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BASH(1)								       BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2005 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
       description of the set builtin command, bash interprets	the  following
       options when it is invoked:

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

       Bash  also  interprets  a  number  of  multi-character  options.	 These
       options must appear on the command  line	 before	 the  single-character
       options 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
	      INVOCATION 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
	      below).

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

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

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

       --rpm-requires
	      Produce the list of files	that are required for the shell	script
	      to run.  This implies '-n' and is	subject	to  the	 same  limita-
	      tions  as	 compile  time	error checking checking; Backticks, []
	      tests,  and evals	are not	parsed so  some	 dependencies  may  be
	      missed.

       --verbose
	      Equivalent to  -v.

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

ARGUMENTS
       If arguments remain after option	processing, and	neither	the -c nor the
       -s  option  has	been supplied, the first argument is assumed to	be the
       name of a file containing shell commands.  If bash is invoked  in  this
       fashion,	 $0 is set to the name of the file, and	the positional parame-
       ters are	set to the remaining arguments.	 Bash reads and	executes  com-
       mands  from this	file, then exits.  Bash's exit status is the exit sta-
       tus of the last command executed	in the script.	 If  no	 commands  are
       executed,  the  exit status is 0.  An attempt is	first made to open the
       file in the current directory, and, if no file is found,	then the shell
       searches	the directories	in 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
       example,	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
       behavior	of historical versions of sh as	 closely  as  possible,	 while
       conforming  to the POSIX	standard as well.  When	invoked	as an interac-
       tive login shell, or a non-interactive shell with the  --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
       inhibit	this  behavior.	 When invoked as an interactive	shell with the
       name sh,	bash looks for the variable ENV, expands its value  if	it  is
       defined,	 and uses the expanded value as	the name of a file to read and
       execute.	 Since a shell invoked as sh does not attempt to read and exe-
       cute  commands from any other startup files, the	--rcfile option	has no
       effect.	A non-interactive shell	invoked	with  the  name	 sh  does  not
       attempt	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	by  the	 remote	 shell
       daemon,	usually	 rshd.	If bash	determines it is being run by rshd, 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 allow them to be	specified.

       If the shell is started with the	effective user (group) id not equal to
       the real	user (group) id, and the -p option is not supplied, no startup
       files are read, shell functions are not inherited from the environment,
       the  SHELLOPTS  variable, if it appears in the environment, is 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
       arguments 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 the char-
       acter |.	 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).

       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.

       The control operators &&	and || denote AND lists	and OR lists,  respec-
       tively.	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
	      effect  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.

       ((expression))
	      The expression is	evaluated according  to	 the  rules  described
	      below  under ARITHMETIC EVALUATION.  If the value	of the expres-
	      sion is non-zero,	the return status is 0;	otherwise  the	return
	      status is	1.  This is exactly equivalent to 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  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.	Substrings  matched  by	 parenthesized
	      subexpressions  within  the  regular expression are saved	in the
	      array variable BASH_REMATCH.  The	element	of  BASH_REMATCH  with
	      index 0 is the portion of	the string matching the	entire regular
	      expression.  The element of BASH_REMATCH with  index  n  is  the
	      portion  of the string matching the nth parenthesized subexpres-
	      sion.

	      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
	      parameter	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
	      error,  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 stan-
	      dard 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  dis-
	      played 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
	      expanded	using  tilde  expansion, parameter and variable	expan-
	      sion, arithmetic	substitution,  command	substitution,  process
	      substitution  and	 quote	removal.   Each	 pattern  examined  is
	      expanded using tilde expansion, parameter	 and  variable	expan-
	      sion, arithmetic substitution, command substitution, and process
	      substitution.  If	the shell option nocasematch is	 enabled,  the
	      match  is	 performed  without  regard  to	the case of alphabetic
	      characters.  When	a match	is found, the  corresponding  list  is
	      executed.	  After	 the  first  match,  no	subsequent matches are
	      attempted.  The exit status is zero if no	pattern	matches.  Oth-
	      erwise,  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.

   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
       itself  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     an	escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal	tab
	      \v     vertical tab
	      \\     backslash
	      \'     single 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 ($)	will cause the
       string to be translated according to the	current	locale.	 If  the  cur-
       rent  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,
       export, 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
       unset (as it is when using =), and new values are appended to the array
       beginning at one	greater	than the array's maximum index.	 When  applied
       to  a  string-valued  variable,	value  is expanded and appended	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$2c...", where c is the first	character of the value
	      of the IFS variable.  If IFS is unset, the parameters are	 sepa-
	      rated  by	 spaces.   If  IFS  is null, the parameters are	joined
	      without intervening separators.
       @      Expands to the positional	parameters, starting from  one.	  When
	      the  expansion  occurs  within  double  quotes,  each  parameter
	      expands to a separate word.  That	is, "$@" 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 status of the most	recently  executed  foreground
	      pipeline.
       -      Expands  to  the	current	option flags as	specified upon invoca-
	      tion, by the set builtin command,	or  those  set	by  the	 shell
	      itself (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
	      argument	to the previous	command, after expansion.  Also	set to
	      the full pathname	used  to  invoke  each	command	 executed  and
	      placed in	the environment	exported to that command.  When	check-
	      ing mail,	this parameter holds the name of the  mail  file  cur-
	      rently being checked.

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands  to  the	full file name used to invoke this instance of
	      bash.
       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
	      option 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
	      below)
       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
	      ${FUNCNAME[$ifP]}	was called.   The  corresponding  source  file
	      name  is	${BASH_SOURCE[$i]}.   Use LINENO to obtain the current
	      line number.
       BASH_REMATCH
	      An array variable	whose members are assigned by  the  =~	binary
	      operator	to the [[ conditional command.	The element with index
	      0	is the portion of  the	string	matching  the  entire  regular
	      expression.   The	 element  with	index  n is the	portion	of the
	      string matching the nth parenthesized subexpression.  This vari-
	      able 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_LINE
	      The  current  command  line.  This variable is available only in
	      shell functions  and  external  commands	invoked	 by  the  pro-
	      grammable	 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  pro-
	      grammable	 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 words	are  split  on
	      shell  metacharacters  as	 the shell parser would	separate them.
	      This variable is available only in shell	functions  invoked  by
	      the programmable completion facilities (see Programmable Comple-
	      tion 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
	      unset,  it  loses	 its  special properties, even if it is	subse-
	      quently 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
	      reset.

       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
       assigns 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
	      directories specified by the cd  command.	  A  sample  value  is
	      ".:~:/usr".
       COLUMNS
	      Used  by	the  select  builtin command to	determine the terminal
	      width when printing selection  lists.   Automatically  set  upon
	      receipt of a SIGWINCH.
       COMPREPLY
	      An array variable	from which bash	reads the possible completions
	      generated	by a shell function invoked by the  programmable  com-
	      pletion facility (see Programmable Completion below).
       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
	      ignorespace,  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
	      exits.
       HISTFILESIZE
	      The maximum number of lines contained in the history file.  When
	      this variable is assigned	a value, the  history  file  is	 trun-
	      cated,  if necessary, 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
	      anchored at the beginning	of the line and	must  match  the  com-
	      plete  line  (no	implicit  `*'  is  appended).  Each pattern is
	      tested against the line after the	checks specified  by  HISTCON-
	      TROL  are	 applied.   In	addition  to  the normal shell pattern
	      matching characters, `&' matches the previous history line.  `&'
	      may  be  escaped	using  a  backslash;  the backslash is removed
	      before attempting	a match.  The second and subsequent lines of a
	      multi-line compound command are not tested, and are added	to the
	      history regardless of the	value of 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.
       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
	      attempted	 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,	bash attempts to read /etc/hosts to obtain the list of
	      possible hostname	completions.   When  HOSTFILE  is  unset,  the
	      hostname list is cleared.
       IFS    The  Internal  Field  Separator  that is used for	word splitting
	      after 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
	      default 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
	      sequences	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
	      receipt 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
	      default  is  60 seconds.	When it	is time	to check for mail, the
	      shell does so before displaying the  primary  prompt.   If  this
	      variable	is  unset,  or	set  to	 a  value that is not a	number
	      greater than or equal to zero, the shell disables	mail checking.
       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.
       PS1    The  value  of  this parameter is	expanded (see PROMPTING	below)
	      and used as the primary prompt string.   The  default  value  is
	      ``\s-\v\$	''.
       PS2    The  value of this parameter is expanded as with PS1 and used as
	      the secondary prompt string.  The	default	is ``> ''.
       PS3    The value	of this	parameter is used as the prompt	for the	select
	      command (see SHELL GRAMMAR above).
       PS4    The  value  of  this  parameter  is expanded as with PS1 and the
	      value is printed before each command  bash  displays  during  an
	      execution	 trace.	 The first character of	PS4 is replicated mul-
	      tiple times, as necessary, to indicate multiple levels of	 indi-
	      rection.	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
	      default 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
	      issuing  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	array  variables.  Any variable	may be
       used as an 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 contiguously.  Arrays  are  indexed
       using integers and are zero-based.

       An  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	array,	use  declare  -a  name
       (see SHELL BUILTIN COMMANDS below).  declare -a name[subscript] is also
       accepted; the subscript is ignored.  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.	Only string is required.  If the optional brackets and
       subscript  are supplied,	that index is assigned to; otherwise the index
       of the element assigned is the last index assigned to by	the  statement
       plus  one.   Indexing  starts at	zero.  This syntax is also accepted by
       the declare builtin.  Individual	array  elements	 may  be  assigned  to
       using the name[subscript]=value syntax introduced 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
       expansion of the	first parameter	is joined with the beginning  part  of
       the  original  word,  and the expansion of the last parameter is	joined
       with the	last part of the original word.	  This	is  analogous  to  the
       expansion  of  the  special  parameters * and @ (see Special Parameters
       above).	${#name[subscript]}  expands  to  the  length  of  ${name[sub-
       script]}.   If subscript	is * or	@, the expansion is the	number of ele-
       ments in	the array.  Referencing	an array variable without a  subscript
       is equivalent to	referencing element zero.

       The  unset  builtin  is	used to	destroy	arrays.	 unset name[subscript]
       destroys	the array element at index subscript.  Care must be  taken  to
       avoid unwanted side effects caused by filename generation.  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 array.  The read builtin accepts a -a	 option	 to  assign  a
       list  of	 words	read from the standard input to	an array.  The set and
       declare builtins	display	array values in	a way that allows them	to  be
       reused as assignments.

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

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

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

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

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

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

       A  sequence  expression takes the form {x..y}, where x and y are	either
       integers	or single characters.  When integers are supplied, the expres-
       sion  expands  to each number between x and y, inclusive.  When charac-
       ters are	supplied, the expression expands  to  each  character  lexico-
       graphically between x and y, inclusive.	Note that both x and y must be
       of the same type.

       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
       expression.   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
       replaces	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
       embedded	 arithmetic  expansion,	 command  substitution,	 or  parameter
       expansion.

       ${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	 vari-
       able  formed  from  the	rest of	parameter as the name of the variable;
       this variable is	then expanded and that value is	used in	 the  rest  of
       the  substitution,  rather than the value of parameter itself.  This is
       known as	indirect expansion.  The exceptions to this are	the expansions
       of  ${!prefix*} and ${!name[@]} described below.	 The exclamation point
       must immediately	follow the left	brace in order to  introduce  indirec-
       tion.

       In each of the cases below, word	is subject to tilde expansion, parame-
       ter expansion, command substitution, and	 arithmetic  expansion.	  When
       not  performing substring expansion, bash tests for a parameter that is
       unset or	null; omitting the colon results in a test only	for a  parame-
       ter 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
	      expansion	of word	is assigned to parameter.  The value of	param-
	      eter  is	then  substituted.   Positional	parameters and special
	      parameters 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
	      parameter	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
	      beginning	at offset.  If parameter is an array name indexed by @
	      or  *,  the  result is the length	members	of the array beginning
	      with ${parameter[offset]}.  A negative offset is taken  relative
	      to  one  greater	than the maximum index of the specified	array.
	      Note that	a negative offset must be separated from the colon  by
	      at  least	 one  space to avoid being confused with the :-	expan-
	      sion.  Substring indexing	is zero-based  unless  the  positional
	      parameters are used, in which case the indexing starts at	1.

       ${!prefix*}
       ${!prefix@}
	      Expands to the names of variables	whose names begin with prefix,
	      separated	by the first character of the IFS special variable.

       ${!name[@]}
       ${!name[*]}
	      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}
	      The length in characters of the value of	parameter  is  substi-
	      tuted.   If  parameter  is  * or @, the value substituted	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}
	      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 pattern (the ``##''	case) deleted.
	      If parameter is @	or *, the pattern removal 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 pattern removal operation is  applied  to  each
	      member  of the array in turn, and	the expansion is the resultant
	      list.

       ${parameter%word}
       ${parameter%%word}
	      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 pat-
	      tern (the	``%'' case)  or	 the  longest  matching	 pattern  (the
	      ``%%''  case)  deleted.	If  parameter  is  @ or	*, the pattern
	      removal 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  pattern  removal
	      operation	 is  applied  to each member of	the array in turn, and
	      the expansion is the resultant list.

       ${parameter/pattern/string}
	      The pattern is expanded to produce a pattern just	as in pathname
	      expansion.   Parameter is	expanded and the longest match of pat-
	      tern against its value is	replaced  with	string.	  If  Ipattern
	      begins  with /, all matches of pattern are replaced with string.
	      Normally only the	first match is replaced.   If  pattern	begins
	      with  #, it must match at	the beginning of the expanded value of
	      parameter.  If pattern begins with %, it must match at  the  end
	      of  the expanded value of	parameter.  If string is null, matches
	      of pattern are deleted and the / following pattern may be	 omit-
	      ted.   If	 parameter  is	@  or *, the substitution operation is
	      applied to each positional parameter in turn, and	the  expansion
	      is  the  resultant list.	If parameter is	an array variable sub-
	      scripted with @ or *, the	substitution 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
       tokens in the expression	undergo	parameter expansion, string expansion,
       command substitution, and quote removal.	 Arithmetic expansions may  be
       nested.

       The  evaluation	is performed according to the rules listed below under
       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  any  sequence  of IFS characters 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	white-
       space, along with any adjacent IFS whitespace  characters,  delimits  a
       field.	A  sequence  of	IFS whitespace characters is also treated as a
       delimiter.  If the value	of IFS is null,	no word	splitting occurs.

       Explicit	null arguments ("" or '')  are	retained.   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 dis-
       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
       option is set, and no matches are found,	an error  message  is  printed
       and  the	 command  is  not executed.  If	the shell option nocaseglob is
       enabled,	the match is performed without regard to the  case  of	alpha-
       betic  characters.   When a pattern is used for pathname	expansion, the
       character ``.''	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	explicitly.   In  other	 cases,	 the  ``.''   character	is not
       treated specially.  See the description	of  shopt  below  under	 SHELL
       BUILTIN	COMMANDS  for a	description of the nocaseglob, nullglob, fail-
       glob, 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.
       ?      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.

       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
       expands to more than one	word, bash reports an error.

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 >	dirlist

       directs	only the standard output to file dirlist, because the standard
       error was duplicated as standard	output before the standard output  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
       expansion 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
       results	from  the expansion of word to be opened for appending 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.

       The general format for appending	output is:

	      [n]>>word

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

       There  are  two	formats	 for  redirecting standard output and standard
       error:

	      &>word
       and
	      >&word

       Of the two forms, the first is preferred.  This is semantically equiva-
       lent 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  word  (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
       allows  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
       descriptor open for input, a redirection	error occurs.  If word	evalu-
       ates  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
       before  executing  any  of  the	commands  on  that  line.  Aliases are
       expanded	when a command is read,	not when it is	executed.   Therefore,
       an  alias definition appearing on the same line as another command does
       not take	effect until the next line of input  is	 read.	 The  commands
       following the alias definition on that line are not affected by the new
       alias.  This behavior is	also an	issue  when  functions	are  executed.
       Aliases	are  expanded when a function definition is read, not when the
       function	is executed, because a function	definition is  itself  a  com-
       pound command.  As a consequence, aliases defined in a function are not
       available until after that function is executed.	 To  be	 safe,	always
       put  alias definitions on a separate line, and do not use alias in com-
       pound 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
       interpret  them	(contrast  this	with the execution of a	shell script).
       When a function is executed, the	arguments to the function  become  the
       positional parameters during its	execution.  The	special	parameter # 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 between a function	and its	caller
       with the	exception that the DEBUG and RETURN traps (see the description
       of  the trap builtin under SHELL	BUILTIN	COMMANDS below)	are not	inher-
       ited 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	 func-
       tions inherit the DEBUG and RETURN traps).

       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
       before 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
       recursive 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
       order.  If base is less than or equal to	36,  lowercase	and  uppercase
       letters may be used interchangeably to represent	numbers	between	10 and
       35.

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

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.

       -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
	      options 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
	      True if the strings are equal.  =	may be used in place of	== for
	      strict POSIX compliance.

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

       string1 < string2
	      True if string1 sorts before string2  lexicographically  in  the
	      current locale.

       string1 > string2
	      True  if	string1	 sorts	after string2 lexicographically	in the
	      current locale.

       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
       expansions, assignments,	and redirections, from left to right.

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

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

       3.     Redirections are performed as described above under 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
       affect the current shell	environment.  A	redirection error  causes  the
       command to exit with a non-zero status.

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

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
       remember	 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 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
       under 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
       reset to	the values that	the shell inherited from its parent at invoca-
       tion.  Builtin commands that are	invoked	as part	of a pipeline are also
       executed	in a subshell environment.  Changes made to the	subshell envi-
       ronment cannot affect the shell's execution environment.

       If  a  command  is  followed  by	a & and	job control is not active, the
       default standard	input for the command is  the  empty  file  /dev/null.
       Otherwise,  the	invoked	 command  inherits the file descriptors	of the
       calling 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
       invocation, 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
       declare -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,
       replacing  the  old.  The environment inherited by any executed command
       consists	of the shell's initial environment, whose values may be	 modi-
       fied  in	 the  shell, less any pairs removed by the 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
       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
       returns	a status of 127.  If a command is found	but is not executable,
       the return status is 126.

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

       Shell  builtin  commands	return a status	of 0 (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,
       unless 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
       ignores 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
       effect,	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
       using 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
       execution of processes and continue (resume) their execution at a later
       point.  A user typically	 employs  this	facility  via  an  interactive
       interface supplied jointly by the system's terminal driver and 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
       write to	the terminal.  Background processes which attempt to read from
       (write to) the terminal are sent	a SIGTTIN (SIGTTOU) signal by the ter-
       minal 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
       returned	 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 name.  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	 exam-
       ple, %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 error.  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	 back-
       ground.	 The  previous	job may	be referenced using %-.	 When there is
       the current job only, %-	refers to the shell's notion  of  the  current
       job.   In  output pertaining to jobs (e.g., the output of the jobs com-
       mand), the current job is always	flagged	with a +, and the previous job
       with  a	-.   A	single % (with no accompanying job specification) 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
       exits.

       If an attempt to	exit bash is made while	jobs are  stopped,  the	 shell
       prints a	warning	message.  The jobs command may then be used to inspect
       their status.  If a second attempt to exit is made without an interven-
       ing  command, the shell does not	print another warning, and the 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
		     inserted 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
	      \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
       below),	while  the  command  number is the position in the sequence of
       commands	executed during	the current shell session.  After  the	string
       is  decoded,  it	is expanded via	parameter expansion, command substitu-
       tion, arithmetic	expansion, and quote removal, subject to the value  of
       the  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.
       By default, the line editing commands are similar to those of emacs.  A
       vi-style	 line  editing	interface is also available.  To turn off line
       editing after the shell is running, use the +o emacs or +o  vi  options
       to the set builtin (see SHELL BUILTIN COMMANDS below).

   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
       ~/.inputrc.   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-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.
       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
	      arrow keys.
       expand-tilde (Off)
	      If set  to  on,  tilde  expansion	 is  performed	when  readline
	      attempts 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.
       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),
	      regardless 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-directories).
       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.
       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
	      instead of ringing the bell.
       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
		     instance, 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
		     library 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).
       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
	      inserts 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
	      exactly  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
	      EXPANSION	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 $FCEDIT,
	      $EDITOR, 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
	      argument,	uppercase the previous word, but do not	move point.
       downcase-word (M-l)
	      Lowercase	the current (or	 following)  word.   With  a  negative
	      argument,	lowercase the previous word, but do not	move point.
       capitalize-word (M-c)
	      Capitalize  the  current	(or  following)	word.  With a negative
	      argument,	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.
       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
	      numeric argument,	but is otherwise ignored.  As a	special	 case,
	      if  this	command	is immediately followed	by a character that is
	      neither a	digit or minus sign, the argument count	for  the  next
	      command  is multiplied by	four.  The argument count is initially
	      one, so executing	this function the first	time makes  the	 argu-
	      ment count four, a second	time makes the argument	count sixteen,
	      and so on.

   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 $), username (if the text begins with	 ~),  hostname
	      (if  the	text begins with @), or	command	(including aliases and
	      functions) in turn.  If none of these produces a match, filename
	      completion is attempted.
       possible-completions (M-?)
	      List the possible	completions of the text	before point.
       insert-completions (M-*)
	      Insert  all completions of the text before point that would have
	      been generated by	possible-completions.
       menu-complete
	      Similar to complete, but replaces	the word to be completed  with
	      a	 single	match from the list of possible	completions.  Repeated
	      execution	of menu-complete steps through the  list  of  possible
	      completions,  inserting  each  match in turn.  At	the end	of the
	      list of completions, the bell is rung (subject to	the setting of
	      bell-style) and the original text	is restored.  An argument of n
	      moves n positions	forward	in the list  of	 matches;  a  negative
	      argument	may  be	 used to move backward through the list.  This
	      command is intended to be	 bound	to  TAB,  but  is  unbound  by
	      default.
       delete-char-or-list
	      Deletes  the  character under the	cursor if not at the beginning
	      or end of	the line (like delete-char).  If at  the  end  of  the
	      line, behaves identically	to possible-completions.  This command
	      is unbound by default.
       complete-filename (M-/)
	      Attempt filename completion on the text before point.
       possible-filename-completions (C-x /)
	      List the possible	completions of the text	before point, treating
	      it as a filename.
       complete-username (M-~)
	      Attempt  completion  on  the text	before point, treating it as a
	      username.
       possible-username-completions (C-x ~)
	      List the possible	completions of the text	before point, treating
	      it as a username.
       complete-variable (M-$)
	      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.
       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.
       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
	      removed, the line	will be	executed by the	shell.
       glob-complete-word (M-g)
	      The  word	 before	 point	is  treated  as	a pattern for pathname
	      expansion, with an asterisk implicitly appended.	 This  pattern
	      is  used	to generate a list of matching file names for possible
	      completions.
       glob-expand-word	(C-x *)
	      The word before point is	treated	 as  a	pattern	 for  pathname
	      expansion,  and  the  list  of  matching file names is inserted,
	      replacing	the word.  If  a  numeric  argument  is	 supplied,  an
	      asterisk is appended before pathname expansion.
       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  pro-
       grammable completion facilities are invoked.

       First,  the command name	is identified.	If a compspec has been defined
       for that	command, the compspec is used to generate the list of possible
       completions  for	 the  word.  If	the command word is a full pathname, a
       compspec	for the	full pathname is searched for first.  If  no  compspec
       is  found  for the full pathname, an attempt is made to find a compspec
       for the portion following the final slash.

       Once a compspec has been	found, it is used  to  generate	 the  list  of
       matching	 words.	  If a compspec	is not found, the default 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 filename expansion pattern to	the -G
       option 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  and  COMP_POINT	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
       defined,	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.

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 an	inter-
       active  shell  exits, the last $HISTSIZE	lines are copied from the his-
       tory 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	 over-
       written.	  If  HISTFILE is unset, or if the history file	is unwritable,
       the history is not saved.  After	saving the history, the	 history  file
       is  truncated to	contain	no more	than HISTFILESIZE lines.  If HISTFILE-
       SIZE 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
       manipulate  the	history	file.  When using command-line editing,	search
       commands	are available in each editing mode that	provide	access to  the
       history list.

       The  shell  allows control over which commands are saved	on the history
       list.  The 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
       options.

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
       default.	  Only	backslash  (\) and single quotes can quote the history
       expansion character.

       Several characters inhibit history expansion if found immediately  fol-
       lowing  the history expansion character,	even if	it is unquoted:	space,
       tab, newline, carriage return, and =.  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
       option is enabled (see the description of the shopt builtin), and read-
       line 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 sub-
       stitution will be reloaded into the readline editing buffer for correc-
       tion.   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).

   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
	      delimiter	 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.	  For  example,	 the  :, true, false, and test builtins	do not
       accept options.
       : [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
	      environment  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
	      positional parameters are	unchanged.  The	return status  is  the
	      status  of  the  last  command exited within the script (0 if no
	      commands are executed), and false	if 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
	      returns 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
	      appear  in  .inputrc, but	each binding or	command	must be	passed
	      as a separate argument; e.g.,  '"\C-x\C-r":  re-read-init-file'.
	      Options, if supplied, have the following meanings:
	      -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.
	      -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.
	      -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.
	      -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
		     entered.

	      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
	      exited.  The return value	is non-zero when n is <= 0; Otherwise,
	      break returns 0 value.

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

       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
	      option  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.

       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.

       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
	      option 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
	      facilities, while	available, will	not have useful	values.

	      The matches will be generated in the same	way  as	 if  the  pro-
	      grammable	 completion  code  had	generated them directly	from a
	      completion specification with the	same flags.  If	word is	speci-
	      fied, 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] [-A action] [-G globpat]  [-W
       wordlist] [-P prefix] [-S suffix]
	      [-X filterpat] [-F function] [-C command]	name [name ...]
       complete	-pr [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  process  of	applying  these	completion specifications when
	      word completion is  attempted  is	 described  above  under  Pro-
	      grammable	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 or suppressing trailing spaces).  Intended
			      to be used with shell functions.
		      nospace Tell   readline  not  to	append	a  space  (the
			      default) to words	completed at the  end  of  the
			      line.
		      plusdirs
			      After  any  matches  defined by the compspec are
			      generated,   directory   name   completion    is
			      attempted	 and  any  matches  are	 added	to the
			      results of the other actions.
	      -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  filename  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  filename  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.

       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
	      enclosing	 loops,	 the  last  enclosing  loop (the ``top-level''
	      loop) is resumed.	 When continue is executed inside of loop, the
	      return  value  is	 non-zero  when	n is <=	0; Otherwise, continue
	      returns 0	value.	When continue is executed outside of loop, the
	      return value is 0.

       declare [-afFirtx] [-p] [name[=value] ...]
       typeset [-afFirtx] [-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, additional options are ignored.  The  -F  option  inhibits
	      the  display of function definitions; only the function name and
	      attributes are printed.  If the extdebug shell option is enabled
	      using  shopt,  the  source  file	name and line number where the
	      function is defined  are	displayed  as  well.   The  -F	option
	      implies  -f.  The	following options can be used to restrict out-
	      put to variables with the	specified attribute or to  give	 vari-
	      ables attributes:
	      -a     Each name is an array variable (see Arrays	above).
	      -f     Use function names	only.
	      -i     The variable is treated as	an integer; arithmetic evalua-
		     tion (see ARITHMETIC EVALUATION ) is performed  when  the
		     variable is assigned a value.
	      -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
		     inherit  the  DEBUG  and  RETURN  traps  from the calling
		     shell.  The trace attribute has no	 special  meaning  for
		     variables.
	      -x     Mark  names  for  export  to  subsequent commands via the
		     environment.

	      Using `+'	instead	of `-' turns off the attribute	instead,  with
	      the  exception that +a may not be	used to	destroy	an array vari-
	      able.  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 variable	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	 read-
	      only  status for a readonly variable, an attempt is made to turn
	      off array	status for an array variable, or an attempt is made to
	      display a	non-existent function with -f.

       dirs [-clpv] [+n] [-n]
	      Without  options,	 displays  the	list  of  currently remembered
	      directories.  The	default	display	 is  on	 a  single  line  with
	      directory	 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
		     entries.
	      -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
	      active jobs.  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 job-
	      spec argument restricts operation	to running jobs.   The	return
	      value is 0 unless	a jobspec does not specify a valid job.

       echo [-neE] [arg	...]
	      Output  the  args,  separated  by	spaces,	followed by a newline.
	      The return status	is 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
	      interprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress trailing newline
	      \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 [-adnps] [-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
	      enabled.	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 arg passed to command.	 This is what login(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 cannot 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  can-
	      not  be executed.	 If command is not specified, any redirections
	      take effect in the current shell,	and the	return	status	is  0.
	      If there is a redirection	error, the return status is 1.

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

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

       fc [-e ename] [-nlr] [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
	      beginning	with ``cc'' and	typing ``r'' re-executes the last com-
	      mand.

	      If  the  first  form  is	used,  the return value	is 0 unless an
	      invalid option is	encountered or 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
	      expected	to have	an argument, which should be separated from it
	      by white space.  The colon and question mark characters may  not
	      be  used as option characters.  Each time	it is invoked, 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
	      option requires an argument, getopts places that	argument  into
	      the  variable OPTARG.  The shell does not	reset OPTIND automati-
	      cally; it	must be	 manually  reset  between  multiple  calls  to
	      getopts within the same shell invocation if a new	set of parame-
	      ters is to be used.

	      When the end of options is encountered,  getopts	exits  with  a
	      return  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
	      OPTARG 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 [-s] [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.  The -s option restricts the  information
	      displayed	 to  a	short  usage synopsis.	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
		     appended  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 is set, the	time stamp information associ-
	      ated with	each history entry is written  to  the	history	 file.
	      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 supplied 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
	      executes 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
	      error occurs or an invalid option	is encountered.

       let arg [arg ...]
	      Each arg is an arithmetic	expression to be evaluated (see	ARITH-
	      METIC EVALUATION).  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.

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

	      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] [dir]
       pushd [-n] [+n] [-n]
	      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     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.
	      -n     Suppresses	 the  normal  change  of directory when	adding
		     directories to the	stack,	so  that  only	the  stack  is
		     manipulated.
	      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
	      invalid option is	supplied.

       read [-ers] [-u fd] [-t timeout]	[-a aname] [-p prompt] [-n nchars] [-d
       delim] [name ...]
	      One  line	 is  read  from	 the  standard input, or from the file
	      descriptor 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
		     ignored.
	      -d delim
		     The first character of delim is  used  to	terminate  the
		     input line, rather	than newline.
	      -e     If	the standard input is coming from a terminal, readline
		     (see READLINE above) is used to obtain the	line.
	      -n nchars
		     read returns after	reading	nchars characters rather  than
		     waiting for a complete line of input.
	      -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.	  This
		     option  has  no  effect if	read is	not reading input from
		     the terminal or a pipe.
	      -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
	      encountered, read	times out, or an invalid  file	descriptor  is
	      supplied as the argument to -u.

       readonly	[-apf] [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	arrays.	 If no
	      name  arguments  are  given,  or if the -p option	is supplied, a
	      list of all readonly names is printed.   The  -p	option	causes
	      output  to be displayed in a format that may be reused as	input.
	      If a variable name is followed by	=word, the value of the	 vari-
	      able  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 func-
	      tion.

       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 [--abefhkmnptuvxBCHP] [-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
	      options  are specified, they set or unset	shell attributes.  Any
	      arguments	remaining after	the options are	processed are  treated
	      as  values  for  the  positional parameters and are assigned, in
	      order, to	$1, $2,	...  $n.  Options, if specified, have the fol-
	      lowing 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 simple command (see SHELL GRAMMAR
		      above) exits with	a non-zero status.  The	shell does not
		      exit  if	the  command that fails	is part	of the command
		      list immediately following a  while  or  until  keyword,
		      part  of the test	in an if statement, part of a && or ||
		      list, or if the command's	return value is	being inverted
		      via  !.	A  trap	on ERR,	if set,	is executed before the
		      shell exits.
	      -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
		      ignored 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.
		      errtrace
			      Same as -E.
		      functrace
			      Same as -T.
		      errexit Same as -e.
		      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
			      ``IGNOREEOF=10'' had been	 executed  (see	 Shell
			      Variables	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.
		      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
		      variable,	if it appears in the environment, is  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 supplied, these actions are taken and the
		      effective	user id	is set to the real user	id.  If	the -p
		      option  is supplied at startup, the effective user id is
		      not reset.  Turning this option off causes the effective
		      user  and	group ids to be	set to the real	user and group
		      ids.
	      -t      Exit after reading and executing one command.
	      -u      Treat unset variables as an error	when performing	param-
		      eter  expansion.	 If expansion is attempted on an unset
		      variable,	the shell prints an error message, and,	if not
		      interactive, exits with a	non-zero status.
	      -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
		      executed	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
	      options can also be specified as arguments to an	invocation  of
	      the  shell.  The current set of options may be found in $-.  The
	      return 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
	      unset.   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
	      parameters 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
	      options, the return status is zero unless	an optname  is	not  a
	      valid shell option.

	      The list of shopt	options	is:

	      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.
	      checkwinsize
		      If set, bash checks the window size after	 each  command
		      and,  if necessary, updates the values of	LINES and COL-
		      UMNS.
	      cmdhist If set, bash attempts to save all	lines of  a  multiple-
		      line  command  in	 the  same history entry.  This	allows
		      easy re-editing of multi-line commands.
	      compat31
		      If set, bash changes its behavior	to that	of version 3.1
		      with respect to quoted arguments to the conditional com-
		      mand's =~	operator.
	      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
		      enabled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name	supplied as an argument.
		      2.     If	 the  command  run by the DEBUG	trap returns a
			     non-zero value, the next command is  skipped  and
			     not executed.
		      3.     If	 the  command  run by the DEBUG	trap returns a
			     value of 2, and the shell is executing in a  sub-
			     routine  (a shell function	or a shell script exe-
			     cuted by the . or source  builtins),  a  call  to
			     return 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
		      description of  FIGNORE.	 This  option  is  enabled  by
		      default.
	      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
		      exits, rather than overwriting the file.
	      histreedit
		      If set, and readline is being used, a user is given  the
		      opportunity to re-edit a failed history substitution.
	      histverify
		      If  set, and readline is being used, the results of his-
		      tory substitution	are  not  immediately  passed  to  the
		      shell  parser.   Instead,	 the  resulting	line is	loaded
		      into the readline	editing	buffer,	allowing further modi-
		      fication.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to
		      perform hostname completion when a word containing  a  @
		      is   being  completed  (see  Completing  under  READLINE
		      above).  This is enabled by default.
	      huponexit
		      If set, bash will	send SIGHUP to all jobs	when an	inter-
		      active login shell exits.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word
		      and all remaining	characters on that line	to be  ignored
		      in  an  interactive  shell  (see	COMMENTS above).  This
		      option 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
		      attempt 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
		      removal  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
		      restricted 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
		      sequences	by default.
       suspend [-f]
	      Suspend  the execution of	this shell until it receives a SIGCONT
	      signal.  When the	suspended shell	is a  background  process,  it
	      can  be  restarted by the	fg command. For	more information, read
	      the JOB CONTROL section. The suspend command can not suspend the
	      login shell.  However, when -f option is specified, suspend com-
	      mand can suspend even login  shell.   The	 return	 status	 is  0
	      unless  the shell	is a login shell and -f	is not supplied, or if
	      job control is not enabled.
       test expr
       [ expr ]
	      Return a status of 0 or 1	depending on  the  evaluation  of  the
	      conditional  expression expr.  Each operator and operand must be
	      a	separate argument.  Expressions	are composed of	the  primaries
	      described	 above	under  CONDITIONAL EXPRESSIONS.	 test does not
	      accept any options, nor does it accept and ignore	an argument of
	      -- as signifying the end of options.

	      Expressions  may	be  combined  using  the  following operators,
	      listed in	decreasing order of precedence.
	      !	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.  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.	 Otherwise,  the  expression is	false.
		     The -a and	-o operators are considered  binary  operators
		     in	this case.
	      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
	      receives signal(s) sigspec.  If arg is absent (and  there	 is  a
	      single  sigspec)	or  -,	each  specified	signal is reset	to its
	      original 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 commands associated with each  signal.   The  -l	option
	      causes  the shell	to print a list	of signal names	and their cor-
	      responding numbers.   Each  sigspec  is  either  a  signal  name
	      defined  in  <signal.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	executed 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 ERR,
	      the command arg is executed whenever  a  simple  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	until keyword,
	      part of the test in an if	statement, part	of a &&	or || list, or
	      if  the  command's  return value is being	inverted via !.	 These
	      are the same conditions obeyed by	 the  errexit  option.	 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.	Signals	ignored	upon entry to the shell	cannot
	      be trapped or reset.  Trapped signals that are not being ignored
	      are reset	to their original values in a child process when it is
	      created.	The return status is false if any 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
	      returned.	  If  the  -p  option is used, type either returns the
	      name of the disk file that would be executed if name were	speci-
	      fied as a	command	name, or nothing if ``type -t name'' would not
	      return 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
	      option is	not also used.	The table of hashed  commands  is  not
	      consulted	 when  using -a.  The -f option	suppresses shell func-
	      tion lookup, as with the command builtin.	 type returns true  if
	      any of the arguments are found, false if none are	found.

       ulimit [-SHacdefilmnpqrstuvx [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  once
	      it  is set; a soft limit may be increased	up to the value	of the
	      hard limit.  If neither -H nor -S	is specified,  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,  respectively.   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 interpreted as fol-
	      lows:
	      -a     All current limits	are reported
	      -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 (has	no effect on Linux)
	      -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

	      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  -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
	      unset.   If  -f  is specified, each name refers to a shell func-
	      tion, and	the function definition	is removed.  Each unset	 vari-
	      able  or function	is removed from	the environment	passed to sub-
	      sequent commands.	 If any	of RANDOM, SECONDS,  LINENO,  HISTCMD,
	      FUNCNAME,	GROUPS,	or DIRSTACK are	unset, they lose their special
	      properties, even if they are subsequently	reset.	The exit  sta-
	      tus is true unless a name	is readonly.

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

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

       o      changing directories with	cd

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

       o      specifying command names containing /

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

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

       o      importing	 function  definitions	from  the shell	environment at
	      startup

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

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

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

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

       o      Using the	 enable	 builtin  command  to  enable  disabled	 shell
	      builtins

       o      specifying the -p	option to the command builtin command

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

       These restrictions are enforced after any startup files are read.

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

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

FILES
       /bin/bash
	      The bash executable
       /etc/profile
	      The systemwide initialization file, executed for login shells
       ~/.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@po.cwru.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.

       Commands	 inside	 of  $(...)  command substitution are not parsed until
       substitution is attempted.  This	will delay error reporting until  some
       time after the command is entered.  For example,	unmatched parentheses,
       even inside shell comments, will	result in  error  messages  while  the
       construct is being read.

       Array variables may not (yet) be	exported.

       When  breaking out of multiple loops, if	the outermost loop consists of
       more than one command, the exit status of break and continue is lost.

GNU Bash-3.2		       2006 September 28		       BASH(1)

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

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