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BASH(1)			    General Commands Manual		       BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2005 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 de-
       scription of the	set builtin command, bash interprets the following op-
       tions when it is	invoked:

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

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

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

       --login
	      Equivalent to -l.

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

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

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

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

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

       --verbose
	      Equivalent to  -v.

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

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

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

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

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

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

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

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

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

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

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

       Bash  attempts  to  determine  when it is being run 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  ar-
       guments to the invoked command.

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

   Pipelines
       A pipeline is a sequence	of one or more commands	separated by 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 ef-
	      fect after the command completes.	 The return status is the exit
	      status of	list.

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

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

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

	      When 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 sub-
	      expressions within the regular expression	are saved in the array
	      variable BASH_REMATCH.  The element of BASH_REMATCH with index 0
	      is the portion of	the string matching the	entire regular expres-
	      sion.   The  element of BASH_REMATCH with	index n	is the portion
	      of the string matching the nth parenthesized subexpression.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       Words of	the form $'string' are treated specially.  The word expands to
       string,	with backslash-escaped characters replaced as specified	by the
       ANSI C standard.	 Backslash escape sequences, if	present,  are  decoded
       as follows:
	      \a     alert (bell)
	      \b     backspace
	      \e     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, ex-
       port, readonly, and local builtin commands.

       In the context where an assignment statement is assigning a value to  a
       shell variable or array index, the += operator can be used to append to
       or add to the variable's	previous value.	 When += is applied to a vari-
       able  for  which	the integer attribute has been set, value is evaluated
       as an arithmetic	expression and added to	the variable's current	value,
       which is	also evaluated.	 When += is applied to an array	variable using
       compound	assignment (see	Arrays below), the variable's value is not un-
       set  (as	 it is when using =), and new values are appended to the array
       beginning at one	greater	than the array's maximum index.	 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$2c...", where c is the first	character of the value
	      of the IFS variable.  If IFS is unset, the parameters are	 sepa-
	      rated  by	 spaces.   If  IFS  is null, the parameters are	joined
	      without intervening separators.
       @      Expands to the positional	parameters, starting from  one.	  When
	      the  expansion  occurs  within double quotes, each parameter ex-
	      pands to a separate word.	 That is, "$@" is equivalent  to  "$1"
	      "$2"  ...	  If the double-quoted expansion occurs	within a word,
	      the expansion of the first parameter is joined with  the	begin-
	      ning  part  of  the original word, and the expansion of the last
	      parameter	is joined with the last	part  of  the  original	 word.
	      When  there  are no positional parameters, "$@" and $@ expand to
	      nothing (i.e., they are removed).
       #      Expands to the number of positional parameters in	decimal.
       ?      Expands to the 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  it-
	      self (such as the	-i option).
       $      Expands  to  the	process	ID of the shell.  In a () subshell, it
	      expands to the process ID	of the current	shell,	not  the  sub-
	      shell.
       !      Expands  to  the	process	ID of the most recently	executed back-
	      ground (asynchronous) command.
       0      Expands to the name of the shell or shell	script.	 This  is  set
	      at shell initialization.	If bash	is invoked with	a file of com-
	      mands, $0	is set to the name of that file.  If bash  is  started
	      with  the	 -c option, then $0 is set to the first	argument after
	      the string to be executed, if one	is present.  Otherwise,	it  is
	      set  to  the file	name used to invoke bash, as given by argument
	      zero.
       _      At shell startup,	set to the absolute pathname  used  to	invoke
	      the  shell or shell script being executed	as passed in the envi-
	      ronment or argument list.	 Subsequently, expands to the last ar-
	      gument  to  the  previous	command, after expansion.  Also	set to
	      the full pathname	used  to  invoke  each	command	 executed  and
	      placed in	the environment	exported to that command.  When	check-
	      ing mail,	this parameter holds the name of the  mail  file  cur-
	      rently being checked.

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands  to  the	full file name used to invoke this instance of
	      bash.
       BASH_ARGC
	      An array variable	whose values are the number of	parameters  in
	      each frame of the	current	bash execution call stack.  The	number
	      of parameters to	the  current  subroutine  (shell  function  or
	      script  executed	with  .	or source) is at the top of the	stack.
	      When a subroutine	is executed, the number	of  parameters	passed
	      is pushed	onto BASH_ARGC.	 The shell sets	BASH_ARGC only when in
	      extended debugging mode (see the description of the extdebug op-
	      tion to the shopt	builtin	below)
       BASH_ARGV
	      An  array	 variable containing all of the	parameters in the cur-
	      rent bash	execution call stack.  The final parameter of the last
	      subroutine  call is at the top of	the stack; the first parameter
	      of the initial call is at	the bottom.  When a subroutine is exe-
	      cuted,  the  parameters supplied are pushed onto BASH_ARGV.  The
	      shell sets BASH_ARGV only	when in	extended debugging  mode  (see
	      the  description of the extdebug option to the shopt builtin be-
	      low)
       BASH_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  ex-
	      pression.	 The element with index	n is the portion of the	string
	      matching the nth parenthesized subexpression.  This variable  is
	      read-only.
       BASH_SOURCE
	      An  array	variable whose members are the source filenames	corre-
	      sponding to the elements in the FUNCNAME array variable.
       BASH_SUBSHELL
	      Incremented by one each time a subshell or subshell  environment
	      is spawned.  The initial value is	0.
       BASH_VERSINFO
	      A	readonly array variable	whose members hold version information
	      for this instance	of bash.  The values  assigned	to  the	 array
	      members are as follows:
	      BASH_VERSINFO[0]	      The major	version	number (the release).
	      BASH_VERSINFO[1]	      The minor	version	number (the version).
	      BASH_VERSINFO[2]	      The patch	level.
	      BASH_VERSINFO[3]	      The build	version.
	      BASH_VERSINFO[4]	      The release status (e.g.,	beta1).
	      BASH_VERSINFO[5]	      The value	of MACHTYPE.

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

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

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

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

       COMP_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  un-
	      set, it loses its	special	properties, even if it is subsequently
	      reset.

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

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

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

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

       HOSTNAME
	      Automatically set	to the name of the current host.

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

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

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

       OLDPWD The previous working directory as	set by the cd command.

       OPTARG The  value  of the last option argument processed	by the getopts
	      builtin command (see SHELL BUILTIN COMMANDS below).

       OPTIND The index	of the next argument to	be processed  by  the  getopts
	      builtin command (see SHELL BUILTIN COMMANDS below).

       OSTYPE Automatically  set to a string that describes the	operating sys-
	      tem on which bash	is executing.  The  default  is	 system-depen-
	      dent.

       PIPESTATUS
	      An  array	 variable (see Arrays below) containing	a list of exit
	      status values from the processes in  the	most-recently-executed
	      foreground pipeline (which may contain only a single command).

       PPID   The  process  ID	of the shell's parent.	This variable is read-
	      only.

       PWD    The current working directory as set by the cd command.

       RANDOM Each time	this parameter is referenced, a	random integer between
	      0	and 32767 is generated.	 The sequence of random	numbers	may be
	      initialized by assigning a value to RANDOM.  If RANDOM is	unset,
	      it  loses	its special properties,	even if	it is subsequently re-
	      set.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   Arrays
       Bash  provides  one-dimensional	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  us-
       ing 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 ex-
       pansion of the first parameter is joined	with the beginning part	of the
       original	 word,	and the	expansion of the last parameter	is joined with
       the last	part of	the original word.  This is analogous to the expansion
       of  the	special	 parameters  *	and  @ (see Special Parameters above).
       ${#name[subscript]} expands to the length  of  ${name[subscript]}.   If
       subscript is * or @, the	expansion is the number	of elements in the ar-
       ray.  Referencing an array variable without a subscript	is  equivalent
       to referencing element zero.

       The unset builtin is used to destroy arrays.  unset name[subscript] de-
       stroys the array	element	at index subscript.  Care  must	 be  taken  to
       avoid unwanted side effects caused by 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 ex-
       pression.  Any incorrectly formed brace expansion is left unchanged.  A
       { or , may be quoted with a backslash to	prevent	its  being  considered
       part  of	 a brace expression.  To avoid conflicts with parameter	expan-
       sion, the string	${ is not considered eligible for brace	expansion.

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

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

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

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

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

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

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

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

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

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

       If the first character of parameter is an exclamation point, a level of
       variable	indirection is introduced.  Bash uses the value	of  the	 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 ex-
	      pansion of word is assigned to parameter.	 The value of  parame-
	      ter  is then substituted.	 Positional parameters and special pa-
	      rameters may not be assigned to in this way.
       ${parameter:?word}
	      Display Error if Null or Unset.  If parameter is null or	unset,
	      the  expansion  of  word (or a message to	that effect if word is
	      not present) is written to the standard error and	the shell,  if
	      it is not	interactive, exits.  Otherwise,	the value of parameter
	      is substituted.
       ${parameter:+word}
	      Use Alternate Value.  If parameter is null or unset, nothing  is
	      substituted, otherwise the expansion of word is substituted.
       ${parameter:offset}
       ${parameter:offset:length}
	      Substring	 Expansion.  Expands to	up to length characters	of pa-
	      rameter starting at  the	character  specified  by  offset.   If
	      length  is omitted, expands to the substring of parameter	start-
	      ing at the character specified by	offset.	 length	and offset are
	      arithmetic   expressions	 (see  ARITHMETIC  EVALUATION  below).
	      length must evaluate to a	number greater than or equal to	 zero.
	      If  offset  evaluates  to	 a number less than zero, the value is
	      used as an offset	from the end of	the value  of  parameter.   If
	      parameter	 is  @,	the result is length positional	parameters be-
	      ginning at offset.  If parameter is an 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  in-
	      dices (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 ex-
	      panded 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 re-
	      moval operation is applied to each positional parameter in turn,
	      and the expansion	is the resultant list.	If parameter is	an ar-
	      ray variable subscripted with @ or *, the	pattern	removal	opera-
	      tion is applied to each member of	the array in turn, and the ex-
	      pansion 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 be-
	      gins  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 ap-
	      plied 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 re-
	      sultant list.

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

	      $(command)
       or
	      `command`

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

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

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

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

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

	      $((expression))

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

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

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

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

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

       The shell treats	each character of IFS as a delimiter, and  splits  the
       results of the other expansions into words on these characters.	If IFS
       is unset, or its	value is exactly <space><tab><newline>,	 the  default,
       then  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 op-
       tion is set, and	no matches are found, an error message is printed  and
       the  command  is	 not  executed.	 If the	shell option nocaseglob	is en-
       abled, the match	is performed without regard to the case	of  alphabetic
       characters.  When a pattern is used for pathname	expansion, the charac-
       ter ``.''  at the start of a name or immediately	following a slash must
       be  matched  explicitly,	 unless	the shell option dotglob is set.  When
       matching	a pathname, the	slash character	must always be matched explic-
       itly.   In  other cases,	the ``.''  character is	not treated specially.
       See the description of shopt below under	SHELL BUILTIN COMMANDS	for  a
       description  of	the  nocaseglob, nullglob, failglob, and dotglob shell
       options.

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

       Pattern Matching

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

       The special pattern characters have the following meanings:

       *      Matches any string, including the	null string.
       ?      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 ex-
       pands to	more than one word, bash reports an error.

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 >	dirlist

       directs	only the standard output to file dirlist, because the standard
       error was duplicated 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 ex-
       pansion of word to be opened for	writing	on file	descriptor n,  or  the
       standard	output (file descriptor	1) if n	is not specified.  If the file
       does not	exist it is created; if	it does	exist it is truncated to  zero
       size.

       The general format for redirecting output is:

	      [n]>word

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

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

       The general format for appending	output is:

	      [n]>>word

   Redirecting Standard	Output and Standard Error
       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 er-
       ror:

	      &>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  al-
       lows  here-documents  within  shell scripts to be indented in a natural
       fashion.

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

	      <<<word

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

   Duplicating File Descriptors
       The redirection operator

	      [n]<&word

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

       The operator

	      [n]>&word

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

   Moving File Descriptors
       The redirection operator

	      [n]<&digit-

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

       Similarly, the redirection operator

	      [n]>&digit-

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

   Opening File	Descriptors for	Reading	and Writing
       The redirection operator

	      [n]<>word

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

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

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

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

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

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

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

FUNCTIONS
       A  shell	 function,  defined  as	 described  above under	SHELL GRAMMAR,
       stores a	series of commands for later execution.	 When the  name	 of  a
       shell  function	is used	as a simple command name, the list of commands
       associated with that function name is executed.	Functions are executed
       in  the	context	of the current shell; no new process is	created	to in-
       terpret them (contrast this with	the  execution	of  a  shell  script).
       When  a	function is executed, the arguments to the function become the
       positional parameters during its	execution.  The	special	parameter # is
       updated	to reflect the change.	Special	parameter 0 is unchanged.  The
       first element of	the FUNCNAME variable is set to	the name of the	 func-
       tion  while  the	function is executing.	All other aspects of the shell
       execution environment are identical 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 op-
       tion has	been enabled with the set builtin (in which case all functions
       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 be-
       fore  execution	resumes.  When a function completes, the values	of the
       positional parameters and the special parameter # are restored  to  the
       values they had prior to	the function's execution.

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

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

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

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

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

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

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

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

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

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

       string1 == string2
	      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 ex-
       pansions, assignments, and redirections,	from left to right.

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

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

       3.     Redirections are performed as described above under REDIRECTION.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       o      current traps set	by trap

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

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

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

       o      options enabled by shopt

       o      shell aliases defined with alias

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

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

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

       o      the current working directory

       o      the file creation	mode mask

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

JOB CONTROL
       Job control refers to the ability to selectively	stop (suspend) the ex-
       ecution	of  processes and continue (resume) their execution at a later
       point.  A user typically	employs	this facility via an  interactive  in-
       terface supplied	jointly	by the 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 re-
       turned  to  bash.   The user may	then manipulate	the state of this job,
       using the bg command to continue	it in the background, the  fg  command
       to continue it in the foreground, or the	kill command to	kill it.  A ^Z
       takes effect immediately, and has the additional	side effect of causing
       pending output and typeahead to be discarded.

       There are a number of ways to refer to a	job in the shell.  The charac-
       ter % introduces	a job 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 %-.	In output per-
       taining to jobs (e.g., the output of the	jobs command), 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  ex-
       its.

       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 in-
		     serted into the prompt string; an empty format results in
		     a locale-specific time representation.   The  braces  are
		     required
	      \e     an	ASCII escape character (033)
	      \h     the hostname up to	the first `.'
	      \H     the hostname
	      \j     the number	of jobs	currently managed by the shell
	      \l     the basename of the shell's terminal device name
	      \n     newline
	      \r     carriage return
	      \s     the  name	of  the	shell, the basename of $0 (the portion
		     following the final slash)
	      \t     the current time in 24-hour HH:MM:SS format
	      \T     the current time in 12-hour HH:MM:SS format
	      \@     the current time in 12-hour am/pm format
	      \A     the current time in 24-hour HH:MM format
	      \u     the username of the current user
	      \v     the version of bash (e.g.,	2.00)
	      \V     the release of bash, version + patch level	(e.g., 2.00.0)
	      \w     the current working  directory,  with  $HOME  abbreviated
		     with a tilde
	      \W     the basename of the current working directory, with $HOME
		     abbreviated with a	tilde
	      \!     the history number	of this	command
	      \#     the command number	of this	command
	      \$     if	the effective UID is 0,	a #, otherwise a $
	      \nnn   the character corresponding to the	octal number nnn
	      \\     a backslash
	      \[     begin a sequence of non-printing characters, which	 could
		     be	 used  to  embed  a terminal control sequence into the
		     prompt
	      \]     end a sequence of non-printing characters

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

READLINE
       This is the library that	handles	reading	input when using  an  interac-
       tive shell, unless the --noediting option is given at shell invocation.
       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	~/.in-
       putrc.	When  a	program	which uses the readline	library	starts up, the
       initialization file is read, and	the key	 bindings  and	variables  are
       set.   There  are  only	a few basic constructs allowed in the readline
       initialization file.  Blank lines are ignored.  Lines beginning with  a
       #  are  comments.   Lines  beginning with a $ indicate conditional con-
       structs.	 Other lines denote key	bindings and variable settings.

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

       For example, placing

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      set variable-name	value

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

       bell-style (audible)
	      Controls what happens when readline wants	to ring	 the  terminal
	      bell.  If	set to none, readline never rings the bell.  If	set to
	      visible, readline	uses a visible bell if one is  available.   If
	      set to audible, readline attempts	to ring	the terminal's bell.
       bind-tty-special-chars (On)
	      If  set  to On, readline attempts	to bind	the control characters
	      treated specially	by the kernel's	terminal driver	to their read-
	      line equivalents.
       comment-begin (``#'')
	      The  string  that	 is  inserted when the readline	insert-comment
	      command is executed.  This command is bound to M-# in emacs mode
	      and to # in vi command mode.
       completion-ignore-case (Off)
	      If set to	On, readline performs filename matching	and completion
	      in a case-insensitive fashion.
       completion-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 ar-
	      row keys.
       expand-tilde (Off)
	      If  set  to  on,	tilde expansion	is performed when readline at-
	      tempts word completion.
       history-preserve-point (Off)
	      If set to	on, the	history	code attempts to place	point  at  the
	      same  location on	each history line retrieved with previous-his-
	      tory or next-history.
       horizontal-scroll-mode (Off)
	      When set to On, makes readline use a single  line	 for  display,
	      scrolling	the input horizontally on a single screen line when it
	      becomes longer than the screen width rather than wrapping	 to  a
	      new line.
       input-meta (Off)
	      If  set to On, readline will enable eight-bit input (that	is, it
	      will not strip the high bit from the characters it  reads),  re-
	      gardless	of  what the terminal claims it	can support.  The name
	      meta-flag	is a synonym for this variable.
       isearch-terminators (``C-[C-J'')
	      The string of characters that should  terminate  an  incremental
	      search  without  subsequently  executing the character as	a com-
	      mand.  If	this variable has not been given a value, the  charac-
	      ters ESC and C-J will terminate an incremental search.
       keymap (emacs)
	      Set  the current readline	keymap.	 The set of valid keymap names
	      is emacs,	emacs-standard,	emacs-meta,  emacs-ctlx,  vi,  vi-com-
	      mand,  and  vi-insert.  vi is equivalent to vi-command; emacs is
	      equivalent to emacs-standard.  The default value is  emacs;  the
	      value of editing-mode also affects the default keymap.
       mark-directories	(On)
	      If set to	On, completed directory	names have a slash appended.
       mark-modified-lines (Off)
	      If  set  to  On,	history	lines that have	been modified are dis-
	      played with a preceding asterisk (*).
       mark-symlinked-directories (Off)
	      If set to	On, completed names which are symbolic links to	direc-
	      tories  have  a slash appended (subject to the value of mark-di-
	      rectories).
       match-hidden-files (On)
	      This variable, when set to On, causes readline  to  match	 files
	      whose  names  begin  with	 a  `.'	(hidden	files) when performing
	      filename completion, unless the leading `.' is supplied  by  the
	      user in the filename to be completed.
       output-meta (Off)
	      If  set  to On, readline will display characters with the	eighth
	      bit set directly rather than as a	meta-prefixed escape sequence.
       page-completions	(On)
	      If set to	On, readline uses an internal more-like	pager to  dis-
	      play a screenful of possible completions at a time.
       print-completions-horizontally (Off)
	      If  set  to  On,	readline will display completions with matches
	      sorted horizontally in alphabetical order, rather	than down  the
	      screen.
       show-all-if-ambiguous (Off)
	      This  alters  the	 default behavior of the completion functions.
	      If set to	on, words which	have more than one possible completion
	      cause  the  matches  to be listed	immediately instead of ringing
	      the bell.
       show-all-if-unmodified (Off)
	      This alters the default behavior of the completion functions  in
	      a	fashion	similar	to show-all-if-ambiguous.  If set to on, words
	      which have more than one possible	completion without any	possi-
	      ble  partial  completion (the possible completions don't share a
	      common prefix) cause the matches to be  listed  immediately  in-
	      stead of ringing the bell.
       visible-stats (Off)
	      If  set to On, a character denoting a file's type	as reported by
	      stat(2) is appended to the filename when listing	possible  com-
	      pletions.

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

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

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

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

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

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

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

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

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

	      $include	/etc/inputrc

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

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

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

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

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

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

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

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

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

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

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

   Completing
       complete	(TAB)
	      Attempt  to  perform  completion on the text before point.  Bash
	      attempts completion treating the text as a variable (if the text
	      begins  with  $),	username (if the text begins with ~), hostname
	      (if the text begins with @), or command (including  aliases  and
	      functions) in turn.  If none of these produces a match, filename
	      completion is attempted.
       possible-completions (M-?)
	      List the possible	completions of the text	before point.
       insert-completions (M-*)
	      Insert all completions of	the text before	point that would  have
	      been generated by	possible-completions.
       menu-complete
	      Similar  to complete, but	replaces the word to be	completed with
	      a	single match from the list of possible completions.   Repeated
	      execution	 of  menu-complete  steps through the list of possible
	      completions, inserting each match	in turn.  At the  end  of  the
	      list of completions, the bell is rung (subject to	the setting of
	      bell-style) and the original text	is restored.  An argument of n
	      moves n positions	forward	in the list of matches;	a negative ar-
	      gument may be used to move backward through the list.  This com-
	      mand is intended to be bound to TAB, but is unbound by default.
       delete-char-or-list
	      Deletes  the  character under the	cursor if not at the beginning
	      or end of	the line (like delete-char).  If at  the  end  of  the
	      line, behaves identically	to possible-completions.  This command
	      is unbound by default.
       complete-filename (M-/)
	      Attempt filename completion on the text before point.
       possible-filename-completions (C-x /)
	      List the possible	completions of the text	before point, treating
	      it as a filename.
       complete-username (M-~)
	      Attempt  completion  on  the text	before point, treating it as a
	      username.
       possible-username-completions (C-x ~)
	      List the possible	completions of the text	before point, treating
	      it as a username.
       complete-variable (M-$)
	      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 re-
	      moved, the line will be executed by the shell.
       glob-complete-word (M-g)
	      The word before point is treated as a pattern for	 pathname  ex-
	      pansion,	with an	asterisk implicitly appended.  This pattern is
	      used to generate a list of matching file names for possible com-
	      pletions.
       glob-expand-word	(C-x *)
	      The  word	 before	point is treated as a pattern for pathname ex-
	      pansion, and the list of matching	file names  is	inserted,  re-
	      placing  the word.  If a numeric argument	is supplied, an	aster-
	      isk is appended before pathname expansion.
       glob-list-expansions (C-x g)
	      The list	of  expansions	that  would  have  been	 generated  by
	      glob-expand-word	is  displayed,	and the	line is	redrawn.  If a
	      numeric argument is supplied, an	asterisk  is  appended	before
	      pathname expansion.
       dump-functions
	      Print  all  of the functions and their key bindings to the read-
	      line output stream.  If a	numeric	argument is supplied, the out-
	      put  is  formatted  in such a way	that it	can be made part of an
	      inputrc file.
       dump-variables
	      Print all	of the settable	readline variables and their values to
	      the  readline output stream.  If a numeric argument is supplied,
	      the output is formatted in such a	way that it can	be  made  part
	      of an inputrc file.
       dump-macros
	      Print  all of the	readline key sequences bound to	macros and the
	      strings they output.  If a numeric  argument  is	supplied,  the
	      output is	formatted in such a way	that it	can be made part of an
	      inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about	the current instance of	bash.

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

       First,  the command name	is identified.	If 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 op-
       tion are	generated next.	 The words generated by	the pattern  need  not
       match  the  word	being completed.  The GLOBIGNORE shell variable	is not
       used to filter the matches, but the FIGNORE variable is used.

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

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

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

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

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

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

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

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

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

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

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  ma-
       nipulate	 the  history  file.   When using command-line editing,	search
       commands	are available in each editing mode that	provide	access to  the
       history list.

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

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

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

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

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

       Several	shell  options	settable with the shopt	builtin	may be used to
       tailor the behavior of history expansion.  If the histverify shell  op-
       tion  is	 enabled (see the description of the shopt builtin), 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 de-
	      limiter is optional if it	is the last  character	of  the	 event
	      line.   The delimiter may	be quoted in old and new with a	single
	      backslash.  If & appears in new, it is replaced by old.  A  sin-
	      gle  backslash  will  quote the &.  If old is null, it is	set to
	      the last old substituted,	or, if no previous  history  substitu-
	      tions took place,	the last string	in a !?string[?]  search.
       &      Repeat the previous substitution.
       g      Cause changes to be applied over the entire event	line.  This is
	      used in conjunction with `:s' (e.g.,  `:gs/old/new/')  or	 `:&'.
	      If  used with `:s', any delimiter	can be used in place of	/, and
	      the final	delimiter is optional if it is the last	 character  of
	      the event	line.  An a may	be used	as a synonym for g.
       G      Apply  the following `s' modifier	once to	each word in the event
	      line.

SHELL BUILTIN COMMANDS
       Unless otherwise	noted, each builtin command documented in this section
       as accepting options preceded by	- accepts -- to	signify	the end	of the
       options.	 For example, the :, true, false, and test builtins do not ac-
       cept 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 en-
	      vironment	and return the exit status of the  last	 command  exe-
	      cuted from filename.  If filename	does not contain a slash, file
	      names in PATH are	used to	find the  directory  containing	 file-
	      name.   The  file	 searched  for in PATH need not	be executable.
	      When bash	is  not	 in  posix  mode,  the	current	 directory  is
	      searched	if no file is found in PATH.  If the sourcepath	option
	      to the shopt builtin command is turned  off,  the	 PATH  is  not
	      searched.	  If any arguments are supplied, they become the posi-
	      tional parameters	when filename is executed.  Otherwise the  po-
	      sitional	parameters  are	 unchanged.   The return status	is the
	      status of	the last command exited	within the  script  (0	if  no
	      commands	are  executed),	 and false if filename is not found or
	      cannot be	read.

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

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

       bind [-m	keymap]	[-lpsvPSV]
       bind [-m	keymap]	[-q function] [-u function] [-r	keyseq]
       bind [-m	keymap]	-f filename
       bind [-m	keymap]	-x keyseq:shell-command
       bind [-m	keymap]	keyseq:function-name
       bind readline-command
	      Display  current	readline key and function bindings, bind a key
	      sequence to a readline function or  macro,  or  set  a  readline
	      variable.	 Each non-option argument is a command as it would ap-
	      pear in .inputrc,	but each binding or command must be passed  as
	      a	separate argument; e.g., '"\C-x\C-r": re-read-init-file'.  Op-
	      tions, if	supplied, have the following meanings:
	      -m keymap
		     Use keymap	as the keymap to be affected by	the subsequent
		     bindings.	Acceptable keymap names	are emacs, emacs-stan-
		     dard, emacs-meta, emacs-ctlx,  vi,	 vi-move,  vi-command,
		     and  vi-insert.  vi is equivalent to vi-command; emacs is
		     equivalent	to emacs-standard.
	      -l     List the names of all readline functions.
	      -p     Display readline function names and bindings  in  such  a
		     way that they can be re-read.
	      -P     List current readline function names and bindings.
	      -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 en-
		     tered.

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

       break [n]
	      Exit  from  within a for,	while, until, or select	loop.  If n is
	      specified, break n levels.  n must be >= 1.   If	n  is  greater
	      than  the	number of enclosing loops, all enclosing loops are ex-
	      ited.  The return	value is 0 unless the shell is not executing a
	      loop when	break is executed.

       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 op-
	      tion says	to use the physical  directory	structure  instead  of
	      following	 symbolic  links  (see	also  the -P option to the set
	      builtin command);	the -L option forces symbolic links to be fol-
	      lowed.   An  argument  of	- is equivalent	to $OLDPWD.  If	a non-
	      empty directory name from	CDPATH is used,	or if -	is  the	 first
	      argument,	 and  the directory change is successful, the absolute
	      pathname of the new working directory is written to the standard
	      output.	The return value is true if the	directory was success-
	      fully changed; false otherwise.

       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  op-
	      tion  is	supplied, a description	of command is printed.	The -v
	      option causes a single word indicating the command or file  name
	      used to invoke command to	be displayed; the -V option produces a
	      more verbose description.	 If the	-V or -v option	 is  supplied,
	      the  exit	 status	 is  0 if command was found, and 1 if not.  If
	      neither option is	supplied and an	error occurred or command can-
	      not  be found, the exit status is	127.  Otherwise, the exit sta-
	      tus of the command builtin is the	exit status of command.

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

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

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

       complete	 [-abcdefgjksuv] [-o comp-option] [-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  Program-
	      mable Completion.

	      Other  options,  if specified, have the following	meanings.  The
	      arguments	to the -G, -W, and -X options (and, if necessary,  the
	      -P  and -S options) should be quoted to protect them from	expan-
	      sion before the complete builtin is invoked.
	      -o comp-option
		      The comp-option controls several aspects	of  the	 comp-
		      spec's  behavior beyond the simple generation of comple-
		      tions.  comp-option may be one of:
		      bashdefault
			      Perform the rest of the default bash completions
			      if the compspec generates	no matches.
		      default Use  readline's  default	filename completion if
			      the compspec generates no	matches.
		      dirnames
			      Perform directory	name completion	if  the	 comp-
			      spec generates no	matches.
		      filenames
			      Tell  readline that the compspec generates file-
			      names, so	it can perform	any  filename-specific
			      processing  (like	 adding	 a  slash to directory
			      names or suppressing trailing spaces).  Intended
			      to be used with shell functions.
		      nospace Tell  readline  not  to  append a	space (the de-
			      fault) to	words completed	 at  the  end  of  the
			      line.
		      plusdirs
			      After  any  matches  defined by the compspec are
			      generated,  directory  name  completion  is  at-
			      tempted and any matches are added	to the results
			      of the other actions.
	      -A action
		      The action may be	one of the  following  to  generate  a
		      list of possible completions:
		      alias   Alias names.  May	also be	specified as -a.
		      arrayvar
			      Array variable names.
		      binding Readline key binding names.
		      builtin Names  of	 shell	builtin	commands.  May also be
			      specified	as -b.
		      command Command names.  May also be specified as -c.
		      directory
			      Directory	names.	May also be specified as -d.
		      disabled
			      Names of disabled	shell builtins.
		      enabled Names of enabled shell builtins.
		      export  Names of exported	shell variables.  May also  be
			      specified	as -e.
		      file    File names.  May also be specified as -f.
		      function
			      Names of shell functions.
		      group   Group names.  May	also be	specified as -g.
		      helptopic
			      Help topics as accepted by the help builtin.
		      hostname
			      Hostnames,  as  taken from the file specified by
			      the HOSTFILE shell variable.
		      job     Job names, if job	control	is active.   May  also
			      be specified as -j.
		      keyword Shell  reserved words.  May also be specified as
			      -k.
		      running Names of running jobs, if	job control is active.
		      service Service names.  May also be specified as -s.
		      setopt  Valid arguments for the -o  option  to  the  set
			      builtin.
		      shopt   Shell  option  names  as	accepted  by the shopt
			      builtin.
		      signal  Signal names.
		      stopped Names of stopped jobs, if	job control is active.
		      user    User names.  May also be specified as -u.
		      variable
			      Names of all shell variables.  May also be spec-
			      ified as -v.
	      -G globpat
		      The  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 en-
	      closing loops, the last enclosing	loop (the ``top-level''	 loop)
	      is  resumed.  The	return value is	0 unless the shell is not exe-
	      cuting a loop when continue is executed.

       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 im-
	      plies -f.	 The following options can be used to restrict	output
	      to  variables  with the specified	attribute or to	give variables
	      attributes:
	      -a     Each name is an 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 in-
		     herit 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 en-
		     vironment.

	      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 as-
	      sign a value to an array variable	without	using the compound as-
	      signment	syntax	(see  Arrays above), one of the	names is not a
	      valid shell variable name, an attempt is made to turn off	 read-
	      only  status for a readonly variable, an attempt is made to turn
	      off array	status for an array variable, or an attempt is made to
	      display a	non-existent function with -f.

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

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

       disown [-ar] [-h] [jobspec ...]
	      Without  options,	 each jobspec is removed from the table	of ac-
	      tive jobs.  If the -h option is given, each jobspec is  not  re-
	      moved  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 in-
	      terprets 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  en-
	      abled.   For  example, to	use the	test binary found via the PATH
	      instead of the shell builtin version, run	 ``enable  -n  test''.
	      The  -f  option  means to	load the new builtin command name from
	      shared object filename, on systems that support dynamic loading.
	      The  -d  option will delete a builtin previously loaded with -f.
	      If no name arguments are given, or if the	-p option is supplied,
	      a	list of	shell builtins is printed.  With no other option argu-
	      ments, the list consists of all enabled shell builtins.	If  -n
	      is  supplied, only disabled builtins are printed.	 If -a is sup-
	      plied, the list printed includes all builtins, with  an  indica-
	      tion  of whether or not each is enabled.	If -s is supplied, the
	      output is	restricted to the POSIX	special	builtins.  The	return
	      value  is	 0 unless a name is not	a shell	builtin	or there is an
	      error loading a new builtin from a shared	object.

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

       exec [-cl] [-a name] [command [arguments]]
	      If  command is specified,	it replaces the	shell.	No new process
	      is created.  The arguments become	the arguments to command.   If
	      the -l option is supplied, the shell places a dash at the	begin-
	      ning of the zeroth 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  ex-
	      ported  in  this shell is	printed.  The -n option	causes the ex-
	      port property to be removed from each name.  If a	variable  name
	      is  followed by =word, the value of the variable is set to word.
	      export returns an	exit status of 0 unless	an invalid  option  is
	      encountered,  one	 of  the  names	 is not	a valid	shell variable
	      name, or -f is supplied with a name that is not a	function.

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

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

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

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

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

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

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

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

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

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

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

       help [-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 un-
	      less no command matches pattern.

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

	      If the HISTTIMEFORMAT 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 ex-
	      ecutes command passing it	args, returning	its exit status.

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

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

	      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 di-
		     rectories to the stack, so	that only the stack is manipu-
		     lated.
	      dir    Adds dir to the directory stack at	the top, making	it the
		     new current working directory.

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

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

       read [-ers] [-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  de-
	      scriptor	fd  supplied  as an argument to	the -u option, and the
	      first word is assigned to	the first name,	the second word	to the
	      second  name, and	so on, with leftover words and their interven-
	      ing separators assigned to the last name.	 If  there  are	 fewer
	      words read from the input	stream than names, the remaining names
	      are assigned empty values.  The characters in IFS	 are  used  to
	      split  the  line into words.  The	backslash character (\)	may be
	      used to remove any special meaning for the next  character  read
	      and  for line continuation.  Options, if supplied, have the fol-
	      lowing meanings:
	      -a aname
		     The words are assigned to sequential indices of the array
		     variable aname, starting at 0.  aname is unset before any
		     new values	are assigned.  Other name  arguments  are  ig-
		     nored.
	      -d delim
		     The first character of delim is used to terminate the in-
		     put line, rather than newline.
	      -e     If	the standard input is coming from a terminal, readline
		     (see READLINE above) is used to obtain the	line.
	      -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  en-
	      countered, read times out, or an invalid file descriptor is sup-
	      plied 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  op-
	      tions  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 or-
	      der, 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 ig-
		      nored by interactive shells.
	      -o option-name
		      The option-name can be one of the	following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use an emacs-style command line  editing	inter-
			      face.  This is enabled by	default	when the shell
			      is interactive, unless the shell is started with
			      the --noediting option.
		      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 ``IG-
			      NOREEOF=10'' had been executed (see Shell	 Vari-
			      ables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.  nolog Currently ignored.
		      notify  Same as -b.
		      nounset Same as -u.
		      onecmd  Same as -t.
		      physical
			      Same as -P.
		      pipefail
			      If  set,	the  return value of a pipeline	is the
			      value of the last	(rightmost)  command  to  exit
			      with  a non-zero status, or zero if all commands
			      in the pipeline exit successfully.  This	option
			      is disabled by default.
		      posix   Change  the  behavior  of	bash where the default
			      operation	differs	from  the  POSIX  standard  to
			      match the	standard (posix	mode).
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      vi      Use a vi-style command line editing interface.
		      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 op-
		      tion  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 ex-
		      ecuted  in a subshell environment.  The DEBUG and	RETURN
		      traps are	normally not inherited in such cases.
	      --      If no arguments follow this option, then the  positional
		      parameters are unset.  Otherwise,	the positional parame-
		      ters are set to the args,	even if	 some  of  them	 begin
		      with a -.
	      -	      Signal  the  end of options, cause all remaining args to
		      be assigned to the positional parameters.	 The -x	and -v
		      options are turned off.  If there	are no args, the posi-
		      tional parameters	remain unchanged.

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

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

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

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

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

	      The list of shopt	options	is:

	      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.
	      colonbreakswords
		      If set, and readline is being used, bash will treat : as
		      separating  word	being  completed (see Completing under
		      READLINE above).	This is	enabled	by default.
	      dotglob If set, bash includes filenames beginning	with a `.'  in
		      the results of pathname expansion.
	      execfail
		      If set, a	non-interactive	shell will not exit if it can-
		      not execute the file specified as	 an  argument  to  the
		      exec  builtin  command.	An  interactive	shell does not
		      exit if exec fails.
	      expand_aliases
		      If set, aliases are expanded as  described  above	 under
		      ALIASES.	This option is enabled by default for interac-
		      tive shells.
	      extdebug
		      If set, behavior intended	for use	by  debuggers  is  en-
		      abled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name	supplied as an argument.
		      2.     If	 the  command  run by the DEBUG	trap returns a
			     non-zero value, the next command is  skipped  and
			     not executed.
		      3.     If	 the  command  run by the DEBUG	trap returns a
			     value of 2, and the shell is executing in a  sub-
			     routine  (a shell function	or a shell script exe-
			     cuted by the . or source builtins), a call	to re-
			     turn is simulated.
		      4.     BASH_ARGC	and BASH_ARGV are updated as described
			     in	their descriptions above.
		      5.     Function tracing is enabled:   command  substitu-
			     tion, shell functions, and	subshells invoked with
			     ( command ) inherit the DEBUG and RETURN traps.
		      6.     Error tracing is enabled:	command	 substitution,
			     shell  functions,	and  subshells	invoked	with (
			     command ) inherit the ERROR trap.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      extquote
		      If  set,	$'string'  and	$"string" quoting is performed
		      within  ${parameter}  expansions	enclosed   in	double
		      quotes.  This option is enabled by default.
	      failglob
		      If  set,	patterns  which	fail to	match filenames	during
		      pathname expansion result	in an expansion	error.
	      force_fignore
		      If set, the suffixes  specified  by  the	FIGNORE	 shell
		      variable	cause words to be ignored when performing word
		      completion even if the ignored words are the only	possi-
		      ble  completions.	  See  SHELL VARIABLES above for a de-
		      scription	of FIGNORE.  This option  is  enabled  by  de-
		      fault.
	      gnu_errfmt
		      If set, shell error messages are written in the standard
		      GNU error	message	format.
	      histappend
		      If set, the history list is appended to the  file	 named
		      by the value of the HISTFILE variable when the shell ex-
		      its, rather than overwriting the file.
	      histreedit
		      If set, and readline is being used, a user is given  the
		      opportunity to re-edit a failed history substitution.
	      histverify
		      If  set, and readline is being used, the results of his-
		      tory substitution	are  not  immediately  passed  to  the
		      shell  parser.   Instead,	 the  resulting	line is	loaded
		      into the readline	editing	buffer,	allowing further modi-
		      fication.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to
		      perform hostname completion when a word containing  a  @
		      is   being  completed  (see  Completing  under  READLINE
		      above).  This is enabled by default.
	      huponexit
		      If set, bash will	send SIGHUP to all jobs	when an	inter-
		      active login shell exits.
	      implicitcd
		      If  this	is set,	a directory name typed as a command is
		      treated as a request to change to	that directory.	  This
		      behavior	is  inhibited  in  non-interactive mode	or for
		      command strings with more	than one word.	 Changing  di-
		      rectory  takes  precedence  over	executing a like-named
		      command, but  it	is  done  after	 alias	substitutions.
		      Tilde and	variable expansions work as expected.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word
		      and all remaining	characters on that line	to be  ignored
		      in  an interactive shell (see COMMENTS above).  This op-
		      tion is enabled by default.
	      lithist If set, and the cmdhist option  is  enabled,  multi-line
		      commands are saved to the	history	with embedded newlines
		      rather than using	semicolon separators where possible.
	      login_shell
		      The shell	sets this option if it is started as  a	 login
		      shell  (see  INVOCATION  above).	 The  value may	not be
		      changed.
	      mailwarn
		      If set, and a file that bash is checking	for  mail  has
		      been  accessed  since  the last time it was checked, the
		      message ``The mail in mailfile has been read''  is  dis-
		      played.
	      no_empty_cmd_completion
		      If  set,	and  readline is being used, bash will not at-
		      tempt to search the PATH for possible  completions  when
		      completion is attempted on an empty line.
	      nocaseglob
		      If  set,	bash  matches  filenames in a case-insensitive
		      fashion when performing pathname expansion (see Pathname
		      Expansion	above).
	      nocasematch
		      If  set,	bash  matches  patterns	 in a case-insensitive
		      fashion when performing matching while executing case or
		      [[ conditional commands.
	      nullglob
		      If  set,	bash allows patterns which match no files (see
		      Pathname Expansion above)	to expand to  a	 null  string,
		      rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Pro-
		      grammable	Completion above) are enabled.	This option is
		      enabled by default.
	      promptvars
		      If set, prompt strings undergo parameter expansion, com-
		      mand substitution, arithmetic expansion, and  quote  re-
		      moval  after  being  expanded  as	described in PROMPTING
		      above.  This option is enabled by	default.
	      restricted_shell
		      The shell	sets this option  if  it  is  started  in  re-
		      stricted	mode  (see RESTRICTED SHELL below).  The value
		      may not be changed.  This	is not reset when the  startup
		      files  are  executed, allowing the startup files to dis-
		      cover whether or not a shell is restricted.
	      shift_verbose
		      If set, the shift	builtin	prints an error	 message  when
		      the shift	count exceeds the number of positional parame-
		      ters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to
		      find  the	 directory  containing the file	supplied as an
		      argument.	 This option is	enabled	by default.
	      xpg_echo
		      If set, the echo builtin	expands	 backslash-escape  se-
		      quences by default.
       suspend [-f]
	      Suspend  the execution of	this shell until it receives a SIGCONT
	      signal.  The -f option says not to complain if this is  a	 login
	      shell;  just  suspend anyway.  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  re-
	      ceives signal(s) sigspec.	 If arg	is absent (and there is	a sin-
	      gle sigspec) or -, each specified	signal is reset	to its	origi-
	      nal  disposition	(the value it had upon entrance	to the shell).
	      If arg is	the null string	the signal specified by	 each  sigspec
	      is  ignored by the shell and by the commands it invokes.	If arg
	      is not present and -p has	been supplied, then the	trap  commands
	      associated with each sigspec are displayed.  If no arguments are
	      supplied or if only -p is	given, trap prints the	list  of  com-
	      mands  associated	 with  each  signal.  The -l option causes the
	      shell to print a list of signal names  and  their	 corresponding
	      numbers.	 Each sigspec is either	a signal name defined in <sig-
	      nal.h>, or a signal number.  Signal names	are  case  insensitive
	      and  the	SIG  prefix is optional.  If a sigspec is EXIT (0) the
	      command arg is executed on exit from the shell.  If a sigspec is
	      DEBUG,  the command arg is executed before every simple command,
	      for command, case	command, select	command, every arithmetic  for
	      command,	and before the first command executes in a shell func-
	      tion (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 exe-
	      cuted whenever a simple command has a non-zero exit status, sub-
	      ject 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 com-
	      mand arg is executed each	time a shell function or a script exe-
	      cuted with the . or source builtins finishes 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  re-
	      turn  status  is false if	any sigspec is invalid;	otherwise trap
	      returns true.

       type [-aftpP] name [name	...]
	      With no options, indicate	how each name would be interpreted  if
	      used as a	command	name.  If the -t option	is used, type prints a
	      string which is one of alias,  keyword,  function,  builtin,  or
	      file  if	name  is  an  alias,  shell  reserved  word, function,
	      builtin, or disk file, respectively.  If the name	is not	found,
	      then  nothing  is	 printed,  and	an exit	status of false	is re-
	      turned.  If the -p option	is used, type either returns the  name
	      of  the  disk file that would be executed	if name	were specified
	      as a command name, or nothing if ``type -t name''	would not  re-
	      turn  file.   The	 -P option forces a PATH search	for each name,
	      even if ``type -t	name'' would not return	file.  If a command is
	      hashed,  -p  and	-P print the hashed value, not necessarily the
	      file that	appears	first in PATH.	If the -a option is used, type
	      prints  all of the places	that contain an	executable named name.
	      This includes aliases and	functions, if and only if the  -p  op-
	      tion is not also used.  The table	of hashed commands is not con-
	      sulted when using	-a.  The -f option suppresses  shell  function
	      lookup,  as  with	the command builtin.  type returns true	if 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 re-
	      source  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
	      -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 un-
	      set.  If -f is specified,	each name refers to a shell  function,
	      and  the function	definition is removed.	Each unset variable or
	      function is removed from the environment	passed	to  subsequent
	      commands.	 If any	of RANDOM, SECONDS, LINENO, HISTCMD, FUNCNAME,
	      GROUPS, or DIRSTACK are unset, they lose their  special  proper-
	      ties,  even  if they are subsequently reset.  The	exit status is
	      true unless a name is readonly.

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

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

       o      changing directories with	cd

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

       o      specifying command names containing /

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

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

       o      importing	 function  definitions	from  the shell	environment at
	      startup

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

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

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

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

       o      Using the	 enable	 builtin  command  to  enable  disabled	 shell
	      builtins

       o      specifying the -p	option to the command builtin command

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

       These restrictions are enforced after any startup files are read.

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

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

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

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

       Chet Ramey, Case	Western	Reserve	University
       chet@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.

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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