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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) 1989-2002 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 IEEE POSIX
       Shell and Tools specification (IEEE Working Group 1003.2).

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 ouput.	 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.

       --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	1003.2	standard  to match the standard	(posix
	      mode).

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

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

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

ARGUMENTS
       If arguments remain after option	processing, and	neither	the -c nor the
       -s option has been supplied, the	first argument is assumed  to  be  the
       name  of	 a file	containing shell commands.  If bash is invoked in this
       fashion,	$0 is set to the name of the file, and the positional  parame-
       ters  are set to	the remaining arguments.  Bash reads and executes com-
       mands from this file, then exits.  Bash's exit status is	the exit  sta-
       tus of the last command executed	in the script.	If no commands are 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  output  are  both  con-
       nected  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).

       If  the	reserved  word !  precedes a pipeline, the exit	status of that
       pipeline	is the logical NOT of the exit status  of  the	last  command.
       Otherwise,  the	status	of the pipeline	is the exit status of the last
       command.	 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.   Variable  assignments  and
	      builtin  commands	that affect the	shell's	environment do not re-
	      main in effect after the command completes.  The	return	status
	      is the exit status of list.

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

       ((expression))
	      The expression is	evaluated according to the rules described 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.

	      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.   The	return
	      value  is	0 if the string	matches	or does	not match the pattern,
	      respectively, and	1 otherwise.  Any part of the pattern  may  be
	      quoted to	force it to be matched as a string.

	      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).  When a match is
	      found, the corresponding list  is	 executed.   After  the	 first
	      match,  no subsequent matches are	attempted.  The	exit status is
	      zero if no pattern matches.  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.

       [ function ] name () { list; }
	      This defines a function named name.  The body of the function is
	      the list of commands between { and }.   This  list  is  executed
	      whenever name is specified as the	name of	a simple command.  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, the his-
       tory 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 \.
       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 back-
       slash.

       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 specifed  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.  For the shell's purposes, a variable is a parameter denoted  by
       a  name.	  A  variable  has  a  value and zero or more attributes.  At-
       tributes	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  subject  to	arithmetic expansion even if the $((...)) expansion is
       not used	(see Arithmetic	Expansion below).  Word	splitting is not  per-
       formed, with the	exception of "$@" as explained below under Special Pa-
       rameters.  Pathname expansion is	not performed.	Assignment  statements
       may also	appear as arguments to the declare, typeset, export, readonly,
       and local builtin commands.

   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"
	      "$2"  ...	  When there are no positional parameters, "$@"	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 file name of the shell  or
	      shell  script  being  executed  as  passed in the	argument list.
	      Subsequently, expands to the last	argument to the	previous  com-
	      mand,  after  expansion.	Also set to the	full file name of each
	      command executed and placed in the environment exported to  that
	      command.	 When  checking	mail, this parameter holds the name of
	      the mail file currently being checked.

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands to the full file name used to invoke  this  instance  of
	      bash.
       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_WORDS
	      An array variable	(see Arrays below) consisting of the  individ-
	      ual  words in the	current	command	line.  This variable is	avail-
	      able only	in shell functions invoked by the programmable comple-
	      tion facilities (see Programmable	Completion below).

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

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

       FUNCNAME
	      The name of any currently-executing shell	function.  This	 vari-
	      able  exists  only  when a shell function	is executing.  Assign-
	      ments 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).
       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
	      If set to	a value	of ignorespace,	lines which begin with a space
	      character	are not	entered	on the history	list.	If  set	 to  a
	      value  of	 ignoredups,  lines matching the last history line are
	      not entered.  A value of ignoreboth combines  the	 two  options.
	      If  unset,  or  if  set to any other value than those above, all
	      lines read by the	parser are saved on the	history	list,  subject
	      to  the value of HISTIGNORE.  This variable's function is	super-
	      seded by 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,  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.
       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).	 The default path is system-dependent, and  is
	      set  by  the administrator who installs bash.  A common value is
	      ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.''.
       POSIXLY_CORRECT
	      If this variable is in the environment  when  bash  starts,  the
	      shell  enters posix mode before reading the startup files, as if
	      the --posix invocation option had	been supplied.	If it  is  set
	      while  the  shell	is running, bash enables posix mode, as	if the
	      command set -o posix had been executed.
       PROMPT_COMMAND
	      If set, the value	is executed as a command prior to issuing each
	      primary prompt.
       PS1    The  value  of  this parameter is	expanded (see PROMPTING	below)
	      and used as the primary prompt string.   The  default  value  is
	      ``\s-\v\$	''.
       PS2    The  value of this parameter is expanded as with PS1 and used as
	      the secondary prompt string.  The	default	is ``> ''.
       PS3    The value	of this	parameter is used as the prompt	for the	select
	      command (see SHELL GRAMMAR above).
       PS4    The  value  of  this  parameter  is expanded as with PS1 and the
	      value is printed before each command bash	displays during	an 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 ``+	''.
       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.

       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
	      %	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.	 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	expan-
       sion  is	 the  number  of  elements in the array.  Referencing an array
       variable	without	a subscript is equivalent to referencing element zero.

       The unset builtin is used to destroy arrays.  unset name[subscript] de-
       stroys the array	element	at index subscript.  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 a series of comma-separated
       strings between a pair of braces, followed 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'.

       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.  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 expansion, the	string ${ is not  con-
       sidered 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 =.  In these cases, tilde	expansion is also per-
       formed.	Consequently, one may use file names with  tildes  in  assign-
       ments 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  paramter	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 exception to this is the expansion of
       ${!prefix*} described below.

       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]}.  Substring indexing is	zero-based un-
	      less the positional parameters are used, in which	case  the  in-
	      dexing starts at 1.

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

       ${#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}
       ${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.	In  the	 first
	      form,  only the first match is replaced.	The second form	causes
	      all matches of pattern to	be replaced with string.   If  pattern
	      begins  with  #,	it must	match at the beginning of the expanded
	      value of parameter.  If pattern begins with %, it	must match  at
	      the  end of the expanded value of	parameter.  If string is null,
	      matches of pattern are deleted and the / following  pattern  may
	      be  omitted.  If parameter is @ or *, the	substitution operation
	      is applied to each positional parameter in turn, and the	expan-
	      sion  is	the resultant list.  If	parameter is an	array variable
	      subscripted with @ or *, the substitution	operation  is  applied
	      to  each	member	of the array in	turn, and the expansion	is the
	      resultant	list.

   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 substitutions  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 shell	option nocase-
       glob is enabled,	the match is performed without regard to the  case  of
       alphabetic  characters.	When a pattern is used for pathname expansion,
       the character ``.''  at the start of a name or immediately following  a
       slash  must  be	matched	explicitly, unless the shell option dotglob is
       set.  When matching a pathname, the  slash  character  must  always  be
       matched	explicitly.   In  other	 cases,	 the  ``.''   character	is not
       treated specially.  See the description	of  shopt  below  under	 SHELL
       BUILTIN	COMMANDS  for  a  description of the nocaseglob, nullglob, 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,	even when GLOBIGNORE is	set.  However, setting GLOBIGNORE  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.  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.2 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 exactly 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.

   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
       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 alias name and the
       replacement text	may contain  any  valid	 shell	input,	including  the
       metacharacters listed above, with the exception that the	alias name may
       not contain =.  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	expan-
       sion.

       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.  Positional parameter  0	is  unchanged.
       The  FUNCNAME  variable	is  set	 to the	name of	the function while the
       function	is executing.  All other aspects of the	shell execution	 envi-
       ronment are identical between a function	and its	caller with the	excep-
       tion that the DEBUG trap	(see the description of	the trap builtin under
       SHELL  BUILTIN COMMANDS below) is not inherited unless the function has
       been given the trace attribute (see  the	 description  of  the  declare
       builtin below).

       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.  When	a function completes, the values of the	positional pa-
       rameters	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.  Functions may	be exported so
       that subshells automatically have them defined with the	-f  option  to
       the export builtin.

       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 builtin command and	Arithmetic Expansion).
       Evaluation is done in fixed-width integers with no check	for  overflow,
       though division by 0 is trapped and flagged as an error.	 The operators
       and their precedence and	associativity are the same as in  the  C  lan-
       guage.	The  following	list  of  operators  is	grouped	into levels of
       equal-precedence	operators.  The	levels are listed in order of decreas-
       ing 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 evaluation
       = *= /= %= += -=	<<= >>=	&= ^= |=
	      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.  The value of a variable is evaluated	as  an	arith-
       metic expression	when it	is referenced.	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	interchangably 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.

       -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.
       -n string
       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 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 the inherited
	      from the shell's parent, and traps ignored by the	shell are  ig-
	      nored

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

       Command substitution and	asynchronous commands are invoked  in  a  sub-
       shell  environment that is a duplicate of the shell environment,	except
       that traps caught by the	shell are reset	to the values that  the	 shell
       inherited from its parent at invocation.	 Builtin commands that are in-
       voked as	part of	a pipeline are also executed in	 a  subshell  environ-
       ment.   Changes	made  to  the  subshell	 environment 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.

       Synchronous jobs	started	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  as  well.	  Com-
       mands  run as a result of command substitution ignore the keyboard-gen-
       erated job control signals SIGTTIN, SIGTTOU, 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.

       When bash receives a signal for which a trap has	been set while waiting
       for a command to	complete, 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 -.

       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 + patchelvel (e.g., 2.00.0)
	      \w     the current working directory
	      \W     the basename of the current working directory
	      \!     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.
       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.
       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
	      If  set  to  on, the history code	attempts to place point	at the
	      same location on each history line retrived  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.
       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.
       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.
       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.
       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 ouput.  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.
       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,  arithmetic  expansion,  and
       pathname	 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 com-
       pleted, 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.

       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 default option was supplied
       to complete when	the compspec was defined, readline's  default  comple-
       tion will be performed if the compspec generates	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	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, = or (.
       !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.

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.
       : [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 the suspended job jobspec in the background, as if	it had
	      been started with	&.  If jobspec is not present, the shell's no-
	      tion  of	the  current job is used.  bg jobspec returns 0	unless
	      run when job control is disabled or, when	run with  job  control
	      enabled,	if  jobspec  was not found or started without job con-
	      trol.

       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.   The	return
	      value  is	 true if the directory was successfully	changed; false
	      otherwise.

       command [-pVv] command [arg ...]
	      Run command with args  suppressing  the  normal  shell  function
	      lookup.  Only builtin commands or	commands found in the PATH are
	      executed.	 If the	-p option is given, the	search for command  is
	      performed	 using	a default value	for PATH that is guaranteed to
	      find all of the standard utilities.  If either the -V or -v  op-
	      tion  is	supplied, a description	of command is printed.	The -v
	      option causes a single word indicating the command or 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:
		      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.
	      -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.	The -F option implies -f.  The follow-
	      ing 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 trap 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.  The return value is 0	unless an invalid  op-
	      tion is encountered, an attempt is made to define	a function us-
	      ing ``-f foo=bar'', an attempt is	made to	assign a  value	 to  a
	      readonly	variable,  an  attempt is made to assign a value to an
	      array variable without using the compound	assignment syntax (see
	      Arrays  above),  one  of the names is not	a valid	shell variable
	      name, an attempt is made to turn off readonly status for a read-
	      only  variable,  an attempt is made to turn off array status for
	      an array variable, or an attempt is made to display a  non-exis-
	      tent function with -f.

       dirs [-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)
	      \nnn   the  eight-bit  character	whose value is the octal value
		     nnn (one to three octal digits)
	      \xHH   the eight-bit character whose value  is  the  hexadecimal
		     value HH (one or two hex digits)

       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 the named variables.	export
	      returns an exit status of	0 unless an invalid option is  encoun-
	      tered,  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 filename is supplied,	it  is
	      used as the name of the history file; if not, the	value of HIST-
	      FILE is used.  Options, if supplied, have	 the  following	 mean-
	      ings:
	      -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.

	      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 signal  name  such
	      as  SIGKILL  or  a signal	number;	signum is a signal number.  If
	      sigspec is a signal name,	the name may be	given with or  without
	      the  SIG prefix.	If sigspec is not present, then	SIGTERM	is as-
	      sumed.  An argument of -l	lists the signal names.	 If any	 argu-
	      ments  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 ei-
	      ther a signal number or the exit status of a process  terminated
	      by  a signal.  kill returns true if at least one signal was suc-
	      cessfully	sent, or false if an error occurs or an	invalid	option
	      is encountered.

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

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

       logout Exit a login shell.

       popd [-n] [+n] [-n]
	      Removes  entries	from  the directory stack.  With no arguments,
	      removes the top directory	from the stack,	and performs a	cd  to
	      the new top directory.  Arguments, if supplied, have the follow-
	      ing meanings:
	      +n     Removes the nth entry counting from the left of the  list
		     shown  by	dirs, starting with zero.  For example:	``popd
		     +0'' removes the first directory, ``popd +1'' the second.
	      -n     Removes the nth entry counting from the right of the list
		     shown  by	dirs, starting with zero.  For example:	``popd
		     -0'' removes the last directory, ``popd -1'' the next  to
		     last.
	      -n     Suppresses	 the  normal change of directory when removing
		     directories from the stack, so that only the stack	is 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 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, and	%q causes printf to output the
	      corresponding argument in	a format that can be reused  as	 shell
	      input.

	      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 ...]
	      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.
	      The  return status is 0 unless an	invalid	option is encountered,
	      one of the names is not a	valid shell variable name,  or	-f  is
	      supplied with a name that	is not a function.

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

       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.   The	output
	      is  sorted  according  to	 the current locale.  When options are
	      specified, they set or unset shell  attributes.	Any  arguments
	      remaining	 after the options are processed are treated as	values
	      for the positional parameters and	are assigned, in order,	to $1,
	      $2,  ...	 $n.   Options,	if specified, have the following mean-
	      ings:
	      -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	 an  until  or
		      while  loop, part	of 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.
		      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.
		      posix   Change  the  behavior  of	bash where the default
			      operation	differs	from the POSIX 1003.2 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, display the ex-
		      panded value of PS4, followed by the command and its ex-
		      panded arguments.
	      -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 >.
	      -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.
	      --      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.
	      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.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      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.
	      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).
	      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	variable and parameter
		      expansion	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.

	      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 or -,	all  specified
	      signals  are reset to their original values (the values they had
	      upon entrance to the shell).  If arg is the null string the sig-
	      nal specified by each sigspec is ignored by the shell and	by the
	      commands it invokes.  If arg is not present and -p has been sup-
	      plied,  then  the	trap commands associated with each sigspec are
	      displayed.  If no	arguments are supplied or if only -p is	given,
	      trap  prints  the	 list  of commands associated with each	signal
	      number.  Each sigspec is either a	signal name defined  in	 <sig-
	      nal.h>,  or  a signal number.  If	a sigspec is EXIT (0) the com-
	      mand arg is executed on exit from	the shell.  If	a  sigspec  is
	      DEBUG,  the  command  arg	is executed after every	simple command
	      (see SHELL GRAMMAR above).  If a sigspec is ERR, the command arg
	      is  executed  whenever a simple command has a non-zero exit sta-
	      tus.  The	ERR trap is not	executed if the	failed command is part
	      of an until or while loop, part of an if statement, part of a &&
	      or || list, or if	the command's return value is  being  inverted
	      via !.  The -l option causes the shell to	print a	list of	signal
	      names and	their corresponding numbers.  Signals ignored upon en-
	      try  to  the  shell cannot be trapped or reset.  Trapped signals
	      are reset	to their original values in a child process when it is
	      created.	 The return status is false if any sigspec is invalid;
	      otherwise	trap returns true.

       type [-aftpP] name [name	...]
	      With no options, indicate	how each name would be interpreted  if
	      used as a	command	name.  If the -t option	is used, type prints a
	      string which is one of alias,  keyword,  function,  builtin,  or
	      file  if	name  is  an  alias,  shell  reserved  word, function,
	      builtin, or disk file, respectively.  If the name	is not	found,
	      then  nothing  is	 printed,  and	an exit	status of false	is 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 [-SHacdflmnpstuv [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
	      -f     The maximum size of files created by the shell
	      -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)
	      -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

	      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 specifed, 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 does not exist	or is readonly.

       wait [n]
	      Wait  for	 the specified process and return its termination sta-
	      tus.  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  processes
	      are waited for, and the return status is zero.  If n specifies a
	      non-existent process or job, the return status is	 127.	Other-
	      wise,  the  return status	is the exit status of the last process
	      or job waited for.

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

       o      changing directories with	cd

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

       o      specifying command names containing /

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

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

       o      importing	function definitions from  the	shell  environment  at
	      startup

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

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

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

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

       o      Using  the  enable  builtin  command  to	enable	disabled shell
	      builtins

       o      specifying the -p	option to the command builtin command

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

       These restrictions are enforced after any startup files are read.

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

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

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

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

       Chet Ramey, Case	Western	Reserve	University
       chet@ins.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 that you	have.

       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@ins.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.

       Array variables may not (yet) be	exported.

GNU Bash-2.05b			 2002 July 15			       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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