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BASH(1)			    General Commands Manual		       BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2011 by the Free Software Foundation,	Inc.

DESCRIPTION
       Bash  is	 an  sh-compatible  command language interpreter that executes
       commands	read from the standard input or	from a file.  Bash also	incor-
       porates useful features from the	Korn and C shells (ksh and csh).

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

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

       -c string If the	-c option is present,  then  commands  are  read  from
		 string.   If  there  are arguments after the string, they are
		 assigned to the positional parameters,	starting with $0.
       -i	 If the	-i option is present, the shell	is interactive.
       -l	 Make bash act as if it	had been invoked as a login shell (see
		 INVOCATION below).
       -r	 If  the  -r  option  is present, the shell becomes restricted
		 (see RESTRICTED SHELL below).
       -s	 If the	-s 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.
       -D	 A  list of all	double-quoted strings preceded by $ is printed
		 on the	standard output.  These	are the	strings	that are  sub-
		 ject to language translation when the current locale is not C
		 or POSIX.  This implies the -n	option;	no  commands  will  be
		 executed.
       [-+]O [shopt_option]
		 shopt_option  is  one	of  the	 shell options accepted	by the
		 shopt	builtin	 (see  SHELL  BUILTIN  COMMANDS	 below).    If
		 shopt_option is present, -O sets the value of that option; +O
		 unsets	it.  If	shopt_option is	not supplied,  the  names  and
		 values	 of the	shell options accepted by shopt	are printed on
		 the standard output.  If the invocation  option  is  +O,  the
		 output	is displayed in	a format that may be reused as input.
       --	 A  --	signals	the end	of options and disables	further	option
		 processing.  Any arguments after the -- are treated as	 file-
		 names and arguments.  An argument of -	is equivalent to --.

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

       --debugger
	      Arrange for the debugger profile to be executed before the shell
	      starts.  Turns on	extended debugging mode	(see  the  description
	      of the extdebug option to	the shopt builtin below).
       --dump-po-strings
	      Equivalent  to -D, but the output	is in the GNU gettext po (por-
	      table object) file format.
       --dump-strings
	      Equivalent to -D.
       --help Display a	usage message on standard  output  and	exit  success-
	      fully.
       --init-file file
       --rcfile	file
	      Execute commands from file instead of the	standard personal ini-
	      tialization file ~/.bashrc if the	shell is interactive (see  IN-
	      VOCATION below).

       --login
	      Equivalent to -l.

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

       --noprofile
	      Do not read either the system-wide startup file /etc/profile  or
	      any   of	the  personal  initialization  files  ~/.bash_profile,
	      ~/.bash_login, or	~/.profile.   By  default,  bash  reads	 these
	      files  when  it  is invoked as a login shell (see	INVOCATION be-
	      low).

       --norc Do  not  read  and  execute  the	personal  initialization  file
	      ~/.bashrc	if the shell is	interactive.  This option is on	by de-
	      fault if the shell is invoked as sh.

       --posix
	      Change the behavior of bash where	the default operation  differs
	      from the POSIX standard to match the standard (posix mode).

       --restricted
	      The shell	becomes	restricted (see	RESTRICTED SHELL below).

       --rpm-requires
	      Produce the list of files	that are required for the shell	script
	      to run.  This implies '-n' and is	subject	to  the	 same  limita-
	      tions as compile time error checking checking; Command substitu-
	      tions, Conditional expressions and eval builtin are  not	parsed
	      so some dependencies may be missed.

       --verbose
	      Equivalent to  -v.

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

ARGUMENTS
       If arguments remain after option	processing, and	neither	the -c nor the
       -s  option  has	been supplied, the first argument is assumed to	be the
       name of a file containing shell commands.  If bash is invoked  in  this
       fashion,	 $0 is set to the name of the file, and	the positional parame-
       ters are	set to the remaining arguments.	 Bash reads and	executes  com-
       mands  from this	file, then exits.  Bash's exit status is the exit sta-
       tus of the last command executed	in the script.	If no commands are ex-
       ecuted,	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 PATH	for the	script.

INVOCATION
       A  login	shell is one whose first character of argument zero is a -, or
       one started with	the --login option.

       An interactive shell is one started without  non-option	arguments  and
       without the -c option whose standard input and error are	both connected
       to terminals (as	determined by isatty(3)), or one started with  the  -i
       option.	 PS1 is	set and	$- includes i if bash is interactive, allowing
       a shell script or a startup file	to test	this state.

       The following paragraphs	describe how bash executes its startup	files.
       If  any	of  the	files exist but	cannot be read,	bash reports an	error.
       Tildes are expanded in file names as described below under Tilde	Expan-
       sion in the EXPANSION section.

       When  bash is invoked as	an interactive login shell, or as a non-inter-
       active shell with the --login option, it	first reads and	executes  com-
       mands  from  the	file /etc/profile, if that file	exists.	 After reading
       that file, it looks for ~/.bash_profile,	~/.bash_login, and ~/.profile,
       in  that	order, and reads and executes commands from the	first one that
       exists and is readable.	The --noprofile	option may be  used  when  the
       shell is	started	to inhibit this	behavior.

       When  a	login  shell  exits, bash reads	and executes commands from the
       files ~/.bash_logout and	/etc/bash.bash_logout, if the files exists.

       When an interactive shell that is not a login shell  is	started,  bash
       reads  and executes commands from ~/.bashrc, if that file exists.  This
       may be inhibited	by using the --norc option.  The --rcfile file	option
       will  force  bash  to  read  and	 execute commands from file instead of
       ~/.bashrc.

       When bash is started non-interactively, to run a	shell script, for  ex-
       ample,  it  looks for the variable BASH_ENV 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.	 Bash behaves as if the	following com-
       mand were executed:
	      if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
       but the value of	the PATH variable is not used to search	for  the  file
       name.

       If  bash	is invoked with	the name sh, it	tries to mimic the startup be-
       havior of historical versions of	sh as closely as possible, while  con-
       forming	to the POSIX standard as well.	When invoked as	an interactive
       login shell, or a non-interactive shell with  the  --login  option,  it
       first  attempts	to  read  and  execute	commands from /etc/profile and
       ~/.profile, in that order.  The --noprofile option may be used  to  in-
       hibit  this  behavior.	When  invoked as an interactive	shell with the
       name sh,	bash looks for the variable ENV, 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 sh does not attempt to read and exe-
       cute  commands from any other startup files, the	--rcfile option	has no
       effect.	A non-interactive shell	invoked	with the name sh does not  at-
       tempt to	read any other startup files.  When invoked as sh, bash	enters
       posix mode after	the startup files are read.

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

       Bash attempts to	determine when it is being run with its	standard input
       connected to a network connection, as when executed by the remote shell
       daemon, usually rshd, or	the secure shell daemon	sshd.  If bash	deter-
       mines  it  is being run in this fashion,	it reads and executes commands
       from ~/.bashrc, if that file exists and is readable.  It	 will  not  do
       this  if	 invoked as sh.	 The --norc option may be used to inhibit this
       behavior, and the --rcfile option may be	used to	force another file  to
       be  read,  but  rshd does not generally invoke the shell	with those op-
       tions 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 -p option is not supplied, no startup
       files are read, shell functions are not inherited from the environment,
       the  SHELLOPTS, BASHOPTS, CDPATH, and GLOBIGNORE	variables, if they ap-
       pear in the environment,	are ignored, and the effective user id is  set
       to  the	real user id.  If the -p option	is supplied at invocation, the
       startup behavior	is the same, but the effective user id is not reset.

DEFINITIONS
       The following definitions are used throughout the rest  of  this	 docu-
       ment.
       blank  A	space or tab.
       word   A	 sequence  of  characters  considered  as a single unit	by the
	      shell.  Also known as a token.
       name   A	word consisting	only of	 alphanumeric  characters  and	under-
	      scores,  and beginning with an alphabetic	character or an	under-
	      score.  Also referred to as an identifier.
       metacharacter
	      A	character that,	when unquoted, separates words.	  One  of  the
	      following:
	      |	 & ; ( ) < > space tab
       control operator
	      A	token that performs a control function.	 It is one of the fol-
	      lowing symbols:
	      || & && ;	;; ( ) | |& <newline>

RESERVED WORDS
       Reserved	words 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 SHELL GRAMMAR below)	or  the	 third
       word of a case or for command:

       !  case	do done	elif else esac fi for function if in select then until
       while { } time [[ ]]

SHELL GRAMMAR
   Simple Commands
       A simple	command	is a sequence of optional  variable  assignments  fol-
       lowed  by  blank-separated  words and redirections, and terminated by a
       control operator.  The first word specifies the command to be executed,
       and  is passed as argument zero.	 The remaining words are passed	as ar-
       guments to the invoked command.

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

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

	      [time [-p]] [ ! ]	command	[ [|||&] command2 ... ]

       The standard output of command is connected via a pipe to the  standard
       input  of  command2.   This connection is performed before any redirec-
       tions specified by the command (see REDIRECTION below).	If |& is used,
       the standard error of command is	connected to command2's	standard input
       through the pipe; it is shorthand for 2>&1 |.  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  pipefail  option  is enabled.  If pipefail is enabled, the
       pipeline's return status	is the value of	the last  (rightmost)  command
       to  exit	 with a	non-zero status, or zero if all	commands exit success-
       fully.  If the reserved word !  precedes	a pipeline, the	exit status of
       that  pipeline  is the logical negation of the exit status as described
       above.  The shell waits for all commands	in the pipeline	 to  terminate
       before returning	a value.

       If  the	time 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 -p option changes the output	format to that
       specified by POSIX.  When the shell is in posix mode, it	does not  rec-
       ognize  time  as	 a  reserved word if the next token begins with	a `-'.
       The TIMEFORMAT variable may be set to a format  string  that  specifies
       how  the	timing information should be displayed;	see the	description of
       TIMEFORMAT under	Shell Variables	below.

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

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

   Lists
       A list is a sequence of one or more pipelines separated by one  of  the
       operators ;, &, &&, or ||, and optionally terminated by one of ;, &, or
       <newline>.

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

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

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

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

	      command1 && command2

       command2	 is  executed if, and only if, command1	returns	an exit	status
       of zero.

       An OR list has the form

	      command1 || command2

       command2	is executed if and only	if command1 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.

   Compound Commands
       A compound command is one of the	following:

       (list) list is executed in a subshell environment (see  COMMAND	EXECU-
	      TION  ENVIRONMENT	below).	 Variable assignments and builtin com-
	      mands that affect	the shell's environment	do not remain  in  ef-
	      fect after the command completes.	 The return status is the exit
	      status of	list.

       { list; }
	      list is simply executed in the current shell environment.	  list
	      must  be	terminated with	a newline or semicolon.	 This is known
	      as a group command.  The return status is	 the  exit  status  of
	      list.   Note that	unlike the metacharacters ( and	), { and } are
	      reserved words 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  list  by	whitespace  or	another	 shell
	      metacharacter.

       ((expression))
	      The expression is	evaluated according to the rules described be-
	      low under	ARITHMETIC EVALUATION.	If the value of	the expression
	      is non-zero, the return status is	0; otherwise the return	status
	      is 1.  This is exactly equivalent	to let "expression".

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

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

	      When  the	 == and	!= operators are used, the string to the right
	      of the operator is considered a pattern and matched according to
	      the  rules described below under Pattern Matching.  If the shell
	      option nocasematch is enabled, the match	is  performed  without
	      regard  to  the case of alphabetic characters.  The return value
	      is 0 if the string matches (==) or does not match	(!=) the  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, =~, is available, with  the  same
	      precedence  as  ==  and  !=.  When it is used, the string	to the
	      right of the operator is considered an extended regular  expres-
	      sion and matched accordingly (as in regex(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 nocasematch
	      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  BASH_REMATCH.   The  element of
	      BASH_REMATCH with	index 0	is the portion of the string  matching
	      the entire regular expression.  The element of BASH_REMATCH with
	      index n is the portion of	the string matching the	nth  parenthe-
	      sized subexpression.

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

	      (	expression )
		     Returns the value of expression.  This  may  be  used  to
		     override the normal precedence of operators.
	      !	expression
		     True if expression	is false.
	      expression1 && expression2
		     True if both expression1 and expression2 are true.
	      expression1 || expression2
		     True if either expression1	or expression2 is true.

	      The && and || operators do not evaluate expression2 if the value
	      of expression1 is	sufficient to determine	the  return  value  of
	      the entire conditional expression.

       for name	[ [ in [ word ... ] ] ;	] do list ; done
	      The list of words	following in is	expanded, generating a list of
	      items.  The variable name	is set to each element of this list in
	      turn,  and  list is executed each	time.  If the in word is omit-
	      ted, the for command executes list once for each positional  pa-
	      rameter  that  is	set (see PARAMETERS below).  The return	status
	      is the exit status of the	last command that  executes.   If  the
	      expansion	of the items following in results in an	empty list, no
	      commands are executed, and the return status is 0.

       for (( expr1 ; expr2 ; expr3 )) ; do list ; done
	      First, the arithmetic expression expr1 is	evaluated according to
	      the  rules  described  below  under  ARITHMETIC EVALUATION.  The
	      arithmetic expression expr2 is then evaluated  repeatedly	 until
	      it  evaluates  to	zero.  Each time expr2 evaluates to a non-zero
	      value, list is executed and the arithmetic expression  expr3  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 list that is executed,	or false if any	of the expres-
	      sions is invalid.

       select name [ in	word ] ; do list ; done
	      The list of words	following in is	expanded, generating a list of
	      items.  The set of expanded words	is printed on the standard er-
	      ror, each	preceded by a number.  If the in word is omitted,  the
	      positional  parameters  are printed (see PARAMETERS below).  The
	      PS3 prompt is then displayed and a line read from	 the  standard
	      input.  If the line consists of a	number corresponding to	one of
	      the displayed words, then	the value of name is set to that word.
	      If  the line is empty, the words and prompt are displayed	again.
	      If EOF is	read, the command completes.   Any  other  value  read
	      causes  name  to	be set to null.	 The line read is saved	in the
	      variable REPLY.  The list	is executed after each selection until
	      a	 break	command	is executed.  The exit status of select	is the
	      exit status of the last command executed in list,	or zero	if  no
	      commands were executed.

       case word in [ [(] pattern [ | pattern ]	... ) list ;; ]	... esac
	      A	case command first expands word, and tries to match it against
	      each pattern in turn, using the same matching rules as for path-
	      name  expansion (see Pathname Expansion below).  The word	is ex-
	      panded using tilde expansion, parameter and variable  expansion,
	      arithmetic substitution, command substitution, process substitu-
	      tion and quote removal.  Each pattern examined is	expanded using
	      tilde  expansion,	 parameter  and	variable expansion, arithmetic
	      substitution, command substitution,  and	process	 substitution.
	      If  the  shell  option nocasematch is enabled, the match is per-
	      formed without regard to	the  case  of  alphabetic  characters.
	      When  a  match is	found, the corresponding list is executed.  If
	      the ;; operator is used, no subsequent matches are attempted af-
	      ter the first pattern match.  Using ;& in	place of ;; causes ex-
	      ecution to continue with the list	associated with	the  next  set
	      of  patterns.  Using ;;& in place	of ;; causes the shell to test
	      the next pattern list in the statement, if any, and execute  any
	      associated  list 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 list.

       if list;	then list; [ elif list;	then list; ] ... [ else	list; ]	fi
	      The  if  list is executed.  If its exit status is	zero, the then
	      list is executed.	 Otherwise, each  elif	list  is  executed  in
	      turn,  and  if  its  exit	status is zero,	the corresponding then
	      list is executed and the command completes.  Otherwise, the else
	      list  is executed, if present.  The exit status is the exit sta-
	      tus of the last command executed,	or zero	if no condition	tested
	      true.

       while list-1; do	list-2;	done
       until list-1; do	list-2;	done
	      The  while command continuously executes the list	list-2 as long
	      as the last command in the list list-1 returns an	exit status of
	      zero.   The until	command	is identical to	the while command, ex-
	      cept that	the test is negated; list-2 is executed	as long	as the
	      last command in list-1 returns a non-zero	exit status.  The exit
	      status of	the while and until commands is	the exit status	of the
	      last command executed in list-2, or zero if none was executed.

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

       The format for a	coprocess is:

	      coproc [NAME] command [redirections]

       This creates a coprocess	named NAME.  If	NAME is	not supplied, the  de-
       fault name is COPROC.  NAME must	not be supplied	if command is a	simple
       command (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 Arrays below) named NAME in the context of the exe-
       cuting  shell.	The standard output of command is connected via	a pipe
       to a file descriptor in the executing shell, and	that  file  descriptor
       is assigned to NAME[0].	The standard input of command is connected via
       a pipe to a file	descriptor in the executing shell, and that  file  de-
       scriptor	 is  assigned to NAME[1].  This	pipe is	established before any
       redirections specified by the command  (see  REDIRECTION	 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	NAME_PID.  The wait builtin command may	be used	 to  wait  for
       the coprocess to	terminate.

       The return status of a coprocess	is the exit status of command.

   Shell Function Definitions
       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:

       name () compound-command	[redirection]
       function	name [()] compound-command [redirection]
	      This  defines a function named name.  The	reserved word function
	      is optional.  If the function reserved  word  is	supplied,  the
	      parentheses  are optional.  The body of the function is the com-
	      pound command compound-command (see  Compound  Commands  above).
	      That  command is usually a list of commands between { and	}, but
	      may be any command listed	under Compound Commands	 above.	  com-
	      pound-command is executed	whenever name is specified as the name
	      of a simple command.  Any	redirections (see  REDIRECTION	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 FUNCTIONS	below.)

COMMENTS
       In a non-interactive shell, or an interactive shell in which the	inter-
       active_comments	option	to  the	 shopt	builtin	 is enabled (see SHELL
       BUILTIN COMMANDS	below),	a word beginning with #	causes that  word  and
       all  remaining  characters  on that line	to be ignored.	An interactive
       shell without the interactive_comments option enabled  does  not	 allow
       comments.  The interactive_comments option is on	by default in interac-
       tive shells.

QUOTING
       Quoting 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 metacharacters listed above under DEFINITIONS 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  HIS-
       TORY EXPANSION below), the history expansion character, usually !, must
       be quoted to prevent history expansion.

       There are  three	 quoting  mechanisms:  the  escape  character,	single
       quotes, and double quotes.

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

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

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

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

       Words of	the form $'string' are treated specially.  The word expands to
       string,	with backslash-escaped characters replaced as specified	by the
       ANSI C standard.	 Backslash escape sequences, if	present,  are  decoded
       as follows:
	      \a     alert (bell)
	      \b     backspace
	      \e
	      \E     an	escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal	tab
	      \v     vertical tab
	      \\     backslash
	      \'     single quote
	      \"     double quote
	      \nnn   the  eight-bit  character	whose value is the octal value
		     nnn (one to three digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (one or two hex digits)
	      \uHHHH the  Unicode (ISO/IEC 10646) character whose value	is the
		     hexadecimal value HHHH (one to four hex digits)
	      \UHHHHHHHH
		     the Unicode (ISO/IEC 10646) character whose value is  the
		     hexadecimal value HHHHHHHH	(one to	eight hex digits)
	      \cx    a control-x character

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

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

PARAMETERS
       A  parameter is an entity that stores values.  It can be	a name,	a num-
       ber, or one of the special characters listed below under	Special	Param-
       eters.	A variable is a	parameter denoted by a name.  A	variable has a
       value and zero or more attributes.  Attributes are assigned  using  the
       declare builtin command (see declare below in SHELL BUILTIN COMMANDS).

       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 unset builtin command (see SHELL BUILTIN COMMANDS below).

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

	      name=[value]

       If  value  is not given,	the variable is	assigned the null string.  All
       values undergo tilde expansion, parameter and variable expansion,  com-
       mand  substitution, arithmetic expansion, and quote removal (see	EXPAN-
       SION below).  If	the variable has its integer attribute set, then value
       is evaluated as an arithmetic expression	even if	the $((...)) expansion
       is not used (see	Arithmetic Expansion below).  Word  splitting  is  not
       performed,  with	the exception of "$@" as explained below under Special
       Parameters.  Pathname expansion is not  performed.   Assignment	state-
       ments  may also appear as arguments to the alias, declare, typeset, ex-
       port, readonly, and local 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, value 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	Arrays below), the variable's value is not un-
       set  (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, value	is  expanded  and  ap-
       pended to the variable's	value.

   Positional Parameters
       A  positional  parameter	 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 set 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 FUNCTIONS below).

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

   Special Parameters
       The  shell  treats  several parameters specially.  These	parameters may
       only be referenced; assignment to them is not allowed.
       *      Expands to the positional	parameters, starting from  one.	  When
	      the  expansion occurs within double quotes, it expands to	a sin-
	      gle word with the	value of each parameter	separated by the first
	      character	of the IFS special variable.  That is, "$*" is equiva-
	      lent to "$1c$2c...", where c is the first	character of the value
	      of  the IFS variable.  If	IFS is unset, the parameters are sepa-
	      rated by spaces.	If IFS is  null,  the  parameters  are	joined
	      without intervening separators.
       @      Expands  to  the positional parameters, starting from one.  When
	      the expansion occurs within double quotes,  each	parameter  ex-
	      pands  to	 a separate word.  That	is, "$@" is equivalent to "$1"
	      "$2" ...	If the double-quoted expansion occurs within  a	 word,
	      the  expansion  of the first parameter is	joined with the	begin-
	      ning part	of the original	word, and the expansion	 of  the  last
	      parameter	 is  joined  with  the last part of the	original word.
	      When there are no	positional parameters, "$@" and	$@  expand  to
	      nothing (i.e., they are removed).
       #      Expands to the number of positional parameters in	decimal.
       ?      Expands  to  the exit status of the most recently	executed fore-
	      ground pipeline.
       -      Expands to the current option flags as  specified	 upon  invoca-
	      tion,  by	the set	builtin	command, or those set by the shell it-
	      self (such as the	-i option).
       $      Expands to the process ID	of the shell.  In a  ()	 subshell,  it
	      expands  to  the	process	 ID of the current shell, not the sub-
	      shell.
       !      Expands to the process ID	of the most  recently  executed	 back-
	      ground (asynchronous) command.
       0      Expands  to  the name of the shell or shell script.  This	is set
	      at shell initialization.	If bash	is invoked with	a file of com-
	      mands,  $0  is set to the	name of	that file.  If bash is started
	      with the -c option, then $0 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 bash,	as given  by  argument
	      zero.
       _      At  shell	 startup,  set to the absolute pathname	used to	invoke
	      the shell	or shell script	being executed as passed in the	 envi-
	      ronment or argument list.	 Subsequently, expands to the last ar-
	      gument 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.

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands to the full file name used to invoke  this  instance  of
	      bash.
       BASHOPTS
	      A	 colon-separated  list of enabled shell	options.  Each word in
	      the list is a valid argument for the  -s	option	to  the	 shopt
	      builtin command (see SHELL BUILTIN COMMANDS below).  The options
	      appearing	in BASHOPTS are	those reported as  on  by  shopt.   If
	      this  variable  is  in the environment when bash starts up, each
	      shell option in the list will  be	 enabled  before  reading  any
	      startup files.  This variable is read-only.
       BASHPID
	      Expands  to  the	process	 ID of the current bash	process.  This
	      differs from $$ under certain circumstances, such	 as  subshells
	      that do not require bash to be re-initialized.
       BASH_ALIASES
	      An  associative  array  variable whose members correspond	to the
	      internal list of aliases as maintained  by  the  alias  builtin.
	      Elements added to	this array appear in the alias list; unsetting
	      array elements cause aliases to be removed from the alias	list.
       BASH_ARGC
	      An array variable	whose values are the number of	parameters  in
	      each frame of the	current	bash execution call stack.  The	number
	      of parameters to	the  current  subroutine  (shell  function  or
	      script  executed	with  .	or source) is at the top of the	stack.
	      When a subroutine	is executed, the number	of  parameters	passed
	      is pushed	onto BASH_ARGC.	 The shell sets	BASH_ARGC only when in
	      extended debugging mode (see the description of the extdebug op-
	      tion to the shopt	builtin	below)
       BASH_ARGV
	      An  array	 variable containing all of the	parameters in the cur-
	      rent bash	execution call stack.  The final parameter of the last
	      subroutine  call is at the top of	the stack; the first parameter
	      of the initial call is at	the bottom.  When a subroutine is exe-
	      cuted,  the  parameters supplied are pushed onto BASH_ARGV.  The
	      shell sets BASH_ARGV only	when in	extended debugging  mode  (see
	      the  description of the extdebug option to the shopt builtin be-
	      low)
       BASH_CMDS
	      An associative array variable whose members  correspond  to  the
	      internal	hash  table  of	 commands  as  maintained  by the hash
	      builtin.	Elements added to this array appear in the hash	table;
	      unsetting	 array	elements cause commands	to be removed from the
	      hash table.
       BASH_COMMAND
	      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.
       BASH_EXECUTION_STRING
	      The command argument to the -c invocation	option.
       BASH_LINENO
	      An  array	 variable whose	members	are the	line numbers in	source
	      files where each corresponding member of FUNCNAME	 was  invoked.
	      ${BASH_LINENO[$i]}  is  the  line	 number	 in  the  source  file
	      (${BASH_SOURCE[$i+1]})  where  ${FUNCNAME[$i]}  was  called  (or
	      ${BASH_LINENO[$i-1]}  if	referenced  within another shell func-
	      tion).  Use LINENO to obtain the current line number.
       BASH_REMATCH
	      An array variable	whose members are assigned by  the  =~	binary
	      operator	to the [[ conditional command.	The element with index
	      0	is the portion of the string matching the entire  regular  ex-
	      pression.	 The element with index	n is the portion of the	string
	      matching the nth parenthesized subexpression.  This variable  is
	      read-only.
       BASH_SOURCE
	      An  array	 variable whose	members	are the	source filenames where
	      the corresponding	shell function names  in  the  FUNCNAME	 array
	      variable are defined.  The shell function	${FUNCNAME[$i]}	is de-
	      fined  in	 the   file   ${BASH_SOURCE[$i]}   and	 called	  from
	      ${BASH_SOURCE[$i+1]}.
       BASH_SUBSHELL
	      Incremented  by one each time a subshell or subshell environment
	      is spawned.  The initial value is	0.
       BASH_VERSINFO
	      A	readonly array variable	whose members hold version information
	      for  this	 instance  of  bash.  The values assigned to the array
	      members are as follows:
	      BASH_VERSINFO[0]	      The major	version	number (the release).
	      BASH_VERSINFO[1]	      The minor	version	number (the version).
	      BASH_VERSINFO[2]	      The patch	level.
	      BASH_VERSINFO[3]	      The build	version.
	      BASH_VERSINFO[4]	      The release status (e.g.,	beta1).
	      BASH_VERSINFO[5]	      The value	of MACHTYPE.
       BASH_VERSION
	      Expands to a string describing the version of this  instance  of
	      bash.
       COMP_CWORD
	      An  index	 into ${COMP_WORDS} of the word	containing the current
	      cursor position.	This variable is available only	in shell func-
	      tions  invoked  by  the  programmable completion facilities (see
	      Programmable Completion below).
       COMP_KEY
	      The key (or final	key of a key sequence) used to invoke the cur-
	      rent completion function.
       COMP_LINE
	      The  current  command  line.  This variable is available only in
	      shell functions and external commands invoked  by	 the  program-
	      mable completion facilities (see Programmable Completion below).
       COMP_POINT
	      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 ${#COMP_LINE}.  This  variable  is  available  only  in
	      shell  functions	and  external commands invoked by the program-
	      mable completion facilities (see Programmable Completion below).
       COMP_TYPE
	      Set to an	integer	value corresponding to the type	of  completion
	      attempted	 that  caused a	completion function to be called: TAB,
	      for normal completion, ?,	for listing completions	after  succes-
	      sive  tabs,  !, for listing alternatives on partial word comple-
	      tion, @, to list completions if the word is not  unmodified,  or
	      %,  for  menu  completion.   This	 variable is available only in
	      shell functions and external commands invoked  by	 the  program-
	      mable completion facilities (see Programmable Completion below).
       COMP_WORDBREAKS
	      The  set	of characters that the readline	library	treats as word
	      separators when performing word completion.  If  COMP_WORDBREAKS
	      is  unset, it loses its special properties, even if it is	subse-
	      quently reset.
       COMP_WORDS
	      An array variable	(see Arrays below) consisting of the  individ-
	      ual  words  in the current command line.	The line is split into
	      words as readline	would split it,	using COMP_WORDBREAKS  as  de-
	      scribed  above.	This variable is available only	in shell func-
	      tions invoked by the  programmable  completion  facilities  (see
	      Programmable Completion below).
       COPROC An  array	 variable  (see	Arrays below) created to hold the file
	      descriptors for output from and input to	an  unnamed  coprocess
	      (see Coprocesses above).
       DIRSTACK
	      An array variable	(see Arrays below) containing the current con-
	      tents of the directory stack.  Directories appear	in  the	 stack
	      in  the order they are displayed by the dirs builtin.  Assigning
	      to members of this array variable	may be used to modify directo-
	      ries  already in the stack, but the pushd	and popd builtins must
	      be used to add and remove	directories.  Assignment to this vari-
	      able  will not change the	current	directory.  If DIRSTACK	is un-
	      set, it loses its	special	properties, even if it is subsequently
	      reset.
       EUID   Expands  to  the effective user ID of the	current	user, initial-
	      ized at shell startup.  This variable is readonly.
       FUNCNAME
	      An array variable	containing the names of	 all  shell  functions
	      currently	in the execution call stack.  The element with index 0
	      is the name of any currently-executing shell function.  The bot-
	      tom-most	element	 (the  one  with the highest index) is "main".
	      This variable exists only	when a shell  function	is  executing.
	      Assignments  to FUNCNAME have no effect and return an error sta-
	      tus.  If FUNCNAME	is unset, it  loses  its  special  properties,
	      even if it is subsequently reset.

	      This  variable  can  be  used  with BASH_LINENO and BASH_SOURCE.
	      Each  element  of	 FUNCNAME  has	 corresponding	 elements   in
	      BASH_LINENO and BASH_SOURCE to describe the call stack.  For in-
	      stance,	${FUNCNAME[$i]}	  was	 called	   from	   the	  file
	      ${BASH_SOURCE[$i+1]}  at	line  number  ${BASH_LINENO[$i]}.  The
	      caller builtin displays the current call stack using this	infor-
	      mation.
       GROUPS An  array	 variable  containing  the list	of groups of which the
	      current user is a	member.	 Assignments to	GROUPS have no	effect
	      and  return  an  error status.  If GROUPS	is unset, it loses its
	      special properties, even if it is	subsequently reset.
       HISTCMD
	      The history number, or index in the history list,	of the current
	      command.	 If HISTCMD is unset, it loses its special properties,
	      even if it is subsequently reset.
       HOSTNAME
	      Automatically set	to the name of the current host.
       HOSTTYPE
	      Automatically set	to a string that uniquely describes  the  type
	      of  machine  on which bash is executing.	The default is system-
	      dependent.
       LINENO 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 LINENO	is unset, it loses its special proper-
	      ties, even if it is subsequently reset.
       MACHTYPE
	      Automatically  set  to  a	string that fully describes the	system
	      type on which bash is executing, in the  standard	 GNU  cpu-com-
	      pany-system format.  The default is system-dependent.
       MAPFILE
	      An  array	 variable  (see	Arrays below) created to hold the text
	      read by the mapfile builtin when no variable name	is supplied.
       OLDPWD The previous working directory as	set by the cd command.
       OPTARG The value	of the last option argument processed by  the  getopts
	      builtin command (see SHELL BUILTIN COMMANDS below).
       OPTIND The  index  of  the next argument	to be processed	by the getopts
	      builtin command (see SHELL BUILTIN COMMANDS below).
       OSTYPE Automatically set	to a string that describes the operating  sys-
	      tem  on  which  bash is executing.  The default is system-depen-
	      dent.
       PIPESTATUS
	      An array variable	(see Arrays 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).
       PPID   The process ID of	the shell's parent.  This  variable  is	 read-
	      only.
       PWD    The current working directory as set by the cd command.
       RANDOM 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 RANDOM.  If RANDOM is	unset,
	      it loses its special properties, even if it is subsequently  re-
	      set.
       READLINE_LINE
	      The contents of the readline line	buffer,	for use	with "bind -x"
	      (see SHELL BUILTIN COMMANDS below).
       READLINE_POINT
	      The position of the insertion point in the readline line buffer,
	      for use with "bind -x" (see SHELL	BUILTIN	COMMANDS below).
       REPLY  Set  to  the line	of input read by the read builtin command when
	      no arguments are supplied.
       SECONDS
	      Each time	this parameter is referenced, the  number  of  seconds
	      since  shell  invocation is returned.  If	a value	is assigned to
	      SECONDS, the value returned upon subsequent  references  is  the
	      number  of seconds since the assignment plus the value assigned.
	      If SECONDS is unset, it loses its	special	properties, even if it
	      is subsequently reset.
       SHELLOPTS
	      A	 colon-separated  list of enabled shell	options.  Each word in
	      the list is a valid argument  for	 the  -o  option  to  the  set
	      builtin command (see SHELL BUILTIN COMMANDS below).  The options
	      appearing	in SHELLOPTS are those reported	as on by set  -o.   If
	      this  variable  is  in the environment when bash starts up, each
	      shell option in the list will  be	 enabled  before  reading  any
	      startup files.  This variable is read-only.
       SHLVL  Incremented by one each time an instance of bash is started.
       UID    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, bash as-
       signs a default value to	a variable; these cases	are noted below.

       BASH_ENV
	      If  this parameter is set	when bash is executing a shell script,
	      its value	is interpreted as a filename  containing  commands  to
	      initialize the shell, as in ~/.bashrc.  The value	of BASH_ENV is
	      subjected	to  parameter  expansion,  command  substitution,  and
	      arithmetic  expansion  before  being interpreted as a file name.
	      PATH is not used to search for the resultant file	name.
       BASH_XTRACEFD
	      If set to	an integer corresponding to a valid  file  descriptor,
	      bash  will  write	 the trace output generated when set -x	is en-
	      abled to that file descriptor.  The file	descriptor  is	closed
	      when  BASH_XTRACEFD is unset or assigned a new value.  Unsetting
	      BASH_XTRACEFD or assigning it the	empty string causes the	 trace
	      output  to  be  sent  to	the standard error.  Note that setting
	      BASH_XTRACEFD to 2 (the standard error file descriptor) and then
	      unsetting	it will	result in the standard error being closed.
       CDPATH The  search  path	for the	cd command.  This is a colon-separated
	      list of directories in which the shell looks for destination di-
	      rectories	 specified  by	the  cd	 command.   A  sample value is
	      ".:~:/usr".
       COLUMNS
	      Used by the select compound command to  determine	 the  terminal
	      width when printing selection lists.  Automatically set upon re-
	      ceipt of a SIGWINCH.
       COMPREPLY
	      An array variable	from which bash	reads the possible completions
	      generated	 by  a shell function invoked by the programmable com-
	      pletion facility (see Programmable Completion below).
       EMACS  If bash 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.
       ENV    Similar to BASH_ENV; used	when the shell	is  invoked  in	 POSIX
	      mode.
       FCEDIT The default editor for the fc builtin command.
       FIGNORE
	      A	 colon-separated  list	of  suffixes to	ignore when performing
	      filename completion (see READLINE	below).	 A filename whose suf-
	      fix  matches  one	of the entries in FIGNORE is excluded from the
	      list of matched filenames.  A sample value is ".o:~".
       FUNCNEST
	      If set to	a numeric value	greater	 than  0,  defines  a  maximum
	      function	nesting	 level.	 Function invocations that exceed this
	      nesting level will cause the current command to abort.
       GLOBIGNORE
	      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
	      GLOBIGNORE, it is	removed	from the list of matches.
       HISTCONTROL
	      A	 colon-separated  list	of values controlling how commands are
	      saved on the history list.  If the list of values	 includes  ig-
	      norespace,  lines	 which	begin  with  a space character are not
	      saved in the history list.  A value of ignoredups	 causes	 lines
	      matching the previous history entry to not be saved.  A value of
	      ignoreboth is shorthand for ignorespace and ignoredups.  A value
	      of erasedups 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	HISTCONTROL 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 HISTIGNORE.  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 HISTCONTROL.
       HISTFILE
	      The name of the file in which command history is saved (see HIS-
	      TORY  below).   The default value	is ~/.bash_history.  If	unset,
	      the command history is not saved when an interactive  shell  ex-
	      its.
       HISTFILESIZE
	      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.
       HISTIGNORE
	      A	colon-separated	list of	patterns used to decide	which  command
	      lines  should be saved on	the history list.  Each	pattern	is an-
	      chored at	the beginning of the line and must match the  complete
	      line  (no	 implicit  `*'	is  appended).	Each pattern is	tested
	      against the line after the checks	specified by  HISTCONTROL  are
	      applied.	In addition to the normal shell	pattern	matching char-
	      acters, `&' matches the previous history line.  `&' may  be  es-
	      caped  using  a  backslash;  the backslash is removed before at-
	      tempting a match.	 The second and	subsequent lines of  a	multi-
	      line  compound command are not tested, and are added to the his-
	      tory regardless of the value of HISTIGNORE.
       HISTSIZE
	      The number of commands to	remember in the	command	 history  (see
	      HISTORY below).  The default value is 500.
       HISTTIMEFORMAT
	      If  this	variable  is  set and not null,	its value is used as a
	      format string for	strftime(3) to print the time stamp associated
	      with  each  history  entry displayed by the history 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.
       HOME   The home directory of the	current	user; the default argument for
	      the cd builtin command.  The value of this variable is also used
	      when performing tilde expansion.
       HOSTFILE
	      Contains	the  name  of  a file in the same format as /etc/hosts
	      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  at-
	      tempted  after  the  value is changed, bash adds the contents of
	      the new file to the existing list.  If HOSTFILE is set, but  has
	      no  value,  or  does  not	name a readable	file, bash attempts to
	      read /etc/hosts to obtain	the list of possible hostname  comple-
	      tions.  When HOSTFILE is unset, the hostname list	is cleared.
       IFS    The Internal Field Separator that	is used	for word splitting af-
	      ter expansion and	to  split  lines  into	words  with  the  read
	      builtin  command.	  The  default	value  is  ``<space><tab><new-
	      line>''.
       IGNOREEOF
	      Controls the action of an	interactive shell on receipt of	an EOF
	      character	as the sole input.  If set, the	value is the number of
	      consecutive EOF characters which must  be	 typed	as  the	 first
	      characters  on an	input line before bash 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, EOF signifies the
	      end of input to the shell.
       INPUTRC
	      The filename for the readline startup file, overriding  the  de-
	      fault of ~/.inputrc (see READLINE	below).
       LANG   Used  to	determine  the	locale	category  for any category not
	      specifically selected with a variable starting with LC_.
       LC_ALL This variable overrides the value	of  LANG  and  any  other  LC_
	      variable specifying a locale category.
       LC_COLLATE
	      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 se-
	      quences within pathname expansion	and pattern matching.
       LC_CTYPE
	      This variable determines the interpretation  of  characters  and
	      the  behavior of character classes within	pathname expansion and
	      pattern matching.
       LC_MESSAGES
	      This variable determines the locale used	to  translate  double-
	      quoted strings preceded by a $.
       LC_NUMERIC
	      This  variable  determines  the  locale category used for	number
	      formatting.
       LINES  Used by the select compound  command  to	determine  the	column
	      length for printing selection lists.  Automatically set upon re-
	      ceipt of a SIGWINCH.
       MAIL   If this parameter	is set to a file or  directory	name  and  the
	      MAILPATH	variable  is not set, bash informs the user of the ar-
	      rival of mail in the specified file or Maildir-format directory.
       MAILCHECK
	      Specifies	how often (in seconds) bash checks for mail.  The  de-
	      fault  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.
       MAILPATH
	      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, $_ expands to
	      the name of the current mailfile.	 Example:
	      MAILPATH='/var/mail/bfox?"You  have  mail":~/shell-mail?"$_  has
	      mail!"'
	      Bash  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/$USER).
       OPTERR If set to	the value 1, bash displays error messages generated by
	      the getopts builtin command (see SHELL BUILTIN COMMANDS  below).
	      OPTERR  is  initialized to 1 each	time the shell is invoked or a
	      shell script is executed.
       PATH   The search path for commands.  It	is a colon-separated  list  of
	      directories  in  which the shell looks for commands (see COMMAND
	      EXECUTION	below).	 A zero-length (null) directory	 name  in  the
	      value of PATH 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 bash.  A common  value  is
	      ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''.
       POSIXLY_CORRECT
	      If  this	variable  is  in the environment when bash starts, the
	      shell enters posix mode before reading the startup files,	as  if
	      the  --posix  invocation option had been supplied.  If it	is set
	      while the	shell is running, bash enables posix mode, as  if  the
	      command set -o posix had been executed.
       PROMPT_COMMAND
	      If set, the value	is executed as a command prior to issuing each
	      primary prompt.
       PROMPT_DIRTRIM
	      If set to	a number greater than zero, the	value is used  as  the
	      number of	trailing directory components to retain	when expanding
	      the \w and \W  prompt  string  escapes  (see  PROMPTING  below).
	      Characters removed are replaced with an ellipsis.
       PS1    The  value  of  this parameter is	expanded (see PROMPTING	below)
	      and used as the primary prompt string.   The  default  value  is
	      ``\s-\v\$	''.
       PS2    The  value of this parameter is expanded as with PS1 and used as
	      the secondary prompt string.  The	default	is ``> ''.
       PS3    The value	of this	parameter is used as the prompt	for the	select
	      command (see SHELL GRAMMAR above).
       PS4    The  value  of  this  parameter  is expanded as with PS1 and the
	      value is printed before each command bash	displays during	an ex-
	      ecution  trace.  The first character of PS4 is replicated	multi-
	      ple times, as necessary, to indicate multiple levels of indirec-
	      tion.  The default is ``+	''.
       SHELL  The full pathname	to the shell is	kept in	this environment vari-
	      able.  If	it is not set when the shell starts, bash  assigns  to
	      it the full pathname of the current user's login shell.
       TIMEFORMAT
	      The  value of this parameter is used as a	format string specify-
	      ing how the timing information for pipelines prefixed  with  the
	      time  reserved word should be displayed.	The % character	intro-
	      duces an escape sequence that is expanded	to  a  time  value  or
	      other  information.  The escape sequences	and their meanings are
	      as follows; the braces denote optional portions.
	      %%	A literal %.
	      %[p][l]R	The elapsed time in seconds.
	      %[p][l]U	The number of CPU seconds spent	in user	mode.
	      %[p][l]S	The number of CPU seconds spent	in system mode.
	      %P	The CPU	percentage, computed as	(%U + %S) / %R.

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

	      The  optional l specifies	a longer format, including minutes, of
	      the form MMmSS.FFs.  The value of	p determines  whether  or  not
	      the fraction is included.

	      If  this	variable  is not set, bash acts	as if it had the value
	      $'\nreal\t%3lR\nuser\t%3lU\nsys%3lS'.  If	the value is null,  no
	      timing  information  is  displayed.  A trailing newline is added
	      when the format string is	displayed.
       TMOUT  If set to	a value	greater	than zero, TMOUT is treated as the de-
	      fault  timeout  for the read builtin.  The select	command	termi-
	      nates if input does not arrive after TMOUT 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 is-
	      suing  the  primary  prompt.   Bash terminates after waiting for
	      that number of seconds if	input does not arrive.
       TMPDIR If set, bash uses	its value as the name of a directory in	 which
	      bash creates temporary files for the shell's use.
       auto_resume
	      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  name	 of  a
	      stopped  job, in this context, is	the command line used to start
	      it.  If set to the value exact, the string supplied  must	 match
	      the  name	 of  a	stopped	 job exactly; if set to	substring, the
	      string supplied needs to match a substring  of  the  name	 of  a
	      stopped  job.  The substring value provides functionality	analo-
	      gous to the %?  job identifier (see JOB CONTROL 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
	      %string job identifier.
       histchars
	      The  two or three	characters which control history expansion and
	      tokenization (see	HISTORY	EXPANSION below).  The first character
	      is  the history expansion	character, the character which signals
	      the start	of a history  expansion,  normally  `!'.   The	second
	      character	 is the	quick substitution character, which is used as
	      shorthand	for re-running the previous command  entered,  substi-
	      tuting  one  string  for another in the command.	The default is
	      `^'.  The	optional third character is the	character which	 indi-
	      cates  that the remainder	of the line is a comment when found as
	      the first	character of a word, normally `#'.  The	 history  com-
	      ment character causes history substitution to be skipped for the
	      remaining	words on the line.  It does not	necessarily cause  the
	      shell parser to treat the	rest of	the line as a comment.

   Arrays
       Bash  provides one-dimensional indexed and associative array variables.
       Any variable may	be used	as an indexed array; the declare 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 name[subscript]=value.  The subscript is treated as
       an  arithmetic expression that must evaluate to a number.  If subscript
       evaluates to a number less than zero, it	is used	as an offset from  one
       greater	than  the array's maximum index	(so a subcript of -1 refers to
       the last	element	of the array).	To explicitly declare an  indexed  ar-
       ray,  use  declare -a name (see SHELL BUILTIN COMMANDS below).  declare
       -a name[subscript] is also accepted; the	subscript is ignored.

       Associative arrays are created using declare -A name.

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

       Arrays	are  assigned  to  using  compound  assignments	 of  the  form
       name=(value1 ...	valuen),  where	 each  value  is  of  the  form	 [sub-
       script]=string.	 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 declare builtin.  Individual array
       elements	may be assigned	to using the name[subscript]=value syntax  in-
       troduced	above.

       Any  element  of	 an  array may be referenced using ${name[subscript]}.
       The braces are required to avoid	conflicts with pathname	expansion.  If
       subscript  is  @	 or *, the word	expands	to all members of name.	 These
       subscripts differ only when the word appears within double quotes.   If
       the word	is double-quoted, ${name[*]} expands to	a single word with the
       value of	each array member separated by the first character of the  IFS
       special variable, and ${name[@]}	expands	each element of	name to	a sep-
       arate word.  When there are no array  members,  ${name[@]}  expands  to
       nothing.	  If the double-quoted expansion occurs	within a word, the ex-
       pansion of the first parameter is joined	with the beginning part	of the
       original	 word,	and the	expansion of the last parameter	is joined with
       the last	part of	the original word.  This is analogous to the expansion
       of  the	special	 parameters  *	and  @ (see Special Parameters above).
       ${#name[subscript]} expands to the length  of  ${name[subscript]}.   If
       subscript is * or @, the	expansion is the number	of elements in the ar-
       ray.  Referencing an array variable without a subscript	is  equivalent
       to referencing the array	with a subscript of 0.

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

       The unset builtin is used to destroy arrays.  unset name[subscript] de-
       stroys  the  array  element  at index subscript.	 Care must be taken to
       avoid unwanted side effects caused by pathname expansion.  unset	 name,
       where  name is an array,	or unset name[subscript], where	subscript is *
       or @, removes the entire	array.

       The declare, local, and readonly	builtins each accept a	-a  option  to
       specify	an indexed array and a -A option to specify an associative ar-
       ray.  If	both options are supplied,  -A	takes  precedence.   The  read
       builtin	accepts	 a  -a	option to assign a list	of words read from the
       standard	input to an array.  The	set and	declare	builtins display array
       values in a way that allows them	to be reused as	assignments.

EXPANSION
       Expansion is performed on the command line after	it has been split into
       words.  There are seven kinds of	expansion performed: brace  expansion,
       tilde  expansion,  parameter  and variable expansion, command substitu-
       tion, arithmetic	expansion, word	splitting, and pathname	expansion.

       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: process substitution.

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

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

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

       A  sequence expression takes the	form {x..y[..incr]}, where x and y are
       either integers or single characters, and incr, an optional  increment,
       is  an  integer.	 When integers are supplied, the expression expands to
       each number between x and y, inclusive.	Supplied integers may be  pre-
       fixed  with 0 to	force each term	to have	the same width.	 When either x
       or y begins with	a zero,	the shell  attempts  to	 force	all  generated
       terms  to  contain the same number of digits, zero-padding where	neces-
       sary.  When characters are supplied, the	 expression  expands  to  each
       character lexicographically between x and y, inclusive.	Note that both
       x and y must be of the same type.  When the increment is	 supplied,  it
       is  used	as the difference between each term.  The default increment is
       1 or -1 as appropriate.

       Brace expansion is performed before any other expansions, and any char-
       acters  special to other	expansions are preserved in the	result.	 It is
       strictly	textual.  Bash 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 ex-
       pression.  Any incorrectly formed brace expansion is left unchanged.  A
       { or , may be quoted with a backslash to	prevent	its  being  considered
       part  of	 a brace expression.  To avoid conflicts with parameter	expan-
       sion, the string	${ is not considered eligible for brace	expansion.

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

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

       Brace  expansion	 introduces  a	slight incompatibility with historical
       versions	of sh.	sh does	not treat opening or closing braces  specially
       when  they  appear as part of a word, and preserves them	in the output.
       Bash removes braces from	words as a  consequence	 of  brace  expansion.
       For  example,  a	word entered to	sh as file{1,2}	appears	identically in
       the output.  The	same word is output as file1 file2 after expansion  by
       bash.   If strict compatibility with sh is desired, start bash with the
       +B option or disable brace expansion with the +B	option to the set com-
       mand (see SHELL BUILTIN COMMANDS	below).

   Tilde Expansion
       If  a  word  begins  with an unquoted tilde character (`~'), all	of the
       characters preceding the	first unquoted slash (or  all  characters,  if
       there  is no unquoted slash) are	considered a tilde-prefix.  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 login name.
       If this login name is the null string, the tilde	is replaced  with  the
       value  of  the shell parameter HOME.  If	HOME 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 PWD  re-
       places  the  tilde-prefix.  If the tilde-prefix is a `~-', the value of
       the shell variable OLDPWD, if it	is set,	is substituted.	 If the	 char-
       acters  following  the tilde in the tilde-prefix	consist	of a number N,
       optionally prefixed by a	`+' or a `-',  the  tilde-prefix  is  replaced
       with the	corresponding element from the directory stack,	as it would be
       displayed by the	dirs builtin invoked with the tilde-prefix as an argu-
       ment.   If  the characters following the	tilde in the tilde-prefix con-
       sist of a number	without	a leading `+' or `-', `+' is assumed.

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

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

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

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

       ${parameter}
	      The value	of parameter is	substituted.  The braces are  required
	      when  parameter  is  a  positional  parameter with more than one
	      digit, or	when parameter is followed by a	character which	is not
	      to be interpreted	as part	of its name.

       If  the	first  character  of  parameter	is an exclamation point	(!), a
       level of	variable indirection is	introduced.  Bash uses	the  value  of
       the variable formed from	the rest of parameter as the name of the vari-
       able; this variable is then expanded and	that value is used in the rest
       of  the	substitution, rather than the value of parameter itself.  This
       is known	as indirect expansion.	The exceptions to this are the	expan-
       sions  of ${!prefix*} and ${!name[@]} described below.  The exclamation
       point must immediately follow the left brace in order to	introduce  in-
       direction.

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

       When not	performing substring expansion,	using the forms	documented be-
       low,  bash  tests  for a	parameter that is unset	or null.  Omitting the
       colon results in	a test only for	a parameter that is unset.

       ${parameter:-word}
	      Use Default Values.  If parameter	is unset or null,  the	expan-
	      sion  of word is substituted.  Otherwise,	the value of parameter
	      is substituted.
       ${parameter:=word}
	      Assign Default Values.  If parameter is unset or null,  the  ex-
	      pansion  of word is assigned to parameter.  The value of parame-
	      ter is then substituted.	Positional parameters and special  pa-
	      rameters may not be assigned to in this way.
       ${parameter:?word}
	      Display  Error if	Null or	Unset.	If parameter is	null or	unset,
	      the expansion of word (or	a message to that effect  if  word  is
	      not  present) is written to the standard error and the shell, if
	      it is not	interactive, exits.  Otherwise,	the value of parameter
	      is substituted.
       ${parameter:+word}
	      Use  Alternate Value.  If	parameter is null or unset, nothing is
	      substituted, otherwise the expansion of word is substituted.
       ${parameter:offset}
       ${parameter:offset:length}
	      Substring	Expansion.  Expands to up to length characters of  pa-
	      rameter  starting	 at  the  character  specified	by offset.  If
	      length is	omitted, expands to the	substring of parameter	start-
	      ing at the character specified by	offset.	 length	and offset are
	      arithmetic expressions (see ARITHMETIC  EVALUATION  below).   If
	      offset  evaluates	 to a number less than zero, the value is used
	      as an offset from	the end	of the value of	parameter.  If	length
	      evaluates	to a number less than zero, and	parameter is not @ and
	      not an indexed or	associative array, it  is  interpreted	as  an
	      offset from the end of the value of parameter rather than	a num-
	      ber of characters, and the expansion is the  characters  between
	      the  two offsets.	 If parameter is @, the	result is length posi-
	      tional parameters	beginning at offset.  If parameter is  an  in-
	      dexed array name subscripted by @	or *, the result is the	length
	      members of the array  beginning  with  ${parameter[offset]}.   A
	      negative	offset is taken	relative to one	greater	than the maxi-
	      mum 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
	      offset is	0, and the positional parameters are used, $0 is  pre-
	      fixed to the list.

       ${!prefix*}
       ${!prefix@}
	      Names  matching prefix.  Expands to the names of variables whose
	      names begin with prefix, separated by the	first character	of the
	      IFS  special variable.  When @ is	used and the expansion appears
	      within double quotes, each variable name expands to  a  separate
	      word.

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

       ${#parameter}
	      Parameter	 length.  The length in	characters of the value	of pa-
	      rameter is substituted.  If parameter is * or @, the value  sub-
	      stituted	is  the	number of positional parameters.  If parameter
	      is an array name subscripted by *	or @, the value	substituted is
	      the number of elements in	the array.

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

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

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

       ${parameter^pattern}
       ${parameter^^pattern}
       ${parameter,pattern}
       ${parameter,,pattern}
	      Case  modification.   This expansion modifies the	case of	alpha-
	      betic characters in parameter.  The pattern is expanded to  pro-
	      duce  a  pattern	just as	in pathname expansion.	The ^ operator
	      converts lowercase letters matching pattern to uppercase;	the  ,
	      operator	converts matching uppercase letters to lowercase.  The
	      ^^ and ,,	expansions convert each	matched	character in  the  ex-
	      panded  value; the ^ and , expansions match and convert only the
	      first character in the expanded value.  If pattern  is  omitted,
	      it  is  treated like a ?,	which matches every character.	If pa-
	      rameter is @ or *, the case modification operation is applied to
	      each  positional parameter in turn, and the expansion is the re-
	      sultant list.  If	parameter is  an  array	 variable  subscripted
	      with  @ or *, the	case modification operation is applied to each
	      member of	the array in turn, and the expansion is	the  resultant
	      list.

   Command Substitution
       Command substitution allows the output of a command to replace the com-
       mand name.  There are two forms:

	      $(command)
       or
	      `command`

       Bash performs the expansion by executing	command	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 $(cat
       file) can be replaced by	the equivalent but faster $(< file).

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

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

	      $((expression))

       The expression is treated as if it were within  double  quotes,	but  a
       double  quote inside the	parentheses is not treated specially.  All to-
       kens 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
       ARITHMETIC EVALUATION.  If expression is	invalid, bash prints a message
       indicating failure and no substitution occurs.

   Process Substitution
       Process substitution is supported on systems that support  named	 pipes
       (FIFOs)	or the /dev/fd method of naming	open files.  It	takes the form
       of <(list) or >(list).  The process list	is run with its	input or  out-
       put connected to	a FIFO or some file in /dev/fd.	 The name of this file
       is passed as an argument	to the current command as the  result  of  the
       expansion.   If the >(list) form	is used, writing to the	file will pro-
       vide input for list.  If	the <(list) form is used, the file  passed  as
       an argument should be read to obtain the	output of list.

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

   Word	Splitting
       The  shell  scans the results of	parameter expansion, command substitu-
       tion, and arithmetic expansion that did not occur within	double	quotes
       for word	splitting.

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

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

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

   Pathname Expansion
       After  word  splitting,	unless	the -f option has been set, bash scans
       each word for the characters *, ?, and [.  If one of  these  characters
       appears,	 then  the word	is regarded as a pattern, and replaced with an
       alphabetically sorted list of file names	matching the pattern.	If  no
       matching	file names are found, and the shell option nullglob is not en-
       abled, the word is left unchanged.  If the nullglob option is set,  and
       no  matches  are	found, the word	is removed.  If	the failglob shell op-
       tion is set, and	no matches are found, an error message is printed  and
       the  command  is	 not  executed.	 If the	shell option nocaseglob	is en-
       abled, the match	is performed without regard to the case	of  alphabetic
       characters.  When a pattern is used for pathname	expansion, the charac-
       ter ``.''  at the start of a name or immediately	following a slash must
       be  matched  explicitly,	 unless	the shell option dotglob is set.  When
       matching	a pathname, the	slash character	must always be matched explic-
       itly.   In  other cases,	the ``.''  character is	not treated specially.
       See the description of shopt below under	SHELL BUILTIN COMMANDS	for  a
       description  of	the  nocaseglob, nullglob, failglob, and dotglob shell
       options.

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

       Pattern Matching

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

       The special pattern characters have the following meanings:

	      *	     Matches  any string, including the	null string.  When the
		     globstar shell option is enabled, and  *  is  used	 in  a
		     pathname  expansion  context,  two	 adjacent *s used as a
		     single pattern will match all files and zero or more  di-
		     rectories	and  subdirectories.   If followed by a	/, two
		     adjacent *s will match only directories  and  subdirecto-
		     ries.
	      ?	     Matches any single	character.
	      [...]  Matches  any  one	of the enclosed	characters.  A pair of
		     characters	separated by a hyphen denotes a	range  expres-
		     sion;  any	character that sorts between those two charac-
		     ters, inclusive, using the	current	locale's collating se-
		     quence and	character set, is matched.  If the first char-
		     acter following the [ is a	!  or a	^ 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 LC_COLLATE shell variable, if set.
		     A - may be	matched	by including it	as the first  or  last
		     character in the set.  A ]	may be matched by including it
		     as	the first character in the set.

		     Within [ and ], character classes can be specified	 using
		     the syntax	[:class:], where class is one of the following
		     classes defined in	the POSIX standard:
		     alnum alpha ascii blank cntrl  digit  graph  lower	 print
		     punct space upper word xdigit
		     A character class matches any character belonging to that
		     class.  The word character	class matches letters, digits,
		     and the character _.

		     Within [ and ], an	equivalence class can be specified us-
		     ing the syntax [=c=], which matches all  characters  with
		     the  same collation weight	(as defined by the current lo-
		     cale) as the character c.

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

       Several	extended  pattern  matching  operators are recognized.	In the
       following description, a	pattern-list is	a list of one or more patterns
       separated  by  a	|.  Composite patterns may be formed using one or more
       of the following	sub-patterns:

	      ?(pattern-list)
		     Matches zero or one occurrence of the given patterns
	      *(pattern-list)
		     Matches zero or more occurrences of the given patterns
	      +(pattern-list)
		     Matches one or more occurrences of	the given patterns
	      @(pattern-list)
		     Matches one of the	given patterns

       If the extglob shell option is enabled using the	shopt builtin, follow-
       ing pattern matching operator is	recognized as well:

	      !(pattern-list)
		     Matches anything except one of the	given patterns

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

REDIRECTION
       Before  a  command  is executed,	its input and output may be redirected
       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 simple	command	or may follow a	command.  Redirections
       are processed in	the order they appear, from left to right.

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

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

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

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 >	dirlist

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

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

	      /dev/fd/fd
		     If	fd is a	valid integer, file descriptor	fd  is	dupli-
		     cated.
	      /dev/stdin
		     File descriptor 0 is duplicated.
	      /dev/stdout
		     File descriptor 1 is duplicated.
	      /dev/stderr
		     File descriptor 2 is duplicated.
	      /dev/tcp/host/port
		     If	host is	a valid	hostname or Internet address, and port
		     is	an integer port	number or service name,	bash  attempts
		     to	open a TCP connection to the corresponding socket.
	      /dev/udp/host/port
		     If	host is	a valid	hostname or Internet address, and port
		     is	an integer port	number or service name,	bash  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.

   Redirecting Input
       Redirection of input causes the file whose name results from the	expan-
       sion of word to be opened for reading on	 file  descriptor  n,  or  the
       standard	input (file descriptor 0) if n is not specified.

       The general format for redirecting input	is:

	      [n]<word

   Redirecting Output
       Redirection  of	output causes the file whose name results from the ex-
       pansion of word to be opened for	writing	on file	descriptor n,  or  the
       standard	output (file descriptor	1) if n	is not specified.  If the file
       does not	exist it is created; if	it does	exist it is truncated to  zero
       size.

       The general format for redirecting output is:

	      [n]>word

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

   Appending Redirected	Output
       Redirection of output in	this fashion causes the	file  whose  name  re-
       sults from the expansion	of word	to be opened for appending on file de-
       scriptor	n, or the standard output (file	descriptor  1)	if  n  is  not
       specified.  If the file does not	exist it is created.

       The general format for appending	output is:

	      [n]>>word

   Redirecting Standard	Output and Standard Error
       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 word.

       There  are two formats for redirecting standard output and standard er-
       ror:

	      &>word
       and
	      >&word

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

	      >word 2>&1

   Appending Standard Output and Standard Error
       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 word.

       The format for appending	standard output	and standard error is:

	      &>>word

       This is semantically equivalent to

	      >>word 2>&1

   Here	Documents
       This  type  of  redirection  instructs the shell	to read	input from the
       current source until a line containing only delimiter (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:

	      <<[-]word
		      here-document
	      delimiter

       No parameter expansion, command substitution, arithmetic	expansion,  or
       pathname	expansion is performed on word.	 If any	characters in word are
       quoted, the delimiter is	the result of quote removal on word,  and  the
       lines  in the here-document are not expanded.  If word 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 \<newline> is	ignored, and \ must be used  to	 quote
       the characters \, $, and	`.

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

   Here	Strings
       A variant of here documents, the	format is:

	      <<<word

       The word	is expanded and	supplied to the	command	on its standard	input.

   Duplicating File Descriptors
       The redirection operator

	      [n]<&word

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

       The operator

	      [n]>&word

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

   Moving File Descriptors
       The redirection operator

	      [n]<&digit-

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

       Similarly, the redirection operator

	      [n]>&digit-

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

   Opening File	Descriptors for	Reading	and Writing
       The redirection operator

	      [n]<>word

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

ALIASES
       Aliases	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 alias and unalias builtin
       commands	(see SHELL BUILTIN COMMANDS below).  The first	word  of  each
       simple  command,	if unquoted, is	checked	to see if it has an alias.  If
       so, that	word is	replaced by the	text of	the alias.  The	characters  /,
       $,  `,  and = and any of	the shell metacharacters 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 ls to ls  -F,  for	instance,  and
       bash  does  not try to recursively expand the replacement text.	If the
       last character of the alias value is a blank,  then  the	 next  command
       word following the alias	is also	checked	for alias expansion.

       Aliases are created and listed with the alias command, and removed with
       the unalias command.

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

       Aliases are not expanded	when the shell is not interactive, unless  the
       expand_aliases  shell option is set using shopt (see the	description of
       shopt under SHELL BUILTIN COMMANDS below).

       The rules concerning the	definition and use  of	aliases	 are  somewhat
       confusing.   Bash  always reads at least	one complete line of input be-
       fore 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 compound com-
       mand.  As a consequence,	aliases	defined	in a function are  not	avail-
       able  until  after  that	 function is executed.	To be safe, always put
       alias definitions on a separate line, and do not	use alias in  compound
       commands.

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

FUNCTIONS
       A  shell	 function,  defined  as	 described  above under	SHELL GRAMMAR,
       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 in-
       terpret them (contrast this with	the  execution	of  a  shell  script).
       When  a	function is executed, the arguments to the function become the
       positional parameters during its	execution.  The	special	parameter # is
       updated	to reflect the change.	Special	parameter 0 is unchanged.  The
       first element of	the FUNCNAME 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 be-
       tween a function	and its	caller with these exceptions:  the  DEBUG  and
       RETURN  traps  (see  the	 description  of  the trap builtin under SHELL
       BUILTIN COMMANDS	below) are not inherited unless	the function has  been
       given  the  trace attribute (see	the description	of the declare builtin
       below) or the -o	functrace shell	option has been	enabled	with  the  set
       builtin	(in  which  case  all  functions  inherit the DEBUG and	RETURN
       traps), and the ERR trap	is not inherited unless	the -o errtrace	 shell
       option has been enabled.

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

       The  FUNCNEST  variable,	 if set	to a numeric value greater than	0, de-
       fines a maximum function	nesting	level.	Function invocations that  ex-
       ceed the	limit cause the	entire command to abort.

       If  the	builtin	command	return 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 RETURN trap is executed be-
       fore execution resumes.	When a function	completes, the values  of  the
       positional  parameters  and the special parameter # are restored	to the
       values they had prior to	the function's execution.

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

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

ARITHMETIC EVALUATION
       The shell allows	arithmetic expressions to be evaluated,	under  certain
       circumstances  (see the let and declare builtin commands	and Arithmetic
       Expansion).  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.

       id++ id--
	      variable post-increment and post-decrement
       ++id --id
	      variable pre-increment and pre-decrement
       - +    unary minus and plus
       ! ~    logical and bitwise negation
       **     exponentiation
       * / %  multiplication, division,	remainder
       + -    addition,	subtraction
       << >>  left and right bitwise shifts
       <= >= < >
	      comparison
       == !=  equality and inequality
       &      bitwise AND
       ^      bitwise exclusive	OR
       |      bitwise OR
       &&     logical AND
       ||     logical OR
       expr?expr:expr
	      conditional operator
       = *= /= %= += -=	<<= >>=	&= ^= |=
	      assignment
       expr1 , expr2
	      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 integer
       attribute using declare -i 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
       [base#]n, where the optional base is a decimal number between 2 and  64
       representing  the  arithmetic base, and n is a number in	that base.  If
       base# is	omitted, then base 10 is used.	The digits greater than	9  are
       represented  by the lowercase letters, the uppercase letters, @,	and _,
       in that order.  If base is less than or equal to	36, lowercase and  up-
       percase	letters	 may  be used interchangeably to represent numbers be-
       tween 10	and 35.

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

CONDITIONAL EXPRESSIONS
       Conditional expressions are used	by the [[  compound  command  and  the
       test  and [ builtin commands to test file attributes and	perform	string
       and arithmetic comparisons.  Expressions	are formed from	the  following
       unary  or  binary  primaries.   If any file argument to one of the pri-
       maries is of the	form /dev/fd/n,	then file descriptor n is checked.  If
       the  file  argument  to	one  of	 the  primaries	 is one	of /dev/stdin,
       /dev/stdout, or /dev/stderr, file descriptor 0, 1, or 2,	 respectively,
       is checked.

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

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

       -a file
	      True if file exists.
       -b file
	      True if file exists and is a block special file.
       -c file
	      True if file exists and is a character special file.
       -d file
	      True if file exists and is a directory.
       -e file
	      True if file exists.
       -f file
	      True if file exists and is a regular file.
       -g file
	      True if file exists and is set-group-id.
       -h file
	      True if file exists and is a symbolic link.
       -k file
	      True if file exists and its ``sticky'' bit is set.
       -p file
	      True if file exists and is a named pipe (FIFO).
       -r file
	      True if file exists and is readable.
       -s file
	      True if file exists and has a size greater than zero.
       -t fd  True if file descriptor fd is open and refers to a terminal.
       -u file
	      True if file exists and its set-user-id bit is set.
       -w file
	      True if file exists and is writable.
       -x file
	      True if file exists and is executable.
       -G file
	      True if file exists and is owned by the effective	group id.
       -L file
	      True if file exists and is a symbolic link.
       -N file
	      True if file exists and has been	modified  since	 it  was  last
	      read.
       -O file
	      True if file exists and is owned by the effective	user id.
       -S file
	      True if file exists and is a socket.
       file1 -ef file2
	      True  if file1 and file2 refer to	the same device	and inode num-
	      bers.
       file1 -nt file2
	      True if file1 is newer (according	 to  modification  date)  than
	      file2, or	if file1 exists	and file2 does not.
       file1 -ot file2
	      True  if file1 is	older than file2, or if	file2 exists and file1
	      does not.
       -o optname
	      True if the shell	option optname is enabled.  See	 the  list  of
	      options  under  the  description	of  the	 -o  option to the set
	      builtin below.
       -v varname
	      True if the shell	variable varname is set	(has been  assigned  a
	      value).
       -z string
	      True if the length of string is zero.
       string
       -n string
	      True if the length of string is non-zero.

       string1 == string2
       string1 = string2
	      True  if	the strings are	equal.	= should be used with the test
	      command for POSIX	conformance.

       string1 != string2
	      True if the strings are not equal.

       string1 < string2
	      True if string1 sorts before string2 lexicographically.

       string1 > string2
	      True if string1 sorts after string2 lexicographically.

       arg1 OP arg2
	      OP is one	of -eq,	-ne, -lt, -le, -gt, or -ge.  These  arithmetic
	      binary  operators	return true if arg1 is equal to, not equal to,
	      less than, less than or equal to,	greater	than, or greater  than
	      or  equal	 to arg2, respectively.	 Arg1 and arg2 may be positive
	      or negative integers.

SIMPLE COMMAND EXPANSION
       When a simple command is	executed, the shell performs the following ex-
       pansions, 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 REDIRECTION.

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

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

       If no command name results, redirections	are performed, but do not  af-
       fect  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.

COMMAND	EXECUTION
       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 FUNCTIONS.  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,	bash searches each element of the PATH for  a  directory  con-
       taining an executable file by that name.	 Bash uses a hash table	to re-
       member the full pathnames of executable files  (see  hash  under	 SHELL
       BUILTIN	COMMANDS  below).  A full search of the	directories in PATH 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 command_not_found_handle.	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 shell script,  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 hash below  un-
       der SHELL BUILTIN COMMANDS) are retained	by the child.

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

COMMAND	EXECUTION ENVIRONMENT
       The  shell  has an execution environment, which consists	of the follow-
       ing:

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

       o      the  current  working directory as set by	cd, pushd, or popd, or
	      inherited	by the shell at	invocation

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

       o      current traps set	by trap

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

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

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

       o      options enabled by shopt

       o      shell aliases defined with alias

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

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

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

       o      the current working directory

       o      the file creation	mode mask

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

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

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

       Command substitution, commands grouped with parentheses,	and  asynchro-
       nous commands are invoked in a subshell environment that	is a duplicate
       of the shell environment, except	that traps caught by the shell are re-
       set  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  -e	option	from  the  parent shell.  When not in posix mode, bash
       clears the -e option in such subshells.

       If a command is followed	by a & and job control is not active, the  de-
       fault standard input for	the command is the empty file /dev/null.  Oth-
       erwise, the invoked command inherits the	file descriptors of the	 call-
       ing shell as modified by	redirections.

ENVIRONMENT
       When  a	program	 is invoked it is given	an array of strings called the
       environment.   This  is	a  list	 of  name-value	 pairs,	 of  the  form
       name=value.

       The  shell provides several ways	to manipulate the environment.	On in-
       vocation, the shell scans its own environment and creates  a  parameter
       for  each name found, automatically marking it for export to child pro-
       cesses.	Executed commands inherit the environment.  The	export and de-
       clare  -x  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, re-
       placing 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	 unset	command,  plus
       any additions via the export and	declare	-x commands.

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

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

       When bash invokes an external command, the variable _  is  set  to  the
       full  file  name	of the command and passed to that command in its envi-
       ronment.

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

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

       If a command is not found, the child process created to execute it  re-
       turns  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 (true) if successful, and
       non-zero	(false)	if an error occurs while they execute.	 All  builtins
       return an exit status of	2 to indicate incorrect	usage.

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

SIGNALS
       When  bash  is  interactive,  in	 the  absence of any traps, it ignores
       SIGTERM (so that	kill 0 does not	kill an	interactive shell), and	SIGINT
       is  caught and handled (so that the wait	builtin	is interruptible).  In
       all cases, bash ignores SIGQUIT.	 If job	control	is in effect, bash ig-
       nores SIGTTIN, SIGTTOU, and SIGTSTP.

       Non-builtin commands run	by bash	have signal handlers set to the	values
       inherited by the	shell from its parent.	When job control is not	in ef-
       fect,  asynchronous  commands  ignore SIGINT and	SIGQUIT	in addition to
       these inherited handlers.  Commands run as a result of command  substi-
       tution ignore the keyboard-generated job	control	signals	SIGTTIN, SIGT-
       TOU, and	SIGTSTP.

       The shell exits by default upon receipt of a SIGHUP.   Before  exiting,
       an  interactive	shell  resends	the  SIGHUP  to	 all  jobs, running or
       stopped.	 Stopped jobs are sent SIGCONT to ensure that they receive the
       SIGHUP.	 To  prevent the shell from sending the	signal to a particular
       job, it should be removed from the jobs table with the  disown  builtin
       (see  SHELL BUILTIN COMMANDS below) or marked to	not receive SIGHUP us-
       ing disown -h.

       If the huponexit	shell option has been set with	shopt,	bash  sends  a
       SIGHUP to all jobs when an interactive login shell exits.

       If  bash	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 bash is waiting for an asynchronous command via
       the wait	builtin, the reception of a signal for which a trap  has  been
       set will	cause the wait builtin to return immediately with an exit sta-
       tus greater than	128, immediately after which the trap is executed.

JOB CONTROL
       Job control refers to the ability to selectively	stop (suspend) the ex-
       ecution	of  processes and continue (resume) their execution at a later
       point.  A user typically	employs	this facility via an  interactive  in-
       terface	supplied  jointly  by  the  operating system kernel's terminal
       driver and bash.

       The shell associates a job with each pipeline.  It  keeps  a  table  of
       currently  executing  jobs,  which may be listed	with the jobs command.
       When bash starts	a job asynchronously (in the background), 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.  Bash
       uses the	job 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 current terminal process
       group ID.  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 SIGINT.  These	processes are said  to	be  in
       the  foreground.	 Background processes are those	whose process group ID
       differs from the	terminal's; such processes are immune to keyboard-gen-
       erated signals.	Only foreground	processes are allowed to read from or,
       if the user so specifies	with  stty  tostop,  write  to	the  terminal.
       Background  processes  which  attempt  to read from (write to when stty
       tostop is in effect) the	terminal are sent a SIGTTIN  (SIGTTOU)	signal
       by  the	kernel's  terminal  driver, which, unless caught, suspends the
       process.

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

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

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

       The shell learns	immediately whenever a job changes  state.   Normally,
       bash 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
       option to the set builtin command is enabled, bash reports such changes
       immediately.  Any trap on SIGCHLD is executed for each child  that  ex-
       its.

       If  an  attempt to exit bash is made while jobs are stopped (or,	if the
       checkjobs shell option has been enabled using the shopt	builtin,  run-
       ning), the shell	prints a warning message, and, if the checkjobs	option
       is enabled, lists the jobs and their statuses.  The  jobs  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.

PROMPTING
       When executing interactively, bash displays the primary prompt PS1 when
       it is ready to read a command, and the secondary	 prompt	 PS2  when  it
       needs  more  input  to  complete	 a  command.  Bash allows these	prompt
       strings to be customized	by inserting  a	 number	 of  backslash-escaped
       special characters that are decoded as follows:
	      \a     an	ASCII bell character (07)
	      \d     the  date	in "Weekday Month Date"	format (e.g., "Tue May
		     26")
	      \D{format}
		     the format	is passed to strftime(3) and the result	is in-
		     serted into the prompt string; an empty format results in
		     a locale-specific time representation.   The  braces  are
		     required
	      \e     an	ASCII escape character (033)
	      \h     the hostname up to	the first `.'
	      \H     the hostname
	      \j     the number	of jobs	currently managed by the shell
	      \l     the basename of the shell's terminal device name
	      \n     newline
	      \r     carriage return
	      \s     the  name	of  the	shell, the basename of $0 (the portion
		     following the final slash)
	      \t     the current time in 24-hour HH:MM:SS format
	      \T     the current time in 12-hour HH:MM:SS format
	      \@     the current time in 12-hour am/pm format
	      \A     the current time in 24-hour HH:MM format
	      \u     the username of the current user
	      \v     the version of bash (e.g.,	2.00)
	      \V     the release of bash, version + patch level	(e.g., 2.00.0)
	      \w     the current working  directory,  with  $HOME  abbreviated
		     with  a tilde (uses the value of the PROMPT_DIRTRIM vari-
		     able)
	      \W     the basename of the current working directory, with $HOME
		     abbreviated with a	tilde
	      \!     the history number	of this	command
	      \#     the command number	of this	command
	      \$     if	the effective UID is 0,	a #, otherwise a $
	      \nnn   the character corresponding to the	octal number nnn
	      \\     a backslash
	      \[     begin  a sequence of non-printing characters, which could
		     be	used to	embed a	terminal  control  sequence  into  the
		     prompt
	      \]     end a sequence of non-printing characters

       The  command  number  and the history number are	usually	different: the
       history number of a command is its position in the history list,	 which
       may  include  commands  restored	from the history file (see HISTORY be-
       low), while the command number is the position in the sequence of  com-
       mands  executed	during the current shell session.  After the string is
       decoded,	it is expanded via parameter expansion,	command	 substitution,
       arithmetic  expansion,  and  quote removal, subject to the value	of the
       promptvars shell	option (see the	description of the shopt command under
       SHELL BUILTIN COMMANDS below).

READLINE
       This  is	 the library that handles reading input	when using an interac-
       tive shell, unless the --noediting option is given at shell invocation.
       Line editing is also used when using the	-e option to the read 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 -o	emacs or -o  vi	 options  to  the  set
       builtin	(see  SHELL BUILTIN COMMANDS below).  To turn off line editing
       after the shell is running, use the +o emacs or +o vi  options  to  the
       set builtin.

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

       Readline	commands may be	given numeric arguments, 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., kill-line) 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 killing text, the	text deleted is	 saved
       for possible future retrieval (yanking).	 The killed text is saved in a
       kill ring.  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.

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

       The default key-bindings	may be changed with an	inputrc	 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 inputrc would make M-C-u execute the readline command univer-
       sal-argument.

       The following symbolic character	names  are  recognized:	 RUBOUT,  DEL,
       ESC, LFD, NEWLINE, RET, RETURN, SPC, SPACE, and TAB.

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

   Readline Key	Bindings
       The syntax for controlling key bindings in the inputrc 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 Meta- or
       Control-	prefixes, or as	a key sequence.

       When using the form keyname:function-name or macro, keyname is the name
       of a key	spelled	out in English.	 For example:

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

       In  the above example, C-u is bound to the function universal-argument,
       M-DEL is	bound to the function backward-kill-word, and C-o is bound  to
       run  the	macro expressed	on the right hand side (that is, to insert the
       text ``>	output'' into the line).

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

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

       In this example,	C-u is again bound to the function universal-argument.
       C-x  C-r	is bound to the	function re-read-init-file, and	ESC [ 1	1 ~ is
       bound to	insert the text	``Function Key 1''.

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

       In addition to the GNU Emacs style escape sequences, a  second  set  of
       backslash escapes is available:
	      \a     alert (bell)
	      \b     backspace
	      \d     delete
	      \f     form feed
	      \n     newline
	      \r     carriage return
	      \t     horizontal	tab
	      \v     vertical tab
	      \nnn   the  eight-bit  character	whose value is the octal value
		     nnn (one to three digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (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 '.

       Bash  allows the	current	readline key bindings to be displayed or modi-
       fied with the bind builtin command.  The	editing	mode may  be  switched
       during  interactive  use	by using the -o	option to the set builtin com-
       mand (see SHELL BUILTIN COMMANDS	below).

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

	      set variable-name	value

       Except where noted, readline variables can take the values  On  or  Off
       (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 On.  All other values	are equivalent
       to Off.	The variables and their	default	values are:

       bell-style (audible)
	      Controls what happens when readline wants	to ring	 the  terminal
	      bell.  If	set to none, readline never rings the bell.  If	set to
	      visible, readline	uses a visible bell if one is  available.   If
	      set to audible, readline attempts	to ring	the terminal's bell.
       bind-tty-special-chars (On)
	      If  set  to On, readline attempts	to bind	the control characters
	      treated specially	by the kernel's	terminal driver	to their read-
	      line equivalents.
       comment-begin (``#'')
	      The  string  that	 is  inserted when the readline	insert-comment
	      command is executed.  This command is bound to M-# in emacs mode
	      and to # in vi command mode.
       completion-ignore-case (Off)
	      If set to	On, readline performs filename matching	and completion
	      in a case-insensitive fashion.
       completion-prefix-display-length	(0)
	      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.
       completion-query-items (100)
	      This determines when the user is queried about viewing the  num-
	      ber  of  possible	 completions generated by the possible-comple-
	      tions 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.
       convert-meta (On)
	      If set to	On, 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
	      meta prefix).
       disable-completion (Off)
	      If set to	On, readline will inhibit word completion.  Completion
	      characters will be inserted into the line	as if  they  had  been
	      mapped to	self-insert.
       editing-mode (emacs)
	      Controls whether readline	begins with a set of key bindings sim-
	      ilar to Emacs or vi.  editing-mode can be	set to either emacs or
	      vi.
       echo-control-characters (On)
	      When  set	to On, on operating systems that indicate they support
	      it, readline echoes a character corresponding to a signal	gener-
	      ated from	the keyboard.
       enable-keypad (Off)
	      When set to On, readline will try	to enable the application key-
	      pad when it is called.  Some systems need	this to	enable the ar-
	      row keys.
       enable-meta-key (On)
	      When  set	 to  On, readline will try to enable any meta modifier
	      key the terminal claims to support when it is called.   On  many
	      terminals, the meta key is used to send eight-bit	characters.
       expand-tilde (Off)
	      If  set  to  On,	tilde expansion	is performed when readline at-
	      tempts word completion.
       history-preserve-point (Off)
	      If set to	On, the	history	code attempts to place	point  at  the
	      same  location on	each history line retrieved with previous-his-
	      tory or next-history.
       history-size (0)
	      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.
       horizontal-scroll-mode (Off)
	      When set to On, 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.
       input-meta (Off)
	      If  set to On, readline will enable eight-bit input (that	is, it
	      will not strip the high bit from the characters it  reads),  re-
	      gardless	of  what the terminal claims it	can support.  The name
	      meta-flag	is a synonym for this variable.
       isearch-terminators (``C-[C-J'')
	      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 ESC and C-J will terminate an incremental search.
       keymap (emacs)
	      Set  the current readline	keymap.	 The set of valid keymap names
	      is emacs,	emacs-standard,	emacs-meta,  emacs-ctlx,  vi,  vi-com-
	      mand,  and  vi-insert.  vi is equivalent to vi-command; emacs is
	      equivalent to emacs-standard.  The default value is  emacs;  the
	      value of editing-mode also affects the default keymap.
       mark-directories	(On)
	      If set to	On, completed directory	names have a slash appended.
       mark-modified-lines (Off)
	      If  set  to  On,	history	lines that have	been modified are dis-
	      played with a preceding asterisk (*).
       mark-symlinked-directories (Off)
	      If set to	On, completed names which are symbolic links to	direc-
	      tories  have  a slash appended (subject to the value of mark-di-
	      rectories).
       match-hidden-files (On)
	      This variable, when set to On, causes readline  to  match	 files
	      whose  names  begin  with	 a  `.'	(hidden	files) when performing
	      filename completion.  If set to Off, the	leading	 `.'  must  be
	      supplied by the user in the filename to be completed.
       menu-complete-display-prefix (Off)
	      If  set to On, menu completion displays the common prefix	of the
	      list of possible completions (which may be empty)	before cycling
	      through the list.
       output-meta (Off)
	      If  set  to On, readline will display characters with the	eighth
	      bit set directly rather than as a	meta-prefixed escape sequence.
       page-completions	(On)
	      If set to	On, readline uses an internal more-like	pager to  dis-
	      play a screenful of possible completions at a time.
       print-completions-horizontally (Off)
	      If  set  to  On,	readline will display completions with matches
	      sorted horizontally in alphabetical order, rather	than down  the
	      screen.
       revert-all-at-newline (Off)
	      If  set  to  On, readline	will undo all changes to history lines
	      before returning when accept-line	is executed.  By default, his-
	      tory  lines  may	be  modified  and retain individual undo lists
	      across calls to readline.
       show-all-if-ambiguous (Off)
	      This alters the default behavior of  the	completion  functions.
	      If set to	On, words which	have more than one possible completion
	      cause the	matches	to be listed immediately  instead  of  ringing
	      the bell.
       show-all-if-unmodified (Off)
	      This  alters the default behavior	of the completion functions in
	      a	fashion	similar	to show-all-if-ambiguous.  If set to On, 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 in-
	      stead of ringing the bell.
       skip-completed-text (Off)
	      If set to	On, this alters	the default completion	behavior  when
	      inserting	 a  single match into the line.	 It's only active when
	      performing completion in the middle  of  a  word.	  If  enabled,
	      readline	does  not  insert  characters from the completion that
	      match characters after point in the  word	 being	completed,  so
	      portions of the word following the cursor	are not	duplicated.
       visible-stats (Off)
	      If  set to On, a character denoting a file's type	as reported by
	      stat(2) is appended to the filename when listing	possible  com-
	      pletions.

   Readline Conditional	Constructs
       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.

       $if    The $if 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.

	      mode   The  mode=	 form  of  the	$if  directive is used to test
		     whether readline is in emacs or vi	 mode.	 This  may  be
		     used  in conjunction with the set keymap command, for in-
		     stance,  to  set  bindings	 in  the  emacs-standard   and
		     emacs-ctlx	 keymaps  only	if readline is starting	out in
		     emacs mode.

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

	      application
		     The application construct is used to include application-
		     specific  settings.   Each	program	using the readline li-
		     brary sets	the application	name,  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:

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

       $endif This command, as seen in the previous example, terminates	an $if
	      command.

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

       $include
	      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 /etc/inputrc:

	      $include	/etc/inputrc

   Searching
       Readline	 provides  commands  for searching through the command history
       (see HISTORY below) for lines containing	a specified string.  There are
       two search modes: incremental and non-incremental.

       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	isearch-terminators 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 newline 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.

   Readline Command Names
       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, point refers to the current cursor position, and mark refers  to
       a  cursor position saved	by the set-mark	command.  The text between the
       point and mark is referred to as	the region.

   Commands for	Moving
       beginning-of-line (C-a)
	      Move to the start	of the current line.
       end-of-line (C-e)
	      Move to the end of the line.
       forward-char (C-f)
	      Move forward a character.
       backward-char (C-b)
	      Move back	a character.
       forward-word (M-f)
	      Move forward to the end of the next word.	 Words are composed of
	      alphanumeric characters (letters and digits).
       backward-word (M-b)
	      Move  back  to the start of the current or previous word.	 Words
	      are composed of alphanumeric characters (letters and digits).
       shell-forward-word
	      Move forward to the end of the next word.	 Words	are  delimited
	      by non-quoted shell metacharacters.
       shell-backward-word
	      Move  back  to the start of the current or previous word.	 Words
	      are delimited by non-quoted shell	metacharacters.
       clear-screen (C-l)
	      Clear the	screen leaving the current line	 at  the  top  of  the
	      screen.	With  an  argument,  refresh  the current line without
	      clearing the screen.
       redraw-current-line
	      Refresh the current line.

   Commands for	Manipulating the History
       accept-line (Newline, Return)
	      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 HISTCONTROL variable.  If the line	is a modified  history
	      line, then restore the history line to its original state.
       previous-history	(C-p)
	      Fetch the	previous command from the history list,	moving back in
	      the list.
       next-history (C-n)
	      Fetch the	next command from the history list, moving forward  in
	      the list.
       beginning-of-history (M-<)
	      Move to the first	line in	the history.
       end-of-history (M->)
	      Move  to	the end	of the input history, i.e., the	line currently
	      being entered.
       reverse-search-history (C-r)
	      Search backward starting at the current  line  and  moving  `up'
	      through  the  history  as	 necessary.   This  is	an incremental
	      search.
       forward-search-history (C-s)
	      Search forward starting at the current line  and	moving	`down'
	      through  the  history  as	 necessary.   This  is	an incremental
	      search.
       non-incremental-reverse-search-history (M-p)
	      Search backward through the history starting at the current line
	      using  a	non-incremental	 search	 for  a	string supplied	by the
	      user.
       non-incremental-forward-search-history (M-n)
	      Search forward  through  the  history  using  a  non-incremental
	      search for a string supplied by the user.
       history-search-forward
	      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.
       history-search-backward
	      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.
       yank-nth-arg (M-C-y)
	      Insert  the  first argument to the previous command (usually the
	      second word on the previous line)	at point.  With	an argument n,
	      insert  the nth word from	the previous command (the words	in the
	      previous command begin with word 0).  A  negative	 argument  in-
	      serts  the  nth word from	the end	of the previous	command.  Once
	      the argument n is	computed, the argument is extracted as if  the
	      "!n" history expansion had been specified.
       yank-last-arg (M-., M-_)
	      Insert  the last argument	to the previous	command	(the last word
	      of the previous history entry).  With a numeric argument,	behave
	      exactly  like  yank-nth-arg.   Successive	calls to yank-last-arg
	      move back	through	the history list, inserting the	last word  (or
	      the  word	 specified  by the argument to the first call) of each
	      line in turn.  Any numeric argument supplied to these successive
	      calls  determines	 the direction to move through the history.  A
	      negative argument	switches the  direction	 through  the  history
	      (back or forward).  The history expansion	facilities are used to
	      extract the last argument, as if the "!$"	history	expansion  had
	      been specified.
       shell-expand-line (M-C-e)
	      Expand the line as the shell does.  This performs	alias and his-
	      tory expansion as	well as	all of the shell word expansions.  See
	      HISTORY EXPANSION	below for a description	of history expansion.
       history-expand-line (M-^)
	      Perform  history expansion on the	current	line.  See HISTORY EX-
	      PANSION below for	a description of history expansion.
       magic-space
	      Perform history expansion	on  the	 current  line	and  insert  a
	      space.  See HISTORY EXPANSION below for a	description of history
	      expansion.
       alias-expand-line
	      Perform alias expansion on the current line.  See	ALIASES	 above
	      for a description	of alias expansion.
       history-and-alias-expand-line
	      Perform history and alias	expansion on the current line.
       insert-last-argument (M-., M-_)
	      A	synonym	for yank-last-arg.
       operate-and-get-next (C-o)
	      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.
       edit-and-execute-command	(C-xC-e)
	      Invoke  an  editor  on the current command line, and execute the
	      result as	shell commands.	 Bash attempts to invoke $VISUAL, $ED-
	      ITOR, and	emacs as the editor, in	that order.

   Commands for	Changing Text
       delete-char (C-d)
	      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 delete-char, then return	EOF.
       backward-delete-char (Rubout)
	      Delete  the  character  behind the cursor.  When given a numeric
	      argument,	save the deleted text on the kill ring.
       forward-backward-delete-char
	      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.
       quoted-insert (C-q, C-v)
	      Add the next character typed to the line verbatim.  This is  how
	      to insert	characters like	C-q, for example.
       tab-insert (C-v TAB)
	      Insert a tab character.
       self-insert (a, b, A, 1,	!, ...)
	      Insert the character typed.
       transpose-chars (C-t)
	      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.
       transpose-words (M-t)
	      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.
       upcase-word (M-u)
	      Uppercase	the current (or	following) word.  With a negative  ar-
	      gument, uppercase	the previous word, but do not move point.
       downcase-word (M-l)
	      Lowercase	 the current (or following) word.  With	a negative ar-
	      gument, lowercase	the previous word, but do not move point.
       capitalize-word (M-c)
	      Capitalize the current (or following) word.  With	a negative ar-
	      gument, capitalize the previous word, but	do not move point.
       overwrite-mode
	      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 emacs mode; vi mode does overwrite differently.  Each  call
	      to readline() starts in insert mode.  In overwrite mode, charac-
	      ters bound to self-insert	replace	the text at point rather  than
	      pushing  the  text  to  the  right.   Characters	bound to back-
	      ward-delete-char replace	the  character	before	point  with  a
	      space.  By default, this command is unbound.

   Killing and Yanking
       kill-line (C-k)
	      Kill the text from point to the end of the line.
       backward-kill-line (C-x Rubout)
	      Kill backward to the beginning of	the line.
       unix-line-discard (C-u)
	      Kill  backward  from  point  to  the beginning of	the line.  The
	      killed text is saved on the kill-ring.
       kill-whole-line
	      Kill all characters on the current line, no matter  where	 point
	      is.
       kill-word (M-d)
	      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 forward-word.
       backward-kill-word (M-Rubout)
	      Kill  the	 word  behind  point.  Word boundaries are the same as
	      those used by backward-word.
       shell-kill-word (M-d)
	      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 shell-forward-word.
       shell-backward-kill-word	(M-Rubout)
	      Kill the word behind point.  Word	boundaries  are	 the  same  as
	      those used by shell-backward-word.
       unix-word-rubout	(C-w)
	      Kill  the	 word behind point, using white	space as a word	bound-
	      ary.  The	killed text is saved on	the kill-ring.
       unix-filename-rubout
	      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.
       delete-horizontal-space (M-\)
	      Delete all spaces	and tabs around	point.
       kill-region
	      Kill the text in the current region.
       copy-region-as-kill
	      Copy the text in the region to the kill buffer.
       copy-backward-word
	      Copy the word before point to the	kill buffer.  The word	bound-
	      aries are	the same as backward-word.
       copy-forward-word
	      Copy  the	 word  following  point	 to the	kill buffer.  The word
	      boundaries are the same as forward-word.
       yank (C-y)
	      Yank the top of the kill ring into the buffer at point.
       yank-pop	(M-y)
	      Rotate the kill ring, and	yank the new top.  Only	works  follow-
	      ing yank or yank-pop.

   Numeric Arguments
       digit-argument (M-0, M-1, ..., M--)
	      Add  this	digit to the argument already accumulating, or start a
	      new argument.  M-- starts	a negative argument.
       universal-argument
	      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 universal-argument again ends the nu-
	      meric argument, but is otherwise ignored.	 As a special case, if
	      this command is immediately followed by a	character that is nei-
	      ther a digit or minus sign, the argument count for the next com-
	      mand  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.

   Completing
       complete	(TAB)
	      Attempt to perform completion on the text	 before	 point.	  Bash
	      attempts completion treating the text as a variable (if the text
	      begins with $), username (if the text begins with	 ~),  hostname
	      (if  the	text begins with @), or	command	(including aliases and
	      functions) in turn.  If none of these produces a match, filename
	      completion is attempted.
       possible-completions (M-?)
	      List the possible	completions of the text	before point.
       insert-completions (M-*)
	      Insert  all completions of the text before point that would have
	      been generated by	possible-completions.
       menu-complete
	      Similar to complete, but replaces	the word to be completed  with
	      a	 single	match from the list of possible	completions.  Repeated
	      execution	of menu-complete 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
	      bell-style) and the original text	is restored.  An argument of n
	      moves n positions	forward	in the list of matches;	a negative ar-
	      gument may be used to move backward through the list.  This com-
	      mand is intended to be bound to TAB, but is unbound by default.
       menu-complete-backward
	      Identical	to menu-complete, but moves backward through the  list
	      of  possible  completions,  as if	menu-complete had been given a
	      negative argument.  This command is unbound by default.
       delete-char-or-list
	      Deletes the character under the cursor if	not at	the  beginning
	      or  end  of  the	line (like delete-char).  If at	the end	of the
	      line, behaves identically	to possible-completions.  This command
	      is unbound by default.
       complete-filename (M-/)
	      Attempt filename completion on the text before point.
       possible-filename-completions (C-x /)
	      List the possible	completions of the text	before point, treating
	      it as a filename.
       complete-username (M-~)
	      Attempt completion on the	text before point, treating  it	 as  a
	      username.
       possible-username-completions (C-x ~)
	      List the possible	completions of the text	before point, treating
	      it as a username.
       complete-variable (M-$)
	      Attempt completion on the	text before point, treating  it	 as  a
	      shell variable.
       possible-variable-completions (C-x $)
	      List the possible	completions of the text	before point, treating
	      it as a shell variable.
       complete-hostname (M-@)
	      Attempt completion on the	text before point, treating  it	 as  a
	      hostname.
       possible-hostname-completions (C-x @)
	      List the possible	completions of the text	before point, treating
	      it as a hostname.
       complete-command	(M-!)
	      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.
       possible-command-completions (C-x !)
	      List the possible	completions of the text	before point, treating
	      it as a command name.
       dynamic-complete-history	(M-TAB)
	      Attempt completion on the	text before point, comparing the  text
	      against  lines  from  the	 history  list for possible completion
	      matches.
       dabbrev-expand
	      Attempt menu completion on the text before point,	comparing  the
	      text against lines from the history list for possible completion
	      matches.
       complete-into-braces (M-{)
	      Perform filename completion and insert the list of possible com-
	      pletions	enclosed within	braces so the list is available	to the
	      shell (see Brace Expansion above).

   Keyboard Macros
       start-kbd-macro (C-x ()
	      Begin saving the characters  typed  into	the  current  keyboard
	      macro.
       end-kbd-macro (C-x ))
	      Stop saving the characters typed into the	current	keyboard macro
	      and store	the definition.
       call-last-kbd-macro (C-x	e)
	      Re-execute the last keyboard macro defined, by making the	 char-
	      acters in	the macro appear as if typed at	the keyboard.

   Miscellaneous
       re-read-init-file (C-x C-r)
	      Read  in	the  contents of the inputrc file, and incorporate any
	      bindings or variable assignments found there.
       abort (C-g)
	      Abort the	current	editing	command	and ring the  terminal's  bell
	      (subject to the setting of bell-style).
       do-uppercase-version (M-a, M-b, M-x, ...)
	      If  the  metafied	character x is lowercase, run the command that
	      is bound to the corresponding uppercase character.
       prefix-meta (ESC)
	      Metafy the next character	typed.	ESC f is equivalent to Meta-f.
       undo (C-_, C-x C-u)
	      Incremental undo,	separately remembered for each line.
       revert-line (M-r)
	      Undo all changes made to this line.  This	is like	executing  the
	      undo  command  enough  times  to	return the line	to its initial
	      state.
       tilde-expand (M-&)
	      Perform tilde expansion on the current word.
       set-mark	(C-@, M-<space>)
	      Set the mark to the point.  If a numeric argument	 is  supplied,
	      the mark is set to that position.
       exchange-point-and-mark (C-x C-x)
	      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.
       character-search	(C-])
	      A	character is read and point is moved to	the next occurrence of
	      that character.  A negative count	searches for  previous	occur-
	      rences.
       character-search-backward (M-C-])
	      A	 character  is	read and point is moved	to the previous	occur-
	      rence of that character.	A negative count searches  for	subse-
	      quent occurrences.
       skip-csi-sequence
	      Read  enough  characters to consume a multi-key sequence such as
	      those defined for	keys like Home and End.	 Such sequences	 begin
	      with a Control Sequence Indicator	(CSI), usually ESC-[.  If this
	      sequence is bound	to "\[", keys producing	 such  sequences  will
	      have  no	effect	unless explicitly bound	to a readline command,
	      instead of inserting stray characters into the  editing  buffer.
	      This is unbound by default, but usually bound to ESC-[.
       insert-comment (M-#)
	      Without  a  numeric  argument,  the  value  of the readline com-
	      ment-begin 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 comment-begin, the value is inserted,	other-
	      wise the characters in comment-begin 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	 comment-begin
	      causes  this  command  to	make the current line a	shell comment.
	      If a numeric argument causes the comment	character  to  be  re-
	      moved, the line will be executed by the shell.
       glob-complete-word (M-g)
	      The  word	 before	point is treated as a pattern for pathname ex-
	      pansion, with an asterisk	implicitly appended.  This pattern  is
	      used to generate a list of matching file names for possible com-
	      pletions.
       glob-expand-word	(C-x *)
	      The word before point is treated as a pattern for	 pathname  ex-
	      pansion,	and  the  list of matching file	names is inserted, re-
	      placing the word.	 If a numeric argument is supplied, an	aster-
	      isk is appended before pathname expansion.
       glob-list-expansions (C-x g)
	      The  list	 of  expansions	 that  would  have  been  generated by
	      glob-expand-word is displayed, and the line is  redrawn.	 If  a
	      numeric  argument	 is  supplied,	an asterisk is appended	before
	      pathname expansion.
       dump-functions
	      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
	      inputrc file.
       dump-variables
	      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 inputrc file.
       dump-macros
	      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
	      inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about	the current instance of	bash.

   Programmable	Completion
       When  word  completion  is  attempted  for an argument to a command for
       which a completion specification	(a compspec) has  been	defined	 using
       the  complete  builtin (see SHELL BUILTIN COMMANDS below), the program-
       mable completion	facilities are invoked.

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

       Once  a	compspec  has  been  found, it is used to generate the list of
       matching	words.	If a compspec is not found, the	default	 bash  comple-
       tion as described above under Completing	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
       -f  or -d option	is used	for filename or	directory name completion, the
       shell variable FIGNORE is used to filter	the matches.

       Any completions specified by a pathname expansion pattern to the	-G op-
       tion  are  generated next.  The words generated by the pattern need not
       match the word being completed.	The GLOBIGNORE shell variable  is  not
       used to filter the matches, but the FIGNORE variable is used.

       Next,  the string specified as the argument to the -W option is consid-
       ered.  The string is first split	using the characters in	the  IFS  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 EXPANSION.	 The results are split using the rules
       described above under Word Splitting.  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 -F and -C options is invoked.	 When the  command  or
       function	is invoked, the	COMP_LINE, COMP_POINT, COMP_KEY, and COMP_TYPE
       variables are assigned values as	described above	under Shell Variables.
       If  a  shell  function  is being	invoked, the COMP_WORDS	and COMP_CWORD
       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 -F is invoked first.	 The function may  use
       any  of	the  shell facilities, including the compgen builtin described
       below, to generate the matches.	It must	put the	 possible  completions
       in the COMPREPLY	array variable.

       Next,  any  command specified with the -C 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 -X option is applied to the list.  The filter is	a pat-
       tern as used for	pathname expansion; a &	in  the	 pattern  is  replaced
       with  the text of the word being	completed.  A literal &	may be escaped
       with a backslash; the backslash is removed before attempting  a	match.
       Any  completion that matches the	pattern	will be	removed	from the list.
       A leading ! negates the pattern;	in this	case any completion not	match-
       ing the pattern will be removed.

       Finally,	any prefix and suffix specified	with the -P and	-S 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
       -o dirnames option was supplied to complete when	the compspec  was  de-
       fined, directory	name completion	is attempted.

       If  the	-o  plusdirs option was	supplied to complete 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 bash completions	are not	attempted, and the readline default of
       filename	completion is disabled.	 If the	-o bashdefault option was sup-
       plied  to complete when the compspec was	defined, the bash default com-
       pletions	are attempted if the compspec generates	no matches.  If	the -o
       default	option was supplied to complete	when the compspec was defined,
       readline's default completion will be performed if the  compspec	 (and,
       if attempted, the default bash 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	mark-directories readline variable, regardless of  the
       setting of the mark-symlinked-directories readline variable.

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

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

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

HISTORY
       When  the  -o  history  option to the set builtin is enabled, the shell
       provides	access to the command history, the list	of commands previously
       typed.	The  value  of	the HISTSIZE variable is used as the number of
       commands	to save	in a history list.  The	text of	the last HISTSIZE com-
       mands  (default	500)  is  saved.  The shell stores each	command	in the
       history list prior to parameter and variable expansion  (see  EXPANSION
       above)  but after history expansion is performed, subject to the	values
       of the shell variables HISTIGNORE and HISTCONTROL.

       On startup, the history is initialized from the file named by the vari-
       able  HISTFILE  (default	~/.bash_history).  The file named by the value
       of HISTFILE is truncated, if necessary, to contain  no  more  than  the
       number  of lines	specified by the value of HISTFILESIZE.	 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  de-
       pending	on the value of	the HISTTIMEFORMAT variable.  When an interac-
       tive shell exits, the last $HISTSIZE lines are copied from the  history
       list  to	$HISTFILE.  If the histappend shell option is enabled (see the
       description of shopt under SHELL	BUILTIN	COMMANDS below), the lines are
       appended	 to  the history file, otherwise the history file is overwrit-
       ten.  If	HISTFILE is unset, or if the history file is  unwritable,  the
       history	is  not	 saved.	  If  the HISTTIMEFORMAT 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 his-
       tory lines.  After saving the history, the history file is truncated to
       contain no more than HISTFILESIZE lines.	 If HISTFILESIZE is  not  set,
       no truncation is	performed.

       The  builtin  command fc	(see SHELL BUILTIN COMMANDS below) may be used
       to list or edit and re-execute a	portion	of the history list.  The his-
       tory  builtin may be used to display or modify the history list and ma-
       nipulate	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 HISTCONTROL and HISTIGNORE variables may be set to cause the
       shell to	save only a subset of the commands entered.  The cmdhist 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 lithist shell	option
       causes the shell	to save	the command with embedded newlines instead  of
       semicolons.  See	the description	of the shopt builtin below under SHELL
       BUILTIN COMMANDS	for information	on setting  and	 unsetting  shell  op-
       tions.

HISTORY	EXPANSION
       The  shell  supports a history expansion	feature	that is	similar	to the
       history expansion in csh.  This section describes what syntax  features
       are  available.	 This  feature	is  enabled by default for interactive
       shells, and can be disabled using the +H	option to the set builtin com-
       mand (see SHELL BUILTIN COMMANDS	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 event, and the portions of that line that	 are  acted  upon  are
       words.	Various	 modifiers  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 metacharacter-separated words surrounded by
       quotes are considered one word.	History	expansions are	introduced  by
       the  appearance	of  the	history	expansion character, which is !	by de-
       fault.  Only backslash (\) and single quotes can	quote the history  ex-
       pansion character.

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

       Several shell options settable with the shopt builtin may  be  used  to
       tailor  the behavior of history expansion.  If the histverify shell op-
       tion is enabled (see the	description of the shopt builtin  below),  and
       readline	 is  being  used,  history  substitutions  are not immediately
       passed to the shell parser.  Instead, the  expanded  line  is  reloaded
       into the	readline editing buffer	for further modification.  If readline
       is being	used, and the histreedit shell option  is  enabled,  a	failed
       history	substitution will be reloaded into the readline	editing	buffer
       for correction.	The -p option to the history builtin  command  may  be
       used  to	 see what a history expansion will do before using it.	The -s
       option to the history 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 histchars above under Shell
       Variables).  The	shell uses the history comment character to mark  his-
       tory timestamps when writing the	history	file.

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

       !      Start  a	history	substitution, except when followed by a	blank,
	      newline, carriage	return,	= or ( (when the extglob shell	option
	      is enabled using the shopt builtin).
       !n     Refer to command line n.
       !-n    Refer to the current command minus n.
       !!     Refer to the previous command.  This is a	synonym	for `!-1'.
       !string
	      Refer  to	the most recent	command	preceding the current position
	      in the history list starting with	string.
       !?string[?]
	      Refer to the most	recent command preceding the current postition
	      in  the  history	list containing	string.	 The trailing ?	may be
	      omitted if string	is followed immediately	by a newline.
       ^string1^string2^
	      Quick substitution.   Repeat  the	 previous  command,  replacing
	      string1  with  string2.  Equivalent to ``!!:s/string1/string2/''
	      (see Modifiers below).
       !#     The entire command line typed so far.

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

       0 (zero)
	      The zeroth word.	For the	shell, this is the command word.
       n      The nth word.
       ^      The first	argument.  That	is, word 1.
       $      The last argument.
       %      The word matched by the most recent `?string?' search.
       x-y    A	range of words;	`-y' abbreviates `0-y'.
       *      All  of  the words but the zeroth.  This is a synonym for	`1-$'.
	      It is not	an error to use	* if there is just  one	 word  in  the
	      event; the empty string is returned in that case.
       x*     Abbreviates x-$.
       x-     Abbreviates x-$ like x*, but omits the last word.

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

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

       h      Remove a trailing	file name component, leaving only the head.
       t      Remove all leading file name components, leaving the tail.
       r      Remove a trailing	suffix of the form .xxx, leaving the basename.
       e      Remove all but the trailing suffix.
       p      Print the	new command but	do not execute it.
       q      Quote the	substituted words, escaping further substitutions.
       x      Quote  the  substituted words as with q, but break into words at
	      blanks and newlines.
       s/old/new/
	      Substitute new for the first occurrence  of  old	in  the	 event
	      line.   Any  delimiter can be used in place of /.	 The final de-
	      limiter is optional if it	is the last  character	of  the	 event
	      line.   The delimiter may	be quoted in old and new with a	single
	      backslash.  If & appears in new, it is replaced by old.  A  sin-
	      gle  backslash  will  quote the &.  If old is null, it is	set to
	      the last old substituted,	or, if no previous  history  substitu-
	      tions took place,	the last string	in a !?string[?]  search.
       &      Repeat the previous substitution.
       g      Cause changes to be applied over the entire event	line.  This is
	      used in conjunction with `:s' (e.g.,  `:gs/old/new/')  or	 `:&'.
	      If  used with `:s', 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 may	be used	as a synonym for g.
       G      Apply  the following `s' modifier	once to	each word in the event
	      line.

SHELL BUILTIN COMMANDS
       Unless otherwise	noted, each builtin command documented in this section
       as accepting options preceded by	- accepts -- to	signify	the end	of the
       options.	 The :,	true, false, and test builtins do not  accept  options
       and do not treat	-- specially.  The exit, logout, break,	continue, let,
       and shift builtins accept and process arguments beginning with -	 with-
       out  requiring  --.   Other  builtins that accept arguments but are not
       specified as accepting options interpret	arguments beginning with -  as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
	      No  effect;  the command does nothing beyond expanding arguments
	      and performing any specified redirections.  A zero exit code  is
	      returned.

	.  filename [arguments]
       source filename [arguments]
	      Read and execute commands	from filename in the current shell en-
	      vironment	and return the exit status of the  last	 command  exe-
	      cuted from filename.  If filename	does not contain a slash, file
	      names in PATH are	used to	find the  directory  containing	 file-
	      name.   The  file	 searched  for in PATH need not	be executable.
	      When bash	is  not	 in  posix  mode,  the	current	 directory  is
	      searched	if no file is found in PATH.  If the sourcepath	option
	      to the shopt builtin command is turned  off,  the	 PATH  is  not
	      searched.	  If any arguments are supplied, they become the posi-
	      tional parameters	when filename is executed.  Otherwise the  po-
	      sitional	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 filename is not found or
	      cannot be	read.

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

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

       bind [-m	keymap]	[-lpsvPSV]
       bind [-m	keymap]	[-q function] [-u function] [-r	keyseq]
       bind [-m	keymap]	-f filename
       bind [-m	keymap]	-x keyseq:shell-command
       bind [-m	keymap]	keyseq:function-name
       bind readline-command
	      Display  current	readline key and function bindings, bind a key
	      sequence to a readline function or  macro,  or  set  a  readline
	      variable.	 Each non-option argument is a command as it would ap-
	      pear in .inputrc,	but each binding or command must be passed  as
	      a	separate argument; e.g., '"\C-x\C-r": re-read-init-file'.  Op-
	      tions, if	supplied, have the following meanings:
	      -m keymap
		     Use keymap	as the keymap to be affected by	the subsequent
		     bindings.	Acceptable keymap names	are emacs, emacs-stan-
		     dard, emacs-meta, emacs-ctlx,  vi,	 vi-move,  vi-command,
		     and  vi-insert.  vi is equivalent to vi-command; emacs is
		     equivalent	to emacs-standard.
	      -l     List the names of all readline functions.
	      -p     Display readline function names and bindings  in  such  a
		     way that they can be re-read.
	      -P     List current readline function names and bindings.
	      -s     Display  readline	key  sequences bound to	macros and the
		     strings they output in such a way that they  can  be  re-
		     read.
	      -S     Display  readline	key  sequences bound to	macros and the
		     strings they output.
	      -v     Display readline variable names and values	in such	a  way
		     that they can be re-read.
	      -V     List current readline variable names and values.
	      -f filename
		     Read key bindings from filename.
	      -q function
		     Query about which keys invoke the named function.
	      -u function
		     Unbind all	keys bound to the named	function.
	      -r keyseq
		     Remove any	current	binding	for keyseq.
	      -x keyseq:shell-command
		     Cause shell-command to be executed	whenever keyseq	is en-
		     tered.  When shell-command	is executed,  the  shell  sets
		     the  READLINE_LINE	 variable to the contents of the read-
		     line line buffer and the READLINE_POINT variable  to  the
		     current location of the insertion point.  If the executed
		     command changes  the  value  of  READLINE_LINE  or	 READ-
		     LINE_POINT,  those	 new  values  will be reflected	in the
		     editing state.

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

       break [n]
	      Exit  from  within a for,	while, until, or select	loop.  If n is
	      specified, break n levels.  n must be >= 1.   If	n  is  greater
	      than  the	number of enclosing loops, all enclosing loops are ex-
	      ited.  The return	value is non-zero when n is <=	0;  Otherwise,
	      break returns 0 value.

       builtin shell-builtin [arguments]
	      Execute  the  specified shell builtin, passing it	arguments, and
	      return its exit status.  This is useful when defining a function
	      whose  name  is the same as a shell builtin, retaining the func-
	      tionality	of the builtin within the function.  The cd builtin is
	      commonly	redefined  this	 way.	The  return status is false if
	      shell-builtin is not a shell builtin command.

       caller [expr]
	      Returns the context of any active	subroutine call	(a shell func-
	      tion or a	script executed	with the . or source builtins).	 With-
	      out expr,	caller displays	the line number	and source filename of
	      the  current subroutine call.  If	a non-negative integer is sup-
	      plied as expr, caller displays the line number, subroutine name,
	      and  source  file	 corresponding to that position	in the current
	      execution	call stack.  This extra	information may	be  used,  for
	      example,	to print a stack trace.	 The current frame is frame 0.
	      The return value is 0 unless the shell is	not executing  a  sub-
	      routine  call or expr does not correspond	to a valid position in
	      the call stack.

       cd [-L|[-P [-e]]] [dir]
	      Change the current directory to dir.  The	variable HOME  is  the
	      default  dir.   The  variable CDPATH defines the search path for
	      the directory containing dir.  Alternative  directory  names  in
	      CDPATH  are  separated by	a colon	(:).  A	null directory name in
	      CDPATH is	the same as the	current	directory,  i.e.,  ``.''.   If
	      dir begins with a	slash (/), then	CDPATH is not used. The	-P op-
	      tion says	to use the physical  directory	structure  instead  of
	      following	 symbolic  links  (see	also  the -P option to the set
	      builtin command);	the -L option forces symbolic links to be fol-
	      lowed.   If  the	-e option is supplied with -P, and the current
	      working directory	cannot be successfully determined after	a suc-
	      cessful directory	change,	cd will	return an unsuccessful status.
	      An argument of - is equivalent to	$OLDPWD.  If a	non-empty  di-
	      rectory name from	CDPATH is used,	or if -	is the first argument,
	      and the directory	change is successful, the absolute pathname of
	      the  new	working	 directory  is written to the standard output.
	      The return value is  true	 if  the  directory  was  successfully
	      changed; false otherwise.

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

       compgen [option]	[word]
	      Generate	possible  completion matches for word according	to the
	      options, which may  be  any  option  accepted  by	 the  complete
	      builtin  with  the exception of -p and -r, and write the matches
	      to the standard output.  When using the -F or  -C	 options,  the
	      various  shell  variables	set by the programmable	completion fa-
	      cilities,	while available, will not have useful values.

	      The matches will be generated in the same	way as if the program-
	      mable completion code had	generated them directly	from a comple-
	      tion specification with the same flags.  If word	is  specified,
	      only those completions matching word will	be displayed.

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

       complete	[-abcdefgjksuv]	[-o comp-option] [-DE] [-A action]  [-G	 glob-
       pat] [-W	wordlist] [-F function]	[-C command]
	      [-X filterpat] [-P prefix] [-S suffix] name [name	...]
       complete	-pr [-DE] [name	...]
	      Specify  how arguments to	each name should be completed.	If the
	      -p option	is supplied, or	if no options are  supplied,  existing
	      completion  specifications are printed in	a way that allows them
	      to be reused as input.  The -r option removes a completion spec-
	      ification	 for each name,	or, if no names	are supplied, all com-
	      pletion specifications.  The -D option indicates	that  the  re-
	      maining options and actions should apply to the ``default'' com-
	      mand completion; that is,	completion attempted on	a command  for
	      which  no	completion has previously been defined.	 The -E	option
	      indicates	that the remaining options and actions should apply to
	      ``empty''	command	completion; that is, completion	attempted on a
	      blank line.

	      The process of applying  these  completion  specifications  when
	      word  completion	is attempted is	described above	under Program-
	      mable Completion.

	      Other options, if	specified, have	the following  meanings.   The
	      arguments	 to the	-G, -W,	and -X options (and, if	necessary, the
	      -P and -S	options) should	be quoted to protect them from	expan-
	      sion before the complete builtin is invoked.
	      -o comp-option
		      The  comp-option	controls  several aspects of the comp-
		      spec's behavior beyond the simple	generation of  comple-
		      tions.  comp-option may be one of:
		      bashdefault
			      Perform the rest of the default bash completions
			      if the compspec generates	no matches.
		      default Use readline's default  filename	completion  if
			      the compspec generates no	matches.
		      dirnames
			      Perform  directory  name completion if the comp-
			      spec generates no	matches.
		      filenames
			      Tell readline that the compspec generates	 file-
			      names,  so  it can perform any filename-specific
			      processing (like adding  a  slash	 to  directory
			      names,  quoting special characters, or suppress-
			      ing trailing spaces).  Intended to be used  with
			      shell functions.
		      nospace Tell  readline  not  to  append a	space (the de-
			      fault) to	words completed	 at  the  end  of  the
			      line.
		      plusdirs
			      After  any  matches  defined by the compspec are
			      generated,  directory  name  completion  is  at-
			      tempted and any matches are added	to the results
			      of the other actions.
	      -A action
		      The action may be	one of the  following  to  generate  a
		      list of possible completions:
		      alias   Alias names.  May	also be	specified as -a.
		      arrayvar
			      Array variable names.
		      binding Readline key binding names.
		      builtin Names  of	 shell	builtin	commands.  May also be
			      specified	as -b.
		      command Command names.  May also be specified as -c.
		      directory
			      Directory	names.	May also be specified as -d.
		      disabled
			      Names of disabled	shell builtins.
		      enabled Names of enabled shell builtins.
		      export  Names of exported	shell variables.  May also  be
			      specified	as -e.
		      file    File names.  May also be specified as -f.
		      function
			      Names of shell functions.
		      group   Group names.  May	also be	specified as -g.
		      helptopic
			      Help topics as accepted by the help builtin.
		      hostname
			      Hostnames,  as  taken from the file specified by
			      the HOSTFILE shell variable.
		      job     Job names, if job	control	is active.   May  also
			      be specified as -j.
		      keyword Shell  reserved words.  May also be specified as
			      -k.
		      running Names of running jobs, if	job control is active.
		      service Service names.  May also be specified as -s.
		      setopt  Valid arguments for the -o  option  to  the  set
			      builtin.
		      shopt   Shell  option  names  as	accepted  by the shopt
			      builtin.
		      signal  Signal names.
		      stopped Names of stopped jobs, if	job control is active.
		      user    User names.  May also be specified as -u.
		      variable
			      Names of all shell variables.  May also be spec-
			      ified as -v.
	      -C command
		      command  is  executed in a subshell environment, and its
		      output is	used as	the possible completions.
	      -F function
		      The shell	function function is executed in  the  current
		      shell  environment.  When	it finishes, the possible com-
		      pletions are retrieved from the value of	the  COMPREPLY
		      array variable.
	      -G globpat
		      The  pathname  expansion	pattern	globpat	is expanded to
		      generate the possible completions.
	      -P prefix
		      prefix is	added at the beginning of each	possible  com-
		      pletion after all	other options have been	applied.
	      -S suffix
		      suffix is	appended to each possible completion after all
		      other options have been applied.
	      -W wordlist
		      The wordlist is split using the characters  in  the  IFS
		      special  variable	as delimiters, and each	resultant word
		      is expanded.  The	possible completions are  the  members
		      of  the  resultant  list which match the word being com-
		      pleted.
	      -X filterpat
		      filterpat	is a pattern as	used for  pathname  expansion.
		      It is applied to the list	of possible completions	gener-
		      ated by the preceding options and	 arguments,  and  each
		      completion  matching filterpat is	removed	from the list.
		      A	leading	! in filterpat negates the  pattern;  in  this
		      case, any	completion not matching	filterpat is removed.

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

       compopt [-o option] [-DE] [+o option] [name]
	      Modify  completion  options  for	each name according to the op-
	      tions, or	for the	currently-executing completion if no names are
	      supplied.	  If  no options are given, display the	completion op-
	      tions for	each name or the  current  completion.	 The  possible
	      values  of  option  are those valid for the complete builtin de-
	      scribed above.  The -D option indicates that the	remaining  op-
	      tions  should  apply to the ``default'' command completion; that
	      is, completion attempted on a command for	 which	no  completion
	      has  previously  been defined.  The -E option indicates that the
	      remaining	options	should apply to	``empty'' command  completion;
	      that is, completion attempted on a blank line.

	      The  return  value is true unless	an invalid option is supplied,
	      an attempt is made to modify the options for a name for which no
	      completion specification exists, or an output error occurs.

       continue	[n]
	      Resume the next iteration	of the enclosing for, while, until, or
	      select loop.  If n is specified, resume  at  the	nth  enclosing
	      loop.   n	 must be >= 1.	If n is	greater	than the number	of en-
	      closing loops, the last enclosing	loop (the ``top-level''	 loop)
	      is  resumed.   When continue is executed inside of loop, the re-
	      turn value is non-zero when n is <= 0; Otherwise,	 continue  re-
	      turns  0	value.	When continue is executed outside of loop, the
	      return value is 0.

       declare [-aAfFgilrtux] [-p] [name[=value] ...]
       typeset [-aAfFgilrtux] [-p] [name[=value] ...]
	      Declare variables	and/or give them attributes.  If no names  are
	      given  then display the values of	variables.  The	-p option will
	      display the attributes and values	of each	name.  When -p is used
	      with name	arguments, additional options are ignored.  When -p is
	      supplied without name arguments, it will display the  attributes
	      and  values  of all variables having the attributes specified by
	      the additional options.  If no other options are	supplied  with
	      -p,  declare will	display	the attributes and values of all shell
	      variables.  The -f option	will restrict  the  display  to	 shell
	      functions.  The -F option	inhibits the display of	function defi-
	      nitions; only the	function name and attributes are printed.   If
	      the  extdebug  shell  option  is enabled using shopt, the	source
	      file name	and line number	where the function is defined are dis-
	      played as	well.  The -F option implies -f.  The -g option	forces
	      variables	to be created or modified at the  global  scope,  even
	      when  declare is executed	in a shell function.  It is ignored in
	      all other	cases.	The following options can be used to  restrict
	      output  to  variables  with  the	specified attribute or to give
	      variables	attributes:
	      -a     Each name	is  an	indexed	 array	variable  (see	Arrays
		     above).
	      -A     Each  name	 is  an	associative array variable (see	Arrays
		     above).
	      -f     Use function names	only.
	      -i     The variable is treated as	an integer; arithmetic evalua-
		     tion  (see	ARITHMETIC EVALUATION above) is	performed when
		     the variable is assigned a	value.
	      -l     When the variable is assigned  a  value,  all  upper-case
		     characters	 are  converted	to lower-case.	The upper-case
		     attribute is disabled.
	      -r     Make names	readonly.  These names cannot then be assigned
		     values by subsequent assignment statements	or unset.
	      -t     Give each name the	trace attribute.  Traced functions in-
		     herit the DEBUG and RETURN	traps from the calling	shell.
		     The trace attribute has no	special	meaning	for variables.
	      -u     When  the	variable  is  assigned a value,	all lower-case
		     characters	are converted to upper-case.   The  lower-case
		     attribute is disabled.
	      -x     Mark  names for export to subsequent commands via the en-
		     vironment.

	      Using `+'	instead	of `-' turns off the attribute	instead,  with
	      the exceptions that +a may not be	used to	destroy	an array vari-
	      able and +r will not remove the readonly attribute.   When  used
	      in a function, makes each	name local, as with the	local command,
	      unless the -g option is supplied,	If a variable name is followed
	      by  =value,  the value of	the variable is	set to value.  The re-
	      turn value is 0 unless an	invalid	option is encountered, an  at-
	      tempt  is	made to	define a function using	``-f foo=bar'',	an at-
	      tempt is made to assign a	value to a readonly variable,  an  at-
	      tempt is made to assign a	value to an array variable without us-
	      ing the compound assignment syntax (see Arrays  above),  one  of
	      the names	is not a valid shell variable name, an attempt is made
	      to turn off readonly status for a	readonly variable, an  attempt
	      is  made	to  turn off array status for an array variable, or an
	      attempt is made to display a non-existent	function with -f.

       dirs [+n] [-n] [-clpv]
	      Without options, displays	the list of currently  remembered  di-
	      rectories.   The default display is on a single line with	direc-
	      tory names separated by spaces.  Directories are	added  to  the
	      list  with  the  pushd command; the popd command removes entries
	      from the list.
	      +n     Displays the nth entry counting from the left of the list
		     shown by dirs when	invoked	without	options, starting with
		     zero.
	      -n     Displays the nth entry counting from  the	right  of  the
		     list shown	by dirs	when invoked without options, starting
		     with zero.
	      -c     Clears the	directory stack	by deleting  all  of  the  en-
		     tries.
	      -l     Produces  a  longer  listing;  the	default	listing	format
		     uses a tilde to denote the	home directory.
	      -p     Print the directory stack with one	entry per line.
	      -v     Print the directory stack with one	entry per  line,  pre-
		     fixing each entry with its	index in the stack.

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

       disown [-ar] [-h] [jobspec ...]
	      Without options, each jobspec is removed from the	table  of  ac-
	      tive  jobs.  If jobspec is not present, and neither -a nor -r is
	      supplied,	the shell's notion of the current job is used.	If the
	      -h  option is given, each	jobspec	is not removed from the	table,
	      but is marked so that SIGHUP is not sent to the job if the shell
	      receives a SIGHUP.  If no	jobspec	is present, and	neither	the -a
	      nor the -r option	is supplied, the current job is	used.	If  no
	      jobspec  is  supplied, the -a option means to remove or mark all
	      jobs; the	-r option without a jobspec argument restricts	opera-
	      tion  to	running	 jobs.	The return value is 0 unless a jobspec
	      does not specify a valid job.

       echo [-neE] [arg	...]
	      Output the args, separated by spaces,  followed  by  a  newline.
	      The return status	is always 0.  If -n is specified, the trailing
	      newline is suppressed.  If the -e	option is  given,  interpreta-
	      tion  of	the following backslash-escaped	characters is enabled.
	      The -E option disables the interpretation	of these escape	 char-
	      acters,  even  on	systems	where they are interpreted by default.
	      The xpg_echo shell option	may be used to	dynamically  determine
	      whether  or not echo expands these escape	characters by default.
	      echo does	not interpret -- to mean the end of options.  echo in-
	      terprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress further output
	      \e
	      \E     an	escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal	tab
	      \v     vertical tab
	      \\     backslash
	      \0nnn  the  eight-bit  character	whose value is the octal value
		     nnn (zero to three	octal digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (one or two hex digits)
	      \uHHHH the  Unicode (ISO/IEC 10646) character whose value	is the
		     hexadecimal value HHHH (one to four hex digits)
	      \UHHHHHHHH
		     the Unicode (ISO/IEC 10646) character whose value is  the
		     hexadecimal value HHHHHHHH	(one to	eight hex digits)

       enable [-a] [-dnps] [-f filename] [name ...]
	      Enable  and disable builtin shell	commands.  Disabling a builtin
	      allows a disk command which has the same name as a shell builtin
	      to  be  executed without specifying a full pathname, even	though
	      the shell	normally searches for builtins before  disk  commands.
	      If  -n  is used, each name is disabled; otherwise, names are en-
	      abled.  For example, to use the test binary found	via  the  PATH
	      instead  of  the	shell builtin version, run ``enable -n test''.
	      The -f option means to load the new builtin  command  name  from
	      shared object filename, on systems that support dynamic loading.
	      The -d option will delete	a builtin previously loaded  with  -f.
	      If no name arguments are given, or if the	-p option is supplied,
	      a	list of	shell builtins is printed.  With no other option argu-
	      ments,  the  list	consists of all	enabled	shell builtins.	 If -n
	      is supplied, only	disabled builtins are printed.	If -a is  sup-
	      plied,  the  list	printed	includes all builtins, with an indica-
	      tion of whether or not each is enabled.  If -s is	supplied,  the
	      output  is restricted to the POSIX special builtins.  The	return
	      value is 0 unless	a name is not a	shell builtin or there	is  an
	      error loading a new builtin from a shared	object.

       eval [arg ...]
	      The  args	 are read and concatenated together into a single com-
	      mand.  This command is then read and executed by the shell,  and
	      its  exit	status is returned as the value	of eval.  If there are
	      no args, or only null arguments, eval returns 0.

       exec [-cl] [-a name] [command [arguments]]
	      If command is specified, it replaces the shell.  No new  process
	      is  created.  The	arguments become the arguments to command.  If
	      the -l option is supplied, the shell places a dash at the	begin-
	      ning of the zeroth argument passed to command.  This is what lo-
	      gin(1) does.  The	-c option causes command to be	executed  with
	      an  empty	environment.  If -a is supplied, the shell passes name
	      as the zeroth argument to	the executed command.  If command can-
	      not  be executed for some	reason,	a non-interactive shell	exits,
	      unless the shell option execfail is enabled, in  which  case  it
	      returns  failure.	  An  interactive shell	returns	failure	if the
	      file cannot be executed.	If command is not specified, any redi-
	      rections take effect in the current shell, and the return	status
	      is 0.  If	there is a redirection error, the return status	is 1.

       exit [n]
	      Cause the	shell to exit with a status of n.  If  n  is  omitted,
	      the exit status is that of the last command executed.  A trap on
	      EXIT is executed before the shell	terminates.

       export [-fn] [name[=word]] ...
       export -p
	      The supplied names are marked for	automatic export to the	 envi-
	      ronment  of subsequently executed	commands.  If the -f option is
	      given, the names refer to	functions.  If no names	are given,  or
	      if  the  -p option is supplied, a	list of	all names that are ex-
	      ported in	this shell is printed.	The -n option causes  the  ex-
	      port  property to	be removed from	each name.  If a variable name
	      is followed by =word, the	value of the variable is set to	 word.
	      export  returns  an exit status of 0 unless an invalid option is
	      encountered, one of the names is	not  a	valid  shell  variable
	      name, or -f is supplied with a name that is not a	function.

       fc [-e ename] [-lnr] [first] [last]
       fc -s [pat=rep] [cmd]
	      Fix  Command.  In	the first form,	a range	of commands from first
	      to last is selected from the history list.  First	and  last  may
	      be  specified  as	a string (to locate the	last command beginning
	      with that	string)	or as a	number	(an  index  into  the  history
	      list, where a negative number is used as an offset from the cur-
	      rent command number).  If	last is	not specified it is set	to the
	      current  command	for  listing (so that ``fc -l -10'' prints the
	      last 10 commands)	and to first otherwise.	 If first is not spec-
	      ified  it	is set to the previous command for editing and -16 for
	      listing.

	      The -n option suppresses the command numbers when	listing.   The
	      -r  option reverses the order of the commands.  If the -l	option
	      is given,	the commands are listed	on  standard  output.	Other-
	      wise,  the editor	given by ename is invoked on a file containing
	      those commands.  If ename	is not given, the value	of the	FCEDIT
	      variable	is used, and the value of EDITOR if FCEDIT is not set.
	      If neither variable is set, vi is	used.  When  editing  is  com-
	      plete, the edited	commands are echoed and	executed.

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

	      If  the  first form is used, the return value is 0 unless	an in-
	      valid option is encountered or first  or	last  specify  history
	      lines  out  of  range.  If the -e	option is supplied, the	return
	      value is the value of the	last command executed or failure if an
	      error occurs with	the temporary file of commands.	 If the	second
	      form is used, the	return status is that of the  command  re-exe-
	      cuted,  unless  cmd  does	 not  specify a	valid history line, in
	      which case fc returns failure.

       fg [jobspec]
	      Resume jobspec in	the foreground,	and make it the	 current  job.
	      If jobspec is not	present, the shell's notion of the current job
	      is used.	The return value is that of the	 command  placed  into
	      the  foreground,	or failure if run when job control is disabled
	      or, when run with	job control enabled, if	jobspec	does not spec-
	      ify  a  valid  job  or  jobspec specifies	a job that was started
	      without job control.

       getopts optstring name [args]
	      getopts is used by shell procedures to parse positional  parame-
	      ters.   optstring	 contains  the	option characters to be	recog-
	      nized; if	a character is followed	by a colon, the	option is  ex-
	      pected to	have an	argument, which	should be separated from it by
	      white space.  The	colon and question mark	characters may not  be
	      used  as	option	characters.   Each time	it is invoked, getopts
	      places the next option in	the shell variable name,  initializing
	      name if it does not exist, and the index of the next argument to
	      be processed into	the variable OPTIND.  OPTIND is	initialized to
	      1	each time the shell or a shell script is invoked.  When	an op-
	      tion requires an argument, getopts places	that argument into the
	      variable OPTARG.	The shell does not reset OPTIND	automatically;
	      it must be manually reset	 between  multiple  calls  to  getopts
	      within  the  same	shell invocation if a new set of parameters is
	      to be used.

	      When the end of options is encountered, getopts exits with a re-
	      turn value greater than zero.  OPTIND is set to the index	of the
	      first non-option argument, and name is set to ?.

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

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

	      If an invalid option is seen, getopts places ? into name and, if
	      not  silent,  prints  an	error  message	and unsets OPTARG.  If
	      getopts is silent, the option character found is placed  in  OP-
	      TARG and no diagnostic message is	printed.

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

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

       hash [-lr] [-p filename]	[-dt] [name]
	      Each time	hash is	invoked, the full pathname of the command name
	      is determined by searching the directories in $PATH  and	remem-
	      bered.  Any previously-remembered	pathname is discarded.	If the
	      -p option	is supplied, no	path search is performed, and filename
	      is  used	as  the	 full file name	of the command.	 The -r	option
	      causes the shell to forget all remembered	locations.  The	-d op-
	      tion  causes the shell to	forget the remembered location of each
	      name.  If	the -t option is supplied, the full pathname to	 which
	      each  name  corresponds  is printed.  If multiple	name arguments
	      are supplied with	-t, the	name is	printed	before the hashed full
	      pathname.	 The -l	option causes output to	be displayed in	a for-
	      mat that may be reused as	input.	If no arguments	are given,  or
	      if only -l is supplied, information about	remembered commands is
	      printed.	The return status is true unless a name	is  not	 found
	      or an invalid option is supplied.

       help [-dms] [pattern]
	      Display  helpful information about builtin commands.  If pattern
	      is specified, help gives detailed	help on	all commands  matching
	      pattern;	otherwise  help	for all	the builtins and shell control
	      structures is printed.
	      -d     Display a short description of each pattern
	      -m     Display the description of	each pattern in	a manpage-like
		     format
	      -s     Display only a short usage	synopsis for each pattern

	      The return status	is 0 unless no command matches pattern.

       history [n]
       history -c
       history -d offset
       history -anrw [filename]
       history -p arg [arg ...]
       history -s arg [arg ...]
	      With no options, display the command history list	with line num-
	      bers.  Lines listed with a * have	been modified.	An argument of
	      n	 lists only the	last n lines.  If the shell variable HISTTIME-
	      FORMAT is	set and	not null, it is	used as	a  format  string  for
	      strftime(3)  to display the time stamp associated	with each dis-
	      played history entry.  No	intervening blank is  printed  between
	      the  formatted  time stamp and the history line.	If filename is
	      supplied,	it is used as the name of the history  file;  if  not,
	      the  value  of HISTFILE is used.	Options, if supplied, have the
	      following	meanings:
	      -c     Clear the history list by deleting	all the	entries.
	      -d offset
		     Delete the	history	entry at position offset.
	      -a     Append the	``new''	history	lines (history	lines  entered
		     since  the	 beginning of the current bash session)	to the
		     history file.
	      -n     Read the history lines not	already	read from the  history
		     file  into	the current history list.  These are lines ap-
		     pended to the history file	since  the  beginning  of  the
		     current bash session.
	      -r     Read the contents of the history file and use them	as the
		     current history.
	      -w     Write the current history to the history file,  overwrit-
		     ing the history file's contents.
	      -p     Perform  history  substitution  on	the following args and
		     display the result	on  the	 standard  output.   Does  not
		     store  the	results	in the history list.  Each arg must be
		     quoted to disable normal history expansion.
	      -s     Store the args in the history list	 as  a	single	entry.
		     The  last	command	 in the	history	list is	removed	before
		     the args are added.

	      If the HISTTIMEFORMAT variable is	set, the time  stamp  informa-
	      tion  associated	with each history entry	is written to the his-
	      tory file, marked	with the history comment character.  When  the
	      history  file  is	read, lines beginning with the history comment
	      character	followed immediately by	a  digit  are  interpreted  as
	      timestamps for the previous history line.	 The return value is 0
	      unless an	invalid	option is encountered, an error	 occurs	 while
	      reading  or  writing the history file, an	invalid	offset is sup-
	      plied as an argument to -d, or the history expansion supplied as
	      an argument to -p	fails.

       jobs [-lnprs] [ jobspec ... ]
       jobs -x command [ args ... ]
	      The first	form lists the active jobs.  The options have the fol-
	      lowing meanings:
	      -l     List process IDs in addition to the normal	information.
	      -n     Display information only about  jobs  that	 have  changed
		     status since the user was last notified of	their status.
	      -p     List  only	 the  process  ID  of  the job's process group
		     leader.
	      -r     Restrict output to	running	jobs.
	      -s     Restrict output to	stopped	jobs.

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

	      If the -x	option is supplied, jobs replaces any jobspec found in
	      command or args with the corresponding process group ID, and ex-
	      ecutes command passing it	args, returning	its exit status.

       kill [-s	sigspec	| -n signum | -sigspec]	[pid | jobspec]	...
       kill -l [sigspec	| exit_status]
	      Send the signal named by sigspec	or  signum  to	the  processes
	      named  by	 pid or	jobspec.  sigspec is either a case-insensitive
	      signal name such as SIGKILL (with	or without the SIG prefix)  or
	      a	 signal	 number; signum	is a signal number.  If	sigspec	is not
	      present, then SIGTERM is assumed.	 An argument of	-l  lists  the
	      signal  names.   If any arguments	are supplied when -l is	given,
	      the names	of the signals	corresponding  to  the	arguments  are
	      listed, and the return status is 0.  The exit_status argument to
	      -l is a number specifying	either a signal	 number	 or  the  exit
	      status  of  a process terminated by a signal.  kill returns true
	      if at least one signal was successfully sent, or false if	an er-
	      ror occurs or an invalid option is encountered.

       let arg [arg ...]
	      Each arg is an arithmetic	expression to be evaluated (see	ARITH-
	      METIC EVALUATION above).	If the last arg	evaluates  to  0,  let
	      returns 1; 0 is returned otherwise.

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

       logout Exit a login shell.

       mapfile	[-n  count]  [-O origin] [-s count] [-t] [-u fd] [-C callback]
       [-c quantum] [array]
       readarray [-n count] [-O	origin]	[-s count] [-t]	[-u fd]	[-C  callback]
       [-c quantum] [array]
	      Read  lines from the standard input into the indexed array vari-
	      able array, or from file descriptor fd if	the -u option is  sup-
	      plied.   The variable MAPFILE is the default array.  Options, if
	      supplied,	have the following meanings:
	      -n     Copy at most count	lines.	If count is 0, all  lines  are
		     copied.
	      -O     Begin  assigning  to  array at index origin.  The default
		     index is 0.
	      -s     Discard the first count lines read.
	      -t     Remove a trailing newline from each line read.
	      -u     Read lines	from file descriptor fd	instead	of  the	 stan-
		     dard input.
	      -C     Evaluate  callback	each time quantum lines	are read.  The
		     -c	option specifies quantum.
	      -c     Specify the number	of lines read  between	each  call  to
		     callback.

	      If  -C  is  specified  without  -c, the default quantum is 5000.
	      When callback is evaluated, it is	supplied the index of the next
	      array element to be assigned and the line	to be assigned to that
	      element as additional arguments.	callback  is  evaluated	 after
	      the line is read but before the array element is assigned.

	      If  not supplied with an explicit	origin,	mapfile	will clear ar-
	      ray before assigning to it.

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

       popd [-n] [+n] [-n]
	      Removes entries from the directory stack.	  With	no  arguments,
	      removes  the  top	directory from the stack, and performs a cd to
	      the new top directory.  Arguments, if supplied, have the follow-
	      ing meanings:
	      -n     Suppresses	 the  normal change of directory when removing
		     directories from the stack, so that only the stack	is ma-
		     nipulated.
	      +n     Removes  the nth entry counting from the left of the list
		     shown by dirs, starting with zero.	 For  example:	``popd
		     +0'' removes the first directory, ``popd +1'' the second.
	      -n     Removes the nth entry counting from the right of the list
		     shown by dirs, starting with zero.	 For  example:	``popd
		     -0''  removes the last directory, ``popd -1'' the next to
		     last.

	      If the popd command is successful, a dirs	is performed as	 well,
	      and  the	return	status is 0.  popd returns false if an invalid
	      option is	encountered, the directory stack is empty, a non-exis-
	      tent directory stack entry is specified, or the directory	change
	      fails.

       printf [-v var] format [arguments]
	      Write the	formatted arguments to the standard output  under  the
	      control  of  the	format.	 The -v	option causes the output to be
	      assigned to the variable var rather than being  printed  to  the
	      standard output.

	      The  format  is a	character string which contains	three types of
	      objects: plain characters, which are simply copied  to  standard
	      output,  character  escape  sequences,  which  are converted and
	      copied to	the standard output, and format	 specifications,  each
	      of  which	 causes	 printing of the next successive argument.  In
	      addition to the standard printf(1) format	specifications,	printf
	      interprets the following extensions:
	      %b     causes printf to expand backslash escape sequences	in the
		     corresponding argument (except that \c terminates output,
		     backslashes  in \', \", and \? are	not removed, and octal
		     escapes beginning with \0 may contain up to four digits).
	      %q     causes printf to output the corresponding argument	 in  a
		     format that can be	reused as shell	input.
	      %(datefmt)T
		     causes  printf  to	 output	the date-time string resulting
		     from using	datefmt	as a format  string  for  strftime(3).
		     The corresponding argument	is an integer representing the
		     number of seconds since the epoch.	 Two special  argument
		     values  may  be used: -1 represents the current time, and
		     -2	represents the time the	shell was invoked.

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

	      The  format  is  reused as necessary to consume all of the argu-
	      ments.  If the format requires more arguments than are supplied,
	      the  extra  format  specifications  behave as if a zero value or
	      null string, as appropriate,  had	 been  supplied.   The	return
	      value is zero on success,	non-zero on failure.

       pushd [-n] [+n] [-n]
       pushd [-n] [dir]
	      Adds  a  directory to the	top of the directory stack, or rotates
	      the stack, making	the new	top of the stack the  current  working
	      directory.  With no arguments, exchanges the top two directories
	      and returns 0, unless the	directory stack	is empty.   Arguments,
	      if supplied, have	the following meanings:
	      -n     Suppresses	the normal change of directory when adding di-
		     rectories to the stack, so	that only the stack is manipu-
		     lated.
	      +n     Rotates  the  stack  so  that the nth directory (counting
		     from the left of the list shown by	 dirs,	starting  with
		     zero) is at the top.
	      -n     Rotates  the  stack  so  that the nth directory (counting
		     from the right of the list	shown by dirs,	starting  with
		     zero) is at the top.
	      dir    Adds dir to the directory stack at	the top, making	it the
		     new current working directory.

	      If the pushd command is successful, a dirs is performed as well.
	      If  the first form is used, pushd	returns	0 unless the cd	to dir
	      fails.  With the second form, pushd returns 0 unless the	direc-
	      tory  stack  is empty, a non-existent directory stack element is
	      specified, or the	directory change to the	specified new  current
	      directory	fails.

       pwd [-LP]
	      Print  the  absolute  pathname of	the current working directory.
	      The pathname printed contains no symbolic	links if the -P	option
	      is supplied or the -o physical option to the set builtin command
	      is enabled.  If the -L option is used, the pathname printed  may
	      contain  symbolic	links.	The return status is 0 unless an error
	      occurs while reading the name of the current directory or	an in-
	      valid option is supplied.

       read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p
       prompt] [-t timeout] [-u	fd] [name ...]
	      One line is read from the	standard input,	or from	the  file  de-
	      scriptor	fd  supplied  as an argument to	the -u option, and the
	      first word is assigned to	the first name,	the second word	to the
	      second  name, and	so on, with leftover words and their interven-
	      ing separators assigned to the last name.	 If  there  are	 fewer
	      words read from the input	stream than names, the remaining names
	      are assigned empty values.  The characters in IFS	 are  used  to
	      split  the  line into words.  The	backslash character (\)	may be
	      used to remove any special meaning for the next  character  read
	      and  for line continuation.  Options, if supplied, have the fol-
	      lowing meanings:
	      -a aname
		     The words are assigned to sequential indices of the array
		     variable aname, starting at 0.  aname is unset before any
		     new values	are assigned.  Other name  arguments  are  ig-
		     nored.
	      -d delim
		     The first character of delim is used to terminate the in-
		     put line, rather than newline.
	      -e     If	the standard input is coming from a terminal, readline
		     (see  READLINE  above) is used to obtain the line.	 Read-
		     line uses the current (or default,	if  line  editing  was
		     not previously active) editing settings.
	      -i text
		     If	 readline  is  being  used  to	read the line, text is
		     placed into the editing buffer before editing begins.
	      -n nchars
		     read returns after	reading	nchars characters rather  than
		     waiting  for a complete line of input, but	honor a	delim-
		     iter if fewer than	nchars characters are read before  the
		     delimiter.
	      -N nchars
		     read  returns  after  reading  exactly  nchars characters
		     rather than waiting for a complete	line of	input,	unless
		     EOF  is encountered or read times out.  Delimiter charac-
		     ters encountered in the input are not  treated  specially
		     and  do  not cause	read to	return until nchars characters
		     are read.
	      -p prompt
		     Display prompt on standard	error, without a trailing new-
		     line, before attempting to	read any input.	 The prompt is
		     displayed only if input is	coming from a terminal.
	      -r     Backslash does not	act as an escape character.  The back-
		     slash  is considered to be	part of	the line.  In particu-
		     lar, a backslash-newline pair may not be used as  a  line
		     continuation.
	      -s     Silent mode.  If input is coming from a terminal, charac-
		     ters are not echoed.
	      -t timeout
		     Cause read	to time	out and	return failure if  a  complete
		     line  of input is not read	within timeout seconds.	 time-
		     out may be	a decimal number  with	a  fractional  portion
		     following	the decimal point.  This option	is only	effec-
		     tive if read is reading input from	a terminal,  pipe,  or
		     other  special  file;  it has no effect when reading from
		     regular files.  If	timeout	is 0, read 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.
	      -u fd  Read input	from file descriptor fd.

	      If no names are supplied,	the line read is assigned to the vari-
	      able REPLY.  The return code is zero, unless end-of-file is  en-
	      countered,  read	times  out  (in	 which case the	return code is
	      greater than 128), or an invalid file descriptor is supplied  as
	      the argument to -u.

       readonly	[-aAf] [-p] [name[=word] ...]
	      The  given  names	are marked readonly; the values	of these names
	      may not be changed by subsequent assignment.  If the  -f	option
	      is  supplied,  the  functions  corresponding to the names	are so
	      marked.  The -a option restricts the variables  to  indexed  ar-
	      rays;  the  -A option restricts the variables to associative ar-
	      rays.  If	both options are supplied, -A takes precedence.	 If no
	      name  arguments  are  given,  or if the -p option	is supplied, a
	      list of all readonly names is printed.  The other	options	may be
	      used  to	restrict the output to a subset	of the set of readonly
	      names.  The -p option causes output to be	displayed in a	format
	      that  may	be reused as input.  If	a variable name	is followed by
	      =word, the value of the variable is set  to  word.   The	return
	      status  is 0 unless an invalid option is encountered, one	of the
	      names is not a valid shell variable name,	or -f is supplied with
	      a	name that is not a function.

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

       set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]
       set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg	...]
	      Without options, the name	and value of each shell	 variable  are
	      displayed	in a format that can be	reused as input	for setting or
	      resetting	the currently-set variables.  Read-only	variables can-
	      not  be  reset.  In posix	mode, only shell variables are listed.
	      The output is sorted according to	the current locale.  When  op-
	      tions  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
	      $1, $2, ...  $n.	Options,  if  specified,  have	the  following
	      meanings:
	      -a      Automatically  mark  variables  and  functions which are
		      modified or created for export  to  the  environment  of
		      subsequent commands.
	      -b      Report  the status of terminated background jobs immedi-
		      ately, rather than before	the next primary prompt.  This
		      is effective only	when job control is enabled.
	      -e      Exit  immediately	 if a pipeline (which may consist of a
		      single simple command),  a subshell command enclosed  in
		      parentheses,  or one of the commands executed as part of
		      a	command	list enclosed by  braces  (see	SHELL  GRAMMAR
		      above) exits with	a non-zero status.  The	shell does not
		      exit if the command that fails is	part  of  the  command
		      list  immediately	 following  a  while or	until keyword,
		      part of the test	following  the	if  or	elif  reserved
		      words,  part  of any command executed in a && or || list
		      except the command following the final  &&  or  ||,  any
		      command  in a pipeline but the last, or if the command's
		      return value is being inverted with !.  A	trap  on  ERR,
		      if set, is executed before the shell exits.  This	option
		      applies to the shell environment and each	subshell envi-
		      ronment  separately  (see	 COMMAND EXECUTION ENVIRONMENT
		      above), and may cause subshells to exit before executing
		      all the commands in the subshell.
	      -f      Disable pathname expansion.
	      -h      Remember	the location of	commands as they are looked up
		      for execution.  This is enabled by default.
	      -k      All arguments in the form	of assignment  statements  are
		      placed  in the environment for a command,	not just those
		      that precede the command name.
	      -m      Monitor mode.  Job control is enabled.  This  option  is
		      on  by  default  for  interactive	shells on systems that
		      support it (see JOB  CONTROL  above).   Background  pro-
		      cesses  run  in a	separate process group and a line con-
		      taining their exit status	is printed upon	their  comple-
		      tion.
	      -n      Read commands but	do not execute them.  This may be used
		      to check a shell script for syntax errors.  This is  ig-
		      nored by interactive shells.
	      -o option-name
		      The option-name can be one of the	following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use  an  emacs-style command line	editing	inter-
			      face.  This is enabled by	default	when the shell
			      is interactive, unless the shell is started with
			      the --noediting option.  This also  affects  the
			      editing interface	used for read -e.
		      errexit Same as -e.
		      errtrace
			      Same as -E.
		      functrace
			      Same as -T.
		      hashall Same as -h.
		      histexpand
			      Same as -H.
		      history Enable command history, as described above under
			      HISTORY.	This option is on by default in	inter-
			      active shells.
		      ignoreeof
			      The  effect  is  as  if  the shell command ``IG-
			      NOREEOF=10'' had been executed (see Shell	 Vari-
			      ables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.
		      nolog   Currently	ignored.
		      notify  Same as -b.
		      nounset Same as -u.
		      onecmd  Same as -t.
		      physical
			      Same as -P.
		      pipefail
			      If  set,	the  return value of a pipeline	is the
			      value of the last	(rightmost)  command  to  exit
			      with  a non-zero status, or zero if all commands
			      in the pipeline exit successfully.  This	option
			      is disabled by default.
		      posix   Change  the  behavior  of	bash where the default
			      operation	differs	from  the  POSIX  standard  to
			      match the	standard (posix	mode).
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      vi      Use  a  vi-style command line editing interface.
			      This also	affects	the editing interface used for
			      read -e.
		      xtrace  Same as -x.
		      If -o is supplied	with no	option-name, the values	of the
		      current options are printed.  If +o is supplied with  no
		      option-name,  a  series  of set commands to recreate the
		      current option settings is  displayed  on	 the  standard
		      output.
	      -p      Turn  on	privileged  mode.   In this mode, the $ENV and
		      $BASH_ENV	files are not processed, shell	functions  are
		      not  inherited  from the environment, and	the SHELLOPTS,
		      BASHOPTS,	CDPATH,	and GLOBIGNORE variables, if they  ap-
		      pear  in	the environment, are ignored.  If the shell is
		      started with the effective user (group) id not equal  to
		      the  real	user (group) id, and the -p option is not sup-
		      plied, these actions are taken and the effective user id
		      is  set  to  the real user id.  If the -p	option is sup-
		      plied at startup,	the effective user id  is  not	reset.
		      Turning  this  option  off causes	the effective user and
		      group ids	to be set to the real user and group ids.
	      -t      Exit after reading and executing one command.
	      -u      Treat unset variables and	parameters other than the spe-
		      cial  parameters "@" and "*" as an error when performing
		      parameter	expansion.  If expansion is  attempted	on  an
		      unset  variable  or parameter, the shell prints an error
		      message, and, if not interactive,	exits with a  non-zero
		      status.
	      -v      Print shell input	lines as they are read.
	      -x      After  expanding	each simple command, for command, case
		      command, select command, or arithmetic for command, dis-
		      play  the	expanded value of PS4, followed	by the command
		      and its expanded arguments or associated word list.
	      -B      The shell	performs brace expansion (see Brace  Expansion
		      above).  This is on by default.
	      -C      If  set,	bash  does not overwrite an existing file with
		      the >, >&, and <>	redirection operators.	 This  may  be
		      overridden when creating output files by using the redi-
		      rection operator >| instead of >.
	      -E      If set, any trap on ERR is inherited by shell functions,
		      command  substitutions,  and commands executed in	a sub-
		      shell environment.  The ERR trap is normally not	inher-
		      ited in such cases.
	      -H      Enable !	style history substitution.  This option is on
		      by default when the shell	is interactive.
	      -P      If set, the shell	does not follow	 symbolic  links  when
		      executing	 commands  such	 as cd that change the current
		      working  directory.   It	uses  the  physical  directory
		      structure	instead.  By default, bash follows the logical
		      chain of	directories  when  performing  commands	 which
		      change the current directory.
	      -T      If  set,	any traps on DEBUG and RETURN are inherited by
		      shell functions, command substitutions, and commands ex-
		      ecuted  in a subshell environment.  The DEBUG and	RETURN
		      traps are	normally not inherited in such cases.
	      --      If no arguments follow this option, then the  positional
		      parameters are unset.  Otherwise,	the positional parame-
		      ters are set to the args,	even if	 some  of  them	 begin
		      with a -.
	      -	      Signal  the  end of options, cause all remaining args to
		      be assigned to the positional parameters.	 The -x	and -v
		      options are turned off.  If there	are no args, the posi-
		      tional parameters	remain unchanged.

	      The options are off by default unless otherwise noted.  Using  +
	      rather  than  -  causes these options to be turned off.  The op-
	      tions can	also be	specified as arguments to an invocation	of the
	      shell.   The current set of options may be found in $-.  The re-
	      turn status is always true unless	an invalid option  is  encoun-
	      tered.

       shift [n]
	      The  positional  parameters  from	n+1 ...	are renamed to $1 ....
	      Parameters represented by	the numbers $# down to $#-n+1 are  un-
	      set.   n must be a non-negative number less than or equal	to $#.
	      If n is 0, no parameters are changed.  If	n is not given,	it  is
	      assumed to be 1.	If n is	greater	than $#, the positional	param-
	      eters are	not changed.  The return status	is greater  than  zero
	      if n is greater than $# or less than zero; otherwise 0.

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

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

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

	      The list of shopt	options	is:

	      autocd  If  set,	a command name that is the name	of a directory
		      is executed as if	it were	the argument to	 the  cd  com-
		      mand.  This option is only used by interactive shells.
	      cdable_vars
		      If  set,	an  argument to	the cd builtin command that is
		      not a directory is assumed to be the name	of a  variable
		      whose value is the directory to change to.
	      cdspell If set, minor errors in the spelling of a	directory com-
		      ponent in	a cd command will be  corrected.   The	errors
		      checked for are transposed characters, a missing charac-
		      ter, and one character too many.	 If  a	correction  is
		      found,  the corrected file name is printed, and the com-
		      mand proceeds.  This option is only used by  interactive
		      shells.
	      checkhash
		      If set, bash checks that a command found in the hash ta-
		      ble exists before	trying to execute  it.	 If  a	hashed
		      command  no  longer exists, a normal path	search is per-
		      formed.
	      checkjobs
		      If set, bash lists the status of any stopped and running
		      jobs  before  exiting an interactive shell.  If any jobs
		      are running, this	causes the exit	to be deferred until a
		      second  exit is attempted	without	an intervening command
		      (see JOB CONTROL above).	The shell always postpones ex-
		      iting if any jobs	are stopped.
	      checkwinsize
		      If  set,	bash checks the	window size after each command
		      and, if necessary, updates the values of LINES and  COL-
		      UMNS.
	      cmdhist If  set,	bash attempts to save all lines	of a multiple-
		      line command in the same	history	 entry.	  This	allows
		      easy re-editing of multi-line commands.
	      compat31
		      If set, bash changes its behavior	to that	of version 3.1
		      with respect to quoted arguments to the  [[  conditional
		      command's	=~ operator.
	      compat32
		      If set, bash changes its behavior	to that	of version 3.2
		      with respect to locale-specific string  comparison  when
		      using  the  [[  conditional command's < and > operators.
		      Bash versions prior to bash-4.1 use ASCII	collation  and
		      strcmp(3);  bash-4.1  and	later use the current locale's
		      collation	sequence and strcoll(3).
	      compat40
		      If set, bash changes its behavior	to that	of version 4.0
		      with  respect  to	locale-specific	string comparison when
		      using the	[[ conditional command's  <  and  >  operators
		      (see  previous  item)  and  the effect of	interrupting a
		      command list.
	      compat41
		      If set, bash, when in posix mode,	treats a single	 quote
		      in  a  double-quoted  parameter  expansion  as a special
		      character.  The single quotes must match (an  even  num-
		      ber)  and	 the  characters between the single quotes are
		      considered quoted.  This is the behavior of  posix  mode
		      through  version 4.1.  The default bash behavior remains
		      as in previous versions.
	      direxpand
		      If set, bash replaces directory names with  the  results
		      of  word	expansion when performing filename completion.
		      This changes the contents	of the readline	 editing  buf-
		      fer.   If	 not  set,  bash attempts to preserve what the
		      user typed.
	      dirspell
		      If set, bash attempts spelling correction	 on  directory
		      names  during word completion if the directory name ini-
		      tially supplied does not exist.
	      dotglob If set, bash includes filenames beginning	with a `.'  in
		      the results of pathname expansion.
	      execfail
		      If set, a	non-interactive	shell will not exit if it can-
		      not execute the file specified as	 an  argument  to  the
		      exec  builtin  command.	An  interactive	shell does not
		      exit if exec fails.
	      expand_aliases
		      If set, aliases are expanded as  described  above	 under
		      ALIASES.	This option is enabled by default for interac-
		      tive shells.
	      extdebug
		      If set, behavior intended	for use	by  debuggers  is  en-
		      abled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name	supplied as an argument.
		      2.     If	 the  command  run by the DEBUG	trap returns a
			     non-zero value, the next command is  skipped  and
			     not executed.
		      3.     If	 the  command  run by the DEBUG	trap returns a
			     value of 2, and the shell is executing in a  sub-
			     routine  (a shell function	or a shell script exe-
			     cuted by the . or source builtins), a call	to re-
			     turn is simulated.
		      4.     BASH_ARGC	and BASH_ARGV are updated as described
			     in	their descriptions above.
		      5.     Function tracing is enabled:   command  substitu-
			     tion, shell functions, and	subshells invoked with
			     ( command ) inherit the DEBUG and RETURN traps.
		      6.     Error tracing is enabled:	command	 substitution,
			     shell  functions,	and  subshells	invoked	with (
			     command ) inherit the ERR trap.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      extquote
		      If  set,	$'string'  and	$"string" quoting is performed
		      within  ${parameter}  expansions	enclosed   in	double
		      quotes.  This option is enabled by default.
	      failglob
		      If  set,	patterns  which	fail to	match filenames	during
		      pathname expansion result	in an expansion	error.
	      force_fignore
		      If set, the suffixes  specified  by  the	FIGNORE	 shell
		      variable	cause words to be ignored when performing word
		      completion even if the ignored words are the only	possi-
		      ble  completions.	  See  SHELL VARIABLES above for a de-
		      scription	of FIGNORE.  This option  is  enabled  by  de-
		      fault.
	      globstar
		      If set, the pattern ** used in a pathname	expansion con-
		      text will	match all files	and zero or  more  directories
		      and  subdirectories.  If the pattern is followed by a /,
		      only directories and subdirectories match.
	      gnu_errfmt
		      If set, shell error messages are written in the standard
		      GNU error	message	format.
	      histappend
		      If  set,	the history list is appended to	the file named
		      by the value of the HISTFILE variable when the shell ex-
		      its, rather than overwriting the file.
	      histreedit
		      If  set, and readline is being used, a user is given the
		      opportunity to re-edit a failed history substitution.
	      histverify
		      If set, and readline is being used, the results of  his-
		      tory  substitution  are  not  immediately	 passed	to the
		      shell parser.  Instead, the  resulting  line  is	loaded
		      into the readline	editing	buffer,	allowing further modi-
		      fication.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to
		      perform  hostname	 completion when a word	containing a @
		      is  being	 completed  (see  Completing  under   READLINE
		      above).  This is enabled by default.
	      huponexit
		      If set, bash will	send SIGHUP to all jobs	when an	inter-
		      active login shell exits.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word
		      and  all remaining characters on that line to be ignored
		      in an interactive	shell (see COMMENTS above).  This  op-
		      tion is enabled by default.
	      lastpipe
		      If  set,	and  job control is not	active,	the shell runs
		      the last command of a pipeline not executed in the back-
		      ground in	the current shell environment.
	      lithist If  set,	and  the cmdhist option	is enabled, multi-line
		      commands are saved to the	history	with embedded newlines
		      rather than using	semicolon separators where possible.
	      login_shell
		      The  shell  sets this option if it is started as a login
		      shell (see INVOCATION above).   The  value  may  not  be
		      changed.
	      mailwarn
		      If  set,	and  a file that bash is checking for mail has
		      been accessed since the last time	it  was	 checked,  the
		      message  ``The  mail in mailfile has been	read'' is dis-
		      played.
	      no_empty_cmd_completion
		      If set, and readline is being used, bash	will  not  at-
		      tempt  to	 search	the PATH for possible completions when
		      completion is attempted on an empty line.
	      nocaseglob
		      If set, bash matches  filenames  in  a  case-insensitive
		      fashion when performing pathname expansion (see Pathname
		      Expansion	above).
	      nocasematch
		      If set, bash  matches  patterns  in  a  case-insensitive
		      fashion when performing matching while executing case or
		      [[ conditional commands.
	      nullglob
		      If set, bash allows patterns which match no  files  (see
		      Pathname	Expansion  above)  to expand to	a null string,
		      rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Pro-
		      grammable	Completion above) are enabled.	This option is
		      enabled by default.
	      promptvars
		      If set, prompt strings undergo parameter expansion, com-
		      mand  substitution,  arithmetic expansion, and quote re-
		      moval after being	expanded  as  described	 in  PROMPTING
		      above.  This option is enabled by	default.
	      restricted_shell
		      The  shell  sets	this  option  if  it is	started	in re-
		      stricted mode (see RESTRICTED SHELL below).   The	 value
		      may  not be changed.  This is not	reset when the startup
		      files are	executed, allowing the startup files  to  dis-
		      cover whether or not a shell is restricted.
	      shift_verbose
		      If  set,	the shift builtin prints an error message when
		      the shift	count exceeds the number of positional parame-
		      ters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to
		      find the directory containing the	file  supplied	as  an
		      argument.	 This option is	enabled	by default.
	      xpg_echo
		      If  set,	the  echo builtin expands backslash-escape se-
		      quences by default.

       suspend [-f]
	      Suspend the execution of this shell until	it receives a  SIGCONT
	      signal. When the suspended shell is a background process,	it can
	      be restarted by the fg command. For more information,  read  the
	      JOB CONTROL section. The suspend command can not suspend the lo-
	      gin shell. However, when -f option is specified, suspend command
	      can suspend even login shell.  The return	status is 0 unless the
	      shell is a login shell and -f is not supplied, or	if job control
	      is not enabled.

       test expr
       [ expr ]
	      Return  a	 status	 of  0 or 1 depending on the evaluation	of the
	      conditional expression expr.  Each operator and operand must  be
	      a	 separate argument.  Expressions are composed of the primaries
	      described	above under CONDITIONAL	EXPRESSIONS.   test  does  not
	      accept any options, nor does it accept and ignore	an argument of
	      -- as signifying the end of options.

	      Expressions may  be  combined  using  the	 following  operators,
	      listed  in  decreasing  order of precedence.  The	evaluation de-
	      pends on the number of arguments;	see  below.   Operator	prece-
	      dence is used when there are five	or more	arguments.
	      !	expr True if expr is false.
	      (	expr )
		     Returns  the value	of expr.  This may be used to override
		     the normal	precedence of operators.
	      expr1 -a expr2
		     True if both expr1	and expr2 are true.
	      expr1 -o expr2
		     True if either expr1 or expr2 is true.

	      test and [ evaluate conditional expressions using	a set of rules
	      based on the number of arguments.

	      0	arguments
		     The expression is false.
	      1	argument
		     The expression is true if and only	if the argument	is not
		     null.
	      2	arguments
		     If	the first argument is !, the expression	is true	if and
		     only  if the second argument is null.  If the first argu-
		     ment is one of the	 unary	conditional  operators	listed
		     above  under  CONDITIONAL	EXPRESSIONS, the expression is
		     true if the unary test is true.  If the first argument is
		     not a valid unary conditional operator, the expression is
		     false.
	      3	arguments
		     The following conditions are applied in the order listed.
		     If	 the  second argument is one of	the binary conditional
		     operators listed above under CONDITIONAL EXPRESSIONS, the
		     result of the expression is the result of the binary test
		     using the first and third arguments as operands.  The  -a
		     and  -o  operators	 are  considered binary	operators when
		     there are three arguments.	 If the	first argument	is  !,
		     the  value	is the negation	of the two-argument test using
		     the second	and third arguments.  If the first argument is
		     exactly ( and the third argument is exactly ), the	result
		     is	the one-argument test of the second argument.	Other-
		     wise, the expression is false.
	      4	arguments
		     If	the first argument is !, the result is the negation of
		     the three-argument	expression composed of	the  remaining
		     arguments.	 Otherwise, the	expression is parsed and eval-
		     uated according to	 precedence  using  the	 rules	listed
		     above.
	      5	or more	arguments
		     The  expression  is  parsed  and  evaluated  according to
		     precedence	using the rules	listed above.

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

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

       trap [-lp] [[arg] sigspec ...]
	      The command arg is to be read and	executed when  the  shell  re-
	      ceives signal(s) sigspec.	 If arg	is absent (and there is	a sin-
	      gle sigspec) or -, each specified	signal is reset	to its	origi-
	      nal  disposition	(the value it had upon entrance	to the shell).
	      If arg is	the null string	the signal specified by	 each  sigspec
	      is  ignored by the shell and by the commands it invokes.	If arg
	      is not present and -p has	been supplied, then the	trap  commands
	      associated with each sigspec are displayed.  If no arguments are
	      supplied or if only -p is	given, trap prints the	list  of  com-
	      mands  associated	 with  each  signal.  The -l option causes the
	      shell to print a list of signal names  and  their	 corresponding
	      numbers.	 Each sigspec is either	a signal name defined in <sig-
	      nal.h>, or a signal number.  Signal names	are  case  insensitive
	      and the SIG prefix is optional.

	      If  a  sigspec  is  EXIT (0) the command arg is executed on exit
	      from the shell.  If a sigspec is DEBUG, the command arg is  exe-
	      cuted  before  every  simple command, for	command, case command,
	      select command, every arithmetic for  command,  and  before  the
	      first  command  executes	in a shell function (see SHELL GRAMMAR
	      above).  Refer to	the description	of the extdebug	option to  the
	      shopt builtin for	details	of its effect on the DEBUG trap.  If a
	      sigspec is RETURN, the command arg is executed each time a shell
	      function or a script executed with the . or source builtins fin-
	      ishes executing.

	      If a sigspec is ERR, the command arg is executed whenever	a sim-
	      ple command has a	non-zero exit status, subject to the following
	      conditions.  The ERR trap	is not executed	if the failed  command
	      is part of the command list immediately following	a while	or un-
	      til keyword, part	of the test in an if statement,	part of	a com-
	      mand  executed  in  a  &&	or || list, or if the command's	return
	      value is being inverted via !.  These are	 the  same  conditions
	      obeyed by	the errexit option.

	      Signals ignored upon entry to the	shell cannot be	trapped, reset
	      or listed.  Trapped signals that are not being ignored are reset
	      to  their	 original values in a subshell or subshell environment
	      when one is created.  The	return status is false if any  sigspec
	      is invalid; otherwise trap returns true.

       type [-aftpP] name [name	...]
	      With  no options,	indicate how each name would be	interpreted if
	      used as a	command	name.  If the -t option	is used, type prints a
	      string  which  is	 one  of alias,	keyword, function, builtin, or
	      file if  name  is	 an  alias,  shell  reserved  word,  function,
	      builtin,	or disk	file, respectively.  If	the name is not	found,
	      then nothing is printed, and an exit  status  of	false  is  re-
	      turned.	If the -p option is used, type either returns the name
	      of the disk file that would be executed if name  were  specified
	      as  a command name, or nothing if	``type -t name'' would not re-
	      turn file.  The -P option	forces a PATH search  for  each	 name,
	      even if ``type -t	name'' would not return	file.  If a command is
	      hashed, -p and -P	print the hashed value,	 not  necessarily  the
	      file that	appears	first in PATH.	If the -a option is used, type
	      prints all of the	places that contain an executable named	 name.
	      This  includes  aliases and functions, if	and only if the	-p op-
	      tion is not also used.  The table	of hashed commands is not con-
	      sulted  when  using -a.  The -f option suppresses	shell function
	      lookup, as with the command builtin.  type returns true  if  all
	      of the arguments are found, false	if any are not found.

       ulimit [-HSTabcdefilmnpqrstuvx [limit]]
	      Provides	control	 over the resources available to the shell and
	      to processes started by it, on systems that allow	such  control.
	      The -H and -S options specify that the hard or soft limit	is set
	      for the given resource.  A hard limit cannot be increased	 by  a
	      non-root	user  once it is set; a	soft limit may be increased up
	      to the value of the hard limit.  If neither -H nor -S is	speci-
	      fied, both the soft and hard limits are set.  The	value of limit
	      can be a number in the unit specified for	the resource or	one of
	      the special values hard, soft, or	unlimited, which stand for the
	      current hard limit, the current soft limit, and  no  limit,  re-
	      spectively.   If limit is	omitted, the current value of the soft
	      limit of the resource is printed,	unless the -H option is	given.
	      When  more  than	one  resource is specified, the	limit name and
	      unit are printed before the value.   Other  options  are	inter-
	      preted as	follows:
	      -a     All current limits	are reported
	      -b     The maximum socket	buffer size
	      -c     The maximum size of core files created
	      -d     The maximum size of a process's data segment
	      -e     The maximum scheduling priority ("nice")
	      -f     The  maximum  size	 of files written by the shell and its
		     children
	      -i     The maximum number	of pending signals
	      -l     The maximum size that may be locked into memory
	      -m     The maximum resident set size (many systems do not	 honor
		     this limit)
	      -n     The maximum number	of open	file descriptors (most systems
		     do	not allow this value to	be set)
	      -p     The pipe size in 512-byte blocks (this may	not be set)
	      -q     The maximum number	of bytes in POSIX message queues
	      -r     The maximum real-time scheduling priority
	      -s     The maximum stack size
	      -t     The maximum amount	of cpu time in seconds
	      -u     The maximum number	of processes  available	 to  a	single
		     user
	      -v     The  maximum  amount  of  virtual memory available	to the
		     shell and,	on some	systems, to its	children
	      -x     The maximum number	of file	locks
	      -T     The maximum number	of threads

	      If limit is given, it is the new value of	the specified resource
	      (the -a option is	display	only).	If no option is	given, then -f
	      is assumed.  Values are in 1024-byte increments, except for  -t,
	      which  is	 in seconds, -p, which is in units of 512-byte blocks,
	      and -T, -b, -n, and -u, 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.   In  POSIX  Mode
	      512-byte blocks are used for the `-c' and	`-f' options.

       umask [-p] [-S] [mode]
	      The user file-creation mask is set to mode.  If mode begins with
	      a	digit, it is interpreted as an octal number; otherwise	it  is
	      interpreted  as a	symbolic mode mask similar to that accepted by
	      chmod(1).	 If mode is omitted, the current value of the mask  is
	      printed.	 The  -S  option causes	the mask to be printed in sym-
	      bolic form; the default output is	an octal number.   If  the  -p
	      option is	supplied, and mode is omitted, the output is in	a form
	      that may be reused as input.  The	return status is 0 if the mode
	      was  successfully	 changed  or if	no mode	argument was supplied,
	      and false	otherwise.

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

       unset [-fv] [name ...]
	      For each name, remove the	corresponding  variable	 or  function.
	      If no options are	supplied, or the -v option is given, each name
	      refers to	a shell	variable.  Read-only variables may not be  un-
	      set.   If	-f is specified, each name refers to a shell function,
	      and the function definition is removed.  Each unset variable  or
	      function	is  removed  from the environment passed to subsequent
	      commands.	 If any	of COMP_WORDBREAKS, RANDOM,  SECONDS,  LINENO,
	      HISTCMD,	FUNCNAME,  GROUPS,  or	DIRSTACK  are unset, they lose
	      their special properties,	even if	they are  subsequently	reset.
	      The exit status is true unless a name is readonly.

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

RESTRICTED SHELL
       If bash is started with the name	rbash, or the -r 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	bash with the exception	that the following are
       disallowed or not performed:

       o      changing directories with	cd

       o      setting or unsetting the values of SHELL,	PATH, ENV, or BASH_ENV

       o      specifying command names containing /

       o      specifying a file	name containing	a / as an argument  to	the  .
	      builtin command

       o      specifying  a  filename containing a slash as an argument	to the
	      -p option	to the hash builtin command

       o      importing	function definitions from  the	shell  environment  at
	      startup

       o      parsing  the  value  of  SHELLOPTS from the shell	environment at
	      startup

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

       o      using the	exec builtin command to	replace	the shell with another
	      command

       o      adding or	deleting builtin commands with the -f and  -d  options
	      to the enable builtin command

       o      using  the  enable  builtin  command  to	enable	disabled shell
	      builtins

       o      specifying the -p	option to the command builtin command

       o      turning off restricted mode with set +r or set +o	restricted.

       These restrictions are enforced after any startup files are read.

       When a command that is found to be a shell script is executed (see COM-
       MAND  EXECUTION	above),	 rbash turns off any restrictions in the shell
       spawned to execute the script.

SEE ALSO
       Bash Reference Manual, Brian Fox	and Chet Ramey
       The Gnu Readline	Library, Brian Fox and Chet Ramey
       The Gnu History Library,	Brian Fox and Chet Ramey
       Portable	Operating System Interface (POSIX) Part	2:  Shell  and	Utili-
       ties, IEEE
       sh(1), ksh(1), csh(1)
       emacs(1), vi(1)
       readline(3)

FILES
       /bin/bash
	      The bash executable
       /etc/profile
	      The systemwide initialization file, executed for login shells
       /etc/bash.bash_logout
	      The  systemwide  login shell cleanup file, executed when a login
	      shell exits
       ~/.bash_profile
	      The personal initialization file,	executed for login shells
       ~/.bashrc
	      The individual per-interactive-shell startup file
       ~/.bash_logout
	      The individual login shell cleanup file, executed	when  a	 login
	      shell exits
       ~/.inputrc
	      Individual readline initialization file

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

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

BUG REPORTS
       If you find a bug in bash, 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  bash.   The  latest  version  is  always  available  from
       ftp://ftp.gnu.org/pub/gnu/bash/.

       Once you	have determined	that a bug actually exists,  use  the  bashbug
       command	(from the source package) 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 bug-bash@gnu.org or	posted
       to the Usenet newsgroup gnu.bash.bug.

       ALL bug reports should include:

       The version number of bash
       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

       Comments	and bug	reports	concerning this	manual page should be directed
       to chet.ramey@case.edu.

BUGS
       It's too	big and	too slow.

       There are some subtle differences between bash and traditional versions
       of sh, mostly because of	the POSIX 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-4.2		       2010 December 28			       BASH(1)

NAME | SYNOPSIS | COPYRIGHT | DESCRIPTION | OPTIONS | ARGUMENTS | INVOCATION | DEFINITIONS | RESERVED WORDS | SHELL GRAMMAR | COMMENTS | QUOTING | PARAMETERS | EXPANSION | REDIRECTION | ALIASES | FUNCTIONS | ARITHMETIC EVALUATION | CONDITIONAL EXPRESSIONS | SIMPLE COMMAND EXPANSION | COMMAND EXECUTION | COMMAND EXECUTION ENVIRONMENT | ENVIRONMENT | EXIT STATUS | SIGNALS | JOB CONTROL | PROMPTING | READLINE | HISTORY | HISTORY EXPANSION | SHELL BUILTIN COMMANDS | RESTRICTED SHELL | SEE ALSO | FILES | AUTHORS | BUG REPORTS | BUGS

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