commit bash-20040902 snapshot

[thirdparty/bash.git] / doc / bash.0

BASH(1)                                                                BASH(1)



N\bNA\bAM\bME\bE
       bash - GNU Bourne-Again SHell

S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
       b\bba\bas\bsh\bh [options] [file]

C\bCO\bOP\bPY\bYR\bRI\bIG\bGH\bHT\bT
       Bash is Copyright (C) 1989-2004 by the Free Software Foundation, Inc.

D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
       B\bBa\bas\bsh\bh  is  an  s\bsh\bh-compatible  command language interpreter that executes
       commands read from the standard input or from a file.  B\bBa\bas\bsh\bh also incor-
       porates useful features from the _\bK_\bo_\br_\bn and _\bC shells (k\bks\bsh\bh and c\bcs\bsh\bh).

       B\bBa\bas\bsh\bh  is  intended  to be a conformant implementation of the IEEE POSIX
       Shell and Tools specification (IEEE Working Group 1003.2).

O\bOP\bPT\bTI\bIO\bON\bNS\bS
       In addition to the single-character shell  options  documented  in  the
       description  of  the s\bse\bet\bt builtin command, b\bba\bas\bsh\bh interprets the following
       options when it is invoked:

       -\b-c\bc _\bs_\bt_\br_\bi_\bn_\bg If the -\b-c\bc option is present,  then  commands  are  read  from
                 _\bs_\bt_\br_\bi_\bn_\bg.   If  there  are arguments after the _\bs_\bt_\br_\bi_\bn_\bg, they are
                 assigned to the positional parameters, starting with $\b$0\b0.
       -\b-i\bi        If the -\b-i\bi option is present, the shell is _\bi_\bn_\bt_\be_\br_\ba_\bc_\bt_\bi_\bv_\be.
       -\b-l\bl        Make b\bba\bas\bsh\bh act as if it had been invoked as a login shell (see
                 I\bIN\bNV\bVO\bOC\bCA\bAT\bTI\bIO\bON\bN below).
       -\b-r\br        If  the  -\b-r\br  option  is present, the shell becomes _\br_\be_\bs_\bt_\br_\bi_\bc_\bt_\be_\bd
                 (see R\bRE\bES\bST\bTR\bRI\bIC\bCT\bTE\bED\bD S\bSH\bHE\bEL\bLL\bL below).
       -\b-s\bs        If the -\b-s\bs 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.
       -\b-D\bD        A  list of all double-quoted strings preceded by $\b$ is printed
                 on the standard ouput.  These are the strings that  are  sub-
                 ject to language translation when the current locale is not C\bC
                 or P\bPO\bOS\bSI\bIX\bX.  This implies the -\b-n\bn option; no  commands  will  be
                 executed.
       [\b[-\b-+\b+]\b]O\bO [\b[_\bs_\bh_\bo_\bp_\bt_\b__\bo_\bp_\bt_\bi_\bo_\bn]\b]
                 _\bs_\bh_\bo_\bp_\bt_\b__\bo_\bp_\bt_\bi_\bo_\bn  is  one  of  the  shell options accepted by the
                 s\bsh\bho\bop\bpt\bt  builtin  (see  S\bSH\bHE\bEL\bLL\bL  B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  below).    If
                 _\bs_\bh_\bo_\bp_\bt_\b__\bo_\bp_\bt_\bi_\bo_\bn is present, -\b-O\bO sets the value of that option; +\b+O\bO
                 unsets it.  If _\bs_\bh_\bo_\bp_\bt_\b__\bo_\bp_\bt_\bi_\bo_\bn is not supplied,  the  names  and
                 values  of the shell options accepted by s\bsh\bho\bop\bpt\bt are printed on
                 the standard output.  If the invocation  option  is  +\b+O\bO,  the
                 output  is displayed in a format that may be reused as input.
       -\b--\b-        A -\b--\b- signals the end of options and disables  further  option
                 processing.   Any arguments after the -\b--\b- are treated as file-
                 names and arguments.  An argument of -\b- is equivalent to -\b--\b-.

       B\bBa\bas\bsh\bh also  interprets  a  number  of  multi-character  options.   These
       options  must  appear  on  the command line before the single-character
       options to be recognized.

       -\b--\b-d\bde\beb\bbu\bug\bgg\bge\ber\br
              Arrange for the debugger profile to be executed before the shell
              starts.   Turns  on extended debugging mode (see the description
              of the e\bex\bxt\btd\bde\beb\bbu\bug\bg option to the s\bsh\bho\bop\bpt\bt  builtin  below)  and  shell
              function tracing (see the description of the -\b-o\bo f\bfu\bun\bnc\bct\btr\bra\bac\bce\be option
              to the s\bse\bet\bt builtin below).
       -\b--\b-d\bdu\bum\bmp\bp-\b-p\bpo\bo-\b-s\bst\btr\bri\bin\bng\bgs\bs
              Equivalent to -\b-D\bD, but the  output  is  in  the  GNU  _\bg_\be_\bt_\bt_\be_\bx_\bt  p\bpo\bo
              (portable object) file format.
       -\b--\b-d\bdu\bum\bmp\bp-\b-s\bst\btr\bri\bin\bng\bgs\bs
              Equivalent to -\b-D\bD.
       -\b--\b-h\bhe\bel\blp\bp Display  a  usage  message  on standard output and exit success-
              fully.
       -\b--\b-i\bin\bni\bit\bt-\b-f\bfi\bil\ble\be _\bf_\bi_\bl_\be
       -\b--\b-r\brc\bcf\bfi\bil\ble\be _\bf_\bi_\bl_\be
              Execute commands from _\bf_\bi_\bl_\be instead of the standard personal ini-
              tialization  file  _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc  if  the  shell is interactive (see
              I\bIN\bNV\bVO\bOC\bCA\bAT\bTI\bIO\bON\bN below).

       -\b--\b-l\blo\bog\bgi\bin\bn
              Equivalent to -\b-l\bl.

       -\b--\b-n\bno\boe\bed\bdi\bit\bti\bin\bng\bg
              Do not use the GNU r\bre\bea\bad\bdl\bli\bin\bne\be library to read command  lines  when
              the shell is interactive.

       -\b--\b-n\bno\bop\bpr\bro\bof\bfi\bil\ble\be
              Do  not read either the system-wide startup file _\b/_\be_\bt_\bc_\b/_\bp_\br_\bo_\bf_\bi_\bl_\be or
              any  of  the  personal  initialization  files   _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bp_\br_\bo_\bf_\bi_\bl_\be,
              _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bl_\bo_\bg_\bi_\bn,  or  _\b~_\b/_\b._\bp_\br_\bo_\bf_\bi_\bl_\be.   By  default,  b\bba\bas\bsh\bh reads these
              files when it is  invoked  as  a  login  shell  (see  I\bIN\bNV\bVO\bOC\bCA\bAT\bTI\bIO\bON\bN
              below).

       -\b--\b-n\bno\bor\brc\bc Do  not  read  and  execute  the  personal  initialization  file
              _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc if the shell is interactive.  This  option  is  on  by
              default if the shell is invoked as s\bsh\bh.

       -\b--\b-p\bpo\bos\bsi\bix\bx
              Change  the behavior of b\bba\bas\bsh\bh where the default operation differs
              from the POSIX 1003.2 standard  to  match  the  standard  (_\bp_\bo_\bs_\bi_\bx
              _\bm_\bo_\bd_\be).

       -\b--\b-r\bre\bes\bst\btr\bri\bic\bct\bte\bed\bd
              The shell becomes restricted (see R\bRE\bES\bST\bTR\bRI\bIC\bCT\bTE\bED\bD S\bSH\bHE\bEL\bLL\bL below).

       -\b--\b-v\bve\ber\brb\bbo\bos\bse\be
              Equivalent to  -\b-v\bv.

       -\b--\b-v\bve\ber\brs\bsi\bio\bon\bn
              Show  version information for this instance of b\bba\bas\bsh\bh on the stan-
              dard output and exit successfully.

A\bAR\bRG\bGU\bUM\bME\bEN\bNT\bTS\bS
       If arguments remain after option processing, and neither the -\b-c\bc nor the
       -\b-s\bs  option  has  been supplied, the first argument is assumed to be the
       name of a file containing shell commands.  If b\bba\bas\bsh\bh is invoked  in  this
       fashion,  $\b$0\b0 is set to the name of the file, and the positional parame-
       ters are set to the remaining arguments.  B\bBa\bas\bsh\bh reads and executes  com-
       mands  from this file, then exits.  B\bBa\bas\bsh\bh'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 P\bPA\bAT\bTH\bH for the script.

I\bIN\bNV\bVO\bOC\bCA\bAT\bTI\bIO\bON\bN
       A  _\bl_\bo_\bg_\bi_\bn _\bs_\bh_\be_\bl_\bl is one whose first character of argument zero is a -\b-, or
       one started with the -\b--\b-l\blo\bog\bgi\bin\bn option.

       An _\bi_\bn_\bt_\be_\br_\ba_\bc_\bt_\bi_\bv_\be shell is one started without  non-option  arguments  and
       without the -\b-c\bc option whose standard input and error are both connected
       to terminals (as determined by _\bi_\bs_\ba_\bt_\bt_\by(3)), or one started with  the  -\b-i\bi
       option.   P\bPS\bS1\b1 is set and $\b$-\b- includes i\bi if b\bba\bas\bsh\bh is interactive, allowing
       a shell script or a startup file to test this state.

       The following paragraphs describe how b\bba\bas\bsh\bh executes its startup  files.
       If  any  of  the files exist but cannot be read, b\bba\bas\bsh\bh reports an error.
       Tildes are expanded in  file  names  as  described  below  under  T\bTi\bil\bld\bde\be
       E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn in the E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN section.

       When  b\bba\bas\bsh\bh is invoked as an interactive login shell, or as a non-inter-
       active shell with the -\b--\b-l\blo\bog\bgi\bin\bn option, it first reads and executes  com-
       mands  from  the file _\b/_\be_\bt_\bc_\b/_\bp_\br_\bo_\bf_\bi_\bl_\be, if that file exists.  After reading
       that file, it looks for _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bp_\br_\bo_\bf_\bi_\bl_\be, _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bl_\bo_\bg_\bi_\bn, and _\b~_\b/_\b._\bp_\br_\bo_\bf_\bi_\bl_\be,
       in  that order, and reads and executes commands from the first one that
       exists and is readable.  The -\b--\b-n\bno\bop\bpr\bro\bof\bfi\bil\ble\be option may be  used  when  the
       shell is started to inhibit this behavior.

       When  a  login  shell  exits, b\bba\bas\bsh\bh reads and executes commands from the
       file _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bl_\bo_\bg_\bo_\bu_\bt, if it exists.

       When an interactive shell that is not a login shell  is  started,  b\bba\bas\bsh\bh
       reads  and executes commands from _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc, if that file exists.  This
       may be inhibited by using the -\b--\b-n\bno\bor\brc\bc option.  The -\b--\b-r\brc\bcf\bfi\bil\ble\be _\bf_\bi_\bl_\be  option
       will  force  b\bba\bas\bsh\bh  to  read  and  execute commands from _\bf_\bi_\bl_\be instead of
       _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc.

       When b\bba\bas\bsh\bh is started non-interactively, to  run  a  shell  script,  for
       example, it looks for the variable B\bBA\bAS\bSH\bH_\b_E\bEN\bNV\bV 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.  B\bBa\bas\bsh\bh behaves as if the following com-
       mand were executed:
              if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
       but the value of the P\bPA\bAT\bTH\bH variable is not used to search for  the  file
       name.

       If  b\bba\bas\bsh\bh  is  invoked  with  the name s\bsh\bh, it tries to mimic the startup
       behavior of historical versions of s\bsh\bh 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  -\b--\b-l\blo\bog\bgi\bin\bn  option,
       it  first  attempts  to read and execute commands from _\b/_\be_\bt_\bc_\b/_\bp_\br_\bo_\bf_\bi_\bl_\be and
       _\b~_\b/_\b._\bp_\br_\bo_\bf_\bi_\bl_\be, in that order.  The  -\b--\b-n\bno\bop\bpr\bro\bof\bfi\bil\ble\be  option  may  be  used  to
       inhibit  this  behavior.  When invoked as an interactive shell with the
       name s\bsh\bh, b\bba\bas\bsh\bh looks for the variable E\bEN\bNV\bV, 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 s\bsh\bh does not attempt to read and exe-
       cute  commands from any other startup files, the -\b--\b-r\brc\bcf\bfi\bil\ble\be option has no
       effect.  A non-interactive shell invoked with  the  name  s\bsh\bh  does  not
       attempt  to  read  any  other  startup files.  When invoked as s\bsh\bh, b\bba\bas\bsh\bh
       enters _\bp_\bo_\bs_\bi_\bx mode after the startup files are read.

       When b\bba\bas\bsh\bh is started in _\bp_\bo_\bs_\bi_\bx mode, as with the  -\b--\b-p\bpo\bos\bsi\bix\bx  command  line
       option, it follows the POSIX standard for startup files.  In this mode,
       interactive shells expand the E\bEN\bNV\bV variable and commands  are  read  and
       executed  from  the  file  whose  name is the expanded value.  No other
       startup files are read.

       B\bBa\bas\bsh\bh attempts to determine when it is being run  by  the  remote  shell
       daemon,  usually  _\br_\bs_\bh_\bd.  If b\bba\bas\bsh\bh determines it is being run by _\br_\bs_\bh_\bd, it
       reads and executes commands from _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc, if that file exists and  is
       readable.  It will not do this if invoked as s\bsh\bh.  The -\b--\b-n\bno\bor\brc\bc option may
       be used to inhibit this behavior, and the -\b--\b-r\brc\bcf\bfi\bil\ble\be option may  be  used
       to  force  another  file to be read, but _\br_\bs_\bh_\bd does not 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 -\b-p\bp option is not supplied, no startup
       files are read, shell functions are not inherited from the environment,
       the  S\bSH\bHE\bEL\bLL\bLO\bOP\bPT\bTS\bS  variable, if it appears in the environment, is ignored,
       and the effective user id is set to the real user id.  If the -\b-p\bp option
       is  supplied  at  invocation, the startup behavior is the same, but the
       effective user id is not reset.

D\bDE\bEF\bFI\bIN\bNI\bIT\bTI\bIO\bON\bNS\bS
       The following definitions are used throughout the rest  of  this  docu-
       ment.
       b\bbl\bla\ban\bnk\bk  A space or tab.
       w\bwo\bor\brd\bd   A  sequence  of  characters  considered  as a single unit by the
              shell.  Also known as a t\bto\bok\bke\ben\bn.
       n\bna\bam\bme\be   A _\bw_\bo_\br_\bd consisting only of  alphanumeric  characters  and  under-
              scores,  and beginning with an alphabetic character or an under-
              score.  Also referred to as an i\bid\bde\ben\bnt\bti\bif\bfi\bie\ber\br.
       m\bme\bet\bta\bac\bch\bha\bar\bra\bac\bct\bte\ber\br
              A character that, when unquoted, separates words.   One  of  the
              following:
              |\b|  &\b& ;\b; (\b( )\b) <\b< >\b> s\bsp\bpa\bac\bce\be t\bta\bab\bb
       c\bco\bon\bnt\btr\bro\bol\bl o\bop\bpe\ber\bra\bat\bto\bor\br
              A _\bt_\bo_\bk_\be_\bn that performs a control function.  It is one of the fol-
              lowing symbols:
              |\b||\b| &\b& &\b&&\b& ;\b; ;\b;;\b; (\b( )\b) |\b| <\b<n\bne\bew\bwl\bli\bin\bne\be>\b>

R\bRE\bES\bSE\bER\bRV\bVE\bED\bD W\bWO\bOR\bRD\bDS\bS
       _\bR_\be_\bs_\be_\br_\bv_\be_\bd _\bw_\bo_\br_\bd_\bs 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 S\bSH\bHE\bEL\bLL\bL G\bGR\bRA\bAM\bMM\bMA\bAR\bR below) or  the  third
       word of a c\bca\bas\bse\be or f\bfo\bor\br command:

       !\b!  c\bca\bas\bse\be  d\bdo\bo d\bdo\bon\bne\be e\bel\bli\bif\bf e\bel\bls\bse\be e\bes\bsa\bac\bc f\bfi\bi f\bfo\bor\br f\bfu\bun\bnc\bct\bti\bio\bon\bn i\bif\bf i\bin\bn s\bse\bel\ble\bec\bct\bt t\bth\bhe\ben\bn u\bun\bnt\bti\bil\bl
       w\bwh\bhi\bil\ble\be {\b{ }\b} t\bti\bim\bme\be [\b[[\b[ ]\b]]\b]

S\bSH\bHE\bEL\bLL\bL G\bGR\bRA\bAM\bMM\bMA\bAR\bR
   S\bSi\bim\bmp\bpl\ble\be C\bCo\bom\bmm\bma\ban\bnd\bds\bs
       A _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd is a sequence of optional  variable  assignments  fol-
       lowed  by  b\bbl\bla\ban\bnk\bk-separated  words and redirections, and terminated by a
       _\bc_\bo_\bn_\bt_\br_\bo_\bl _\bo_\bp_\be_\br_\ba_\bt_\bo_\br.  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 _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd is its exit status,  or  128+_\bn  if
       the command is terminated by signal _\bn.

   P\bPi\bip\bpe\bel\bli\bin\bne\bes\bs
       A _\bp_\bi_\bp_\be_\bl_\bi_\bn_\be is a sequence of one or more commands separated by the char-
       acter |\b|.  The format for a pipeline is:

              [t\bti\bim\bme\be [-\b-p\bp]] [ ! ] _\bc_\bo_\bm_\bm_\ba_\bn_\bd [ |\b| _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2 ... ]

       The standard output of _\bc_\bo_\bm_\bm_\ba_\bn_\bd is connected via a pipe to the  standard
       input  of  _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2.   This connection is performed before any redirec-
       tions specified by the command (see R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN below).

       The return status of a pipeline is the exit status of the last command,
       unless  the  p\bpi\bip\bpe\bef\bfa\bai\bil\bl  option  is enabled.  If p\bpi\bip\bpe\bef\bfa\bai\bil\bl 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 !\b!  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  t\bti\bim\bme\be 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 -\b-p\bp option changes the output format to that
       specified by POSIX.  The T\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT variable may be  set  to  a  format
       string  that  specifies how the timing information should be displayed;
       see the description of T\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT under S\bSh\bhe\bel\bll\bl V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs below.

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

   L\bLi\bis\bst\bts\bs
       A  _\bl_\bi_\bs_\bt  is a sequence of one or more pipelines separated by one of the
       operators ;\b;, &\b&, &\b&&\b&, or |\b||\b|, and optionally terminated by one of ;\b;, &\b&, or
       <\b<n\bne\bew\bwl\bli\bin\bne\be>\b>.

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

       A sequence of one or more newlines may appear in a _\bl_\bi_\bs_\bt  instead  of  a
       semicolon to delimit commands.

       If  a  command  is terminated by the control operator &\b&, the shell exe-
       cutes the command in the _\bb_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd in a subshell.  The shell does  not
       wait  for  the command to finish, and the return status is 0.  Commands
       separated by a ;\b; 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.

       The control operators &\b&&\b& and |\b||\b| denote AND lists and OR lists,  respec-
       tively.  An AND list has the form

              _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b1 &\b&&\b& _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2

       _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2  is  executed if, and only if, _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b1 returns an exit status
       of zero.

       An OR list has the form

              _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b1 |\b||\b| _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2


       _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2 is executed if and only if _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b1 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.

   C\bCo\bom\bmp\bpo\bou\bun\bnd\bd C\bCo\bom\bmm\bma\ban\bnd\bds\bs
       A _\bc_\bo_\bm_\bp_\bo_\bu_\bn_\bd _\bc_\bo_\bm_\bm_\ba_\bn_\bd is one of the following:

       (_\bl_\bi_\bs_\bt) _\bl_\bi_\bs_\bt is executed in a subshell environment (see  C\bCO\bOM\bMM\bMA\bAN\bND\bD  E\bEX\bXE\bEC\bCU\bU-\b-
              T\bTI\bIO\bON\bN  E\bEN\bNV\bVI\bIR\bRO\bON\bNM\bME\bEN\bNT\bT 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 _\bl_\bi_\bs_\bt.

       { _\bl_\bi_\bs_\bt; }
              _\bl_\bi_\bs_\bt is simply executed in the current shell environment.   _\bl_\bi_\bs_\bt
              must  be  terminated with a newline or semicolon.  This is known
              as a _\bg_\br_\bo_\bu_\bp _\bc_\bo_\bm_\bm_\ba_\bn_\bd.  The return status is  the  exit  status  of
              _\bl_\bi_\bs_\bt.   Note that unlike the metacharacters (\b( and )\b), {\b{ and }\b} are
              _\br_\be_\bs_\be_\br_\bv_\be_\bd _\bw_\bo_\br_\bd_\bs 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 _\bl_\bi_\bs_\bt by whitespace.

       ((_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn))
              The _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn is evaluated according  to  the  rules  described
              below  under A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN.  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 l\ble\bet\bt "\b"_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn"\b".

       [\b[[\b[ _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn ]\b]]\b]
              Return  a  status  of  0 or 1 depending on the evaluation of the
              conditional expression _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn.  Expressions are composed  of
              the  primaries  described  below  under C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS.
              Word splitting and pathname expansion are not performed  on  the
              words  between  the  [\b[[\b[  and  ]\b]]\b]; tilde expansion, parameter and
              variable expansion, arithmetic expansion, command  substitution,
              process  substitution,  and quote removal are performed.  Condi-
              tional operators such as -\b-f\bf must be unquoted to be recognized as
              primaries.

              When  the  =\b==\b= and !\b!=\b= operators are used, the string to the right
              of the operator is considered a pattern and matched according to
              the  rules  described  below under P\bPa\bat\btt\bte\ber\brn\bn M\bMa\bat\btc\bch\bhi\bin\bng\bg.  The return
              value is 0 if the string matches or does not match the  pattern,
              respectively,  and  1 otherwise.  Any part of the pattern may be
              quoted to force it to be matched as a string.

              An additional binary operator, =\b=~\b~, is available, with  the  same
              precedence  as  =\b==\b=  and  !\b!=\b=.  When it is used, the string to the
              right of the operator is considered an extended regular  expres-
              sion and matched accordingly (as in _\br_\be_\bg_\be_\bx(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  n\bno\boc\bca\bas\bse\beg\bgl\blo\bob\bb
              is enabled, the match is performed without regard to the case of
              alphabetic  characters.   Substrings  matched  by  parenthesized
              subexpressions  within  the  regular expression are saved in the
              array variable B\bBA\bAS\bSH\bH_\b_R\bRE\bEM\bMA\bAT\bTC\bCH\bH.  The element of  B\bBA\bAS\bSH\bH_\b_R\bRE\bEM\bMA\bAT\bTC\bCH\bH  with
              index 0 is the portion of the string matching the entire regular
              expression.  The element of B\bBA\bAS\bSH\bH_\b_R\bRE\bEM\bMA\bAT\bTC\bCH\bH with  index  _\bn  is  the
              portion  of the string matching the _\bnth parenthesized subexpres-
              sion.

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

              (\b( _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn )\b)
                     Returns  the  value  of  _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn.  This may be used to
                     override the normal precedence of operators.
              !\b! _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn
                     True if _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn is false.
              _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b1 &\b&&\b& _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b2
                     True if both _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b1 and _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b2 are true.
              _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b1 |\b||\b| _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b2
                     True if either _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b1 or _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b2 is true.

              The &\b&&\b& and |\b||\b| operators do not evaluate _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b2 if the value
              of  _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\b1  is  sufficient to determine the return value of
              the entire conditional expression.

       f\bfo\bor\br _\bn_\ba_\bm_\be [ i\bin\bn _\bw_\bo_\br_\bd ] ; d\bdo\bo _\bl_\bi_\bs_\bt ; d\bdo\bon\bne\be
              The list of words following i\bin\bn is expanded, generating a list of
              items.  The variable _\bn_\ba_\bm_\be is set to each element of this list in
              turn, and _\bl_\bi_\bs_\bt is executed each time.  If the i\bin\bn _\bw_\bo_\br_\bd  is  omit-
              ted,  the  f\bfo\bor\br  command  executes  _\bl_\bi_\bs_\bt once for each positional
              parameter that is set (see P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS below).  The return status
              is  the  exit  status of the last command that executes.  If the
              expansion of the items following i\bin\bn results in an empty list, no
              commands are executed, and the return status is 0.

       f\bfo\bor\br (( _\be_\bx_\bp_\br_\b1 ; _\be_\bx_\bp_\br_\b2 ; _\be_\bx_\bp_\br_\b3 )) ; d\bdo\bo _\bl_\bi_\bs_\bt ; d\bdo\bon\bne\be
              First, the arithmetic expression _\be_\bx_\bp_\br_\b1 is evaluated according to
              the rules described  below  under  A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC  E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN.   The
              arithmetic  expression  _\be_\bx_\bp_\br_\b2 is then evaluated repeatedly until
              it evaluates to zero.  Each time _\be_\bx_\bp_\br_\b2 evaluates to  a  non-zero
              value,  _\bl_\bi_\bs_\bt  is executed and the arithmetic expression _\be_\bx_\bp_\br_\b3 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 _\bl_\bi_\bs_\bt that is executed, or false if any of the expres-
              sions is invalid.

       s\bse\bel\ble\bec\bct\bt _\bn_\ba_\bm_\be [ i\bin\bn _\bw_\bo_\br_\bd ] ; d\bdo\bo _\bl_\bi_\bs_\bt ; d\bdo\bon\bne\be
              The list of words following i\bin\bn 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 i\bin\bn _\bw_\bo_\br_\bd is omitted,
              the positional parameters are printed  (see  P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS  below).
              The  P\bPS\bS3\b3 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 _\bn_\ba_\bm_\be is set to
              that word.  If the line is  empty,  the  words  and  prompt  are
              displayed  again.   If  EOF is read, the command completes.  Any
              other value read causes _\bn_\ba_\bm_\be to be set to null.  The  line  read
              is saved in the variable R\bRE\bEP\bPL\bLY\bY.  The _\bl_\bi_\bs_\bt is executed after each
              selection until a b\bbr\bre\bea\bak\bk command is executed.  The exit status of
              s\bse\bel\ble\bec\bct\bt  is the exit status of the last command executed in _\bl_\bi_\bs_\bt,
              or zero if no commands were executed.

       c\bca\bas\bse\be _\bw_\bo_\br_\bd i\bin\bn [ [(] _\bp_\ba_\bt_\bt_\be_\br_\bn [ |\b| _\bp_\ba_\bt_\bt_\be_\br_\bn ] ... ) _\bl_\bi_\bs_\bt ;; ] ... e\bes\bsa\bac\bc
              A c\bca\bas\bse\be command first expands _\bw_\bo_\br_\bd, and tries to match it against
              each _\bp_\ba_\bt_\bt_\be_\br_\bn in turn, using the same matching rules as for path-
              name expansion (see P\bPa\bat\bth\bhn\bna\bam\bme\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn below).  When a match  is
              found,  the  corresponding  _\bl_\bi_\bs_\bt  is  executed.  After the first
              match, no subsequent matches are attempted.  The exit status  is
              zero if no pattern matches.  Otherwise, it is the exit status of
              the last command executed in _\bl_\bi_\bs_\bt.

       i\bif\bf _\bl_\bi_\bs_\bt; t\bth\bhe\ben\bn _\bl_\bi_\bs_\bt_\b; [ e\bel\bli\bif\bf _\bl_\bi_\bs_\bt; t\bth\bhe\ben\bn _\bl_\bi_\bs_\bt; ] ... [ e\bel\bls\bse\be _\bl_\bi_\bs_\bt; ] f\bfi\bi
              The i\bif\bf _\bl_\bi_\bs_\bt is executed.  If its exit status is zero,  the  t\bth\bhe\ben\bn
              _\bl_\bi_\bs_\bt  is  executed.   Otherwise,  each  e\bel\bli\bif\bf _\bl_\bi_\bs_\bt is executed in
              turn, and if its exit status is  zero,  the  corresponding  t\bth\bhe\ben\bn
              _\bl_\bi_\bs_\bt is executed and the command completes.  Otherwise, the e\bel\bls\bse\be
              _\bl_\bi_\bs_\bt is executed, if present.  The exit status is the exit  sta-
              tus of the last command executed, or zero if no condition tested
              true.

       w\bwh\bhi\bil\ble\be _\bl_\bi_\bs_\bt; d\bdo\bo _\bl_\bi_\bs_\bt; d\bdo\bon\bne\be
       u\bun\bnt\bti\bil\bl _\bl_\bi_\bs_\bt; d\bdo\bo _\bl_\bi_\bs_\bt; d\bdo\bon\bne\be
              The w\bwh\bhi\bil\ble\be command continuously executes the d\bdo\bo _\bl_\bi_\bs_\bt as  long  as
              the  last  command  in _\bl_\bi_\bs_\bt returns an exit status of zero.  The
              u\bun\bnt\bti\bil\bl command is identical to the w\bwh\bhi\bil\ble\be command, except that the
              test  is  negated;  the  d\bdo\bo _\bl_\bi_\bs_\bt is executed as long as the last
              command in _\bl_\bi_\bs_\bt returns a non-zero exit status.  The exit status
              of  the  w\bwh\bhi\bil\ble\be and u\bun\bnt\bti\bil\bl commands is the exit status of the last
              d\bdo\bo _\bl_\bi_\bs_\bt command executed, or zero if none was executed.

   S\bSh\bhe\bel\bll\bl F\bFu\bun\bnc\bct\bti\bio\bon\bn D\bDe\bef\bfi\bin\bni\bit\bti\bio\bon\bns\bs
       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:

       [ f\bfu\bun\bnc\bct\bti\bio\bon\bn ] _\bn_\ba_\bm_\be () _\bc_\bo_\bm_\bp_\bo_\bu_\bn_\bd_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd [_\br_\be_\bd_\bi_\br_\be_\bc_\bt_\bi_\bo_\bn]
              This defines a function named _\bn_\ba_\bm_\be.  The reserved word  f\bfu\bun\bnc\bct\bti\bio\bon\bn
              is  optional.   If  the  f\bfu\bun\bnc\bct\bti\bio\bon\bn reserved word is supplied, the
              parentheses are optional.  The _\bb_\bo_\bd_\by of the function is the  com-
              pound  command  _\bc_\bo_\bm_\bp_\bo_\bu_\bn_\bd_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd  (see C\bCo\bom\bmp\bpo\bou\bun\bnd\bd C\bCo\bom\bmm\bma\ban\bnd\bds\bs above).
              That command is usually a _\bl_\bi_\bs_\bt of commands between { and },  but
              may  be  any command listed under C\bCo\bom\bmp\bpo\bou\bun\bnd\bd C\bCo\bom\bmm\bma\ban\bnd\bds\bs above.  _\bc_\bo_\bm_\b-
              _\bp_\bo_\bu_\bn_\bd_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd is executed whenever _\bn_\ba_\bm_\be is specified as the name
              of  a  simple command.  Any redirections (see R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN 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 executed, the exit status of
              a function is the exit status of the last  command  executed  in
              the body.  (See F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS below.)

C\bCO\bOM\bMM\bME\bEN\bNT\bTS\bS
       In a non-interactive shell, or an interactive shell in which the i\bin\bnt\bte\ber\br-\b-
       a\bac\bct\bti\biv\bve\be_\b_c\bco\bom\bmm\bme\ben\bnt\bts\bs option to the  s\bsh\bho\bop\bpt\bt  builtin  is  enabled  (see  S\bSH\bHE\bEL\bLL\bL
       B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  below), a word beginning with #\b# causes that word and
       all remaining characters on that line to be  ignored.   An  interactive
       shell  without  the  i\bin\bnt\bte\ber\bra\bac\bct\bti\biv\bve\be_\b_c\bco\bom\bmm\bme\ben\bnt\bts\bs option enabled does not allow
       comments.  The i\bin\bnt\bte\ber\bra\bac\bct\bti\biv\bve\be_\b_c\bco\bom\bmm\bme\ben\bnt\bts\bs option is on by default in interac-
       tive shells.

Q\bQU\bUO\bOT\bTI\bIN\bNG\bG
       _\bQ_\bu_\bo_\bt_\bi_\bn_\bg  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 _\bm_\be_\bt_\ba_\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br_\bs listed above under D\bDE\bEF\bFI\bIN\bNI\bIT\bTI\bIO\bON\bNS\bS  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, the _\bh_\bi_\bs_\b-
       _\bt_\bo_\br_\by _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn character, usually !\b!, must be quoted to prevent  history
       expansion.

       There  are  three  quoting  mechanisms:  the  _\be_\bs_\bc_\ba_\bp_\be  _\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br, single
       quotes, and double quotes.

       A non-quoted backslash (\\b\) is the _\be_\bs_\bc_\ba_\bp_\be _\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br.  It  preserves  the
       literal value of the next character that follows, with the exception of
       <newline>.  If a \\b\<newline> pair appears,  and  the  backslash  is  not
       itself  quoted,  the \\b\<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 $\b$, `\b`, and \\b\.
       The characters $\b$ and `\b`  retain  their  special  meaning  within  double
       quotes.   The  backslash retains its special meaning only when followed
       by one of the following characters: $\b$, `\b`, "\b", \\b\, or <\b<n\bne\bew\bwl\bli\bin\bne\be>\b>.  A double
       quote  may  be quoted within double quotes by preceding it with a back-
       slash.  When command history is being used, the double quote may not be
       used to quote the history expansion character.

       The  special  parameters  *\b*  and  @\b@ have special meaning when in double
       quotes (see P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS below).

       Words of the form $\b$'_\bs_\bt_\br_\bi_\bn_\bg' are treated specially.  The word expands to
       _\bs_\bt_\br_\bi_\bn_\bg,  with  backslash-escaped characters replaced as specifed by the
       ANSI C standard.  Backslash escape sequences, if present,  are  decoded
       as follows:
              \\b\a\ba     alert (bell)
              \\b\b\bb     backspace
              \\b\e\be     an escape character
              \\b\f\bf     form feed
              \\b\n\bn     new line
              \\b\r\br     carriage return
              \\b\t\bt     horizontal tab
              \\b\v\bv     vertical tab
              \\b\\\b\     backslash
              \\b\'\b'     single quote
              \\b\_\bn_\bn_\bn   the  eight-bit  character  whose value is the octal value
                     _\bn_\bn_\bn (one to three digits)
              \\b\x\bx_\bH_\bH   the eight-bit character whose value  is  the  hexadecimal
                     value _\bH_\bH (one or two hex digits)
              \\b\c\bc_\bx    a control-_\bx 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  ($\b$)  will  cause  the
       string  to  be translated according to the current locale.  If the cur-
       rent locale is C\bC or P\bPO\bOS\bSI\bIX\bX, the dollar sign is ignored.  If  the  string
       is translated and replaced, the replacement is double-quoted.

P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS
       A  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an entity that stores values.  It can be a _\bn_\ba_\bm_\be, a num-
       ber, or one of the special characters listed below under S\bSp\bpe\bec\bci\bia\bal\bl P\bPa\bar\bra\bam\bm-\b-
       e\bet\bte\ber\brs\bs.   A _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be is a parameter denoted by a _\bn_\ba_\bm_\be.  A variable has a
       _\bv_\ba_\bl_\bu_\be and zero or more _\ba_\bt_\bt_\br_\bi_\bb_\bu_\bt_\be_\bs.  Attributes are assigned  using  the
       d\bde\bec\bcl\bla\bar\bre\be  builtin command (see d\bde\bec\bcl\bla\bar\bre\be below in S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS).

       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 u\bun\bns\bse\bet\bt builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

       A _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be may be assigned to by a statement of the form

              _\bn_\ba_\bm_\be=[_\bv_\ba_\bl_\bu_\be]

       If _\bv_\ba_\bl_\bu_\be is not given, the variable is assigned the null  string.   All
       _\bv_\ba_\bl_\bu_\be_\bs  undergo tilde expansion, parameter and variable expansion, com-
       mand substitution, arithmetic expansion, and quote removal (see  E\bEX\bXP\bPA\bAN\bN-\b-
       S\bSI\bIO\bON\bN below).  If the variable has its i\bin\bnt\bte\beg\bge\ber\br attribute set, then _\bv_\ba_\bl_\bu_\be
       is evaluated as an arithmetic expression even if the $((...)) expansion
       is  not  used  (see A\bAr\bri\bit\bth\bhm\bme\bet\bti\bic\bc E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn below).  Word splitting is not
       performed, with the exception of "\b"$\b$@\b@"\b" as explained below under  S\bSp\bpe\bec\bci\bia\bal\bl
       P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs.   Pathname  expansion  is not performed.  Assignment state-
       ments may also appear as arguments  to  the  a\bal\bli\bia\bas\bs,  d\bde\bec\bcl\bla\bar\bre\be,  t\bty\byp\bpe\bes\bse\bet\bt,
       e\bex\bxp\bpo\bor\brt\bt, r\bre\bea\bad\bdo\bon\bnl\bly\by, and l\blo\boc\bca\bal\bl builtin commands.

   P\bPo\bos\bsi\bit\bti\bio\bon\bna\bal\bl P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs
       A  _\bp_\bo_\bs_\bi_\bt_\bi_\bo_\bn_\ba_\bl  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  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 s\bse\bet\bt 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 F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS below).

       When a positional parameter consisting of more than a single  digit  is
       expanded, it must be enclosed in braces (see E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below).

   S\bSp\bpe\bec\bci\bia\bal\bl P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs
       The  shell  treats  several parameters specially.  These parameters may
       only be referenced; assignment to them is not allowed.
       *\b*      Expands to the positional parameters, starting from  one.   When
              the  expansion occurs within double quotes, it expands to a sin-
              gle word with the value of each parameter separated by the first
              character of the I\bIF\bFS\bS special variable.  That is, "$\b$*\b*" is equiva-
              lent to "$\b$1\b1_\bc$\b$2\b2_\bc.\b..\b..\b.", where _\bc is the first character of the value
              of  the I\bIF\bFS\bS variable.  If I\bIF\bFS\bS is unset, the parameters are sepa-
              rated by spaces.  If I\bIF\bFS\bS is  null,  the  parameters  are  joined
              without intervening separators.
       @\b@      Expands  to  the positional parameters, starting from one.  When
              the  expansion  occurs  within  double  quotes,  each  parameter
              expands to a separate word.  That is, "$\b$@\b@" is equivalent to "$\b$1\b1"
              "$\b$2\b2" ...  If the double-quoted expansion occurs within  a  word,
              the  expansion  of the first parameter is joined with the begin-
              ning part of the original word, and the expansion  of  the  last
              parameter  is  joined  with  the last part of the original word.
              When there are no positional parameters, "$\b$@\b@" and $\b$@\b@  expand  to
              nothing (i.e., they are removed).
       #\b#      Expands to the number of positional parameters in decimal.
       ?\b?      Expands  to  the status of the most recently executed foreground
              pipeline.
       -\b-      Expands to the current option flags as  specified  upon  invoca-
              tion,  by  the  s\bse\bet\bt  builtin  command, or those set by the shell
              itself (such as the -\b-i\bi option).
       $\b$      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.
       !\b!      Expands to the process ID of the most  recently  executed  back-
              ground (asynchronous) command.
       0\b0      Expands  to  the name of the shell or shell script.  This is set
              at shell initialization.  If b\bba\bas\bsh\bh is invoked with a file of com-
              mands,  $\b$0\b0  is set to the name of that file.  If b\bba\bas\bsh\bh is started
              with the -\b-c\bc option, then $\b$0\b0 is set to the first  argument  after
              the  string to be executed, if one is present.  Otherwise, it is
              set to the file name used to invoke b\bba\bas\bsh\bh, as given  by  argument
              zero.
       _\b_      At  shell startup, set to the absolute file name of the shell or
              shell script being executed as  passed  in  the  argument  list.
              Subsequently,  expands to the last argument to the previous com-
              mand, after expansion.  Also set to the full file name  of  each
              command  executed and placed in the environment exported to that
              command.  When checking mail, this parameter holds the  name  of
              the mail file currently being checked.

   S\bSh\bhe\bel\bll\bl V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs
       The following variables are set by the shell:

       B\bBA\bAS\bSH\bH   Expands  to  the  full file name used to invoke this instance of
              b\bba\bas\bsh\bh.
       B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGC\bC
              An array variable whose values are the number of  parameters  in
              each frame of the current bash execution call stack.  The number
              of parameters to  the  current  subroutine  (shell  function  or
              script  executed  with  .\b. or s\bso\bou\bur\brc\bce\be) is at the top of the stack.
              When a subroutine is executed, the number of  parameters  passed
              is pushed onto B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGC\bC.
       B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGV\bV
              An  array  variable containing all of the parameters in the cur-
              rent bash 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 B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGV\bV.
       B\bBA\bAS\bSH\bH_\b_C\bCO\bOM\bMM\bMA\bAN\bND\bD
              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.
       B\bBA\bAS\bSH\bH_\b_E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN_\b_S\bST\bTR\bRI\bIN\bNG\bG
              The command argument to the -\b-c\bc invocation option.
       B\bBA\bAS\bSH\bH_\b_L\bLI\bIN\bNE\bEN\bNO\bO
              An array variable whose members are the line numbers  in  source
              files    corresponding    to    each    member    of   F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE.
              $\b${\b{B\bBA\bAS\bSH\bH_\b_L\bLI\bIN\bNE\bEN\bNO\bO[\b[_\b$_\bi]\b]}\b} is the line number in the source  file  where
              $\b${\b{F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE[\b[_\b$_\bi  _\b+  _\b1]\b]}\b} was called.  The corresponding source file
              name is $\b${\b{B\bBA\bAS\bSH\bH_\b_S\bSO\bOU\bUR\bRC\bCE\bE[\b[_\b$_\bi _\b+ _\b1]\b]}\b}.\b.  U\bUs\bse\be L\bLI\bIN\bNE\bEN\bNO\bO t\bto\bo o\bob\bbt\bta\bai\bin\bn  t\bth\bhe\be  c\bcu\bur\br-\b-
              r\bre\ben\bnt\bt l\bli\bin\bne\be n\bnu\bum\bmb\bbe\ber\br.\b.
       B\bBA\bAS\bSH\bH_\b_R\bRE\bEM\bMA\bAT\bTC\bCH\bH
              An  array  variable  whose members are assigned by the =\b=~\b~ binary
              operator to the [\b[[\b[ conditional command.  The element with  index
              0  is  the  portion  of  the  string matching the entire regular
              expression.  The element with index _\bn  is  the  portion  of  the
              string matching the _\bnth parenthesized subexpression.  This vari-
              able is read-only.
       B\bBA\bAS\bSH\bH_\b_S\bSO\bOU\bUR\bRC\bCE\bE
              An array variable whose members are the source filenames  corre-
              sponding to the elements in the F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE array variable.
       B\bBA\bAS\bSH\bH_\b_S\bSU\bUB\bBS\bSH\bHE\bEL\bLL\bL
              Incremented  by one each time a subshell or subshell environment
              is spawned.  The initial value is 0.
       B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO
              A readonly array variable whose members hold version information
              for  this  instance  of  b\bba\bas\bsh\bh.  The values assigned to the array
              members are as follows:
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[0]\b]        The major version number (the  _\br_\be_\bl_\be_\ba_\bs_\be).
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[1]\b]        The  minor version number (the _\bv_\be_\br_\bs_\bi_\bo_\bn).
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[2]\b]        The patch level.
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[3]\b]        The build version.
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[4]\b]        The release status (e.g., _\bb_\be_\bt_\ba_\b1).
              B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIN\bNF\bFO\bO[\b[5]\b]        The value of M\bMA\bAC\bCH\bHT\bTY\bYP\bPE\bE.

       B\bBA\bAS\bSH\bH_\b_V\bVE\bER\bRS\bSI\bIO\bON\bN
              Expands to a string describing the version of this  instance  of
              b\bba\bas\bsh\bh.

       C\bCO\bOM\bMP\bP_\b_C\bCW\bWO\bOR\bRD\bD
              An  index  into $\b${\b{C\bCO\bOM\bMP\bP_\b_W\bWO\bOR\bRD\bDS\bS}\b} of the word containing the current
              cursor position.  This variable is available only in shell func-
              tions  invoked  by  the  programmable completion facilities (see
              P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn below).

       C\bCO\bOM\bMP\bP_\b_L\bLI\bIN\bNE\bE
              The current command line.  This variable is  available  only  in
              shell  functions  and  external  commands  invoked  by  the pro-
              grammable completion  facilities  (see  P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be  C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn
              below).

       C\bCO\bOM\bMP\bP_\b_P\bPO\bOI\bIN\bNT\bT
              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 $\b${\b{#\b#C\bCO\bOM\bMP\bP_\b_L\bLI\bIN\bNE\bE}\b}.  This  variable  is  available  only  in
              shell  functions  and  external  commands  invoked  by  the pro-
              grammable completion  facilities  (see  P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be  C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn
              below).

       C\bCO\bOM\bMP\bP_\b_W\bWO\bOR\bRD\bDB\bBR\bRE\bEA\bAK\bKS\bS
              The  set  of characters that the Readline library treats as word
              separators when performing word completion.  If  C\bCO\bOM\bMP\bP_\b_W\bWO\bOR\bRD\bDB\bBR\bRE\bEA\bAK\bKS\bS
              is  unset, it loses its special properties, even if it is subse-
              quently reset.

       C\bCO\bOM\bMP\bP_\b_W\bWO\bOR\bRD\bDS\bS
              An array variable (see A\bAr\brr\bra\bay\bys\bs below) consisting of the  individ-
              ual  words in the current command line.  This variable is avail-
              able only in shell functions invoked by the programmable comple-
              tion facilities (see P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn below).

       D\bDI\bIR\bRS\bST\bTA\bAC\bCK\bK
              An array variable (see A\bAr\brr\bra\bay\bys\bs below) containing the current con-
              tents of the directory stack.  Directories appear in  the  stack
              in  the order they are displayed by the d\bdi\bir\brs\bs builtin.  Assigning
              to members of this array variable may be used to modify directo-
              ries  already in the stack, but the p\bpu\bus\bsh\bhd\bd and p\bpo\bop\bpd\bd builtins must
              be used to add and remove directories.  Assignment to this vari-
              able  will  not  change  the  current directory.  If D\bDI\bIR\bRS\bST\bTA\bAC\bCK\bK is
              unset, it loses its special properties, even  if  it  is  subse-
              quently reset.

       E\bEU\bUI\bID\bD   Expands  to  the effective user ID of the current user, initial-
              ized at shell startup.  This variable is readonly.

       F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE
              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  is  "main".  This variable exists only when a
              shell function is executing.  Assignments to  F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE  have  no
              effect  and  return  an  error status.  If F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE is unset, it
              loses its special properties, even if it is subsequently  reset.

       G\bGR\bRO\bOU\bUP\bPS\bS An  array  variable  containing  the list of groups of which the
              current user is a member.  Assignments to G\bGR\bRO\bOU\bUP\bPS\bS have no  effect
              and  return  an  error status.  If G\bGR\bRO\bOU\bUP\bPS\bS is unset, it loses its
              special properties, even if it is subsequently reset.

       H\bHI\bIS\bST\bTC\bCM\bMD\bD
              The history number, or index in the history list, of the current
              command.   If H\bHI\bIS\bST\bTC\bCM\bMD\bD is unset, it loses its special properties,
              even if it is subsequently reset.

       H\bHO\bOS\bST\bTN\bNA\bAM\bME\bE
              Automatically set to the name of the current host.

       H\bHO\bOS\bST\bTT\bTY\bYP\bPE\bE
              Automatically set to a string that uniquely describes  the  type
              of  machine  on which b\bba\bas\bsh\bh is executing.  The default is system-
              dependent.

       L\bLI\bIN\bNE\bEN\bNO\bO 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 L\bLI\bIN\bNE\bEN\bNO\bO is unset, it loses its special proper-
              ties, even if it is subsequently reset.

       M\bMA\bAC\bCH\bHT\bTY\bYP\bPE\bE
              Automatically  set  to  a string that fully describes the system
              type on which b\bba\bas\bsh\bh is executing, in the  standard  GNU  _\bc_\bp_\bu_\b-_\bc_\bo_\bm_\b-
              _\bp_\ba_\bn_\by_\b-_\bs_\by_\bs_\bt_\be_\bm format.  The default is system-dependent.

       O\bOL\bLD\bDP\bPW\bWD\bD The previous working directory as set by the c\bcd\bd command.

       O\bOP\bPT\bTA\bAR\bRG\bG The  value  of the last option argument processed by the g\bge\bet\bto\bop\bpt\bts\bs
              builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

       O\bOP\bPT\bTI\bIN\bND\bD The index of the next argument to be processed  by  the  g\bge\bet\bto\bop\bpt\bts\bs
              builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

       O\bOS\bST\bTY\bYP\bPE\bE Automatically  set to a string that describes the operating sys-
              tem on which b\bba\bas\bsh\bh is executing.  The  default  is  system-depen-
              dent.

       P\bPI\bIP\bPE\bES\bST\bTA\bAT\bTU\bUS\bS
              An  array  variable (see A\bAr\brr\bra\bay\bys\bs 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).

       P\bPP\bPI\bID\bD   The  process  ID  of the shell's parent.  This variable is read-
              only.

       P\bPW\bWD\bD    The current working directory as set by the c\bcd\bd command.

       R\bRA\bAN\bND\bDO\bOM\bM 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 R\bRA\bAN\bND\bDO\bOM\bM.  If R\bRA\bAN\bND\bDO\bOM\bM is unset,
              it  loses  its  special  properties,  even if it is subsequently
              reset.

       R\bRE\bEP\bPL\bLY\bY  Set to the line of input read by the r\bre\bea\bad\bd builtin  command  when
              no arguments are supplied.

       S\bSE\bEC\bCO\bON\bND\bDS\bS
              Each  time  this  parameter is referenced, the number of seconds
              since shell invocation is returned.  If a value is  assigned  to
              S\bSE\bEC\bCO\bON\bND\bDS\bS,  the  value  returned upon subsequent references is the
              number of seconds since the assignment plus the value  assigned.
              If S\bSE\bEC\bCO\bON\bND\bDS\bS is unset, it loses its special properties, even if it
              is subsequently reset.

       S\bSH\bHE\bEL\bLL\bLO\bOP\bPT\bTS\bS
              A colon-separated list of enabled shell options.  Each  word  in
              the  list  is  a  valid  argument  for  the -\b-o\bo option to the s\bse\bet\bt
              builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).  The options
              appearing  in  S\bSH\bHE\bEL\bLL\bLO\bOP\bPT\bTS\bS are those reported as _\bo_\bn by s\bse\bet\bt -\b-o\bo.  If
              this variable is in the environment when b\bba\bas\bsh\bh  starts  up,  each
              shell  option  in  the  list  will be enabled before reading any
              startup files.  This variable is read-only.

       S\bSH\bHL\bLV\bVL\bL  Incremented by one each time an instance of b\bba\bas\bsh\bh is started.

       U\bUI\bID\bD    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, b\bba\bas\bsh\bh
       assigns a default value to a variable; these cases are noted below.

       B\bBA\bAS\bSH\bH_\b_E\bEN\bNV\bV
              If this parameter is set when b\bba\bas\bsh\bh is executing a shell  script,
              its  value  is  interpreted as a filename containing commands to
              initialize the shell, as in _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc.  The value of B\bBA\bAS\bSH\bH_\b_E\bEN\bNV\bV is
              subjected  to  parameter  expansion,  command  substitution, and
              arithmetic expansion before being interpreted as  a  file  name.
              P\bPA\bAT\bTH\bH is not used to search for the resultant file name.
       C\bCD\bDP\bPA\bAT\bTH\bH The  search  path for the c\bcd\bd command.  This is a colon-separated
              list of directories in which the  shell  looks  for  destination
              directories  specified  by  the  c\bcd\bd  command.  A sample value is
              ".:~:/usr".
       C\bCO\bOL\bLU\bUM\bMN\bNS\bS
              Used by the s\bse\bel\ble\bec\bct\bt builtin command  to  determine  the  terminal
              width  when  printing  selection  lists.  Automatically set upon
              receipt of a SIGWINCH.
       C\bCO\bOM\bMP\bPR\bRE\bEP\bPL\bLY\bY
              An array variable from which b\bba\bas\bsh\bh reads the possible completions
              generated  by  a shell function invoked by the programmable com-
              pletion facility (see P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn below).
       E\bEM\bMA\bAC\bCS\bS  If b\bba\bas\bsh\bh 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.
       F\bFC\bCE\bED\bDI\bIT\bT The default editor for the f\bfc\bc builtin command.
       F\bFI\bIG\bGN\bNO\bOR\bRE\bE
              A colon-separated list of suffixes  to  ignore  when  performing
              filename completion (see R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE below).  A filename whose suf-
              fix matches one of the entries in F\bFI\bIG\bGN\bNO\bOR\bRE\bE is excluded  from  the
              list of matched filenames.  A sample value is ".o:~".
       G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE
              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
              G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE, it is removed from the list of matches.
       H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL
              A colon-separated list of values controlling  how  commands  are
              saved  on  the  history  list.   If  the list of values includes
              _\bi_\bg_\bn_\bo_\br_\be_\bs_\bp_\ba_\bc_\be, lines which begin with a s\bsp\bpa\bac\bce\be  character  are  not
              saved  in  the history list.  A value of _\bi_\bg_\bn_\bo_\br_\be_\bd_\bu_\bp_\bs causes lines
              matching the previous history entry to not be saved.  A value of
              _\bi_\bg_\bn_\bo_\br_\be_\bb_\bo_\bt_\bh is shorthand for _\bi_\bg_\bn_\bo_\br_\be_\bs_\bp_\ba_\bc_\be and _\bi_\bg_\bn_\bo_\br_\be_\bd_\bu_\bp_\bs.  A value
              of _\be_\br_\ba_\bs_\be_\bd_\bu_\bp_\bs 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  H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL  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  H\bHI\bIS\bST\bTI\bIG\bGN\bNO\bOR\bRE\bE.  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 H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL.
       H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE
              The name of the file in which command history is saved (see H\bHI\bIS\bS-\b-
              T\bTO\bOR\bRY\bY below).  The default value is _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bh_\bi_\bs_\bt_\bo_\br_\by.   If  unset,
              the  command  history  is  not  saved  when an interactive shell
              exits.
       H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bES\bSI\bIZ\bZE\bE
              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.   The  default  value  is  500.  The history file is also
              truncated to this size after  writing  it  when  an  interactive
              shell exits.
       H\bHI\bIS\bST\bTI\bIG\bGN\bNO\bOR\bRE\bE
              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  `*\b*'  is  appended).   Each  pattern  is
              tested  against  the line after the checks specified by H\bHI\bIS\bST\bTC\bCO\bON\bN-\b-
              T\bTR\bRO\bOL\bL are applied.  In  addition  to  the  normal  shell  pattern
              matching characters, `&\b&' matches the previous history line.  `&\b&'
              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 H\bHI\bIS\bST\bTI\bIG\bGN\bNO\bOR\bRE\bE.
       H\bHI\bIS\bST\bTS\bSI\bIZ\bZE\bE
              The  number  of commands to remember in the command history (see
              H\bHI\bIS\bST\bTO\bOR\bRY\bY below).  The default value is 500.
       H\bHI\bIS\bST\bTT\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT
              If this variable is set and not null, its value  is  used  as  a
              format string for _\bs_\bt_\br_\bf_\bt_\bi_\bm_\be(3) to print the time stamp associated
              with each history entry displayed by the  h\bhi\bis\bst\bto\bor\bry\by  builtin.   If
              this  variable  is  set,  time stamps are written to the history
              file so they may be preserved across shell sessions.
       H\bHO\bOM\bME\bE   The home directory of the current user; the default argument for
              the c\bcd\bd builtin command.  The value of this variable is also used
              when performing tilde expansion.
       H\bHO\bOS\bST\bTF\bFI\bIL\bLE\bE
              Contains the name of a file in the  same  format  as  _\b/_\be_\bt_\bc_\b/_\bh_\bo_\bs_\bt_\bs
              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, b\bba\bas\bsh\bh adds the contents  of
              the  new file to the existing list.  If H\bHO\bOS\bST\bTF\bFI\bIL\bLE\bE is set, but has
              no value, b\bba\bas\bsh\bh attempts to read _\b/_\be_\bt_\bc_\b/_\bh_\bo_\bs_\bt_\bs to obtain the list of
              possible  hostname  completions.   When  H\bHO\bOS\bST\bTF\bFI\bIL\bLE\bE  is unset, the
              hostname list is cleared.
       I\bIF\bFS\bS    The _\bI_\bn_\bt_\be_\br_\bn_\ba_\bl _\bF_\bi_\be_\bl_\bd _\bS_\be_\bp_\ba_\br_\ba_\bt_\bo_\br that is  used  for  word  splitting
              after  expansion  and  to  split  lines into words with the r\bre\bea\bad\bd
              builtin  command.   The  default  value  is  ``<space><tab><new-
              line>''.
       I\bIG\bGN\bNO\bOR\bRE\bEE\bEO\bOF\bF
              Controls the action of an interactive shell on receipt of an E\bEO\bOF\bF
              character as the sole input.  If set, the value is the number of
              consecutive  E\bEO\bOF\bF  characters  which  must  be typed as the first
              characters on an input line before b\bba\bas\bsh\bh 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,  E\bEO\bOF\bF  signifies  the
              end of input to the shell.
       I\bIN\bNP\bPU\bUT\bTR\bRC\bC
              The  filename  for  the  r\bre\bea\bad\bdl\bli\bin\bne\be  startup  file, overriding the
              default of _\b~_\b/_\b._\bi_\bn_\bp_\bu_\bt_\br_\bc (see R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE below).
       L\bLA\bAN\bNG\bG   Used to determine the  locale  category  for  any  category  not
              specifically selected with a variable starting with L\bLC\bC_\b_.
       L\bLC\bC_\b_A\bAL\bLL\bL This  variable  overrides  the  value  of L\bLA\bAN\bNG\bG and any other L\bLC\bC_\b_
              variable specifying a locale category.
       L\bLC\bC_\b_C\bCO\bOL\bLL\bLA\bAT\bTE\bE
              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.
       L\bLC\bC_\b_C\bCT\bTY\bYP\bPE\bE
              This  variable  determines  the interpretation of characters and
              the behavior of character classes within pathname expansion  and
              pattern matching.
       L\bLC\bC_\b_M\bME\bES\bSS\bSA\bAG\bGE\bES\bS
              This  variable  determines  the locale used to translate double-
              quoted strings preceded by a $\b$.
       L\bLC\bC_\b_N\bNU\bUM\bME\bER\bRI\bIC\bC
              This variable determines the locale  category  used  for  number
              formatting.
       L\bLI\bIN\bNE\bES\bS  Used  by  the  s\bse\bel\ble\bec\bct\bt  builtin  command  to determine the column
              length for printing selection  lists.   Automatically  set  upon
              receipt of a SIGWINCH.
       M\bMA\bAI\bIL\bL   If  this  parameter is set to a file name and the M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH vari-
              able is not set, b\bba\bas\bsh\bh informs the user of the arrival of mail in
              the specified file.
       M\bMA\bAI\bIL\bLC\bCH\bHE\bEC\bCK\bK
              Specifies  how  often  (in  seconds)  b\bba\bas\bsh\bh 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.
       M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH
              A colon-separated list of file names to  be  checked  for  mail.
              The message to be printed when mail arrives in a particular file
              may be specified by separating the file name  from  the  message
              with a `?'.  When used in the text of the message, $\b$_\b_ expands to
              the name of the current mailfile.  Example:
              M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH='/var/mail/bfox?"You  have  mail":~/shell-mail?"$_  has
              mail!"'
              B\bBa\bas\bsh\bh  supplies  a default value for this variable, but the loca-
              tion of the user mail files that it  uses  is  system  dependent
              (e.g., /var/mail/$\b$U\bUS\bSE\bER\bR).
       O\bOP\bPT\bTE\bER\bRR\bR If set to the value 1, b\bba\bas\bsh\bh displays error messages generated by
              the g\bge\bet\bto\bop\bpt\bts\bs builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  below).
              O\bOP\bPT\bTE\bER\bRR\bR  is  initialized to 1 each time the shell is invoked or a
              shell script is executed.
       P\bPA\bAT\bTH\bH   The search path for commands.  It is a colon-separated  list  of
              directories  in  which the shell looks for commands (see C\bCO\bOM\bMM\bMA\bAN\bND\bD
              E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN below).  A zero-length (null) directory  name  in  the
              value of P\bPA\bAT\bTH\bH 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 b\bba\bas\bsh\bh.  A common  value  is
              ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''.
       P\bPO\bOS\bSI\bIX\bXL\bLY\bY_\b_C\bCO\bOR\bRR\bRE\bEC\bCT\bT
              If  this  variable  is  in the environment when b\bba\bas\bsh\bh starts, the
              shell enters _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be before reading the startup files, as  if
              the  -\b--\b-p\bpo\bos\bsi\bix\bx  invocation option had been supplied.  If it is set
              while the shell is running, b\bba\bas\bsh\bh enables _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be, as  if  the
              command _\bs_\be_\bt _\b-_\bo _\bp_\bo_\bs_\bi_\bx had been executed.
       P\bPR\bRO\bOM\bMP\bPT\bT_\b_C\bCO\bOM\bMM\bMA\bAN\bND\bD
              If set, the value is executed as a command prior to issuing each
              primary prompt.
       P\bPS\bS1\b1    The value of this parameter is expanded  (see  P\bPR\bRO\bOM\bMP\bPT\bTI\bIN\bNG\bG  below)
              and  used  as  the  primary prompt string.  The default value is
              ``\\b\s\bs-\b-\\b\v\bv\\b\$\b$ ''.
       P\bPS\bS2\b2    The value of this parameter is expanded as with P\bPS\bS1\b1 and used  as
              the secondary prompt string.  The default is ``>\b> ''.
       P\bPS\bS3\b3    The value of this parameter is used as the prompt for the s\bse\bel\ble\bec\bct\bt
              command (see S\bSH\bHE\bEL\bLL\bL G\bGR\bRA\bAM\bMM\bMA\bAR\bR above).
       P\bPS\bS4\b4    The value of this parameter is expanded  as  with  P\bPS\bS1\b1  and  the
              value  is  printed  before  each command b\bba\bas\bsh\bh displays during an
              execution trace.  The first character of P\bPS\bS4\b4 is replicated  mul-
              tiple  times, as necessary, to indicate multiple levels of indi-
              rection.  The default is ``+\b+ ''.
       S\bSH\bHE\bEL\bLL\bL  The full pathname to the shell is kept in this environment vari-
              able.   If  it is not set when the shell starts, b\bba\bas\bsh\bh assigns to
              it the full pathname of the current user's login shell.
       T\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT
              The value of this parameter is used as a format string  specify-
              ing  how  the timing information for pipelines prefixed with the
              t\bti\bim\bme\be reserved word should be displayed.  The %\b% 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.
              %\b%%\b%        A literal %\b%.
              %\b%[\b[_\bp]\b][\b[l\bl]\b]R\bR  The elapsed time in seconds.
              %\b%[\b[_\bp]\b][\b[l\bl]\b]U\bU  The number of CPU seconds spent in user mode.
              %\b%[\b[_\bp]\b][\b[l\bl]\b]S\bS  The number of CPU seconds spent in system mode.
              %\b%P\bP        The CPU percentage, computed as (%U + %S) / %R.

              The  optional  _\bp is a digit specifying the _\bp_\br_\be_\bc_\bi_\bs_\bi_\bo_\bn, 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  _\bp  greater
              than  3 are changed to 3.  If _\bp is not specified, the value 3 is
              used.

              The optional l\bl specifies a longer format, including minutes,  of
              the  form  _\bM_\bMm_\bS_\bS._\bF_\bFs.   The value of _\bp determines whether or not
              the fraction is included.

              If this variable is not set, b\bba\bas\bsh\bh acts as if it  had  the  value
              $\b$'\b'\\b\n\bnr\bre\bea\bal\bl\\b\t\bt%\b%3\b3l\blR\bR\\b\n\bnu\bus\bse\ber\br\\b\t\bt%\b%3\b3l\blU\bU\\b\n\bns\bsy\bys\bs%\b%3\b3l\blS\bS'\b'.   If the value is null, no
              timing information is displayed.  A trailing  newline  is  added
              when the format string is displayed.

       T\bTM\bMO\bOU\bUT\bT  If  set  to  a  value greater than zero, T\bTM\bMO\bOU\bUT\bT is treated as the
              default timeout for the r\bre\bea\bad\bd builtin.  The s\bse\bel\ble\bec\bct\bt command termi-
              nates if input does not arrive after T\bTM\bMO\bOU\bUT\bT seconds when input is
              coming from a terminal.  In an interactive shell, the  value  is
              interpreted  as  the  number  of seconds to wait for input after
              issuing the primary prompt.  B\bBa\bas\bsh\bh terminates after  waiting  for
              that number of seconds if input does not arrive.

       a\bau\but\bto\bo_\b_r\bre\bes\bsu\bum\bme\be
              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  _\bn_\ba_\bm_\be  of  a
              stopped  job, in this context, is the command line used to start
              it.  If set to the value _\be_\bx_\ba_\bc_\bt, the string supplied  must  match
              the  name  of  a  stopped  job exactly; if set to _\bs_\bu_\bb_\bs_\bt_\br_\bi_\bn_\bg, the
              string supplied needs to match a substring  of  the  name  of  a
              stopped  job.  The _\bs_\bu_\bb_\bs_\bt_\br_\bi_\bn_\bg value provides functionality analo-
              gous to the %\b%?\b?  job identifier (see J\bJO\bOB\bB C\bCO\bON\bNT\bTR\bRO\bOL\bL 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
              %\b% job identifier.

       h\bhi\bis\bst\btc\bch\bha\bar\brs\bs
              The  two or three characters which control history expansion and
              tokenization (see H\bHI\bIS\bST\bTO\bOR\bRY\bY E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below).  The first character
              is  the _\bh_\bi_\bs_\bt_\bo_\br_\by _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn character, the character which signals
              the start of a history  expansion,  normally  `!\b!'.   The  second
              character  is the _\bq_\bu_\bi_\bc_\bk _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn 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
              `^\b^'.  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 `#\b#'.  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.

   A\bAr\brr\bra\bay\bys\bs
       B\bBa\bas\bsh\bh  provides  one-dimensional  array  variables.  Any variable may be
       used as an array; the d\bde\bec\bcl\bla\bar\bre\be 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 contiguously.  Arrays  are  indexed
       using integers and are zero-based.

       An  array is created automatically if any variable is assigned to using
       the syntax _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]=_\bv_\ba_\bl_\bu_\be.   The  _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt  is  treated  as  an
       arithmetic  expression  that  must evaluate to a number greater than or
       equal to zero.  To explicitly declare an array,  use  d\bde\bec\bcl\bla\bar\bre\be  -\b-a\ba  _\bn_\ba_\bm_\be
       (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).  d\bde\bec\bcl\bla\bar\bre\be -\b-a\ba _\bn_\ba_\bm_\be[\b[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]\b] is also
       accepted; the _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is ignored.  Attributes may be specified for an
       array variable using the d\bde\bec\bcl\bla\bar\bre\be and r\bre\bea\bad\bdo\bon\bnl\bly\by builtins.  Each attribute
       applies to all members of an array.

       Arrays  are  assigned  to  using  compound  assignments  of  the   form
       _\bn_\ba_\bm_\be=(\b(value_\b1  ...  value_\bn)\b),  where  each  _\bv_\ba_\bl_\bu_\be  is  of  the form [_\bs_\bu_\bb_\b-
       _\bs_\bc_\br_\bi_\bp_\bt]=_\bs_\bt_\br_\bi_\bn_\bg.  Only _\bs_\bt_\br_\bi_\bn_\bg is required.  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.  This syntax is also accepted by
       the d\bde\bec\bcl\bla\bar\bre\be builtin.  Individual array  elements  may  be  assigned  to
       using the _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]=_\bv_\ba_\bl_\bu_\be syntax introduced above.

       Any  element  of  an  array may be referenced using ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}.
       The braces are required to avoid conflicts with pathname expansion.  If
       _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt  is  @\b@  or *\b*, the word expands to all members of _\bn_\ba_\bm_\be.  These
       subscripts differ only when the word appears within double quotes.   If
       the word is double-quoted, ${_\bn_\ba_\bm_\be[*]} expands to a single word with the
       value of each array member separated by the first character of the  I\bIF\bFS\bS
       special variable, and ${_\bn_\ba_\bm_\be[@]} expands each element of _\bn_\ba_\bm_\be to a sep-
       arate word.  When there are no array  members,  ${_\bn_\ba_\bm_\be[@]}  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 *\b* and @\b@ (see S\bSp\bpe\bec\bci\bia\bal\bl P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs
       above).  ${#_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}  expands  to  the  length  of  ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\b-
       _\bs_\bc_\br_\bi_\bp_\bt]}.   If _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is *\b* or @\b@, the expansion is the number of ele-
       ments in the array.  Referencing an array variable without a  subscript
       is equivalent to referencing element zero.

       The  u\bun\bns\bse\bet\bt  builtin  is  used to destroy arrays.  u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]
       destroys the array element at index _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt.  u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be, where  _\bn_\ba_\bm_\be
       is  an  array,  or  u\bun\bns\bse\bet\bt  _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt],  where _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is *\b* or @\b@,
       removes the entire array.

       The d\bde\bec\bcl\bla\bar\bre\be, l\blo\boc\bca\bal\bl, and r\bre\bea\bad\bdo\bon\bnl\bly\by builtins each accept a  -\b-a\ba  option  to
       specify  an  array.   The  r\bre\bea\bad\bd builtin accepts a -\b-a\ba option to assign a
       list of words read from the standard input to an array.   The  s\bse\bet\bt  and
       d\bde\bec\bcl\bla\bar\bre\be  builtins  display array values in a way that allows them to be
       reused as assignments.

E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
       Expansion is performed on the command line after it has been split into
       words.   There are seven kinds of expansion performed: _\bb_\br_\ba_\bc_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn,
       _\bt_\bi_\bl_\bd_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br _\ba_\bn_\bd _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be  _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn,  _\bc_\bo_\bm_\bm_\ba_\bn_\bd  _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\b-
       _\bt_\bi_\bo_\bn, _\ba_\br_\bi_\bt_\bh_\bm_\be_\bt_\bi_\bc _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bw_\bo_\br_\bd _\bs_\bp_\bl_\bi_\bt_\bt_\bi_\bn_\bg, and _\bp_\ba_\bt_\bh_\bn_\ba_\bm_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn.

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

       On systems that can support it, there is an additional expansion avail-
       able: _\bp_\br_\bo_\bc_\be_\bs_\bs _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn.

       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 "$\b$@\b@" and "$\b${\b{_\bn_\ba_\bm_\be[\b[@\b@]\b]}\b}" as explained above (see P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS).

   B\bBr\bra\bac\bce\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
       _\bB_\br_\ba_\bc_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn is a mechanism by which arbitrary strings may be gener-
       ated.  This mechanism is similar to _\bp_\ba_\bt_\bh_\bn_\ba_\bm_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, but  the  file-
       names generated need not exist.  Patterns to be brace expanded take the
       form of an optional _\bp_\br_\be_\ba_\bm_\bb_\bl_\be, followed by either a series of comma-sep-
       arated  strings or a sequence expression between a pair of braces, fol-
       lowed by an optional _\bp_\bo_\bs_\bt_\bs_\bc_\br_\bi_\bp_\bt.  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{\b{d,c,b}\b}e expands into `ade ace abe'.

       A sequence expression takes the form {\b{_\bx.\b..\b._\by}\b}, where _\bx and _\by  are  either
       integers or single characters.  When integers are supplied, the expres-
       sion expands to each number between _\bx and _\by, inclusive.   When  charac-
       ters  are  supplied,  the  expression expands to each character lexico-
       graphically between _\bx and _\by, inclusive.  Note that both _\bx and _\by must be
       of the same type.

       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.  B\bBa\bas\bsh\bh 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 {\b{ or ,\b, 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 $\b${\b{ 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 s\bsh\bh.  s\bsh\bh does not treat opening or closing braces specially
       when they appear as part of a word, and preserves them in  the  output.
       B\bBa\bas\bsh\bh  removes  braces  from  words as a consequence of brace expansion.
       For example, a word entered to s\bsh\bh as _\bf_\bi_\bl_\be_\b{_\b1_\b,_\b2_\b} appears  identically  in
       the  output.  The same word is output as _\bf_\bi_\bl_\be_\b1 _\bf_\bi_\bl_\be_\b2 after expansion by
       b\bba\bas\bsh\bh.  If strict compatibility with s\bsh\bh is desired, start b\bba\bas\bsh\bh with  the
       +\b+B\bB option or disable brace expansion with the +\b+B\bB option to the s\bse\bet\bt com-
       mand (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

   T\bTi\bil\bld\bde\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
       If a word begins with an unquoted tilde character  (`~\b~'),  all  of  the
       characters  preceding  the  first unquoted slash (or all characters, if
       there is no unquoted slash) are considered a _\bt_\bi_\bl_\bd_\be_\b-_\bp_\br_\be_\bf_\bi_\bx.  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 _\bl_\bo_\bg_\bi_\bn  _\bn_\ba_\bm_\be.
       If  this  login name is the null string, the tilde is replaced with the
       value of the shell parameter H\bHO\bOM\bME\bE.  If H\bHO\bOM\bME\bE 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 P\bPW\bWD\bD
       replaces the tilde-prefix.  If the tilde-prefix is a `~-', the value of
       the  shell variable O\bOL\bLD\bDP\bPW\bWD\bD, if it is set, is substituted.  If the char-
       acters following the tilde in the tilde-prefix consist of a  number  _\bN,
       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 d\bdi\bir\brs\bs 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 :\b: or =\b=.  In these cases, tilde expansion is also per-
       formed.  Consequently, one may use file names with  tildes  in  assign-
       ments to P\bPA\bAT\bTH\bH, M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH, and C\bCD\bDP\bPA\bAT\bTH\bH, and the shell assigns the expanded
       value.

   P\bPa\bar\bra\bam\bme\bet\bte\ber\br E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
       The `$\b$' 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  `}\b}'  not
       escaped  by  a  backslash  or within a quoted string, and not within an
       embedded arithmetic expansion, command substitution, or paramter expan-
       sion.

       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br}
              The  value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is substituted.  The braces are required
              when _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a positional  parameter  with  more  than  one
              digit, or when _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is followed by a character which is not
              to be interpreted as part of its name.

       If the first character of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an exclamation point, a level of
       variable  indirection  is introduced.  B\bBa\bas\bsh\bh uses the value of the vari-
       able formed from the rest of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br 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 _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br itself.   This  is
       known as _\bi_\bn_\bd_\bi_\br_\be_\bc_\bt _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn.  The exceptions to this are the expansions
       of ${!_\bp_\br_\be_\bf_\bi_\bx*} and ${!\b!_\bn_\ba_\bm_\be[_\b@]} described below.  The exclamation  point
       must  immediately  follow the left brace in order to introduce indirec-
       tion.

       In each of the cases below, _\bw_\bo_\br_\bd is subject to tilde expansion, parame-
       ter  expansion,  command  substitution, and arithmetic expansion.  When
       not performing substring expansion, b\bba\bas\bsh\bh tests for a parameter that  is
       unset  or null; omitting the colon results in a test only for a parame-
       ter that is unset.

       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:-\b-_\bw_\bo_\br_\bd}
              U\bUs\bse\be D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is unset or null,  the  expan-
              sion  of _\bw_\bo_\br_\bd is substituted.  Otherwise, the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br
              is substituted.
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:=\b=_\bw_\bo_\br_\bd}
              A\bAs\bss\bsi\big\bgn\bn D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs.  If  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  is  unset  or  null,  the
              expansion of _\bw_\bo_\br_\bd is assigned to _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.  The value of _\bp_\ba_\br_\ba_\bm_\b-
              _\be_\bt_\be_\br is then substituted.   Positional  parameters  and  special
              parameters may not be assigned to in this way.
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:?\b?_\bw_\bo_\br_\bd}
              D\bDi\bis\bsp\bpl\bla\bay\by  E\bEr\brr\bro\bor\br i\bif\bf N\bNu\bul\bll\bl o\bor\br U\bUn\bns\bse\bet\bt.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset,
              the expansion of _\bw_\bo_\br_\bd (or a message to that effect  if  _\bw_\bo_\br_\bd  is
              not  present) is written to the standard error and the shell, if
              it is not interactive, exits.  Otherwise, the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br
              is substituted.
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:+\b+_\bw_\bo_\br_\bd}
              U\bUs\bse\be  A\bAl\blt\bte\ber\brn\bna\bat\bte\be V\bVa\bal\blu\bue\be.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset, nothing is
              substituted, otherwise the expansion of _\bw_\bo_\br_\bd is substituted.
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:_\bo_\bf_\bf_\bs_\be_\bt}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:_\bo_\bf_\bf_\bs_\be_\bt:\b:_\bl_\be_\bn_\bg_\bt_\bh}
              S\bSu\bub\bbs\bst\btr\bri\bin\bng\bg E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn.\b.  Expands to  up  to  _\bl_\be_\bn_\bg_\bt_\bh  characters  of
              _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  starting  at  the  character specified by _\bo_\bf_\bf_\bs_\be_\bt.  If
              _\bl_\be_\bn_\bg_\bt_\bh is omitted, expands to the substring of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  start-
              ing at the character specified by _\bo_\bf_\bf_\bs_\be_\bt.  _\bl_\be_\bn_\bg_\bt_\bh and _\bo_\bf_\bf_\bs_\be_\bt are
              arithmetic  expressions  (see  A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC   E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN   below).
              _\bl_\be_\bn_\bg_\bt_\bh  must evaluate to a number greater than or equal to zero.
              If _\bo_\bf_\bf_\bs_\be_\bt evaluates to a number less than  zero,  the  value  is
              used  as  an  offset from the end of the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.  If
              _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@,  the  result  is  _\bl_\be_\bn_\bg_\bt_\bh  positional  parameters
              beginning at _\bo_\bf_\bf_\bs_\be_\bt.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an array name indexed by @
              or *, the result is the _\bl_\be_\bn_\bg_\bt_\bh members of  the  array  beginning
              with  ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br[_\bo_\bf_\bf_\bs_\be_\bt]}.   Substring  indexing  is zero-based
              unless the positional parameters are used,  in  which  case  the
              indexing starts at 1.

       ${!\b!_\bp_\br_\be_\bf_\bi_\bx*\b*}
       ${!\b!_\bp_\br_\be_\bf_\bi_\bx@\b@}
              Expands to the names of variables whose names begin with _\bp_\br_\be_\bf_\bi_\bx,
              separated by the first character of the I\bIF\bFS\bS special variable.

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

       ${#\b#_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br}
              The length in characters of the value of  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  is  substi-
              tuted.   If  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  is  *\b* or @\b@, the value substituted is the
              number of positional parameters.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an array  name
              subscripted  by  *\b*  or @\b@, the value substituted is the number of
              elements in the array.

       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br#\b#_\bw_\bo_\br_\bd}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br#\b##\b#_\bw_\bo_\br_\bd}
              The _\bw_\bo_\br_\bd is expanded to produce a pattern just  as  in  pathname
              expansion.  If the pattern matches the beginning of the value of
              _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br, then the result of  the  expansion  is  the  expanded
              value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br with the shortest matching pattern (the ``#\b#''
              case) or the longest matching pattern (the ``#\b##\b#'' case) deleted.
              If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@ or *\b*, the pattern removal operation is applied
              to each positional parameter in turn, and the expansion  is  the
              resultant  list.   If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an array variable subscripted
              with @\b@ or *\b*, the pattern removal operation is  applied  to  each
              member  of the array in turn, and the expansion is the resultant
              list.

       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br%\b%_\bw_\bo_\br_\bd}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br%\b%%\b%_\bw_\bo_\br_\bd}
              The _\bw_\bo_\br_\bd is expanded to produce a pattern just  as  in  pathname
              expansion.   If  the  pattern  matches a trailing portion of the
              expanded value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br, then the result of the expansion is
              the  expanded value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br with the shortest matching pat-
              tern (the ``%\b%'' case)  or  the  longest  matching  pattern  (the
              ``%\b%%\b%''  case)  deleted.   If  _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br  is  @\b@ or *\b*, the pattern
              removal operation is applied to  each  positional  parameter  in
              turn,  and the expansion is the resultant list.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is
              an array variable subscripted with @\b@ or *\b*, the  pattern  removal
              operation  is  applied  to each member of the array in turn, and
              the expansion is the resultant list.

       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br/\b/_\bp_\ba_\bt_\bt_\be_\br_\bn/\b/_\bs_\bt_\br_\bi_\bn_\bg}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br/\b//\b/_\bp_\ba_\bt_\bt_\be_\br_\bn/\b/_\bs_\bt_\br_\bi_\bn_\bg}
              The _\bp_\ba_\bt_\bt_\be_\br_\bn is expanded to produce a pattern just as in pathname
              expansion.   _\bP_\ba_\br_\ba_\bm_\be_\bt_\be_\br is expanded and the longest match of _\bp_\ba_\bt_\b-
              _\bt_\be_\br_\bn against its value is replaced with _\bs_\bt_\br_\bi_\bn_\bg.   In  the  first
              form,  only the first match is replaced.  The second form causes
              all matches of _\bp_\ba_\bt_\bt_\be_\br_\bn to be replaced with _\bs_\bt_\br_\bi_\bn_\bg.   If  _\bp_\ba_\bt_\bt_\be_\br_\bn
              begins  with  #\b#,  it must match at the beginning of the expanded
              value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.  If _\bp_\ba_\bt_\bt_\be_\br_\bn begins with %\b%, it must match  at
              the  end of the expanded value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.  If _\bs_\bt_\br_\bi_\bn_\bg is null,
              matches of _\bp_\ba_\bt_\bt_\be_\br_\bn are deleted and the /\b/ following  _\bp_\ba_\bt_\bt_\be_\br_\bn  may
              be  omitted.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@ or *\b*, the substitution operation
              is applied to each positional parameter in turn, and the  expan-
              sion  is  the resultant list.  If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an array variable
              subscripted with @\b@ or *\b*, the substitution operation  is  applied
              to  each  member  of the array in turn, and the expansion is the
              resultant list.

   C\bCo\bom\bmm\bma\ban\bnd\bd S\bSu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
       _\bC_\bo_\bm_\bm_\ba_\bn_\bd _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn allows the output of a command to replace the com-
       mand name.  There are two forms:


              $\b$(\b(_\bc_\bo_\bm_\bm_\ba_\bn_\bd)\b)
       or
              `\b`_\bc_\bo_\bm_\bm_\ba_\bn_\bd`\b`

       B\bBa\bas\bsh\bh performs the expansion by executing _\bc_\bo_\bm_\bm_\ba_\bn_\bd 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  $\b$(\b(c\bca\bat\bt
       _\bf_\bi_\bl_\be)\b) can be replaced by the equivalent but faster $\b$(\b(<\b< _\bf_\bi_\bl_\be)\b).

       When  the  old-style  backquote form of substitution is used, backslash
       retains its literal meaning except when followed by $\b$, `\b`,  or  \\b\.   The
       first backquote not preceded by a backslash terminates the command sub-
       stitution.  When using the $(_\bc_\bo_\bm_\bm_\ba_\bn_\bd) 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.

   A\bAr\bri\bit\bth\bhm\bme\bet\bti\bic\bc E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
       Arithmetic  expansion allows the evaluation of an arithmetic expression
       and the substitution of the result.  The format for  arithmetic  expan-
       sion is:

              $\b$(\b((\b(_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn)\b))\b)

       The  _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn  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 expansion, string expansion,
       command substitution, and quote removal.  Arithmetic expansions may  be
       nested.

       The  evaluation  is performed according to the rules listed below under
       A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN.  If _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn is invalid, b\bba\bas\bsh\bh prints a message
       indicating failure and no substitution occurs.

   P\bPr\bro\boc\bce\bes\bss\bs S\bSu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
       _\bP_\br_\bo_\bc_\be_\bs_\bs  _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn  is supported on systems that support named pipes
       (_\bF_\bI_\bF_\bO_\bs) or the /\b/d\bde\bev\bv/\b/f\bfd\bd method of naming open files.  It takes the  form
       of  <\b<(\b(_\bl_\bi_\bs_\bt)\b) or >\b>(\b(_\bl_\bi_\bs_\bt)\b).  The process _\bl_\bi_\bs_\bt is run with its input or out-
       put connected to a _\bF_\bI_\bF_\bO or some file in /\b/d\bde\bev\bv/\b/f\bfd\bd.  The name of this file
       is  passed  as  an argument to the current command as the result of the
       expansion.  If the >\b>(\b(_\bl_\bi_\bs_\bt)\b) form is used, writing to the file will  pro-
       vide  input  for _\bl_\bi_\bs_\bt.  If the <\b<(\b(_\bl_\bi_\bs_\bt)\b) form is used, the file passed as
       an argument should be read to obtain the output of _\bl_\bi_\bs_\bt.

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

   W\bWo\bor\brd\bd S\bSp\bpl\bli\bit\btt\bti\bin\bng\bg
       The shell scans the results of parameter expansion,  command  substitu-
       tion,  and arithmetic expansion that did not occur within double quotes
       for _\bw_\bo_\br_\bd _\bs_\bp_\bl_\bi_\bt_\bt_\bi_\bn_\bg.

       The shell treats each character of I\bIF\bFS\bS as a delimiter, and  splits  the
       results of the other expansions into words on these characters.  If I\bIF\bFS\bS
       is unset, or its value is exactly <\b<s\bsp\bpa\bac\bce\be>\b><\b<t\bta\bab\bb>\b><\b<n\bne\bew\bwl\bli\bin\bne\be>\b>,  the  default,
       then  any  sequence  of I\bIF\bFS\bS characters serves to delimit words.  If I\bIF\bFS\bS
       has a value other than the default, then sequences  of  the  whitespace
       characters  s\bsp\bpa\bac\bce\be  and  t\bta\bab\bb are ignored at the beginning and end of the
       word, as long as the whitespace character is in the value  of  I\bIF\bFS\bS  (an
       I\bIF\bFS\bS  whitespace  character).   Any  character  in  I\bIF\bFS\bS  that is not I\bIF\bFS\bS
       whitespace, along with any adjacent I\bIF\bFS\bS whitespace characters, delimits
       a  field.  A sequence of I\bIF\bFS\bS whitespace characters is also treated as a
       delimiter.  If the value of I\bIF\bFS\bS is null, no word splitting occurs.

       Explicit null arguments ("\b""\b" or '\b''\b')  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.

   P\bPa\bat\bth\bhn\bna\bam\bme\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
       After  word  splitting,  unless  the -\b-f\bf option has been set, b\bba\bas\bsh\bh scans
       each word for the characters *\b*, ?\b?, and [\b[.  If one of  these  characters
       appears,  then  the word is regarded as a _\bp_\ba_\bt_\bt_\be_\br_\bn, and replaced with an
       alphabetically sorted list of file names matching the pattern.   If  no
       matching  file  names  are found, and the shell option n\bnu\bul\bll\blg\bgl\blo\bob\bb is dis-
       abled, the word is left unchanged.  If the n\bnu\bul\bll\blg\bgl\blo\bob\bb option is set,  and
       no  matches  are  found,  the  word  is removed.  If the f\bfa\bai\bil\blg\bgl\blo\bob\bb shell
       option is set, and no matches are found, an error  message  is  printed
       and  the  command  is  not executed.  If the shell option n\bno\boc\bca\bas\bse\beg\bgl\blo\bob\bb is
       enabled, the match is performed without regard to the  case  of  alpha-
       betic  characters.   When a pattern is used for pathname expansion, the
       character `\b``\b`.\b.'\b''\b'  at the start of a  name  or  immediately  following  a
       slash  must  be  matched explicitly, unless the shell option d\bdo\bot\btg\bgl\blo\bob\bb is
       set.  When matching a pathname, the  slash  character  must  always  be
       matched  explicitly.   In  other  cases,  the  `\b``\b`.\b.'\b''\b'   character is not
       treated specially.  See the description  of  s\bsh\bho\bop\bpt\bt  below  under  S\bSH\bHE\bEL\bLL\bL
       B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  for a description of the n\bno\boc\bca\bas\bse\beg\bgl\blo\bob\bb, n\bnu\bul\bll\blg\bgl\blo\bob\bb, f\bfa\bai\bil\bl-\b-
       g\bgl\blo\bob\bb, and d\bdo\bot\btg\bgl\blo\bob\bb shell options.

       The G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE shell variable may be used to restrict the set  of  file
       names  matching  a  _\bp_\ba_\bt_\bt_\be_\br_\bn.   If G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE is set, each matching file
       name that also matches one of the patterns  in  G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE  is  removed
       from the list of matches.  The file names `\b``\b`.\b.'\b''\b'  and `\b``\b`.\b..\b.'\b''\b'  are always
       ignored when G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE is set and not null.  However, setting  G\bGL\bLO\bOB\bBI\bIG\bG-\b-
       N\bNO\bOR\bRE\bE  to  a non-null value has the effect of enabling the d\bdo\bot\btg\bgl\blo\bob\bb shell
       option, so all other file names beginning with a `\b``\b`.\b.'\b''\b'  will match.  To
       get  the  old  behavior  of ignoring file names beginning with a `\b``\b`.\b.'\b''\b',
       make `\b``\b`.\b.*\b*'\b''\b'  one of the patterns in G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE.  The d\bdo\bot\btg\bgl\blo\bob\bb option  is
       disabled when G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE is unset.

       P\bPa\bat\btt\bte\ber\brn\bn M\bMa\bat\btc\bch\bhi\bin\bng\bg

       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:

       *\b*      Matches any string, including the null string.
       ?\b?      Matches any single character.
       [\b[.\b..\b..\b.]\b]  Matches  any  one of the enclosed characters.  A pair of charac-
              ters separated by a hyphen denotes a _\br_\ba_\bn_\bg_\be _\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn; any char-
              acter  that sorts between those two characters, inclusive, using
              the current locale's collating sequence and  character  set,  is
              matched.   If the first character following the [\b[ is a !\b!  or a ^\b^
              then any character not enclosed is matched.  The  sorting  order
              of  characters in range expressions is determined by the current
              locale and the value of the L\bLC\bC_\b_C\bCO\bOL\bLL\bLA\bAT\bTE\bE shell variable,  if  set.
              A  -\b- may be matched by including it as the first or last charac-
              ter in the set.  A ]\b] may be matched by including it as the first
              character in the set.

              Within  [\b[  and  ]\b],  _\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br _\bc_\bl_\ba_\bs_\bs_\be_\bs can be specified using the
              syntax [\b[:\b:_\bc_\bl_\ba_\bs_\bs:\b:]\b], where _\bc_\bl_\ba_\bs_\bs is one of  the  following  classes
              defined in the POSIX.2 standard:
              a\bal\bln\bnu\bum\bm  a\bal\blp\bph\bha\ba  a\bas\bsc\bci\bii\bi  b\bbl\bla\ban\bnk\bk  c\bcn\bnt\btr\brl\bl  d\bdi\big\bgi\bit\bt g\bgr\bra\bap\bph\bh l\blo\bow\bwe\ber\br p\bpr\bri\bin\bnt\bt p\bpu\bun\bnc\bct\bt
              s\bsp\bpa\bac\bce\be u\bup\bpp\bpe\ber\br w\bwo\bor\brd\bd x\bxd\bdi\big\bgi\bit\bt
              A character class matches any character belonging to that class.
              The  w\bwo\bor\brd\bd character class matches letters, digits, and the char-
              acter _.

              Within [\b[ and ]\b], an _\be_\bq_\bu_\bi_\bv_\ba_\bl_\be_\bn_\bc_\be _\bc_\bl_\ba_\bs_\bs can be specified using  the
              syntax  [\b[=\b=_\bc=\b=]\b], which matches all characters with the same colla-
              tion weight (as defined by the current locale) as the  character
              _\bc.

              Within [\b[ and ]\b], the syntax [\b[.\b._\bs_\by_\bm_\bb_\bo_\bl.\b.]\b] matches the collating sym-
              bol _\bs_\by_\bm_\bb_\bo_\bl.

       If the e\bex\bxt\btg\bgl\blo\bob\bb shell option is enabled using the s\bsh\bho\bop\bpt\bt builtin, several
       extended  pattern  matching operators are recognized.  In the following
       description, a _\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt is a list of one or more patterns separated
       by a |\b|.  Composite patterns may be formed using one or more of the fol-
       lowing sub-patterns:

              ?\b?(\b(_\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt)\b)
                     Matches zero or one occurrence of the given patterns
              *\b*(\b(_\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt)\b)
                     Matches zero or more occurrences of the given patterns
              +\b+(\b(_\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt)\b)
                     Matches one or more occurrences of the given patterns
              @\b@(\b(_\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt)\b)
                     Matches exactly one of the given patterns
              !\b!(\b(_\bp_\ba_\bt_\bt_\be_\br_\bn_\b-_\bl_\bi_\bs_\bt)\b)
                     Matches anything except one of the given patterns

   Q\bQu\buo\bot\bte\be R\bRe\bem\bmo\bov\bva\bal\bl
       After the preceding expansions, all unquoted occurrences of the charac-
       ters  \\b\,  '\b', and "\b" that did not result from one of the above expansions
       are removed.

R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN
       Before a command is executed, its input and output  may  be  _\br_\be_\bd_\bi_\br_\be_\bc_\bt_\be_\bd
       using  a  special  notation  interpreted by the shell.  Redirection may
       also be used to open and close files for the  current  shell  execution
       environment.  The following redirection operators may precede or appear
       anywhere within a _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd or may follow a _\bc_\bo_\bm_\bm_\ba_\bn_\bd.  Redirections
       are processed in the order they appear, from left to right.

       In  the  following descriptions, if the file descriptor number is omit-
       ted, and the first character of the  redirection  operator  is  <\b<,  the
       redirection  refers  to the standard input (file descriptor 0).  If the
       first character of the  redirection  operator  is  >\b>,  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 expansion, command substitution, arithmetic expan-
       sion, quote removal, pathname expansion, and  word  splitting.   If  it
       expands to more than one word, b\bba\bas\bsh\bh reports an error.

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

              ls >\b> dirlist 2>\b>&\b&1

       directs both standard output and standard error to  the  file  _\bd_\bi_\br_\bl_\bi_\bs_\bt,
       while the command

              ls 2>\b>&\b&1 >\b> dirlist

       directs  only the standard output to file _\bd_\bi_\br_\bl_\bi_\bs_\bt, because the standard
       error was duplicated as standard output before the standard output  was
       redirected to _\bd_\bi_\br_\bl_\bi_\bs_\bt.

       B\bBa\bas\bsh\bh handles several filenames specially when they are used in redirec-
       tions, as described in the following table:

              /\b/d\bde\bev\bv/\b/f\bfd\bd/\b/_\bf_\bd
                     If _\bf_\bd is a valid integer, file descriptor  _\bf_\bd  is  dupli-
                     cated.
              /\b/d\bde\bev\bv/\b/s\bst\btd\bdi\bin\bn
                     File descriptor 0 is duplicated.
              /\b/d\bde\bev\bv/\b/s\bst\btd\bdo\bou\but\bt
                     File descriptor 1 is duplicated.
              /\b/d\bde\bev\bv/\b/s\bst\btd\bde\ber\brr\br
                     File descriptor 2 is duplicated.
              /\b/d\bde\bev\bv/\b/t\btc\bcp\bp/\b/_\bh_\bo_\bs_\bt/\b/_\bp_\bo_\br_\bt
                     If _\bh_\bo_\bs_\bt is a valid hostname or Internet address, and _\bp_\bo_\br_\bt
                     is an integer port number or service name, b\bba\bas\bsh\bh  attempts
                     to open a TCP connection to the corresponding socket.
              /\b/d\bde\bev\bv/\b/u\bud\bdp\bp/\b/_\bh_\bo_\bs_\bt/\b/_\bp_\bo_\br_\bt
                     If _\bh_\bo_\bs_\bt is a valid hostname or Internet address, and _\bp_\bo_\br_\bt
                     is an integer port number or service name, b\bba\bas\bsh\bh  attempts
                     to open a UDP connection to the corresponding socket.

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

   R\bRe\bed\bdi\bir\bre\bec\bct\bti\bin\bng\bg I\bIn\bnp\bpu\but\bt
       Redirection of input causes the file whose name results from the expan-
       sion of _\bw_\bo_\br_\bd to be opened for reading on  file  descriptor  _\bn,  or  the
       standard input (file descriptor 0) if _\bn is not specified.

       The general format for redirecting input is:

              [_\bn]<\b<_\bw_\bo_\br_\bd

   R\bRe\bed\bdi\bir\bre\bec\bct\bti\bin\bng\bg O\bOu\but\btp\bpu\but\bt
       Redirection  of  output  causes  the  file  whose name results from the
       expansion of _\bw_\bo_\br_\bd to be opened for writing on file descriptor _\bn, or the
       standard output (file descriptor 1) if _\bn 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:

              [_\bn]>\b>_\bw_\bo_\br_\bd

       If  the  redirection operator is >\b>, and the n\bno\boc\bcl\blo\bob\bbb\bbe\ber\br option to the s\bse\bet\bt
       builtin has been enabled, the redirection will fail if the  file  whose
       name  results  from the expansion of _\bw_\bo_\br_\bd exists and is a regular file.
       If the redirection operator is >\b>|\b|, or the redirection operator is >\b> and
       the  n\bno\boc\bcl\blo\bob\bbb\bbe\ber\br  option  to  the s\bse\bet\bt builtin command is not enabled, the
       redirection is attempted even if the file named by _\bw_\bo_\br_\bd exists.

   A\bAp\bpp\bpe\ben\bnd\bdi\bin\bng\bg R\bRe\bed\bdi\bir\bre\bec\bct\bte\bed\bd O\bOu\but\btp\bpu\but\bt
       Redirection of output in  this  fashion  causes  the  file  whose  name
       results  from  the expansion of _\bw_\bo_\br_\bd to be opened for appending on file
       descriptor _\bn, or the standard output (file descriptor 1) if  _\bn  is  not
       specified.  If the file does not exist it is created.

       The general format for appending output is:

              [_\bn]>\b>>\b>_\bw_\bo_\br_\bd


   R\bRe\bed\bdi\bir\bre\bec\bct\bti\bin\bng\bg S\bSt\bta\ban\bnd\bda\bar\brd\bd O\bOu\but\btp\bpu\but\bt a\ban\bnd\bd S\bSt\bta\ban\bnd\bda\bar\brd\bd E\bEr\brr\bro\bor\br
       B\bBa\bas\bsh\bh  allows both the standard output (file descriptor 1) and the stan-
       dard error output (file descriptor 2) to  be  redirected  to  the  file
       whose name is the expansion of _\bw_\bo_\br_\bd with this construct.

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

              &\b&>\b>_\bw_\bo_\br_\bd
       and
              >\b>&\b&_\bw_\bo_\br_\bd

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

              >\b>_\bw_\bo_\br_\bd 2>\b>&\b&1

   H\bHe\ber\bre\be D\bDo\boc\bcu\bum\bme\ben\bnt\bts\bs
       This  type  of  redirection  instructs the shell to read input from the
       current source until a line containing  only  _\bw_\bo_\br_\bd  (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:

              <\b<<\b<[-\b-]_\bw_\bo_\br_\bd
                      _\bh_\be_\br_\be_\b-_\bd_\bo_\bc_\bu_\bm_\be_\bn_\bt
              _\bd_\be_\bl_\bi_\bm_\bi_\bt_\be_\br

       No parameter expansion, command substitution, arithmetic expansion,  or
       pathname expansion is performed on _\bw_\bo_\br_\bd.  If any characters in _\bw_\bo_\br_\bd are
       quoted, the _\bd_\be_\bl_\bi_\bm_\bi_\bt_\be_\br is the result of quote removal on _\bw_\bo_\br_\bd,  and  the
       lines  in the here-document are not expanded.  If _\bw_\bo_\br_\bd is unquoted, all
       lines of the here-document are subjected to parameter  expansion,  com-
       mand  substitution,  and arithmetic expansion.  In the latter case, the
       character sequence \\b\<\b<n\bne\bew\bwl\bli\bin\bne\be>\b> is ignored, and \\b\ must be used  to  quote
       the characters \\b\, $\b$, and `\b`.

       If the redirection operator is <\b<<\b<-\b-, then all leading tab characters are
       stripped from input lines and  the  line  containing  _\bd_\be_\bl_\bi_\bm_\bi_\bt_\be_\br.   This
       allows  here-documents within shell scripts to be indented in a natural
       fashion.

   H\bHe\ber\bre\be S\bSt\btr\bri\bin\bng\bgs\bs
       A variant of here documents, the format is:

              <\b<<\b<<\b<_\bw_\bo_\br_\bd

       The _\bw_\bo_\br_\bd is expanded and supplied to the command on its standard input.

   D\bDu\bup\bpl\bli\bic\bca\bat\bti\bin\bng\bg F\bFi\bil\ble\be D\bDe\bes\bsc\bcr\bri\bip\bpt\bto\bor\brs\bs
       The redirection operator

              [_\bn]<\b<&\b&_\bw_\bo_\br_\bd

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

       The operator

              [_\bn]>\b>&\b&_\bw_\bo_\br_\bd

       is used similarly to duplicate output file descriptors.  If  _\bn  is  not
       specified,  the  standard  output  (file descriptor 1) is used.  If the
       digits in _\bw_\bo_\br_\bd do not specify a file  descriptor  open  for  output,  a
       redirection error occurs.  As a special case, if _\bn is omitted, and _\bw_\bo_\br_\bd
       does not expand to one or more digits, the standard output and standard
       error are redirected as described previously.

   M\bMo\bov\bvi\bin\bng\bg F\bFi\bil\ble\be D\bDe\bes\bsc\bcr\bri\bip\bpt\bto\bor\brs\bs
       The redirection operator

              [_\bn]<\b<&\b&_\bd_\bi_\bg_\bi_\bt-\b-

       moves  the  file descriptor _\bd_\bi_\bg_\bi_\bt to file descriptor _\bn, or the standard
       input (file descriptor 0) if _\bn is not specified.  _\bd_\bi_\bg_\bi_\bt is closed after
       being duplicated to _\bn.

       Similarly, the redirection operator

              [_\bn]>\b>&\b&_\bd_\bi_\bg_\bi_\bt-\b-

       moves  the  file descriptor _\bd_\bi_\bg_\bi_\bt to file descriptor _\bn, or the standard
       output (file descriptor 1) if _\bn is not specified.

   O\bOp\bpe\ben\bni\bin\bng\bg F\bFi\bil\ble\be D\bDe\bes\bsc\bcr\bri\bip\bpt\bto\bor\brs\bs f\bfo\bor\br R\bRe\bea\bad\bdi\bin\bng\bg a\ban\bnd\bd W\bWr\bri\bit\bti\bin\bng\bg
       The redirection operator

              [_\bn]<\b<>\b>_\bw_\bo_\br_\bd

       causes the file whose name is the expansion of _\bw_\bo_\br_\bd to  be  opened  for
       both  reading and writing on file descriptor _\bn, or on file descriptor 0
       if _\bn is not specified.  If the file does not exist, it is created.

A\bAL\bLI\bIA\bAS\bSE\bES\bS
       _\bA_\bl_\bi_\ba_\bs_\be_\bs 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 a\bal\bli\bia\bas\bs  and  u\bun\bna\bal\bli\bia\bas\bs  builtin
       commands  (see  S\bSH\bHE\bEL\bLL\bL  B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS 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 /\b/,
       $\b$, `\b`, and =\b= and any of the shell _\bm_\be_\bt_\ba_\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br_\bs 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 l\bls\bs to l\bls\bs -\b-F\bF, for instance, and
       b\bba\bas\bsh\bh does not try to recursively expand the replacement text.   If  the
       last  character  of  the  alias value is a _\bb_\bl_\ba_\bn_\bk, then the next command
       word following the alias is also checked for alias expansion.

       Aliases are created and listed with the a\bal\bli\bia\bas\bs command, and removed with
       the u\bun\bna\bal\bli\bia\bas\bs command.

       There  is no mechanism for using arguments in the replacement text.  If
       arguments are needed, a shell function should be  used  (see  F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS
       below).

       Aliases  are not expanded when the shell is not interactive, unless the
       e\bex\bxp\bpa\ban\bnd\bd_\b_a\bal\bli\bia\bas\bse\bes\bs shell option is set using s\bsh\bho\bop\bpt\bt (see the description  of
       s\bsh\bho\bop\bpt\bt under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

       The  rules  concerning  the  definition and use of aliases are somewhat
       confusing.  B\bBa\bas\bsh\bh 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 a\bal\bli\bia\bas\bs in com-
       pound commands.

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

F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS
       A shell function, defined  as  described  above  under  S\bSH\bHE\bEL\bLL\bL  G\bGR\bRA\bAM\bMM\bMA\bAR\bR,
       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 #\b# is
       updated to reflect the change.  Special parameter 0 is unchanged.   The
       first  element of the F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE 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 the exception that the D\bDE\bEB\bBU\bUG\bG trap (see the description of the t\btr\bra\bap\bp
       builtin under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below) is not inherited unless the
       function has been given the t\btr\bra\bac\bce\be attribute (see the description of the
       d\bde\bec\bcl\bla\bar\bre\be  builtin  below)  or  the  -\b-o\bo  f\bfu\bun\bnc\bct\btr\bra\bac\bce\be  shell option has been
       enabled with the s\bse\bet\bt builtin (in which case all functions  inherit  the
       D\bDE\bEB\bBU\bUG\bG trap).

       Variables  local to the function may be declared with the l\blo\boc\bca\bal\bl builtin
       command.  Ordinarily, variables and their values are shared between the
       function and its caller.

       If  the  builtin command r\bre\bet\btu\bur\brn\bn 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 R\bRE\bET\bTU\bUR\bRN\bN trap is executed
       before execution resumes.  When a function completes, the values of the
       positional  parameters  and the special parameter #\b# are restored to the
       values they had prior to the function's execution.

       Function names and definitions may be listed with the -\b-f\bf option to  the
       d\bde\bec\bcl\bla\bar\bre\be or t\bty\byp\bpe\bes\bse\bet\bt builtin commands.  The -\b-F\bF option to d\bde\bec\bcl\bla\bar\bre\be or t\bty\byp\bpe\be-\b-
       s\bse\bet\bt will list the function names only (and optionally the  source  file
       and  line  number, if the e\bex\bxt\btd\bde\beb\bbu\bug\bg shell option is enabled).  Functions
       may be exported so that subshells automatically have them defined  with
       the  -\b-f\bf  option  to  the e\bex\bxp\bpo\bor\brt\bt builtin.  Note that shell functions and
       variables with the same name may result in  multiple  identically-named
       entries in the environment passed to the shell's children.  Care should
       be taken in cases where this may cause a problem.

       Functions may be recursive.  No limit  is  imposed  on  the  number  of
       recursive calls.

A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN
       The  shell allows arithmetic expressions to be evaluated, under certain
       circumstances (see the l\ble\bet\bt and d\bde\bec\bcl\bla\bar\bre\be builtin commands and  A\bAr\bri\bit\bth\bhm\bme\bet\bti\bic\bc
       E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn).   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.

       _\bi_\bd+\b++\b+ _\bi_\bd-\b--\b-
              variable post-increment and post-decrement
       +\b++\b+_\bi_\bd -\b--\b-_\bi_\bd
              variable pre-increment and pre-decrement
       -\b- +\b+    unary minus and plus
       !\b! ~\b~    logical and bitwise negation
       *\b**\b*     exponentiation
       *\b* /\b/ %\b%  multiplication, division, remainder
       +\b+ -\b-    addition, subtraction
       <\b<<\b< >\b>>\b>  left and right bitwise shifts
       <\b<=\b= >\b>=\b= <\b< >\b>
              comparison
       =\b==\b= !\b!=\b=  equality and inequality
       &\b&      bitwise AND
       ^\b^      bitwise exclusive OR
       |\b|      bitwise OR
       &\b&&\b&     logical AND
       |\b||\b|     logical OR
       _\be_\bx_\bp_\br?\b?_\be_\bx_\bp_\br:\b:_\be_\bx_\bp_\br
              conditional operator
       =\b= *\b*=\b= /\b/=\b= %\b%=\b= +\b+=\b= -\b-=\b= <\b<<\b<=\b= >\b>>\b>=\b= &\b&=\b= ^\b^=\b= |\b|=\b=
              assignment
       _\be_\bx_\bp_\br_\b1 ,\b, _\be_\bx_\bp_\br_\b2
              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  _\bi_\bn_\bt_\be_\bg_\be_\br
       attribute using d\bde\bec\bcl\bla\bar\bre\be -\b-i\bi is assigned a value.  A null value evaluates
       to 0.  A shell variable need not have its integer 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
       [_\bb_\ba_\bs_\be_\b#]n,  where _\bb_\ba_\bs_\be is a decimal number between 2 and 64 representing
       the arithmetic base, and _\bn is a number in that base.  If _\bb_\ba_\bs_\be_\b# is omit-
       ted,  then  base 10 is used.  The digits greater than 9 are represented
       by the lowercase letters, the uppercase letters,  @,  and  _,  in  that
       order.   If  _\bb_\ba_\bs_\be  is less than or equal to 36, lowercase and uppercase
       letters may be used interchangably to represent 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.

C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS
       Conditional  expressions  are  used  by the [\b[[\b[ compound command and the
       t\bte\bes\bst\bt and [\b[ builtin commands to test file attributes and perform  string
       and  arithmetic comparisons.  Expressions are formed from the following
       unary or binary primaries.  If any _\bf_\bi_\bl_\be argument to  one  of  the  pri-
       maries is of the form _\b/_\bd_\be_\bv_\b/_\bf_\bd_\b/_\bn, then file descriptor _\bn is checked.  If
       the _\bf_\bi_\bl_\be argument to  one  of  the  primaries  is  one  of  _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bi_\bn,
       _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bo_\bu_\bt,  or _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\be_\br_\br, 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.

       -\b-a\ba _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists.
       -\b-b\bb _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a block special file.
       -\b-c\bc _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a character special file.
       -\b-d\bd _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a directory.
       -\b-e\be _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists.
       -\b-f\bf _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a regular file.
       -\b-g\bg _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is set-group-id.
       -\b-h\bh _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a symbolic link.
       -\b-k\bk _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and its ``sticky'' bit is set.
       -\b-p\bp _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a named pipe (FIFO).
       -\b-r\br _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is readable.
       -\b-s\bs _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and has a size greater than zero.
       -\b-t\bt _\bf_\bd  True if file descriptor _\bf_\bd is open and refers to a terminal.
       -\b-u\bu _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and its set-user-id bit is set.
       -\b-w\bw _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is writable.
       -\b-x\bx _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is executable.
       -\b-O\bO _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is owned by the effective user id.
       -\b-G\bG _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is owned by the effective group id.
       -\b-L\bL _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a symbolic link.
       -\b-S\bS _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and is a socket.
       -\b-N\bN _\bf_\bi_\bl_\be
              True if _\bf_\bi_\bl_\be exists and has been  modified  since  it  was  last
              read.
       _\bf_\bi_\bl_\be_\b1 -n\bnt\bt _\bf_\bi_\bl_\be_\b2
              True  if  _\bf_\bi_\bl_\be_\b1  is  newer (according to modification date) than
              _\bf_\bi_\bl_\be_\b2, or if _\bf_\bi_\bl_\be_\b1 exists and _\bf_\bi_\bl_\be_\b2 does not.
       _\bf_\bi_\bl_\be_\b1 -o\bot\bt _\bf_\bi_\bl_\be_\b2
              True if _\bf_\bi_\bl_\be_\b1 is older than _\bf_\bi_\bl_\be_\b2, or if _\bf_\bi_\bl_\be_\b2 exists and  _\bf_\bi_\bl_\be_\b1
              does not.
       _\bf_\bi_\bl_\be_\b1 -\b-e\bef\bf _\bf_\bi_\bl_\be_\b2
              True  if _\bf_\bi_\bl_\be_\b1 and _\bf_\bi_\bl_\be_\b2 refer to the same device and inode num-
              bers.
       -\b-o\bo _\bo_\bp_\bt_\bn_\ba_\bm_\be
              True if shell option  _\bo_\bp_\bt_\bn_\ba_\bm_\be  is  enabled.   See  the  list  of
              options  under  the  description  of  the  -\b-o\bo  option to the s\bse\bet\bt
              builtin below.
       -\b-z\bz _\bs_\bt_\br_\bi_\bn_\bg
              True if the length of _\bs_\bt_\br_\bi_\bn_\bg is zero.
       _\bs_\bt_\br_\bi_\bn_\bg
       -\b-n\bn _\bs_\bt_\br_\bi_\bn_\bg
              True if the length of _\bs_\bt_\br_\bi_\bn_\bg is non-zero.

       _\bs_\bt_\br_\bi_\bn_\bg_\b1 =\b==\b= _\bs_\bt_\br_\bi_\bn_\bg_\b2
              True if the strings are equal.  =\b= may be used in place of =\b==\b= for
              strict POSIX compliance.

       _\bs_\bt_\br_\bi_\bn_\bg_\b1 !\b!=\b= _\bs_\bt_\br_\bi_\bn_\bg_\b2
              True if the strings are not equal.

       _\bs_\bt_\br_\bi_\bn_\bg_\b1 <\b< _\bs_\bt_\br_\bi_\bn_\bg_\b2
              True  if  _\bs_\bt_\br_\bi_\bn_\bg_\b1  sorts before _\bs_\bt_\br_\bi_\bn_\bg_\b2 lexicographically in the
              current locale.

       _\bs_\bt_\br_\bi_\bn_\bg_\b1 >\b> _\bs_\bt_\br_\bi_\bn_\bg_\b2
              True if _\bs_\bt_\br_\bi_\bn_\bg_\b1 sorts after  _\bs_\bt_\br_\bi_\bn_\bg_\b2  lexicographically  in  the
              current locale.

       _\ba_\br_\bg_\b1 O\bOP\bP _\ba_\br_\bg_\b2
              O\bOP\bP  is one of -\b-e\beq\bq, -\b-n\bne\be, -\b-l\blt\bt, -\b-l\ble\be, -\b-g\bgt\bt, or -\b-g\bge\be.  These arithmetic
              binary operators return true if _\ba_\br_\bg_\b1 is equal to, not equal  to,
              less  than, less than or equal to, greater than, or greater than
              or equal to _\ba_\br_\bg_\b2, respectively.  _\bA_\br_\bg_\b1 and _\ba_\br_\bg_\b2 may  be  positive
              or negative integers.

S\bSI\bIM\bMP\bPL\bLE\bE C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
       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 R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN.

       4.     The text after the =\b= 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.

C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN
       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 F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS.  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, b\bba\bas\bsh\bh searches each element of the P\bPA\bAT\bTH\bH for  a  directory  con-
       taining  an  executable  file  by that name.  B\bBa\bas\bsh\bh uses a hash table to
       remember the full pathnames of executable files (see h\bha\bas\bsh\bh  under  S\bSH\bHE\bEL\bLL\bL
       B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  below).  A full search of the directories in P\bPA\bAT\bTH\bH is
       performed only if the command is not found in the hash table.   If  the
       search  is  unsuccessful, 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 _\bs_\bh_\be_\bl_\bl _\bs_\bc_\br_\bi_\bp_\bt,  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  h\bha\bas\bsh\bh  below
       under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS) are retained by the child.

       If  the program is a file beginning with #\b#!\b!, 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.

C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN E\bEN\bNV\bVI\bIR\bRO\bON\bNM\bME\bEN\bNT\bT
       The  shell  has an _\be_\bx_\be_\bc_\bu_\bt_\bi_\bo_\bn _\be_\bn_\bv_\bi_\br_\bo_\bn_\bm_\be_\bn_\bt, which consists of the follow-
       ing:


       +\bo      open files inherited by the shell at invocation, as modified  by
              redirections supplied to the e\bex\bxe\bec\bc builtin

       +\bo      the  current  working directory as set by c\bcd\bd, p\bpu\bus\bsh\bhd\bd, or p\bpo\bop\bpd\bd, or
              inherited by the shell at invocation

       +\bo      the file creation mode mask as set by u\bum\bma\bas\bsk\bk  or  inherited  from
              the shell's parent

       +\bo      current traps set by t\btr\bra\bap\bp

       +\bo      shell parameters that are set by variable assignment or with s\bse\bet\bt
              or inherited from the shell's parent in the environment

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

       +\bo      options  enabled  at  invocation (either by default or with com-
              mand-line arguments) or by s\bse\bet\bt

       +\bo      options enabled by s\bsh\bho\bop\bpt\bt

       +\bo      shell aliases defined with a\bal\bli\bia\bas\bs

       +\bo      various process IDs, including those  of  background  jobs,  the
              value of $\b$$\b$, and the value of $\b$P\bPP\bPI\bID\bD

       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.


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

       +\bo      the current working directory

       +\bo      the file creation mode mask

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

       +\bo      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  asyn-
       chronous  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 invocation.  Builtin commands that are invoked as part of a pipeline
       are  also executed in a subshell environment.  Changes made to the sub-
       shell environment cannot affect the shell's execution environment.

       If a command is followed by a &\b& and job  control  is  not  active,  the
       default  standard  input  for  the command is the empty file _\b/_\bd_\be_\bv_\b/_\bn_\bu_\bl_\bl.
       Otherwise, the invoked command inherits the  file  descriptors  of  the
       calling shell as modified by redirections.

E\bEN\bNV\bVI\bIR\bRO\bON\bNM\bME\bEN\bNT\bT
       When  a  program  is invoked it is given an array of strings called the
       _\be_\bn_\bv_\bi_\br_\bo_\bn_\bm_\be_\bn_\bt.   This  is  a  list  of  _\bn_\ba_\bm_\be-_\bv_\ba_\bl_\bu_\be  pairs,  of  the  form
       _\bn_\ba_\bm_\be=_\bv_\ba_\bl_\bu_\be.

       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 _\be_\bx_\bp_\bo_\br_\bt to child pro-
       cesses.  Executed commands inherit the  environment.   The  e\bex\bxp\bpo\bor\brt\bt  and
       d\bde\bec\bcl\bla\bar\bre\be  -\b-x\bx  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  u\bun\bns\bse\bet\bt  command,  plus
       any additions via the e\bex\bxp\bpo\bor\brt\bt and d\bde\bec\bcl\bla\bar\bre\be -\b-x\bx commands.

       The  environment  for  any  _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd or function may be augmented
       temporarily by prefixing it with parameter  assignments,  as  described
       above in P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS.  These assignment statements affect only the envi-
       ronment seen by that command.

       If the -\b-k\bk option is set (see the s\bse\bet\bt builtin command below),  then  _\ba_\bl_\bl
       parameter  assignments are placed in the environment for a command, not
       just those that precede the command name.

       When b\bba\bas\bsh\bh invokes an external command, the variable _\b_  is  set  to  the
       full  file  name of the command and passed to that command in its envi-
       ronment.

E\bEX\bXI\bIT\bT S\bST\bTA\bAT\bTU\bUS\bS
       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 _\bN, b\bba\bas\bsh\bh uses the value of 128+_\bN 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 (_\bt_\br_\bu_\be) if  successful,  and
       non-zero  (_\bf_\ba_\bl_\bs_\be)  if an error occurs while they execute.  All builtins
       return an exit status of 2 to indicate incorrect usage.

       B\bBa\bas\bsh\bh 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 e\bex\bxi\bit\bt builtin command below.

S\bSI\bIG\bGN\bNA\bAL\bLS\bS
       When b\bba\bas\bsh\bh is interactive, in the  absence  of  any  traps,  it  ignores
       S\bSI\bIG\bGT\bTE\bER\bRM\bM (so that k\bki\bil\bll\bl 0\b0 does not kill an interactive shell), and S\bSI\bIG\bGI\bIN\bNT\bT
       is caught and handled (so that the w\bwa\bai\bit\bt builtin is interruptible).   In
       all  cases,  b\bba\bas\bsh\bh  ignores  S\bSI\bIG\bGQ\bQU\bUI\bIT\bT.  If job control is in effect, b\bba\bas\bsh\bh
       ignores S\bSI\bIG\bGT\bTT\bTI\bIN\bN, S\bSI\bIG\bGT\bTT\bTO\bOU\bU, and S\bSI\bIG\bGT\bTS\bST\bTP\bP.

       Non-builtin commands run by b\bba\bas\bsh\bh have signal handlers set to the values
       inherited  by  the  shell  from its parent.  When job control is not in
       effect, asynchronous commands ignore S\bSI\bIG\bGI\bIN\bNT\bT and S\bSI\bIG\bGQ\bQU\bUI\bIT\bT in addition  to
       these  inherited handlers.  Commands run as a result of command substi-
       tution ignore the keyboard-generated job control signals S\bSI\bIG\bGT\bTT\bTI\bIN\bN, S\bSI\bIG\bGT\bT-\b-
       T\bTO\bOU\bU, and S\bSI\bIG\bGT\bTS\bST\bTP\bP.

       The  shell  exits by default upon receipt of a S\bSI\bIG\bGH\bHU\bUP\bP.  Before exiting,
       an interactive shell  resends  the  S\bSI\bIG\bGH\bHU\bUP\bP  to  all  jobs,  running  or
       stopped.  Stopped jobs are sent S\bSI\bIG\bGC\bCO\bON\bNT\bT to ensure that they receive the
       S\bSI\bIG\bGH\bHU\bUP\bP.  To prevent the shell from sending the signal to  a  particular
       job,  it  should be removed from the jobs table with the d\bdi\bis\bso\bow\bwn\bn builtin
       (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below) or  marked  to  not  receive  S\bSI\bIG\bGH\bHU\bUP\bP
       using d\bdi\bis\bso\bow\bwn\bn -\b-h\bh.

       If  the  h\bhu\bup\bpo\bon\bne\bex\bxi\bit\bt  shell  option has been set with s\bsh\bho\bop\bpt\bt, b\bba\bas\bsh\bh sends a
       S\bSI\bIG\bGH\bHU\bUP\bP to all jobs when an interactive login shell exits.

       If 0for which a trap has been set, the trap will not be executed  until
       the  command  completes.  When b\bba\bas\bsh\bh is waiting for an asynchronous com-
       mand via the w\bwa\bai\bit\bt builtin, the reception of a signal for which  a  trap
       has  been set will cause the w\bwa\bai\bit\bt builtin to return immediately with an
       exit status greater than 128, immediately after which the trap is  exe-
       cuted.

J\bJO\bOB\bB C\bCO\bON\bNT\bTR\bRO\bOL\bL
       _\bJ_\bo_\bb  _\bc_\bo_\bn_\bt_\br_\bo_\bl  refers  to  the ability to selectively stop (_\bs_\bu_\bs_\bp_\be_\bn_\bd) the
       execution of processes and continue (_\br_\be_\bs_\bu_\bm_\be) their execution at a later
       point.   A  user  typically  employs  this  facility via an interactive
       interface supplied jointly by the system's terminal driver and b\bba\bas\bsh\bh.

       The shell associates a _\bj_\bo_\bb with each pipeline.  It  keeps  a  table  of
       currently  executing  jobs,  which may be listed with the j\bjo\bob\bbs\bs command.
       When b\bba\bas\bsh\bh starts a job asynchronously (in the _\bb_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd), 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.  B\bBa\bas\bsh\bh
       uses the _\bj_\bo_\bb 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 _\bc_\bu_\br_\br_\be_\bn_\bt _\bt_\be_\br_\bm_\bi_\bn_\ba_\bl _\bp_\br_\bo_\bc_\be_\bs_\bs
       _\bg_\br_\bo_\bu_\bp _\bI_\bD.  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 S\bSI\bIG\bGI\bIN\bNT\bT.  These processes are said  to  be  in
       the  _\bf_\bo_\br_\be_\bg_\br_\bo_\bu_\bn_\bd.  _\bB_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd 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
       write to the terminal.  Background processes which attempt to read from
       (write to) the terminal are sent a S\bSI\bIG\bGT\bTT\bTI\bIN\bN (\b(S\bSI\bIG\bGT\bTT\bTO\bOU\bU)\b) signal by the ter-
       minal driver, which, unless caught, suspends the process.

       If the operating system on which b\bba\bas\bsh\bh is running supports job  control,
       b\bba\bas\bsh\bh contains facilities to use it.  Typing the _\bs_\bu_\bs_\bp_\be_\bn_\bd character (typ-
       ically ^\b^Z\bZ, Control-Z) while a process is running causes that process to
       be  stopped  and  returns  control to b\bba\bas\bsh\bh.  Typing the _\bd_\be_\bl_\ba_\by_\be_\bd _\bs_\bu_\bs_\bp_\be_\bn_\bd
       character (typically ^\b^Y\bY, Control-Y) causes the process  to  be  stopped
       when  it  attempts  to  read input from the terminal, and control to be
       returned to b\bba\bas\bsh\bh.  The user may then manipulate the state of this  job,
       using  the  b\bbg\bg command to continue it in the background, the f\bfg\bg command
       to continue it in the foreground, or the k\bki\bil\bll\bl command to kill it.  A ^\b^Z\bZ
       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 %\b% introduces a job name.  Job number _\bn may be referred to as %\b%n\bn.  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 exam-
       ple, %\b%c\bce\be refers to a stopped c\bce\be job.  If a prefix matches more than one
       job,  b\bba\bas\bsh\bh  reports an error.  Using %\b%?\b?c\bce\be, on the other hand, refers to
       any job containing the string c\bce\be in its command line.  If the substring
       matches  more  than one job, b\bba\bas\bsh\bh reports an error.  The symbols %\b%%\b% and
       %\b%+\b+ refer to the shell's notion of the _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb, which  is  the  last
       job  stopped  while  it  was  in the foreground or started in the back-
       ground.  The _\bp_\br_\be_\bv_\bi_\bo_\bu_\bs _\bj_\bo_\bb  may  be  referenced  using  %\b%-\b-.   In  output
       pertaining  to jobs (e.g., the output of the j\bjo\bob\bbs\bs command), the current
       job is always flagged with a +\b+, and the previous job with a -\b-.

       Simply naming a job can be used to bring it into the foreground: %\b%1\b1  is
       a  synonym  for  `\b``\b`f\bfg\bg %\b%1\b1'\b''\b', bringing job 1 from the background into the
       foreground.  Similarly, `\b``\b`%\b%1\b1 &\b&'\b''\b'  resumes  job  1  in  the  background,
       equivalent to `\b``\b`b\bbg\bg %\b%1\b1'\b''\b'.

       The  shell  learns immediately whenever a job changes state.  Normally,
       b\bba\bas\bsh\bh 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 -\b-b\bb
       option to the s\bse\bet\bt builtin command is enabled, b\bba\bas\bsh\bh reports such changes
       immediately.   Any  trap  on  S\bSI\bIG\bGC\bCH\bHL\bLD\bD  is  executed for each child that
       exits.

       If an attempt to exit b\bba\bas\bsh\bh is made while jobs are  stopped,  the  shell
       prints a warning message.  The j\bjo\bob\bbs\bs command may then be used to inspect
       their status.  If a second attempt to exit is made without an interven-
       ing  command, the shell does not print another warning, and the stopped
       jobs are terminated.

P\bPR\bRO\bOM\bMP\bPT\bTI\bIN\bNG\bG
       When executing interactively, b\bba\bas\bsh\bh displays the primary prompt P\bPS\bS1\b1 when
       it  is  ready  to  read a command, and the secondary prompt P\bPS\bS2\b2 when it
       needs more input to complete  a  command.   B\bBa\bas\bsh\bh  allows  these  prompt
       strings  to  be  customized  by inserting a number of backslash-escaped
       special characters that are decoded as follows:
              \\b\a\ba     an ASCII bell character (07)
              \\b\d\bd     the date in "Weekday Month Date" format (e.g.,  "Tue  May
                     26")
              \\b\D\bD{\b{_\bf_\bo_\br_\bm_\ba_\bt}\b}
                     the  _\bf_\bo_\br_\bm_\ba_\bt  is  passed  to _\bs_\bt_\br_\bf_\bt_\bi_\bm_\be(3) and the result is
                     inserted into the prompt string; an empty _\bf_\bo_\br_\bm_\ba_\bt  results
                     in a locale-specific time representation.  The braces are
                     required
              \\b\e\be     an ASCII escape character (033)
              \\b\h\bh     the hostname up to the first `.'
              \\b\H\bH     the hostname
              \\b\j\bj     the number of jobs currently managed by the shell
              \\b\l\bl     the basename of the shell's terminal device name
              \\b\n\bn     newline
              \\b\r\br     carriage return
              \\b\s\bs     the name of the shell, the basename of  $\b$0\b0  (the  portion
                     following the final slash)
              \\b\t\bt     the current time in 24-hour HH:MM:SS format
              \\b\T\bT     the current time in 12-hour HH:MM:SS format
              \\b\@\b@     the current time in 12-hour am/pm format
              \\b\A\bA     the current time in 24-hour HH:MM format
              \\b\u\bu     the username of the current user
              \\b\v\bv     the version of b\bba\bas\bsh\bh (e.g., 2.00)
              \\b\V\bV     the release of b\bba\bas\bsh\bh, version + patch level (e.g., 2.00.0)
              \\b\w\bw     the current working  directory,  with  $\b$H\bHO\bOM\bME\bE  abbreviated
                     with a tilde
              \\b\W\bW     the basename of the current working directory, with $\b$H\bHO\bOM\bME\bE
                     abbreviated with a tilde
              \\b\!\b!     the history number of this command
              \\b\#\b#     the command number of this command
              \\b\$\b$     if the effective UID is 0, a #\b#, otherwise a $\b$
              \\b\_\bn_\bn_\bn   the character corresponding to the octal number _\bn_\bn_\bn
              \\b\\\b\     a backslash
              \\b\[\b[     begin a sequence of non-printing characters, which  could
                     be  used  to  embed  a terminal control sequence into the
                     prompt
              \\b\]\b]     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  H\bHI\bIS\bST\bTO\bOR\bRY\bY
       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  p\bpr\bro\bom\bmp\bpt\btv\bva\bar\brs\bs  shell option (see the description of the s\bsh\bho\bop\bpt\bt command
       under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE
       This is the library that handles reading input when using  an  interac-
       tive shell, unless the -\b--\b-n\bno\boe\bed\bdi\bit\bti\bin\bng\bg option is given at shell invocation.
       By default, the line editing commands are similar to those of emacs.  A
       vi-style  line  editing  interface is also available.  To turn off line
       editing after the shell is running, use the +\b+o\bo e\bem\bma\bac\bcs\bs or +\b+o\bo  v\bvi\bi  options
       to the s\bse\bet\bt builtin (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

   R\bRe\bea\bad\bdl\bli\bin\bne\be N\bNo\bot\bta\bat\bti\bio\bon\bn
       In this section, the emacs-style notation is used to denote keystrokes.
       Control keys are denoted by C-_\bk_\be_\by, e.g., C-n  means  Control-N.   Simi-
       larly,  _\bm_\be_\bt_\ba  keys are denoted by M-_\bk_\be_\by, so M-x means Meta-X.  (On key-
       boards without a _\bm_\be_\bt_\ba key, M-_\bx means ESC _\bx, i.e., press the Escape  key
       then the _\bx key.  This makes ESC the _\bm_\be_\bt_\ba _\bp_\br_\be_\bf_\bi_\bx.  The combination M-C-_\bx
       means ESC-Control-_\bx, or press the Escape key then hold the Control  key
       while pressing the _\bx key.)

       Readline commands may be given numeric _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs, 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., k\bki\bil\bll\bl-\b-l\bli\bin\bne\be) 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 _\bk_\bi_\bl_\bl_\bi_\bn_\bg text, the text deleted is  saved
       for possible future retrieval (_\by_\ba_\bn_\bk_\bi_\bn_\bg).  The killed text is saved in a
       _\bk_\bi_\bl_\bl _\br_\bi_\bn_\bg.  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.

   R\bRe\bea\bad\bdl\bli\bin\bne\be I\bIn\bni\bit\bti\bia\bal\bli\biz\bza\bat\bti\bio\bon\bn
       Readline is customized by putting commands in  an  initialization  file
       (the  _\bi_\bn_\bp_\bu_\bt_\br_\bc  file).  The name of this file is taken from the value of
       the I\bIN\bNP\bPU\bUT\bTR\bRC\bC variable.  If  that  variable  is  unset,  the  default  is
       _\b~_\b/_\b._\bi_\bn_\bp_\bu_\bt_\br_\bc.   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
       #\b#  are  comments.   Lines  beginning with a $\b$ indicate conditional con-
       structs.  Other lines denote key bindings and variable settings.

       The default key-bindings may be changed with an  _\bi_\bn_\bp_\bu_\bt_\br_\bc  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 _\bi_\bn_\bp_\bu_\bt_\br_\bc would make M-C-u execute the readline command  _\bu_\bn_\bi_\bv_\be_\br_\b-
       _\bs_\ba_\bl_\b-_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt.

       The  following  symbolic  character  names are recognized: _\bR_\bU_\bB_\bO_\bU_\bT, _\bD_\bE_\bL,
       _\bE_\bS_\bC, _\bL_\bF_\bD, _\bN_\bE_\bW_\bL_\bI_\bN_\bE, _\bR_\bE_\bT, _\bR_\bE_\bT_\bU_\bR_\bN, _\bS_\bP_\bC, _\bS_\bP_\bA_\bC_\bE, and _\bT_\bA_\bB.

       In addition to command names, readline allows keys to  be  bound  to  a
       string that is inserted when the key is pressed (a _\bm_\ba_\bc_\br_\bo).

   R\bRe\bea\bad\bdl\bli\bin\bne\be K\bKe\bey\by B\bBi\bin\bnd\bdi\bin\bng\bgs\bs
       The  syntax for controlling key bindings in the _\bi_\bn_\bp_\bu_\bt_\br_\bc 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 _\bM_\be_\bt_\ba_\b- or
       _\bC_\bo_\bn_\bt_\br_\bo_\bl_\b- prefixes, or as a key sequence.

       When using the form k\bke\bey\byn\bna\bam\bme\be:_\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be or _\bm_\ba_\bc_\br_\bo, _\bk_\be_\by_\bn_\ba_\bm_\be 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, _\bC_\b-_\bu is bound to the function  u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt,
       _\bM_\b-_\bD_\bE_\bL  is bound to the function b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-k\bki\bil\bll\bl-\b-w\bwo\bor\brd\bd, and _\bC_\b-_\bo 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,  "\b"k\bke\bey\bys\bse\beq\bq"\b":_\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be or _\bm_\ba_\bc_\br_\bo, k\bke\bey\bys\bse\beq\bq differs
       from k\bke\bey\byn\bna\bam\bme\be 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, _\bC_\b-_\bu is again bound to the function u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt.
       _\bC_\b-_\bx _\bC_\b-_\br is bound to the function r\bre\be-\b-r\bre\bea\bad\bd-\b-i\bin\bni\bit\bt-\b-f\bfi\bil\ble\be, and _\bE_\bS_\bC _\b[ _\b1 _\b1 _\b~  is
       bound to insert the text ``Function Key 1''.

       The full set of GNU Emacs style escape sequences is
              \\b\C\bC-\b-    control prefix
              \\b\M\bM-\b-    meta prefix
              \\b\e\be     an escape character
              \\b\\\b\     backslash
              \\b\"\b"     literal "
              \\b\'\b'     literal '

       In  addition  to  the GNU Emacs style escape sequences, a second set of
       backslash escapes is available:
              \\b\a\ba     alert (bell)
              \\b\b\bb     backspace
              \\b\d\bd     delete
              \\b\f\bf     form feed
              \\b\n\bn     newline
              \\b\r\br     carriage return
              \\b\t\bt     horizontal tab
              \\b\v\bv     vertical tab
              \\b\_\bn_\bn_\bn   the eight-bit character whose value is  the  octal  value
                     _\bn_\bn_\bn (one to three digits)
              \\b\x\bx_\bH_\bH   the  eight-bit  character  whose value is the hexadecimal
                     value _\bH_\bH (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 '.

       B\bBa\bas\bsh\bh allows the current readline key bindings to be displayed or  modi-
       fied  with  the b\bbi\bin\bnd\bd builtin command.  The editing mode may be switched
       during interactive use by using the -\b-o\bo option to the s\bse\bet\bt  builtin  com-
       mand (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).

   R\bRe\bea\bad\bdl\bli\bin\bne\be V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs
       Readline has variables that can be used to further customize its behav-
       ior.  A variable may be set in the _\bi_\bn_\bp_\bu_\bt_\br_\bc file with a statement of the
       form

              s\bse\bet\bt _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be_\b-_\bn_\ba_\bm_\be _\bv_\ba_\bl_\bu_\be

       Except  where  noted, readline variables can take the values O\bOn\bn or O\bOf\bff\bf.
       The variables and their default values are:

       b\bbe\bel\bll\bl-\b-s\bst\bty\byl\ble\be (\b(a\bau\bud\bdi\bib\bbl\ble\be)\b)
              Controls what happens when readline wants to ring  the  terminal
              bell.  If set to n\bno\bon\bne\be, readline never rings the bell.  If set to
              v\bvi\bis\bsi\bib\bbl\ble\be, readline uses a visible bell if one is  available.   If
              set to a\bau\bud\bdi\bib\bbl\ble\be, readline attempts to ring the terminal's bell.
       c\bco\bom\bmm\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn (\b(`\b``\b`#\b#'\b''\b')\b)
              The  string  that  is  inserted when the readline i\bin\bns\bse\ber\brt\bt-\b-c\bco\bom\bmm\bme\ben\bnt\bt
              command is executed.  This command is bound to M\bM-\b-#\b# in emacs mode
              and to #\b# in vi command mode.
       c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-i\big\bgn\bno\bor\bre\be-\b-c\bca\bas\bse\be (\b(O\bOf\bff\bf)\b)
              If set to O\bOn\bn, readline performs filename matching and completion
              in a case-insensitive fashion.
       c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-q\bqu\bue\ber\bry\by-\b-i\bit\bte\bem\bms\bs (\b(1\b10\b00\b0)\b)
              This determines when the user is queried about viewing the  num-
              ber  of  possible  completions generated by the p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\be-\b-
              t\bti\bio\bon\bns\bs 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.
       c\bco\bon\bnv\bve\ber\brt\bt-\b-m\bme\bet\bta\ba (\b(O\bOn\bn)\b)
              If set to O\bOn\bn, 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
              _\bm_\be_\bt_\ba _\bp_\br_\be_\bf_\bi_\bx).
       d\bdi\bis\bsa\bab\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn (\b(O\bOf\bff\bf)\b)
              If set to O\bOn\bn, readline will inhibit word completion.  Completion
              characters will be inserted into the line as if  they  had  been
              mapped to s\bse\bel\blf\bf-\b-i\bin\bns\bse\ber\brt\bt.
       e\bed\bdi\bit\bti\bin\bng\bg-\b-m\bmo\bod\bde\be (\b(e\bem\bma\bac\bcs\bs)\b)
              Controls whether readline begins with a set of key bindings sim-
              ilar to _\be_\bm_\ba_\bc_\bs or _\bv_\bi.  e\bed\bdi\bit\bti\bin\bng\bg-\b-m\bmo\bod\bde\be can be set to either e\bem\bma\bac\bcs\bs or
              v\bvi\bi.
       e\ben\bna\bab\bbl\ble\be-\b-k\bke\bey\byp\bpa\bad\bd (\b(O\bOf\bff\bf)\b)
              When set to O\bOn\bn, readline will try to enable the application key-
              pad when it is called.  Some systems need  this  to  enable  the
              arrow keys.
       e\bex\bxp\bpa\ban\bnd\bd-\b-t\bti\bil\bld\bde\be (\b(O\bOf\bff\bf)\b)
              If  set  to  o\bon\bn,  tilde  expansion  is  performed  when readline
              attempts word completion.
       h\bhi\bis\bst\bto\bor\bry\by-\b-p\bpr\bre\bes\bse\ber\brv\bve\be-\b-p\bpo\boi\bin\bnt\bt
              If set to o\bon\bn, the history code attempts to place  point  at  the
              same  location  on each history line retrived with p\bpr\bre\bev\bvi\bio\bou\bus\bs-\b-h\bhi\bis\bs-\b-
              t\bto\bor\bry\by or n\bne\bex\bxt\bt-\b-h\bhi\bis\bst\bto\bor\bry\by.
       h\bho\bor\bri\biz\bzo\bon\bnt\bta\bal\bl-\b-s\bsc\bcr\bro\bol\bll\bl-\b-m\bmo\bod\bde\be (\b(O\bOf\bff\bf)\b)
              When set to O\bOn\bn, 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.
       i\bin\bnp\bpu\but\bt-\b-m\bme\bet\bta\ba (\b(O\bOf\bff\bf)\b)
              If  set to O\bOn\bn, 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
              m\bme\bet\bta\ba-\b-f\bfl\bla\bag\bg is a synonym for this variable.
       i\bis\bse\bea\bar\brc\bch\bh-\b-t\bte\ber\brm\bmi\bin\bna\bat\bto\bor\brs\bs (\b(`\b``\b`C\bC-\b-[\b[C\bC-\b-J\bJ'\b''\b')\b)
              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 _\bE_\bS_\bC and _\bC_\b-_\bJ will terminate an incremental search.
       k\bke\bey\bym\bma\bap\bp (\b(e\bem\bma\bac\bcs\bs)\b)
              Set  the current readline keymap.  The set of valid keymap names
              is _\be_\bm_\ba_\bc_\bs_\b, _\be_\bm_\ba_\bc_\bs_\b-_\bs_\bt_\ba_\bn_\bd_\ba_\br_\bd_\b, _\be_\bm_\ba_\bc_\bs_\b-_\bm_\be_\bt_\ba_\b,  _\be_\bm_\ba_\bc_\bs_\b-_\bc_\bt_\bl_\bx_\b,  _\bv_\bi_\b,  _\bv_\bi_\b-_\bc_\bo_\bm_\b-
              _\bm_\ba_\bn_\bd,  and  _\bv_\bi_\b-_\bi_\bn_\bs_\be_\br_\bt.  _\bv_\bi is equivalent to _\bv_\bi_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd; _\be_\bm_\ba_\bc_\bs is
              equivalent to _\be_\bm_\ba_\bc_\bs_\b-_\bs_\bt_\ba_\bn_\bd_\ba_\br_\bd.  The default value is  _\be_\bm_\ba_\bc_\bs;  the
              value of e\bed\bdi\bit\bti\bin\bng\bg-\b-m\bmo\bod\bde\be also affects the default keymap.
       m\bma\bar\brk\bk-\b-d\bdi\bir\bre\bec\bct\bto\bor\bri\bie\bes\bs (\b(O\bOn\bn)\b)
              If set to O\bOn\bn, completed directory names have a slash appended.
       m\bma\bar\brk\bk-\b-m\bmo\bod\bdi\bif\bfi\bie\bed\bd-\b-l\bli\bin\bne\bes\bs (\b(O\bOf\bff\bf)\b)
              If  set  to  O\bOn\bn,  history lines that have been modified are dis-
              played with a preceding asterisk (*\b*).
       m\bma\bar\brk\bk-\b-s\bsy\bym\bml\bli\bin\bnk\bke\bed\bd-\b-d\bdi\bir\bre\bec\bct\bto\bor\bri\bie\bes\bs (\b(O\bOf\bff\bf)\b)
              If set to O\bOn\bn, completed names which are symbolic links to direc-
              tories   have   a  slash  appended  (subject  to  the  value  of
              m\bma\bar\brk\bk-\b-d\bdi\bir\bre\bec\bct\bto\bor\bri\bie\bes\bs).
       m\bma\bat\btc\bch\bh-\b-h\bhi\bid\bdd\bde\ben\bn-\b-f\bfi\bil\ble\bes\bs (\b(O\bOn\bn)\b)
              This variable, when set to O\bOn\bn, causes readline  to  match  files
              whose  names  begin  with  a  `.' (hidden files) when performing
              filename completion, unless the leading `.' is supplied  by  the
              user in the filename to be completed.
       o\bou\but\btp\bpu\but\bt-\b-m\bme\bet\bta\ba (\b(O\bOf\bff\bf)\b)
              If  set  to O\bOn\bn, readline will display characters with the eighth
              bit set directly rather than as a meta-prefixed escape sequence.
       p\bpa\bag\bge\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(O\bOn\bn)\b)
              If  set to O\bOn\bn, readline uses an internal _\bm_\bo_\br_\be-like pager to dis-
              play a screenful of possible completions at a time.
       p\bpr\bri\bin\bnt\bt-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs-\b-h\bho\bor\bri\biz\bzo\bon\bnt\bta\bal\bll\bly\by (\b(O\bOf\bff\bf)\b)
              If set to O\bOn\bn, readline will  display  completions  with  matches
              sorted  horizontally in alphabetical order, rather than down the
              screen.
       s\bsh\bho\bow\bw-\b-a\bal\bll\bl-\b-i\bif\bf-\b-a\bam\bmb\bbi\big\bgu\buo\bou\bus\bs (\b(O\bOf\bff\bf)\b)
              This alters the default behavior of  the  completion  functions.
              If set to o\bon\bn, words which have more than one possible completion
              cause the matches to be listed immediately  instead  of  ringing
              the bell.
       s\bsh\bho\bow\bw-\b-a\bal\bll\bl-\b-i\bif\bf-\b-u\bun\bnm\bmo\bod\bdi\bif\bfi\bie\bed\bd (\b(O\bOf\bff\bf)\b)
              This  alters the default behavior of the completion functions in
              a fashion similar to s\bsh\bho\bow\bw-\b-a\bal\bll\bl-\b-i\bif\bf-\b-a\bam\bmb\bbi\big\bgu\buo\bou\bus\bs.  If set to o\bon\bn, 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.
       v\bvi\bis\bsi\bib\bbl\ble\be-\b-s\bst\bta\bat\bts\bs (\b(O\bOf\bff\bf)\b)
              If set to O\bOn\bn, a character denoting a file's type as reported  by
              _\bs_\bt_\ba_\bt(2)  is  appended  to  the  filename  when  listing possible
              completions.

   R\bRe\bea\bad\bdl\bli\bin\bne\be C\bCo\bon\bnd\bdi\bit\bti\bio\bon\bna\bal\bl C\bCo\bon\bns\bst\btr\bru\buc\bct\bts\bs
       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.

       $\b$i\bif\bf    The  $\b$i\bif\bf 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.

              m\bmo\bod\bde\be   The m\bmo\bod\bde\be=\b= form of the  $\b$i\bif\bf  directive  is  used  to  test
                     whether  readline  is  in  emacs or vi mode.  This may be
                     used in conjunction with  the  s\bse\bet\bt  k\bke\bey\bym\bma\bap\bp  command,  for
                     instance,  to  set  bindings  in  the  _\be_\bm_\ba_\bc_\bs_\b-_\bs_\bt_\ba_\bn_\bd_\ba_\br_\bd and
                     _\be_\bm_\ba_\bc_\bs_\b-_\bc_\bt_\bl_\bx keymaps only if readline is  starting  out  in
                     emacs mode.

              t\bte\ber\brm\bm   The  t\bte\ber\brm\bm=\b=  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 =\b= is tested against the both full name of the ter-
                     minal  and  the  portion  of the terminal name before the
                     first -\b-.  This allows _\bs_\bu_\bn to match both _\bs_\bu_\bn and  _\bs_\bu_\bn_\b-_\bc_\bm_\bd,
                     for instance.

              a\bap\bpp\bpl\bli\bic\bca\bat\bti\bio\bon\bn
                     The a\bap\bpp\bpl\bli\bic\bca\bat\bti\bio\bon\bn construct is used to include application-
                     specific  settings.   Each  program  using  the  readline
                     library  sets the _\ba_\bp_\bp_\bl_\bi_\bc_\ba_\bt_\bi_\bo_\bn _\bn_\ba_\bm_\be, 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
                     Bash:

                     $\b$i\bif\bf Bash
                     # Quote the current or previous word
                     "\C-xq": "\eb\"\ef\""
                     $\b$e\ben\bnd\bdi\bif\bf

       $\b$e\ben\bnd\bdi\bif\bf This command, as seen in the previous example, terminates an $\b$i\bif\bf
              command.

       $\b$e\bel\bls\bse\be  Commands in this branch of the $\b$i\bif\bf directive are executed if the
              test fails.

       $\b$i\bin\bnc\bcl\blu\bud\bde\be
              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 _\b/_\be_\bt_\bc_\b/_\bi_\bn_\bp_\bu_\bt_\br_\bc:

              $\b$i\bin\bnc\bcl\blu\bud\bde\be  _\b/_\be_\bt_\bc_\b/_\bi_\bn_\bp_\bu_\bt_\br_\bc

   S\bSe\bea\bar\brc\bch\bhi\bin\bng\bg
       Readline provides commands for searching through  the  command  history
       (see H\bHI\bIS\bST\bTO\bOR\bRY\bY below) for lines containing a specified string.  There are
       two search modes: _\bi_\bn_\bc_\br_\be_\bm_\be_\bn_\bt_\ba_\bl and _\bn_\bo_\bn_\b-_\bi_\bn_\bc_\br_\be_\bm_\be_\bn_\bt_\ba_\bl.

       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 i\bis\bse\bea\bar\brc\bch\bh-\b-t\bte\ber\brm\bmi\bin\bna\bat\bto\bor\brs\bs 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 _\bn_\be_\bw_\bl_\bi_\bn_\be  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.

   R\bRe\bea\bad\bdl\bli\bin\bne\be C\bCo\bom\bmm\bma\ban\bnd\bd N\bNa\bam\bme\bes\bs
       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,  _\bp_\bo_\bi_\bn_\bt refers to the current cursor position, and _\bm_\ba_\br_\bk refers to
       a cursor position saved by the s\bse\bet\bt-\b-m\bma\bar\brk\bk command.  The text between  the
       point and mark is referred to as the _\br_\be_\bg_\bi_\bo_\bn.

   C\bCo\bom\bmm\bma\ban\bnd\bds\bs f\bfo\bor\br M\bMo\bov\bvi\bin\bng\bg
       b\bbe\beg\bgi\bin\bnn\bni\bin\bng\bg-\b-o\bof\bf-\b-l\bli\bin\bne\be (\b(C\bC-\b-a\ba)\b)
              Move to the start of the current line.
       e\ben\bnd\bd-\b-o\bof\bf-\b-l\bli\bin\bne\be (\b(C\bC-\b-e\be)\b)
              Move to the end of the line.
       f\bfo\bor\brw\bwa\bar\brd\bd-\b-c\bch\bha\bar\br (\b(C\bC-\b-f\bf)\b)
              Move forward a character.
       b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-c\bch\bha\bar\br (\b(C\bC-\b-b\bb)\b)
              Move back a character.
       f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-f\bf)\b)
              Move forward to the end of the next word.  Words are composed of
              alphanumeric characters (letters and digits).
       b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-b\bb)\b)
              Move back to the start of the current or previous  word.   Words
              are composed of alphanumeric characters (letters and digits).
       c\bcl\ble\bea\bar\br-\b-s\bsc\bcr\bre\bee\ben\bn (\b(C\bC-\b-l\bl)\b)
              Clear  the  screen  leaving  the  current line at the top of the
              screen.  With an argument,  refresh  the  current  line  without
              clearing the screen.
       r\bre\bed\bdr\bra\baw\bw-\b-c\bcu\bur\brr\bre\ben\bnt\bt-\b-l\bli\bin\bne\be
              Refresh the current line.

   C\bCo\bom\bmm\bma\ban\bnd\bds\bs f\bfo\bor\br M\bMa\ban\bni\bip\bpu\bul\bla\bat\bti\bin\bng\bg t\bth\bhe\be H\bHi\bis\bst\bto\bor\bry\by
       a\bac\bcc\bce\bep\bpt\bt-\b-l\bli\bin\bne\be (\b(N\bNe\bew\bwl\bli\bin\bne\be,\b, R\bRe\bet\btu\bur\brn\bn)\b)
              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 H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL variable.  If the line is a modified history
              line, then restore the history line to its original state.
       p\bpr\bre\bev\bvi\bio\bou\bus\bs-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(C\bC-\b-p\bp)\b)
              Fetch the previous command from the history list, moving back in
              the list.
       n\bne\bex\bxt\bt-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(C\bC-\b-n\bn)\b)
              Fetch  the next command from the history list, moving forward in
              the list.
       b\bbe\beg\bgi\bin\bnn\bni\bin\bng\bg-\b-o\bof\bf-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(M\bM-\b-<\b<)\b)
              Move to the first line in the history.
       e\ben\bnd\bd-\b-o\bof\bf-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(M\bM-\b->\b>)\b)
              Move to the end of the input history, i.e., the  line  currently
              being entered.
       r\bre\bev\bve\ber\brs\bse\be-\b-s\bse\bea\bar\brc\bch\bh-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(C\bC-\b-r\br)\b)
              Search  backward  starting  at  the current line and moving `up'
              through the  history  as  necessary.   This  is  an  incremental
              search.
       f\bfo\bor\brw\bwa\bar\brd\bd-\b-s\bse\bea\bar\brc\bch\bh-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(C\bC-\b-s\bs)\b)
              Search  forward  starting  at the current line and moving `down'
              through the  history  as  necessary.   This  is  an  incremental
              search.
       n\bno\bon\bn-\b-i\bin\bnc\bcr\bre\bem\bme\ben\bnt\bta\bal\bl-\b-r\bre\bev\bve\ber\brs\bse\be-\b-s\bse\bea\bar\brc\bch\bh-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(M\bM-\b-p\bp)\b)
              Search backward through the history starting at the current line
              using a non-incremental search for  a  string  supplied  by  the
              user.
       n\bno\bon\bn-\b-i\bin\bnc\bcr\bre\bem\bme\ben\bnt\bta\bal\bl-\b-f\bfo\bor\brw\bwa\bar\brd\bd-\b-s\bse\bea\bar\brc\bch\bh-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(M\bM-\b-n\bn)\b)
              Search  forward  through  the  history  using  a non-incremental
              search for a string supplied by the user.
       h\bhi\bis\bst\bto\bor\bry\by-\b-s\bse\bea\bar\brc\bch\bh-\b-f\bfo\bor\brw\bwa\bar\brd\bd
              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.
       h\bhi\bis\bst\bto\bor\bry\by-\b-s\bse\bea\bar\brc\bch\bh-\b-b\bba\bac\bck\bkw\bwa\bar\brd\bd
              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.
       y\bya\ban\bnk\bk-\b-n\bnt\bth\bh-\b-a\bar\brg\bg (\b(M\bM-\b-C\bC-\b-y\by)\b)
              Insert the first argument to the previous command  (usually  the
              second word on the previous line) at point.  With an argument _\bn,
              insert the _\bnth word from the previous command (the words in  the
              previous  command  begin  with  word  0).   A  negative argument
              inserts the _\bnth word from the end of the previous command.
       y\bya\ban\bnk\bk-\b-l\bla\bas\bst\bt-\b-a\bar\brg\bg (\b(M\bM-\b-.\b.,\b, M\bM-\b-_\b_)\b)
              Insert the last argument to the previous command (the last  word
              of  the  previous  history  entry).   With  an  argument, behave
              exactly like y\bya\ban\bnk\bk-\b-n\bnt\bth\bh-\b-a\bar\brg\bg.  Successive  calls  to  y\bya\ban\bnk\bk-\b-l\bla\bas\bst\bt-\b-a\bar\brg\bg
              move  back through the history list, inserting the last argument
              of each line in turn.
       s\bsh\bhe\bel\bll\bl-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-l\bli\bin\bne\be (\b(M\bM-\b-C\bC-\b-e\be)\b)
              Expand the line as the shell does.  This performs alias and his-
              tory expansion as well as all of the shell word expansions.  See
              H\bHI\bIS\bST\bTO\bOR\bRY\bY E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below for a description of history  expansion.
       h\bhi\bis\bst\bto\bor\bry\by-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-l\bli\bin\bne\be (\b(M\bM-\b-^\b^)\b)
              Perform  history  expansion  on  the  current line.  See H\bHI\bIS\bST\bTO\bOR\bRY\bY
              E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below for a description of history expansion.
       m\bma\bag\bgi\bic\bc-\b-s\bsp\bpa\bac\bce\be
              Perform history expansion on  the  current  line  and  insert  a
              space.  See H\bHI\bIS\bST\bTO\bOR\bRY\bY E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below for a description of history
              expansion.
       a\bal\bli\bia\bas\bs-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-l\bli\bin\bne\be
              Perform alias expansion on the current line.  See A\bAL\bLI\bIA\bAS\bSE\bES\bS  above
              for a description of alias expansion.
       h\bhi\bis\bst\bto\bor\bry\by-\b-a\ban\bnd\bd-\b-a\bal\bli\bia\bas\bs-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-l\bli\bin\bne\be
              Perform history and alias expansion on the current line.
       i\bin\bns\bse\ber\brt\bt-\b-l\bla\bas\bst\bt-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt (\b(M\bM-\b-.\b.,\b, M\bM-\b-_\b_)\b)
              A synonym for y\bya\ban\bnk\bk-\b-l\bla\bas\bst\bt-\b-a\bar\brg\bg.
       o\bop\bpe\ber\bra\bat\bte\be-\b-a\ban\bnd\bd-\b-g\bge\bet\bt-\b-n\bne\bex\bxt\bt (\b(C\bC-\b-o\bo)\b)
              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.
       e\bed\bdi\bit\bt-\b-a\ban\bnd\bd-\b-e\bex\bxe\bec\bcu\but\bte\be-\b-c\bco\bom\bmm\bma\ban\bnd\bd (\b(C\bC-\b-x\bxC\bC-\b-e\be)\b)
              Invoke  an  editor  on the current command line, and execute the
              result as shell commands.   B\bBa\bas\bsh\bh  attempts  to  invoke  $\b$F\bFC\bCE\bED\bDI\bIT\bT,
              $\b$E\bED\bDI\bIT\bTO\bOR\bR, and _\be_\bm_\ba_\bc_\bs as the editor, in that order.

   C\bCo\bom\bmm\bma\ban\bnd\bds\bs f\bfo\bor\br C\bCh\bha\ban\bng\bgi\bin\bng\bg T\bTe\bex\bxt\bt
       d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br (\b(C\bC-\b-d\bd)\b)
              Delete  the character at point.  If point is at the beginning of
              the line, there are no characters in  the  line,  and  the  last
              character typed was not bound to d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br, then return E\bEO\bOF\bF.
       b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br (\b(R\bRu\bub\bbo\bou\but\bt)\b)
              Delete  the  character  behind the cursor.  When given a numeric
              argument, save the deleted text on the kill ring.
       f\bfo\bor\brw\bwa\bar\brd\bd-\b-b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br
              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.
       q\bqu\buo\bot\bte\bed\bd-\b-i\bin\bns\bse\ber\brt\bt (\b(C\bC-\b-q\bq,\b, C\bC-\b-v\bv)\b)
              Add the next character typed to the line verbatim.  This is  how
              to insert characters like C\bC-\b-q\bq, for example.
       t\bta\bab\bb-\b-i\bin\bns\bse\ber\brt\bt (\b(C\bC-\b-v\bv T\bTA\bAB\bB)\b)
              Insert a tab character.
       s\bse\bel\blf\bf-\b-i\bin\bns\bse\ber\brt\bt (\b(a\ba,\b, b\bb,\b, A\bA,\b, 1\b1,\b, !\b!,\b, .\b..\b..\b.)\b)
              Insert the character typed.
       t\btr\bra\ban\bns\bsp\bpo\bos\bse\be-\b-c\bch\bha\bar\brs\bs (\b(C\bC-\b-t\bt)\b)
              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.
       t\btr\bra\ban\bns\bsp\bpo\bos\bse\be-\b-w\bwo\bor\brd\bds\bs (\b(M\bM-\b-t\bt)\b)
              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.
       u\bup\bpc\bca\bas\bse\be-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-u\bu)\b)
              Uppercase the current (or  following)  word.   With  a  negative
              argument, uppercase the previous word, but do not move point.
       d\bdo\bow\bwn\bnc\bca\bas\bse\be-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-l\bl)\b)
              Lowercase  the  current  (or  following)  word.  With a negative
              argument, lowercase the previous word, but do not move point.
       c\bca\bap\bpi\bit\bta\bal\bli\biz\bze\be-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-c\bc)\b)
              Capitalize the current (or following)  word.   With  a  negative
              argument, capitalize the previous word, but do not move point.
       o\bov\bve\ber\brw\bwr\bri\bit\bte\be-\b-m\bmo\bod\bde\be
              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 e\bem\bma\bac\bcs\bs mode; v\bvi\bi mode does overwrite differently.  Each  call
              to _\br_\be_\ba_\bd_\bl_\bi_\bn_\be_\b(_\b) starts in insert mode.  In overwrite mode, charac-
              ters bound to s\bse\bel\blf\bf-\b-i\bin\bns\bse\ber\brt\bt replace the text at point rather  than
              pushing  the  text  to  the  right.   Characters  bound to b\bba\bac\bck\bk-\b-
              w\bwa\bar\brd\bd-\b-d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br replace  the  character  before  point  with  a
              space.  By default, this command is unbound.

   K\bKi\bil\bll\bli\bin\bng\bg a\ban\bnd\bd Y\bYa\ban\bnk\bki\bin\bng\bg
       k\bki\bil\bll\bl-\b-l\bli\bin\bne\be (\b(C\bC-\b-k\bk)\b)
              Kill the text from point to the end of the line.
       b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-k\bki\bil\bll\bl-\b-l\bli\bin\bne\be (\b(C\bC-\b-x\bx R\bRu\bub\bbo\bou\but\bt)\b)
              Kill backward to the beginning of the line.
       u\bun\bni\bix\bx-\b-l\bli\bin\bne\be-\b-d\bdi\bis\bsc\bca\bar\brd\bd (\b(C\bC-\b-u\bu)\b)
              Kill  backward  from  point  to  the beginning of the line.  The
              killed text is saved on the kill-ring.
       k\bki\bil\bll\bl-\b-w\bwh\bho\bol\ble\be-\b-l\bli\bin\bne\be
              Kill all characters on the current line, no matter  where  point
              is.
       k\bki\bil\bll\bl-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-d\bd)\b)
              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 f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd.
       b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-k\bki\bil\bll\bl-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-R\bRu\bub\bbo\bou\but\bt)\b)
              Kill  the  word  behind  point.  Word boundaries are the same as
              those used by b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd.
       u\bun\bni\bix\bx-\b-w\bwo\bor\brd\bd-\b-r\bru\bub\bbo\bou\but\bt (\b(C\bC-\b-w\bw)\b)
              Kill the word behind point, using white space as a  word  bound-
              ary.  The killed text is saved on the kill-ring.
       u\bun\bni\bix\bx-\b-f\bfi\bil\ble\ben\bna\bam\bme\be-\b-r\bru\bub\bbo\bou\but\bt
              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.
       d\bde\bel\ble\bet\bte\be-\b-h\bho\bor\bri\biz\bzo\bon\bnt\bta\bal\bl-\b-s\bsp\bpa\bac\bce\be (\b(M\bM-\b-\\b\)\b)
              Delete all spaces and tabs around point.
       k\bki\bil\bll\bl-\b-r\bre\beg\bgi\bio\bon\bn
              Kill the text in the current region.
       c\bco\bop\bpy\by-\b-r\bre\beg\bgi\bio\bon\bn-\b-a\bas\bs-\b-k\bki\bil\bll\bl
              Copy the text in the region to the kill buffer.
       c\bco\bop\bpy\by-\b-b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd
              Copy  the word before point to the kill buffer.  The word bound-
              aries are the same as b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd.
       c\bco\bop\bpy\by-\b-f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd
              Copy the word following point to  the  kill  buffer.   The  word
              boundaries are the same as f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd.
       y\bya\ban\bnk\bk (\b(C\bC-\b-y\by)\b)
              Yank the top of the kill ring into the buffer at point.
       y\bya\ban\bnk\bk-\b-p\bpo\bop\bp (\b(M\bM-\b-y\by)\b)
              Rotate  the kill ring, and yank the new top.  Only works follow-
              ing y\bya\ban\bnk\bk or y\bya\ban\bnk\bk-\b-p\bpo\bop\bp.

   N\bNu\bum\bme\ber\bri\bic\bc A\bAr\brg\bgu\bum\bme\ben\bnt\bts\bs
       d\bdi\big\bgi\bit\bt-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt (\b(M\bM-\b-0\b0,\b, M\bM-\b-1\b1,\b, .\b..\b..\b.,\b, M\bM-\b--\b-)\b)
              Add this digit to the argument already accumulating, or start  a
              new argument.  M-- starts a negative argument.
       u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt
              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  u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt  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.

   C\bCo\bom\bmp\bpl\ble\bet\bti\bin\bng\bg
       c\bco\bom\bmp\bpl\ble\bet\bte\be (\b(T\bTA\bAB\bB)\b)
              Attempt  to  perform  completion on the text before point.  B\bBa\bas\bsh\bh
              attempts completion treating the text as a variable (if the text
              begins  with  $\b$), username (if the text begins with ~\b~), hostname
              (if the text begins with @\b@), or command (including  aliases  and
              functions) in turn.  If none of these produces a match, filename
              completion is attempted.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(M\bM-\b-?\b?)\b)
              List the possible completions of the text before point.
       i\bin\bns\bse\ber\brt\bt-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(M\bM-\b-*\b*)\b)
              Insert all completions of the text before point that would  have
              been generated by p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs.
       m\bme\ben\bnu\bu-\b-c\bco\bom\bmp\bpl\ble\bet\bte\be
              Similar  to c\bco\bom\bmp\bpl\ble\bet\bte\be, but replaces the word to be completed with
              a single match from the list of possible completions.   Repeated
              execution  of  m\bme\ben\bnu\bu-\b-c\bco\bom\bmp\bpl\ble\bet\bte\be  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
              b\bbe\bel\bll\bl-\b-s\bst\bty\byl\ble\be) and the original text is restored.  An argument of _\bn
              moves  _\bn  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  T\bTA\bAB\bB, but is unbound by
              default.
       d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br-\b-o\bor\br-\b-l\bli\bis\bst\bt
              Deletes the character under the cursor if not at  the  beginning
              or  end  of  the  line (like d\bde\bel\ble\bet\bte\be-\b-c\bch\bha\bar\br).  If at the end of the
              line, behaves identically to p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs.  This command
              is unbound by default.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-f\bfi\bil\ble\ben\bna\bam\bme\be (\b(M\bM-\b-/\b/)\b)
              Attempt filename completion on the text before point.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-f\bfi\bil\ble\ben\bna\bam\bme\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(C\bC-\b-x\bx /\b/)\b)
              List the possible completions of the text before point, treating
              it as a filename.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-u\bus\bse\ber\brn\bna\bam\bme\be (\b(M\bM-\b-~\b~)\b)
              Attempt completion on the text before point, treating  it  as  a
              username.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-u\bus\bse\ber\brn\bna\bam\bme\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(C\bC-\b-x\bx ~\b~)\b)
              List the possible completions of the text before point, treating
              it as a username.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-v\bva\bar\bri\bia\bab\bbl\ble\be (\b(M\bM-\b-$\b$)\b)
              Attempt completion on the text before point, treating  it  as  a
              shell variable.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-v\bva\bar\bri\bia\bab\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(C\bC-\b-x\bx $\b$)\b)
              List the possible completions of the text before point, treating
              it as a shell variable.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-h\bho\bos\bst\btn\bna\bam\bme\be (\b(M\bM-\b-@\b@)\b)
              Attempt completion on the text before point, treating  it  as  a
              hostname.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-h\bho\bos\bst\btn\bna\bam\bme\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(C\bC-\b-x\bx @\b@)\b)
              List the possible completions of the text before point, treating
              it as a hostname.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-c\bco\bom\bmm\bma\ban\bnd\bd (\b(M\bM-\b-!\b!)\b)
              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.
       p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmm\bma\ban\bnd\bd-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bns\bs (\b(C\bC-\b-x\bx !\b!)\b)
              List the possible completions of the text before point, treating
              it as a command name.
       d\bdy\byn\bna\bam\bmi\bic\bc-\b-c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-h\bhi\bis\bst\bto\bor\bry\by (\b(M\bM-\b-T\bTA\bAB\bB)\b)
              Attempt completion on the text before point, comparing the  text
              against  lines  from  the  history  list for possible completion
              matches.
       c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-i\bin\bnt\bto\bo-\b-b\bbr\bra\bac\bce\bes\bs (\b(M\bM-\b-{\b{)\b)
              Perform filename completion and insert the list of possible com-
              pletions  enclosed within braces so the list is available to the
              shell (see B\bBr\bra\bac\bce\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn above).

   K\bKe\bey\byb\bbo\boa\bar\brd\bd M\bMa\bac\bcr\bro\bos\bs
       s\bst\bta\bar\brt\bt-\b-k\bkb\bbd\bd-\b-m\bma\bac\bcr\bro\bo (\b(C\bC-\b-x\bx (\b()\b)
              Begin saving the characters  typed  into  the  current  keyboard
              macro.
       e\ben\bnd\bd-\b-k\bkb\bbd\bd-\b-m\bma\bac\bcr\bro\bo (\b(C\bC-\b-x\bx )\b))\b)
              Stop saving the characters typed into the current keyboard macro
              and store the definition.
       c\bca\bal\bll\bl-\b-l\bla\bas\bst\bt-\b-k\bkb\bbd\bd-\b-m\bma\bac\bcr\bro\bo (\b(C\bC-\b-x\bx e\be)\b)
              Re-execute the last keyboard macro defined, by making the  char-
              acters in the macro appear as if typed at the keyboard.

   M\bMi\bis\bsc\bce\bel\bll\bla\ban\bne\beo\bou\bus\bs
       r\bre\be-\b-r\bre\bea\bad\bd-\b-i\bin\bni\bit\bt-\b-f\bfi\bil\ble\be (\b(C\bC-\b-x\bx C\bC-\b-r\br)\b)
              Read  in  the  contents of the _\bi_\bn_\bp_\bu_\bt_\br_\bc file, and incorporate any
              bindings or variable assignments found there.
       a\bab\bbo\bor\brt\bt (\b(C\bC-\b-g\bg)\b)
              Abort the current editing command and ring the  terminal's  bell
              (subject to the setting of b\bbe\bel\bll\bl-\b-s\bst\bty\byl\ble\be).
       d\bdo\bo-\b-u\bup\bpp\bpe\ber\brc\bca\bas\bse\be-\b-v\bve\ber\brs\bsi\bio\bon\bn (\b(M\bM-\b-a\ba,\b, M\bM-\b-b\bb,\b, M\bM-\b-_\bx,\b, .\b..\b..\b.)\b)
              If  the  metafied character _\bx is lowercase, run the command that
              is bound to the corresponding uppercase character.
       p\bpr\bre\bef\bfi\bix\bx-\b-m\bme\bet\bta\ba (\b(E\bES\bSC\bC)\b)
              Metafy the next character typed.  E\bES\bSC\bC f\bf is equivalent to M\bMe\bet\bta\ba-\b-f\bf.
       u\bun\bnd\bdo\bo (\b(C\bC-\b-_\b_,\b, C\bC-\b-x\bx C\bC-\b-u\bu)\b)
              Incremental undo, separately remembered for each line.
       r\bre\bev\bve\ber\brt\bt-\b-l\bli\bin\bne\be (\b(M\bM-\b-r\br)\b)
              Undo  all changes made to this line.  This is like executing the
              u\bun\bnd\bdo\bo command enough times to return  the  line  to  its  initial
              state.
       t\bti\bil\bld\bde\be-\b-e\bex\bxp\bpa\ban\bnd\bd (\b(M\bM-\b-&\b&)\b)
              Perform tilde expansion on the current word.
       s\bse\bet\bt-\b-m\bma\bar\brk\bk (\b(C\bC-\b-@\b@,\b, M\bM-\b-<\b<s\bsp\bpa\bac\bce\be>\b>)\b)
              Set  the  mark to the point.  If a numeric argument is supplied,
              the mark is set to that position.
       e\bex\bxc\bch\bha\ban\bng\bge\be-\b-p\bpo\boi\bin\bnt\bt-\b-a\ban\bnd\bd-\b-m\bma\bar\brk\bk (\b(C\bC-\b-x\bx C\bC-\b-x\bx)\b)
              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.
       c\bch\bha\bar\bra\bac\bct\bte\ber\br-\b-s\bse\bea\bar\brc\bch\bh (\b(C\bC-\b-]\b])\b)
              A character is read and point is moved to the next occurrence of
              that  character.   A negative count searches for previous occur-
              rences.
       c\bch\bha\bar\bra\bac\bct\bte\ber\br-\b-s\bse\bea\bar\brc\bch\bh-\b-b\bba\bac\bck\bkw\bwa\bar\brd\bd (\b(M\bM-\b-C\bC-\b-]\b])\b)
              A character is read and point is moved to  the  previous  occur-
              rence  of  that character.  A negative count searches for subse-
              quent occurrences.
       i\bin\bns\bse\ber\brt\bt-\b-c\bco\bom\bmm\bme\ben\bnt\bt (\b(M\bM-\b-#\b#)\b)
              Without a numeric argument,  the  value  of  the  readline  c\bco\bom\bm-\b-
              m\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn  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 c\bco\bom\bmm\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn, the value is inserted,  other-
              wise the characters in c\bco\bom\bmm\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn 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 c\bco\bom\bmm\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn
              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.
       g\bgl\blo\bob\bb-\b-c\bco\bom\bmp\bpl\ble\bet\bte\be-\b-w\bwo\bor\brd\bd (\b(M\bM-\b-g\bg)\b)
              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 file names  for  possible
              completions.
       g\bgl\blo\bob\bb-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-w\bwo\bor\brd\bd (\b(C\bC-\b-x\bx *\b*)\b)
              The  word  before  point  is  treated  as a pattern for pathname
              expansion, and the list of  matching  file  names  is  inserted,
              replacing  the  word.   If  a  numeric  argument is supplied, an
              asterisk is appended before pathname expansion.
       g\bgl\blo\bob\bb-\b-l\bli\bis\bst\bt-\b-e\bex\bxp\bpa\ban\bns\bsi\bio\bon\bns\bs (\b(C\bC-\b-x\bx g\bg)\b)
              The list  of  expansions  that  would  have  been  generated  by
              g\bgl\blo\bob\bb-\b-e\bex\bxp\bpa\ban\bnd\bd-\b-w\bwo\bor\brd\bd  is  displayed,  and the line is redrawn.  If a
              numeric argument is supplied, an  asterisk  is  appended  before
              pathname expansion.
       d\bdu\bum\bmp\bp-\b-f\bfu\bun\bnc\bct\bti\bio\bon\bns\bs
              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
              _\bi_\bn_\bp_\bu_\bt_\br_\bc file.
       d\bdu\bum\bmp\bp-\b-v\bva\bar\bri\bia\bab\bbl\ble\bes\bs
              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 _\bi_\bn_\bp_\bu_\bt_\br_\bc file.
       d\bdu\bum\bmp\bp-\b-m\bma\bac\bcr\bro\bos\bs
              Print  all of the readline key sequences bound to macros and the
              strings they ouput.  If a numeric argument is supplied, the out-
              put  is  formatted  in such a way that it can be made part of an
              _\bi_\bn_\bp_\bu_\bt_\br_\bc file.
       d\bdi\bis\bsp\bpl\bla\bay\by-\b-s\bsh\bhe\bel\bll\bl-\b-v\bve\ber\brs\bsi\bio\bon\bn (\b(C\bC-\b-x\bx C\bC-\b-v\bv)\b)
              Display version information about the current instance of  b\bba\bas\bsh\bh.

   P\bPr\bro\bog\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn
       When  word  completion  is  attempted  for an argument to a command for
       which a completion specification (a _\bc_\bo_\bm_\bp_\bs_\bp_\be_\bc) has  been  defined  using
       the  c\bco\bom\bmp\bpl\ble\bet\bte\be  builtin  (see  S\bSH\bHE\bEL\bLL\bL  B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below), the pro-
       grammable completion facilities are invoked.

       First, the command name is identified.  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.

       Once  a  compspec  has  been  found, it is used to generate the list of
       matching words.  If a compspec is not found, the default  b\bba\bas\bsh\bh  comple-
       tion as described above under C\bCo\bom\bmp\bpl\ble\bet\bti\bin\bng\bg 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
       -\b-f\bf  or -\b-d\bd option is used for filename or directory name completion, the
       shell variable F\bFI\bIG\bGN\bNO\bOR\bRE\bE is used to filter the matches.

       Any completions specified by a filename expansion  pattern  to  the  -\b-G\bG
       option are generated next.  The words generated by the pattern need not
       match the word being completed.  The G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE shell variable  is  not
       used to filter the matches, but the F\bFI\bIG\bGN\bNO\bOR\bRE\bE variable is used.

       Next,  the string specified as the argument to the -\b-W\bW option is consid-
       ered.  The string is first split using the characters in the  I\bIF\bFS\bS  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,  arithmetic expansion, and
       pathname expansion, as described above under  E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN.   The  results
       are  split  using  the rules described above under W\bWo\bor\brd\bd S\bSp\bpl\bli\bit\btt\bti\bin\bng\bg.  The
       results of the expansion are prefix-matched against the word being com-
       pleted, and the matching words become the possible completions.

       After  these matches have been generated, any shell function or command
       specified with the -\b-F\bF and -\b-C\bC options is invoked.  When the  command  or
       function  is  invoked,  the  C\bCO\bOM\bMP\bP_\b_L\bLI\bIN\bNE\bE  and  C\bCO\bOM\bMP\bP_\b_P\bPO\bOI\bIN\bNT\bT  variables  are
       assigned values as described above under S\bSh\bhe\bel\bll\bl V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs.  If  a  shell
       function  is being invoked, the C\bCO\bOM\bMP\bP_\b_W\bWO\bOR\bRD\bDS\bS and C\bCO\bOM\bMP\bP_\b_C\bCW\bWO\bOR\bRD\bD variables are
       also set.  When the function or command is invoked, the first  argument
       is  the  name  of  the command whose arguments are being completed, the
       second argument is the word being completed, and the third argument  is
       the  word  preceding  the  word  being completed on the current command
       line.  No filtering of the generated completions against the word being
       completed is performed; the function or command has complete freedom in
       generating the matches.

       Any function specified with -\b-F\bF is invoked first.  The function may  use
       any  of  the  shell facilities, including the c\bco\bom\bmp\bpg\bge\ben\bn builtin described
       below, to generate the matches.  It must put the  possible  completions
       in the C\bCO\bOM\bMP\bPR\bRE\bEP\bPL\bLY\bY array variable.

       Next,  any  command specified with the -\b-C\bC 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 -\b-X\bX option is applied to the list.  The filter is a pat-
       tern as used for pathname expansion; a &\b& in  the  pattern  is  replaced
       with  the text of the word being completed.  A literal &\b& 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 !\b! negates the pattern; in this case any completion not match-
       ing the pattern will be removed.

       Finally, any prefix and suffix specified with the -\b-P\bP and -\b-S\bS 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
       -\b-o\bo d\bdi\bir\brn\bna\bam\bme\bes\bs option was supplied  to  c\bco\bom\bmp\bpl\ble\bet\bte\be  when  the  compspec  was
       defined, directory name completion is attempted.

       If  the  -\b-o\bo  p\bpl\blu\bus\bsd\bdi\bir\brs\bs option was supplied to c\bco\bom\bmp\bpl\ble\bet\bte\be 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 b\bba\bas\bsh\bh completions are not attempted, and the readline default of
       filename completion is disabled.  If the -\b-o\bo b\bba\bas\bsh\bhd\bde\bef\bfa\bau\bul\blt\bt option was sup-
       plied  to c\bco\bom\bmp\bpl\ble\bet\bte\be when the compspec was defined, the b\bba\bas\bsh\bh default com-
       pletions are attempted if the compspec generates no matches.  If the -\b-o\bo
       d\bde\bef\bfa\bau\bul\blt\bt  option was supplied to c\bco\bom\bmp\bpl\ble\bet\bte\be when the compspec was defined,
       readline's default completion will be performed if the  compspec  (and,
       if attempted, the default b\bba\bas\bsh\bh 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 m\bma\bar\brk\bk-\b-d\bdi\bir\bre\bec\bct\bto\bor\bri\bie\bes\bs readline variable, regardless of  the
       setting of the m\bma\bar\brk\bk-\b-s\bsy\bym\bml\bli\bin\bnk\bke\bed\bd-\b-d\bdi\bir\bre\bec\bct\bto\bor\bri\bie\bes\bs readline variable.

H\bHI\bIS\bST\bTO\bOR\bRY\bY
       When  the  -\b-o\bo  h\bhi\bis\bst\bto\bor\bry\by  option to the s\bse\bet\bt builtin is enabled, the shell
       provides access to the _\bc_\bo_\bm_\bm_\ba_\bn_\bd _\bh_\bi_\bs_\bt_\bo_\br_\by, the list of commands previously
       typed.   The  value  of  the H\bHI\bIS\bST\bTS\bSI\bIZ\bZE\bE variable is used as the number of
       commands to save in a history list.  The text of the last H\bHI\bIS\bST\bTS\bSI\bIZ\bZE\bE com-
       mands  (default  500)  is  saved.  The shell stores each command in the
       history list prior to parameter and variable expansion  (see  E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
       above)  but after history expansion is performed, subject to the values
       of the shell variables H\bHI\bIS\bST\bTI\bIG\bGN\bNO\bOR\bRE\bE and H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL.

       On startup, the history is initialized from the file named by the vari-
       able  H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE  (default _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bh_\bi_\bs_\bt_\bo_\br_\by).  The file named by the value
       of H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE is truncated, if necessary, to contain  no  more  than  the
       number of lines specified by the value of H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bES\bSI\bIZ\bZE\bE.  When an inter-
       active shell exits, the last $\b$H\bHI\bIS\bST\bTS\bSI\bIZ\bZE\bE lines are copied from  the  his-
       tory list to $\b$H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE.  If the h\bhi\bis\bst\bta\bap\bpp\bpe\ben\bnd\bd shell option is enabled (see
       the description of s\bsh\bho\bop\bpt\bt under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below), the lines
       are  appended  to the history file, otherwise the history file is over-
       written.  If H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE is unset, or if the history file  is  unwritable,
       the  history  is not saved.  After saving the history, the history file
       is truncated to contain no more than H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bES\bSI\bIZ\bZE\bE lines.  If  H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE-\b-
       S\bSI\bIZ\bZE\bE is not set, no truncation is performed.

       The  builtin  command f\bfc\bc (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below) may be used
       to list or edit and re-execute a portion of the history list.  The h\bhi\bis\bs-\b-
       t\bto\bor\bry\by  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 H\bHI\bIS\bST\bTC\bCO\bON\bNT\bTR\bRO\bOL\bL and H\bHI\bIS\bST\bTI\bIG\bGN\bNO\bOR\bRE\bE variables may be set to cause the
       shell to save only a subset of the commands entered.  The c\bcm\bmd\bdh\bhi\bis\bst\bt 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 l\bli\bit\bth\bhi\bis\bst\bt shell option
       causes the shell to save the command with embedded newlines instead  of
       semicolons.  See the description of the s\bsh\bho\bop\bpt\bt builtin below under S\bSH\bHE\bEL\bLL\bL
       B\bBU\bUI\bIL\bLT\bTI\bIN\bN  C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS  for  information  on  setting  and  unsetting  shell
       options.

H\bHI\bIS\bST\bTO\bOR\bRY\bY E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
       The  shell  supports a history expansion feature that is similar to the
       history expansion in c\bcs\bsh\bh.\b.  This section describes what syntax  features
       are  available.   This  feature  is  enabled by default for interactive
       shells, and can be disabled using the +\b+H\bH option to the s\bse\bet\bt builtin com-
       mand (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS 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 _\be_\bv_\be_\bn_\bt, and the portions of that line that  are  acted  upon  are
       _\bw_\bo_\br_\bd_\bs.   Various  _\bm_\bo_\bd_\bi_\bf_\bi_\be_\br_\bs  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 _\bm_\be_\bt_\ba_\bc_\bh_\ba_\br_\ba_\bc_\bt_\be_\br-separated words surrounded by
       quotes are considered one word.  History expansions are  introduced  by
       the  appearance  of  the  history  expansion  character,  which is !\b! by
       default.  Only backslash (\\b\) 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 =\b=.  If the e\bex\bxt\btg\bgl\blo\bob\bb shell option is
       enabled, (\b( will also inhibit expansion.

       Several shell options settable with the s\bsh\bho\bop\bpt\bt builtin may  be  used  to
       tailor  the  behavior  of  history  expansion.  If the h\bhi\bis\bst\btv\bve\ber\bri\bif\bfy\by shell
       option is enabled (see the description of the s\bsh\bho\bop\bpt\bt builtin), and r\bre\bea\bad\bd-\b-
       l\bli\bin\bne\be is being used, history substitutions are not immediately passed to
       the shell parser.  Instead, the expanded  line  is  reloaded  into  the
       r\bre\bea\bad\bdl\bli\bin\bne\be editing buffer for further modification.  If r\bre\bea\bad\bdl\bli\bin\bne\be is being
       used, and the h\bhi\bis\bst\btr\bre\bee\bed\bdi\bit\bt shell option is enabled, a failed history sub-
       stitution will be reloaded into the r\bre\bea\bad\bdl\bli\bin\bne\be editing buffer for correc-
       tion.  The -\b-p\bp option to the h\bhi\bis\bst\bto\bor\bry\by builtin command may be used to  see
       what a history expansion will do before using it.  The -\b-s\bs option to the
       h\bhi\bis\bst\bto\bor\bry\by 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 h\bhi\bis\bst\btc\bch\bha\bar\brs\bs above under S\bSh\bhe\bel\bll\bl
       V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs).

   E\bEv\bve\ben\bnt\bt D\bDe\bes\bsi\big\bgn\bna\bat\bto\bor\brs\bs
       An event designator is a reference to a command line entry in the  his-
       tory list.

       !\b!      Start  a  history substitution, except when followed by a b\bbl\bla\ban\bnk\bk,
              newline, carriage return, = or ( (when the e\bex\bxt\btg\bgl\blo\bob\bb shell  option
              is enabled using the s\bsh\bho\bop\bpt\bt builtin).
       !\b!_\bn     Refer to command line _\bn.
       !\b!-\b-_\bn    Refer to the current command line minus _\bn.
       !\b!!\b!     Refer to the previous command.  This is a synonym for `!-1'.
       !\b!_\bs_\bt_\br_\bi_\bn_\bg
              Refer to the most recent command starting with _\bs_\bt_\br_\bi_\bn_\bg.
       !\b!?\b?_\bs_\bt_\br_\bi_\bn_\bg[\b[?\b?]\b]
              Refer  to the most recent command containing _\bs_\bt_\br_\bi_\bn_\bg.  The trail-
              ing ?\b? may be omitted if _\bs_\bt_\br_\bi_\bn_\bg is followed immediately by a new-
              line.
       ^\b^_\bs_\bt_\br_\bi_\bn_\bg_\b1^\b^_\bs_\bt_\br_\bi_\bn_\bg_\b2^\b^
              Quick  substitution.  Repeat the last command, replacing _\bs_\bt_\br_\bi_\bn_\bg_\b1
              with _\bs_\bt_\br_\bi_\bn_\bg_\b2.  Equivalent to ``!!:s/_\bs_\bt_\br_\bi_\bn_\bg_\b1/_\bs_\bt_\br_\bi_\bn_\bg_\b2/'' (see M\bMo\bod\bd-\b-
              i\bif\bfi\bie\ber\brs\bs below).
       !\b!#\b#     The entire command line typed so far.

   W\bWo\bor\brd\bd D\bDe\bes\bsi\big\bgn\bna\bat\bto\bor\brs\bs
       Word  designators are used to select desired words from the event.  A :\b:
       separates the event specification from the word designator.  It may  be
       omitted  if  the word designator begins with a ^\b^, $\b$, *\b*, -\b-, or %\b%.  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.

       0\b0 (\b(z\bze\ber\bro\bo)\b)
              The zeroth word.  For the shell, this is the command word.
       _\bn      The _\bnth word.
       ^\b^      The first argument.  That is, word 1.
       $\b$      The last argument.
       %\b%      The word matched by the most recent `?_\bs_\bt_\br_\bi_\bn_\bg?' search.
       _\bx-\b-_\by    A range of words; `-_\by' abbreviates `0-_\by'.
       *\b*      All of the words but the zeroth.  This is a synonym  for  `_\b1_\b-_\b$'.
              It  is  not  an  error to use *\b* if there is just one word in the
              event; the empty string is returned in that case.
       x\bx*\b*     Abbreviates _\bx_\b-_\b$.
       x\bx-\b-     Abbreviates _\bx_\b-_\b$ like x\bx*\b*, but omits the last word.

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

   M\bMo\bod\bdi\bif\bfi\bie\ber\brs\bs
       After  the optional word designator, there may appear a sequence of one
       or more of the following modifiers, each preceded by a `:'.

       h\bh      Remove a trailing file name component, leaving only the head.
       t\bt      Remove all leading file name components, leaving the tail.
       r\br      Remove a trailing suffix of the form _\b._\bx_\bx_\bx, leaving the basename.
       e\be      Remove all but the trailing suffix.
       p\bp      Print the new command but do not execute it.
       q\bq      Quote the substituted words, escaping further substitutions.
       x\bx      Quote  the  substituted words as with q\bq, but break into words at
              b\bbl\bla\ban\bnk\bks\bs and newlines.
       s\bs/\b/_\bo_\bl_\bd/\b/_\bn_\be_\bw/\b/
              Substitute _\bn_\be_\bw for the first occurrence  of  _\bo_\bl_\bd  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 _\bo_\bl_\bd and _\bn_\be_\bw with a single
              backslash.  If & appears in _\bn_\be_\bw, it is replaced by _\bo_\bl_\bd.  A  sin-
              gle  backslash  will  quote the &.  If _\bo_\bl_\bd is null, it is set to
              the last _\bo_\bl_\bd substituted, or, if no previous  history  substitu-
              tions took place, the last _\bs_\bt_\br_\bi_\bn_\bg in a !\b!?\b?_\bs_\bt_\br_\bi_\bn_\bg[\b[?\b?]\b]  search.
       &\b&      Repeat the previous substitution.
       g\bg      Cause changes to be applied over the entire event line.  This is
              used in conjunction with `:\b:s\bs' (e.g.,  `:\b:g\bgs\bs/\b/_\bo_\bl_\bd/\b/_\bn_\be_\bw/\b/')  or  `:\b:&\b&'.
              If  used with `:\b:s\bs', 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 a\ba may be used as a synonym for g\bg.
       G\bG      Apply  the following `s\bs' modifier once to each word in the event
              line.

S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by -\b- accepts -\b--\b- to signify the end of the
       options.
       :\b: [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]
              No effect; the command does nothing beyond  expanding  _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs
              and  performing any specified redirections.  A zero exit code is
              returned.

        .\b.  _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]
       s\bso\bou\bur\brc\bce\be _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]
              Read and execute commands from _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be  in  the  current  shell
              environment  and  return  the  exit  status  of the last command
              executed from _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be.  If _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be does not contain  a  slash,
              file  names  in  P\bPA\bAT\bTH\bH  are used to find the directory containing
              _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be.  The file searched for in P\bPA\bAT\bTH\bH need not be executable.
              When  b\bba\bas\bsh\bh  is  not  in  _\bp_\bo_\bs_\bi_\bx  _\bm_\bo_\bd_\be,  the  current directory is
              searched if no file is found in P\bPA\bAT\bTH\bH.  If the s\bso\bou\bur\brc\bce\bep\bpa\bat\bth\bh  option
              to  the  s\bsh\bho\bop\bpt\bt  builtin  command  is turned off, the P\bPA\bAT\bTH\bH is not
              searched.  If any _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs are supplied, they become the  posi-
              tional  parameters  when  _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be  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 _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be is  not  found  or
              cannot be read.

       a\bal\bli\bia\bas\bs [-\b-p\bp] [_\bn_\ba_\bm_\be[=_\bv_\ba_\bl_\bu_\be] ...]
              A\bAl\bli\bia\bas\bs with no arguments or with the -\b-p\bp option prints the list of
              aliases in the form a\bal\bli\bia\bas\bs _\bn_\ba_\bm_\be=_\bv_\ba_\bl_\bu_\be on standard  output.   When
              arguments  are supplied, an alias is defined for each _\bn_\ba_\bm_\be whose
              _\bv_\ba_\bl_\bu_\be is given.  A trailing space in  _\bv_\ba_\bl_\bu_\be causes the next word
              to be checked for alias substitution when the alias is expanded.
              For each _\bn_\ba_\bm_\be in the argument list for which no  _\bv_\ba_\bl_\bu_\be  is  sup-
              plied,  the  name  and  value  of  the  alias is printed.  A\bAl\bli\bia\bas\bs
              returns true unless a _\bn_\ba_\bm_\be is given for which no alias has  been
              defined.

       b\bbg\bg [_\bj_\bo_\bb_\bs_\bp_\be_\bc ...]
              Resume  each  suspended  job _\bj_\bo_\bb_\bs_\bp_\be_\bc in the background, as if it
              had been started with &\b&.  If _\bj_\bo_\bb_\bs_\bp_\be_\bc is not present, the shell's
              notion  of the _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb is used.  b\bbg\bg _\bj_\bo_\bb_\bs_\bp_\be_\bc returns 0 unless
              run when job control is disabled or, when run with  job  control
              enabled,  if the last _\bj_\bo_\bb_\bs_\bp_\be_\bc was not found or was started with-
              out job control.

       b\bbi\bin\bnd\bd [-\b-m\bm _\bk_\be_\by_\bm_\ba_\bp] [-\b-l\blp\bps\bsv\bvP\bPS\bSV\bV]
       b\bbi\bin\bnd\bd [-\b-m\bm _\bk_\be_\by_\bm_\ba_\bp] [-\b-q\bq _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn] [-\b-u\bu _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn] [-\b-r\br _\bk_\be_\by_\bs_\be_\bq]
       b\bbi\bin\bnd\bd [-\b-m\bm _\bk_\be_\by_\bm_\ba_\bp] -\b-f\bf _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be
       b\bbi\bin\bnd\bd [-\b-m\bm _\bk_\be_\by_\bm_\ba_\bp] -\b-x\bx _\bk_\be_\by_\bs_\be_\bq:_\bs_\bh_\be_\bl_\bl_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd
       b\bbi\bin\bnd\bd [-\b-m\bm _\bk_\be_\by_\bm_\ba_\bp] _\bk_\be_\by_\bs_\be_\bq:_\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be
       b\bbi\bin\bnd\bd _\br_\be_\ba_\bd_\bl_\bi_\bn_\be_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd
              Display current r\bre\bea\bad\bdl\bli\bin\bne\be key and function bindings, bind  a  key
              sequence  to  a  r\bre\bea\bad\bdl\bli\bin\bne\be  function  or macro, or set a r\bre\bea\bad\bdl\bli\bin\bne\be
              variable.  Each non-option argument is a  command  as  it  would
              appear  in  _\b._\bi_\bn_\bp_\bu_\bt_\br_\bc, 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:
              -\b-m\bm _\bk_\be_\by_\bm_\ba_\bp
                     Use _\bk_\be_\by_\bm_\ba_\bp as the keymap to be affected by the subsequent
                     bindings.  Acceptable _\bk_\be_\by_\bm_\ba_\bp names are _\be_\bm_\ba_\bc_\bs_\b, _\be_\bm_\ba_\bc_\bs_\b-_\bs_\bt_\ba_\bn_\b-
                     _\bd_\ba_\br_\bd_\b,  _\be_\bm_\ba_\bc_\bs_\b-_\bm_\be_\bt_\ba_\b,  _\be_\bm_\ba_\bc_\bs_\b-_\bc_\bt_\bl_\bx_\b,  _\bv_\bi_\b, _\bv_\bi_\b-_\bm_\bo_\bv_\be_\b, _\bv_\bi_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd,
                     and _\bv_\bi_\b-_\bi_\bn_\bs_\be_\br_\bt.  _\bv_\bi is equivalent to _\bv_\bi_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd; _\be_\bm_\ba_\bc_\bs  is
                     equivalent to _\be_\bm_\ba_\bc_\bs_\b-_\bs_\bt_\ba_\bn_\bd_\ba_\br_\bd.
              -\b-l\bl     List the names of all r\bre\bea\bad\bdl\bli\bin\bne\be functions.
              -\b-p\bp     Display  r\bre\bea\bad\bdl\bli\bin\bne\be  function  names and bindings in such a
                     way that they can be re-read.
              -\b-P\bP     List current r\bre\bea\bad\bdl\bli\bin\bne\be function names and bindings.
              -\b-v\bv     Display r\bre\bea\bad\bdl\bli\bin\bne\be variable names and values in such a  way
                     that they can be re-read.
              -\b-V\bV     List current r\bre\bea\bad\bdl\bli\bin\bne\be variable names and values.
              -\b-s\bs     Display  r\bre\bea\bad\bdl\bli\bin\bne\be  key  sequences bound to macros and the
                     strings they output in such a way that they  can  be  re-
                     read.
              -\b-S\bS     Display  r\bre\bea\bad\bdl\bli\bin\bne\be  key  sequences bound to macros and the
                     strings they output.
              -\b-f\bf _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be
                     Read key bindings from _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be.
              -\b-q\bq _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn
                     Query about which keys invoke the named _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn.
              -\b-u\bu _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn
                     Unbind all keys bound to the named _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn.
              -\b-r\br _\bk_\be_\by_\bs_\be_\bq
                     Remove any current binding for _\bk_\be_\by_\bs_\be_\bq.
              -\b-x\bx _\bk_\be_\by_\bs_\be_\bq:\b:_\bs_\bh_\be_\bl_\bl_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd
                     Cause _\bs_\bh_\be_\bl_\bl_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd to be  executed  whenever  _\bk_\be_\by_\bs_\be_\bq  is
                     entered.

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

       b\bbr\bre\bea\bak\bk [_\bn]
              Exit from within a f\bfo\bor\br, w\bwh\bhi\bil\ble\be, u\bun\bnt\bti\bil\bl, or s\bse\bel\ble\bec\bct\bt loop.  If  _\bn  is
              specified,  break  _\bn  levels.   _\bn must be >= 1.  If _\bn is greater
              than the number of enclosing  loops,  all  enclosing  loops  are
              exited.  The return value is 0 unless the shell is not executing
              a loop when b\bbr\bre\bea\bak\bk is executed.

       b\bbu\bui\bil\blt\bti\bin\bn _\bs_\bh_\be_\bl_\bl_\b-_\bb_\bu_\bi_\bl_\bt_\bi_\bn [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]
              Execute the specified shell builtin, passing it  _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs,  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 c\bcd\bd builtin is
              commonly redefined this way.  The  return  status  is  false  if
              _\bs_\bh_\be_\bl_\bl_\b-_\bb_\bu_\bi_\bl_\bt_\bi_\bn is not a shell builtin command.

       c\bcd\bd [-\b-L\bL|\b|-\b-P\bP] [_\bd_\bi_\br]
              Change  the  current directory to _\bd_\bi_\br.  The variable H\bHO\bOM\bME\bE is the
              default _\bd_\bi_\br.  The variable C\bCD\bDP\bPA\bAT\bTH\bH defines the  search  path  for
              the  directory  containing  _\bd_\bi_\br.  Alternative directory names in
              C\bCD\bDP\bPA\bAT\bTH\bH are separated by a colon (:).  A null directory  name  in
              C\bCD\bDP\bPA\bAT\bTH\bH  is  the  same as the current directory, i.e., ``.\b.''.  If
              _\bd_\bi_\br begins with a slash (/), then C\bCD\bDP\bPA\bAT\bTH\bH is  not  used.  The  -\b-P\bP
              option  says  to use the physical directory structure instead of
              following symbolic links (see also the  -\b-P\bP  option  to  the  s\bse\bet\bt
              builtin command); the -\b-L\bL option forces symbolic links to be fol-
              lowed.  An argument of -\b- is equivalent to $\b$O\bOL\bLD\bDP\bPW\bWD\bD.   If  a  non-
              empty  directory  name from C\bCD\bDP\bPA\bAT\bTH\bH is used, or if -\b- is the first
              argument, and the directory change is successful,  the  absolute
              pathname of the new working directory is written to the standard
              output.  The return value is true if the directory was  success-
              fully changed; false otherwise.

       c\bca\bal\bll\ble\ber\br [_\be_\bx_\bp_\br]
              Returns the context of any active subroutine call (a shell func-
              tion or a script executed with the .\b. or s\bso\bou\bur\brc\bce\be builtins.   With-
              out _\be_\bx_\bp_\br, c\bca\bal\bll\ble\ber\br displays the line number and source filename of
              the current subroutine call.  If a non-negative integer is  sup-
              plied as _\be_\bx_\bp_\br, c\bca\bal\bll\ble\ber\br 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 _\be_\bx_\bp_\br does not correspond to a valid position  in
              the call stack.

       c\bco\bom\bmm\bma\ban\bnd\bd [-\b-p\bpV\bVv\bv] _\bc_\bo_\bm_\bm_\ba_\bn_\bd [_\ba_\br_\bg ...]
              Run  _\bc_\bo_\bm_\bm_\ba_\bn_\bd  with  _\ba_\br_\bg_\bs  suppressing  the normal shell function
              lookup. Only builtin commands or commands found in the P\bPA\bAT\bTH\bH  are
              executed.   If the -\b-p\bp option is given, the search for _\bc_\bo_\bm_\bm_\ba_\bn_\bd is
              performed using a default value for P\bPA\bAT\bTH\bH that is  guaranteed  to
              find  all  of  the  standard  utilities.  If either the -\b-V\bV or -\b-v\bv
              option is supplied, a description of _\bc_\bo_\bm_\bm_\ba_\bn_\bd is printed.  The -\b-v\bv
              option  causes a single word indicating the command or file name
              used to invoke _\bc_\bo_\bm_\bm_\ba_\bn_\bd to be displayed; the -\b-V\bV option produces a
              more  verbose  description.  If the -\b-V\bV or -\b-v\bv option is supplied,
              the exit status is 0 if _\bc_\bo_\bm_\bm_\ba_\bn_\bd was found, and  1  if  not.   If
              neither option is supplied and an error occurred or _\bc_\bo_\bm_\bm_\ba_\bn_\bd can-
              not be found, the exit status is 127.  Otherwise, the exit  sta-
              tus of the c\bco\bom\bmm\bma\ban\bnd\bd builtin is the exit status of _\bc_\bo_\bm_\bm_\ba_\bn_\bd.

       c\bco\bom\bmp\bpg\bge\ben\bn [_\bo_\bp_\bt_\bi_\bo_\bn] [_\bw_\bo_\br_\bd]
              Generate  possible  completion matches for _\bw_\bo_\br_\bd according to the
              _\bo_\bp_\bt_\bi_\bo_\bns, which may  be  any  option  accepted  by  the  c\bco\bom\bmp\bpl\ble\bet\bte\be
              builtin  with  the exception of -\b-p\bp and -\b-r\br, and write the matches
              to the standard output.  When using the -\b-F\bF or  -\b-C\bC  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 _\bw_\bo_\br_\bd is speci-
              fied, only those completions matching _\bw_\bo_\br_\bd will be displayed.

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

       c\bco\bom\bmp\bpl\ble\bet\bte\be [-\b-a\bab\bbc\bcd\bde\bef\bfg\bgj\bjk\bks\bsu\buv\bv] [-\b-o\bo _\bc_\bo_\bm_\bp_\b-_\bo_\bp_\bt_\bi_\bo_\bn] [-\b-A\bA _\ba_\bc_\bt_\bi_\bo_\bn] [-\b-G\bG _\bg_\bl_\bo_\bb_\bp_\ba_\bt]  [-\b-W\bW
       _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt] [-\b-P\bP _\bp_\br_\be_\bf_\bi_\bx] [-\b-S\bS _\bs_\bu_\bf_\bf_\bi_\bx]
              [-\b-X\bX _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt] [-\b-F\bF _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn] [-\b-C\bC _\bc_\bo_\bm_\bm_\ba_\bn_\bd] _\bn_\ba_\bm_\be [_\bn_\ba_\bm_\be _\b._\b._\b.]
       c\bco\bom\bmp\bpl\ble\bet\bte\be -\b-p\bpr\br [_\bn_\ba_\bm_\be ...]
              Specify how arguments to each _\bn_\ba_\bm_\be should be completed.  If  the
              -\b-p\bp  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 -\b-r\br option removes a completion spec-
              ification for each _\bn_\ba_\bm_\be, or, if no _\bn_\ba_\bm_\bes are supplied, all  com-
              pletion specifications.

              The  process  of  applying  these completion specifications when
              word completion is  attempted  is  described  above  under  P\bPr\bro\bo-\b-
              g\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn.

              Other  options,  if specified, have the following meanings.  The
              arguments to the -\b-G\bG, -\b-W\bW, and -\b-X\bX options (and, if necessary,  the
              -\b-P\bP  and -\b-S\bS options) should be quoted to protect them from expan-
              sion before the c\bco\bom\bmp\bpl\ble\bet\bte\be builtin is invoked.
              -\b-o\bo _\bc_\bo_\bm_\bp_\b-_\bo_\bp_\bt_\bi_\bo_\bn
                      The _\bc_\bo_\bm_\bp_\b-_\bo_\bp_\bt_\bi_\bo_\bn controls several aspects  of  the  comp-
                      spec's   behavior   beyond   the  simple  generation  of
                      completions.  _\bc_\bo_\bm_\bp_\b-_\bo_\bp_\bt_\bi_\bo_\bn may be one of:
                      b\bba\bas\bsh\bhd\bde\bef\bfa\bau\bul\blt\bt
                              Perform the rest of the default b\bba\bas\bsh\bh completions
                              if the compspec generates no matches.
                      d\bde\bef\bfa\bau\bul\blt\bt Use  readline's  default  filename completion if
                              the compspec generates no matches.
                      d\bdi\bir\brn\bna\bam\bme\bes\bs
                              Perform directory name completion if  the  comp-
                              spec generates no matches.
                      f\bfi\bil\ble\ben\bna\bam\bme\bes\bs
                              Tell  readline that the compspec generates file-
                              names, so it can perform  any  filename-specific
                              processing  (like  adding  a  slash to directory
                              names or suppressing trailing spaces).  Intended
                              to be used with shell functions.
                      n\bno\bos\bsp\bpa\bac\bce\be Tell   readline  not  to  append  a  space  (the
                              default) to words completed at the  end  of  the
                              line.
              -\b-A\bA _\ba_\bc_\bt_\bi_\bo_\bn
                      The  _\ba_\bc_\bt_\bi_\bo_\bn  may  be  one of the following to generate a
                      list of possible completions:
                      a\bal\bli\bia\bas\bs   Alias names.  May also be specified as -\b-a\ba.
                      a\bar\brr\bra\bay\byv\bva\bar\br
                              Array variable names.
                      b\bbi\bin\bnd\bdi\bin\bng\bg R\bRe\bea\bad\bdl\bli\bin\bne\be key binding names.
                      b\bbu\bui\bil\blt\bti\bin\bn Names of shell builtin commands.   May  also  be
                              specified as -\b-b\bb.
                      c\bco\bom\bmm\bma\ban\bnd\bd Command names.  May also be specified as -\b-c\bc.
                      d\bdi\bir\bre\bec\bct\bto\bor\bry\by
                              Directory names.  May also be specified as -\b-d\bd.
                      d\bdi\bis\bsa\bab\bbl\ble\bed\bd
                              Names of disabled shell builtins.
                      e\ben\bna\bab\bbl\ble\bed\bd Names of enabled shell builtins.
                      e\bex\bxp\bpo\bor\brt\bt  Names  of exported shell variables.  May also be
                              specified as -\b-e\be.
                      f\bfi\bil\ble\be    File names.  May also be specified as -\b-f\bf.
                      f\bfu\bun\bnc\bct\bti\bio\bon\bn
                              Names of shell functions.
                      g\bgr\bro\bou\bup\bp   Group names.  May also be specified as -\b-g\bg.
                      h\bhe\bel\blp\bpt\bto\bop\bpi\bic\bc
                              Help topics as accepted by the h\bhe\bel\blp\bp builtin.
                      h\bho\bos\bst\btn\bna\bam\bme\be
                              Hostnames, as taken from the file  specified  by
                              the H\bHO\bOS\bST\bTF\bFI\bIL\bLE\bE shell variable.
                      j\bjo\bob\bb     Job  names,  if job control is active.  May also
                              be specified as -\b-j\bj.
                      k\bke\bey\byw\bwo\bor\brd\bd Shell reserved words.  May also be specified  as
                              -\b-k\bk.
                      r\bru\bun\bnn\bni\bin\bng\bg Names of running jobs, if job control is active.
                      s\bse\ber\brv\bvi\bic\bce\be Service names.  May also be specified as -\b-s\bs.
                      s\bse\bet\bto\bop\bpt\bt  Valid arguments for the -\b-o\bo  option  to  the  s\bse\bet\bt
                              builtin.
                      s\bsh\bho\bop\bpt\bt   Shell  option  names  as  accepted  by the s\bsh\bho\bop\bpt\bt
                              builtin.
                      s\bsi\big\bgn\bna\bal\bl  Signal names.
                      s\bst\bto\bop\bpp\bpe\bed\bd Names of stopped jobs, if job control is active.
                      u\bus\bse\ber\br    User names.  May also be specified as -\b-u\bu.
                      v\bva\bar\bri\bia\bab\bbl\ble\be
                              Names of all shell variables.  May also be spec-
                              ified as -\b-v\bv.
              -\b-G\bG _\bg_\bl_\bo_\bb_\bp_\ba_\bt
                      The filename expansion pattern _\bg_\bl_\bo_\bb_\bp_\ba_\bt  is  expanded  to
                      generate the possible completions.
              -\b-W\bW _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt
                      The  _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt  is  split using the characters in the I\bIF\bFS\bS
                      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.
              -\b-C\bC _\bc_\bo_\bm_\bm_\ba_\bn_\bd
                      _\bc_\bo_\bm_\bm_\ba_\bn_\bd  is  executed in a subshell environment, and its
                      output is used as the possible completions.
              -\b-F\bF _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn
                      The shell function _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn is executed in  the  current
                      shell  environment.  When it finishes, the possible com-
                      pletions are retrieved from the value of  the  C\bCO\bOM\bMP\bPR\bRE\bEP\bPL\bLY\bY
                      array variable.
              -\b-X\bX _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt
                      _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt  is  a pattern as used for filename expansion.
                      It is applied to the list of possible completions gener-
                      ated  by  the  preceding options and arguments, and each
                      completion matching _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt is removed from the  list.
                      A  leading  !\b!  in _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt negates the pattern; in this
                      case, any completion not matching _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt is  removed.
              -\b-P\bP _\bp_\br_\be_\bf_\bi_\bx
                      _\bp_\br_\be_\bf_\bi_\bx  is  added at the beginning of each possible com-
                      pletion after all other options have been applied.
              -\b-S\bS _\bs_\bu_\bf_\bf_\bi_\bx
                      _\bs_\bu_\bf_\bf_\bi_\bx is appended to each possible completion after all
                      other options have been applied.

              The  return  value is true unless an invalid option is supplied,
              an option other than -\b-p\bp or -\b-r\br is supplied without a  _\bn_\ba_\bm_\be  argu-
              ment,  an  attempt  is made to remove a completion specification
              for a _\bn_\ba_\bm_\be for which no specification exists, or an error occurs
              adding a completion specification.

       c\bco\bon\bnt\bti\bin\bnu\bue\be [_\bn]
              Resume the next iteration of the enclosing f\bfo\bor\br, w\bwh\bhi\bil\ble\be, u\bun\bnt\bti\bil\bl, or
              s\bse\bel\ble\bec\bct\bt loop.  If _\bn is specified, resume  at  the  _\bnth  enclosing
              loop.   _\bn  must  be  >=  1.   If _\bn is greater than the number of
              enclosing loops, the  last  enclosing  loop  (the  ``top-level''
              loop) is resumed.  The return value is 0 unless the shell is not
              executing a loop when c\bco\bon\bnt\bti\bin\bnu\bue\be is executed.

       d\bde\bec\bcl\bla\bar\bre\be [-\b-a\baf\bfF\bFi\bir\brt\btx\bx] [-\b-p\bp] [_\bn_\ba_\bm_\be[=_\bv_\ba_\bl_\bu_\be] ...]
       t\bty\byp\bpe\bes\bse\bet\bt [-\b-a\baf\bfF\bFi\bir\brt\btx\bx] [-\b-p\bp] [_\bn_\ba_\bm_\be[=_\bv_\ba_\bl_\bu_\be] ...]
              Declare variables and/or give them attributes.  If no _\bn_\ba_\bm_\bes  are
              given  then display the values of variables.  The -\b-p\bp option will
              display the attributes and values of  each  _\bn_\ba_\bm_\be.   When  -\b-p\bp  is
              used,  additional  options  are ignored.  The -\b-F\bF option inhibits
              the display of function definitions; only the function name  and
              attributes are printed.  If the e\bex\bxt\btd\bde\beb\bbu\bug\bg shell option is enabled
              using s\bsh\bho\bop\bpt\bt, the source file name  and  line  number  where  the
              function  is  defined  are  displayed  as  well.   The -\b-F\bF option
              implies -\b-f\bf.  The following options can be used to restrict  out-
              put  to  variables with the specified attribute or to give vari-
              ables attributes:
              -\b-a\ba     Each _\bn_\ba_\bm_\be is an array variable (see A\bAr\brr\bra\bay\bys\bs above).
              -\b-f\bf     Use function names only.
              -\b-i\bi     The variable is treated as an integer; arithmetic evalua-
                     tion  (see  A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN )\b) is performed when the
                     variable is assigned a value.
              -\b-r\br     Make _\bn_\ba_\bm_\bes readonly.  These names cannot then be assigned
                     values by subsequent assignment statements or unset.
              -\b-t\bt     Give  each  _\bn_\ba_\bm_\be  the  _\bt_\br_\ba_\bc_\be attribute.  Traced functions
                     inherit the D\bDE\bEB\bBU\bUG\bG trap from the calling shell.  The trace
                     attribute has no special meaning for variables.
              -\b-x\bx     Mark  _\bn_\ba_\bm_\bes  for  export  to  subsequent commands via the
                     environment.

              Using `+' instead of `-' turns off the attribute  instead,  with
              the  exception that +\b+a\ba may not be used to destroy an array vari-
              able.  When used in a function, makes each _\bn_\ba_\bm_\be local,  as  with
              the  l\blo\boc\bca\bal\bl  command.   If a variable name is followed by =_\bv_\ba_\bl_\bu_\be,
              the value of the variable is set to _\bv_\ba_\bl_\bu_\be.  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 A\bAr\brr\bra\bay\bys\bs above), one of the _\bn_\ba_\bm_\be_\bs 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 -\b-f\bf.

       d\bdi\bir\brs\bs [\b[-\b-c\bcl\blp\bpv\bv]\b] [\b[+\b+_\bn]\b] [\b[-\b-_\bn]\b]
              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  p\bpu\bus\bsh\bhd\bd  command;  the  p\bpo\bop\bpd\bd  command  removes
              entries from the list.
              +\b+_\bn     Displays the _\bnth entry counting from the left of the list
                     shown by d\bdi\bir\brs\bs when invoked without options, starting with
                     zero.
              -\b-_\bn     Displays  the  _\bnth  entry  counting from the right of the
                     list shown by d\bdi\bir\brs\bs when invoked without options, starting
                     with zero.
              -\b-c\bc     Clears  the  directory  stack  by  deleting  all  of  the
                     entries.
              -\b-l\bl     Produces a longer listing;  the  default  listing  format
                     uses a tilde to denote the home directory.
              -\b-p\bp     Print the directory stack with one entry per line.
              -\b-v\bv     Print  the  directory stack with one entry per line, pre-
                     fixing each entry with its index in the stack.

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

       d\bdi\bis\bso\bow\bwn\bn [-\b-a\bar\br] [-\b-h\bh] [_\bj_\bo_\bb_\bs_\bp_\be_\bc ...]
              Without  options,  each  _\bj_\bo_\bb_\bs_\bp_\be_\bc  is  removed  from the table of
              active jobs.  If the -\b-h\bh option is given,  each  _\bj_\bo_\bb_\bs_\bp_\be_\bc  is  not
              removed from the table, but is marked so that S\bSI\bIG\bGH\bHU\bUP\bP is not sent
              to the job if the shell receives a S\bSI\bIG\bGH\bHU\bUP\bP.   If  no  _\bj_\bo_\bb_\bs_\bp_\be_\bc  is
              present,  and  neither the -\b-a\ba nor the -\b-r\br option is supplied, the
              _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb is used.  If no _\bj_\bo_\bb_\bs_\bp_\be_\bc is supplied, the  -\b-a\ba  option
              means  to  remove or mark all jobs; the -\b-r\br option without a _\bj_\bo_\bb_\b-
              _\bs_\bp_\be_\bc argument restricts operation to running jobs.   The  return
              value is 0 unless a _\bj_\bo_\bb_\bs_\bp_\be_\bc does not specify a valid job.

       e\bec\bch\bho\bo [-\b-n\bne\beE\bE] [_\ba_\br_\bg ...]
              Output  the  _\ba_\br_\bgs,  separated  by spaces, followed by a newline.
              The return status is always 0.  If -\b-n\bn is specified, the trailing
              newline  is  suppressed.  If the -\b-e\be option is given, interpreta-
              tion of the following backslash-escaped characters  is  enabled.
              The  -\b-E\bE option disables the interpretation of these escape char-
              acters, even on systems where they are interpreted  by  default.
              The  x\bxp\bpg\bg_\b_e\bec\bch\bho\bo  shell option may be used to dynamically determine
              whether or not e\bec\bch\bho\bo expands these escape characters by  default.
              e\bec\bch\bho\bo  does  not  interpret  -\b--\b- to mean the end of options.  e\bec\bch\bho\bo
              interprets the following escape sequences:
              \\b\a\ba     alert (bell)
              \\b\b\bb     backspace
              \\b\c\bc     suppress trailing newline
              \\b\e\be     an escape character
              \\b\f\bf     form feed
              \\b\n\bn     new line
              \\b\r\br     carriage return
              \\b\t\bt     horizontal tab
              \\b\v\bv     vertical tab
              \\b\\\b\     backslash
              \\b\0\b0_\bn_\bn_\bn  the eight-bit character whose value is  the  octal  value
                     _\bn_\bn_\bn (zero to three octal digits)
              \\b\_\bn_\bn_\bn   the  eight-bit  character  whose value is the octal value
                     _\bn_\bn_\bn (one to three octal digits)
              \\b\x\bx_\bH_\bH   the eight-bit character whose value  is  the  hexadecimal
                     value _\bH_\bH (one or two hex digits)

       e\ben\bna\bab\bbl\ble\be [-\b-a\bad\bdn\bnp\bps\bs] [-\b-f\bf _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be] [_\bn_\ba_\bm_\be ...]
              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  -\b-n\bn  is  used,  each  _\bn_\ba_\bm_\be  is disabled; otherwise, _\bn_\ba_\bm_\be_\bs are
              enabled.  For example, to use the t\bte\bes\bst\bt binary found via the P\bPA\bAT\bTH\bH
              instead  of  the  shell builtin version, run ``enable -n test''.
              The -\b-f\bf option means to load the new builtin  command  _\bn_\ba_\bm_\be  from
              shared object _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be, on systems that support dynamic loading.
              The -\b-d\bd option will delete a builtin previously loaded  with  -\b-f\bf.
              If no _\bn_\ba_\bm_\be arguments are given, or if the -\b-p\bp 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 -\b-n\bn
              is supplied, only disabled builtins are printed.  If -\b-a\ba is  sup-
              plied,  the  list printed includes all builtins, with an indica-
              tion of whether or not each is enabled.  If -\b-s\bs is supplied,  the
              output  is restricted to the POSIX _\bs_\bp_\be_\bc_\bi_\ba_\bl builtins.  The return
              value is 0 unless a _\bn_\ba_\bm_\be is not a shell builtin or there  is  an
              error loading a new builtin from a shared object.

       e\bev\bva\bal\bl [_\ba_\br_\bg ...]
              The  _\ba_\br_\bgs  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 e\bev\bva\bal\bl.  If there are
              no _\ba_\br_\bg_\bs, or only null arguments, e\bev\bva\bal\bl returns 0.

       e\bex\bxe\bec\bc [-\b-c\bcl\bl] [-\b-a\ba _\bn_\ba_\bm_\be] [_\bc_\bo_\bm_\bm_\ba_\bn_\bd [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]]
              If _\bc_\bo_\bm_\bm_\ba_\bn_\bd is specified, it replaces the shell.  No new  process
              is  created.  The _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs become the arguments to _\bc_\bo_\bm_\bm_\ba_\bn_\bd.  If
              the -\b-l\bl option is supplied, the shell places a dash at the begin-
              ning of the zeroth arg passed to _\bc_\bo_\bm_\bm_\ba_\bn_\bd.  This is what _\bl_\bo_\bg_\bi_\bn(1)
              does.  The -\b-c\bc option causes _\bc_\bo_\bm_\bm_\ba_\bn_\bd to be executed with an empty
              environment.   If  -\b-a\ba  is supplied, the shell passes _\bn_\ba_\bm_\be as the
              zeroth argument to the executed command.  If _\bc_\bo_\bm_\bm_\ba_\bn_\bd  cannot  be
              executed  for some reason, a non-interactive shell exits, unless
              the shell option e\bex\bxe\bec\bcf\bfa\bai\bil\bl is enabled, in which case  it  returns
              failure.   An interactive shell returns failure if the file can-
              not be executed.  If _\bc_\bo_\bm_\bm_\ba_\bn_\bd is not specified, any  redirections
              take  effect  in  the current shell, and the return status is 0.
              If there is a redirection error, the return status is 1.

       e\bex\bxi\bit\bt [_\bn]
              Cause the shell to exit with a status of _\bn.  If  _\bn  is  omitted,
              the exit status is that of the last command executed.  A trap on
              E\bEX\bXI\bIT\bT is executed before the shell terminates.

       e\bex\bxp\bpo\bor\brt\bt [-\b-f\bfn\bn] [_\bn_\ba_\bm_\be[=_\bw_\bo_\br_\bd]] ...
       e\bex\bxp\bpo\bor\brt\bt -\b-p\bp
              The supplied _\bn_\ba_\bm_\be_\bs are marked for automatic export to the  envi-
              ronment  of subsequently executed commands.  If the -\b-f\bf option is
              given, the _\bn_\ba_\bm_\be_\bs refer to functions.  If no _\bn_\ba_\bm_\be_\bs are given,  or
              if  the  -\b-p\bp  option  is  supplied,  a list of all names that are
              exported in this shell is printed.  The  -\b-n\bn  option  causes  the
              export  property  to  be  removed from each _\bn_\ba_\bm_\be.  If a variable
              name is followed by =_\bw_\bo_\br_\bd, the value of the variable is  set  to
              _\bw_\bo_\br_\bd.   e\bex\bxp\bpo\bor\brt\bt  returns  an  exit  status of 0 unless an invalid
              option is encountered, one of the _\bn_\ba_\bm_\be_\bs is  not  a  valid  shell
              variable name, or -\b-f\bf is supplied with a _\bn_\ba_\bm_\be that is not a func-
              tion.

       f\bfc\bc [-\b-e\be _\be_\bn_\ba_\bm_\be] [-\b-n\bnl\blr\br] [_\bf_\bi_\br_\bs_\bt] [_\bl_\ba_\bs_\bt]
       f\bfc\bc -\b-s\bs [_\bp_\ba_\bt=_\br_\be_\bp] [_\bc_\bm_\bd]
              Fix Command.  In the first form, a range of commands from  _\bf_\bi_\br_\bs_\bt
              to  _\bl_\ba_\bs_\bt  is selected from the history list.  _\bF_\bi_\br_\bs_\bt and _\bl_\ba_\bs_\bt may
              be specified as a string (to locate the last  command  beginning
              with  that  string)  or  as  a number (an index into the history
              list, where a negative number is used as an offset from the cur-
              rent command number).  If _\bl_\ba_\bs_\bt is not specified it is set to the
              current command for listing (so that ``fc -l  -10''  prints  the
              last 10 commands) and to _\bf_\bi_\br_\bs_\bt otherwise.  If _\bf_\bi_\br_\bs_\bt is not spec-
              ified it is set to the previous command for editing and -16  for
              listing.

              The  -\b-n\bn option suppresses the command numbers when listing.  The
              -\b-r\br option reverses the order of the commands.  If the -\b-l\bl  option
              is  given,  the  commands are listed on standard output.  Other-
              wise, the editor given by _\be_\bn_\ba_\bm_\be is invoked on a file  containing
              those  commands.  If _\be_\bn_\ba_\bm_\be is not given, the value of the F\bFC\bCE\bED\bDI\bIT\bT
              variable is used, and the value of E\bED\bDI\bIT\bTO\bOR\bR if F\bFC\bCE\bED\bDI\bIT\bT is not  set.
              If  neither  variable  is set, _\bv_\bi is used.  When editing is com-
              plete, the edited commands are echoed and executed.

              In the second form, _\bc_\bo_\bm_\bm_\ba_\bn_\bd is re-executed after  each  instance
              of  _\bp_\ba_\bt  is replaced by _\br_\be_\bp.  A useful alias to use with this is
              ``r="fc -s"'', so that typing ``r cc''  runs  the  last  command
              beginning with ``cc'' and typing ``r'' re-executes the last com-
              mand.

              If the first form is used, the  return  value  is  0  unless  an
              invalid  option  is encountered or _\bf_\bi_\br_\bs_\bt or _\bl_\ba_\bs_\bt specify history
              lines out of range.  If the -\b-e\be 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 _\bc_\bm_\bd does not specify  a  valid  history  line,  in
              which case f\bfc\bc returns failure.

       f\bfg\bg [_\bj_\bo_\bb_\bs_\bp_\be_\bc]
              Resume  _\bj_\bo_\bb_\bs_\bp_\be_\bc  in the foreground, and make it the current job.
              If _\bj_\bo_\bb_\bs_\bp_\be_\bc is not present, the shell's notion of the _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb
              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 _\bj_\bo_\bb_\bs_\bp_\be_\bc does not spec-
              ify a valid job or _\bj_\bo_\bb_\bs_\bp_\be_\bc specifies  a  job  that  was  started
              without job control.

       g\bge\bet\bto\bop\bpt\bts\bs _\bo_\bp_\bt_\bs_\bt_\br_\bi_\bn_\bg _\bn_\ba_\bm_\be [_\ba_\br_\bg_\bs]
              g\bge\bet\bto\bop\bpt\bts\bs  is used by shell procedures to parse positional parame-
              ters.  _\bo_\bp_\bt_\bs_\bt_\br_\bi_\bn_\bg 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,  g\bge\bet\bto\bop\bpt\bts\bs
              places  the next option in the shell variable _\bn_\ba_\bm_\be, initializing
              _\bn_\ba_\bm_\be if it does not exist, and the index of the next argument to
              be processed into the variable O\bOP\bPT\bTI\bIN\bND\bD.  O\bOP\bPT\bTI\bIN\bND\bD is initialized to
              1 each time the shell or a shell script  is  invoked.   When  an
              option  requires  an argument, g\bge\bet\bto\bop\bpt\bts\bs places that argument into
              the variable O\bOP\bPT\bTA\bAR\bRG\bG.  The shell does not reset O\bOP\bPT\bTI\bIN\bND\bD  automati-
              cally;  it  must  be  manually  reset  between multiple calls to
              g\bge\bet\bto\bop\bpt\bts\bs within the same shell invocation if a new set of parame-
              ters is to be used.

              When  the  end  of  options is encountered, g\bge\bet\bto\bop\bpt\bts\bs exits with a
              return value greater than zero.  O\bOP\bPT\bTI\bIN\bND\bD is set to the  index  of
              the first non-option argument, and n\bna\bam\bme\be is set to ?.

              g\bge\bet\bto\bop\bpt\bts\bs  normally  parses the positional parameters, but if more
              arguments are given in _\ba_\br_\bg_\bs, g\bge\bet\bto\bop\bpt\bts\bs parses those instead.

              g\bge\bet\bto\bop\bpt\bts\bs can report errors in two ways.  If the  first  character
              of  _\bo_\bp_\bt_\bs_\bt_\br_\bi_\bn_\bg  is  a  colon, _\bs_\bi_\bl_\be_\bn_\bt error reporting is used.  In
              normal operation diagnostic messages are  printed  when  invalid
              options  or  missing  option  arguments are encountered.  If the
              variable O\bOP\bPT\bTE\bER\bRR\bR is set to 0, no  error  messages  will  be  dis-
              played, even if the first character of _\bo_\bp_\bt_\bs_\bt_\br_\bi_\bn_\bg is not a colon.

              If an invalid option is seen, g\bge\bet\bto\bop\bpt\bts\bs places ? into _\bn_\ba_\bm_\be and, if
              not  silent,  prints  an  error  message  and unsets O\bOP\bPT\bTA\bAR\bRG\bG.  If
              g\bge\bet\bto\bop\bpt\bts\bs is silent, the  option  character  found  is  placed  in
              O\bOP\bPT\bTA\bAR\bRG\bG and no diagnostic message is printed.

              If  a required argument is not found, and g\bge\bet\bto\bop\bpt\bts\bs is not silent,
              a question mark (?\b?) is placed in _\bn_\ba_\bm_\be, O\bOP\bPT\bTA\bAR\bRG\bG is  unset,  and  a
              diagnostic  message  is  printed.   If g\bge\bet\bto\bop\bpt\bts\bs is silent, then a
              colon (:\b:) is placed in _\bn_\ba_\bm_\be and O\bOP\bPT\bTA\bAR\bRG\bG  is  set  to  the  option
              character found.

              g\bge\bet\bto\bop\bpt\bts\bs  returns true if an option, specified or unspecified, is
              found.  It returns false if the end of options is encountered or
              an error occurs.

       h\bha\bas\bsh\bh [-\b-l\blr\br] [-\b-p\bp _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be] [-\b-d\bdt\bt] [_\bn_\ba_\bm_\be]
              For  each  _\bn_\ba_\bm_\be, the full file name of the command is determined
              by searching the directories in $\b$P\bPA\bAT\bTH\bH and remembered.  If the -\b-p\bp
              option is supplied, no path search is performed, and _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be is
              used as the full file name of the command.  The -\b-r\br option causes
              the  shell  to  forget  all remembered locations.  The -\b-d\bd option
              causes the shell to forget the remembered location of each _\bn_\ba_\bm_\be.
              If  the  -\b-t\bt  option is supplied, the full pathname to which each
              _\bn_\ba_\bm_\be corresponds is printed.  If  multiple  _\bn_\ba_\bm_\be  arguments  are
              supplied  with  -\b-t\bt,  the  _\bn_\ba_\bm_\be is printed before the hashed full
              pathname.  The -\b-l\bl option causes output to be displayed in a for-
              mat  that may be reused as input.  If no arguments are given, or
              if only -\b-l\bl is supplied, information about remembered commands is
              printed.   The  return status is true unless a _\bn_\ba_\bm_\be is not found
              or an invalid option is supplied.

       h\bhe\bel\blp\bp [-\b-s\bs] [_\bp_\ba_\bt_\bt_\be_\br_\bn]
              Display helpful information about builtin commands.  If  _\bp_\ba_\bt_\bt_\be_\br_\bn
              is  specified, h\bhe\bel\blp\bp gives detailed help on all commands matching
              _\bp_\ba_\bt_\bt_\be_\br_\bn; otherwise help for all the builtins and  shell  control
              structures  is printed.  The -\b-s\bs option restricts the information
              displayed to a short usage synopsis.  The  return  status  is  0
              unless no command matches _\bp_\ba_\bt_\bt_\be_\br_\bn.

       h\bhi\bis\bst\bto\bor\bry\by [\b[_\bn]\b]
       h\bhi\bis\bst\bto\bor\bry\by -\b-c\bc
       h\bhi\bis\bst\bto\bor\bry\by -\b-d\bd _\bo_\bf_\bf_\bs_\be_\bt
       h\bhi\bis\bst\bto\bor\bry\by -\b-a\ban\bnr\brw\bw [_\bf_\bi_\bl_\be_\bn_\ba_\bm_\be]
       h\bhi\bis\bst\bto\bor\bry\by -\b-p\bp _\ba_\br_\bg [_\ba_\br_\bg _\b._\b._\b.]
       h\bhi\bis\bst\bto\bor\bry\by -\b-s\bs _\ba_\br_\bg [_\ba_\br_\bg _\b._\b._\b.]
              With no options, display the command history list with line num-
              bers.  Lines listed with a *\b* have been modified.  An argument of
              _\bn  lists only the last _\bn lines.  If the shell variable H\bHI\bIS\bST\bTT\bTI\bIM\bME\bE-\b-
              F\bFO\bOR\bRM\bMA\bAT\bT is set and not null, it is used as a  format  string  for
              _\bs_\bt_\br_\bf_\bt_\bi_\bm_\be(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 _\bf_\bi_\bl_\be_\bn_\ba_\bm_\be is
              supplied, it is used as the name of the history  file;  if  not,
              the  value  of H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE is used.  Options, if supplied, have the
              following meanings:
              -\b-c\bc     Clear the history list by deleting all the entries.
              -\b-d\bd _\bo_\bf_\bf_\bs_\be_\bt
                     Delete the history entry at position _\bo_\bf_\bf_\bs_\be_\bt.
              -\b-a\ba     Append the ``new'' history lines (history  lines  entered
                     since  the  beginning of the current b\bba\bas\bsh\bh session) to the
                     history file.
              -\b-n\bn     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 b\bba\bas\bsh\bh session.
              -\b-r\br     Read the contents of the history file and use them as the
                     current history.
              -\b-w\bw     Write the current history to the history file,  overwrit-
                     ing the history file's contents.
              -\b-p\bp     Perform  history  substitution  on the following _\ba_\br_\bg_\bs and
                     display the result on  the  standard  output.   Does  not
                     store  the results in the history list.  Each _\ba_\br_\bg must be
                     quoted to disable normal history expansion.
              -\b-s\bs     Store the _\ba_\br_\bg_\bs in the history list  as  a  single  entry.
                     The  last  command  in the history list is removed before
                     the _\ba_\br_\bg_\bs are added.

              If the H\bHI\bIS\bST\bTT\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT is set, the time stamp information associ-
              ated  with  each  history  entry is written to the history file.
              The return value is 0 unless an invalid option  is  encountered,
              an  error  occurs  while reading or writing the history file, an
              invalid _\bo_\bf_\bf_\bs_\be_\bt is supplied as an argument to -\b-d\bd, or the  history
              expansion supplied as an argument to -\b-p\bp fails.

       j\bjo\bob\bbs\bs [-\b-l\bln\bnp\bpr\brs\bs] [ _\bj_\bo_\bb_\bs_\bp_\be_\bc ... ]
       j\bjo\bob\bbs\bs -\b-x\bx _\bc_\bo_\bm_\bm_\ba_\bn_\bd [ _\ba_\br_\bg_\bs ... ]
              The first form lists the active jobs.  The options have the fol-
              lowing meanings:
              -\b-l\bl     List process IDs in addition to the normal information.
              -\b-p\bp     List only the process  ID  of  the  job's  process  group
                     leader.
              -\b-n\bn     Display  information  only  about  jobs that have changed
                     status since the user was last notified of their  status.
              -\b-r\br     Restrict output to running jobs.
              -\b-s\bs     Restrict output to stopped jobs.

              If  _\bj_\bo_\bb_\bs_\bp_\be_\bc  is given, output is restricted to information about
              that job.  The return status is 0 unless an  invalid  option  is
              encountered or an invalid _\bj_\bo_\bb_\bs_\bp_\be_\bc is supplied.

              If the -\b-x\bx option is supplied, j\bjo\bob\bbs\bs replaces any _\bj_\bo_\bb_\bs_\bp_\be_\bc found in
              _\bc_\bo_\bm_\bm_\ba_\bn_\bd or _\ba_\br_\bg_\bs with the corresponding  process  group  ID,  and
              executes _\bc_\bo_\bm_\bm_\ba_\bn_\bd passing it _\ba_\br_\bg_\bs, returning its exit status.

       k\bki\bil\bll\bl [-\b-s\bs _\bs_\bi_\bg_\bs_\bp_\be_\bc | -\b-n\bn _\bs_\bi_\bg_\bn_\bu_\bm | -\b-_\bs_\bi_\bg_\bs_\bp_\be_\bc] [_\bp_\bi_\bd | _\bj_\bo_\bb_\bs_\bp_\be_\bc] ...
       k\bki\bil\bll\bl -\b-l\bl [_\bs_\bi_\bg_\bs_\bp_\be_\bc | _\be_\bx_\bi_\bt_\b__\bs_\bt_\ba_\bt_\bu_\bs]
              Send  the  signal  named  by  _\bs_\bi_\bg_\bs_\bp_\be_\bc or _\bs_\bi_\bg_\bn_\bu_\bm to the processes
              named by _\bp_\bi_\bd or _\bj_\bo_\bb_\bs_\bp_\be_\bc.  _\bs_\bi_\bg_\bs_\bp_\be_\bc is either  a  case-insensitive
              signal  name such as S\bSI\bIG\bGK\bKI\bIL\bLL\bL (with or without the S\bSI\bIG\bG prefix) or
              a signal number; _\bs_\bi_\bg_\bn_\bu_\bm is a signal number.  If _\bs_\bi_\bg_\bs_\bp_\be_\bc  is  not
              present,  then  S\bSI\bIG\bGT\bTE\bER\bRM\bM is assumed.  An argument of -\b-l\bl lists the
              signal names.  If any arguments are supplied when -\b-l\bl  is  given,
              the  names  of  the  signals  corresponding to the arguments are
              listed, and the return status is 0.  The _\be_\bx_\bi_\bt_\b__\bs_\bt_\ba_\bt_\bu_\bs argument to
              -\b-l\bl  is  a  number  specifying either a signal number or the exit
              status of a process terminated by a signal.  k\bki\bil\bll\bl  returns  true
              if  at  least  one  signal was successfully sent, or false if an
              error occurs or an invalid option is encountered.

       l\ble\bet\bt _\ba_\br_\bg [_\ba_\br_\bg ...]
              Each _\ba_\br_\bg is an arithmetic expression to be evaluated (see A\bAR\bRI\bIT\bTH\bH-\b-
              M\bME\bET\bTI\bIC\bC  E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN).  If the last _\ba_\br_\bg evaluates to 0, l\ble\bet\bt returns
              1; 0 is returned otherwise.

       l\blo\boc\bca\bal\bl [_\bo_\bp_\bt_\bi_\bo_\bn] [_\bn_\ba_\bm_\be[=_\bv_\ba_\bl_\bu_\be] ...]
              For each argument, a local variable named _\bn_\ba_\bm_\be is  created,  and
              assigned  _\bv_\ba_\bl_\bu_\be.   The _\bo_\bp_\bt_\bi_\bo_\bn can be any of the options accepted
              by d\bde\bec\bcl\bla\bar\bre\be.  When l\blo\boc\bca\bal\bl is used within a function, it causes the
              variable  _\bn_\ba_\bm_\be  to have a visible scope restricted to that func-
              tion and its children.  With no operands, l\blo\boc\bca\bal\bl writes a list of
              local  variables  to the standard output.  It is an error to use
              l\blo\boc\bca\bal\bl when not within a function.  The return status is 0 unless
              l\blo\boc\bca\bal\bl  is  used outside a function, an invalid _\bn_\ba_\bm_\be is supplied,
              or _\bn_\ba_\bm_\be is a readonly variable.

       l\blo\bog\bgo\bou\but\bt Exit a login shell.

       p\bpo\bop\bpd\bd [-n\bn] [+_\bn] [-_\bn]
              Removes entries from the directory stack.   With  no  arguments,
              removes  the  top directory from the stack, and performs a c\bcd\bd to
              the new top directory.  Arguments, if supplied, have the follow-
              ing meanings:
              +\b+_\bn     Removes  the _\bnth entry counting from the left of the list
                     shown by d\bdi\bir\brs\bs, starting with zero.  For  example:  ``popd
                     +0'' removes the first directory, ``popd +1'' the second.
              -\b-_\bn     Removes the _\bnth entry counting from the right of the list
                     shown  by  d\bdi\bir\brs\bs, starting with zero.  For example: ``popd
                     -0'' removes the last directory, ``popd -1'' the next  to
                     last.
              -\b-n\bn     Suppresses  the  normal change of directory when removing
                     directories from the stack, so that  only  the  stack  is
                     manipulated.

              If  the p\bpo\bop\bpd\bd command is successful, a d\bdi\bir\brs\bs is performed as well,
              and the return status is 0.  p\bpo\bop\bpd\bd 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.

       p\bpr\bri\bin\bnt\btf\bf _\bf_\bo_\br_\bm_\ba_\bt [_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs]
              Write  the  formatted _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs to the standard output under the
              control of the _\bf_\bo_\br_\bm_\ba_\bt.  The _\bf_\bo_\br_\bm_\ba_\bt is a character  string  which
              contains  three  types  of  objects: plain characters, which are
              simply copied to standard output,  character  escape  sequences,
              which  are converted and copied to the standard output, and for-
              mat specifications, each of which causes printing  of  the  next
              successive _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt.  In addition to the standard _\bp_\br_\bi_\bn_\bt_\bf(1) for-
              mats, %\b%b\bb causes p\bpr\bri\bin\bnt\btf\bf to expand backslash escape  sequences  in
              the  corresponding  _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt  (except that \\b\c\bc terminates output,
              backslashes in \\b\'\b', \\b\"\b", and \\b\?\b? are not removed, and octal escapes
              beginning  with \\b\0\b0 may contain up to four digits), and %\b%q\bq causes
              p\bpr\bri\bin\bnt\btf\bf to output the corresponding _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt in a format that can
              be reused as shell input.

              The  _\bf_\bo_\br_\bm_\ba_\bt  is  reused as necessary to consume all of the _\ba_\br_\bg_\bu_\b-
              _\bm_\be_\bn_\bt_\bs.  If the _\bf_\bo_\br_\bm_\ba_\bt requires more _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs 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.

       p\bpu\bus\bsh\bhd\bd [-\b-n\bn] [_\bd_\bi_\br]
       p\bpu\bus\bsh\bhd\bd [-\b-n\bn] [+_\bn] [-_\bn]
              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:
              +\b+_\bn     Rotates  the  stack  so  that the _\bnth directory (counting
                     from the left of the list shown by  d\bdi\bir\brs\bs,  starting  with
                     zero) is at the top.
              -\b-_\bn     Rotates  the  stack  so  that the _\bnth directory (counting
                     from the right of the list shown by d\bdi\bir\brs\bs,  starting  with
                     zero) is at the top.
              -\b-n\bn     Suppresses  the  normal  change  of directory when adding
                     directories to the stack,  so  that  only  the  stack  is
                     manipulated.
              _\bd_\bi_\br    Adds _\bd_\bi_\br to the directory stack at the top, making it the
                     new current working directory.

              If the p\bpu\bus\bsh\bhd\bd command is successful, a d\bdi\bir\brs\bs is performed as well.
              If  the first form is used, p\bpu\bus\bsh\bhd\bd returns 0 unless the cd to _\bd_\bi_\br
              fails.  With the second form, p\bpu\bus\bsh\bhd\bd 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.

       p\bpw\bwd\bd [-\b-L\bLP\bP]
              Print  the  absolute  pathname of the current working directory.
              The pathname printed contains no symbolic links if the -\b-P\bP option
              is supplied or the -\b-o\bo p\bph\bhy\bys\bsi\bic\bca\bal\bl option to the s\bse\bet\bt builtin command
              is enabled.  If the -\b-L\bL 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.

       r\bre\bea\bad\bd [-\b-e\ber\brs\bs] [-\b-u\bu _\bf_\bd] [-\b-t\bt _\bt_\bi_\bm_\be_\bo_\bu_\bt] [-\b-a\ba _\ba_\bn_\ba_\bm_\be] [-\b-p\bp _\bp_\br_\bo_\bm_\bp_\bt] [-\b-n\bn _\bn_\bc_\bh_\ba_\br_\bs] [-\b-d\bd
       _\bd_\be_\bl_\bi_\bm] [_\bn_\ba_\bm_\be ...]
              One  line  is  read  from  the  standard input, or from the file
              descriptor _\bf_\bd supplied as an argument to the -\b-u\bu option, and  the
              first word is assigned to the first _\bn_\ba_\bm_\be, the second word to the
              second _\bn_\ba_\bm_\be, and so on, with leftover words and their  interven-
              ing  separators  assigned  to the last _\bn_\ba_\bm_\be.  If there are fewer
              words read from the input stream than names, the remaining names
              are  assigned  empty  values.  The characters in I\bIF\bFS\bS are used to
              split the line into words.  The backslash character (\\b\)  may  be
              used  to  remove any special meaning for the next character read
              and for line continuation.  Options, if supplied, have the  fol-
              lowing meanings:
              -\b-a\ba _\ba_\bn_\ba_\bm_\be
                     The words are assigned to sequential indices of the array
                     variable _\ba_\bn_\ba_\bm_\be, starting at 0.  _\ba_\bn_\ba_\bm_\be is unset before any
                     new  values  are  assigned.   Other  _\bn_\ba_\bm_\be  arguments  are
                     ignored.
              -\b-d\bd _\bd_\be_\bl_\bi_\bm
                     The first character of _\bd_\be_\bl_\bi_\bm is  used  to  terminate  the
                     input line, rather than newline.
              -\b-e\be     If the standard input is coming from a terminal, r\bre\bea\bad\bdl\bli\bin\bne\be
                     (see R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE above) is used to obtain the line.
              -\b-n\bn _\bn_\bc_\bh_\ba_\br_\bs
                     r\bre\bea\bad\bd returns after reading _\bn_\bc_\bh_\ba_\br_\bs characters rather  than
                     waiting for a complete line of input.
              -\b-p\bp _\bp_\br_\bo_\bm_\bp_\bt
                     Display _\bp_\br_\bo_\bm_\bp_\bt 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.
              -\b-r\br     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.
              -\b-s\bs     Silent mode.  If input is coming from a terminal, charac-
                     ters are not echoed.
              -\b-t\bt _\bt_\bi_\bm_\be_\bo_\bu_\bt
                     Cause  r\bre\bea\bad\bd  to time out and return failure if a complete
                     line of input is not read within _\bt_\bi_\bm_\be_\bo_\bu_\bt  seconds.   This
                     option  has  no  effect if r\bre\bea\bad\bd is not reading input from
                     the terminal or a pipe.
              -\b-u\bu _\bf_\bd  Read input from file descriptor _\bf_\bd.

              If no _\bn_\ba_\bm_\be_\bs are supplied, the line read is assigned to the vari-
              able  R\bRE\bEP\bPL\bLY\bY.   The  return  code  is zero, unless end-of-file is
              encountered, r\bre\bea\bad\bd times out, or an invalid  file  descriptor  is
              supplied as the argument to -\b-u\bu.

       r\bre\bea\bad\bdo\bon\bnl\bly\by [-\b-a\bap\bpf\bf] [_\bn_\ba_\bm_\be[=_\bw_\bo_\br_\bd] ...]
              The  given  _\bn_\ba_\bm_\be_\bs are marked readonly; the values of these _\bn_\ba_\bm_\be_\bs
              may not be changed by subsequent assignment.  If the  -\b-f\bf  option
              is  supplied,  the  functions  corresponding to the _\bn_\ba_\bm_\be_\bs are so
              marked.  The -\b-a\ba option restricts the variables to arrays.  If no
              _\bn_\ba_\bm_\be  arguments  are  given,  or if the -\b-p\bp option is supplied, a
              list of all readonly names is printed.   The  -\b-p\bp  option  causes
              output  to be displayed in a format that may be reused as input.
              If a variable name is followed by =_\bw_\bo_\br_\bd, the value of the  vari-
              able  is  set to _\bw_\bo_\br_\bd.  The return status is 0 unless an invalid
              option is encountered, one of the _\bn_\ba_\bm_\be_\bs is  not  a  valid  shell
              variable name, or -\b-f\bf is supplied with a _\bn_\ba_\bm_\be that is not a func-
              tion.

       r\bre\bet\btu\bur\brn\bn [_\bn]
              Causes a function to exit with the return value specified by  _\bn.
              If  _\bn  is omitted, the return status is that of the last command
              executed in the function body.  If used outside a function,  but
              during  execution  of  a  script  by the .\b.  (s\bso\bou\bur\brc\bce\be) command, it
              causes the shell to stop executing that script and return either
              _\bn  or  the  exit  status of the last command executed within the
              script as the exit status of the  script.   If  used  outside  a
              function  and  not during execution of a script by .\b., the return
              status is false.  Any command associated with the R\bRE\bET\bTU\bUR\bRN\bN trap is
              executed  before execution resumes after the function or script.

       s\bse\bet\bt [-\b--\b-a\bab\bbe\bef\bfh\bhk\bkm\bmn\bnp\bpt\btu\buv\bvx\bxB\bBC\bCH\bHP\bP] [-\b-o\bo _\bo_\bp_\bt_\bi_\bo_\bn] [_\ba_\br_\bg ...]
              Without options, the name and value of each shell  variable  are
              displayed  in  a format that can be reused as input.  The output
              is sorted according to the current  locale.   When  options  are
              specified,  they  set  or unset shell attributes.  Any arguments
              remaining after the options are processed are treated as  values
              for the positional parameters and are assigned, in order, to $\b$1\b1,
              $\b$2\b2, .\b..\b..\b.  $\b$_\bn.  Options, if specified, have  the  following  mean-
              ings:
              -\b-a\ba      Automatically  mark  variables  and  functions which are
                      modified or created for export  to  the  environment  of
                      subsequent commands.
              -\b-b\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.
              -\b-e\be      Exit  immediately if a _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd (see S\bSH\bHE\bEL\bLL\bL G\bGR\bRA\bAM\bMM\bMA\bAR\bR
                      above) exits with a non-zero status.  The shell does not
                      exit  if  the  command that fails is part of the command
                      list immediately following a  w\bwh\bhi\bil\ble\be  or  u\bun\bnt\bti\bil\bl  keyword,
                      part  of the test in an _\bi_\bf statement, part of a &\b&&\b& or |\b||\b|
                      list, or if the command's return value is being inverted
                      via  !\b!.   A  trap on E\bER\bRR\bR, if set, is executed before the
                      shell exits.
              -\b-f\bf      Disable pathname expansion.
              -\b-h\bh      Remember the location of commands as they are looked  up
                      for execution.  This is enabled by default.
              -\b-k\bk      All  arguments  in the form of assignment statements are
                      placed in the environment for a command, not just  those
                      that precede the command name.
              -\b-m\bm      Monitor  mode.   Job control is enabled.  This option is
                      on by default for interactive  shells  on  systems  that
                      support  it  (see  J\bJO\bOB\bB  C\bCO\bON\bNT\bTR\bRO\bOL\bL above).  Background pro-
                      cesses run in a separate process group and a  line  con-
                      taining  their exit status is printed upon their comple-
                      tion.
              -\b-n\bn      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.
              -\b-o\bo _\bo_\bp_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be
                      The _\bo_\bp_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be can be one of the following:
                      a\bal\bll\ble\bex\bxp\bpo\bor\brt\bt
                              Same as -\b-a\ba.
                      b\bbr\bra\bac\bce\bee\bex\bxp\bpa\ban\bnd\bd
                              Same as -\b-B\bB.
                      e\bem\bma\bac\bcs\bs   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 -\b--\b-n\bno\boe\bed\bdi\bit\bti\bin\bng\bg option.
                      e\ber\brr\brt\btr\bra\bac\bce\be
                              Same as -\b-E\bE.
                      f\bfu\bun\bnc\bct\btr\bra\bac\bce\be
                              Same as -\b-T\bT.
                      e\ber\brr\bre\bex\bxi\bit\bt Same as -\b-e\be.
                      h\bha\bas\bsh\bha\bal\bll\bl Same as -\b-h\bh.
                      h\bhi\bis\bst\bte\bex\bxp\bpa\ban\bnd\bd
                              Same as -\b-H\bH.
                      h\bhi\bis\bst\bto\bor\bry\by Enable command history, as described above under
                              H\bHI\bIS\bST\bTO\bOR\bRY\bY.  This option is on by default in inter-
                              active shells.
                      i\big\bgn\bno\bor\bre\bee\beo\bof\bf
                              The   effect   is   as   if  the  shell  command
                              ``IGNOREEOF=10'' had been  executed  (see  S\bSh\bhe\bel\bll\bl
                              V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs above).
                      k\bke\bey\byw\bwo\bor\brd\bd Same as -\b-k\bk.
                      m\bmo\bon\bni\bit\bto\bor\br Same as -\b-m\bm.
                      n\bno\boc\bcl\blo\bob\bbb\bbe\ber\br
                              Same as -\b-C\bC.
                      n\bno\boe\bex\bxe\bec\bc  Same as -\b-n\bn.
                      n\bno\bog\bgl\blo\bob\bb  Same as -\b-f\bf.  n\bno\bol\blo\bog\bg Currently ignored.
                      n\bno\bot\bti\bif\bfy\by  Same as -\b-b\bb.
                      n\bno\bou\bun\bns\bse\bet\bt Same as -\b-u\bu.
                      o\bon\bne\bec\bcm\bmd\bd  Same as -\b-t\bt.
                      p\bph\bhy\bys\bsi\bic\bca\bal\bl
                              Same as -\b-P\bP.
                      p\bpi\bip\bpe\bef\bfa\bai\bil\bl
                              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.
                      p\bpo\bos\bsi\bix\bx   Change  the  behavior  of b\bba\bas\bsh\bh where the default
                              operation differs from the POSIX 1003.2 standard
                              to match the standard (_\b`_\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be).
                      p\bpr\bri\biv\bvi\bil\ble\beg\bge\bed\bd
                              Same as -\b-p\bp.
                      v\bve\ber\brb\bbo\bos\bse\be Same as -\b-v\bv.
                      v\bvi\bi      Use a vi-style command line editing interface.
                      x\bxt\btr\bra\bac\bce\be  Same as -\b-x\bx.
                      If -\b-o\bo is supplied with no _\bo_\bp_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be, the values of the
                      current options are printed.  If +\b+o\bo is supplied with  no
                      _\bo_\bp_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be,  a  series  of s\bse\bet\bt commands to recreate the
                      current option settings is  displayed  on  the  standard
                      output.
              -\b-p\bp      Turn  on  _\bp_\br_\bi_\bv_\bi_\bl_\be_\bg_\be_\bd  mode.   In this mode, the $\b$E\bEN\bNV\bV and
                      $\b$B\bBA\bAS\bSH\bH_\b_E\bEN\bNV\bV files are not processed, shell  functions  are
                      not  inherited  from  the environment, and the S\bSH\bHE\bEL\bLL\bLO\bOP\bPT\bTS\bS
                      variable, if it appears in the environment, is  ignored.
                      If  the shell is started with the effective user (group)
                      id not equal to the real user (group)  id,  and  the  -\b-p\bp
                      option  is not supplied, these actions are taken and the
                      effective user id is set to the real user id.  If the -\b-p\bp
                      option  is supplied 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.
              -\b-t\bt      Exit after reading and executing one command.
              -\b-u\bu      Treat unset variables as an error when performing param-
                      eter  expansion.   If expansion is attempted on an unset
                      variable, the shell prints an error message, and, if not
                      interactive, exits with a non-zero status.
              -\b-v\bv      Print shell input lines as they are read.
              -\b-x\bx      After  expanding  each _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd, f\bfo\bor\br command, c\bca\bas\bse\be
                      command, s\bse\bel\ble\bec\bct\bt command, or arithmetic f\bfo\bor\br command, dis-
                      play  the expanded value of P\bPS\bS4\b4, followed by the command
                      and its expanded arguments or associated word list.
              -\b-B\bB      The shell performs brace expansion (see B\bBr\bra\bac\bce\be  E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
                      above).  This is on by default.
              -\b-C\bC      If  set,  b\bba\bas\bsh\bh  does not overwrite an existing file with
                      the >\b>, >\b>&\b&, and <\b<>\b> redirection operators.   This  may  be
                      overridden when creating output files by using the redi-
                      rection operator >\b>|\b| instead of >\b>.
              -\b-E\bE      If set, any trap on E\bER\bRR\bR is inherited by shell functions,
                      command  substitutions,  and commands executed in a sub-
                      shell environment.  The E\bER\bRR\bR trap is normally not  inher-
                      ited in such cases.
              -\b-H\bH      Enable !\b!  style history substitution.  This option is on
                      by default when the shell is interactive.
              -\b-P\bP      If set, the shell does not follow  symbolic  links  when
                      executing  commands  such  as c\bcd\bd that change the current
                      working  directory.   It  uses  the  physical  directory
                      structure instead.  By default, b\bba\bas\bsh\bh follows the logical
                      chain of  directories  when  performing  commands  which
                      change the current directory.
              -\b-T\bT      If  set,  any  trap on D\bDE\bEB\bBU\bUG\bG is inherited by shell func-
                      tions, command substitutions, and commands executed in a
                      subshell  environment.   The  D\bDE\bEB\bBU\bUG\bG trap is normally not
                      inherited in such cases.
              -\b--\b-      If no arguments follow this option, then the  positional
                      parameters are unset.  Otherwise, the positional parame-
                      ters are set to the _\ba_\br_\bgs, even if  some  of  them  begin
                      with a -\b-.
              -\b-       Signal  the  end of options, cause all remaining _\ba_\br_\bgs to
                      be assigned to the positional parameters.  The -\b-x\bx and -\b-v\bv
                      options are turned off.  If there are no _\ba_\br_\bgs, 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 $\b$-\b-.  The
              return status is always true unless an invalid option is encoun-
              tered.

       s\bsh\bhi\bif\bft\bt [_\bn]
              The  positional  parameters  from _\bn+1 ... are renamed to $\b$1\b1 .\b..\b..\b..\b.
              Parameters represented by the numbers  $\b$#\b#  down  to  $\b$#\b#-_\bn+1  are
              unset.   _\bn  must  be a non-negative number less than or equal to
              $\b$#\b#.  If _\bn is 0, no parameters are changed.  If _\bn is  not  given,
              it  is assumed to be 1.  If _\bn is greater than $\b$#\b#, the positional
              parameters are not changed.  The return status is  greater  than
              zero if _\bn is greater than $\b$#\b# or less than zero; otherwise 0.

       s\bsh\bho\bop\bpt\bt [-\b-p\bpq\bqs\bsu\bu] [-\b-o\bo] [_\bo_\bp_\bt_\bn_\ba_\bm_\be ...]
              Toggle the values of variables controlling optional shell behav-
              ior.  With no options, or with the -\b-p\bp option, a list of all set-
              table options is displayed, with an indication of whether or not
              each is set.  The -\b-p\bp option causes output to be displayed  in  a
              form  that  may be reused as input.  Other options have the fol-
              lowing meanings:
              -\b-s\bs     Enable (set) each _\bo_\bp_\bt_\bn_\ba_\bm_\be.
              -\b-u\bu     Disable (unset) each _\bo_\bp_\bt_\bn_\ba_\bm_\be.
              -\b-q\bq     Suppresses normal output (quiet mode); the return  status
                     indicates whether the _\bo_\bp_\bt_\bn_\ba_\bm_\be is set or unset.  If multi-
                     ple _\bo_\bp_\bt_\bn_\ba_\bm_\be arguments are given with -\b-q\bq, the return  sta-
                     tus  is zero if all _\bo_\bp_\bt_\bn_\ba_\bm_\be_\bs are enabled; non-zero other-
                     wise.
              -\b-o\bo     Restricts the values of _\bo_\bp_\bt_\bn_\ba_\bm_\be to be those  defined  for
                     the -\b-o\bo option to the s\bse\bet\bt builtin.

              If  either  -\b-s\bs or -\b-u\bu is used with no _\bo_\bp_\bt_\bn_\ba_\bm_\be arguments, the dis-
              play is limited to those options which are set or unset, respec-
              tively.   Unless otherwise noted, the s\bsh\bho\bop\bpt\bt options are disabled
              (unset) by default.

              The return status when listing options is zero if  all  _\bo_\bp_\bt_\bn_\ba_\bm_\be_\bs
              are  enabled,  non-zero  otherwise.   When  setting or unsetting
              options, the return status is zero unless an _\bo_\bp_\bt_\bn_\ba_\bm_\be  is  not  a
              valid shell option.

              The list of s\bsh\bho\bop\bpt\bt options is:

              c\bcd\bda\bab\bbl\ble\be_\b_v\bva\bar\brs\bs
                      If  set,  an  argument to the c\bcd\bd builtin command that is
                      not a directory is assumed to be the name of a  variable
                      whose value is the directory to change to.
              c\bcd\bds\bsp\bpe\bel\bll\bl If set, minor errors in the spelling of a directory com-
                      ponent in a c\bcd\bd command will be  corrected.   The  errors
                      checked for are transposed characters, a missing charac-
                      ter, and one character too many.   If  a  correction  is
                      found,  the corrected file name is printed, and the com-
                      mand proceeds.  This option is only used by  interactive
                      shells.
              c\bch\bhe\bec\bck\bkh\bha\bas\bsh\bh
                      If set, b\bba\bas\bsh\bh 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.
              c\bch\bhe\bec\bck\bkw\bwi\bin\bns\bsi\biz\bze\be
                      If set, b\bba\bas\bsh\bh checks the window size after  each  command
                      and,  if  necessary,  updates  the  values  of L\bLI\bIN\bNE\bES\bS and
                      C\bCO\bOL\bLU\bUM\bMN\bNS\bS.
              c\bcm\bmd\bdh\bhi\bis\bst\bt If set, b\bba\bas\bsh\bh attempts to save all lines of  a  multiple-
                      line  command  in  the  same history entry.  This allows
                      easy re-editing of multi-line commands.
              d\bdo\bot\btg\bgl\blo\bob\bb If set, b\bba\bas\bsh\bh includes filenames beginning with a `.'  in
                      the results of pathname expansion.
              e\bex\bxe\bec\bcf\bfa\bai\bil\bl
                      If set, a non-interactive shell will not exit if it can-
                      not execute the file specified as  an  argument  to  the
                      e\bex\bxe\bec\bc  builtin  command.   An  interactive shell does not
                      exit if e\bex\bxe\bec\bc fails.
              e\bex\bxp\bpa\ban\bnd\bd_\b_a\bal\bli\bia\bas\bse\bes\bs
                      If set, aliases are expanded as  described  above  under
                      A\bAL\bLI\bIA\bAS\bSE\bES\bS.  This option is enabled by default for interac-
                      tive shells.
              e\bex\bxt\btd\bde\beb\bbu\bug\bg
                      If set,  behavior  intended  for  use  by  debuggers  is
                      enabled:
                      1\b1.\b.     The -\b-F\bF option to the d\bde\bec\bcl\bla\bar\bre\be builtin displays the
                             source file name and line number corresponding to
                             each function name supplied as an argument.
                      2\b2.\b.     If  the  command  run by the D\bDE\bEB\bBU\bUG\bG trap returns a
                             non-zero value, the next command is  skipped  and
                             not executed.
                      3\b3.\b.     If  the  command  run by the D\bDE\bEB\bBU\bUG\bG 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 .\b. or s\bso\bou\bur\brc\bce\be  builtins),  a  call  to
                             r\bre\bet\btu\bur\brn\bn is simulated.
              e\bex\bxt\btg\bgl\blo\bob\bb If set, the extended pattern matching features described
                      above under P\bPa\bat\bth\bhn\bna\bam\bme\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn are enabled.
              e\bex\bxt\btq\bqu\buo\bot\bte\be
                      If set, $\b$'_\bs_\bt_\br_\bi_\bn_\bg' and  $\b$"_\bs_\bt_\br_\bi_\bn_\bg"  quoting  is  performed
                      within   $\b${\b{_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br}\b}   expansions  enclosed  in  double
                      quotes.  This option is enabled by default.
              f\bfa\bai\bil\blg\bgl\blo\bob\bb
                      If set, patterns which fail to  match  filenames  during
                      pathname expansion result in an expansion error.
              f\bfo\bor\brc\bce\be_\b_f\bfi\big\bgn\bno\bor\bre\be
                      If  set,  the  suffixes  specified  by the F\bFI\bIG\bGN\bNO\bOR\bRE\bE shell
                      variable cause words to be ignored when performing  word
                      completion even if the ignored words are the only possi-
                      ble  completions.   See  S\bSH\bHE\bEL\bLL\bL  V\bVA\bAR\bRI\bIA\bAB\bBL\bLE\bES\bS  above  for  a
                      description  of  F\bFI\bIG\bGN\bNO\bOR\bRE\bE.   This  option  is  enabled by
                      default.
              g\bgn\bnu\bu_\b_e\ber\brr\brf\bfm\bmt\bt
                      If set, shell error messages are written in the standard
                      GNU error message format.
              h\bhi\bis\bst\bta\bap\bpp\bpe\ben\bnd\bd
                      If  set,  the history list is appended to the file named
                      by the value of the H\bHI\bIS\bST\bTF\bFI\bIL\bLE\bE  variable  when  the  shell
                      exits, rather than overwriting the file.
              h\bhi\bis\bst\btr\bre\bee\bed\bdi\bit\bt
                      If  set, and r\bre\bea\bad\bdl\bli\bin\bne\be is being used, a user is given the
                      opportunity to re-edit a failed history substitution.
              h\bhi\bis\bst\btv\bve\ber\bri\bif\bfy\by
                      If set, and r\bre\bea\bad\bdl\bli\bin\bne\be 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 r\bre\bea\bad\bdl\bli\bin\bne\be editing buffer, allowing further modi-
                      fication.
              h\bho\bos\bst\btc\bco\bom\bmp\bpl\ble\bet\bte\be
                      If set, and r\bre\bea\bad\bdl\bli\bin\bne\be is being used, b\bba\bas\bsh\bh will attempt to
                      perform  hostname  completion when a word containing a @\b@
                      is  being  completed  (see  C\bCo\bom\bmp\bpl\ble\bet\bti\bin\bng\bg  under   R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE
                      above).  This is enabled by default.
              h\bhu\bup\bpo\bon\bne\bex\bxi\bit\bt
                      If set, b\bba\bas\bsh\bh will send S\bSI\bIG\bGH\bHU\bUP\bP to all jobs when an inter-
                      active login shell exits.
              i\bin\bnt\bte\ber\bra\bac\bct\bti\biv\bve\be_\b_c\bco\bom\bmm\bme\ben\bnt\bts\bs
                      If set, allow a word beginning with #\b# to cause that word
                      and  all remaining characters on that line to be ignored
                      in an interactive  shell  (see  C\bCO\bOM\bMM\bME\bEN\bNT\bTS\bS  above).   This
                      option is enabled by default.
              l\bli\bit\bth\bhi\bis\bst\bt If  set,  and  the c\bcm\bmd\bdh\bhi\bis\bst\bt option is enabled, multi-line
                      commands are saved to the history with embedded newlines
                      rather than using semicolon separators where possible.
              l\blo\bog\bgi\bin\bn_\b_s\bsh\bhe\bel\bll\bl
                      The  shell  sets this option if it is started as a login
                      shell (see I\bIN\bNV\bVO\bOC\bCA\bAT\bTI\bIO\bON\bN above).   The  value  may  not  be
                      changed.
              m\bma\bai\bil\blw\bwa\bar\brn\bn
                      If  set,  and  a file that b\bba\bas\bsh\bh is checking for mail has
                      been accessed since the last time it  was  checked,  the
                      message  ``The  mail in _\bm_\ba_\bi_\bl_\bf_\bi_\bl_\be has been read'' is dis-
                      played.
              n\bno\bo_\b_e\bem\bmp\bpt\bty\by_\b_c\bcm\bmd\bd_\b_c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn
                      If set, and  r\bre\bea\bad\bdl\bli\bin\bne\be  is  being  used,  b\bba\bas\bsh\bh  will  not
                      attempt to search the P\bPA\bAT\bTH\bH for possible completions when
                      completion is attempted on an empty line.
              n\bno\boc\bca\bas\bse\beg\bgl\blo\bob\bb
                      If set, b\bba\bas\bsh\bh matches  filenames  in  a  case-insensitive
                      fashion when performing pathname expansion (see P\bPa\bat\bth\bhn\bna\bam\bme\be
                      E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn above).
              n\bnu\bul\bll\blg\bgl\blo\bob\bb
                      If set, b\bba\bas\bsh\bh allows patterns which match no  files  (see
                      P\bPa\bat\bth\bhn\bna\bam\bme\be  E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn  above)  to expand to a null string,
                      rather than themselves.
              p\bpr\bro\bog\bgc\bco\bom\bmp\bp
                      If set, the programmable completion facilities (see P\bPr\bro\bo-\b-
                      g\bgr\bra\bam\bmm\bma\bab\bbl\ble\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn above) are enabled.  This option is
                      enabled by default.
              p\bpr\bro\bom\bmp\bpt\btv\bva\bar\brs\bs
                      If set, prompt strings undergo parameter expansion, com-
                      mand   substitution,  arithmetic  expansion,  and  quote
                      removal after being expanded as described  in  P\bPR\bRO\bOM\bMP\bPT\bTI\bIN\bNG\bG
                      above.  This option is enabled by default.
              r\bre\bes\bst\btr\bri\bic\bct\bte\bed\bd_\b_s\bsh\bhe\bel\bll\bl
                      The   shell  sets  this  option  if  it  is  started  in
                      restricted mode (see R\bRE\bES\bST\bTR\bRI\bIC\bCT\bTE\bED\bD S\bSH\bHE\bEL\bLL\bL 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.
              s\bsh\bhi\bif\bft\bt_\b_v\bve\ber\brb\bbo\bos\bse\be
                      If  set,  the s\bsh\bhi\bif\bft\bt builtin prints an error message when
                      the shift count exceeds the number of positional parame-
                      ters.
              s\bso\bou\bur\brc\bce\bep\bpa\bat\bth\bh
                      If set, the s\bso\bou\bur\brc\bce\be (.\b.) builtin uses the value of P\bPA\bAT\bTH\bH to
                      find the directory containing the file  supplied  as  an
                      argument.  This option is enabled by default.
              x\bxp\bpg\bg_\b_e\bec\bch\bho\bo
                      If   set,  the  e\bec\bch\bho\bo  builtin  expands  backslash-escape
                      sequences by default.
       s\bsu\bus\bsp\bpe\ben\bnd\bd [-\b-f\bf]
              Suspend the execution of this shell until it receives a  S\bSI\bIG\bGC\bCO\bON\bNT\bT
              signal.   The  -\b-f\bf option says not to complain if this is a login
              shell; just suspend anyway.  The return status is 0  unless  the
              shell is a login shell and -\b-f\bf is not supplied, or if job control
              is not enabled.
       t\bte\bes\bst\bt _\be_\bx_\bp_\br
       [\b[ _\be_\bx_\bp_\br ]\b]
              Return a status of 0 or 1 depending on  the  evaluation  of  the
              conditional  expression _\be_\bx_\bp_\br.  Each operator and operand must be
              a separate argument.  Expressions are composed of the  primaries
              described above under C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS.

              Expressions  may  be  combined  using  the  following operators,
              listed in decreasing order of precedence.
              !\b! _\be_\bx_\bp_\br True if _\be_\bx_\bp_\br is false.
              (\b( _\be_\bx_\bp_\br )\b)
                     Returns the value of _\be_\bx_\bp_\br.  This may be used to  override
                     the normal precedence of operators.
              _\be_\bx_\bp_\br_\b1 -a\ba _\be_\bx_\bp_\br_\b2
                     True if both _\be_\bx_\bp_\br_\b1 and _\be_\bx_\bp_\br_\b2 are true.
              _\be_\bx_\bp_\br_\b1 -o\bo _\be_\bx_\bp_\br_\b2
                     True if either _\be_\bx_\bp_\br_\b1 or _\be_\bx_\bp_\br_\b2 is true.

              t\bte\bes\bst\bt and [\b[ 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 !\b!, 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 C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS,  the  expression  is
                     true if the unary test is true.  If the first argument is
                     not a valid unary conditional operator, the expression is
                     false.
              3 arguments
                     If  the  second argument is one of the binary conditional
                     operators listed above under C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS, the
                     result of the expression is the result of the binary test
                     using the first and third arguments as operands.  If  the
                     first  argument  is  !\b!,  the value is the negation of the
                     two-argument test using the second and  third  arguments.
                     If the first argument is exactly (\b( and the third argument
                     is exactly )\b), the result is the one-argument test of  the
                     second  argument.   Otherwise,  the  expression is false.
                     The -\b-a\ba and -\b-o\bo operators are considered  binary  operators
                     in this case.
              4 arguments
                     If the first argument is !\b!, 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.

       t\bti\bim\bme\bes\bs  Print the accumulated user and system times for  the  shell  and
              for processes run from the shell.  The return status is 0.

       t\btr\bra\bap\bp [-\b-l\blp\bp] [[_\ba_\br_\bg] _\bs_\bi_\bg_\bs_\bp_\be_\bc ...]
              The  command  _\ba_\br_\bg  is  to  be  read  and executed when the shell
              receives signal(s) _\bs_\bi_\bg_\bs_\bp_\be_\bc.  If _\ba_\br_\bg is absent (and  there  is  a
              single  _\bs_\bi_\bg_\bs_\bp_\be_\bc)  or  -\b-,  each  specified signal is reset to its
              original disposition (the value it  had  upon  entrance  to  the
              shell).   If _\ba_\br_\bg is the null string the signal specified by each
              _\bs_\bi_\bg_\bs_\bp_\be_\bc is ignored by the shell and by the commands it  invokes.
              If  _\ba_\br_\bg  is  not present and -\b-p\bp has been supplied, then the trap
              commands associated with each  _\bs_\bi_\bg_\bs_\bp_\be_\bc  are  displayed.   If  no
              arguments  are  supplied or if only -\b-p\bp is given, t\btr\bra\bap\bp prints the
              list of commands associated with each  signal.   The  -\b-l\bl  option
              causes  the shell to print a list of signal names and their cor-
              responding numbers.   Each  _\bs_\bi_\bg_\bs_\bp_\be_\bc  is  either  a  signal  name
              defined  in  <_\bs_\bi_\bg_\bn_\ba_\bl_\b._\bh>,  or  a signal number.  Signal names are
              case insensitive and the SIG prefix is optional.  If  a  _\bs_\bi_\bg_\bs_\bp_\be_\bc
              is  E\bEX\bXI\bIT\bT (0) the command _\ba_\br_\bg is executed on exit from the shell.
              If a _\bs_\bi_\bg_\bs_\bp_\be_\bc is D\bDE\bEB\bBU\bUG\bG, the command _\ba_\br_\bg is executed before  every
              _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd, _\bf_\bo_\br command, _\bc_\ba_\bs_\be command, _\bs_\be_\bl_\be_\bc_\bt command, every
              arithmetic _\bf_\bo_\br command, and before the first command executes in
              a  shell  function  (see  S\bSH\bHE\bEL\bLL\bL  G\bGR\bRA\bAM\bMM\bMA\bAR\bR  above).   Refer to the
              description of the e\bex\bxt\btd\bde\beb\bbu\bug\bg option  to  the  s\bsh\bho\bop\bpt\bt  builtin  for
              details  of  its effect on the D\bDE\bEB\bBU\bUG\bG trap.  If a _\bs_\bi_\bg_\bs_\bp_\be_\bc is E\bER\bRR\bR,
              the command _\ba_\br_\bg is executed whenever  a  simple  command  has  a
              non-zero  exit status, subject to the following conditions.  The
              E\bER\bRR\bR trap is not executed if the failed command is  part  of  the
              command  list  immediately  following  a w\bwh\bhi\bil\ble\be or u\bun\bnt\bti\bil\bl keyword,
              part of the test in an _\bi_\bf statement, part of a &\b&&\b& or |\b||\b| list, or
              if  the  command's  return value is being inverted via !\b!.  These
              are the same conditions obeyed by  the  e\ber\brr\bre\bex\bxi\bit\bt  option.   If  a
              _\bs_\bi_\bg_\bs_\bp_\be_\bc is R\bRE\bET\bTU\bUR\bRN\bN, the command _\ba_\br_\bg is executed each time a shell
              function or a script executed with the .\b. or s\bso\bou\bur\brc\bce\be builtins fin-
              ishes executing.  Signals ignored upon entry to the shell cannot
              be trapped or reset.  Trapped signals are reset to their  origi-
              nal  values  in  a child process when it is created.  The return
              status is false  if  any  _\bs_\bi_\bg_\bs_\bp_\be_\bc  is  invalid;  otherwise  t\btr\bra\bap\bp
              returns true.

       t\bty\byp\bpe\be [-\b-a\baf\bft\btp\bpP\bP] _\bn_\ba_\bm_\be [_\bn_\ba_\bm_\be ...]
              With  no options, indicate how each _\bn_\ba_\bm_\be would be interpreted if
              used as a command name.  If the -\b-t\bt option is used, t\bty\byp\bpe\be prints a
              string  which  is  one  of _\ba_\bl_\bi_\ba_\bs, _\bk_\be_\by_\bw_\bo_\br_\bd, _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn, _\bb_\bu_\bi_\bl_\bt_\bi_\bn, or
              _\bf_\bi_\bl_\be if  _\bn_\ba_\bm_\be  is  an  alias,  shell  reserved  word,  function,
              builtin,  or disk file, respectively.  If the _\bn_\ba_\bm_\be is not found,
              then nothing  is  printed,  and  an  exit  status  of  false  is
              returned.   If  the  -\b-p\bp  option is used, t\bty\byp\bpe\be either returns the
              name of the disk file that would be executed if _\bn_\ba_\bm_\be were speci-
              fied as a command name, or nothing if ``type -t name'' would not
              return _\bf_\bi_\bl_\be.  The -\b-P\bP option forces a P\bPA\bAT\bTH\bH search for each  _\bn_\ba_\bm_\be,
              even if ``type -t name'' would not return _\bf_\bi_\bl_\be.  If a command is
              hashed, -\b-p\bp and -\b-P\bP print the hashed value,  not  necessarily  the
              file that appears first in P\bPA\bAT\bTH\bH.  If the -\b-a\ba option is used, t\bty\byp\bpe\be
              prints all of the places that contain an executable named  _\bn_\ba_\bm_\be.
              This  includes  aliases  and  functions,  if  and only if the -\b-p\bp
              option is not also used.  The table of hashed  commands  is  not
              consulted  when  using -\b-a\ba.  The -\b-f\bf option suppresses shell func-
              tion lookup, as with the c\bco\bom\bmm\bma\ban\bnd\bd builtin.  t\bty\byp\bpe\be returns true  if
              any of the arguments are found, false if none are found.

       u\bul\bli\bim\bmi\bit\bt [-\b-S\bSH\bHa\bac\bcd\bdf\bfl\blm\bmn\bnp\bps\bst\btu\buv\bv [_\bl_\bi_\bm_\bi_\bt]]
              Provides  control  over the resources available to the shell and
              to processes started by it, on systems that allow such  control.
              The -\b-H\bH and -\b-S\bS options specify that the hard or soft limit is set
              for the given resource.  A hard limit cannot be  increased  once
              it  is set; a soft limit may be increased up to the value of the
              hard limit.  If neither -\b-H\bH nor -\b-S\bS is specified,  both  the  soft
              and  hard limits are set.  The value of _\bl_\bi_\bm_\bi_\bt can be a number in
              the unit specified for the resource or one of the special values
              h\bha\bar\brd\bd,  s\bso\bof\bft\bt,  or  u\bun\bnl\bli\bim\bmi\bit\bte\bed\bd,  which  stand  for the current hard
              limit, the current soft limit, and no limit,  respectively.   If
              _\bl_\bi_\bm_\bi_\bt  is  omitted,  the  current value of the soft limit of the
              resource is printed, unless the -\b-H\bH option is given.   When  more
              than  one  resource  is  specified,  the limit name and unit are
              printed before the value.  Other options are interpreted as fol-
              lows:
              -\b-a\ba     All current limits are reported
              -\b-c\bc     The maximum size of core files created
              -\b-d\bd     The maximum size of a process's data segment
              -\b-f\bf     The maximum size of files created by the shell
              -\b-l\bl     The maximum size that may be locked into memory
              -\b-m\bm     The maximum resident set size
              -\b-n\bn     The maximum number of open file descriptors (most systems
                     do not allow this value to be set)
              -\b-p\bp     The pipe size in 512-byte blocks (this may not be set)
              -\b-s\bs     The maximum stack size
              -\b-t\bt     The maximum amount of cpu time in seconds
              -\b-u\bu     The maximum number of processes  available  to  a  single
                     user
              -\b-v\bv     The  maximum  amount  of  virtual memory available to the
                     shell

              If _\bl_\bi_\bm_\bi_\bt is given, it is the new value of the specified resource
              (the -\b-a\ba option is display only).  If no option is given, then -\b-f\bf
              is assumed.  Values are in 1024-byte increments, except for  -\b-t\bt,
              which  is  in seconds, -\b-p\bp, which is in units of 512-byte blocks,
              and -\b-n\bn and -\b-u\bu, which are unscaled values.  The return status  is
              0  unless an invalid option or argument is supplied, or an error
              occurs while setting a new limit.

       u\bum\bma\bas\bsk\bk [-\b-p\bp] [-\b-S\bS] [_\bm_\bo_\bd_\be]
              The user file-creation mask is set to _\bm_\bo_\bd_\be.  If _\bm_\bo_\bd_\be 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
              _\bc_\bh_\bm_\bo_\bd(1).   If _\bm_\bo_\bd_\be is omitted, the current value of the mask is
              printed.  The -\b-S\bS option causes the mask to be  printed  in  sym-
              bolic  form;  the  default output is an octal number.  If the -\b-p\bp
              option is supplied, and _\bm_\bo_\bd_\be 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 _\bm_\bo_\bd_\be  argument  was  supplied,
              and false otherwise.

       u\bun\bna\bal\bli\bia\bas\bs [-a\ba] [_\bn_\ba_\bm_\be ...]
              Remove  each  _\bn_\ba_\bm_\be  from  the list of defined aliases.  If -\b-a\ba is
              supplied, all alias definitions are removed.  The  return  value
              is true unless a supplied _\bn_\ba_\bm_\be is not a defined alias.

       u\bun\bns\bse\bet\bt [-f\bfv\bv] [_\bn_\ba_\bm_\be ...]
              For  each  _\bn_\ba_\bm_\be,  remove the corresponding variable or function.
              If no options are supplied, or the -\b-v\bv option is given, each _\bn_\ba_\bm_\be
              refers  to  a  shell  variable.   Read-only variables may not be
              unset.  If -\b-f\bf is specifed, each _\bn_\ba_\bm_\be refers to a shell function,
              and  the function definition is removed.  Each unset variable or
              function is removed from the environment  passed  to  subsequent
              commands.  If any of R\bRA\bAN\bND\bDO\bOM\bM, S\bSE\bEC\bCO\bON\bND\bDS\bS, L\bLI\bIN\bNE\bEN\bNO\bO, H\bHI\bIS\bST\bTC\bCM\bMD\bD, F\bFU\bUN\bNC\bCN\bNA\bAM\bME\bE,
              G\bGR\bRO\bOU\bUP\bPS\bS, or D\bDI\bIR\bRS\bST\bTA\bAC\bCK\bK are unset, they lose their  special  proper-
              ties,  even  if they are subsequently reset.  The exit status is
              true unless a _\bn_\ba_\bm_\be is readonly.

       w\bwa\bai\bit\bt [_\bn]
              Wait for the specified process and return its  termination  sta-
              tus.   _\bn  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  _\bn  is not given, all currently active child processes
              are waited for, and the return status is zero.  If _\bn specifies a
              non-existent  process  or job, the return status is 127.  Other-
              wise, the return status is the exit status of the  last  process
              or job waited for.

R\bRE\bES\bST\bTR\bRI\bIC\bCT\bTE\bED\bD S\bSH\bHE\bEL\bLL\bL
       If b\bba\bas\bsh\bh is started with the name r\brb\bba\bas\bsh\bh, or the -\b-r\br 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 b\bba\bas\bsh\bh with the exception that the  following  are
       disallowed or not performed:

       +\bo      changing directories with c\bcd\bd

       +\bo      setting or unsetting the values of S\bSH\bHE\bEL\bLL\bL, P\bPA\bAT\bTH\bH, E\bEN\bNV\bV, or B\bBA\bAS\bSH\bH_\b_E\bEN\bNV\bV

       +\bo      specifying command names containing /\b/

       +\bo      specifying a file name containing a /\b/ as an argument  to  the  .\b.
              builtin command

       +\bo      Specifying  a  filename containing a slash as an argument to the
              -\b-p\bp option to the h\bha\bas\bsh\bh builtin command

       +\bo      importing function definitions from  the  shell  environment  at
              startup

       +\bo      parsing  the  value  of  S\bSH\bHE\bEL\bLL\bLO\bOP\bPT\bTS\bS from the shell environment at
              startup

       +\bo      redirecting output using the >, >|, <>, >&, &>, and >>  redirec-
              tion operators

       +\bo      using the e\bex\bxe\bec\bc builtin command to replace the shell with another
              command

       +\bo      adding or deleting builtin commands with the -\b-f\bf and  -\b-d\bd  options
              to the e\ben\bna\bab\bbl\ble\be builtin command

       +\bo      Using  the  e\ben\bna\bab\bbl\ble\be  builtin  command  to  enable  disabled shell
              builtins

       +\bo      specifying the -\b-p\bp option to the c\bco\bom\bmm\bma\ban\bnd\bd builtin command

       +\bo      turning off restricted mode with s\bse\bet\bt +\b+r\br or s\bse\bet\bt +\b+o\bo r\bre\bes\bst\btr\bri\bic\bct\bte\bed\bd.

       These restrictions are enforced after any startup files are read.

       When a command that is found to be a shell script is executed (see C\bCO\bOM\bM-\b-
       M\bMA\bAN\bND\bD  E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN  above),  r\brb\bba\bas\bsh\bh turns off any restrictions in the shell
       spawned to execute the script.

S\bSE\bEE\bE A\bAL\bLS\bSO\bO
       _\bB_\ba_\bs_\bh _\bR_\be_\bf_\be_\br_\be_\bn_\bc_\be _\bM_\ba_\bn_\bu_\ba_\bl, Brian Fox and Chet Ramey
       _\bT_\bh_\be _\bG_\bn_\bu _\bR_\be_\ba_\bd_\bl_\bi_\bn_\be _\bL_\bi_\bb_\br_\ba_\br_\by, Brian Fox and Chet Ramey
       _\bT_\bh_\be _\bG_\bn_\bu _\bH_\bi_\bs_\bt_\bo_\br_\by _\bL_\bi_\bb_\br_\ba_\br_\by, Brian Fox and Chet Ramey
       _\bP_\bo_\br_\bt_\ba_\bb_\bl_\be _\bO_\bp_\be_\br_\ba_\bt_\bi_\bn_\bg _\bS_\by_\bs_\bt_\be_\bm _\bI_\bn_\bt_\be_\br_\bf_\ba_\bc_\be _\b(_\bP_\bO_\bS_\bI_\bX_\b) _\bP_\ba_\br_\bt _\b2_\b:  _\bS_\bh_\be_\bl_\bl  _\ba_\bn_\bd  _\bU_\bt_\bi_\bl_\bi_\b-
       _\bt_\bi_\be_\bs, IEEE
       _\bs_\bh(1), _\bk_\bs_\bh(1), _\bc_\bs_\bh(1)
       _\be_\bm_\ba_\bc_\bs(1), _\bv_\bi(1)
       _\br_\be_\ba_\bd_\bl_\bi_\bn_\be(3)

F\bFI\bIL\bLE\bES\bS
       _\b/_\bb_\bi_\bn_\b/_\bb_\ba_\bs_\bh
              The b\bba\bas\bsh\bh executable
       _\b/_\be_\bt_\bc_\b/_\bp_\br_\bo_\bf_\bi_\bl_\be
              The systemwide initialization file, executed for login shells
       _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bp_\br_\bo_\bf_\bi_\bl_\be
              The personal initialization file, executed for login shells
       _\b~_\b/_\b._\bb_\ba_\bs_\bh_\br_\bc
              The individual per-interactive-shell startup file
       _\b~_\b/_\b._\bb_\ba_\bs_\bh_\b__\bl_\bo_\bg_\bo_\bu_\bt
              The individual login shell cleanup file, executed when  a  login
              shell exits
       _\b~_\b/_\b._\bi_\bn_\bp_\bu_\bt_\br_\bc
              Individual _\br_\be_\ba_\bd_\bl_\bi_\bn_\be initialization file

A\bAU\bUT\bTH\bHO\bOR\bRS\bS
       Brian Fox, Free Software Foundation
       bfox@gnu.org

       Chet Ramey, Case Western Reserve University
       chet@po.CWRU.Edu

B\bBU\bUG\bG R\bRE\bEP\bPO\bOR\bRT\bTS\bS
       If you find a bug in b\bba\bas\bsh\bh,\b, 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  b\bba\bas\bsh\bh.   The  latest  version  is  always  available  from
       _\bf_\bt_\bp_\b:_\b/_\b/_\bf_\bt_\bp_\b._\bg_\bn_\bu_\b._\bo_\br_\bg_\b/_\bp_\bu_\bb_\b/_\bb_\ba_\bs_\bh_\b/.

       Once you have determined that a bug actually exists,  use  the  _\bb_\ba_\bs_\bh_\bb_\bu_\bg
       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  _\bb_\bu_\bg_\b-_\bb_\ba_\bs_\bh_\b@_\bg_\bn_\bu_\b._\bo_\br_\bg  or  posted  to  the  Usenet newsgroup
       g\bgn\bnu\bu.\b.b\bba\bas\bsh\bh.\b.b\bbu\bug\bg.

       ALL bug reports should include:

       The version number of b\bba\bas\bsh\bh
       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

       _\bb_\ba_\bs_\bh_\bb_\bu_\bg 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 _\bc_\bh_\be_\bt_\b@_\bp_\bo_\b._\bC_\bW_\bR_\bU_\b._\bE_\bd_\bu.

B\bBU\bUG\bGS\bS
       It's too big and too slow.

       There are some subtle differences between b\bba\bas\bsh\bh and traditional versions
       of s\bsh\bh, mostly because of the P\bPO\bOS\bSI\bIX\bX 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  pro-
       cess is stopped, the shell immediately executes the next command in the
       sequence.  It suffices to place the sequence of commands between paren-
       theses to force it into a subshell, which may be stopped as a unit.

       Commands  inside  of  $\b$(\b(...)\b)  command substitution are not parsed until
       substitution is attempted.  This will delay error reporting until  some
       time after the command is entered.  For example, unmatched parentheses,
       even inside shell comments, will result in  error  messages  while  the
       construct is being read.

       Array variables may not (yet) be exported.



GNU Bash-3.0                     2004 June 26                          BASH(1)