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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) 1989-2018 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, including -o, can be	used as	 options  when
       the  shell  is invoked.	In addition, bash interprets the following op-
       tions 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	or when	reading	 input
		 through a pipe.
       -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  /usr/lo-
	      cal/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 INVO-
	      CATION below).

       --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 /usr/local/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	/usr/local/etc/profile
       and ~/.profile, in that order.  The --noprofile option may be  used  to
       inhibit	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).  See COMMAND EXECUTION ENVIRONMENT	for a description of a
       subshell	environment.  If the lastpipe  option  is  enabled  using  the
       shopt builtin (see the description of shopt below), the last element of
       a pipeline may be run by	the shell process.

   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.  These  are
       referred	 to  as	 asynchronous commands.	 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 exe-
       cuted.

       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 (success).

       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 a POSIX extended regular ex-
	      pression	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	condi-
	      tional 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 expressions in regular expressions must be treated care-
	      fully,  since  normal quoting characters lose their meanings be-
	      tween 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	subex-
	      pressions	 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 expres-
	      sion.  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 matching rules  described	 under
	      Pattern Matching below.  The word	is expanded using tilde	expan-
	      sion, parameter and variable  expansion,	arithmetic  expansion,
	      command  substitution,  process  substitution and	quote removal.
	      Each pattern examined is expanded	using tilde expansion, parame-
	      ter  and	variable expansion, arithmetic expansion, command sub-
	      stitution, 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  cor-
	      responding  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  patterns.	Using  ;;&  in
	      place  of	 ;;  causes the	shell to test the next pattern list in
	      the statement, if	any, and execute any associated	list on	a suc-
	      cessful  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.  Other than	those  created
       to  execute command and process substitutions, 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 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)
	      \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$2c...", where c
	      is the first character of	the value of the IFS variable.	If IFS
	      is  unset,  the  parameters  are separated by spaces.  If	IFS is
	      null, the	parameters are joined without intervening separators.
       @      Expands to the positional	parameters,  starting  from  one.   In
	      contexts	where  word  splitting is performed, this expands each
	      positional parameter to a	separate word; if  not	within	double
	      quotes,  these words are subject to word splitting.  In contexts
	      where word splitting is not performed, this expands to a	single
	      word  with each positional parameter separated by	a space.  When
	      the expansion occurs within double quotes,  each	parameter  ex-
	      pands  to	 a separate word.  That	is, "$@" 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	 simple	 command executed in the fore-
	      ground, after expansion.	Also set to the	full pathname used  to
	      invoke  each  command executed and placed	in the environment ex-
	      ported to	that command.	When  checking	mail,  this  parameter
	      holds the	name of	the mail file currently	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.   Assignments  to
	      BASHPID  have no effect.	If BASHPID is unset, it	loses its spe-
	      cial properties, even if it is subsequently reset.
       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).	 Setting  extdebug  after  the
	      shell has	started	to execute a script, or	referencing this vari-
	      able when	extdebug is not	set, may result	in  inconsistent  val-
	      ues.
       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).  Setting extdebug after the	shell has started to execute a
	      script,  or  referencing this variable when extdebug is not set,
	      may result in inconsistent values.
       BASH_ARGV0
	      When referenced, this variable expands to	the name of the	 shell
	      or shell script (identical to $0;	see the	description of special
	      parameter	0 above).  Assignment to BASH_ARGV0 causes  the	 value
	      assigned	to also	be assigned to $0.  If BASH_ARGV0 is unset, it
	      loses its	special	properties, even if it is subsequently reset.
       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.
       EPOCHREALTIME
	      Each time	this parameter is referenced, it expands to the	number
	      of  seconds  since  the  Unix  Epoch (see	time(3)) as a floating
	      point  value  with  micro-second	granularity.   Assignments  to
	      EPOCHREALTIME  are ignored.  If EPOCHREALTIME is unset, it loses
	      its special properties, even if it is subsequently reset.
       EPOCHSECONDS
	      Each time	this parameter is referenced, it expands to the	number
	      of  seconds  since the Unix Epoch	(see time(3)).	Assignments to
	      EPOCHSECONDS are ignored.	 If EPOCHSECONDS is  unset,  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  file
	      names  to	 be  ignored  by  pathname  expansion.	If a file name
	      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).
       INSIDE_EMACS
	      If this variable appears	in  the	 environment  when  the	 shell
	      starts,  bash  assumes  that it is running inside	an Emacs shell
	      buffer and may disable line editing, depending on	the  value  of
	      TERM.
       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.	 When the shell	enters
	      posix mode, it sets this variable	if it was not already set.
       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 the expanded value	of PS4
	      is replicated multiple times, as necessary, to indicate multiple
	      levels of	indirection.  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, for	both indexed and asso-
       ciative arrays.	Negative subscripts to indexed arrays are  interpreted
       as  described  above.   Unsetting the last element of an	array variable
       does not	unset the variable.  unset name, where name is	an  array,  or
       unset  name[subscript],	where  subscript is * or @, removes the	entire
       array.

       When using a variable name with a subscript as an argument  to  a  com-
       mand,  such  as with unset, without using the word expansion syntax de-
       scribed above, the argument is subject to pathname expansion.  If path-
       name expansion is not desired, the argument should be quoted.

       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 in-
       crease the number of words of the expansion; other expansions expand  a
       single  word to a single	word.  The only	exceptions to this are the ex-
       pansions	 of  "$@"  and	"${name[@]}",  and,  in	 most  cases,  $*  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, and
       inhibits	brace expansion	until the closing }.

       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.

       Bash  also  performs tilde expansion on words satisfying	the conditions
       of variable assignments (as described above under PARAMETERS) when they
       appear  as arguments to simple commands.	 Bash does not do this,	except
       for the declaration commands listed above, when in posix	mode.

   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 indirection.  Bash
       uses the	value formed by	expanding the rest of parameter	as the new pa-
       rameter;	 this  is  then	expanded and that value	is used	in the rest of
       the expansion, rather than the expansion	 of  the  original  parameter.
       This is known as	indirect expansion.  The value is subject to tilde ex-
       pansion,	parameter expansion, command substitution, and arithmetic  ex-
       pansion.	  If  parameter	 is a nameref, this expands to the name	of the
       parameter referenced by parameter instead of  performing	 the  complete
       indirect	 expansion.   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 indirec-
       tion.

       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, and matched against the
	      expanded value of	parameter using	the rules described under Pat-
	      tern  Matching  below.   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	 pattern  (the	``##''
	      case)  deleted.  If parameter is @ or *, the pattern removal op-
	      eration is applied to each positional parameter in turn, and the
	      expansion	is the resultant list.	If parameter is	an array vari-
	      able 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, and matched against the
	      expanded value of	parameter using	the rules described under Pat-
	      tern  Matching below.  If	the pattern matches a trailing portion
	      of the expanded value of parameter, then the result of  the  ex-
	      pansion  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/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.	The match is performed using the rules described under
	      Pattern Matching below.  If pattern begins with /,  all  matches
	      of  pattern  are	replaced with string.  Normally	only the first
	      match is replaced.  If pattern begins with #, it must  match  at
	      the  beginning  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 /	following 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 parame-
	      ter in turn, and the expansion is	the resultant list.  If	param-
	      eter is an array variable	subscripted with @ or *, the substitu-
	      tion 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 mechanism.
	      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 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.  The filenames ``.''  and ``..''  must al-
       ways  be	 matched  explicitly, even if dotglob is set.  In other	cases,
       the ``.''  character is not treated specially.  When matching  a	 path-
       name,  the slash	character must always be matched explicitly by a slash
       in the pattern, but in other matching contexts it can be	matched	 by  a
       special	pattern	 character  as described below under Pattern Matching.
       See the description of shopt below under	SHELL BUILTIN COMMANDS	for  a
       description  of	the  nocaseglob, nullglob, failglob, and dotglob shell
       options.

       The GLOBIGNORE shell variable may be used to restrict the set  of  file
       names  matching	a  pattern.   If GLOBIGNORE is set, each matching file
       name that also matches one of the patterns  in  GLOBIGNORE  is  removed
       from  the list of matches.  If the nocaseglob option is set, the	match-
       ing against the patterns	in GLOBIGNORE is performed without  regard  to
       case.  The filenames ``.''  and ``..''  are always ignored when GLOBIG-
       NORE 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 beginning 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

       Complicated extended pattern matching against long strings is slow, es-
       pecially	when the patterns contain alternations and the strings contain
       multiple	matches.  Using	separate matches against shorter  strings,  or
       using arrays of strings instead of a single long	string,	may be faster.

   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.  If {varname} is supplied,	the  redirect-
       ion  persists  beyond the scope of the command, allowing	the shell pro-
       grammer to manage the file descriptor himself.

       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 tilde expansion, parameter and variable expansion,
       command substitution, arithmetic	expansion, and quote  removal.	 Path-
       name  expansion	and  word  splitting are not performed.	 The result is
       supplied	as a single string, with a newline appended, 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, and
       all lines that make up a	compound command, before executing any of  the
       commands	 on  that  line	or the compound	command.  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.  If a variable is declared local, the vari-
       able's visible scope is restricted to that function  and	 its  children
       (including the functions	it calls).  Local variables "shadow" variables
       with the	same name declared at previous scopes.	For instance, a	 local
       variable	 declared  in  a  function hides a global variable of the same
       name: references	and assignments	refer to the local  variable,  leaving
       the  global variable unmodified.	 When the function returns, the	global
       variable	is once	again visible.

       The shell uses dynamic  scoping	to  control  a	variable's  visibility
       within  functions.   With  dynamic scoping, visible variables and their
       values are a result of the sequence of function calls that caused  exe-
       cution  to  reach the current function.	The value of a variable	that a
       function	sees depends on	its value within its caller, if	 any,  whether
       that  caller  is	the "global" scope or another shell function.  This is
       also the	value that a local variable  declaration  "shadows",  and  the
       value that is restored when the function	returns.

       For  example, if	a variable var is declared as local in function	func1,
       and func1 calls another function	func2, references  to  var  made  from
       within func2 will resolve to the	local variable var from	func1, shadow-
       ing any global variable named var.

       The unset builtin also acts using the same dynamic scope: if a variable
       is local	to the current scope, unset will unset it; otherwise the unset
       will refer to the variable found	in  any	 calling  scope	 as  described
       above.	If a variable at the current local scope is unset, it will re-
       main so until it	is reset in that scope or until	the function  returns.
       Once  the  function returns, any	instance of the	variable at a previous
       scope will become visible.  If the unset	acts on	a variable at a	previ-
       ous  scope,  any	 instance  of  a variable with that name that had been
       shadowed	will become visible.

       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.

       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
       - +    unary minus and plus
       ++id --id
	      variable pre-increment and pre-decrement
       ! ~    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.  The	test abd [  commands  determine	 their
       behavior	 based	on  the	 number	 of arguments; see the descriptions of
       those commands for any other command-specific actions.

       Expressions are formed from the following unary	or  binary  primaries.
       Bash  handles several filenames specially when they are used in expres-
       sions.  If the operating	system on which	bash is	running	provides these
       special	files,	bash will use them; otherwise it will emulate them in-
       ternally	with this behavior: If any file	argument to one	 of  the  pri-
       maries is of the	form /dev/fd/n,	then file descriptor n is checked.  If
       the file	argument to  one  of  the  primaries  is  one  of  /dev/stdin,
       /dev/stdout,  or	/dev/stderr, file descriptor 0,	1, or 2, respectively,
       is checked.

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

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

       -a file
	      True if file exists.
       -b file
	      True if file exists and is a block special file.
       -c file
	      True if file exists and is a character special file.
       -d file
	      True if file exists and is a directory.
       -e file
	      True if file exists.
       -f file
	      True if file exists and is a regular file.
       -g file
	      True if file exists and is set-group-id.
       -h file
	      True if file exists and is a symbolic link.
       -k file
	      True if file exists and its ``sticky'' bit is set.
       -p file
	      True if file exists and is a named pipe (FIFO).
       -r file
	      True if file exists and is readable.
       -s file
	      True if file exists and has a size greater than zero.
       -t fd  True if file descriptor fd is open and refers to a terminal.
       -u file
	      True if file exists and its set-user-id bit is set.
       -w file
	      True if file exists and is writable.
       -x file
	      True if file exists and is executable.
       -G file
	      True if file exists and is owned by the effective	group id.
       -L file
	      True if file exists and is a symbolic link.
       -N file
	      True  if	file  exists  and  has been modified since it was last
	      read.
       -O file
	      True if file exists and is owned by the effective	user id.
       -S file
	      True if file exists and is a socket.
       file1 -ef file2
	      True if file1 and	file2 refer to the same	device and inode  num-
	      bers.
       file1 -nt file2
	      True  if	file1  is  newer (according to modification date) than
	      file2, or	if file1 exists	and file2 does not.
       file1 -ot file2
	      True if file1 is older than file2, or if file2 exists and	 file1
	      does not.
       -o optname
	      True  if	the  shell option optname is enabled.  See the list of
	      options under the	description  of	 the  -o  option  to  the  set
	      builtin below.
       -v varname
	      True  if	the shell variable varname is set (has been assigned a
	      value).
       -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.  When used with the	[[ command,  Arg1  and
	      Arg2  are	 evaluated  as arithmetic expressions  (see ARITHMETIC
	      EVALUATION above).

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
       in  a  separate execution environment with the original command and the
       original	command's arguments as its arguments, and the function's  exit
       status  becomes	the exit status	of that	subshell.  If that function is
       not defined, the	shell prints an	error message and returns an exit sta-
       tus 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.

       When  the shell is waiting for a	job or process using the wait builtin,
       and job control is enabled, wait	 will  return  when  the  job  changes
       state.  The  -f option will force wait to wait until the	job or process
       terminates before returning.

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 displays PS4	as de-
       scribed above before tracing each command when the  -x  option  is  en-
       abled.	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.
       emacs-mode-string (@)
	      If  the  show-mode-in-prompt variable is enabled,	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 control sequence into the
	      mode string.
       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.
       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 string to the beginning of the prompt indi-
	      cating the editing mode: emacs, vi  command,  or	vi  insertion.
	      The mode strings are user-settable (e.g.,	emacs-mode-string).
       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))
	      If the show-mode-in-prompt variable is enabled, 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 sequences of non-
	      printing characters, which can be	used to	embed a	terminal  con-
	      trol sequence into the mode string.
       vi-ins-mode-string ((ins))
	      If  the  show-mode-in-prompt variable is enabled,	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  sequences  of  non-
	      printing	characters, which can be used to embed a terminal con-
	      trol 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, after any comparison operator,
	       extends	to  the	 end  of  the line; unless otherwise noted, 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.

	      version
		     The  version  test	 may  be  used	to perform comparisons
		     against specific readline versions.  The version  expands
		     to	 the  current readline version.	 The set of comparison
		     operators includes	=, (and	==), !=, <=,  >=,  <,  and  >.
		     The  version number supplied on the right side of the op-
		     erator consists of	a major	version	 number,  an  optional
		     decimal point, and	an optional minor version (e.g., 7.1).
		     If	the minor version is omitted, it is assumed to	be  0.
		     The operator may be separated from	the string version and
		     from the version number argument by whitespace.

	      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

	      variable
		     The variable construct provides simple equality tests for
		     readline variables	and values.  The permitted  comparison
		     operators	are  =,	==, and	!=.  The variable name must be
		     separated from the	comparison operator by whitespace; the
		     operator  may  be	separated  from	the value on the right
		     hand side by whitespace.  Both string and	boolean	 vari-
		     ables  may	 be  tested.  Boolean variables	must be	tested
		     against the values	on and off.

       $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.
       previous-screen-line
	      Attempt  to move point to	the same physical screen column	on the
	      previous physical	screen line. This will not  have  the  desired
	      effect  if  the current Readline line does not take up more than
	      one physical line	or if point is not greater than	the length  of
	      the prompt plus the screen width.
       next-screen-line
	      Attempt  to move point to	the same physical screen column	on the
	      next physical screen line. This will not have the	desired	effect
	      if  the  current	Readline  line	does not take up more than one
	      physical line or if the length of	the current Readline  line  is
	      not greater than the length of the prompt	plus the screen	width.
       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.
       history-substring-search-backward
	      Search backward through the history for the string of characters
	      between the start	of the current line and	the current cursor po-
	      sition (the point).  The search string may match anywhere	 in  a
	      history line.  This is a non-incremental search.
       history-substring-search-forward
	      Search  forward through the history for the string of characters
	      between the start	of the current line and	the point.  The	search
	      string  may match	anywhere in a history line.  This is a non-in-
	      cremental	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.  A
	      numeric argument,	if supplied, specifies the  history  entry  to
	      use instead of the current line.
       edit-and-execute-command	(C-x C-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-lowercase-version (M-A, M-B, M-x, ...)
	      If  the  metafied	character x is uppercase, run the command that
	      is bound to the corresponding metafied lowercase character.  The
	      behavior is undefined if x is already lowercase.
       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.  If there	is  no
       default	compspec, bash attempts	alias expansion	on the command word as
       a final resort, and attempts to find a compspec for  the	 command  word
       from any	successful expansion.

       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 fol-
       lowing 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, and is performed on each
       line individually without taking	quoting	on  previous  lines  into  ac-
       count.	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	avail-
       able to manipulate the selected words.  The line	is broken  into	 words
       in  the same fashion as when reading input, so that several metacharac-
       ter-separated words surrounded by quotes	are considered one word.  His-
       tory  expansions	are introduced by the appearance of the	history	expan-
       sion character, which is	! by default.  Only backslash (\)  and	single
       quotes  can  quote the history expansion	character, but the history ex-
       pansion character is also treated as quoted if it immediately  precedes
       the closing double quote	in a double-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] [-DEI] [-A action] [-G glob-
       pat] [-W	wordlist] [-F function]	[-C command]
	      [-X filterpat] [-P prefix] [-S suffix] name [name	...]
       complete	-pr [-DEI] [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 other sup-
	      plied 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  other supplied options and actions should apply
	      to ``empty'' command completion; that is,	 completion  attempted
	      on  a  blank  line.  The -I option indicates that	other supplied
	      options and actions should apply to  completion  on  the	inital
	      non-assignment  word  on	the line, or after a command delimiter
	      such as ;	or |, which is usually command	name  completion.   If
	      multiple	options	 are  supplied,	the -D option takes precedence
	      over -E, and both	take precedence	over -I.  If any of -D,	-E, or
	      -I  are  supplied,  any  other name arguments are	ignored; these
	      completions only apply to	the case specified by the option.

	      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.  Shell quoting is honored within  wordlist,
		      in order to provide a mechanism for the words to contain
		      shell metacharacters or characters in the	value of  IFS.
		      The  possible  completions are the members of the	resul-
		      tant list	which match the	word being completed.
	      -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] [-DEI] [+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 other supplied  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 other
	      supplied options should apply to ``empty''  command  completion;
	      that  is,	 completion  attempted on a blank line.	 The -I	option
	      indicates	that other supplied options should apply to completion
	      on  the  inital non-assignment word on the line, or after	a com-
	      mand delimiter such as ; or |, which  is	usually	 command  name
	      completion.

	      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 and +A may not be used to destroy array
	      variables	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
	      variable	name  is followed by =value, the value of the variable
	      is set to	value.	When using -a or -A and	the  compound  assign-
	      ment  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.  A subshell exits unconditionally if
	      exec fails.  If command is not specified,	any redirections  take
	      effect  in  the  current	shell, and the return status is	0.  If
	      there is a redirection error, the	return status is 1.

       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 interpreted 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 -d start-end
       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.   If	offset
		     is	negative, it is	interpreted as relative	to one greater
		     than the last history position, so	negative indices count
		     back  from	 the  end  of  the history, and	an index of -1
		     refers to the current history -d command.
	      -d start-end
		     Delete the	history	entries	between	 positions  start  and
		     end,  inclusive.	Positive and negative values for start
		     and end are interpreted as	described above.
	      -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.	 If delim is the empty
		     string, mapfile will terminate a line when	it reads a NUL
		     character.
	      -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.	 If delim is the empty
		     string, read will terminate a line	when it	 reads	a  NUL
		     character.
	      -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, but  uses	 Read-
		     line's default filename completion.
	      -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 then 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; if optnames are supplied, the	output
	      is  restricted to	those options.	The -p option causes output to
	      be displayed in a	form that may be reused	as input.   Other  op-
	      tions 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:

	      assoc_expand_once
		      If set, the shell	suppresses multiple evaluation of  as-
		      sociative	 array subscripts during arithmetic expression
		      evaluation, while	executing builtins  that  can  perform
		      variable	assignments, and while executing builtins that
		      perform array dereferencing.
	      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  external
		      (non-builtin)  command  and,  if	necessary, updates the
		      values of	LINES and COLUMNS.  This option	is enabled  by
		      default.
	      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.	This option is
		      enabled by default, but only has an  effect  if  command
		      history is enabled, as described above under HISTORY.
	      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).
	      compat44
		      If  set,	bash  saves  the  positional   parameters   to
		      BASH_ARGV	and BASH_ARGC before they are used, regardless
		      of whether or not	extended debugging mode	is enabled.
	      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.  The filenames ``.''
		      and ``..''  must always be matched explicitly,  even  if
		      dotglob is set.
	      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.
	      localvar_inherit
		      If set, local variables inherit the value	and attributes
		      of a variable of the same	name that exists at a previous
		      scope before any new value is assigned.  The nameref at-
		      tribute is not inherited.
	      localvar_unset
		      If  set,	calling	 unset	on local variables in previous
		      function scopes marks them so  subsequent	 lookups  find
		      them  unset until	that function returns. This is identi-
		      cal to the behavior of unsetting local variables at  the
		      current function scope.
	      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.
	      progcomp_alias
		      If set, and programmable	completion  is	enabled,  bash
		      treats  a	command	name that doesn't have any completions
		      as a possible alias and attempts alias expansion.	If  it
		      has  an alias, bash attempts programmable	completion us-
		      ing the command word resulting from the expanded alias.
	      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 [-fn] [id ...]
	      Wait for each specified child process and	return its termination
	      status.  Each id 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 id 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 the	-f option is supplied, and job
	      control is enabled, wait forces id to terminate before returning
	      its  status, instead of returning	when it	changes	status.	 If id
	      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
       /usr/local/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 5.0			2018 December 7			       BASH(1)

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