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BASH(1)			    General Commands Manual		       BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [command_string |	file]

COPYRIGHT
       Bash is Copyright (C) 1989-2016 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 description
       of the set builtin command can be used as options when the shell	is in-
       voked.	In  addition, bash interprets the following options when it is
       invoked:

       -c	 If the	-c option is present, then commands are	read from  the
		 first non-option argument command_string.  If there are argu-
		 ments after the command_string, the  first  argument  is  as-
		 signed	 to $0 and any remaining arguments are assigned	to the
		 positional parameters.	 The assignment	to $0 sets the name of
		 the shell, which is used in warning and error messages.
       -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).  See
	      SEE  ALSO	 below	for a reference	to a document that details how
	      posix mode affects bash's	behavior.

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

       --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 (un-
       less -s is specified) 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 filenames	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 an interactive login shell exits, or a non-interactive login shell
       executes	the exit builtin command, bash	reads  and  executes  commands
       from the	file ~/.bash_logout, if	it 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 neither rshd nor sshd  generally  invoke  the  shell  with
       those options or	allow them to be specified.

       If the shell is started with the	effective user (group) id not equal to
       the real	user (group) id, and the -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 newline
       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  coproc  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,
       command's standard error, in addition to	its standard output,  is  con-
       nected  to  command2's standard input through the pipe; it is shorthand
       for 2>&1	|.  This implicit redirection of the  standard	error  to  the
       standard	 output	 is  performed after any redirections specified	by the
       command.

       The return status of a pipeline is the exit status of the last command,
       unless  the  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	or 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.  In most cases a list in  a
       command's  description may be separated from the	rest of	the command by
       one or more newlines, and may be	followed by a newline in  place	 of  a
       semicolon.

       (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,	as if the ext-
	      glob shell option	were enabled.  The = operator is equivalent to
	      ==.  If the nocasematch shell option is enabled,	the  match  is
	      performed	 without  regard to the	case of	alphabetic characters.
	      The return value is 0 if the string matches  (==)	 or  does  not
	      match  (!=)  the pattern,	and 1 otherwise.  Any part of the pat-
	      tern may be quoted to force the quoted portion to	be matched  as
	      a	string.

	      An  additional  binary operator, =~, is available, with the same
	      precedence as == and !=.	When it	is used,  the  string  to  the
	      right  of	the operator is	considered an extended regular expres-
	      sion and matched accordingly (as in 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 nocasematch shell	option
	      is enabled, the match is performed without regard	to the case of
	      alphabetic characters.  Any part of the pattern may be quoted to
	      force the	quoted portion to be matched as	a string.  Bracket ex-
	      pressions	 in  regular  expressions  must	 be treated carefully,
	      since normal quoting  characters	lose  their  meanings  between
	      brackets.	 If the	pattern	is stored in a shell variable, quoting
	      the variable expansion forces the	entire pattern to  be  matched
	      as a string.  Substrings matched by parenthesized	subexpressions
	      within the regular expression are	saved in  the  array  variable
	      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 parenthesized 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 expansion, command substitution, process substitution
	      and  quote  removal.   Each  pattern  examined is	expanded using
	      tilde expansion, parameter and  variable	expansion,  arithmetic
	      expansion,  command  substitution, and process substitution.  If
	      the nocasematch shell option is enabled, the match is  performed
	      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 after the
	      first pattern match.  Using ;& in	place of ;;  causes  execution
	      to  continue  with the list associated with the next set of pat-
	      terns.  Using ;;&	in place of ;; causes the shell	 to  test  the
	      next  pattern list in the	statement, if any, and execute any as-
	      sociated 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 coprocess is executed, the	shell  creates
       an  array  variable (see	Arrays below) named NAME in the	context	of the
       executing shell.	 The standard output of	command	 is  connected	via  a
       pipe  to	 a  file  descriptor in	the executing shell, and that file de-
       scriptor	is assigned to NAME[0].	 The standard input of command is con-
       nected via a pipe to a file descriptor in the executing shell, and that
       file descriptor is assigned to NAME[1].	This pipe is  established  be-
       fore 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 file descriptors are
       not available in	subshells.  The	process	ID of the shell	spawned	to ex-
       ecute 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  ter-
       minate.

       Since  the  coprocess is	created	as an asynchronous command, the	coproc
       command always returns success.	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,  with
	      one  exception:  If  the function	reserved word is used, but the
	      parentheses are not supplied, the	 braces	 are  required.	  com-
	      pound-command is executed	whenever name is specified as the name
	      of a simple command.  When in posix mode,	name may  not  be  the
	      name  of	one  of	 the POSIX special builtins.  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 exe-
	      cuted, 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, !.  When the shell is	in posix mode,
       the  !  has  no special meaning within double quotes, even when history
       expansion is enabled.  The characters $	and  `	retain	their  special
       meaning	within double quotes.  The backslash retains its special mean-
       ing 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
	      \?     question mark
	      \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 (declaration commands).
       When in posix mode, these builtins may appear in	a command after	one or
       more  instances	of  the	 command  builtin  and retain these assignment
       statement properties.

       In the context where an assignment statement is assigning a value to  a
       shell variable or array index, the += operator can be used to append to
       or add to the variable's	previous value.	 This  includes	 arguments  to
       builtin	commands  such	as  declare  that accept assignment statements
       (declaration commands).	When +=	is applied to a	variable for which the
       integer attribute has been set, value is	evaluated as an	arithmetic ex-
       pression	and added to the variable's current value, which is also eval-
       uated.	When +=	is applied to an array variable	using compound assign-
       ment (see Arrays	below),	the variable's value is	not unset  (as	it  is
       when  using  =),	 and new values	are appended to	the array beginning at
       one greater than	the array's maximum  index  (for  indexed  arrays)  or
       added  as additional key-value pairs in an associative array.  When ap-
       plied to	a string-valued	variable, value	is expanded  and  appended  to
       the variable's value.

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

   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  is not within double quotes, each	positional pa-
	      rameter expands to a separate word.  In  contexts	 where	it  is
	      performed, those words are subject to further word splitting and
	      pathname expansion.  When	the  expansion	occurs	within	double
	      quotes,  it  expands to a	single word with the value of each pa-
	      rameter separated	by the first  character	 of  the  IFS  special
	      variable.	  That	is, "$*" is equivalent to "$1c$2c...", where c
	      is the first character of	the value of the IFS variable.	If IFS
	      is  unset,  the  parameters  are separated by spaces.  If	IFS is
	      null, the	parameters are joined without intervening separators.
       @      Expands to the positional	parameters, starting from  one.	  When
	      the  expansion  occurs  within double quotes, each parameter ex-
	      pands to a separate word.	 That is, "$@" 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 job most recently placed into
	      the background, whether executed as an asynchronous  command  or
	      using the	bg builtin (see	JOB CONTROL below).
       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 filename 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 filename 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; however,
	      unsetting	array elements currently does not cause	aliases	to  be
	      removed from the alias list.  If BASH_ALIASES is unset, it loses
	      its special properties, even if it is subsequently reset.
       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;
	      however,	unsetting array	elements currently does	not cause com-
	      mand names to be removed from the	hash table.  If	 BASH_CMDS  is
	      unset,  it  loses	 its  special properties, even if it is	subse-
	      quently reset.
       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_LOADABLES_PATH
	      A	colon-separated	list of	directories in which the  shell	 looks
	      for  dynamically	loadable builtins specified by the enable com-
	      mand.
       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 within each subshell or subshell environment
	      when the shell begins executing in that environment.   The  ini-
	      tial 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.  If FUNCNAME  is	unset,
	      it  loses	its special properties,	even if	it is subsequently re-
	      set.

	      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.
	      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_COMPAT
	      The value	is used	to set the shell's compatibility  level.   See
	      the  description	of the shopt builtin below under SHELL BUILTIN
	      COMMANDS for a description of the	various	 compatibility	levels
	      and  their  effects.   The  value	may be a decimal number	(e.g.,
	      4.2) or an integer (e.g.,	42) corresponding to the desired  com-
	      patibility  level.   If BASH_COMPAT is unset or set to the empty
	      string, the compatibility	level is set to	the  default  for  the
	      current  version.	  If BASH_COMPAT is set	to a value that	is not
	      one of the valid compatibility levels, the shell prints an error
	      message  and sets	the compatibility level	to the default for the
	      current version.	The valid compatibility	levels	correspond  to
	      the  compatibility  options  accepted  by	 the shopt builtin de-
	      scribed below (for example, compat42 means that 4.2 and  42  are
	      valid values).  The current version is also a valid value.
       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 filename.
	      PATH is not used to search for the resultant filename.
       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".
       CHILD_MAX
	      Set the number of	exited child status values for	the  shell  to
	      remember.	  Bash will not	allow this value to be decreased below
	      a	POSIX-mandated minimum,	and there is  a	 maximum  value	 (cur-
	      rently  8192)  that  this	 may not exceed.  The minimum value is
	      system-dependent.
       COLUMNS
	      Used by the select compound command to  determine	 the  terminal
	      width  when  printing selection lists.  Automatically set	if the
	      checkwinsize option is enabled or	in an interactive  shell  upon
	      receipt 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).  Each ar-
	      ray element contains one possible	completion.
       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.
       EXECIGNORE
	      A	 colon-separated list of shell patterns	(see Pattern Matching)
	      defining the list	of filenames to	be ignored by  command	search
	      using  PATH.  Files whose	full pathnames match one of these pat-
	      terns are	not considered executable files	for  the  purposes  of
	      completion and command execution via PATH	lookup.	 This does not
	      affect the behavior of the [, test, and [[ commands.  Full path-
	      names  in	 the command hash table	are not	subject	to EXECIGNORE.
	      Use this variable	to ignore shared library files that  have  the
	      executable  bit  set, but	are not	executable files.  The pattern
	      matching honors the setting of the extglob shell option.
       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 a shell exits.
       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,  to  contain  no more than	that number of
	      lines by removing	the oldest entries.  The history file is  also
	      truncated	 to this size after writing it when a shell exits.  If
	      the value	is 0, the history file	is  truncated  to  zero	 size.
	      Non-numeric  values  and	numeric	 values	less than zero inhibit
	      truncation.  The shell sets the default value to	the  value  of
	      HISTSIZE after reading any startup files.
       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.  The	pattern	match-
	      ing honors the setting of	the extglob shell option.
       HISTSIZE
	      The number of commands to	remember in the	command	 history  (see
	      HISTORY  below).	 If  the value is 0, commands are not saved in
	      the history list.	 Numeric values	less than zero result in every
	      command  being  saved  on	 the history list (there is no limit).
	      The shell	sets the  default  value  to  500  after  reading  any
	      startup files.
       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.
       LC_TIME
	      This variable determines the locale category used	for  data  and
	      time formatting.
       LINES  Used  by	the  select  compound  command to determine the	column
	      length for printing selection lists.  Automatically set  if  the
	      checkwinsize  option  is enabled or in an	interactive shell upon
	      receipt 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	filenames to be	checked	for mail.  The
	      message to be printed when mail arrives in a particular file may
	      be specified by separating the filename from the message with  a
	      `?'.   When  used	 in the	text of	the message, $_	expands	to the
	      name of the current mailfile.  Example:
	      MAILPATH='/var/mail/bfox?"You  have  mail":~/shell-mail?"$_  has
	      mail!"'
	      Bash  can	be configured to supply	a default value	for this vari-
	      able (there is no	value by default), but	the  location  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/local/bin:/usr/lo-
	      cal/sbin:/usr/bin:/usr/sbin:/bin:/sbin''.
       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.
       PS0    The  value  of  this parameter is	expanded (see PROMPTING	below)
	      and displayed by interactive shells after	reading	a command  and
	      before the command is executed.
       PS1    The  value  of  this parameter is	expanded (see PROMPTING	below)
	      and used as the primary prompt string.   The  default  value  is
	      ``\u@\h\$	''.
       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\t%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 a line of input
	      after issuing the	primary	prompt.	 Bash terminates after waiting
	      for that number of seconds if a complete line of 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 ref-
       erenced using arbitrary strings.	 Unless	otherwise noted, indexed array
       indices must be non-negative integers.

       An  indexed  array is created automatically if any variable is assigned
       to using	the syntax name[subscript]=value.  The subscript is treated as
       an arithmetic expression	that must evaluate to a	number.	 To explicitly
       declare an indexed array, use declare -a	name (see SHELL	 BUILTIN  COM-
       MANDS  below).	declare	 -a name[subscript] is also accepted; the sub-
       script 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 anything but
       string.	When assigning to indexed arrays, if the optional brackets and
       subscript  are supplied,	that index is assigned to; otherwise the index
       of the element assigned is the last index assigned to by	the  statement
       plus one.  Indexing starts at zero.

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

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

       Any  element  of	 an  array may be referenced using ${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.  If	the subscript used to reference	an element of an indexed array
       evaluates  to a number less than	zero, it is interpreted	as relative to
       one greater than	the maximum index of the array,	 so  negative  indices
       count back from the end of the array, and an index of -1	references the
       last element.

       Referencing an array variable without a subscript is equivalent to ref-
       erencing	 the array with	a subscript of 0.  Any reference to a variable
       using a valid subscript is legal, and bash will create an array if nec-
       essary.

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

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

       The unset builtin is used to destroy arrays.  unset name[subscript] de-
       stroys the array	element	at index subscript.   Negative	subscripts  to
       indexed	arrays are interpreted as described above.  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, parameter
       and  variable expansion,	arithmetic expansion, and command substitution
       (done in	a left-to-right	fashion); word splitting; and pathname	expan-
       sion.

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

       After these expansions are performed, quote characters present  in  the
       original	 word  are  removed  unless  they  have	been quoted themselves
       (quote removal).

       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, using  the  de-
       fault C locale.	Note that both x and y must be of the same type.  When
       the increment is	supplied, it is	used as	the  difference	 between  each
       term.  The default increment is 1 or -1 as appropriate.

       Brace expansion is performed before any other expansions, and any char-
       acters special to other expansions are preserved	in the result.	It  is
       strictly	 textual.  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 filenames with tildes	in as-
       signments  to PATH, MAILPATH, and CDPATH, and the shell assigns the ex-
       panded 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.  The parameter is a shell
	      parameter	 as  described above PARAMETERS) or an array reference
	      (Arrays).

       If the first character of parameter is an exclamation  point  (!),  and
       parameter  is not a nameref, it introduces a level of variable indirec-
       tion.  Bash uses	the value of the variable formed from the rest of  pa-
       rameter as the name of the variable; this variable is then expanded and
       that value is used in the rest of the  substitution,  rather  than  the
       value  of  parameter  itself.  This is known as indirect	expansion.  If
       parameter is a nameref, this expands to the name	of the variable	refer-
       enced  by  parameter instead of performing the complete indirect	expan-
       sion.  The exceptions to	this are the  expansions  of  ${!prefix*}  and
       ${!name[@]}  described  below.	The exclamation	point must immediately
       follow the left brace in	order to introduce indirection.

       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 (e.g., :-), bash tests for a	 parameter  that  is  unset  or	 null.
       Omitting	 the  colon results in a test only for a parameter that	is un-
       set.

       ${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  the
	      value  of	 parameter starting at the character specified by off-
	      set.  If parameter is @, an indexed array	subscripted by @ or *,
	      or  an  associative  array name, the results differ as described
	      below.  If length	is omitted, expands to the  substring  of  the
	      value of parameter starting at the character specified by	offset
	      and extending to the end of the value.  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	in characters from the end of the value	of pa-
	      rameter.	 If length evaluates to	a number less than zero, it is
	      interpreted as an	offset in characters from the end of the value
	      of  parameter rather than	a number of characters,	and the	expan-
	      sion is the characters between offset  and  that	result.	  Note
	      that  a  negative	 offset	must be	separated from the colon by at
	      least one	space to avoid being confused with the :- expansion.

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

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

	      Substring	expansion applied to an	associative array produces un-
	      defined results.

	      Substring	 indexing  is zero-based unless	the positional parame-
	      ters are used, in	which case the indexing	starts	at  1  by  de-
	      fault.   If offset is 0, and the positional parameters are used,
	      $0 is prefixed 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.  If parameter is an indexed
	      array  name subscripted by a negative number, that number	is in-
	      terpreted	as relative to one greater than	the maximum  index  of
	      parameter,  so  negative	indices	count back from	the end	of the
	      array, and an index of -1	references the last element.

       ${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 the nocasematch shell	option
	      is enabled, the match is performed without regard	to the case of
	      alphabetic characters.  If parameter is @	or *, the substitution
	      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 operation  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.  Each character in
	      the  expanded value of parameter is tested against pattern, and,
	      if it matches the	pattern, its case is converted.	  The  pattern
	      should  not attempt to match more	than one character.  The ^ op-
	      erator converts lowercase	letters	matching pattern to uppercase;
	      the , operator converts matching uppercase letters to lowercase.
	      The ^^ and ,, expansions convert each matched character  in  the
	      expanded	value;	the  ^ and , expansions	match and convert only
	      the first	character in the expanded value.  If pattern is	 omit-
	      ted,  it is treated like a ?, which matches every	character.  If
	      parameter	is @ or	*, the case modification 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	case modification operation is applied to each
	      member of	the array in turn, and the expansion is	the  resultant
	      list.

       ${parameter@operator}
	      Parameter	transformation.	 The expansion is either a transforma-
	      tion of the value	of parameter or	 information  about  parameter
	      itself,  depending on the	value of operator.  Each operator is a
	      single letter:

	      Q	     The expansion is a	string that is the value of  parameter
		     quoted in a format	that can be reused as input.
	      E	     The  expansion is a string	that is	the value of parameter
		     with backslash escape  sequences  expanded	 as  with  the
		     $'...' quoting mechansim.
	      P	     The expansion is a	string that is the result of expanding
		     the value of parameter as if it were a prompt string (see
		     PROMPTING below).
	      A	     The  expansion  is	 a string in the form of an assignment
		     statement or declare command  that,  if  evaluated,  will
		     recreate parameter	with its attributes and	value.
	      a	     The  expansion is a string	consisting of flag values rep-
		     resenting parameter's attributes.

	      If parameter is @	or *, the 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 case modification	operation is applied to	each member of
	      the array	in turn, and the expansion is the resultant list.

	      The result of the	expansion is subject  to  word	splitting  and
	      pathname expansion as described below.

   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	in a subshell environ-
       ment and	replacing the command 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 com-
       mand 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 and variable expansion, com-
       mand substitution, and quote removal.  The result  is  treated  as  the
       arithmetic  expression  to  be evaluated.  Arithmetic expansions	may be
       nested.

       The evaluation is performed according to	the rules listed  below	 under
       ARITHMETIC EVALUATION.  If expression is	invalid, bash prints a message
       indicating failure and no substitution occurs.

   Process Substitution
       Process substitution allows a process's input or	output to be  referred
       to  using  a  filename.	 It takes the form of <(list) or >(list).  The
       process list is run asynchronously, and its input or output appears  as
       a filename.  This filename is passed as an argument to the current com-
       mand as the result of the expansion.  If	 the  >(list)  form  is	 used,
       writing	to  the	file will provide input	for list.  If the <(list) form
       is used,	the file passed	as an argument should be read  to  obtain  the
       output of list.	Process	substitution is	supported on systems that sup-
       port named pipes	(FIFOs)	or the /dev/fd method of naming	open files.

       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 using these characters as
       field  terminators.   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 sequence 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,
       tab, and	newline	are ignored at the beginning and end of	the  word,  as
       long  as	the whitespace character is in the value of IFS	(an IFS	white-
       space character).  Any character	in IFS that  is	 not  IFS  whitespace,
       along with any adjacent IFS whitespace characters, 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	and passed to commands
       as empty	strings.  Unquoted implicit null arguments, resulting from the
       expansion of parameters that have no values, are	removed.  If a parame-
       ter with	no value is expanded within double quotes, a null argument re-
       sults and is retained and passed	to a command as	an empty string.  When
       a quoted	null argument appears as part of a  word  whose	 expansion  is
       non-null, the null argument is removed.	That is, the word -d'' becomes
       -d after	word splitting and null	argument removal.

       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 filenames	matching the pattern (see Pat-
       tern Matching below).  If no matching  filenames	 are  found,  and  the
       shell  option  nullglob is not enabled, the word	is left	unchanged.  If
       the nullglob option is set, and no matches are found, the word  is  re-
       moved.	If the failglob	shell option is	set, and no matches are	found,
       an error	message	is printed and the command is not  executed.   If  the
       shell  option nocaseglob	is enabled, the	match is performed without re-
       gard to the case	of alphabetic characters.  When	a pattern is used  for
       pathname	 expansion, the	character ``.''	 at the	start of a name	or im-
       mediately following a slash must	 be  matched  explicitly,  unless  the
       shell option dotglob is set.  When matching a pathname, the slash char-
       acter must always be matched explicitly.	 In  other  cases,  the	 ``.''
       character is not	treated	specially.  See	the description	of shopt below
       under SHELL BUILTIN COMMANDS for	a description of the nocaseglob, null-
       glob, 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 filename
       that also matches one of	the patterns in	GLOBIGNORE is removed from the
       list of matches.	 If the	nocaseglob option is set, the matching against
       the  patterns  in  GLOBIGNORE is	performed without regard to case.  The
       filenames ``.''	and ``..''  are	always ignored when GLOBIGNORE is  set
       and  not	null.  However,	setting	GLOBIGNORE to a	non-null value has the
       effect of enabling the dotglob shell option, so all other filenames be-
       ginning	with a ``.''  will match.  To get the old behavior of ignoring
       filenames beginning with	a ``.'', make ``.*''  one of the  patterns  in
       GLOBIGNORE.   The  dotglob option is disabled when GLOBIGNORE is	unset.
       The pattern matching honors the setting of the extglob shell option.

       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 falls 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 values of the LC_COLLATE or  LC_ALL  shell	 vari-
		     ables,  if	set.  To obtain	the traditional	interpretation
		     of	 range	expressions,  where  [a-d]  is	equivalent  to
		     [abcd],  set  value of the	LC_ALL shell variable to C, or
		     enable the	globasciiranges	shell  option.	 A  -  may  be
		     matched by	including it as	the first or last character in
		     the set.  A ] may be matched by including it as the first
		     character in the set.

		     Within  [ and ], 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.

       If the extglob shell option is enabled using the	shopt builtin, 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 fol-
       lowing 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
	      !(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	allows
       commands' file handles to be duplicated,	opened,	closed,	made to	 refer
       to different files, and can change the files the	command	reads from and
       writes to.  Redirection may also	be used	to modify file handles in  the
       current	shell execution	environment.  The following redirection	opera-
       tors may	precede	or appear anywhere within a simple command or may fol-
       low  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 or equal to 10 and assign	it to varname.
       If >&- or <&- is	preceded by {varname}, the value  of  varname  defines
       the file	descriptor to close.

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

       The  word  following the	redirection operator in	the following descrip-
       tions, unless otherwise noted, is subjected to brace  expansion,	 tilde
       expansion,  parameter  and  variable  expansion,	 command substitution,
       arithmetic expansion,  quote  removal,  pathname	 expansion,  and  word
       splitting.  If it expands to more than one word,	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.  If the operating system on
       which bash is running provides these special files, bash	will use them;
       otherwise it will emulate them internally with the  behavior  described
       below.

	      /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 the corresponding TCP 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 the corresponding UDP socket.

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

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

   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

       When using the second form, word	may not	expand to a number or  -.   If
       it  does,  other	 redirection operators apply (see Duplicating File De-
       scriptors below)	for compatibility reasons.

   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

       (see Duplicating	File Descriptors below).

   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	(or file descriptor n if n is specified) for a
       command.

       The format of here-documents is:

	      [n]<<[-]word
		      here-document
	      delimiter

       No parameter and	variable expansion, command  substitution,  arithmetic
       expansion,  or pathname expansion is performed on word.	If any part of
       word is quoted, the delimiter is	the result of quote removal  on	 word,
       and  the	 lines	in the here-document are not expanded.	If word	is un-
       quoted, all lines of the	here-document are subjected to	parameter  ex-
       pansion,	 command substitution, and arithmetic expansion, the character
       sequence	\<newline> is ignored, and \ must be used to quote the charac-
       ters \, $, 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:

	      [n]<<<word

       The word	undergoes brace	 expansion,  tilde  expansion,	parameter  and
       variable	 expansion,  command  substitution,  arithmetic	expansion, and
       quote removal.  Pathname	expansion and  word  splitting	are  not  per-
       formed.	 The result is supplied	as a single string, with a newline ap-
       pended, to the command on its standard input (or	file descriptor	n if n
       is specified).

   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.  If word evaluates to -, file descriptor n is
       closed.	As a special case, if n	is omitted, and	word does  not	expand
       to  one or more digits or -, 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	command.  As a
       consequence, aliases defined in a function are not available until  af-
       ter  that  function  is executed.  To be	safe, always put alias defini-
       tions 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,	 the  ((  com-
       pound command, 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  fol-
       lowing list of operators	is grouped into	levels of equal-precedence op-
       erators.	 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.	 When specifying n, 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 uppercase letters may be used interchangeably  to	repre-
       sent numbers between 10 and 35.

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

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.  Bash	handles	 several  filenames  specially
       when  they  are	used in	expressions.  If the operating system on which
       bash is running provides	these special files, bash will use them;  oth-
       erwise  it will emulate them internally with this behavior: If any file
       argument	to one of the primaries	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).
       -R varname
	      True  if	the shell variable varname is set and is a name	refer-
	      ence.
       -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.	When used with the [[ command,
	      this performs pattern matching as	described above	(Compound Com-
	      mands).

       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 filename of	the command and	passed to that command in its environ-
       ment.

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,	generally  in-
       valid options or	missing	arguments.

       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 displays PS0 after it
       reads a command but before executing  it.   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.
       blink-matching-paren (Off)
	      If set to	On, readline attempts to briefly move the cursor to an
	      opening parenthesis when a closing parenthesis is	inserted.
       colored-completion-prefix (Off)
	      If  set  to  On, when listing completions, readline displays the
	      common prefix of the set of possible completions using a differ-
	      ent  color.   The	 color definitions are taken from the value of
	      the LS_COLORS environment	variable.
       colored-stats (Off)
	      If set to	On, readline displays possible completions using  dif-
	      ferent  colors  to  indicate their file type.  The color defini-
	      tions are	taken from the	value  of  the	LS_COLORS  environment
	      variable.
       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-display-width	(-1)
	      The  number  of  screen columns used to display possible matches
	      when performing completion.  The value is	ignored	if it is  less
	      than  0 or greater than the terminal screen width.  A value of 0
	      will cause matches to be displayed one per  line.	  The  default
	      value is -1.
       completion-ignore-case (Off)
	      If set to	On, readline performs filename matching	and completion
	      in a case-insensitive fashion.
       completion-map-case (Off)
	      If set to	On, and	completion-ignore-case	is  enabled,  readline
	      treats  hyphens  (-) and underscores (_) as equivalent when per-
	      forming case-insensitive filename	matching and completion.
       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).   The  default is On, but readline	will set it to
	      Off if the locale	contains eight-bit characters.
       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.
       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.
       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.
       enable-bracketed-paste (Off)
	      When set to On, readline will configure the terminal  in	a  way
	      that will	enable it to insert each paste into the	editing	buffer
	      as a single string of characters,	instead	of treating each char-
	      acter  as	 if it had been	read from the keyboard.	 This can pre-
	      vent pasted characters from being	interpreted  as	 editing  com-
	      mands.
       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 (unset)
	      Set the maximum number of	history	entries	saved in  the  history
	      list.   If set to	zero, any existing history entries are deleted
	      and no new entries are saved.  If	set to a value less than zero,
	      the  number  of history entries is not limited.  By default, the
	      number of	history	entries	is set to the value  of	 the  HISTSIZE
	      shell  variable.	If an attempt is made to set history-size to a
	      non-numeric value, the maximum number of history entries will be
	      set to 500.
       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 eighth	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.  The default is Off,
	      but readline will	set it to On if	the locale contains  eight-bit
	      characters.
       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.
       emacs-mode-string (@)
	      This string is displayed immediately before the last line	of the
	      primary  prompt when emacs editing mode is active.  The value is
	      expanded like a key binding, so the standard set	of  meta-  and
	      control  prefixes	 and  backslash	escape sequences is available.
	      Use the \1 and \2	escapes	to begin and  end  sequences  of  non-
	      printing	characters, which can be used to embed a terminal con-
	      trol sequence into the mode string.
       keyseq-timeout (500)
	      Specifies	the duration readline will wait	for a  character  when
	      reading  an ambiguous key	sequence (one that can form a complete
	      key sequence using the input read	so far,	or can take additional
	      input  to	 complete  a longer key	sequence).  If no input	is re-
	      ceived within the	timeout, readline will	use  the  shorter  but
	      complete	key sequence.  The value is specified in milliseconds,
	      so a value of 1000 means that readline will wait one second  for
	      additional  input.  If this variable is set to a value less than
	      or equal to zero,	or to a	non-numeric value, readline will  wait
	      until  another  key  is  pressed to decide which key sequence to
	      complete.
       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.
	      The default is Off, but readline will set	it to On if the	locale
	      contains eight-bit characters.
       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.
       show-mode-in-prompt (Off)
	      If set to	On, add	a character to the beginning of	the prompt in-
	      dicating the editing mode: emacs (@), vi command (:) or  vi  in-
	      sertion (+).
       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.
       vi-cmd-mode-string ((cmd))
	      This string is displayed immediately before the last line	of the
	      primary  prompt  when  vi	 editing mode is active	and in command
	      mode.  The value is expanded like	a key binding, so the standard
	      set of meta- and control prefixes	and backslash escape sequences
	      is available.  Use the \1	and \2 escapes to begin	 and  end  se-
	      quences of non-printing characters, which	can be used to embed a
	      terminal control sequence	into the mode string.
       vi-ins-mode-string ((ins))
	      This string is displayed immediately before the last line	of the
	      primary  prompt  when vi editing mode is active and in insertion
	      mode.  The value is expanded like	a key binding, so the standard
	      set of meta- and control prefixes	and backslash escape sequences
	      is available.  Use the \1	and \2 escapes to begin	 and  end  se-
	      quences of non-printing characters, which	can be used to embed a
	      terminal control sequence	into the mode string.
       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	both the 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 word, 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
       end-of-file (usually C-d)
	      The character indicating end-of-file as  set,  for  example,  by
	      ``stty''.	  If  this character is	read when there	are no charac-
	      ters on the line,	and point is at	the  beginning	of  the	 line,
	      Readline interprets it as	the end	of input and returns EOF.
       delete-char (C-d)
	      Delete the character at point.  If this function is bound	to the
	      same character as	the tty	EOF character, as C-d commonly is, see
	      above for	the effects.
       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
	      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
	      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 nor minus sign, the argument	 count	for  the  next
	      command  is multiplied by	four.  The argument count is initially
	      one, so executing	this function the first	time makes  the	 argu-
	      ment count four, a second	time makes the argument	count sixteen,
	      and so on.

   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.
       print-last-kbd-macro ()
	      Print  the  last keyboard	macro defined in a format suitable for
	      the inputrc file.

   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 filenames 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	filenames is inserted, replac-
	      ing the word.  If	a numeric argument is supplied,	an asterisk 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 ($1) is the name of the command whose arguments are  be-
       ing  completed,	the  second argument ($2) is the word being completed,
       and the third argument ($3) is the word preceding the word  being  com-
       pleted on the current command line.  No filtering of the	generated com-
       pletions	against	the word being completed is performed; the function or
       command has complete freedom in generating the matches.

       Any  function specified with -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,	one per	array element.

       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.	 If the	nocasematch  shell  option  is
       enabled,	 the  match  is	performed without regard to the	case of	alpha-
       betic characters.

       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 -o bashdefault	-o default

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.	 If  HISTFILE-
       SIZE  is	unset, or set to null, a non-numeric value, or a numeric value
       less than zero, the history file	is not truncated.   When  the  history
       file  is	 read, lines beginning with the	history	comment	character fol-
       lowed immediately by a digit are	interpreted as timestamps for the pre-
       ceding history line.  These timestamps are optionally displayed depend-
       ing on the value	of the HISTTIMEFORMAT variable.	  When	a  shell  with
       history	enabled	 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
       overwritten.   If  HISTFILE  is	unset,	or  if the history file	is un-
       writable, the history is	not saved.  If the HISTTIMEFORMAT variable  is
       set,  time stamps are written to	the history file, marked with the his-
       tory comment character, so they may be preserved	across shell sessions.
       This  uses the history comment character	to distinguish timestamps from
       other history lines.  After saving the history,	the  history  file  is
       truncated  to contain no	more than HISTFILESIZE lines.  If HISTFILESIZE
       is unset, or set	to null, a non-numeric value, or a numeric value  less
       than zero, the history file is not truncated.

       The  builtin  command 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, but the history expansion character is also treated
       as quoted if it immediately precedes the	closing	double quote in	a dou-
       ble-quoted string.

       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  position
	      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	word.  This is usually the last	argument, but will ex-
	      pand to the zeroth word if there is only one word	in the line.
       %      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	filename component, leaving only the head.
       t      Remove all leading filename 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, return,  break,  con-
       tinue,  let,  and shift builtins	accept and process arguments beginning
       with - without 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  interpreta-
       tion.
       : [arguments]
	      No  effect;  the command does nothing beyond expanding arguments
	      and performing any specified redirections.  The return status is
	      zero.

	.  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,
	      filenames	in PATH	are used  to  find  the	 directory  containing
	      filename.	 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.  If the -T option is enabled,
	      source inherits any trap on DEBUG; if it is not, any DEBUG  trap
	      string  is  saved	 and  restored	around the call	to source, and
	      source unsets the	DEBUG trap while it executes.  If  -T  is  not
	      set,  and	the sourced file changes the DEBUG trap, the new value
	      is retained when source completes.  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]	[-lpsvPSVX]
       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 [-m	keymap]	keyseq: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  (vi-move
		     is	 also  a  synonym); emacs is equivalent	to emacs-stan-
		     dard.
	      -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.
	      -X     List all key sequences bound to shell  commands  and  the
		     associated	commands in a format that can be reused	as in-
		     put.

	      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 0 unless n is	not  greater  than  or
	      equal to 1.

       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.  if dir  is	not  supplied,
	      the  value of the	HOME shell variable is the default.  Any addi-
	      tional arguments following dir are ignored.  The variable	CDPATH
	      defines  the  search path	for the	directory containing dir: each
	      directory	name in	CDPATH is searched for dir.   Alternative  di-
	      rectory  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 option causes cd to	 use  the  physical  directory
	      structure	 by  resolving symbolic	links while traversing dir and
	      before processing	instances of ..	in dir (see also the -P	option
	      to the set builtin command); the -L option forces	symbolic links
	      to be followed by	resolving the link after processing  instances
	      of .. in dir.  If	.. appears in dir, it is processed by removing
	      the immediately previous pathname	component from dir, back to  a
	      slash  or	 the  beginning	 of dir.  If the -e option is supplied
	      with -P, and the current working directory  cannot  be  success-
	      fully  determined	 after	a successful directory change, cd will
	      return an	unsuccessful status.  On systems that support it,  the
	      -@  option  presents  the	 extended attributes associated	with a
	      file as a	directory.  An argument	of - is	converted  to  $OLDPWD
	      before the directory change is attempted.	 If a non-empty	direc-
	      tory 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  filename
	      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.
		      noquote Tell readline not	to quote the  completed	 words
			      if  they are filenames (quoting filenames	is the
			      default).
		      nosort  Tell readline not	to sort	the list  of  possible
			      completions alphabetically.
		      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 the function is executed, the
		      first argument ($1) is the name of the command whose ar-
		      guments are being	completed, the second argument ($2) is
		      the word being completed,	and the	third argument ($3) is
		      the  word	preceding the word being completed on the cur-
		      rent command line.  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.  The return value is 0 unless	n is not greater  than
	      or equal to 1.

       declare [-aAfFgilnrtux] [-p] [name[=value] ...]
       typeset [-aAfFgilnrtux] [-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, other than -f  and  -F,
	      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  at-
	      tributes	and values of all shell	variables.  The	-f option will
	      restrict the display to shell functions.	The -F option inhibits
	      the  display of function definitions; 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 each
	      name is defined are displayed 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 func-
	      tion.   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.
	      -n     Give  each	 name  the nameref attribute, making it	a name
		     reference to another variable.  That  other  variable  is
		     defined  by  the  value of	name.  All references, assign-
		     ments, and	attribute modifications	to name, except	 those
		     using  or changing	the -n attribute itself, are performed
		     on	the variable referenced	by name's value.  The  nameref
		     attribute cannot be applied to array variables.
	      -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, declare and typeset make each name	local, as with
	      the local	command, unless	the -g option is supplied.  If a vari-
	      able name	is followed by =value, the value of  the  variable  is
	      set  to  value.  When using -a or	-A and the compound assignment
	      syntax to	create array variables,	additional attributes  do  not
	      take effect until	subsequent assignments.	 The return value is 0
	      unless an	invalid	option is encountered, an attempt is  made  to
	      define  a	 function  using ``-f foo=bar'', an attempt is made to
	      assign a value to	a readonly variable, an	attempt	is made	to as-
	      sign a value to an array variable	without	using the compound as-
	      signment syntax (see Arrays above), one of the names  is	not  a
	      valid  shell variable name, an attempt is	made to	turn off read-
	      only status for a	readonly variable, an attempt is made to  turn
	      off array	status for an array variable, or an attempt is made to
	      display a	non-existent function with -f.

       dirs [-clpv] [+n] [-n]
	      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.  The current directory is always the first	direc-
	      tory in the stack.
	      -c     Clears  the  directory  stack  by deleting	all of the en-
		     tries.
	      -l     Produces a	listing	 using	full  pathnames;  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.
	      +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.

	      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 ... |	pid ...	]
	      Without  options,	 remove	 each jobspec from the table of	active
	      jobs.  If	jobspec	is not present,	and neither the	-a nor the  -r
	      option  is  supplied, 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 re-
	      ceives a SIGHUP.	If no jobspec is supplied, the -a option means
	      to  remove or mark all jobs; the -r option without a jobspec ar-
	      gument restricts operation 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 0 unless a write error occurs.   If	-n  is
	      specified, the trailing newline is suppressed.  If the -e	option
	      is given,	 interpretation	 of  the  following  backslash-escaped
	      characters  is  enabled.	The -E option disables the interpreta-
	      tion of these escape characters, 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  es-
	      cape  characters by default.  echo does not interpret -- to mean
	      the end of options.  echo	interprets the	following  escape  se-
	      quences:
	      \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 execfail shell	option is enabled.  In that  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 names of all exported
	      variables	is printed.  The -n option causes the export  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  sup-
	      plied with a name	that is	not a function.

       fc [-e ename] [-lnr] [first] [last]
       fc -s [pat=rep] [cmd]
	      The  first  form	selects	a range	of commands from first to last
	      from the history list and	 displays  or  edits  and  re-executes
	      them.   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 current 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	other-
	      wise.   If first is not specified	it is set to the previous com-
	      mand 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.  Command is intepreted	 the  same  as
	      first  above.  A useful alias to use with	this is	``r="fc	-s"'',
	      so that typing ``r cc'' runs the	last  command  beginning  with
	      ``cc'' and typing	``r'' re-executes the last command.

	      If  the  first form is used, the return value is 0 unless	an 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  filename	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  to  the	history	 file.
		     These  are	 history  lines	entered	since the beginning of
		     the current bash session, but not already appended	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 append them  to
		     the current history list.
	      -w     Write the current history list to the history file, over-
		     writing 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 following history entry.  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     Display only running jobs.
	      -s     Display only 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|-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.  The	-L  option  is
	      equivalent  to -l.  kill returns true if at least	one signal was
	      successfully sent, or false if an	error occurs or	an invalid op-
	      tion 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.	If name	is -, the set of shell options
	      is made local to the function in which local is  invoked:	 shell
	      options  changed	using  the set builtin inside the function are
	      restored to their	original values	 when  the  function  returns.
	      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	[-d  delim] [-n	count] [-O origin] [-s count] [-t] [-u fd] [-C
       callback] [-c quantum] [array]
       readarray [-d delim] [-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:
	      -d     The first character of delim is used  to  terminate  each
		     input line, rather	than newline.
	      -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	delim (default 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 in the same	way as echo -e.
	      %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.  If no  ar-
		     gument is specified, conversion behaves as	if -1 had been
		     given.  This is an	exception to the usual	printf	behav-
		     ior.

	      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, pushd exchanges the top  two  di-
	      rectories	 and  returns  0, unless the directory stack is	empty.
	      Arguments, if supplied, have the following meanings:
	      -n     Suppresses	the normal change of directory	when  rotating
		     or	 adding	 directories  to  the  stack, so that only the
		     stack is manipulated.
	      +n     Rotates the stack so that	the  nth  directory  (counting
		     from  the	left  of the list shown	by 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 as if it had been supplied
		     as	the argument to	the cd builtin.

	      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, split into
	      words as described above under Word  Splitting,  and  the	 first
	      word  is assigned	to the first name, the second word to the sec-
	      ond name,	and so on.  If there are more words  than  names,  the
	      remaining	words and their	intervening delimiters are assigned to
	      the last name.  If there are fewer words	read  from  the	 input
	      stream  than  names, the remaining names are assigned empty val-
	      ues.  The	characters in IFS are used  to	split  the  line  into
	      words  using  the	 same  rules the shell uses for	expansion (de-
	      scribed above under Word Splitting).   The  backslash  character
	      (\) may be used to remove	any special meaning for	the next char-
	      acter read and for line  continuation.   Options,	 if  supplied,
	      have the following 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 honors 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.	  The result is	not split on the characters in
		     IFS; the intent is	that the variable is assigned  exactly
		     the characters read (with the exception of	backslash; see
		     the -r option below).
	      -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  (or a specified number of	characters) is
		     not read within timeout seconds.  timeout may be a	 deci-
		     mal  number with a	fractional portion following the deci-
		     mal point.	 This option is	 only  effective  if  read  is
		     reading  input  from  a  terminal,	pipe, or other special
		     file; it has no effect when reading from  regular	files.
		     If	read times out,	read saves any partial input read into
		     the specified variable name.  If timeout is 0,  read  re-
		     turns  immediately, without trying	to read	any data.  The
		     exit status is 0 if input is available on	the  specified
		     file  descriptor, non-zero	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	exit status is zero, unless end-of-file	is en-
	      countered, read times out	(in which case the status  is  greater
	      than  128),  a variable assignment error (such as	assigning to a
	      readonly variable) occurs, or an invalid file descriptor is sup-
	      plied 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 stop executing and return the value	speci-
	      fied by n	to its caller.	If n is	omitted, the return status  is
	      that  of the last	command	executed in the	function body.	If re-
	      turn is executed by a trap handler, the last command used	to de-
	      termine  the status is the last command executed before the trap
	      handler.	if return is executed during a DEBUG  trap,  the  last
	      command  used  to	 determine the status is the last command exe-
	      cuted by the trap	handler	before return was invoked.  If	return
	      is  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 n is supplied, the return value is its least signif-
	      icant 8 bits.  The return	status is non-zero if return  is  sup-
	      plied  a non-numeric argument, or	is used	outside	a function and
	      not during execution of a	script by . or	source.	  Any  command
	      associated with the RETURN trap is executed before execution re-
	      sumes 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      Each variable or function	that is	created	or modified is
		      given the	export attribute and marked 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	list, or  a  compound  command
		      (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 !.	 If  a
		      compound	command	 other	than a subshell	returns	a non-
		      zero status because a command failed while -e was	 being
		      ignored,	the  shell  does  not exit.  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.

		      If a compound command or shell function  executes	 in  a
		      context  where -e	is being ignored, none of the commands
		      executed within the compound command  or	function  body
		      will  be	affected  by the -e setting, even if -e	is set
		      and a command returns a failure status.  If  a  compound
		      command  or  shell function sets -e while	executing in a
		      context where -e is ignored, that	setting	will not  have
		      any  effect  until  the  compound	command	or the command
		      containing the function call completes.
	      -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).  All processes run
		      in a separate process group.  When a background job com-
		      pletes, the shell	prints a line containing its exit sta-
		      tus.
	      -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).	See  SEE  ALSO
			      below for	a reference to a document that details
			      how posix	mode affects bash's behavior.
		      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 resolve 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 settings controlling	optional shell	behav-
	      ior.   The settings can be either	those listed below, or,	if the
	      -o option	is used, those available with the -o option to the set
	      builtin command.	With no	options, or with the -p	option,	a list
	      of all settable 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 following 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,	 shopt
	      shows  only  those options which are set or unset, respectively.
	      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 filename 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.
	      colonbreakswords
		      If set, and readline is being used, bash will treat : as
		      separating  word	being  completed (see Completing under
		      READLINE above).	This is	enabled	by default.
	      compat31
		      If set, bash changes its behavior	to that	of version 3.1
		      with  respect  to	quoted arguments to the	[[ conditional
		      command's	=~ operator and	locale-specific	string compar-
		      ison when	using the [[ conditional command's < and > op-
		      erators.	Bash versions prior to bash-4.1	use ASCII col-
		      lation and strcmp(3); bash-4.1 and later use the current
		      locale's collation sequence and strcoll(3).
	      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
		      (see  previous  item)  and  the effect of	interrupting a
		      command list.  Bash versions 3.2	and  earlier  continue
		      with  the	 next command in the list after	one terminates
		      due to an	interrupt.
	      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  description	 of compat31) and the effect of	inter-
		      rupting a	command	list.  Bash versions 4.0 and later in-
		      terrupt the list as if the shell received	the interrupt;
		      previous versions	continue with the next command in  the
		      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.
	      compat42
		      If  set, bash does not process the replacement string in
		      the pattern substitution word expansion using quote  re-
		      moval.
	      compat43
		      If  set, bash does not print a warning message if	an at-
		      tempt is made to use a quoted compound array  assignment
		      as  an  argument to declare, makes word expansion	errors
		      non-fatal	errors that cause the current command to  fail
		      (the  default behavior is	to make	them fatal errors that
		      cause the	shell to exit),	and does not  reset  the  loop
		      state  when  a  shell  function is executed (this	allows
		      break or continue	in a shell function to affect loops in
		      the caller's context).
	      complete_fullquote
		      If  set,	bash  quotes all shell metacharacters in file-
		      names and	directory names	 when  performing  completion.
		      If not set, bash removes metacharacters such as the dol-
		      lar sign from the	set of characters that will be	quoted
		      in  completed filenames when these metacharacters	appear
		      in shell variable	references in words to	be  completed.
		      This  means that dollar signs in variable	names that ex-
		      pand to directories will not  be	quoted;	 however,  any
		      dollar  signs appearing in filenames will	not be quoted,
		      either.  This is active only when	bash  is  using	 back-
		      slashes  to quote	completed filenames.  This variable is
		      set by default, which is the default  bash  behavior  in
		      versions through 4.2.
	      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  at shell	invocation, arrange to execute the de-
		      bugger profile before the	shell starts, identical	to the
		      --debugger  option.   If	set after invocation, behavior
		      intended for use by debuggers is enabled:
		      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), the shell
			     simulates a call to return.
		      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.
	      globasciiranges
		      If set,  range  expressions  used	 in  pattern  matching
		      bracket  expressions (see	Pattern	Matching above)	behave
		      as if in the traditional C locale	when  performing  com-
		      parisons.	  That	is, the	current	locale's collating se-
		      quence is	not taken into account,	so b will not  collate
		      between  A  and  B,  and upper-case and lower-case ASCII
		      characters will collate together.
	      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.
	      inherit_errexit
		      If  set,	command	substitution inherits the value	of the
		      errexit option, instead of unsetting it in the  subshell
		      environment.   This option is enabled when posix mode is
		      enabled.
	      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, when performing pattern substi-
		      tution  word expansions, or when filtering possible com-
		      pletions as part of programmable completion.
	      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.  A login shell cannot be suspended; the -f option	can be
	      used to override this and	force the suspension.  The return sta-
	      tus  is  0  unless the shell is a	login shell and	-f is not sup-
	      plied, or	if job control is not enabled.

       test expr
       [ expr ]
	      Return a status of 0 (true) or 1 (false) depending on the	evalu-
	      ation of the conditional expression expr.	 Each operator and op-
	      erand 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
	      pipeline (which may consist of a single simple command), a list,
	      or a compound command returns a non-zero exit status, subject to
	      the following conditions.	 The ERR trap is not executed  if  the
	      failed command is	part of	the command list immediately following
	      a	while or until keyword,	part of	the test in an	if  statement,
	      part of a	command	executed in a && or || list except the command
	      following	the final && or	||, any	command	in a pipeline but  the
	      last,  or	 if the	command's return value is being	inverted using
	      !.  These	are the	same conditions	obeyed by the errexit (-e) op-
	      tion.

	      Signals ignored upon entry to the	shell cannot be	trapped	or re-
	      set.  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,	which is not necessar-
	      ily  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 option is not also	used.  The table of hashed commands is
	      not  consulted  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 [-HSabcdefiklmnpqrstuvxPT	[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
	      -k     The maximum number	of kqueues that	may be allocated
	      -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
	      -P     The maximum number	of pseudoterminals
	      -T     The maximum number	of threads

	      If limit is given, and the -a option is not used,	limit  is  the
	      new  value  of  the  specified resource.	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; -P, -T, -b, -k, -n, and -u, which	are  unscaled  values;
	      and, when	in Posix mode, -c and -f, which	are in 512-byte	incre-
	      ments.  The return status	is 0 unless an invalid option or argu-
	      ment is supplied,	or an error occurs while setting a new limit.

       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] [-n]	[name ...]
	      For each name, remove the	corresponding  variable	 or  function.
	      If the -v	option is given, each name refers to a shell variable,
	      and that variable	is removed.  Read-only variables  may  not  be
	      unset.   If  -f  is specified, each name refers to a shell func-
	      tion, and	the function definition	is removed.  If	the -n	option
	      is  supplied, and	name is	a variable with	the nameref attribute,
	      name will	be unset rather	than the variable it  references.   -n
	      has  no  effect if the -f	option is supplied.  If	no options are
	      supplied,	each name refers to a variable;	if there is  no	 vari-
	      able  by	that name, any function	with that name is unset.  Each
	      unset variable or	 function  is  removed	from  the  environment
	      passed  to subsequent commands.  If any of COMP_WORDBREAKS, RAN-
	      DOM, SECONDS, LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are
	      unset, they lose their special properties, even if they are sub-
	      sequently	reset.	The exit status	is true	unless a name is read-
	      only.

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

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  filename  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 --
	      http://pubs.opengroup.org/onlinepubs/9699919799/
       http://tiswww.case.edu/~chet/bash/POSIX -- a description	of posix mode
       sh(1), ksh(1), csh(1)
       emacs(1), vi(1)
       readline(3)

FILES
       /usr/local/bin/bash
	      The bash executable
       /etc/profile
	      The systemwide initialization file, executed for login shells
       ~/.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	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

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

       Comments	and bug	reports	concerning this	manual page should be directed
       to 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 4.4			2016 August 26			       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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