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BASH(1)			    General Commands Manual		       BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2009 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
       In addition to the single-character shell options documented in the de-
       scription of the	set builtin command, bash interprets the following op-
       tions when it is	invoked:

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

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

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

       --login
	      Equivalent to -l.

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

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

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

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

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

       --verbose
	      Equivalent to  -v.

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

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

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

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

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

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

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

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

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

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

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

       Bash attempts to	determine when it is being run with its	standard input
       connected to a a	network	connection, as if by the remote	shell  daemon,
       usually	rshd,  or the secure shell daemon sshd.	 If bash determines it
       is being	run in this fashion,  it  reads	 and  executes	commands  from
       ~/.bashrc, if that file exists and is readable.	It will	not do this if
       invoked as sh.  The --norc option may be	used to	inhibit	this behavior,
       and  the	 --rcfile option may be	used to	force another file to be read,
       but rshd	does not generally invoke the shell with those options or  al-
       low them	to be specified.

       If the shell is started with the	effective user (group) id not equal to
       the real	user (group) id, and the -p option is not supplied, no startup
       files are read, shell functions are not inherited from the environment,
       the SHELLOPTS, BASHOPTS,	CDPATH,	and GLOBIGNORE variables, if they  ap-
       pear  in	the environment, are ignored, and the effective	user id	is set
       to the real user	id.  If	the -p option is supplied at  invocation,  the
       startup behavior	is the same, but the effective user id is not reset.

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

RESERVED WORDS
       Reserved	words are words	that have a special meaning to the shell.  The
       following words are recognized as reserved when unquoted	and either the
       first  word  of a simple	command	(see SHELL GRAMMAR below) or the third
       word of a case or for command:

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

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

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

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

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

       The  standard output of command is connected via	a pipe to the standard
       input of	command2.  This	connection is performed	 before	 any  redirec-
       tions specified by the command (see REDIRECTION below).	If |& is used,
       the standard error of command is	connected to command2's	standard input
       through	the pipe; it is	shorthand for 2>&1 |.  This implicit redirect-
       ion of the standard error is performed after any	redirections specified
       by the command.

       The return status of a pipeline is the exit status of the last command,
       unless the pipefail option is enabled.  If  pipefail  is	 enabled,  the
       pipeline's  return  status is the value of the last (rightmost) command
       to exit with a non-zero status, or zero if all commands	exit  success-
       fully.  If the reserved word !  precedes	a pipeline, the	exit status of
       that pipeline is	the logical negation of	the exit status	 as  described
       above.	The  shell waits for all commands in the pipeline to terminate
       before returning	a value.

       If the time reserved word precedes a pipeline, the elapsed as  well  as
       user  and  system  time consumed	by its execution are reported when the
       pipeline	terminates.  The -p option changes the output format  to  that
       specified  by  POSIX.   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.

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

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

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

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

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

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

	      command1 && command2

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

       An OR list has the form

	      command1 || command2

       command2	is executed if and only	if command1 returns  a	non-zero  exit
       status.	 The  return  status of	AND and	OR lists is the	exit status of
       the last	command	executed in the	list.

   Compound Commands
       A compound command is one of the	following:

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

       { list; }
	      list is simply executed in the current shell environment.	  list
	      must  be	terminated with	a newline or semicolon.	 This is known
	      as a group command.  The return status is	 the  exit  status  of
	      list.   Note that	unlike the metacharacters ( and	), { and } are
	      reserved words and must occur where a reserved word is permitted
	      to  be  recognized.   Since they do not cause a word break, they
	      must be separated	from  list  by	whitespace  or	another	 shell
	      metacharacter.

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

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

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

	      When  the	 == and	!= operators are used, the string to the right
	      of the operator is considered a pattern and matched according to
	      the  rules described below under Pattern Matching.  If the shell
	      option nocasematch is enabled, the match	is  performed  without
	      regard  to  the case of alphabetic characters.  The return value
	      is 0 if the string matches (==) or does not match	(!=) the  pat-
	      tern, and	1 otherwise.  Any part of the pattern may be quoted to
	      force it to be matched as	a string.

	      An additional binary operator, =~, is available, with  the  same
	      precedence  as  ==  and  !=.  When it is used, the string	to the
	      right of the operator is considered an extended regular  expres-
	      sion and matched accordingly (as in regex(3)).  The return value
	      is 0 if the string matches the pattern, and 1 otherwise.	If the
	      regular  expression  is syntactically incorrect, the conditional
	      expression's return value	is 2.  If the shell option nocasematch
	      is enabled, the match is performed without regard	to the case of
	      alphabetic characters.  Any part of the pattern may be quoted to
	      force  it	 to  be	 matched  as  a	string.	 Substrings matched by
	      parenthesized subexpressions within the regular  expression  are
	      saved  in	 the  array  variable  BASH_REMATCH.   The  element of
	      BASH_REMATCH with	index 0	is the portion of the string  matching
	      the entire regular expression.  The element of BASH_REMATCH with
	      index n is the portion of	the string matching the	nth  parenthe-
	      sized subexpression.

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

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

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

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

       for (( expr1 ; expr2 ; expr3 )) ; do list ; done
	      First, the arithmetic expression expr1 is	evaluated according to
	      the  rules  described  below  under  ARITHMETIC EVALUATION.  The
	      arithmetic expression expr2 is then evaluated  repeatedly	 until
	      it  evaluates  to	zero.  Each time expr2 evaluates to a non-zero
	      value, list is executed and the arithmetic expression  expr3  is
	      evaluated.   If  any  expression is omitted, it behaves as if it
	      evaluates	to 1.  The return value	is the exit status of the last
	      command in list that is executed,	or false if any	of the expres-
	      sions is invalid.

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

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

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

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

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

       The format for a	coprocess is:

	      coproc [NAME] command [redirections]

       This creates a coprocess	named NAME.  If	NAME is	not supplied, the  de-
       fault name is COPROC.  NAME must	not be supplied	if command is a	simple
       command (see above); otherwise, it is interpreted as the	first word  of
       the  simple command.  When the coproc is	executed, the shell creates an
       array variable (see Arrays below) named NAME in the context of the exe-
       cuting  shell.	The standard output of command is connected via	a pipe
       to a file descriptor in the executing shell, and	that  file  descriptor
       is assigned to NAME[0].	The standard input of command is connected via
       a pipe to a file	descriptor in the executing shell, and that  file  de-
       scriptor	 is  assigned to NAME[1].  This	pipe is	established before any
       redirections specified by the command  (see  REDIRECTION	 below).   The
       file  descriptors  can  be  utilized as arguments to shell commands and
       redirections using standard word	expansions.  The  process  id  of  the
       shell spawned to	execute	the coprocess is available as the value	of the
       variable	NAME_PID.  The wait builtin command may	be used	 to  wait  for
       the coprocess to	terminate.

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

   Shell Function Definitions
       A  shell	function is an object that is called like a simple command and
       executes	a compound command with	a new set  of  positional  parameters.
       Shell functions are declared as follows:

       [ function ] name () compound-command [redirection]
	      This  defines a function named name.  The	reserved word function
	      is optional.  If the function reserved  word  is	supplied,  the
	      parentheses  are optional.  The body of the function is the com-
	      pound command compound-command (see  Compound  Commands  above).
	      That  command is usually a list of commands between { and	}, but
	      may be any command listed	under Compound Commands	 above.	  com-
	      pound-command is executed	whenever name is specified as the name
	      of a simple command.  Any	redirections (see  REDIRECTION	below)
	      specified	 when  a  function  is	defined	are performed when the
	      function is executed.  The exit status of	a function  definition
	      is zero unless a syntax error occurs or a	readonly function with
	      the same name already exists.  When executed, the	exit status of
	      a	 function  is  the exit	status of the last command executed in
	      the body.	 (See FUNCTIONS	below.)

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

QUOTING
       Quoting is used to remove the special meaning of	certain	characters  or
       words  to  the shell.  Quoting can be used to disable special treatment
       for special characters, to prevent reserved words from being recognized
       as such,	and to prevent parameter expansion.

       Each  of	 the metacharacters listed above under DEFINITIONS has special
       meaning to the shell and	must be	quoted if it is	to represent itself.

       When the	command	history	expansion facilities are being used (see  HIS-
       TORY EXPANSION below), the history expansion character, usually !, must
       be quoted to prevent history expansion.

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

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

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

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

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

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

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

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

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

       A parameter is set if it	has been assigned a value.  The	null string is
       a valid value.  Once a variable is set, it may be unset only  by	 using
       the unset builtin command (see SHELL BUILTIN COMMANDS below).

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

	      name=[value]

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

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

   Positional Parameters
       A  positional  parameter	 is a parameter	denoted	by one or more digits,
       other than the single digit 0.  Positional parameters are assigned from
       the  shell's  arguments when it is invoked, and may be reassigned using
       the set builtin command.	 Positional parameters may not be assigned  to
       with  assignment	statements.  The positional parameters are temporarily
       replaced	when a shell function is executed (see FUNCTIONS below).

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

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

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands to the full file name used to invoke  this  instance  of
	      bash.
       BASHOPTS
	      A	 colon-separated  list of enabled shell	options.  Each word in
	      the list is a valid argument for the  -s	option	to  the	 shopt
	      builtin command (see SHELL BUILTIN COMMANDS below).  The options
	      appearing	in BASHOPTS are	those reported as  on  by  shopt.   If
	      this  variable  is  in the environment when bash starts up, each
	      shell option in the list will  be	 enabled  before  reading  any
	      startup files.  This variable is read-only.
       BASHPID
	      Expands  to  the	process	 id of the current bash	process.  This
	      differs from $$ under certain circumstances, such	 as  subshells
	      that do not require bash to be re-initialized.
       BASH_ALIASES
	      An  associative  array  variable whose members correspond	to the
	      internal list of aliases as maintained by	the alias builtin Ele-
	      ments  added  to	this array appear in the alias list; unsetting
	      array elements cause aliases to be removed from the alias	list.
       BASH_ARGC
	      An array variable	whose values are the number of	parameters  in
	      each frame of the	current	bash execution call stack.  The	number
	      of parameters to	the  current  subroutine  (shell  function  or
	      script  executed	with  .	or source) is at the top of the	stack.
	      When a subroutine	is executed, the number	of  parameters	passed
	      is pushed	onto BASH_ARGC.	 The shell sets	BASH_ARGC only when in
	      extended debugging mode (see the description of the extdebug op-
	      tion to the shopt	builtin	below)
       BASH_ARGV
	      An  array	 variable containing all of the	parameters in the cur-
	      rent bash	execution call stack.  The final parameter of the last
	      subroutine  call is at the top of	the stack; the first parameter
	      of the initial call is at	the bottom.  When a subroutine is exe-
	      cuted,  the  parameters supplied are pushed onto BASH_ARGV.  The
	      shell sets BASH_ARGV only	when in	extended debugging  mode  (see
	      the  description of the extdebug option to the shopt builtin be-
	      low)
       BASH_CMDS
	      An associative array variable whose members  correspond  to  the
	      internal	hash  table  of	 commands  as  maintained  by the hash
	      builtin.	Elements added to this array appear in the hash	table;
	      unsetting	 array	elements cause commands	to be removed from the
	      hash table.
       BASH_COMMAND
	      The command currently being executed or about  to	 be  executed,
	      unless the shell is executing a command as the result of a trap,
	      in which case it is the command executing	at  the	 time  of  the
	      trap.
       BASH_EXECUTION_STRING
	      The command argument to the -c invocation	option.
       BASH_LINENO
	      An  array	 variable whose	members	are the	line numbers in	source
	      files   corresponding    to    each    member    of    FUNCNAME.
	      ${BASH_LINENO[$i]}  is  the line number in the source file where
	      ${FUNCNAME[$i]} was called (or  ${BASH_LINENO[$i-1]}  if	refer-
	      enced  within another shell function).  The corresponding	source
	      file name	is ${BASH_SOURCE[$i]}.	Use LINENO to obtain the  cur-
	      rent line	number.
       BASH_REMATCH
	      An  array	 variable  whose members are assigned by the =~	binary
	      operator to the [[ conditional command.  The element with	 index
	      0	 is  the portion of the	string matching	the entire regular ex-
	      pression.	 The element with index	n is the portion of the	string
	      matching	the nth	parenthesized subexpression.  This variable is
	      read-only.
       BASH_SOURCE
	      An array variable	whose members are the source filenames	corre-
	      sponding to the elements in the FUNCNAME array variable.
       BASH_SUBSHELL
	      Incremented  by one each time a subshell or subshell environment
	      is spawned.  The initial value is	0.
       BASH_VERSINFO
	      A	readonly array variable	whose members hold version information
	      for  this	 instance  of  bash.  The values assigned to the array
	      members are as follows:
	      BASH_VERSINFO[0]	      The major	version	number (the release).
	      BASH_VERSINFO[1]	      The minor	version	number (the version).
	      BASH_VERSINFO[2]	      The patch	level.
	      BASH_VERSINFO[3]	      The build	version.
	      BASH_VERSINFO[4]	      The release status (e.g.,	beta1).
	      BASH_VERSINFO[5]	      The value	of MACHTYPE.

       BASH_VERSION
	      Expands to a string describing the version of this  instance  of
	      bash.

       COMP_CWORD
	      An  index	 into ${COMP_WORDS} of the word	containing the current
	      cursor position.	This variable is available only	in shell func-
	      tions  invoked  by  the  programmable completion facilities (see
	      Programmable Completion below).

       COMP_KEY
	      The key (or final	key of a key sequence) used to invoke the cur-
	      rent completion function.

       COMP_LINE
	      The  current  command  line.  This variable is available only in
	      shell functions and external commands invoked  by	 the  program-
	      mable completion facilities (see Programmable Completion below).

       COMP_POINT
	      The  index of the	current	cursor position	relative to the	begin-
	      ning of the current command.  If the current cursor position  is
	      at the end of the	current	command, the value of this variable is
	      equal to ${#COMP_LINE}.  This  variable  is  available  only  in
	      shell  functions	and  external commands invoked by the program-
	      mable completion facilities (see Programmable Completion below).

       COMP_TYPE
	      Set to an	integer	value corresponding to the type	of  completion
	      attempted	 that  caused a	completion function to be called: TAB,
	      for normal completion, ?,	for listing completions	after  succes-
	      sive  tabs,  !, for listing alternatives on partial word comple-
	      tion, @, to list completions if the word is not  unmodified,  or
	      %,  for  menu  completion.   This	 variable is available only in
	      shell functions and external commands invoked  by	 the  program-
	      mable completion facilities (see Programmable Completion below).

       COMP_WORDBREAKS
	      The  set	of characters that the readline	library	treats as word
	      separators when performing word completion.  If  COMP_WORDBREAKS
	      is  unset, it loses its special properties, even if it is	subse-
	      quently reset.

       COMP_WORDS
	      An array variable	(see Arrays below) consisting of the  individ-
	      ual  words  in the current command line.	The line is split into
	      words as readline	would split it,	using COMP_WORDBREAKS  as  de-
	      scribed  above.	This variable is available only	in shell func-
	      tions invoked by the  programmable  completion  facilities  (see
	      Programmable Completion below).

       DIRSTACK
	      An array variable	(see Arrays below) containing the current con-
	      tents of the directory stack.  Directories appear	in  the	 stack
	      in  the order they are displayed by the dirs builtin.  Assigning
	      to members of this array variable	may be used to modify directo-
	      ries  already in the stack, but the pushd	and popd builtins must
	      be used to add and remove	directories.  Assignment to this vari-
	      able  will not change the	current	directory.  If DIRSTACK	is un-
	      set, it loses its	special	properties, even if it is subsequently
	      reset.

       EUID   Expands  to  the effective user ID of the	current	user, initial-
	      ized at shell startup.  This variable is readonly.

       FUNCNAME
	      An array variable	containing the names of	 all  shell  functions
	      currently	in the execution call stack.  The element with index 0
	      is the name of any currently-executing shell function.  The bot-
	      tom-most	element	 is  "main".  This variable exists only	when a
	      shell function is	executing.  Assignments	to  FUNCNAME  have  no
	      effect  and  return  an  error status.  If FUNCNAME is unset, it
	      loses its	special	properties, even if it is subsequently reset.

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

       HISTCMD
	      The history number, or index in the history list,	of the current
	      command.	If HISTCMD is unset, it	loses its special  properties,
	      even if it is subsequently reset.

       HOSTNAME
	      Automatically set	to the name of the current host.

       HOSTTYPE
	      Automatically  set  to a string that uniquely describes the type
	      of machine on which bash is executing.  The default  is  system-
	      dependent.

       LINENO Each  time this parameter	is referenced, the shell substitutes a
	      decimal number representing the current sequential  line	number
	      (starting	 with  1)  within a script or function.	 When not in a
	      script or	function, the value substituted	is not	guaranteed  to
	      be meaningful.  If LINENO	is unset, it loses its special proper-
	      ties, even if it is subsequently reset.

       MACHTYPE
	      Automatically set	to a string that fully	describes  the	system
	      type  on	which  bash is executing, in the standard GNU cpu-com-
	      pany-system format.  The default is system-dependent.

       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.

       REPLY  Set  to  the line	of input read by the read builtin command when
	      no arguments are supplied.

       SECONDS
	      Each time	this parameter is referenced, the  number  of  seconds
	      since  shell  invocation is returned.  If	a value	is assigned to
	      SECONDS, the value returned upon subsequent  references  is  the
	      number  of seconds since the assignment plus the value assigned.
	      If SECONDS is unset, it loses its	special	properties, even if it
	      is subsequently reset.

       SHELLOPTS
	      A	 colon-separated  list of enabled shell	options.  Each word in
	      the list is a valid argument  for	 the  -o  option  to  the  set
	      builtin command (see SHELL BUILTIN COMMANDS below).  The options
	      appearing	in SHELLOPTS are those reported	as on by set  -o.   If
	      this  variable  is  in the environment when bash starts up, each
	      shell option in the list will  be	 enabled  before  reading  any
	      startup files.  This variable is read-only.

       SHLVL  Incremented by one each time an instance of bash is started.

       UID    Expands to the user ID of	the current user, initialized at shell
	      startup.	This variable is readonly.

       The following variables are used	by the shell.  In some cases, bash as-
       signs a default value to	a variable; these cases	are noted below.

       BASH_ENV
	      If  this parameter is set	when bash is executing a shell script,
	      its value	is interpreted as a filename  containing  commands  to
	      initialize the shell, as in ~/.bashrc.  The value	of BASH_ENV is
	      subjected	to  parameter  expansion,  command  substitution,  and
	      arithmetic  expansion  before  being interpreted as a file name.
	      PATH is not used to search for the resultant file	name.
       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".
       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.
       COLUMNS
	      Used by the select builtin command  to  determine	 the  terminal
	      width when printing selection lists.  Automatically set upon re-
	      ceipt of a SIGWINCH.
       COMPREPLY
	      An array variable	from which bash	reads the possible completions
	      generated	 by  a shell function invoked by the programmable com-
	      pletion facility (see Programmable Completion below).
       EMACS  If bash finds this variable in the environment  when  the	 shell
	      starts  with  value "t", it assumes that the shell is running in
	      an emacs shell buffer and	disables line editing.
       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:~".
       GLOBIGNORE
	      A	colon-separated	list of	patterns defining the set of filenames
	      to be ignored by pathname	expansion.  If a filename matched by a
	      pathname	expansion  pattern also	matches	one of the patterns in
	      GLOBIGNORE, it is	removed	from the list of matches.
       HISTCONTROL
	      A	colon-separated	list of	values controlling  how	 commands  are
	      saved  on	 the history list.  If the list	of values includes ig-
	      norespace, lines which begin with	 a  space  character  are  not
	      saved  in	 the history list.  A value of ignoredups causes lines
	      matching the previous history entry to not be saved.  A value of
	      ignoreboth is shorthand for ignorespace and ignoredups.  A value
	      of erasedups causes all previous lines matching the current line
	      to  be  removed from the history list before that	line is	saved.
	      Any value	not in the above list is ignored.  If  HISTCONTROL  is
	      unset,  or does not include a valid value, all lines read	by the
	      shell parser are saved on	the history list, subject to the value
	      of  HISTIGNORE.  The second and subsequent lines of a multi-line
	      compound command are not tested, and are added  to  the  history
	      regardless of the	value of HISTCONTROL.
       HISTFILE
	      The name of the file in which command history is saved (see HIS-
	      TORY below).  The	default	value is ~/.bash_history.   If	unset,
	      the  command  history is not saved when an interactive shell ex-
	      its.
       HISTFILESIZE
	      The maximum number of lines contained in the history file.  When
	      this  variable  is  assigned  a value, the history file is trun-
	      cated, if	necessary, by removing the oldest entries, to  contain
	      no  more	than  that number of lines.  The default value is 500.
	      The history file is also truncated to this size after writing it
	      when an interactive shell	exits.
       HISTIGNORE
	      A	 colon-separated list of patterns used to decide which command
	      lines should be saved on the history list.  Each pattern is  an-
	      chored  at the beginning of the line and must match the complete
	      line (no implicit	`*' is	appended).   Each  pattern  is	tested
	      against  the  line after the checks specified by HISTCONTROL are
	      applied.	In addition to the normal shell	pattern	matching char-
	      acters,  `&'  matches the	previous history line.	`&' may	be es-
	      caped using a backslash; the backslash  is  removed  before  at-
	      tempting	a  match.  The second and subsequent lines of a	multi-
	      line compound command are	not tested, and	are added to the  his-
	      tory regardless of the value of HISTIGNORE.
       HISTSIZE
	      The  number  of commands to remember in the command history (see
	      HISTORY below).  The default value is 500.
       HISTTIMEFORMAT
	      If this variable is set and not null, its	value  is  used	 as  a
	      format string for	strftime(3) to print the time stamp associated
	      with each	history	entry displayed	by the	history	 builtin.   If
	      this  variable  is  set,	time stamps are	written	to the history
	      file so they may be preserved across shell sessions.  This  uses
	      the  history  comment  character	to distinguish timestamps from
	      other history lines.
       HOME   The home directory of the	current	user; the default argument for
	      the cd builtin command.  The value of this variable is also used
	      when performing tilde expansion.
       HOSTFILE
	      Contains the name	of a file in the  same	format	as  /etc/hosts
	      that should be read when the shell needs to complete a hostname.
	      The list of possible hostname completions	may be	changed	 while
	      the  shell  is running; the next time hostname completion	is at-
	      tempted after the	value is changed, bash adds  the  contents  of
	      the  new file to the existing list.  If HOSTFILE is set, but has
	      no value,	or does	not name a readable  file,  bash  attempts  to
	      read  /etc/hosts to obtain the list of possible hostname comple-
	      tions.  When HOSTFILE is unset, the hostname list	is cleared.
       IFS    The Internal Field Separator that	is used	for word splitting af-
	      ter  expansion  and  to  split  lines  into  words with the read
	      builtin  command.	  The  default	value  is  ``<space><tab><new-
	      line>''.
       IGNOREEOF
	      Controls the action of an	interactive shell on receipt of	an EOF
	      character	as the sole input.  If set, the	value is the number of
	      consecutive  EOF	characters  which  must	 be typed as the first
	      characters on an input line before bash exits.  If the  variable
	      exists  but  does	not have a numeric value, or has no value, the
	      default value is 10.  If it does not exist,  EOF	signifies  the
	      end of input to the shell.
       INPUTRC
	      The  filename  for the readline startup file, overriding the de-
	      fault of ~/.inputrc (see READLINE	below).
       LANG   Used to determine	the  locale  category  for  any	 category  not
	      specifically selected with a variable starting with LC_.
       LC_ALL This  variable  overrides	 the  value  of	LANG and any other LC_
	      variable specifying a locale category.
       LC_COLLATE
	      This variable determines the collation order used	 when  sorting
	      the  results  of pathname	expansion, and determines the behavior
	      of range expressions, equivalence	 classes,  and	collating  se-
	      quences within pathname expansion	and pattern matching.
       LC_CTYPE
	      This  variable  determines  the interpretation of	characters and
	      the behavior of character	classes	within pathname	expansion  and
	      pattern matching.
       LC_MESSAGES
	      This  variable  determines  the locale used to translate double-
	      quoted strings preceded by a $.
       LC_NUMERIC
	      This variable determines the locale  category  used  for	number
	      formatting.
       LINES  Used  by	the  select  builtin  command  to determine the	column
	      length for printing selection lists.  Automatically set upon re-
	      ceipt of a SIGWINCH.
       MAIL   If  this	parameter is set to a file name	and the	MAILPATH vari-
	      able is not set, bash informs the	user of	the arrival of mail in
	      the specified file.
       MAILCHECK
	      Specifies	 how often (in seconds)	bash checks for	mail.  The de-
	      fault is 60 seconds.  When it is time to	check  for  mail,  the
	      shell  does  so  before  displaying the primary prompt.  If this
	      variable is unset, or set	to  a  value  that  is	not  a	number
	      greater than or equal to zero, the shell disables	mail checking.
       MAILPATH
	      A	 colon-separated  list	of  file names to be checked for mail.
	      The message to be	printed	when mail arrives in a particular file
	      may  be  specified  by separating	the file name from the message
	      with a `?'.  When	used in	the text of the	message, $_ expands to
	      the name of the current mailfile.	 Example:
	      MAILPATH='/var/mail/bfox?"You  have  mail":~/shell-mail?"$_  has
	      mail!"'
	      Bash supplies a default value for	this variable, but  the	 loca-
	      tion  of	the  user  mail	files that it uses is system dependent
	      (e.g., /var/mail/$USER).
       OPTERR If set to	the value 1, bash displays error messages generated by
	      the  getopts builtin command (see	SHELL BUILTIN COMMANDS below).
	      OPTERR is	initialized to 1 each time the shell is	invoked	 or  a
	      shell script is executed.
       PATH   The  search  path	for commands.  It is a colon-separated list of
	      directories in which the shell looks for commands	 (see  COMMAND
	      EXECUTION	 below).   A  zero-length (null) directory name	in the
	      value of PATH indicates the current directory.  A	null directory
	      name  may	 appear	 as  two  adjacent colons, or as an initial or
	      trailing colon.  The default path	is  system-dependent,  and  is
	      set  by  the administrator who installs bash.  A common value is
	      ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''.
       POSIXLY_CORRECT
	      If this variable is in the environment  when  bash  starts,  the
	      shell  enters posix mode before reading the startup files, as if
	      the --posix invocation option had	been supplied.	If it  is  set
	      while  the  shell	is running, bash enables posix mode, as	if the
	      command set -o posix had been executed.
       PROMPT_COMMAND
	      If set, the value	is executed as a command prior to issuing each
	      primary prompt.
       PROMPT_DIRTRIM
	      If  set  to a number greater than	zero, the value	is used	as the
	      number of	trailing directory components to retain	when expanding
	      the  \w  and  \W	prompt	string	escapes	(see PROMPTING below).
	      Characters removed are replaced with an ellipsis.
       PS1    The value	of this	parameter is expanded  (see  PROMPTING	below)
	      and  used	 as  the  primary prompt string.  The default value is
	      ``\u@\h\$	''.
       PS2    The value	of this	parameter is expanded as with PS1 and used  as
	      the secondary prompt string.  The	default	is ``> ''.
       PS3    The value	of this	parameter is used as the prompt	for the	select
	      command (see SHELL GRAMMAR above).
       PS4    The value	of this	parameter is expanded  as  with	 PS1  and  the
	      value is printed before each command bash	displays during	an ex-
	      ecution trace.  The first	character of PS4 is replicated	multi-
	      ple times, as necessary, to indicate multiple levels of indirec-
	      tion.  The default is ``+	''.
       SHELL  The full pathname	to the shell is	kept in	this environment vari-
	      able.   If  it is	not set	when the shell starts, bash assigns to
	      it the full pathname of the current user's login shell.
       TIMEFORMAT
	      The value	of this	parameter is used as a format string  specify-
	      ing  how	the timing information for pipelines prefixed with the
	      time reserved word should	be displayed.  The % character	intro-
	      duces  an	 escape	 sequence  that	is expanded to a time value or
	      other information.  The escape sequences and their meanings  are
	      as follows; the braces denote optional portions.
	      %%	A literal %.
	      %[p][l]R	The elapsed time in seconds.
	      %[p][l]U	The number of CPU seconds spent	in user	mode.
	      %[p][l]S	The number of CPU seconds spent	in system mode.
	      %P	The CPU	percentage, computed as	(%U + %S) / %R.

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

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

	      If this variable is not set, bash	acts as	if it  had  the	 value
	      $'\nreal\t%3lR\nuser\t%3lU\nsys%3lS'.   If the value is null, no
	      timing information is displayed.	A trailing  newline  is	 added
	      when the format string is	displayed.

       TMOUT  If set to	a value	greater	than zero, TMOUT is treated as the de-
	      fault timeout for	the read builtin.  The select  command	termi-
	      nates if input does not arrive after TMOUT seconds when input is
	      coming from a terminal.  In an interactive shell,	the  value  is
	      interpreted as the number	of seconds to wait for input after is-
	      suing the	primary	prompt.	 Bash  terminates  after  waiting  for
	      that number of seconds if	input does not arrive.

       TMPDIR If  set, Bash uses its value as the name of a directory in which
	      Bash creates temporary files for the shell's use.

       auto_resume
	      This variable controls how the shell interacts with the user and
	      job  control.   If this variable is set, single word simple com-
	      mands without redirections are treated as	candidates for resump-
	      tion of an existing stopped job.	There is no ambiguity allowed;
	      if there is more than one	job beginning with the	string	typed,
	      the  job	most  recently	accessed  is  selected.	 The name of a
	      stopped job, in this context, is the command line	used to	 start
	      it.   If	set to the value exact,	the string supplied must match
	      the name of a stopped job	exactly;  if  set  to  substring,  the
	      string  supplied	needs  to  match  a substring of the name of a
	      stopped job.  The	substring value	provides functionality	analo-
	      gous  to the %?  job identifier (see JOB CONTROL below).	If set
	      to any other value, the supplied string must be a	 prefix	 of  a
	      stopped job's name; this provides	functionality analogous	to the
	      %string job identifier.

       histchars
	      The two or three characters which	control	history	expansion  and
	      tokenization (see	HISTORY	EXPANSION below).  The first character
	      is the history expansion character, the character	which  signals
	      the  start  of  a	 history  expansion, normally `!'.  The	second
	      character	is the quick substitution character, which is used  as
	      shorthand	 for  re-running the previous command entered, substi-
	      tuting one string	for another in the command.   The  default  is
	      `^'.   The optional third	character is the character which indi-
	      cates that the remainder of the line is a	comment	when found  as
	      the  first  character of a word, normally	`#'.  The history com-
	      ment character causes history substitution to be skipped for the
	      remaining	 words on the line.  It	does not necessarily cause the
	      shell parser to treat the	rest of	the line as a comment.

   Arrays
       Bash provides one-dimensional indexed and associative array  variables.
       Any  variable may be used as an indexed array; the declare builtin will
       explicitly declare an array.  There is no maximum limit on the size  of
       an  array, nor any requirement that members be indexed or assigned con-
       tiguously.  Indexed arrays are  referenced  using  integers  (including
       arithmetic  expressions)	  and  are  zero-based;	associative arrays are
       referenced using	arbitrary strings.

       An indexed array	is created automatically if any	variable  is  assigned
       to using	the syntax name[subscript]=value.  The subscript is treated as
       an arithmetic expression	that must evaluate to a	number greater than or
       equal  to zero.	To explicitly declare an indexed array,	use declare -a
       name (see SHELL BUILTIN COMMANDS	below).	 declare -a name[subscript] is
       also accepted; the subscript is ignored.

       Associative arrays are created using declare -A name.

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

       Arrays  are  assigned  to  using	 compound  assignments	of  the	  form
       name=(value1  ...  valuen),  where  each	 value	is  of	the form [sub-
       script]=string.	Indexed	array assignments do not require  the  bracket
       and  subscript.	 When  assigning  to  indexed  arrays, if the optional
       brackets	and subscript are supplied, that index is assigned to;	other-
       wise the	index of the element assigned is the last index	assigned to by
       the statement plus one.	Indexing starts	at zero.

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

       This syntax is also accepted by the declare builtin.  Individual	 array
       elements	 may be	assigned to using the name[subscript]=value syntax in-
       troduced	above.

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

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

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

       The  declare,  local,  and readonly builtins each accept	a -a option to
       specify an indexed array	and a -A option	to specify an associative  ar-
       ray.   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 assign-
       ments.

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

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

       On systems that can support it, there is	an additional expansion	avail-
       able: process substitution.

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

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

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

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

       Brace expansion is performed before any other expansions, and any char-
       acters special to other expansions are preserved	in the result.	It  is
       strictly	 textual.  Bash	does not apply any syntactic interpretation to
       the context of the expansion or the text	between	the braces.

       A correctly-formed brace	expansion must contain	unquoted  opening  and
       closing braces, and at least one	unquoted comma or a valid sequence ex-
       pression.  Any incorrectly formed brace expansion is left unchanged.  A
       {  or  ,	may be quoted with a backslash to prevent its being considered
       part of a brace expression.  To avoid conflicts with  parameter	expan-
       sion, the string	${ is not considered eligible for brace	expansion.

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

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

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

   Tilde Expansion
       If a word begins	with an	unquoted tilde character  (`~'),  all  of  the
       characters  preceding  the  first unquoted slash	(or all	characters, if
       there is	no unquoted slash) are considered a tilde-prefix.  If none  of
       the  characters	in  the	tilde-prefix are quoted, the characters	in the
       tilde-prefix following the tilde	are treated as a possible login	 name.
       If  this	 login name is the null	string,	the tilde is replaced with the
       value of	the shell parameter HOME.  If HOME is unset, the  home	direc-
       tory  of	 the  user executing the shell is substituted instead.	Other-
       wise, the tilde-prefix is replaced with the home	 directory  associated
       with the	specified login	name.

       If  the tilde-prefix is a `~+', the value of the	shell variable PWD re-
       places the tilde-prefix.	 If the	tilde-prefix is	a `~-',	the  value  of
       the  shell variable OLDPWD, if it is set, is substituted.  If the char-
       acters following	the tilde in the tilde-prefix consist of a  number  N,
       optionally  prefixed  by	 a  `+'	or a `-', the tilde-prefix is replaced
       with the	corresponding element from the directory stack,	as it would be
       displayed by the	dirs builtin invoked with the tilde-prefix as an argu-
       ment.  If the characters	following the tilde in the  tilde-prefix  con-
       sist of a number	without	a leading `+' or `-', `+' is assumed.

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

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

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

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

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

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

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

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

       ${parameter:-word}
	      Use  Default  Values.  If	parameter is unset or null, the	expan-
	      sion of word is substituted.  Otherwise, the value of  parameter
	      is substituted.
       ${parameter:=word}
	      Assign  Default  Values.	If parameter is	unset or null, the ex-
	      pansion of word is assigned to parameter.	 The value of  parame-
	      ter  is then substituted.	 Positional parameters and special pa-
	      rameters may not be assigned to in this way.
       ${parameter:?word}
	      Display Error if Null or Unset.  If parameter is null or	unset,
	      the  expansion  of  word (or a message to	that effect if word is
	      not present) is written to the standard error and	the shell,  if
	      it is not	interactive, exits.  Otherwise,	the value of parameter
	      is substituted.
       ${parameter:+word}
	      Use Alternate Value.  If parameter is null or unset, nothing  is
	      substituted, otherwise the expansion of word is substituted.
       ${parameter:offset}
       ${parameter:offset:length}
	      Substring	 Expansion.  Expands to	up to length characters	of pa-
	      rameter starting at  the	character  specified  by  offset.   If
	      length  is omitted, expands to the substring of parameter	start-
	      ing at the character specified by	offset.	 length	and offset are
	      arithmetic   expressions	 (see  ARITHMETIC  EVALUATION  below).
	      length must evaluate to a	number greater than or equal to	 zero.
	      If  offset  evaluates  to	 a number less than zero, the value is
	      used as an offset	from the end of	the value  of  parameter.   If
	      parameter	 is  @,	the result is length positional	parameters be-
	      ginning at offset.  If parameter is an indexed array  name  sub-
	      scripted	by @ or	*, the result is the length members of the ar-
	      ray beginning with ${parameter[offset]}.	A negative  offset  is
	      taken  relative  to  one	greater	 than the maximum index	of the
	      specified	array.	Substring expansion applied to an  associative
	      array  produces  undefined results.  Note	that a negative	offset
	      must be separated	from the colon by at least one space to	 avoid
	      being  confused  with  the  :- expansion.	 Substring indexing is
	      zero-based unless	the positional parameters are used,  in	 which
	      case  the	 indexing starts at 1 by default.  If 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.

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

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

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

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

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

	      $(command)
       or
	      `command`

       Bash performs the expansion by executing	command	and replacing the com-
       mand substitution with the standard output of  the  command,  with  any
       trailing	newlines deleted.  Embedded newlines are not deleted, but they
       may be removed during word splitting.  The command  substitution	 $(cat
       file) can be replaced by	the equivalent but faster $(< file).

       When  the  old-style  backquote form of substitution is used, backslash
       retains its literal meaning except when followed	by $, `,  or  \.   The
       first backquote not preceded by a backslash terminates the command sub-
       stitution.  When	using the $(command) form, all characters between  the
       parentheses make	up the command;	none are treated specially.

       Command substitutions may be nested.  To	nest when using	the backquoted
       form, escape the	inner backquotes with backslashes.

       If the substitution appears within double quotes,  word	splitting  and
       pathname	expansion are not performed on the results.

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

	      $((expression))

       The  expression	is  treated  as	if it were within double quotes, but a
       double quote inside the parentheses is not treated specially.  All  to-
       kens  in	 the expression	undergo	parameter expansion, string expansion,
       command substitution, and quote removal.	 Arithmetic expansions may  be
       nested.

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

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

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

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

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

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

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

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

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

       Pattern Matching

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

       The special pattern characters have the following meanings:

       *      Matches any string, including the	null string.  When  the	 glob-
	      star shell option	is enabled, and	* is used in a pathname	expan-
	      sion context, two	adjacent *s used  as  a	 single	 pattern  will
	      match all	files and zero or more directories and subdirectories.
	      If followed by a /, two adjacent *s will match only  directories
	      and subdirectories.
       ?      Matches any single character.
       [...]  Matches  any  one	of the enclosed	characters.  A pair of charac-
	      ters separated by	a hyphen denotes a range expression; any char-
	      acter  that sorts	between	those two characters, inclusive, using
	      the current locale's collating sequence and  character  set,  is
	      matched.	 If the	first character	following the [	is a !	or a ^
	      then any character not enclosed is matched.  The	sorting	 order
	      of  characters in	range expressions is determined	by the current
	      locale and the value of the LC_COLLATE shell variable,  if  set.
	      A	 - may be matched by including it as the first or last charac-
	      ter 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 char-
	      acter _.

	      Within [ and ], an equivalence class can be specified using  the
	      syntax  [=c=], which matches all characters with the same	colla-
	      tion weight (as defined by the current locale) as	the  character
	      c.

	      Within [ and ], the syntax [.symbol.] matches the	collating sym-
	      bol symbol.

       If the extglob shell option is enabled using the	shopt builtin, several
       extended	 pattern  matching operators are recognized.  In the following
       description, a pattern-list is a	list of	one or more patterns separated
       by a |.	Composite patterns may be formed using one or more of the fol-
       lowing sub-patterns:

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

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

REDIRECTION
       Before a	command	is executed, its input and output  may	be  redirected
       using  a	 special  notation  interpreted	by the shell.  Redirection may
       also be used to open and	close files for	the  current  shell  execution
       environment.  The following redirection operators may precede or	appear
       anywhere	within a simple	command	or may follow a	command.  Redirections
       are processed in	the order they appear, from left to right.

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

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

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

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 >	dirlist

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

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

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

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

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

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

       The general format for redirecting input	is:

	      [n]<word

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

       The general format for redirecting output is:

	      [n]>word

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

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

       The general format for appending	output is:

	      [n]>>word

   Redirecting Standard	Output and Standard Error
       This construct allows both the standard output (file descriptor 1)  and
       the  standard  error output (file descriptor 2) to be redirected	to the
       file whose name is the expansion	of word.

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

	      &>word
       and
	      >&word

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

	      >word 2>&1

   Appending Standard Output and Standard Error
       This construct allows both the standard output (file descriptor 1)  and
       the  standard  error  output  (file descriptor 2) to be appended	to the
       file whose name is the expansion	of word.

       The format for appending	standard output	and standard error is:

	      &>>word

       This is semantically equivalent to

	      >>word 2>&1

   Here	Documents
       This type of redirection	instructs the shell to	read  input  from  the
       current source until a line containing only delimiter (with no trailing
       blanks) is seen.	 All of	the lines read up to that point	are then  used
       as the standard input for a command.

       The format of here-documents is:

	      <<[-]word
		      here-document
	      delimiter

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

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

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

	      <<<word

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

   Duplicating File Descriptors
       The redirection operator

	      [n]<&word

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

       The operator

	      [n]>&word

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

   Moving File Descriptors
       The redirection operator

	      [n]<&digit-

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

       Similarly, the redirection operator

	      [n]>&digit-

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

   Opening File	Descriptors for	Reading	and Writing
       The redirection operator

	      [n]<>word

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

ALIASES
       Aliases allow a string to be substituted	for a word when	it is used  as
       the  first  word	 of  a	simple command.	 The shell maintains a list of
       aliases that may	be set and unset with the alias	 and  unalias  builtin
       commands	 (see  SHELL  BUILTIN COMMANDS below).	The first word of each
       simple command, if unquoted, is checked to see if it has	an alias.   If
       so,  that word is replaced by the text of the alias.  The characters /,
       $, `, and = and any of the shell	metacharacters or  quoting  characters
       listed above may	not appear in an alias name.  The replacement text may
       contain any valid shell input,  including  shell	 metacharacters.   The
       first  word  of	the replacement	text is	tested for aliases, but	a word
       that is identical to an alias being expanded is not expanded  a	second
       time.   This  means  that  one may alias	ls to ls -F, for instance, and
       bash does not try to recursively	expand the replacement text.   If  the
       last  character	of  the	 alias value is	a blank, then the next command
       word following the alias	is also	checked	for alias expansion.

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

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

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

       The  rules  concerning  the  definition and use of aliases are somewhat
       confusing.  Bash	always reads at	least one complete line	of  input  be-
       fore  executing any of the commands on that line.  Aliases are expanded
       when a command is read, not when	it is executed.	 Therefore,  an	 alias
       definition  appearing on	the same line as another command does not take
       effect until the	next line of input is read.   The  commands  following
       the  alias  definition  on that line are	not affected by	the new	alias.
       This behavior is	also an	issue when functions  are  executed.   Aliases
       are  expanded when a function definition	is read, not when the function
       is executed, because a function definition is itself  a	compound  com-
       mand.   As  a consequence, aliases defined in a function	are not	avail-
       able until after	that function is executed.  To	be  safe,  always  put
       alias  definitions on a separate	line, and do not use alias in compound
       commands.

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

FUNCTIONS
       A shell function, defined  as  described	 above	under  SHELL  GRAMMAR,
       stores  a  series  of commands for later	execution.  When the name of a
       shell function is used as a simple command name,	the list  of  commands
       associated with that function name is executed.	Functions are executed
       in the context of the current shell; no new process is created  to  in-
       terpret	them  (contrast	 this  with  the execution of a	shell script).
       When a function is executed, the	arguments to the function  become  the
       positional parameters during its	execution.  The	special	parameter # is
       updated to reflect the change.  Special parameter 0 is unchanged.   The
       first  element of the FUNCNAME variable is set to the name of the func-
       tion while the function is executing.

       All other aspects of the	shell execution	environment are	identical  be-
       tween  a	 function and its caller with these exceptions:	 the DEBUG and
       RETURN traps (see the description  of  the  trap	 builtin  under	 SHELL
       BUILTIN	COMMANDS below)	are not	inherited unless the function has been
       given the trace attribute (see the description of the  declare  builtin
       below)  or  the -o functrace shell option has been enabled with the set
       builtin (in which case all  functions  inherit  the  DEBUG  and	RETURN
       traps),	and the	ERR trap is not	inherited unless the -o	errtrace shell
       option has been enabled.

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

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

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

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

ARITHMETIC EVALUATION
       The  shell allows arithmetic expressions	to be evaluated, under certain
       circumstances (see the let and declare builtin commands and  Arithmetic
       Expansion).   Evaluation	 is done in fixed-width	integers with no check
       for overflow, though division by	0 is trapped and flagged as an	error.
       The  operators  and their precedence, associativity, and	values are the
       same as in the C	language.  The following list of operators is  grouped
       into  levels  of	 equal-precedence operators.  The levels are listed in
       order of	decreasing precedence.

       id++ id--
	      variable post-increment and post-decrement
       ++id --id
	      variable pre-increment and pre-decrement
       - +    unary minus and plus
       ! ~    logical and bitwise negation
       **     exponentiation
       * / %  multiplication, division,	remainder
       + -    addition,	subtraction
       << >>  left and right bitwise shifts
       <= >= < >
	      comparison
       == !=  equality and inequality
       &      bitwise AND
       ^      bitwise exclusive	OR
       |      bitwise OR
       &&     logical AND
       ||     logical OR
       expr?expr:expr
	      conditional operator
       = *= /= %= += -=	<<= >>=	&= ^= |=
	      assignment
       expr1 , expr2
	      comma

       Shell variables are allowed as operands;	parameter  expansion  is  per-
       formed before the expression is evaluated.  Within an expression, shell
       variables may also be referenced	by name	without	 using	the  parameter
       expansion  syntax.  A shell variable that is null or unset evaluates to
       0 when referenced by name without using the parameter expansion syntax.
       The  value  of a	variable is evaluated as an arithmetic expression when
       it is referenced, or when a variable which has been given  the  integer
       attribute using declare -i is assigned a	value.	A null value evaluates
       to 0.  A	shell variable need not	have its integer attribute  turned  on
       to be used in an	expression.

       Constants with a	leading	0 are interpreted as octal numbers.  A leading
       0x or  0X  denotes  hexadecimal.	  Otherwise,  numbers  take  the  form
       [base#]n,  where	base is	a decimal number between 2 and 64 representing
       the arithmetic base, and	n is a number in that base.  If	base# is omit-
       ted,  then  base	10 is used.  The digits	greater	than 9 are represented
       by the lowercase	letters, the uppercase letters,	@, and _, in that  or-
       der.  If	base is	less than or equal to 36, lowercase and	uppercase let-
       ters may	be used	interchangeably	to represent numbers  between  10  and
       35.

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

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

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

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

       -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.
       -O file
	      True if file exists and is owned by the effective	user id.
       -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.
       -S file
	      True if file exists and is a socket.
       -N file
	      True  if	file  exists  and  has been modified since it was last
	      read.
       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.
       file1 -ef file2
	      True if file1 and	file2 refer to the same	device and inode  num-
	      bers.
       -o optname
	      True  if	shell  option optname is enabled.  See the list	of op-
	      tions under the description of the -o option to the set  builtin
	      below.
       -z string
	      True if the length of string is zero.
       string
       -n string
	      True if the length of string is non-zero.

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

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

       string1 < string2
	      True if string1 sorts before string2 lexicographically.

       string1 > string2
	      True if string1 sorts after string2 lexicographically.

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

SIMPLE COMMAND EXPANSION
       When a simple command is	executed, the shell performs the following ex-
       pansions, assignments, and redirections,	from left to right.

       1.     The  words  that	the  parser has	marked as variable assignments
	      (those preceding the command name) and  redirections  are	 saved
	      for later	processing.

       2.     The  words that are not variable assignments or redirections are
	      expanded.	 If any	words remain after expansion, the  first  word
	      is  taken	 to be the name	of the command and the remaining words
	      are the arguments.

       3.     Redirections are performed as described above under REDIRECTION.

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

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

       If no command name results, redirections	are performed, but do not  af-
       fect  the  current  shell  environment.	A redirection error causes the
       command to exit with a non-zero status.

       If there	is a command name left after expansion,	execution proceeds  as
       described  below.   Otherwise, the command exits.  If one of the	expan-
       sions contained a command substitution, the exit	status of the  command
       is  the	exit  status  of  the last command substitution	performed.  If
       there were no command substitutions, the	command	exits with a status of
       zero.

COMMAND	EXECUTION
       After  a	 command  has been split into words, if	it results in a	simple
       command and an optional list of arguments, the  following  actions  are
       taken.

       If  the	command	name contains no slashes, the shell attempts to	locate
       it.  If there exists a shell function by	that name,  that  function  is
       invoked	as described above in FUNCTIONS.  If the name does not match a
       function, the shell searches for	it in the list of shell	builtins.   If
       a match is found, that builtin is invoked.

       If  the name is neither a shell function	nor a builtin, and contains no
       slashes,	bash searches each element of the PATH for  a  directory  con-
       taining an executable file by that name.	 Bash uses a hash table	to re-
       member the full pathnames of executable files  (see  hash  under	 SHELL
       BUILTIN	COMMANDS  below).  A full search of the	directories in PATH is
       performed only if the command is	not found in the hash table.   If  the
       search is unsuccessful, the shell searches for a	defined	shell function
       named command_not_found_handle.	If that	function exists, it is invoked
       with  the  original command and the original command's arguments	as its
       arguments, and the function's exit status becomes the  exit  status  of
       the  shell.  If that function is	not defined, the shell prints an error
       message and returns an exit status of 127.

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

       If  this	 execution fails because the file is not in executable format,
       and the file is not a directory,	it is assumed to be a shell script,  a
       file  containing	 shell commands.  A subshell is	spawned	to execute it.
       This subshell reinitializes itself, so that the effect is as if	a  new
       shell  had  been	 invoked to handle the script, with the	exception that
       the locations of	commands remembered by the parent (see hash below  un-
       der SHELL BUILTIN COMMANDS) are retained	by the child.

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

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

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

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

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

       o      current traps set	by trap

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

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

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

       o      options enabled by shopt

       o      shell aliases defined with alias

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

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

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

       o      the current working directory

       o      the file creation	mode mask

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

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

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

       Command substitution, commands grouped with parentheses,	and  asynchro-
       nous commands are invoked in a subshell environment that	is a duplicate
       of the shell environment, except	that traps caught by the shell are re-
       set  to	the values that	the shell inherited from its parent at invoca-
       tion.  Builtin commands that are	invoked	as part	of a pipeline are also
       executed	in a subshell environment.  Changes made to the	subshell envi-
       ronment cannot affect the shell's execution environment.

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

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

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

       The  shell provides several ways	to manipulate the environment.	On in-
       vocation, the shell scans its own environment and creates  a  parameter
       for  each name found, automatically marking it for export to child pro-
       cesses.	Executed commands inherit the environment.  The	export and de-
       clare  -x  commands  allow  parameters and functions to be added	to and
       deleted from the	environment.  If the value of a	parameter in the envi-
       ronment is modified, the	new value becomes part of the environment, re-
       placing the old.	 The environment inherited  by	any  executed  command
       consists	 of the	shell's	initial	environment, whose values may be modi-
       fied in the shell, less any pairs removed by the	 unset	command,  plus
       any additions via the export and	declare	-x commands.

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

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

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

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

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

       If a command is not found, the child process created to execute it  re-
       turns  a	 status	 of 127.  If a command is found	but is not executable,
       the return status is 126.

       If a command fails because of an	error during expansion or redirection,
       the exit	status is greater than zero.

       Shell  builtin  commands	return a status	of 0 (true) if successful, and
       non-zero	(false)	if an error occurs while they execute.	 All  builtins
       return an exit status of	2 to indicate incorrect	usage.

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

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

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

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

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

       If  bash	is waiting for a command to complete and receives a signal for
       which a trap has	been set, the trap will	not be executed	until the com-
       mand  completes.	  When bash is waiting for an asynchronous command via
       the wait	builtin, the reception of a signal for which a trap  has  been
       set will	cause the wait builtin to return immediately with an exit sta-
       tus greater than	128, immediately after which the trap is executed.

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

       The shell associates a job with each pipeline.  It  keeps  a  table  of
       currently  executing  jobs,  which may be listed	with the jobs command.
       When bash starts	a job asynchronously (in the background), it prints  a
       line that looks like:

	      [1] 25647

       indicating that this job	is job number 1	and that the process ID	of the
       last process in the pipeline associated with this job is	25647.	All of
       the  processes  in a single pipeline are	members	of the same job.  Bash
       uses the	job abstraction	as the basis for job control.

       To facilitate the implementation	of the user interface to job  control,
       the operating system maintains the notion of a current terminal process
       group ID.  Members of this process group	(processes whose process group
       ID is equal to the current terminal process group ID) receive keyboard-
       generated signals such as SIGINT.  These	processes are said  to	be  in
       the  foreground.	 Background processes are those	whose process group ID
       differs from the	terminal's; such processes are immune to keyboard-gen-
       erated signals.	Only foreground	processes are allowed to read from or,
       if the user so specifies	with  stty  tostop,  write  to	the  terminal.
       Background  processes  which  attempt  to read from (write to when stty
       tostop is in effect) the	terminal are sent a SIGTTIN  (SIGTTOU)	signal
       by  the	kernel's  terminal  driver, which, unless caught, suspends the
       process.

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

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

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

       The shell learns	immediately whenever a job changes  state.   Normally,
       bash waits until	it is about to print a prompt before reporting changes
       in a job's status so as to not interrupt	any other output.  If  the  -b
       option to the set builtin command is enabled, bash reports such changes
       immediately.  Any trap on SIGCHLD is executed for each child  that  ex-
       its.

       If  an  attempt to exit bash is made while jobs are stopped (or,	if the
       checkjobs shell option has been enabled using the shopt	builtin,  run-
       ning), the shell	prints a warning message, and, if the checkjobs	option
       is enabled, lists the jobs and their statuses.  The  jobs  command  may
       then  be	 used to inspect their status.	If a second attempt to exit is
       made without an intervening command, the	shell does not	print  another
       warning,	and any	stopped	jobs are terminated.

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

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

READLINE
       This  is	 the library that handles reading input	when using an interac-
       tive shell, unless the --noediting option is given at shell invocation.
       Line editing is also used when using the	-e option to the read builtin.
       By default, the line editing commands are similar to those of emacs.  A
       vi-style	line editing interface is also available.  Line	editing	can be
       enabled at any time using the -o	emacs or -o  vi	 options  to  the  set
       builtin	(see  SHELL BUILTIN COMMANDS below).  To turn off line editing
       after the shell is running, use the +o emacs or +o vi  options  to  the
       set builtin.

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

       Readline	commands may be	given numeric arguments, which normally	act as
       a repeat	count.	Sometimes, however, it is the  sign  of	 the  argument
       that  is	 significant.	Passing	 a negative argument to	a command that
       acts in the forward direction (e.g., kill-line) causes that command  to
       act  in	a  backward direction.	Commands whose behavior	with arguments
       deviates	from this are noted below.

       When a command is described as killing text, the	text deleted is	 saved
       for possible future retrieval (yanking).	 The killed text is saved in a
       kill ring.  Consecutive kills cause the text to be accumulated into one
       unit, which can be yanked all at	once.  Commands	which do not kill text
       separate	the chunks of text on the kill ring.

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

       The default key-bindings	may be changed with an	inputrc	 file.	 Other
       programs	that use this library may add their own	commands and bindings.

       For example, placing

	      M-Control-u: universal-argument
       or
	      C-Meta-u:	universal-argument
       into  the inputrc would make M-C-u execute the readline command univer-
       sal-argument.

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

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

   Readline Key	Bindings
       The syntax for controlling key bindings in the inputrc file is  simple.
       All  that is required is	the name of the	command	or the text of a macro
       and a key sequence to which it should be	bound. The name	may be	speci-
       fied in one of two ways:	as a symbolic key name,	possibly with Meta- or
       Control-	prefixes, or as	a key sequence.

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

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

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

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

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

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

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

       In addition to the GNU Emacs style escape sequences, a  second  set  of
       backslash escapes is available:
	      \a     alert (bell)
	      \b     backspace
	      \d     delete
	      \f     form feed
	      \n     newline
	      \r     carriage return
	      \t     horizontal	tab
	      \v     vertical tab
	      \nnn   the  eight-bit  character	whose value is the octal value
		     nnn (one to three digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (one or two hex digits)

       When entering the text of a macro, single or double quotes must be used
       to indicate a macro definition.	Unquoted text is assumed to be a func-
       tion  name.   In	 the macro body, the backslash escapes described above
       are expanded.  Backslash	will quote any other character	in  the	 macro
       text, including " and '.

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

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

	      set variable-name	value

       Except where noted, readline variables can take the values  On  or  Off
       (without	 regard	 to  case).   Unrecognized variable names are ignored.
       When a variable value is	read, empty or null values, "on"  (case-insen-
       sitive),	and "1"	are equivalent to On.  All other values	are equivalent
       to Off.	The variables and their	default	values are:

       bell-style (audible)
	      Controls what happens when readline wants	to ring	 the  terminal
	      bell.  If	set to none, readline never rings the bell.  If	set to
	      visible, readline	uses a visible bell if one is  available.   If
	      set to audible, readline attempts	to ring	the terminal's bell.
       bind-tty-special-chars (On)
	      If  set  to On, readline attempts	to bind	the control characters
	      treated specially	by the kernel's	terminal driver	to their read-
	      line equivalents.
       comment-begin (``#'')
	      The  string  that	 is  inserted when the readline	insert-comment
	      command is executed.  This command is bound to M-# in emacs mode
	      and to # in vi command mode.
       completion-ignore-case (Off)
	      If set to	On, readline performs filename matching	and completion
	      in a case-insensitive fashion.
       completion-prefix-display-length	(0)
	      The length in characters of the common prefix of a list of  pos-
	      sible  completions that is displayed without modification.  When
	      set to a value greater than zero,	common	prefixes  longer  than
	      this  value are replaced with an ellipsis	when displaying	possi-
	      ble completions.
       completion-query-items (100)
	      This determines when the user is queried about viewing the  num-
	      ber  of  possible	 completions generated by the possible-comple-
	      tions command.  It may be	set to any integer value greater  than
	      or  equal	 to  zero.   If	 the number of possible	completions is
	      greater than or equal to the value of this variable, the user is
	      asked  whether or	not he wishes to view them; otherwise they are
	      simply listed on the terminal.
       convert-meta (On)
	      If set to	On, readline will convert characters with  the	eighth
	      bit set to an ASCII key sequence by stripping the	eighth bit and
	      prefixing	an escape character (in	effect,	using  escape  as  the
	      meta prefix).
       disable-completion (Off)
	      If set to	On, readline will inhibit word completion.  Completion
	      characters will be inserted into the line	as if  they  had  been
	      mapped to	self-insert.
       editing-mode (emacs)
	      Controls whether readline	begins with a set of key bindings sim-
	      ilar to emacs or vi.  editing-mode can be	set to either emacs or
	      vi.
       echo-control-characters (On)
	      When  set	to On, on operating systems that indicate they support
	      it, readline echoes a character corresponding to a signal	gener-
	      ated from	the keyboard.
       enable-keypad (Off)
	      When set to On, readline will try	to enable the application key-
	      pad when it is called.  Some systems need	this to	enable the ar-
	      row keys.
       enable-meta-key (On)
	      When  set	 to  On, readline will try to enable any meta modifier
	      key the terminal claims to support when it is called.   On  many
	      terminals, the meta key is used to send eight-bit	characters.
       expand-tilde (Off)
	      If  set  to  on,	tilde expansion	is performed when readline at-
	      tempts word completion.
       history-preserve-point (Off)
	      If set to	on, the	history	code attempts to place	point  at  the
	      same  location on	each history line retrieved with previous-his-
	      tory or next-history.
       history-size (0)
	      Set the maximum number of	history	entries	saved in  the  history
	      list.  If	set to zero, the number	of entries in the history list
	      is not limited.
       horizontal-scroll-mode (Off)
	      When set to On, makes readline use a single  line	 for  display,
	      scrolling	the input horizontally on a single screen line when it
	      becomes longer than the screen width rather than wrapping	 to  a
	      new line.
       input-meta (Off)
	      If  set to On, readline will enable eight-bit input (that	is, it
	      will not strip the high bit from the characters it  reads),  re-
	      gardless	of  what the terminal claims it	can support.  The name
	      meta-flag	is a synonym for this variable.
       isearch-terminators (``C-[C-J'')
	      The string of characters that should  terminate  an  incremental
	      search  without  subsequently  executing the character as	a com-
	      mand.  If	this variable has not been given a value, the  charac-
	      ters ESC and C-J will terminate an incremental search.
       keymap (emacs)
	      Set  the current readline	keymap.	 The set of valid keymap names
	      is emacs,	emacs-standard,	emacs-meta,  emacs-ctlx,  vi,  vi-com-
	      mand,  and  vi-insert.  vi is equivalent to vi-command; emacs is
	      equivalent to emacs-standard.  The default value is  emacs;  the
	      value of editing-mode also affects the default keymap.
       mark-directories	(On)
	      If set to	On, completed directory	names have a slash appended.
       mark-modified-lines (Off)
	      If  set  to  On,	history	lines that have	been modified are dis-
	      played with a preceding asterisk (*).
       mark-symlinked-directories (Off)
	      If set to	On, completed names which are symbolic links to	direc-
	      tories  have  a slash appended (subject to the value of mark-di-
	      rectories).
       match-hidden-files (On)
	      This variable, when set to On, causes readline  to  match	 files
	      whose  names  begin  with	 a  `.'	(hidden	files) when performing
	      filename completion, unless the leading `.' is supplied  by  the
	      user in the filename to be completed.
       output-meta (Off)
	      If  set  to On, readline will display characters with the	eighth
	      bit set directly rather than as a	meta-prefixed escape sequence.
       page-completions	(On)
	      If set to	On, readline uses an internal more-like	pager to  dis-
	      play a screenful of possible completions at a time.
       print-completions-horizontally (Off)
	      If  set  to  On,	readline will display completions with matches
	      sorted horizontally in alphabetical order, rather	than down  the
	      screen.
       revert-all-at-newline (Off)
	      If  set  to  on, readline	will undo all changes to history lines
	      before returning when accept-line	is executed.  By default, his-
	      tory  lines  may	be  modified  and retain individual undo lists
	      across calls to readline.
       show-all-if-ambiguous (Off)
	      This alters the default behavior of  the	completion  functions.
	      If set to	on, words which	have more than one possible completion
	      cause the	matches	to be listed immediately  instead  of  ringing
	      the bell.
       show-all-if-unmodified (Off)
	      This  alters the default behavior	of the completion functions in
	      a	fashion	similar	to show-all-if-ambiguous.  If set to on, words
	      which  have more than one	possible completion without any	possi-
	      ble partial completion (the possible completions don't  share  a
	      common  prefix)  cause  the matches to be	listed immediately in-
	      stead of ringing the bell.
       skip-completed-text (Off)
	      If set to	On, this alters	the default completion	behavior  when
	      inserting	 a  single match into the line.	 It's only active when
	      performing completion in the middle  of  a  word.	  If  enabled,
	      readline	does  not  insert  characters from the completion that
	      match characters after point in the  word	 being	completed,  so
	      portions of the word following the cursor	are not	duplicated.
       visible-stats (Off)
	      If  set to On, a character denoting a file's type	as reported by
	      stat(2) is appended to the filename when listing	possible  com-
	      pletions.

   Readline Conditional	Constructs
       Readline	 implements  a	facility  similar in spirit to the conditional
       compilation features of the C preprocessor which	 allows	 key  bindings
       and  variable  settings	to be performed	as the result of tests.	 There
       are four	parser directives used.

       $if    The $if construct	allows bindings	to be made based on the	 edit-
	      ing  mode,  the  terminal	 being	used, or the application using
	      readline.	 The text of the test extends to the end of the	 line;
	      no characters are	required to isolate it.

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

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

	      application
		     The application construct is used to include application-
		     specific  settings.   Each	program	using the readline li-
		     brary sets	the application	name,  and  an	initialization
		     file can test for a particular value.  This could be used
		     to	bind key sequences to functions	useful for a  specific
		     program.	For instance, the following command adds a key
		     sequence that quotes the  current	or  previous  word  in
		     Bash:

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

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

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

       $include
	      This  directive takes a single filename as an argument and reads
	      commands and bindings from that file.  For example, the  follow-
	      ing directive would read /etc/inputrc:

	      $include	/etc/inputrc

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

       Incremental  searches  begin  before  the  user has finished typing the
       search string.  As each character of the	search string is typed,	 read-
       line displays the next entry from the history matching the string typed
       so far.	An incremental search requires	only  as  many	characters  as
       needed  to  find	 the desired history entry.  The characters present in
       the value of the	isearch-terminators variable are used to terminate  an
       incremental search.  If that variable has not been assigned a value the
       Escape and Control-J characters will terminate an  incremental  search.
       Control-G  will	abort  an  incremental search and restore the original
       line.  When the search is terminated, the history entry containing  the
       search string becomes the current line.

       To  find	 other matching	entries	in the history list, type Control-S or
       Control-R as appropriate.  This will search backward or forward in  the
       history	for  the  next	entry matching the search string typed so far.
       Any other key sequence bound to a readline command will	terminate  the
       search  and  execute that command.  For instance, a newline will	termi-
       nate the	search and accept the line, thereby executing the command from
       the history list.

       Readline	remembers the last incremental search string.  If two Control-
       Rs are typed without any	intervening characters defining	a  new	search
       string, any remembered search string is used.

       Non-incremental	searches read the entire search	string before starting
       to search for matching history lines.  The search string	may  be	 typed
       by the user or be part of the contents of the current line.

   Readline Command Names
       The  following  is  a list of the names of the commands and the default
       key sequences to	which they are bound.  Command names without an	accom-
       panying key sequence are	unbound	by default.  In	the following descrip-
       tions, point refers to the current cursor position, and mark refers  to
       a  cursor position saved	by the set-mark	command.  The text between the
       point and mark is referred to as	the region.

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

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

   Commands for	Changing Text
       delete-char (C-d)
	      Delete  the character at point.  If point	is at the beginning of
	      the line,	there are no characters	in  the	 line,	and  the  last
	      character	typed was not bound to delete-char, then return	EOF.
       backward-delete-char (Rubout)
	      Delete  the  character  behind the cursor.  When given a numeric
	      argument,	save the deleted text on the kill ring.
       forward-backward-delete-char
	      Delete the character under the cursor, unless the	cursor	is  at
	      the end of the line, in which case the character behind the cur-
	      sor is deleted.
       quoted-insert (C-q, C-v)
	      Add the next character typed to the line verbatim.  This is  how
	      to insert	characters like	C-q, for example.
       tab-insert (C-v TAB)
	      Insert a tab character.
       self-insert (a, b, A, 1,	!, ...)
	      Insert the character typed.
       transpose-chars (C-t)
	      Drag  the	 character  before point forward over the character at
	      point, moving point forward as well.  If point is	at the end  of
	      the  line, then this transposes the two characters before	point.
	      Negative arguments have no effect.
       transpose-words (M-t)
	      Drag the word before point past the  word	 after	point,	moving
	      point  over  that	 word  as well.	 If point is at	the end	of the
	      line, this transposes the	last two words on the line.
       upcase-word (M-u)
	      Uppercase	the current (or	following) word.  With a negative  ar-
	      gument, uppercase	the previous word, but do not move point.
       downcase-word (M-l)
	      Lowercase	 the current (or following) word.  With	a negative ar-
	      gument, lowercase	the previous word, but do not move point.
       capitalize-word (M-c)
	      Capitalize the current (or following) word.  With	a negative ar-
	      gument, capitalize the previous word, but	do not move point.
       overwrite-mode
	      Toggle  overwrite	mode.  With an explicit	positive numeric argu-
	      ment, switches to	overwrite mode.	 With an explicit non-positive
	      numeric argument,	switches to insert mode.  This command affects
	      only emacs mode; vi mode does overwrite differently.  Each  call
	      to readline() starts in insert mode.  In overwrite mode, charac-
	      ters bound to self-insert	replace	the text at point rather  than
	      pushing  the  text  to  the  right.   Characters	bound to back-
	      ward-delete-char replace	the  character	before	point  with  a
	      space.  By default, this command is unbound.

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

   Numeric Arguments
       digit-argument (M-0, M-1, ..., M--)
	      Add  this	digit to the argument already accumulating, or start a
	      new argument.  M-- starts	a negative argument.
       universal-argument
	      This is another way to specify an	argument.  If this command  is
	      followed	by one or more digits, optionally with a leading minus
	      sign, those digits define	the argument.  If the command is  fol-
	      lowed by digits, executing universal-argument again ends the nu-
	      meric argument, but is otherwise ignored.	 As a special case, if
	      this command is immediately followed by a	character that is nei-
	      ther a digit or minus sign, the argument count for the next com-
	      mand  is	multiplied  by	four.  The argument count is initially
	      one, so executing	this function the first	time makes  the	 argu-
	      ment count four, a second	time makes the argument	count sixteen,
	      and so on.

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

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

   Miscellaneous
       re-read-init-file (C-x C-r)
	      Read  in	the  contents of the inputrc file, and incorporate any
	      bindings or variable assignments found there.
       abort (C-g)
	      Abort the	current	editing	command	and ring the  terminal's  bell
	      (subject to the setting of bell-style).
       do-uppercase-version (M-a, M-b, M-x, ...)
	      If  the  metafied	character x is lowercase, run the command that
	      is bound to the corresponding uppercase character.
       prefix-meta (ESC)
	      Metafy the next character	typed.	ESC f is equivalent to Meta-f.
       undo (C-_, C-x C-u)
	      Incremental undo,	separately remembered for each line.
       revert-line (M-r)
	      Undo all changes made to this line.  This	is like	executing  the
	      undo  command  enough  times  to	return the line	to its initial
	      state.
       tilde-expand (M-&)
	      Perform tilde expansion on the current word.
       set-mark	(C-@, M-<space>)
	      Set the mark to the point.  If a numeric argument	 is  supplied,
	      the mark is set to that position.
       exchange-point-and-mark (C-x C-x)
	      Swap  the	 point	with the mark.	The current cursor position is
	      set to the saved position, and the old cursor position is	 saved
	      as the mark.
       character-search	(C-])
	      A	character is read and point is moved to	the next occurrence of
	      that character.  A negative count	searches for  previous	occur-
	      rences.
       character-search-backward (M-C-])
	      A	 character  is	read and point is moved	to the previous	occur-
	      rence of that character.	A negative count searches  for	subse-
	      quent occurrences.
       skip-csi-sequence ()
	      Read  enough  characters to consume a multi-key sequence such as
	      those defined for	keys like Home and End.	 Such sequences	 begin
	      with a Control Sequence Indicator	(CSI), usually ESC-[.  If this
	      sequence is bound	to "\[", keys producing	 such  sequences  will
	      have  no	effect	unless explicitly bound	to a readline command,
	      instead of inserting stray characters into the  editing  buffer.
	      This is unbound by default, but usually bound to ESC-[.
       insert-comment (M-#)
	      Without  a  numeric  argument,  the  value  of the readline com-
	      ment-begin variable is inserted at the beginning of the  current
	      line.  If	a numeric argument is supplied,	this command acts as a
	      toggle:  if the characters at the	beginning of the line  do  not
	      match  the value of comment-begin, the value is inserted,	other-
	      wise the characters in comment-begin are deleted from the	begin-
	      ning  of the line.  In either case, the line is accepted as if a
	      newline had been typed.	The  default  value  of	 comment-begin
	      causes  this  command  to	make the current line a	shell comment.
	      If a numeric argument causes the comment	character  to  be  re-
	      moved, the line will be executed by the shell.
       glob-complete-word (M-g)
	      The  word	 before	point is treated as a pattern for pathname ex-
	      pansion, with an asterisk	implicitly appended.  This pattern  is
	      used to generate a list of matching file names for possible com-
	      pletions.
       glob-expand-word	(C-x *)
	      The word before point is treated as a pattern for	 pathname  ex-
	      pansion,	and  the  list of matching file	names is inserted, re-
	      placing the word.	 If a numeric argument is supplied, an	aster-
	      isk is appended before pathname expansion.
       glob-list-expansions (C-x g)
	      The  list	 of  expansions	 that  would  have  been  generated by
	      glob-expand-word is displayed, and the line is  redrawn.	 If  a
	      numeric  argument	 is  supplied,	an asterisk is appended	before
	      pathname expansion.
       dump-functions
	      Print all	of the functions and their key bindings	to  the	 read-
	      line output stream.  If a	numeric	argument is supplied, the out-
	      put is formatted in such a way that it can be made  part	of  an
	      inputrc file.
       dump-variables
	      Print all	of the settable	readline variables and their values to
	      the readline output stream.  If a	numeric	argument is  supplied,
	      the  output  is formatted	in such	a way that it can be made part
	      of an inputrc file.
       dump-macros
	      Print all	of the readline	key sequences bound to macros and  the
	      strings  they  output.   If  a numeric argument is supplied, the
	      output is	formatted in such a way	that it	can be made part of an
	      inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about	the current instance of	bash.

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

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

       Once  a	compspec  has  been  found, it is used to generate the list of
       matching	words.	If a compspec is not found, the	default	 bash  comple-
       tion as described above under Completing	is performed.

       First,  the  actions  specified by the compspec are used.  Only matches
       which are prefixed by the word being completed are returned.  When  the
       -f  or -d option	is used	for filename or	directory name completion, the
       shell variable FIGNORE is used to filter	the matches.

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

       Next,  the string specified as the argument to the -W option is consid-
       ered.  The string is first split	using the characters in	the  IFS  spe-
       cial  variable  as delimiters.  Shell quoting is	honored.  Each word is
       then expanded using brace expansion,  tilde  expansion,	parameter  and
       variable	 expansion, command substitution, and arithmetic expansion, as
       described above under EXPANSION.	 The results are split using the rules
       described above under Word Splitting.  The results of the expansion are
       prefix-matched against the word being completed,	and the	matching words
       become the possible completions.

       After  these matches have been generated, any shell function or command
       specified with the -F and -C options is invoked.	 When the  command  or
       function	is invoked, the	COMP_LINE, COMP_POINT, COMP_KEY, and COMP_TYPE
       variables are assigned values as	described above	under Shell Variables.
       If  a  shell  function  is being	invoked, the COMP_WORDS	and COMP_CWORD
       variables are also set.	When the function or command is	 invoked,  the
       first  argument	is  the	 name of the command whose arguments are being
       completed, the second argument is the word  being  completed,  and  the
       third  argument	is  the	word preceding the word	being completed	on the
       current command	line.	No  filtering  of  the	generated  completions
       against	the word being completed is performed; the function or command
       has complete freedom in generating the matches.

       Any function specified with -F is invoked first.	 The function may  use
       any  of	the  shell facilities, including the compgen builtin described
       below, to generate the matches.	It must	put the	 possible  completions
       in the COMPREPLY	array variable.

       Next,  any  command specified with the -C option	is invoked in an envi-
       ronment equivalent to command substitution.  It should print a list  of
       completions,  one  per  line, to	the standard output.  Backslash	may be
       used to escape a	newline, if necessary.

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

       Finally,	any prefix and suffix specified	with the -P and	-S options are
       added to	each member of the completion list, and	the result is returned
       to the readline completion code as the list of possible completions.

       If  the previously-applied actions do not generate any matches, and the
       -o dirnames option was supplied to complete when	the compspec  was  de-
       fined, directory	name completion	is attempted.

       If  the	-o  plusdirs option was	supplied to complete when the compspec
       was defined, directory name completion is attempted and any matches are
       added to	the results of the other actions.

       By  default,  if	a compspec is found, whatever it generates is returned
       to the completion code as the full set of  possible  completions.   The
       default bash completions	are not	attempted, and the readline default of
       filename	completion is disabled.	 If the	-o bashdefault option was sup-
       plied  to complete when the compspec was	defined, the bash default com-
       pletions	are attempted if the compspec generates	no matches.  If	the -o
       default	option was supplied to complete	when the compspec was defined,
       readline's default completion will be performed if the  compspec	 (and,
       if attempted, the default bash completions) generate no matches.

       When  a	compspec  indicates that directory name	completion is desired,
       the programmable	completion functions force readline to append a	 slash
       to  completed names which are symbolic links to directories, subject to
       the value of the	mark-directories readline variable, regardless of  the
       setting of the mark-symlinked-directories readline variable.

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

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

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

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

       On startup, the history is initialized from the file named by the vari-
       able  HISTFILE  (default	~/.bash_history).  The file named by the value
       of HISTFILE is truncated, if necessary, to contain  no  more  than  the
       number  of lines	specified by the value of HISTFILESIZE.	 When the his-
       tory file is read, lines	beginning with the history  comment  character
       followed	 immediately  by a digit are interpreted as timestamps for the
       preceding history line.	These timestamps are optionally	displayed  de-
       pending	on the value of	the HISTTIMEFORMAT variable.  When an interac-
       tive shell exits, the last $HISTSIZE lines are copied from the  history
       list  to	$HISTFILE.  If the histappend shell option is enabled (see the
       description of shopt under SHELL	BUILTIN	COMMANDS below), the lines are
       appended	 to  the history file, otherwise the history file is overwrit-
       ten.  If	HISTFILE is unset, or if the history file is  unwritable,  the
       history	is  not	 saved.	  If  the HISTTIMEFORMAT variable is set, time
       stamps are written to the history file, marked with the history comment
       character,  so  they may	be preserved across shell sessions.  This uses
       the history comment character to	distinguish timestamps from other his-
       tory lines.  After saving the history, the history file is truncated to
       contain no more than HISTFILESIZE lines.	 If HISTFILESIZE is  not  set,
       no truncation is	performed.

       The  builtin  command fc	(see SHELL BUILTIN COMMANDS below) may be used
       to list or edit and re-execute a	portion	of the history list.  The his-
       tory  builtin may be used to display or modify the history list and ma-
       nipulate	the history file.  When	 using	command-line  editing,	search
       commands	 are available in each editing mode that provide access	to the
       history list.

       The shell allows	control	over which commands are	saved on  the  history
       list.  The HISTCONTROL and HISTIGNORE variables may be set to cause the
       shell to	save only a subset of the commands entered.  The cmdhist shell
       option,	if enabled, causes the shell to	attempt	to save	each line of a
       multi-line command in the same history entry, adding  semicolons	 where
       necessary  to preserve syntactic	correctness.  The lithist shell	option
       causes the shell	to save	the command with embedded newlines instead  of
       semicolons.  See	the description	of the shopt builtin below under SHELL
       BUILTIN COMMANDS	for information	on setting  and	 unsetting  shell  op-
       tions.

HISTORY	EXPANSION
       The  shell  supports a history expansion	feature	that is	similar	to the
       history expansion in csh.  This section describes what syntax  features
       are  available.	 This  feature	is  enabled by default for interactive
       shells, and can be disabled using the +H	option to the set builtin com-
       mand (see SHELL BUILTIN COMMANDS	below).	 Non-interactive shells	do not
       perform history expansion by default.

       History expansions introduce words from the history list	into the input
       stream,	making	it  easy to repeat commands, insert the	arguments to a
       previous	command	into the current input line, or	fix errors in previous
       commands	quickly.

       History	expansion  is  performed  immediately after a complete line is
       read, before the	shell breaks it	into words.  It	 takes	place  in  two
       parts.	The  first is to determine which line from the history list to
       use during substitution.	 The second is to select portions of that line
       for inclusion into the current one.  The	line selected from the history
       is the event, and the portions of that line that	 are  acted  upon  are
       words.	Various	 modifiers  are	 available  to manipulate the selected
       words.  The line	is broken into words in	the same fashion as when read-
       ing  input, so that several metacharacter-separated words surrounded by
       quotes are considered one word.	History	expansions are	introduced  by
       the  appearance	of  the	history	expansion character, which is !	by de-
       fault.  Only backslash (\) and single quotes can	quote the history  ex-
       pansion character.

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

       Several shell options settable with the shopt builtin may  be  used  to
       tailor  the behavior of history expansion.  If the histverify shell op-
       tion is enabled (see the	description of the shopt builtin  below),  and
       readline	 is  being  used,  history  substitutions  are not immediately
       passed to the shell parser.  Instead, the  expanded  line  is  reloaded
       into the	readline editing buffer	for further modification.  If readline
       is being	used, and the histreedit shell option  is  enabled,  a	failed
       history	substitution will be reloaded into the readline	editing	buffer
       for correction.	The -p option to the history builtin  command  may  be
       used  to	 see what a history expansion will do before using it.	The -s
       option to the history builtin may be used to add	commands to the	end of
       the  history  list  without  actually  executing	them, so that they are
       available for subsequent	recall.

       The shell allows	control	of the various characters used by the  history
       expansion mechanism (see	the description	of histchars above under Shell
       Variables).  The	shell uses the history comment character to mark  his-
       tory timestamps when writing the	history	file.

   Event Designators
       An  event designator is a reference to a	command	line entry in the his-
       tory list.

       !      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 line	minus n.
       !!     Refer to the previous command.  This is a	synonym	for `!-1'.
       !string
	      Refer to the most	recent command starting	with string.
       !?string[?]
	      Refer to the most	recent command containing string.  The	trail-
	      ing ? may	be omitted if string is	followed immediately by	a new-
	      line.
       ^string1^string2^
	      Quick substitution.  Repeat the last command, replacing  string1
	      with string2.  Equivalent	to ``!!:s/string1/string2/'' (see Mod-
	      ifiers below).
       !#     The entire command line typed so far.

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

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

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

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

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

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

	.  filename [arguments]
       source filename [arguments]
	      Read and execute commands	from filename in the current shell en-
	      vironment	and return the exit status of the  last	 command  exe-
	      cuted from filename.  If filename	does not contain a slash, file
	      names in PATH are	used to	find the  directory  containing	 file-
	      name.   The  file	 searched  for in PATH need not	be executable.
	      When bash	is  not	 in  posix  mode,  the	current	 directory  is
	      searched	if no file is found in PATH.  If the sourcepath	option
	      to the shopt builtin command is turned  off,  the	 PATH  is  not
	      searched.	  If any arguments are supplied, they become the posi-
	      tional parameters	when filename is executed.  Otherwise the  po-
	      sitional	parameters  are	 unchanged.   The return status	is the
	      status of	the last command exited	within the  script  (0	if  no
	      commands	are  executed),	 and false if filename is not found or
	      cannot be	read.

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

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

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

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

       break [n]
	      Exit  from  within a for,	while, until, or select	loop.  If n is
	      specified, break n levels.  n must be >= 1.   If	n  is  greater
	      than  the	number of enclosing loops, all enclosing loops are ex-
	      ited.  The return	value is 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] [dir]
	      Change the current directory to dir.  The	variable HOME  is  the
	      default  dir.   The  variable CDPATH defines the search path for
	      the directory containing dir.  Alternative  directory  names  in
	      CDPATH  are  separated by	a colon	(:).  A	null directory name in
	      CDPATH is	the same as the	current	directory,  i.e.,  ``.''.   If
	      dir begins with a	slash (/), then	CDPATH is not used. The	-P op-
	      tion says	to use the physical  directory	structure  instead  of
	      following	 symbolic  links  (see	also  the -P option to the set
	      builtin command);	the -L option forces symbolic links to be fol-
	      lowed.   An  argument  of	- is equivalent	to $OLDPWD.  If	a non-
	      empty directory 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 success-
	      fully changed; false otherwise.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       echo [-neE] [arg	...]
	      Output the args, separated by spaces,  followed  by  a  newline.
	      The return status	is always 0.  If -n is specified, the trailing
	      newline is suppressed.  If the -e	option is  given,  interpreta-
	      tion  of	the following backslash-escaped	characters is enabled.
	      The -E option disables the interpretation	of these escape	 char-
	      acters,  even  on	systems	where they are interpreted by default.
	      The xpg_echo shell option	may be used to	dynamically  determine
	      whether  or not echo expands these escape	characters by default.
	      echo does	not interpret -- to mean the end of options.  echo in-
	      terprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress further output
	      \e     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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       help [-dms] [pattern]
	      Display helpful information about	builtin	commands.  If  pattern
	      is  specified, help gives	detailed help on all commands matching
	      pattern; otherwise help for all the builtins and	shell  control
	      structures is printed.
	      -d     Display a short description of each pattern
	      -m     Display the description of	each pattern in	a manpage-like
		     format
	      -s     Display only a short usage	synopsis for each pattern
       The return status is 0 unless no	command	matches	pattern.

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

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

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

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

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

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

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

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

       logout Exit a login shell.

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

	      If -C is specified without -c,  the  default  quantum  is	 5000.
	      When callback is evaluated, it is	supplied the index of the next
	      array element to be assigned as an additional  argument.	 call-
	      back  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 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 for-
	      mat specifications, each of which	causes printing	 of  the  next
	      successive argument.  In addition	to the standard	printf(1) for-
	      mats, %b causes printf to	expand backslash escape	 sequences  in
	      the  corresponding  argument  (except that \c terminates output,
	      backslashes in \', \", and \? are	not removed, and octal escapes
	      beginning	 with \0 may contain up	to four	digits), and %q	causes
	      printf to	output the corresponding argument in a format that can
	      be reused	as shell input.

	      The  -v  option causes the output	to be assigned to the variable
	      var rather than being printed to the standard output.

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

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

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

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

       read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p
       prompt] [-t timeout] [-u	fd] [name ...]
	      One  line	 is read from the standard input, or from the file de-
	      scriptor fd supplied as an argument to the -u  option,  and  the
	      first word is assigned to	the first name,	the second word	to the
	      second name, and so on, with leftover words and their  interven-
	      ing  separators  assigned	 to the	last name.  If there are fewer
	      words read from the input	stream than names, the remaining names
	      are  assigned  empty  values.  The characters in IFS are used to
	      split the	line into words.  The backslash	character (\)  may  be
	      used  to	remove any special meaning for the next	character read
	      and for line continuation.  Options, if supplied,	have the  fol-
	      lowing meanings:
	      -a aname
		     The words are assigned to sequential indices of the array
		     variable aname, starting at 0.  aname is unset before any
		     new  values  are  assigned.  Other	name arguments are ig-
		     nored.
	      -d delim
		     The first character of delim is used to terminate the in-
		     put line, rather than newline.
	      -e     If	the standard input is coming from a terminal, readline
		     (see READLINE above) is used to obtain the	 line.	 Read-
		     line  uses	 the  current (or default, if line editing was
		     not previously active) editing settings.
	      -i text
		     If	readline is being used	to  read  the  line,  text  is
		     placed into the editing buffer before editing begins.
	      -n nchars
		     read  returns after reading nchars	characters rather than
		     waiting for a complete line of input, but honor a	delim-
		     iter  if fewer than nchars	characters are read before the
		     delimiter.
	      -N nchars
		     read returns  after  reading  exactly  nchars  characters
		     rather  than waiting for a	complete line of input,	unless
		     EOF is encountered	or read	times out.  Delimiter  charac-
		     ters  encountered	in the input are not treated specially
		     and do not	cause read to return until  nchars  characters
		     are read.
	      -p prompt
		     Display prompt on standard	error, without a trailing new-
		     line, before attempting to	read any input.	 The prompt is
		     displayed only if input is	coming from a terminal.
	      -r     Backslash does not	act as an escape character.  The back-
		     slash is considered to be part of the line.  In  particu-
		     lar,  a  backslash-newline	pair may not be	used as	a line
		     continuation.
	      -s     Silent mode.  If input is coming from a terminal, charac-
		     ters are not echoed.
	      -t timeout
		     Cause  read  to time out and return failure if a complete
		     line of input is not read within timeout seconds.	 time-
		     out  may  be  a  decimal number with a fractional portion
		     following the decimal point.  This	option is only	effec-
		     tive  if  read is reading input from a terminal, pipe, or
		     other special file; it has	no effect  when	 reading  from
		     regular  files.  If timeout is 0, read returns success if
		     input is available	 on  the  specified  file  descriptor,
		     failure  otherwise.   The exit status is greater than 128
		     if	the timeout is exceeded.
	      -u fd  Read input	from file descriptor fd.

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

       readonly	[-aApf]	[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  no  name arguments are given,	or if the -p option is
	      supplied,	a list of all readonly names is	printed.  The  -p  op-
	      tion  causes  output  to	be  displayed  in a format that	may be
	      reused as	input.	If a variable name is followed by  =word,  the
	      value  of	 the  variable is set to word.	The return status is 0
	      unless an	invalid	option is encountered, one of the names	is not
	      a	 valid shell variable name, or -f is supplied with a name that
	      is not a function.

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

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

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

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

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

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

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

	      The list of shopt	options	is:

	      autocd  If set, a	command	name that is the name of  a  directory
		      is  executed  as	if it were the argument	to the cd com-
		      mand.  This option is only used by interactive shells.
	      cdable_vars
		      If set, an argument to the cd builtin  command  that  is
		      not  a directory is assumed to be	the name of a variable
		      whose value is the directory to change to.
	      cdspell If set, minor errors in the spelling of a	directory com-
		      ponent  in  a  cd	command	will be	corrected.  The	errors
		      checked for are transposed characters, a missing charac-
		      ter,  and	 one  character	 too many.  If a correction is
		      found, the corrected file	name is	printed, and the  com-
		      mand  proceeds.  This option is only used	by interactive
		      shells.
	      checkhash
		      If set, bash checks that a command found in the hash ta-
		      ble  exists  before  trying  to execute it.  If a	hashed
		      command no longer	exists,	a normal path search  is  per-
		      formed.
	      checkjobs
		      If set, bash lists the status of any stopped and running
		      jobs before exiting an interactive shell.	 If  any  jobs
		      are running, this	causes the exit	to be deferred until a
		      second exit is attempted without an intervening  command
		      (see JOB CONTROL above).	The shell always postpones ex-
		      iting if any jobs	are stopped.
	      checkwinsize
		      If set, bash checks the window size after	 each  command
		      and,  if necessary, updates the values of	LINES and COL-
		      UMNS.
	      cmdhist If set, bash attempts to save all	lines of  a  multiple-
		      line  command  in	 the  same history entry.  This	allows
		      easy re-editing of multi-line commands.
	      colonbreakswords
		      If set, and readline is being used, bash will treat : as
		      separating  word	being  completed (see Completing under
		      READLINE above).	This is	enabled	by default.
	      compat31
		      If set, bash changes its behavior	to that	of version 3.1
		      with respect to quoted arguments to the conditional com-
		      mand's =~	operator.
	      compat32
		      If set, bash changes its behavior	to that	of version 3.2
		      with  respect  to	locale-specific	string comparison when
		      using the	conditional command's <	and > operators.
	      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  and
		      the effect of interrupting a command list.
	      dirspell
		      If  set,	bash attempts spelling correction on directory
		      names during word	completion if the directory name  ini-
		      tially supplied does not exist.
	      dotglob If  set, bash includes filenames beginning with a	`.' in
		      the results of pathname expansion.
	      execfail
		      If set, a	non-interactive	shell will not exit if it can-
		      not  execute  the	 file  specified as an argument	to the
		      exec builtin command.  An	 interactive  shell  does  not
		      exit if exec fails.
	      expand_aliases
		      If  set,	aliases	 are expanded as described above under
		      ALIASES.	This option is enabled by default for interac-
		      tive shells.
	      extdebug
		      If  set,	behavior  intended for use by debuggers	is en-
		      abled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name	supplied as an argument.
		      2.     If	the command run	by the DEBUG  trap  returns  a
			     non-zero  value,  the next	command	is skipped and
			     not executed.
		      3.     If	the command run	by the DEBUG  trap  returns  a
			     value  of 2, and the shell	is executing in	a sub-
			     routine (a	shell function or a shell script  exe-
			     cuted by the . or source builtins), a call	to re-
			     turn is simulated.
		      4.     BASH_ARGC and BASH_ARGV are updated as  described
			     in	their descriptions above.
		      5.     Function  tracing	is enabled:  command substitu-
			     tion, shell functions, and	subshells invoked with
			     ( command ) inherit the DEBUG and RETURN traps.
		      6.     Error  tracing is enabled:	 command substitution,
			     shell functions, and  subshells  invoked  with  (
			     command ) inherit the ERROR trap.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      extquote
		      If set, $'string'	and  $"string"	quoting	 is  performed
		      within   ${parameter}   expansions  enclosed  in	double
		      quotes.  This option is enabled by default.
	      failglob
		      If set, patterns which fail to  match  filenames	during
		      pathname expansion result	in an expansion	error.
	      force_fignore
		      If  set,	the  suffixes  specified  by the FIGNORE shell
		      variable cause words to be ignored when performing  word
		      completion even if the ignored words are the only	possi-
		      ble completions.	See SHELL VARIABLES above  for	a  de-
		      scription	 of  FIGNORE.	This  option is	enabled	by de-
		      fault.
	      globstar
		      If set, the pattern ** used in a pathname	expansion con-
		      text will	match a	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.
	      implicitcd
		      If  this	is set,	a directory name typed as a command is
		      treated as a request to change to	that directory.	  This
		      behavior	is  inhibited  in  non-interactive mode	or for
		      command strings with more	than one word.	 Changing  di-
		      rectory  takes  precedence  over	executing a like-named
		      command, but  it	is  done  after	 alias	substitutions.
		      Tilde and	variable expansions work as expected.
	      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.
	      lithist If set, and the cmdhist option  is  enabled,  multi-line
		      commands are saved to the	history	with embedded newlines
		      rather than using	semicolon separators where possible.
	      login_shell
		      The shell	sets this option if it is started as  a	 login
		      shell  (see  INVOCATION  above).	 The  value may	not be
		      changed.
	      mailwarn
		      If set, and a file that bash is checking	for  mail  has
		      been  accessed  since  the last time it was checked, the
		      message ``The mail in mailfile has been read''  is  dis-
		      played.
	      no_empty_cmd_completion
		      If  set,	and  readline is being used, bash will not at-
		      tempt to search the PATH for possible  completions  when
		      completion is attempted on an empty line.
	      nocaseglob
		      If  set,	bash  matches  filenames in a case-insensitive
		      fashion when performing pathname expansion (see Pathname
		      Expansion	above).
	      nocasematch
		      If  set,	bash  matches  patterns	 in a case-insensitive
		      fashion when performing matching while executing case or
		      [[ conditional commands.
	      nullglob
		      If  set,	bash allows patterns which match no files (see
		      Pathname Expansion above)	to expand to  a	 null  string,
		      rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Pro-
		      grammable	Completion above) are enabled.	This option is
		      enabled by default.
	      promptvars
		      If set, prompt strings undergo parameter expansion, com-
		      mand substitution, arithmetic expansion, and  quote  re-
		      moval  after  being  expanded  as	described in PROMPTING
		      above.  This option is enabled by	default.
	      restricted_shell
		      The shell	sets this option  if  it  is  started  in  re-
		      stricted	mode  (see RESTRICTED SHELL below).  The value
		      may not be changed.  This	is not reset when the  startup
		      files  are  executed, allowing the startup files to dis-
		      cover whether or not a shell is restricted.
	      shift_verbose
		      If set, the shift	builtin	prints an error	 message  when
		      the shift	count exceeds the number of positional parame-
		      ters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to
		      find  the	 directory  containing the file	supplied as an
		      argument.	 This option is	enabled	by default.
	      xpg_echo
		      If set, the echo builtin	expands	 backslash-escape  se-
		      quences by default.
       suspend [-f]
	      Suspend  the execution of	this shell until it receives a SIGCONT
	      signal.  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 or 1 depending on the evaluation	of the
	      conditional expression expr.  Each operator and operand must  be
	      a	 separate argument.  Expressions are composed of the primaries
	      described	above under CONDITIONAL	EXPRESSIONS.   test  does  not
	      accept any options, nor does it accept and ignore	an argument of
	      -- as signifying the end of options.

	      Expressions may  be  combined  using  the	 following  operators,
	      listed  in  decreasing  order of precedence.  The	evaluation de-
	      pends on the number of arguments;	see below.
	      !	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
		     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.

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

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

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

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

	      Signals ignored upon entry to the	shell cannot be	trapped	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, not necessarily the
	      file that	appears	first in PATH.	If the -a option is used, type
	      prints  all of the places	that contain an	executable named name.
	      This includes aliases and	functions, if and only if the  -p  op-
	      tion is not also used.  The table	of hashed commands is not con-
	      sulted when using	-a.  The -f option suppresses  shell  function
	      lookup,  as  with	the command builtin.  type returns true	if all
	      of the arguments are found, false	if any are not found.

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

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

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

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

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

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

RESTRICTED SHELL
       If bash is started with the name	rbash, or the -r option	is supplied at
       invocation,  the	 shell becomes restricted.  A restricted shell is used
       to set up an environment	more controlled	than the standard  shell.   It
       behaves	identically  to	bash with the exception	that the following are
       disallowed or not performed:

       o      changing directories with	cd

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

       o      specifying command names containing /

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

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

       o      importing	function definitions from  the	shell  environment  at
	      startup

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

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

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

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

       o      Using  the  enable  builtin  command  to	enable	disabled shell
	      builtins

       o      specifying the -p	option to the command builtin command

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

       These restrictions are enforced after any startup files are read.

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

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

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

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

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

BUG REPORTS
       If you find a bug in bash, you should report it.	 But first, you	should
       make  sure  that	 it really is a	bug, and that it appears in the	latest
       version	of  bash.   The	 latest	 version  is  always  available	  from
       ftp://ftp.gnu.org/pub/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@po.cwru.edu.

BUGS
       It's too	big and	too slow.

       There are some subtle differences between bash and traditional versions
       of sh, mostly because of	the POSIX specification.

       Aliases are confusing in	some uses.

       Shell builtin commands and functions are	not stoppable/restartable.

       Compound	commands and command sequences of the form `a ;	b ; c' are not
       handled	gracefully  when  process  suspension  is  attempted.	When a
       process is stopped, the shell immediately executes the next command  in
       the  sequence.	It  suffices to	place the sequence of commands between
       parentheses to force it into a subshell,	which  may  be	stopped	 as  a
       unit.

       Array variables may not (yet) be	exported.

       There may be only one active coprocess at a time.

GNU Bash-4.1		       2009 December 29			       BASH(1)

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

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