssiioonn ((CC--xx CC--vv))
              Display  version information about the current instance of bbaasshh.

   PPrrooggrraammmmaabbllee CCoommpplleettiioonn
       When word completion is attempted for an  argument  to  a  command  for
       which  a  completion  specification (a _c_o_m_p_s_p_e_c) has been defined using
       the ccoommpplleettee builtin (see  SSHHEELLLL  BBUUIILLTTIINN  CCOOMMMMAANNDDSS  below),  the  pro-
       grammable completion facilities are invoked.

       First,  the  command  name  is  identified.  If the command word is the
       empty string (completion attempted at the beginning of an empty  line),
       any  compspec  defined  with  the  --EE option to ccoommpplleettee is used.  If a
       compspec has been defined for that command, the  compspec  is  used  to
       generate the list of possible completions for the word.  If the command
       word is a full pathname, a compspec for the full pathname  is  searched
       for  first.   If no compspec is found for the full pathname, an attempt
       is made to find a compspec for the portion following the  final  slash.
       If  those  searches  do  not result in a compspec, any compspec defined
       with the --DD option to ccoommpplleettee is used as the default.

       Once a compspec has been found, it is used  to  generate  the  list  of
       matching  words.   If a compspec is not found, the default bbaasshh comple-
       tion as described above under CCoommpplleettiinngg is performed.

       First, the actions specified by the compspec are  used.   Only  matches
       which  are prefixed by the word being completed are returned.  When the
       --ff or --dd option is used for filename or directory name completion,  the
       shell variable FFIIGGNNOORREE is used to filter the matches.

       Any  completions  specified  by  a pathname expansion pattern to the --GG
       option are generated next.  The words generated by the pattern need not
       match  the  word being completed.  The GGLLOOBBIIGGNNOORREE shell variable is not
       used to filter the matches, but the FFIIGGNNOORREE variable is used.

       Next, the string specified as the argument to the --WW option is  consid-
       ered.   The  string is first split using the characters in the IIFFSS spe-
       cial variable as delimiters.  Shell quoting is honored.  Each  word  is
       then  expanded  using  brace  expansion, tilde expansion, parameter and
       variable expansion, command substitution, and arithmetic expansion,  as
       described above under EEXXPPAANNSSIIOONN.  The results are split using the rules
       described above under WWoorrdd SSpplliittttiinngg.  The results of the expansion are
       prefix-matched against the word being completed, and the matching words
       become the possible completions.

       After these matches have been generated, any shell function or  command
       specified  with  the --FF and --CC options is invoked.  When the command or
       function is invoked, the CCOOMMPP__LLIINNEE, CCOOMMPP__PPOOIINNTT, CCOOMMPP__KKEEYY, and CCOOMMPP__TTYYPPEE
       variables are assigned values as described above under SShheellll VVaarriiaabblleess.
       If a shell function is being invoked,  the  CCOOMMPP__WWOORRDDSS  and  CCOOMMPP__CCWWOORRDD
       variables  are  also set.  When the function or command is invoked, the
       first argument ($$11) is the name of  the  command  whose  arguments  are
       being  completed, the second argument ($$22) is the word being completed,
       and the third argument ($$33) is the word preceding the word  being  com-
       pleted on the current command line.  No filtering of the generated com-
       pletions against the word being completed is performed; the function or
       command has complete freedom in generating the matches.

       Any  function specified with --FF is invoked first.  The function may use
       any of the shell facilities, including the  ccoommppggeenn  builtin  described
       below,  to  generate the matches.  It must put the possible completions
       in the CCOOMMPPRREEPPLLYY array variable, one per array element.

       Next, any command specified with the --CC option is invoked in  an  envi-
       ronment  equivalent to command substitution.  It should print a list of
       completions, one per line, to the standard output.   Backslash  may  be
       used to escape a newline, if necessary.

       After  all of the possible completions are generated, any filter speci-
       fied with the --XX option is applied to the list.  The filter is  a  pat-
       tern  as  used  for  pathname expansion; a && in the pattern is replaced
       with the text of the word being completed.  A literal && may be  escaped
       with  a  backslash; the backslash is removed before attempting a match.
       Any completion that matches the pattern will be removed from the  list.
       A leading !! negates the pattern; in this case any completion not match-
       ing the pattern will be removed.

       Finally, any prefix and suffix specified with the --PP and --SS options are
       added to each member of the completion list, and the result is returned
       to the readline completion code as the list of possible completions.

       If the previously-applied actions do not generate any matches, and  the
       --oo  ddiirrnnaammeess  option  was  supplied  to  ccoommpplleettee when the compspec was
       defined, directory name completion is attempted.

       If the --oo pplluussddiirrss option was supplied to ccoommpplleettee  when  the  compspec
       was defined, directory name completion is attempted and any matches are
       added to the results of the other actions.

       By default, if a compspec is found, whatever it generates  is  returned
       to  the  completion  code as the full set of possible completions.  The
       default bbaasshh completions are not attempted, and the readline default of
       filename completion is disabled.  If the --oo bbaasshhddeeffaauulltt option was sup-
       plied to ccoommpplleettee when the compspec was defined, the bbaasshh default  com-
       pletions are attempted if the compspec generates no matches.  If the --oo
       ddeeffaauulltt option was supplied to ccoommpplleettee when the compspec was  defined,
       readline's  default  completion will be performed if the compspec (and,
       if attempted, the default bbaasshh completions) generate no matches.

       When a compspec indicates that directory name  completion  is  desired,
       the  programmable completion functions force readline to append a slash
       to completed names which are symbolic links to directories, subject  to
       the  value of the mmaarrkk--ddiirreeccttoorriieess readline variable, regardless of the
       setting of the mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess readline variable.

       There is some support for dynamically modifying completions.   This  is
       most  useful  when used in combination with a default completion speci-
       fied with ccoommpplleettee --DD.  It's possible for shell functions  executed  as
       completion  handlers  to  indicate that completion should be retried by
       returning an exit status of 124.  If a shell function returns 124,  and
       changes the compspec associated with the command on which completion is
       being attempted (supplied as the first argument when  the  function  is
       executed), programmable completion restarts from the beginning, with an
       attempt to find a new compspec for that command.  This allows a set  of
       completions  to be built dynamically as completion is attempted, rather
       than being loaded all at once.

       For instance, assuming that there is a library of compspecs, each  kept
       in  a  file  corresponding  to  the  name of the command, the following
       default completion function would load completions dynamically:

       _completion_loader()
       {
            . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124
       }
       complete -D -F _completion_loader -o bashdefault -o default


HHIISSTTOORRYY
       When the --oo hhiissttoorryy option to the sseett builtin  is  enabled,  the  shell
       provides access to the _c_o_m_m_a_n_d _h_i_s_t_o_r_y, the list of commands previously
       typed.  The value of the HHIISSTTSSIIZZEE variable is used  as  the  number  of
       commands to save in a history list.  The text of the last HHIISSTTSSIIZZEE com-
       mands (default 500) is saved.  The shell stores  each  command  in  the
       history  list  prior to parameter and variable expansion (see EEXXPPAANNSSIIOONN
       above) but after history expansion is performed, subject to the  values
       of the shell variables HHIISSTTIIGGNNOORREE and HHIISSTTCCOONNTTRROOLL.

       On startup, the history is initialized from the file named by the vari-
       able HHIISSTTFFIILLEE (default _~_/_._b_a_s_h___h_i_s_t_o_r_y).  The file named by  the  value
       of  HHIISSTTFFIILLEE  is  truncated,  if necessary, to contain no more than the
       number of lines specified by the value of HHIISSTTFFIILLEESSIIZZEE.   If  HHIISSTTFFIILLEE--
       SSIIZZEE  is unset, or set to null, a non-numeric value, or a numeric value
       less than zero, the history file is not truncated.   When  the  history
       file  is  read, lines beginning with the history comment character fol-
       lowed immediately by a digit are interpreted as timestamps for the pre-
       ceding history line.  These timestamps are optionally displayed depend-
       ing on the value of the HHIISSTTTTIIMMEEFFOORRMMAATT variable.   When  a  shell  with
       history  enabled  exits,  the  last $$HHIISSTTSSIIZZEE lines are copied from the
       history list to $$HHIISSTTFFIILLEE.  If the hhiissttaappppeenndd shell option  is  enabled
       (see  the description of sshhoopptt under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below), the
       lines are appended to the history file, otherwise the history  file  is
       overwritten.   If  HHIISSTTFFIILLEE  is  unset,  or  if  the  history  file  is
       unwritable, the history is not saved.  If the  HHIISSTTTTIIMMEEFFOORRMMAATT  variable
       is  set,  time  stamps are written to the history file, marked with the
       history comment character, so they may be preserved across  shell  ses-
       sions.   This  uses  the history comment character to distinguish time-
       stamps from other history lines.  After saving the history, the history
       file is truncated to contain no more than HHIISSTTFFIILLEESSIIZZEE lines.  If HHIISSTT--
       FFIILLEESSIIZZEE is unset, or set to null, a non-numeric value,  or  a  numeric
       value less than zero, the history file is not truncated.

       The  builtin  command ffcc (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) may be used
       to list or edit and re-execute a portion of the history list.  The hhiiss--
       ttoorryy  builtin  may  be  used  to display or modify the history list and
       manipulate the history file.  When using command-line  editing,  search
       commands  are available in each editing mode that provide access to the
       history list.

       The shell allows control over which commands are saved on  the  history
       list.  The HHIISSTTCCOONNTTRROOLL and HHIISSTTIIGGNNOORREE variables may be set to cause the
       shell to save only a subset of the commands entered.  The ccmmddhhiisstt shell
       option,  if enabled, causes the shell to attempt to save each line of a
       multi-line command in the same history entry, adding  semicolons  where
       necessary  to preserve syntactic correctness.  The lliitthhiisstt shell option
       causes the shell to save the command with embedded newlines instead  of
       semicolons.  See the description of the sshhoopptt builtin below under SSHHEELLLL
       BBUUIILLTTIINN  CCOOMMMMAANNDDSS  for  information  on  setting  and  unsetting  shell
       options.

HHIISSTTOORRYY EEXXPPAANNSSIIOONN
       The  shell  supports a history expansion feature that is similar to the
       history expansion in ccsshh..  This section describes what syntax  features
       are  available.   This  feature  is  enabled by default for interactive
       shells, and can be disabled using the ++HH option to the sseett builtin com-
       mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below).  Non-interactive shells do not
       perform history expansion by default.

       History expansions introduce words from the history list into the input
       stream,  making  it  easy to repeat commands, insert the arguments to a
       previous command into the current input line, or fix errors in previous
       commands quickly.

       History  expansion  is  performed  immediately after a complete line is
       read, before the shell breaks it into words.  It  takes  place  in  two
       parts.   The  first is to determine which line from the history list to
       use during substitution.  The second is to select portions of that line
       for inclusion into the current one.  The line selected from the history
       is the _e_v_e_n_t, and the portions of that line that  are  acted  upon  are
       _w_o_r_d_s.   Various  _m_o_d_i_f_i_e_r_s  are  available  to manipulate the selected
       words.  The line is broken into words in the same fashion as when read-
       ing  input, so that several _m_e_t_a_c_h_a_r_a_c_t_e_r-separated words surrounded by
       quotes are considered one word.  History expansions are  introduced  by
       the  appearance  of  the  history  expansion  character,  which is !! by
       default.  Only backslash (\\) and single quotes can  quote  the  history
       expansion character.

       Several  characters inhibit history expansion if found immediately fol-
       lowing the history expansion character, even if it is unquoted:  space,
       tab,  newline,  carriage return, and ==.  If the eexxttgglloobb shell option is
       enabled, (( will also inhibit expansion.

       Several shell options settable with the sshhoopptt builtin may  be  used  to
       tailor  the  behavior  of  history  expansion.  If the hhiissttvveerriiffyy shell
       option is enabled (see the description of the sshhoopptt builtin below), and
       rreeaaddlliinnee  is  being  used,  history  substitutions  are not immediately
       passed to the shell parser.  Instead, the  expanded  line  is  reloaded
       into the rreeaaddlliinnee editing buffer for further modification.  If rreeaaddlliinnee
       is being used, and the hhiissttrreeeeddiitt shell option  is  enabled,  a  failed
       history  substitution will be reloaded into the rreeaaddlliinnee editing buffer
       for correction.  The --pp option to the hhiissttoorryy builtin  command  may  be
       used  to  see what a history expansion will do before using it.  The --ss
       option to the hhiissttoorryy builtin may be used to add commands to the end of
       the  history  list  without  actually  executing them, so that they are
       available for subsequent recall.

       The shell allows control of the various characters used by the  history
       expansion mechanism (see the description of hhiissttcchhaarrss above under SShheellll
       VVaarriiaabblleess).  The shell uses the history comment character to mark  his-
       tory timestamps when writing the history file.

   EEvveenntt DDeessiiggnnaattoorrss
       An  event designator is a reference to a command line entry in the his-
       tory list.  Unless the reference is absolute, events  are  relative  to
       the current position in the history list.

       !!      Start  a  history substitution, except when followed by a bbllaannkk,
              newline, carriage return, = or ( (when the eexxttgglloobb shell  option
              is enabled using the sshhoopptt builtin).
       !!_n     Refer to command line _n.
       !!--_n    Refer to the current command minus _n.
       !!!!     Refer to the previous command.  This is a synonym for `!-1'.
       !!_s_t_r_i_n_g
              Refer  to the most recent command preceding the current position
              in the history list starting with _s_t_r_i_n_g.
       !!??_s_t_r_i_n_g[[??]]
              Refer to the most recent command preceding the current  position
              in  the  history  list containing _s_t_r_i_n_g.  The trailing ?? may be
              omitted if _s_t_r_i_n_g is followed immediately by a newline.
       ^^_s_t_r_i_n_g_1^^_s_t_r_i_n_g_2^^
              Quick substitution.   Repeat  the  previous  command,  replacing
              _s_t_r_i_n_g_1  with  _s_t_r_i_n_g_2.  Equivalent to ``!!:s/_s_t_r_i_n_g_1/_s_t_r_i_n_g_2/''
              (see MMooddiiffiieerrss below).
       !!##     The entire command line typed so far.

   WWoorrdd DDeessiiggnnaattoorrss
       Word designators are used to select desired words from the event.  A  ::
       separates  the event specification from the word designator.  It may be
       omitted if the word designator begins with a ^^, $$, **, --, or  %%.   Words
       are  numbered from the beginning of the line, with the first word being
       denoted by 0 (zero).  Words are inserted into the  current  line  sepa-
       rated by single spaces.

       00 ((zzeerroo))
              The zeroth word.  For the shell, this is the command word.
       _n      The _nth word.
       ^^      The first argument.  That is, word 1.
       $$      The  last  word.   This  is  usually the last argument, but will
              expand to the zeroth word if there is only one word in the line.
       %%      The word matched by the most recent `?_s_t_r_i_n_g?' search.
       _x--_y    A range of words; `-_y' abbreviates `0-_y'.
       **      All  of  the words but the zeroth.  This is a synonym for `_1_-_$'.
              It is not an error to use ** if there is just  one  word  in  the
              event; the empty string is returned in that case.
       xx**     Abbreviates _x_-_$.
       xx--     Abbreviates _x_-_$ like xx**, but omits the last word.

       If  a  word  designator is supplied without an event specification, the
       previous command is used as the event.

   MMooddiiffiieerrss
       After the optional word designator, there may appear a sequence of  one
       or more of the following modifiers, each preceded by a `:'.

       hh      Remove a trailing filename component, leaving only the head.
       tt      Remove all leading filename components, leaving the tail.
       rr      Remove a trailing suffix of the form _._x_x_x, leaving the basename.
       ee      Remove all but the trailing suffix.
       pp      Print the new command but do not execute it.
       qq      Quote the substituted words, escaping further substitutions.
       xx      Quote the substituted words as with qq, but break into  words  at
              bbllaannkkss and newlines.
       ss//_o_l_d//_n_e_w//
              Substitute  _n_e_w  for  the  first  occurrence of _o_l_d in the event
              line.  Any delimiter can be used  in  place  of  /.   The  final
              delimiter  is  optional if it is the last character of the event
              line.  The delimiter may be quoted in _o_l_d and _n_e_w with a  single
              backslash.   If & appears in _n_e_w, it is replaced by _o_l_d.  A sin-
              gle backslash will quote the &.  If _o_l_d is null, it  is  set  to
              the  last  _o_l_d substituted, or, if no previous history substitu-
              tions took place, the last _s_t_r_i_n_g in a !!??_s_t_r_i_n_g[[??]]  search.
       &&      Repeat the previous substitution.
       gg      Cause changes to be applied over the entire event line.  This is
              used  in  conjunction  with `::ss' (e.g., `::ggss//_o_l_d//_n_e_w//') or `::&&'.
              If used with `::ss', any delimiter can be used in place of /,  and
              the  final  delimiter is optional if it is the last character of
              the event line.  An aa may be used as a synonym for gg.
       GG      Apply the following `ss' modifier once to each word in the  event
              line.

SSHHEELLLL 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,
              filenames  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] [--llppssvvPPSSVVXX]
       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.
              --XX     List  all  key  sequences bound to shell commands and the
                     associated commands in a format that  can  be  reused  as
                     input.

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

       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 [--ee]] [-@]] [_d_i_r]
              Change  the  current  directory to _d_i_r.  if _d_i_r is not supplied,
              the value of the HHOOMMEE shell variable is the default.  Any  addi-
              tional arguments following _d_i_r are ignored.  The variable CCDDPPAATTHH
              defines the search path for the directory containing  _d_i_r:  each
              directory  name  in  CCDDPPAATTHH  is  searched  for _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  causes  ccdd to use the physical directory
              structure by resolving symbolic links while traversing  _d_i_r  and
              before processing instances of _._. in _d_i_r (see also the --PP option
              to the sseett builtin command); the --LL option forces symbolic links
              to  be followed by resolving the link after processing instances
              of _._. in _d_i_r.  If _._. appears in _d_i_r, it is processed by removing
              the  immediately previous pathname component from _d_i_r, back to a
              slash or the beginning of _d_i_r.  If the  --ee  option  is  supplied
              with  --PP,  and  the current working directory cannot be success-
              fully determined after a successful directory  change,  ccdd  will
              return  an unsuccessful status.  On systems that support it, the
              --@@ option presents the extended  attributes  associated  with  a
              file  as  a directory.  An argument of -- is converted to $$OOLLDDPPWWDD
              before the directory change is attempted.  If a non-empty direc-
              tory  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  successfully
              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 filename
              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.
                      nnooqquuoottee Tell readline not to quote the  completed  words
                              if  they are filenames (quoting filenames is the
                              default).
                      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.
              --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 the function is  executed,  the
                      first  argument  ($$11)  is  the name of the command whose
                      arguments are being completed, the second argument  ($$22)
                      is the word being completed, and the third argument ($$33)
                      is the word preceding the word being  completed  on  the
                      current  command  line.   When it finishes, the possible
                      completions are retrieved from the value of the  CCOOMMPPRREE--
                      PPLLYY array variable.
              --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.
              --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.
              --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.
              --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.

              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-executing 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
              completion 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 [--aaAAffFFggiillnnrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
       ttyyppeesseett [--aaAAffFFggiillnnrrttuuxx] [--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, other than --ff  and  --FF,
              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 definitions; 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 displayed  as  well.   The  --FF
              option implies --ff.  The --gg option forces variables to be created
              or modified at the global scope, even when ddeeccllaarree  is  executed
              in  a  shell  function.   It is ignored in all other cases.  The
              following options can be used to restrict  output  to  variables
              with the specified attribute or to give variables attributes:
              --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.
              --nn     Give  each  _n_a_m_e  the _n_a_m_e_r_e_f attribute, making it a name
                     reference to another variable.  That  other  variable  is
                     defined by the value of _n_a_m_e.  All references and assign-
                     ments to _n_a_m_e,  except  for  changing  the  --nn  attribute
                     itself,  are  performed  on  the  variable  referenced by
                     _n_a_m_e's value.  The --nn  attribute  cannot  be  applied  to
                     array variables.
              --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, ddeeccllaarree and ttyyppeesseett make each _n_a_m_e local, as with
              the llooccaall command, unless the --gg option is supplied.  If a vari-
              able  name  is  followed by =_v_a_l_u_e, the value of the variable is
              set to _v_a_l_u_e.  When using --aa or --AA and the  compound  assignment
              syntax  to  create array variables, additional attributes do not
              take effect until subsequent assignments.  The return value is 0
              unless  an  invalid option is encountered, an attempt is made to
              define a function using ``-f foo=bar'', an attempt  is  made  to
              assign  a  value  to  a readonly variable, an attempt is made to
              assign a value to an array variable without using  the  compound
              assignment  syntax (see AArrrraayyss above), one of the _n_a_m_e_s is not a
              valid shell variable name, an attempt is made to turn off  read-
              only  status for a readonly variable, an attempt is made to turn
              off array status for an array variable, or an attempt is made to
              display a non-existent function with --ff.

       ddiirrss [[--ccllppvv]] [[++_n]] [[--_n]]
              Without  options,  displays  the  list  of  currently remembered
              directories.  The default display  is  on  a  single  line  with
              directory  names  separated by spaces.  Directories are added to
              the list with  the  ppuusshhdd  command;  the  ppooppdd  command  removes
              entries from the list.
              --cc     Clears  the  directory  stack  by  deleting  all  of  the
                     entries.
              --ll     Produces a listing  using  full  pathnames;  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.
              ++_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.

              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, remove each _j_o_b_s_p_e_c from the  table  of  active
              jobs.   If _j_o_b_s_p_e_c is not 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 the  --hh  option
              is  given,  each  _j_o_b_s_p_e_c  is not removed from the table, 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 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 0 unless a write error occurs.  If --nn is
              specified, the trailing newline is suppressed.  If the --ee option
              is  given,  interpretation  of  the  following backslash-escaped
              characters is enabled.  The --EE option disables  the  interpreta-
              tion  of these escape characters, 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
              \\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)
              \\uu_H_H_H_H the Unicode (ISO/IEC 10646) character whose value is  the
                     hexadecimal value _H_H_H_H (one to four hex digits)
              \\UU_H_H_H_H_H_H_H_H
                     the  Unicode (ISO/IEC 10646) character whose value is the
                     hexadecimal value _H_H_H_H_H_H_H_H (one to eight 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  eexxeeccffaaiill shell option is enabled.  In that 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 names of all exported
              variables 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  sup-
              plied with a _n_a_m_e that is not a function.

       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]
              The  first  form  selects a range of commands from _f_i_r_s_t to _l_a_s_t
              from the history list and  displays  or  edits  and  re-executes
              them.   _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 current 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  other-
              wise.   If _f_i_r_s_t is not specified it is set to the previous com-
              mand 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, _v_i is used.  When  editing  is  com-
              plete, 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.  _C_o_m_m_a_n_d is intepreted  the  same  as
              _f_i_r_s_t  above.  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 command.

              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 _n_a_m_e 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]
              Each time hhaasshh is invoked, the full pathname of the command _n_a_m_e
              is  determined  by searching the directories in $$PPAATTHH and remem-
              bered.  Any previously-remembered pathname is discarded.  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 filename 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  argu-
              ments  are  supplied  with  --tt,  the  _n_a_m_e is printed before the
              hashed full pathname.  The --ll option causes output  to  be  dis-
              played in a format that may be reused as input.  If no arguments
              are given, or if only --ll is supplied, information  about  remem-
              bered  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 append them  to
                     the current history list.
              --ww     Write the current history list to the history file, over-
                     writing 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.
              --nn     Display  information  only  about  jobs that have changed
                     status since the user was last notified of their  status.
              --pp     List  only  the  process  ID  of  the job's process group
                     leader.
              --rr     Display only running jobs.
              --ss     Display only 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 and the line to be assigned to that
              element as additional arguments.  _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 --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 a character string which contains three  types  of
              objects:  plain  characters, which are simply copied to standard
              output, character escape  sequences,  which  are  converted  and
              copied  to  the standard output, and format specifications, each
              of which causes printing of the next  successive  _a_r_g_u_m_e_n_t.   In
              addition to the standard _p_r_i_n_t_f(1) format specifications, pprriinnttff
              interprets the following extensions:
              %%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).
              %%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.
              %%((_d_a_t_e_f_m_t))TT
                     causes  pprriinnttff  to  output the date-time string resulting
                     from using _d_a_t_e_f_m_t as a format  string  for  _s_t_r_f_t_i_m_e(3).
                     The corresponding _a_r_g_u_m_e_n_t is an integer representing the
                     number of seconds since the epoch.  Two special  argument
                     values  may  be used: -1 represents the current time, and
                     -2 represents the time the  shell  was  invoked.   If  no
                     argument  is  specified,  conversion behaves as if -1 had
                     been given.  This is an exception  to  the  usual  pprriinnttff
                     behavior.

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

              The _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 as if it had been supplied
                     as the argument to the ccdd builtin.

              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 using the same rules  the  shell  uses
              for expansion (described above under WWoorrdd SSpplliittttiinngg).  The back-
              slash character (\\) may be used to remove  any  special  meaning
              for the next character read and for line continuation.  Options,
              if supplied, have the following meanings:
              --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  (or a specified number of characters) is
                     not read within _t_i_m_e_o_u_t seconds.  _t_i_m_e_o_u_t may be a  deci-
                     mal  number with a fractional portion following the deci-
                     mal point.  This option is  only  effective  if  rreeaadd  is
                     reading  input  from  a  terminal, pipe, or other special
                     file; it has no effect when reading from  regular  files.
                     If rreeaadd times out, rreeaadd saves any partial input read into
                     the specified variable  _n_a_m_e.   If  _t_i_m_e_o_u_t  is  0,  rreeaadd
                     returns  immediately,  without  trying  to read any data.
                     The exit status is 0 if input is available on the  speci-
                     fied  file descriptor, non-zero otherwise.  The exit sta-
                     tus is greater than 128 if the timeout is exceeded.
              --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), a variable assignment error (such as assign-
              ing to a readonly variable) occurs, or an invalid file  descrip-
              tor is supplied as the argument to --uu.

       rreeaaddoonnllyy [--aaAAff] [--pp] [_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 both options are supplied, --AA takes precedence.   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 other options may be
              used  to  restrict the output to a subset of the set of readonly
              names.  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 stop executing and return the value speci-
              fied by _n to its caller.  If _n is omitted, the return status  is
              that  of  the  last  command  executed in the function body.  If
              rreettuurrnn is 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 _n is supplied, the return value is its  least
              significant  8 bits.  The return status is non-zero if rreettuurrnn is
              supplied a non-numeric argument, or is used outside  a  function
              and  not  during execution of a script by .. or ssoouurrccee.  Any com-
              mand associated with the RREETTUURRNN trap is executed  before  execu-
              tion resumes after the function or script.

       sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n_-_n_a_m_e] [_a_r_g ...]
       sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n_-_n_a_m_e] [_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 mode, only shell variables  are  listed.
              The  output  is  sorted  according  to the current locale.  When
              options are specified, they set or unset shell attributes.   Any
              arguments  remaining after option processing are treated as val-
              ues for the positional parameters and are assigned, in order, to
              $$11,  $$22,  ......   $$_n.   Options,  if specified, have the following
              meanings:
              --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 _l_i_s_t, or a _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d
                      (see SSHHEELLLL GGRRAAMMMMAARR above),  exits with a  non-zero  sta-
                      tus.   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
                      !!.  If a compound command other than a subshell  returns
                      a  non-zero status because a command failed while --ee was
                      being ignored, the shell does not exit.  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.

                      If  a  compound  command or shell function executes in a
                      context where --ee is being ignored, none of the  commands
                      executed  within  the  compound command or function body
                      will be affected by the --ee setting, even if  --ee  is  set
                      and  a  command returns a failure status.  If a compound
                      command or shell function sets --ee while executing  in  a
                      context  where --ee is ignored, that setting will not have
                      any effect until the compound  command  or  the  command
                      containing the function call completes.
              --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).  All  processes  run
                      in a separate process group.  When a background job com-
                      pletes, the shell prints a line containing its exit sta-
                      tus.
              --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).  See SSEEEE AALLSSOO
                              below for a reference to a document that details
                              how posix mode affects bash's behavior.
                      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 resolve 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 settings controlling optional shell behav-
              ior.  The settings can be either those listed below, or, if  the
              --oo option is used, those available with the --oo option to the sseett
              builtin command.  With no options, or with the --pp option, a list
              of  all  settable  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 following 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, sshhoopptt
              shows only those options which are set or  unset,  respectively.
              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 filename 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
                      command's ==~~ operator and locale-specific string compar-
                      ison when using the [[[[ conditional  command's  <<  and  >>
                      operators.   Bash  versions  prior to bash-4.1 use ASCII
                      collation and _s_t_r_c_m_p(3); bash-4.1 and later use the cur-
                      rent locale's collation sequence and _s_t_r_c_o_l_l(3).
              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
                      (see previous item).
              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
                      (see  description  of ccoommppaatt3311) and the effect of inter-
                      rupting a command list.  Bash  versions  4.0  and  later
                      interrupt  the  list as if the shell received the inter-
                      rupt; previous versions continue with the  next  command
                      in the list.
              ccoommppaatt4411
                      If  set, bbaasshh, when in _p_o_s_i_x mode, treats a single quote
                      in a double-quoted  parameter  expansion  as  a  special
                      character.   The  single quotes must match (an even num-
                      ber) and the characters between the  single  quotes  are
                      considered  quoted.   This is the behavior of posix mode
                      through version 4.1.  The default bash behavior  remains
                      as in previous versions.
              ccoommppaatt4422
                      If  set, bbaasshh does not process the replacement string in
                      the pattern  substitution  word  expansion  using  quote
                      removal.
              ccoommpplleettee__ffuullllqquuoottee
                      If  set,  bbaasshh  quotes all shell metacharacters in file-
                      names and directory names  when  performing  completion.
                      If not set, bbaasshh removes metacharacters such as the dol-
                      lar sign from the set of characters that will be  quoted
                      in  completed filenames when these metacharacters appear
                      in shell variable references in words to  be  completed.
                      This  means  that  dollar  signs  in variable names that
                      expand to directories will not be quoted;  however,  any
                      dollar  signs appearing in filenames will not be quoted,
                      either.  This is active only when bash  is  using  back-
                      slashes  to quote completed filenames.  This variable is
                      set by default, which is the default  bash  behavior  in
                      versions through 4.2.
              ddiirreexxppaanndd
                      If  set,  bbaasshh replaces directory names with the results
                      of word expansion when performing  filename  completion.
                      This  changes  the  contents  of  the  readline  editing
                      buffer.  If not set, bbaasshh attempts to preserve what  the
                      user typed.
              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 EERRRR 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.
              gglloobbaasscciiiirraannggeess
                      If set,  range  expressions  used  in  pattern  matching
                      bracket  expressions (see PPaatttteerrnn MMaattcchhiinngg above) behave
                      as if in the traditional C locale when  performing  com-
                      parisons.   That  is,  the  current  locale's  collating
                      sequence is not taken into account, so bb will  not  col-
                      late  between  AA  and  BB,  and upper-case and lower-case
                      ASCII characters will collate together.
              gglloobbssttaarr
                      If set, the pattern **** used in a pathname expansion con-
                      text  will  match all files and zero or more directories
                      and subdirectories.  If the pattern is followed by a  //,
                      only directories and subdirectories match.
              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.
              llaassttppiippee
                      If set, and job control is not active,  the  shell  runs
                      the last command of a pipeline not executed in the back-
                      ground in the current shell environment.
              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 (true) or 1 (false) depending on the evalu-
              ation of the conditional expression _e_x_p_r.  Each operator and op-
              erand  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.  Operator  prece-
              dence is used when there are five or more arguments.
              !! _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
                     The following conditions are applied in the order listed.
                     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.

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

       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 SSIIGG 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  a
              pipeline (which may consist of a single simple command), a list,
              or a compound command returns a non-zero exit status, subject to
              the  following  conditions.  The 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 except the command
              following  the final &&&& or ||||, any command in a pipeline but the
              last, or if the command's return value is being  inverted  using
              !!.   These  are  the  same conditions obeyed by the eerrrreexxiitt (--ee)
              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, which is not necessar-
              ily 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
              function 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 and, on some systems, to its children
              --xx     The maximum number of file locks
              --TT     The maximum number of threads

              If  _l_i_m_i_t  is given, and the --aa option is not used, _l_i_m_i_t is the
              new value of the specified resource.  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  sup-
              plied, 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] [-nn] [_n_a_m_e ...]
              For each _n_a_m_e, remove the corresponding  variable  or  function.
              If the --vv option is given, each _n_a_m_e refers to a shell variable,
              and that variable is removed.  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.  If the --nn  option
              is  supplied, and _n_a_m_e is a variable with the _n_a_m_e_r_e_f attribute,
              _n_a_m_e will be unset rather than the variable it  references.   --nn
              has  no  effect if the --ff option is supplied.  If no options are
              supplied, each _n_a_m_e refers to a variable; if there is  no  vari-
              able  by  that name, any function with that name is unset.  Each
              unset variable or  function  is  removed  from  the  environment
              passed  to subsequent commands.  If any of CCOOMMPP__WWOORRDDBBRREEAAKKSS, RRAANN--
              DDOOMM, SSEECCOONNDDSS, LLIINNEENNOO, HHIISSTTCCMMDD, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, or DDIIRRSSTTAACCKK are
              unset, they lose their special properties, even if they are sub-
              sequently reset.  The exit status is true unless a _n_a_m_e is read-
              only.

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

RREESSTTRRIICCTTEEDD SSHHEELLLL
       If bbaasshh is started with the name rrbbaasshh, or the --rr option is supplied at
       invocation, the shell becomes restricted.  A restricted shell  is  used
       to  set  up an environment more controlled than the standard shell.  It
       behaves identically to bbaasshh with the exception that the  following  are
       disallowed or not performed:

       +o      changing directories with ccdd

       +o      setting or unsetting the values of SSHHEELLLL, PPAATTHH, EENNVV, or BBAASSHH__EENNVV

       +o      specifying command names containing //

       +o      specifying a filename containing a // as an  argument  to  the  ..
              builtin command

       +o      specifying  a  filename containing a slash as an argument to the
              --pp option to the hhaasshh builtin command

       +o      importing function definitions from  the  shell  environment  at
              startup

       +o      parsing  the  value  of  SSHHEELLLLOOPPTTSS from the shell environment at
              startup

       +o      redirecting output using the >, >|, <>, >&, &>, and >> redirect-
              ion operators

       +o      using the eexxeecc builtin command to replace the shell with another
              command

       +o      adding or deleting builtin commands with the --ff and  --dd  options
              to the eennaabbllee builtin command

       +o      using  the  eennaabbllee  builtin  command  to  enable  disabled shell
              builtins

       +o      specifying the --pp option to the ccoommmmaanndd builtin command

       +o      turning off restricted mode with sseett ++rr or sseett ++oo rreessttrriicctteedd.

       These restrictions are enforced after any startup files are read.

       When a command that is found to be a shell script is executed (see CCOOMM--
       MMAANNDD  EEXXEECCUUTTIIOONN  above),  rrbbaasshh turns off any restrictions in the shell
       spawned to execute the script.

SSEEEE AALLSSOO
       _B_a_s_h _R_e_f_e_r_e_n_c_e _M_a_n_u_a_l, Brian Fox and Chet Ramey
       _T_h_e _G_n_u _R_e_a_d_l_i_n_e _L_i_b_r_a_r_y, Brian Fox and Chet Ramey
       _T_h_e _G_n_u _H_i_s_t_o_r_y _L_i_b_r_a_r_y, Brian Fox and Chet Ramey
       _P_o_r_t_a_b_l_e _O_p_e_r_a_t_i_n_g _S_y_s_t_e_m _I_n_t_e_r_f_a_c_e _(_P_O_S_I_X_) _P_a_r_t _2_:  _S_h_e_l_l  _a_n_d  _U_t_i_l_i_-
       _t_i_e_s, IEEE --
              http://pubs.opengroup.org/onlinepubs/9699919799/
       http://tiswww.case.edu/~chet/bash/POSIX -- a description of posix mode
       _s_h(1), _k_s_h(1), _c_s_h(1)
       _e_m_a_c_s(1), _v_i(1)
       _r_e_a_d_l_i_n_e(3)

FFIILLEESS
       _/_b_i_n_/_b_a_s_h
              The bbaasshh executable
       _/_e_t_c_/_p_r_o_f_i_l_e
              The systemwide initialization file, executed for login shells
       _~_/_._b_a_s_h___p_r_o_f_i_l_e
              The personal initialization file, executed for login shells
       _~_/_._b_a_s_h_r_c
              The individual per-interactive-shell startup file
       _~_/_._b_a_s_h___l_o_g_o_u_t
              The individual login shell cleanup file, executed when  a  login
              shell exits
       _~_/_._i_n_p_u_t_r_c
              Individual _r_e_a_d_l_i_n_e initialization file

AAUUTTHHOORRSS
       Brian Fox, Free Software Foundation
       bfox@gnu.org

       Chet Ramey, Case Western Reserve University
       chet.ramey@case.edu

BBUUGG RREEPPOORRTTSS
       If you find a bug in bbaasshh,, you should report it.  But first, you should
       make sure that it really is a bug, and that it appears  in  the  latest
       version   of  bbaasshh.   The  latest  version  is  always  available  from
       _f_t_p_:_/_/_f_t_p_._g_n_u_._o_r_g_/_p_u_b_/_g_n_u_/_b_a_s_h_/.

       Once you have determined that a bug actually exists,  use  the  _b_a_s_h_b_u_g
       command  to submit a bug report.  If you have a fix, you are encouraged
       to mail that as well!  Suggestions and `philosophical' bug reports  may
       be  mailed  to  _b_u_g_-_b_a_s_h_@_g_n_u_._o_r_g  or  posted  to  the  Usenet newsgroup
       ggnnuu..bbaasshh..bbuugg.

       ALL bug reports should include:

       The version number of bbaasshh
       The hardware and operating system
       The compiler used to compile
       A description of the bug behaviour
       A short script or `recipe' which exercises the bug

       _b_a_s_h_b_u_g inserts the first three items automatically into  the  template
       it provides for filing a bug report.

       Comments and bug reports concerning this manual page should be directed
       to _c_h_e_t_._r_a_m_e_y_@_c_a_s_e_._e_d_u.

BBUUGGSS
       It's too big and too slow.

       There are some subtle differences between bbaasshh and traditional versions
       of sshh, mostly because of the PPOOSSIIXX specification.

       Aliases are confusing in some uses.

       Shell builtin commands and functions are not stoppable/restartable.

       Compound commands and command sequences of the form `a ; b ; c' are not
       handled gracefully  when  process  suspension  is  attempted.   When  a
       process  is stopped, the shell immediately executes the next command in
       the sequence.  It suffices to place the sequence  of  commands  between
       parentheses  to  force  it  into  a subshell, which may be stopped as a
       unit.

       Array variables may not (yet) be exported.

       There may be only one active coprocess at a time.



GNU Bash 4.3                    2014 February 2                        BASH(1)
