Imported from ../bash-4.0.tar.gz.

[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) 1989-2009 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 Shell and
       Utilities portion  of  the  IEEE  POSIX  specification  (IEEE  Standard
       1003.1).  B\bBa\bas\bsh\bh can be configured to be POSIX-conformant by default.

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 output.  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 (por-
              table 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 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\bn-\b-
       s\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 with its standard input
       connected  to a a network connection, as if by the remote shell daemon,
       usually _\br_\bs_\bh_\bd, or the secure shell daemon _\bs_\bs_\bh_\bd.  If b\bba\bas\bsh\bh  determines  it
       is  being  run  in  this  fashion,  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|&\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 one of
       the control operators |\b| or |\b|&\b&.  The format for a pipeline is:

              [t\bti\bim\bme\be [-\b-p\bp]] [ ! ] _\bc_\bo_\bm_\bm_\ba_\bn_\bd [ [|\b|||\b|&\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).  If |\b|&\b& is used,
       the standard error of _\bc_\bo_\bm_\bm_\ba_\bn_\bd is connected to _\bc_\bo_\bm_\bm_\ba_\bn_\bd_\b2's standard input
       through the pipe; it is shorthand for 2\b2>\b>&\b&1\b1 |\b|.  This implicit  redirect-
       ion of the standard error is performed after any redirections specified
       by the command.

       The return status of a pipeline is the exit status of the last command,
       unless  the  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&, 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.

       AND and OR lists are sequences of one of more  pipelines  separated  by
       the  &\b&&\b&  and  |\b||\b| control operators, respectively.  AND and OR lists are
       executed with left associativity.  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 or another shell
              metacharacter.

       ((_\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.  If the shell
              option n\bno\boc\bca\bas\bse\bem\bma\bat\btc\bch\bh is enabled, the match  is  performed  without
              regard  to  the case of alphabetic characters.  The return value
              is 0 if the string matches (=\b==\b=) or does not match (!\b!=\b=) the  pat-
              tern, 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\bem\bma\bat\btc\bch\bh
              is enabled, the match is performed without regard to the case of
              alphabetic characters.  Any part of the pattern may be quoted to
              force  it  to  be  matched  as  a string.  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  parenthe-
              sized subexpression.

              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 dis-
              played 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).  The _\bw_\bo_\br_\bd is
              expanded using tilde expansion, parameter  and  variable  expan-
              sion,  arithmetic  substitution,  command  substitution, process
              substitution  and  quote  removal.   Each  _\bp_\ba_\bt_\bt_\be_\br_\bn  examined  is
              expanded  using  tilde  expansion, parameter and variable expan-
              sion, arithmetic substitution, command substitution, and process
              substitution.   If  the shell option n\bno\boc\bca\bas\bse\bem\bma\bat\btc\bch\bh is enabled, the
              match is performed without regard  to  the  case  of  alphabetic
              characters.   When  a  match is found, the corresponding _\bl_\bi_\bs_\bt is
              executed.  If the ;\b;;\b; operator is used, no subsequent matches are
              attempted  after  the first pattern match.  Using ;\b;&\b& in place of
              ;\b;;\b; causes execution to continue with the  _\bl_\bi_\bs_\bt  associated  with
              the  next  set of patterns.  Using ;\b;;\b;&\b& in place of ;\b;;\b; causes the
              shell to test the next pattern list in the  statement,  if  any,
              and execute any associated _\bl_\bi_\bs_\bt on a successful match.  The exit
              status is zero if no pattern matches.  Otherwise, it is the exit
              status of the last command executed in _\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.

   C\bCo\bop\bpr\bro\boc\bce\bes\bss\bse\bes\bs
       A _\bc_\bo_\bp_\br_\bo_\bc_\be_\bs_\bs is a shell command preceded by the c\bco\bop\bpr\bro\boc\bc reserved word.  A
       coprocess is executed asynchronously in a subshell, as if  the  command
       had  been  terminated  with the &\b& control operator, with a two-way pipe
       established between the executing shell and the coprocess.

       The format for a coprocess is:

              c\bco\bop\bpr\bro\boc\bc [_\bN_\bA_\bM_\bE] _\bc_\bo_\bm_\bm_\ba_\bn_\bd [_\br_\be_\bd_\bi_\br_\be_\bc_\bt_\bi_\bo_\bn_\bs]

       This creates a coprocess named _\bN_\bA_\bM_\bE.  If  _\bN_\bA_\bM_\bE  is  not  supplied,  the
       default name is _\bC_\bO_\bP_\bR_\bO_\bC.  _\bN_\bA_\bM_\bE must not be supplied if _\bc_\bo_\bm_\bm_\ba_\bn_\bd is a _\bs_\bi_\bm_\b-
       _\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd (see above); otherwise, it is interpreted as the first word
       of  the simple command.  When the coproc is executed, the shell creates
       an array variable (see A\bAr\brr\bra\bay\bys\bs below) named _\bN_\bA_\bM_\bE in the context  of  the
       executing  shell.   The  standard  output of _\bc_\bo_\bm_\bm_\ba_\bn_\bd is connected via a
       pipe to a file  descriptor  in  the  executing  shell,  and  that  file
       descriptor  is  assigned  to _\bN_\bA_\bM_\bE[0].  The standard input of _\bc_\bo_\bm_\bm_\ba_\bn_\bd is
       connected via a pipe to a file descriptor in the executing  shell,  and
       that  file descriptor is assigned to _\bN_\bA_\bM_\bE[1].  This pipe is established
       before any redirections  specified  by  the  command  (see  R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN
       below).   The  file  descriptors  can be utilized as arguments to shell
       commands and redirections using standard word expansions.  The  process
       id  of  the  shell spawned to execute the coprocess is available as the
       value of the variable _\bN_\bA_\bM_\bE_PID.  The w\bwa\bai\bit\bt builtin command may  be  used
       to wait for the coprocess to terminate.

       The return status of a coprocess is the exit status of _\bc_\bo_\bm_\bm_\ba_\bn_\bd.

   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 (see  H\bHI\bIS\bS-\b-
       T\bTO\bOR\bRY\bY E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN below), the _\bh_\bi_\bs_\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`,  \\b\,  and,
       when  history  expansion  is enabled, !\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 backslash.  If enabled, history expansion
       will be performed unless an !\b!  appearing in double  quotes  is  escaped
       using a backslash.  The backslash preceding the !\b!  is not removed.

       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 specified 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.

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

   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 exit status of the most recently  executed  fore-
              ground 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 pathname  used  to  invoke
              the  shell or shell script being executed as passed in the envi-
              ronment or argument list.  Subsequently,  expands  to  the  last
              argument  to the previous command, after expansion.  Also set to
              the full pathname used  to  invoke  each  command  executed  and
              placed in the environment exported to that command.  When check-
              ing mail, this parameter holds the name of the  mail  file  cur-
              rently being checked.

   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\bHP\bPI\bID\bD
              Expands to the process id of the  current  b\bba\bas\bsh\bh  process.   This
              differs  from  $\b$$\b$ under certain circumstances, such as subshells
              that do not require b\bba\bas\bsh\bh to be re-initialized.
       B\bBA\bAS\bSH\bH_\b_A\bAL\bLI\bIA\bAS\bSE\bES\bS
              An associative array variable whose members  correspond  to  the
              internal list of aliases as maintained by the a\bal\bli\bia\bas\bs builtin Ele-
              ments added to this array appear in the  alias  list;  unsetting
              array  elements cause aliases to be removed from the alias list.
       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 b\bba\bas\bsh\bh 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.  The shell sets B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGC\bC only when in
              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)
       B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGV\bV
              An  array  variable containing all of the parameters in the cur-
              rent b\bba\bas\bsh\bh 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.  The
              shell sets B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGV\bV only when in 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)
       B\bBA\bAS\bSH\bH_\b_C\bCM\bMD\bDS\bS
              An associative array variable whose members  correspond  to  the
              internal  hash  table  of  commands  as  maintained  by the h\bha\bas\bsh\bh
              builtin.  Elements added to this array appear in the hash table;
              unsetting  array  elements cause commands to be removed from the
              hash table.
       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]}\b} was called (or  $\b${\b{B\bBA\bAS\bSH\bH_\b_L\bLI\bIN\bNE\bEN\bNO\bO[\b[_\b$_\bi_\b-_\b1]\b]}\b}  if  refer-
              enced  within another shell function).  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]}\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_K\bKE\bEY\bY
              The key (or final key of a key sequence) used to invoke the cur-
              rent completion function.

       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_T\bTY\bYP\bPE\bE
              Set to an integer value corresponding to the type of  completion
              attempted  that  caused a completion function to be called: _\bT_\bA_\bB,
              for normal completion, _\b?, for listing completions after  succes-
              sive  tabs,  _\b!, for listing alternatives on partial word comple-
              tion, _\b@, to list completions if the word is not  unmodified,  or
              _\b%,  for  menu  completion.   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.  The words are  split  on
              shell  metacharacters  as  the shell parser would separate them.
              This variable is available only in shell  functions  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\be-\b-
              t\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, by removing the oldest entries, 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.  This uses
              the history comment character  to  distinguish  timestamps  from
              other history lines.
       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\bPR\bRO\bOM\bMP\bPT\bT_\b_D\bDI\bIR\bRT\bTR\bRI\bIM\bM
              If  set  to a number greater than zero, the value is used as the
              number of trailing directory components to retain when expanding
              the  \\b\w\bw  a\ban\bnd\bd  \\b\W\bW  p\bpr\bro\bom\bmp\bpt\bt  s\bst\btr\bri\bin\bng\bg  e\bes\bsc\bca\bap\bpe\bes\bs (\b(s\bse\bee\be P\bPR\bRO\bOM\bMP\bPT\bTI\bIN\bNG\bG below).
              Characters removed are replaced with an ellipsis.
       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.

       T\bTM\bMP\bPD\bDI\bIR\bR If  set, B\bBa\bas\bsh\bh uses its value as the name of a directory in which
              B\bBa\bas\bsh\bh creates temporary files for the shell's use.

       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%_\bs_\bt_\br_\bi_\bn_\bg 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 indexed and associative array  variables.
       Any  variable may be used as an indexed 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 con-
       tiguously.  Indexed arrays are  referenced  using  integers  (including
       arithmetic  expressions)   and  are  zero-based; associative arrays are
       referenced using arbitrary strings.

       An indexed 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 indexed 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.

       Associative arrays are created using d\bde\bec\bcl\bla\bar\bre\be -\b-A\bA _\bn_\ba_\bm_\be.

       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.   Indexed  array assignments do not require the bracket
       and subscript.  When assigning  to  indexed  arrays,  if  the  optional
       brackets  and subscript are supplied, that index is assigned to; other-
       wise the index of the element assigned is the last index assigned to by
       the statement plus one.  Indexing starts at zero.

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

       This  syntax is also accepted by the 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 the array with a subscript of 0.

       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.  Care must be  taken  to
       avoid unwanted side effects caused by filename generation.  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 indexed array and a -\b-A\bA  option  to  specify  an  associative
       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 assign-
       ments.

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[.\b..\b._\bi_\bn_\bc_\br]\b]}\b}, where _\bx and _\by  are
       either  integers or single characters, and _\bi_\bn_\bc_\br, an optional increment,
       is an integer.  When integers are supplied, the expression  expands  to
       each  number between _\bx and _\by, inclusive.  Supplied integers may be pre-
       fixed with _\b0 to force each term to have the same width.  When either  _\bx
       or  _\by  begins  with  a  zero, the shell attempts to force all generated
       terms to contain the same number of digits, zero-padding  where  neces-
       sary.   When  characters  are  supplied, the expression expands to each
       character lexicographically between _\bx and _\by, inclusive.  Note that both
       _\bx  and  _\by must be of the same type.  When the increment is supplied, it
       is used as the difference between each term.  The default increment  is
       1 or -1 as appropriate.

       Brace expansion is performed before any other expansions, and any char-
       acters special to other expansions are preserved in the result.  It  is
       strictly  textual.  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 the first =\b=.  In these cases, tilde expansion is
       also performed.  Consequently, one may use file names  with  tildes  in
       assignments  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  parameter
       expansion.

       ${_\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, using the forms documented
       below, b\bba\bas\bsh\bh tests for a parameter that is unset or null.  Omitting  the
       colon results in a test only for a parameter 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 indexed array name sub-
              scripted  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]}.  A negative _\bo_\bf_\bf_\bs_\be_\bt is
              taken  relative  to  one  greater  than the maximum index of the
              specified array.  Substring expansion applied to an  associative
              array  produces  undefined results.  Note that a negative offset
              must be separated from the colon by at least one space to  avoid
              being  confused  with  the  :- expansion.  Substring indexing is
              zero-based unless the positional parameters are used,  in  which
              case  the  indexing starts at 1 by default.  If _\bo_\bf_\bf_\bs_\be_\bt is 0, and
              the positional parameters are used, $\b$0\b0 is prefixed to the  list.

       ${!\b!_\bp_\br_\be_\bf_\bi_\bx*\b*}
       ${!\b!_\bp_\br_\be_\bf_\bi_\bx@\b@}
              N\bNa\bam\bme\bes\bs  m\bma\bat\btc\bch\bhi\bin\bng\bg p\bpr\bre\bef\bfi\bix\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.  When _\b@ is used and the expansion appears
              within double quotes, each variable name expands to  a  separate
              word.

       ${!\b!_\bn_\ba_\bm_\be[_\b@]}
       ${!\b!_\bn_\ba_\bm_\be[_\b*]}
              L\bLi\bis\bst\bt  o\bof\bf  a\bar\brr\bra\bay\by  k\bke\bey\bys\bs.\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}
              P\bPa\bar\bra\bam\bme\bet\bte\ber\br  l\ble\ben\bng\bgt\bth\bh.\b.   The  length  in  characters of the value of
              _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is substituted.  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_\b-
              _\bt_\be_\br is an array name subscripted by *\b* or @\b@,  the  value  substi-
              tuted 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}
              R\bRe\bem\bmo\bov\bve\be m\bma\bat\btc\bch\bhi\bin\bng\bg p\bpr\bre\bef\bfi\bix\bx p\bpa\bat\btt\bte\ber\brn\bn.\b.  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 pat-
              tern (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 parame-
              ter in turn, and the expansion is the resultant list.  If _\bp_\ba_\br_\ba_\bm_\b-
              _\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}
              R\bRe\bem\bmo\bov\bve\be m\bma\bat\btc\bch\bhi\bin\bng\bg s\bsu\buf\bff\bfi\bix\bx p\bpa\bat\btt\bte\ber\brn\bn.\b.  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  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 posi-
              tional 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}
              P\bPa\bat\btt\bte\ber\brn\bn s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn.\b.  The _\bp_\ba_\bt_\bt_\be_\br_\bn is expanded to produce a pat-
              tern just as in pathname expansion.  _\bP_\ba_\br_\ba_\bm_\be_\bt_\be_\br is  expanded  and
              the  longest match of _\bp_\ba_\bt_\bt_\be_\br_\bn against its value is replaced with
              _\bs_\bt_\br_\bi_\bn_\bg.  If _\bp_\ba_\bt_\bt_\be_\br_\bn begins with /\b/, all matches  of  _\bp_\ba_\bt_\bt_\be_\br_\bn  are
              replaced   with  _\bs_\bt_\br_\bi_\bn_\bg.   Normally  only  the  first  match  is
              replaced.  If _\bp_\ba_\bt_\bt_\be_\br_\bn begins with #\b#, it must match at the begin-
              ning 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/ fol-
              lowing _\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 sub-
              stitution  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 substitution
              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}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br^\b^^\b^_\bp_\ba_\bt_\bt_\be_\br_\bn}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br,\b,_\bp_\ba_\bt_\bt_\be_\br_\bn}
       ${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br,\b,,\b,_\bp_\ba_\bt_\bt_\be_\br_\bn}
              C\bCa\bas\bse\be  m\bmo\bod\bdi\bif\bfi\bic\bca\bat\bti\bio\bon\bn.\b.   This expansion modifies the case of alpha-
              betic characters in _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.  The _\bp_\ba_\bt_\bt_\be_\br_\bn is expanded to  pro-
              duce  a  pattern  just as in pathname expansion.  The ^\b^ operator
              converts lowercase letters matching _\bp_\ba_\bt_\bt_\be_\br_\bn to uppercase; the  ,\b,
              operator  converts matching uppercase letters to lowercase.  The
              ^\b^^\b^ and ,\b,,\b, expansions  convert  each  matched  character  in  the
              expanded  value;  the  ^\b^ and ,\b, expansions match and convert only
              the first character in the expanded value..  If _\bp_\ba_\bt_\bt_\be_\br_\bn is omit-
              ted,  it is treated like a ?\b?, which matches every character.  If
              _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@ or *\b*, the case modification 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 case modification 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 sequences of <\b<s\bsp\bpa\bac\bce\be>\b>, <\b<t\bta\bab\bb>\b>, and <\b<n\bne\bew\bwl\bli\bin\bne\be>\b> at  the  beginning  and
       end  of  the  results  of  the previous expansions are ignored, and any
       sequence of I\bIF\bFS\bS characters not  at  the  beginning  or  end  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 not
       enabled, 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.  When the g\bgl\blo\bob\bb-\b-
              s\bst\bta\bar\br shell option is enabled, and *\b* is used in a filename expan-
              sion  context,  two  adjacent  *\b*s  used as a single pattern will
              match all files and zero or more directories and subdirectories.
              If  followed by a /\b/, two adjacent *\b*s will match only directories
              and subdirectories.
       ?\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 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 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 re-
       direction 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.

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

   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 re-
       direction 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
       This construct allows both the standard output (file descriptor 1)  and
       the  standard  error output (file descriptor 2) to be redirected to the
       file whose name is the expansion of _\bw_\bo_\br_\bd.

       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


   A\bAp\bpp\bpe\ben\bnd\bdi\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
       This construct allows both the standard output (file descriptor 1)  and
       the  standard  error  output  (file descriptor 2) to be appended to the
       file whose name is the expansion of _\bw_\bo_\br_\bd.

       The format for appending standard output and standard error is:

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

       This is semantically equivalent to

              >\b>>\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 _\bd_\be_\bl_\bi_\bm_\bi_\bt_\be_\br (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 re-
       direction 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 and R\bRE\bET\bTU\bUR\bRN\bN traps (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) are not  inher-
       ited  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 func-
       tions inherit the D\bDE\bEB\bBU\bUG\bG and R\bRE\bET\bTU\bUR\bRN\bN traps).

       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.   A  function  definition  may  be
       deleted  using  the  -\b-f\bf  option  to the u\bun\bns\bse\bet\bt builtin.  Note that shell
       functions and variables with the same name may result in multiple iden-
       tically-named  entries  in  the environment passed to the shell's chil-
       dren.  Care should be taken in cases where this may cause a problem.

       Functions may be recursive.  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 interchangeably 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 searches for a defined shell function
       named c\bco\bom\bmm\bma\ban\bnd\bd_\b_n\bno\bot\bt_\b_f\bfo\bou\bun\bnd\bd_\b_h\bha\ban\bnd\bdl\ble\be.  If that function exists, it is invoked
       with  the  original command and the original command's arguments as its
       arguments, and the function's exit status becomes the  exit  status  of
       the  shell.  If that function is not defined, the shell prints an error
       message and returns an exit status of 127.

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

       If  this  execution fails because the file is not in executable format,
       and the file is not a directory, it is assumed to be a _\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  asynchro-
       nous commands are invoked in a subshell environment that is a duplicate
       of the shell environment, except that traps caught  by  the  shell  are
       reset to the values that the shell inherited from its parent at invoca-
       tion.  Builtin commands that are invoked as part of a pipeline are also
       executed in a subshell environment.  Changes made to the subshell envi-
       ronment cannot affect the shell's execution environment.

       Subshells spawned to execute command substitutions inherit the value of
       the  -\b-e\be  option  from  the  parent shell.  When not in posix mode, Bash
       clears the -\b-e\be option in such subshells.

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

       For the shell's purposes, a command which exits with a zero exit status
       has succeeded.  An exit status of zero indicates success.   A  non-zero
       exit  status  indicates  failure.  When a command terminates on a fatal
       signal _\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  b\bba\bas\bsh\bh is waiting for a command to complete and receives a signal for
       which a trap has been set, the trap will not be executed until the com-
       mand  completes.   When b\bba\bas\bsh\bh is waiting for an asynchronous command 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 sta-
       tus greater than 128, immediately after which the trap is executed.

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 specification (_\bj_\bo_\bb_\bs_\bp_\be_\bc).  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  example,  %\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_\b-
       _\br_\be_\bn_\bt _\bj_\bo_\bb, which is the last job stopped while it was in the  foreground
       or started in the background.  The _\bp_\br_\be_\bv_\bi_\bo_\bu_\bs _\bj_\bo_\bb may be referenced using
       %\b%-\b-.  If there is only a single job, %\b%+\b+ and %\b%-\b- can both be used to refer
       to  that  job.   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 pre-
       vious  job  with  a -\b-.  A single % (with no accompanying job specifica-
       tion) also refers to the current job.

       Simply naming a job can be used to bring it into the foreground: %\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 (or,  if  the
       c\bch\bhe\bec\bck\bkj\bjo\bob\bbs\bs  shell  option has been enabled using the s\bsh\bho\bop\bpt\bt builtin, run-
       ning), the shell prints a warning message, and, if the c\bch\bhe\bec\bck\bkj\bjo\bob\bbs\bs option
       is  enabled,  lists  the jobs and their statuses.  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 intervening command, the shell does not print another
       warning, and any 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 (uses the $\b$P\bPR\bRO\bOM\bMP\bPT\bT_\b_D\bDI\bIR\bRT\bTR\bRI\bIM\bM variable)
              \\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.
       Line editing is also used when using the -\b-e\be option to the r\bre\bea\bad\bd builtin.
       By default, the line editing commands are similar to those of emacs.  A
       vi-style line editing interface is also available.  Line editing can be
       enabled  at  any  time  using  the -\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).  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.

   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
       (without  regard  to  case).   Unrecognized variable names are ignored.
       When a variable value is read, empty or null values, "on"  (case-insen-
       sitive), and "1" are equivalent to O\bOn\bn.  All other values are equivalent
       to 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.
       b\bbi\bin\bnd\bd-\b-t\btt\bty\by-\b-s\bsp\bpe\bec\bci\bia\bal\bl-\b-c\bch\bha\bar\brs\bs (\b(O\bOn\bn)\b)
              If  set  to O\bOn\bn, readline attempts to bind the control characters
              treated specially by the kernel's terminal driver to their read-
              line equivalents.
       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-p\bpr\bre\bef\bfi\bix\bx-\b-d\bdi\bis\bsp\bpl\bla\bay\by-\b-l\ble\ben\bng\bgt\bth\bh (\b(0\b0)\b)
              The length in characters of the common prefix of a list of  pos-
              sible  completions that is displayed without modification.  When
              set to a value greater than zero, common  prefixes  longer  than
              this  value are replaced with an ellipsis when displaying possi-
              ble completions.
       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 (\b(O\bOf\bff\bf)\b)
              If set to o\bon\bn, the history code attempts to place  point  at  the
              same  location on each history line retrieved 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\bhi\bis\bst\bto\bor\bry\by-\b-s\bsi\biz\bze\be (\b(0\b0)\b)
              Set the maximum number of history entries saved in  the  history
              list.  If set to zero, the number of entries in the history list
              is not limited.
       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.
       r\bre\bev\bve\ber\brt\bt-\b-a\bal\bll\bl-\b-a\bat\bt-\b-n\bne\bew\bwl\bli\bin\bne\be (\b(O\bOf\bff\bf)\b)
              If set to o\bon\bn, readline will undo all changes  to  history  lines
              before returning when a\bac\bcc\bce\bep\bpt\bt-\b-l\bli\bin\bne\be is executed.  By default, his-
              tory lines may be modified  and  retain  individual  undo  lists
              across calls to r\bre\bea\bad\bdl\bli\bin\bne\be.
       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  com-
              pletions.

   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).
       s\bsh\bhe\bel\bll\bl-\b-f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd
              Move forward to the end of the next word.  Words  are  delimited
              by non-quoted shell metacharacters.
       s\bsh\bhe\bel\bll\bl-\b-b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd
              Move  back  to the start of the current or previous word.  Words
              are delimited by non-quoted shell metacharacters.
       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.  Once
              the argument _\bn is computed, the argument is extracted as if  the
              "!_\bn" history expansion had been specified.
       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.  The history expansion facilities are used
              to extract the last argument, as if the "!$"  history  expansion
              had been specified.
       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 $\b$V\bVI\bIS\bSU\bUA\bAL\bL,
              $\b$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.
       s\bsh\bhe\bel\bll\bl-\b-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 s\bsh\bhe\bel\bll\bl-\b-f\bfo\bor\brw\bwa\bar\brd\bd-\b-w\bwo\bor\brd\bd.
       s\bsh\bhe\bel\bll\bl-\b-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 s\bsh\bhe\bel\bll\bl-\b-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.
       d\bda\bab\bbb\bbr\bre\bev\bv-\b-e\bex\bxp\bpa\ban\bnd\bd
              Attempt menu 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 output.  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\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, and arithmetic 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 completed, 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, C\bCO\bOM\bMP\bP_\b_P\bPO\bOI\bIN\bNT\bT, C\bCO\bOM\bMP\bP_\b_K\bKE\bEY\bY, and C\bCO\bOM\bMP\bP_\b_T\bTY\bYP\bPE\bE
       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 the his-
       tory file is read, lines beginning with the history  comment  character
       followed  immediately  by a digit are interpreted as timestamps for the
       preceding history line.   These  timestamps  are  optionally  displayed
       depending  on the value of the H\bHI\bIS\bST\bTT\bTI\bIM\bME\bEF\bFO\bOR\bRM\bMA\bAT\bT variable.  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.   If the variable is set, time stamps are
       written to the history file, marked with the history comment character,
       so  they may be preserved across shell sessions.  This uses the history
       comment character to distinguish timestamps from other  history  lines.
       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\bES\bSI\bIZ\bZE\bE is not set,  no  trunca-
       tion 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).  The shell uses the history comment character to mark  his-
       tory timestamps when writing the history file.

   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.   For  example,  the  :\b:, t\btr\bru\bue\be, f\bfa\bal\bls\bse\be, and t\bte\bes\bst\bt builtins do not
       accept 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 exe-
              cuted 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_\b-
              _\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,  any  specified  _\bj_\bo_\bb_\bs_\bp_\be_\bc  was  not found or was started
              without 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-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-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-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.   When _\bs_\bh_\be_\bl_\bl_\b-_\bc_\bo_\bm_\bm_\ba_\bn_\bd is executed, the shell sets
                     the R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE_\b_L\bLI\bIN\bNE\bE variable to the contents of  the  r\bre\bea\bad\bd-\b-
                     l\bli\bin\bne\be  line  buffer and the R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE_\b_P\bPO\bOI\bIN\bNT\bT variable to the
                     current location of the insertion point.  If the executed
                     command  changes  the  value  of  R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE_\b_L\bLI\bIN\bNE\bE  or R\bRE\bEA\bAD\bD-\b-
                     L\bLI\bIN\bNE\bE_\b_P\bPO\bOI\bIN\bNT\bT, those new values will  be  reflected  in  the
                     editing state.

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

       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 _\bn is not greater than or
              equal to 1.

       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\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\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\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-E\bE] [-\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-F\bF _\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn] [-\b-C\bC _\bc_\bo_\bm_\bm_\ba_\bn_\bd]
              [-\b-X\bX _\bf_\bi_\bl_\bt_\be_\br_\bp_\ba_\bt] [-\b-P\bP _\bp_\br_\be_\bf_\bi_\bx] [-\b-S\bS _\bs_\bu_\bf_\bf_\bi_\bx] _\bn_\ba_\bm_\be [_\bn_\ba_\bm_\be _\b._\b._\b.]
       c\bco\bom\bmp\bpl\ble\bet\bte\be -\b-p\bpr\br [-\b-E\bE] [_\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  -\b-E\bE  option  indicates  that  the
              remaining options and actions should apply to ``empty''  command
              completion; that is, completion attempted on a blank line.

              The  process  of  applying  these completion specifications when
              word completion is  attempted  is  described  above  under  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 comple-
                      tions.  _\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, quoting special characters, or  suppress-
                              ing  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.
                      p\bpl\blu\bus\bsd\bdi\bir\brs\bs
                              After any matches defined by  the  compspec  are
                              generated,    directory   name   completion   is
                              attempted and  any  matches  are  added  to  the
                              results of the other actions.
              -\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\bom\bmp\bpo\bop\bpt\bt [-\b-o\bo _\bo_\bp_\bt_\bi_\bo_\bn] [+\b+o\bo _\bo_\bp_\bt_\bi_\bo_\bn] [_\bn_\ba_\bm_\be]
              Modify  completion  options  for  each  _\bn_\ba_\bm_\be  according  to  the
              _\bo_\bp_\bt_\bi_\bo_\bns, or for the currently-execution completion if  no  _\bn_\ba_\bm_\bes
              are  supplied.   If no _\bo_\bp_\bt_\bi_\bo_\bns are given, display the completion
              options for each _\bn_\ba_\bm_\be or the current completion.   The  possible
              values  of  _\bo_\bp_\bt_\bi_\bo_\bn  are  those  valid  for  the c\bco\bom\bmp\bpl\ble\bet\bte\be builtin
              described above.

       The return value is true unless  an  invalid  option  is  supplied,  an
       attempt  is  made to modify the options for a _\bn_\ba_\bm_\be for which no comple-
       tion specification exists, or an output error occurs.

       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 _\bn is not greater
              than or equal to 1.

       d\bde\bec\bcl\bla\bar\bre\be [-\b-a\baA\bAf\bfF\bFi\bil\blr\brt\btu\bux\bx] [-\b-p\bp] [_\bn_\ba_\bm_\be[=_\bv_\ba_\bl_\bu_\be] ...]
       t\bty\byp\bpe\bes\bse\bet\bt [-\b-a\baA\bAf\bfF\bFi\bil\blr\brt\btu\bux\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
              with _\bn_\ba_\bm_\be arguments, additional options are ignored.  When -\b-p\bp is
              supplied  without _\bn_\ba_\bm_\be arguments, it will display the attributes
              and values of all variables having the attributes  specified  by
              the  additional  options.  If no other options are supplied with
              -\b-p\bp, d\bde\bec\bcl\bla\bar\bre\be will display the attributes and values of all  shell
              variables.   The  -\b-f\bf  option  will restrict the display to shell
              functions.  The -\b-F\bF option inhibits the display of function defi-
              nitions;  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 dis-
              played as well.   The  -\b-F\bF  option  implies  -\b-f\bf.   The  following
              options  can  be  used  to restrict output to variables with the
              specified attribute or to give variables attributes:
              -\b-a\ba     Each _\bn_\ba_\bm_\be  is  an  indexed  array  variable  (see  A\bAr\brr\bra\bay\bys\bs
                     above).
              -\b-A\bA     Each  _\bn_\ba_\bm_\be  is  an associative 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-l\bl     When the variable is assigned  a  value,  all  upper-case
                     characters  are  converted to lower-case.  The upper-case
                     attribute is disabled.
              -\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  and  R\bRE\bET\bTU\bUR\bRN\bN  traps  from  the  calling
                     shell.   The  trace  attribute has no special meaning for
                     variables.
              -\b-u\bu     When the variable is assigned  a  value,  all  lower-case
                     characters  are  converted to upper-case.  The lower-case
                     attribute is disabled.
              -\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 exceptions that +\b+a\ba may not be used to destroy an array vari-
              able  and  +\b+r\br w\bwi\bil\bll\bl n\bno\bot\bt r\bre\bem\bmo\bov\bve\be t\bth\bhe\be r\bre\bea\bad\bdo\bon\bnl\bly\by a\bat\btt\btr\bri\bib\bbu\but\bte\be.\b.  W\bWh\bhe\ben\bn u\bus\bse\bed\bd
              i\bin\bn a\ba f\bfu\bun\bnc\bct\bti\bio\bon\bn,\b, m\bma\bak\bke\bes\bs e\bea\bac\bch\bh _\bn_\ba_\bm_\be l\blo\boc\bca\bal\bl,\b, a\bas\bs w\bwi\bit\bth\bh t\bth\bhe\be l\blo\boc\bca\bal\bl command.
              If a variable name is followed by =_\bv_\ba_\bl_\bu_\be, the value of the vari-
              able 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 readonly status for a read-
              only  variable,  an attempt is made to turn off array status for
              an array variable, or an attempt is made to display a  non-exis-
              tent function with -\b-f\bf.

       d\bdi\bir\brs\bs [\b[+\b+_\bn]\b] [\b[-\b-_\bn]\b] [\b[-\b-c\bcp\bpl\blv\bv]\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 _\bj_\bo_\bb_\bs_\bp_\be_\bc is not present, and neither -\b-a\ba  n\bno\bor\br  -\b-r\br
              i\bis\bs  s\bsu\bup\bpp\bpl\bli\bie\bed\bd,\b, t\bth\bhe\be s\bsh\bhe\bel\bll\bl'\b's\bs n\bno\bot\bti\bio\bon\bn o\bof\bf t\bth\bhe\be _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb i\bis\bs u\bus\bse\bed\bd.\b.  I\bIf\bf
              t\bth\bhe\be -\b-h\bh o\bop\bpt\bti\bio\bon\bn i\bis\bs g\bgi\biv\bve\ben\bn,\b, e\bea\bac\bch\bh _\bj_\bo_\bb_\bs_\bp_\be_\bc is not removed from the ta-
              ble,  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_\bs_\bp_\be_\bc argument restricts
              operation to running jobs.  The return value is 0 unless a  _\bj_\bo_\bb_\b-
              _\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 further output
              \\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\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\ba] [-\b-d\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 argument 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 can-
              not 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 cannot be executed.  If _\bc_\bo_\bm_\bm_\ba_\bn_\bd is not specified, any redi-
              rections take effect in the current shell, and the return status
              is  0.  If there is a redirection error, the return status is 1.

       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-l\bln\bnr\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-d\bdm\bms\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.
              -\b-d\bd     Display a short description of each _\bp_\ba_\bt_\bt_\be_\br_\bn
               -\b-m\bm    Display the description of each _\bp_\ba_\bt_\bt_\be_\br_\bn in a manpage-like
                     format
              -\b-s\bs     Display only a short usage synopsis for each _\bp_\ba_\bt_\bt_\be_\br_\bn
       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,
              marked  with  the  history  comment character.  When the history
              file is read, lines beginning with the history comment character
              followed  immediately  by  a digit are interpreted as timestamps
              for the previous history line.  The return value is 0 unless  an
              invalid  option is encountered, an error occurs while reading or
              writing the history file, an invalid _\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.

       m\bma\bap\bpf\bfi\bil\ble\be  [-\b-n\bn  _\bc_\bo_\bu_\bn_\bt]  [-\b-O\bO _\bo_\br_\bi_\bg_\bi_\bn] [-\b-s\bs _\bc_\bo_\bu_\bn_\bt] [-\b-t\bt] [-\b-u\bu _\bf_\bd] [-\b-C\bC _\bc_\ba_\bl_\bl_\bb_\ba_\bc_\bk]
       [-\b-c\bc _\bq_\bu_\ba_\bn_\bt_\bu_\bm] [_\ba_\br_\br_\ba_\by]
       r\bre\bea\bad\bda\bar\brr\bra\bay\by  [-\b-n\bn _\bc_\bo_\bu_\bn_\bt] [-\b-O\bO _\bo_\br_\bi_\bg_\bi_\bn] [-\b-s\bs _\bc_\bo_\bu_\bn_\bt] [-\b-t\bt] [-\b-u\bu _\bf_\bd] [-\b-C\bC _\bc_\ba_\bl_\bl_\bb_\ba_\bc_\bk]
       [-\b-c\bc _\bq_\bu_\ba_\bn_\bt_\bu_\bm] [_\ba_\br_\br_\ba_\by]
              Read lines from the standard input into array variable _\ba_\br_\br_\ba_\by, or
              from file descriptor _\bf_\bd if the -\b-u\bu option is supplied.  The vari-
              able  M\bMA\bAP\bPF\bFI\bIL\bLE\bE  is the default _\ba_\br_\br_\ba_\by.  Options, if supplied, have
              the following meanings:
              -\b-n\bn     Copy at most _\bc_\bo_\bu_\bn_\bt lines.  If _\bc_\bo_\bu_\bn_\bt is 0, all  lines  are
                     copied.
              -\b-O\bO     Begin  assigning  to  _\ba_\br_\br_\ba_\by at index _\bo_\br_\bi_\bg_\bi_\bn.  The default
                     index is 0.
              -\b-s\bs     Discard the first _\bc_\bo_\bu_\bn_\bt lines read.
              -\b-t\bt     Remove a trailing line from each line read.
              -\b-u\bu     Read lines from file descriptor _\bf_\bd instead of  the  stan-
                     dard input.
              -\b-C\bC     Evaluate  _\bc_\ba_\bl_\bl_\bb_\ba_\bc_\bk each time _\bq_\bu_\ba_\bn_\bt_\bu_\bm lines are read.  The
                     -\b-c\bc option specifies _\bq_\bu_\ba_\bn_\bt_\bu_\bm.
              -\b-c\bc     Specify the number of lines read  between  each  call  to
                     _\bc_\ba_\bl_\bl_\bb_\ba_\bc_\bk.

              If  -\b-C\bC  is  specified  without  -\b-c\bc, the default quantum is 5000.
              When _\bc_\ba_\bl_\bl_\bb_\ba_\bc_\bk is evaluated, it is supplied the index of the next
              array  element  to be assigned as an additional argument.  _\bc_\ba_\bl_\bl_\b-
              _\bb_\ba_\bc_\bk is evaluated after the line is read but  before  the  array
              element is assigned.

              If  not  supplied  with  an  explicit origin, m\bma\bap\bpf\bfi\bil\ble\be will clear
              _\ba_\br_\br_\ba_\by before assigning to it.

              m\bma\bap\bpf\bfi\bil\ble\be returns successfully unless an invalid option or  option
              argument is supplied, or _\ba_\br_\br_\ba_\by is invalid or unassignable.

       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-n\bn     Suppresses the normal change of directory  when  removing
                     directories  from  the  stack,  so that only the stack is
                     manipulated.
              +\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.

              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 [-\b-v\bv _\bv_\ba_\br] _\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 -\b-v\bv option causes the output to be assigned to  the  variable
              _\bv_\ba_\br rather than being printed to the standard output.

              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] [+_\bn] [-_\bn]
       p\bpu\bus\bsh\bhd\bd [-\b-n\bn] [_\bd_\bi_\br]
              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-n\bn     Suppresses  the  normal  change  of directory when adding
                     directories to the stack,  so  that  only  the  stack  is
                     manipulated.
              +\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.
              _\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-a\ba _\ba_\bn_\ba_\bm_\be] [-\b-d\bd _\bd_\be_\bl_\bi_\bm] [-\b- _\bt_\be_\bx_\bt] [-\b-n\bn _\bn_\bc_\bh_\ba_\br_\bs] [-\b-p\bp _\bp_\br_\bo_\bm_\bp_\bt] [-\b-t\bt
       _\bt_\bi_\bm_\be_\bo_\bu_\bt] [-\b-u\bu _\bf_\bd] [_\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.   Read-
                     line  uses  the  current (or default, if line editing was
                     not previously active) editing settings.
              -\b-i\bi _\bt_\be_\bx_\bt
                     If r\bre\bea\bad\bdl\bli\bin\bne\be is being used  to  read  the  line,  _\bt_\be_\bx_\bt  is
                     placed into the editing buffer before editing begins.
              -\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.  _\bt_\bi_\bm_\be_\b-
                     _\bo_\bu_\bt may be a decimal number  with  a  fractional  portion
                     following  the decimal point.  This option is only effec-
                     tive if r\bre\bea\bad\bd is reading input from a terminal,  pipe,  or
                     other  special  file;  it has no effect when reading from
                     regular files.  If _\bt_\bi_\bm_\be_\bo_\bu_\bt is 0, r\bre\bea\bad\bd returns success  if
                     input  is  available  on  the  specified file descriptor,
                     failure otherwise.  The exit status is greater  than  128
                     if the timeout is exceeded.
              -\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 (in which case the return code is
              greater than 128), 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\baA\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  indexed
              arrays;  the  -\b-A\bA  option  restricts the variables to associative
              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 variable 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 function.

       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\bCE\bEH\bHP\bPT\bT] [-\b-o\bo _\bo_\bp_\bt_\bi_\bo_\bn] [_\ba_\br_\bg ...]
       s\bse\bet\bt [+\b+a\bab\bbe\bef\bfh\bhk\bkm\bmn\bnp\bpt\btu\buv\bvx\bxB\bBC\bCE\bEH\bHP\bPT\bT] [+\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 for setting or
              resetting the currently-set variables.  Read-only variables can-
              not be reset.  In _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be, only shell variables  are  listed.
              The  output  is  sorted  according  to the current locale.  When
              options are specified, they set or unset shell attributes.   Any
              arguments  remaining after option processing are treated as val-
              ues for the positional parameters and are assigned, in order, to
              $\b$1\b1,  $\b$2\b2,  .\b..\b..\b.   $\b$_\bn.   Options,  if specified, have the following
              meanings:
              -\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 i\bif\bf statement, part of  a  command
                      executed  in  a &\b&&\b& or |\b||\b| list, any command in a pipeline
                      but the last, or if the command's return value is  being
                      inverted  via  !\b!.  Failing simple commands that are part
                      of shell functions or command lists enclosed  in  braces
                      or  parentheses  satisfying  the above conditions do not
                      cause the shell to exit.  A trap on E\bER\bRR\bR, if set, is exe-
                      cuted 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.  This also  affects  the
                              editing interface used for r\bre\bea\bad\bd -\b-e\be.
                      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  standard  to
                              match the standard (_\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.
                              This also affects the editing interface used for
                              r\bre\bea\bad\bd -\b-e\be.
                      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,
                      C\bCD\bDP\bPA\bAT\bTH\bH, and G\bGL\bLO\bOB\bBI\bIG\bGN\bNO\bOR\bRE\bE variables, if they appear in  the
                      environment,  are ignored.  If the shell is started with
                      the effective user (group) id not equal to the real user
                      (group)  id,  and  the  -\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 traps on D\bDE\bEB\bBU\bUG\bG and R\bRE\bET\bTU\bUR\bRN\bN are inherited by
                      shell functions,  command  substitutions,  and  commands
                      executed  in  a  subshell  environment.   The  D\bDE\bEB\bBU\bUG\bG and
                      R\bRE\bET\bTU\bUR\bRN\bN traps are 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:

              a\bau\but\bto\boc\bcd\bd  If  set,  a command name that is the name of a directory
                      is executed as if it were the argument to  the  c\bcd\bd  com-
                      mand.  This option is only used by interactive shells.
              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\bkj\bjo\bob\bbs\bs
                      If set, b\bba\bas\bsh\bh lists the status of any stopped and running
                      jobs  before  exiting an interactive shell.  If any jobs
                      are running, this causes the exit to be deferred until a
                      second  exit is attempted without an intervening command
                      (see J\bJO\bOB\bB C\bCO\bON\bNT\bTR\bRO\bOL\bL above).   The  shell  always  postpones
                      exiting if any jobs are stopped.
              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\bL-\b-
                      U\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.
              c\bco\bom\bmp\bpa\bat\bt3\b31\b1
                      If set, b\bba\bas\bsh\bh changes its behavior to that of version 3.1
                      with respect to quoted arguments to the conditional com-
                      mand's =~ operator.
              d\bdi\bir\brs\bsp\bpe\bel\bll\bl
                      If  set,  b\bba\bas\bsh\bh attempts spelling correction on directory
                      names during word completion if the directory name  ini-
                      tially supplied does not exist.
              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.
                      4\b4.\b.     B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGC\bC and B\bBA\bAS\bSH\bH_\b_A\bAR\bRG\bGV\bV are updated as  described
                             in their descriptions above.
                      5\b5.\b.     Function  tracing  is enabled:  command substitu-
                             tion, shell functions, and subshells invoked with
                             (\b( _\bc_\bo_\bm_\bm_\ba_\bn_\bd )\b) inherit the D\bDE\bEB\bBU\bUG\bG and R\bRE\bET\bTU\bUR\bRN\bN traps.
                      6\b6.\b.     Error  tracing is enabled:  command substitution,
                             shell functions, and  subshells  invoked  with  (\b(
                             _\bc_\bo_\bm_\bm_\ba_\bn_\bd )\b) inherit the E\bER\bRR\bRO\bOR\bR trap.
              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\bgl\blo\bob\bbs\bst\bta\bar\br
                      If set, the pattern *\b**\b* used in a filename expansion con-
                      text will match a files and zero or more directories and
                      subdirectories.  If the pattern is followed by a /\b/, only
                      directories and subdirectories match.
              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\bno\boc\bca\bas\bse\bem\bma\bat\btc\bch\bh
                      If  set,  b\bba\bas\bsh\bh  matches  patterns  in a case-insensitive
                      fashion when performing matching while executing c\bca\bas\bse\be or
                      [\b[[\b[ conditional commands.
              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.  A login shell cannot be suspended; the -\b-f\bf option can be
              used to override this and force the suspension.  The return sta-
              tus is 0 unless the shell is a login shell and -\b-f\bf  is  not  sup-
              plied, 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.   t\bte\bes\bst\bt  does  not
              accept any options, nor does it accept and ignore an argument of
              -\b--\b- as signifying the end of options.

              Expressions may  be  combined  using  the  following  operators,
              listed  in  decreasing  order  of  precedence.   The  evaluation
              depends on the number of arguments; see below.
              !\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.  The  -\b-a\ba
                     and  -\b-o\bo  operators  are  considered binary operators when
                     there are three arguments.  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.   Other-
                     wise, the expression is false.
              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 command  executed
              in  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 exe-
              cuted each time a shell function or a script executed with the .\b.
              or  s\bso\bou\bur\brc\bce\be  builtins  finishes  executing.  Signals ignored upon
              entry to the shell cannot be trapped or reset.  Trapped  signals
              that are not being ignored are reset to their original values in
              a 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
              all of the arguments are found, false if any are not found.

       u\bul\bli\bim\bmi\bit\bt [-\b-H\bHS\bST\bTa\bab\bbc\bcd\bde\bef\bfi\bil\blm\bmn\bnp\bpq\bqr\brs\bst\btu\buv\bvx\bx [_\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  by  a
              non-root  user  once it is set; a soft limit may be increased up
              to the value of the hard limit.  If neither -\b-H\bH nor -\b-S\bS is  speci-
              fied, 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 inter-
              preted as follows:
              -\b-a\ba     All current limits are reported
              -\b-b\bb     The maximum socket buffer size
              -\b-c\bc     The maximum size of core files created
              -\b-d\bd     The maximum size of a process's data segment
              -\b-e\be     The maximum scheduling priority ("nice")
              -\b-f\bf     The  maximum  size  of files written by the shell and its
                     children
              -\b-i\bi     The maximum number of pending signals
              -\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-q\bq     The maximum number of bytes in POSIX message queues
              -\b-r\br     The maximum real-time scheduling priority
              -\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
              -\b-x\bx     The maximum number of file locks
              -\b-T\bT     The maximum number of threads

              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-T\bT,  -\b-b\bb, -\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 specified, each _\bn_\ba_\bm_\be refers to a shell func-
              tion, and the function definition is removed.  Each unset  vari-
              able  or function is removed from the environment passed to sub-
              sequent commands.  If any of 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
              properties, even if they are subsequently reset.  The exit  sta-
              tus is true unless a _\bn_\ba_\bm_\be is readonly.

       w\bwa\bai\bit\bt [_\bn _\b._\b._\b.]
              Wait  for each specified process and return its termination sta-
              tus.  Each _\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  pro-
              cesses  are  waited  for,  and  the return status is zero.  If _\bn
              specifies a non-existent process or job, the  return  status  is
              127.   Otherwise,  the  return  status is the exit status of the
              last process or job waited for.

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 >> redirect-
              ion 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
       process is stopped, the shell immediately executes the next command  in
       the  sequence.   It  suffices to place the sequence of commands between
       parentheses to force it into a subshell, which  may  be  stopped  as  a
       unit.

       Array variables may not (yet) be exported.

       There may be only one active coprocess at a time.



GNU Bash-4.0                   2008 December 29                        BASH(1)