BASH(1)							  BASH(1)



NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2001 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 incorporates 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 description of  the	set  builtin
       command, bash interprets the following options when it is invoked:

       -c string If  the  -c  option is present, then commands are read from string.  If there are arguments
		 after the string, they are assigned to the positional parameters, starting with $0.
       -r	 If the -r option is present, the shell becomes restricted (see RESTRICTED SHELL below).
       -i	 If the -i option is present, the shell is interactive.
       -s	 If the -s option is present, or if no arguments remain after option processing,  then	com�
		 mands 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 subject to language translation when the current locale is not C
		 or POSIX.  This implies the -n option; no commands will be executed.
       --	 A -- signals the end of options and disables  further	option	processing.   Any  arguments
		 after the -- are treated as filenames and arguments.  An argument of - is equivalent to --.

       Bash also interprets a number of multi-character options.  These options must appear on	the  command
       line before the single-character options in order for them to be recognized.

       --dump-po-strings
	      Equivalent to -D, but the output is in the GNU gettext po (portable object) file format.
       --dump-strings
	      Equivalent to -D.
       --help Display a usage message on standard output and exit successfully.
       --init-file file
       --rcfile file
	      Execute  commands	 from file instead of the standard personal initialization file ~/.bashrc if
	      the shell is interactive (see INVOCATION below).

       --login
	      Make bash act as if it had been invoked as a login shell (see INVOCATION below).

       --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  initial�
	      ization  files  ~/.bash_profile,	~/.bash_login,	or ~/.profile.	By default, bash reads these
	      files when it is invoked as a login shell (see INVOCATION below).

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

       --posix
	      Change the behavior of bash where the default operation differs from the POSIX 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 limitations 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 standard output and exit success�
	      fully.

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  parameters  are	set  to	 the
       remaining  arguments.  Bash reads and executes commands from this file, then exits.  Bash's exit sta�
       tus is the exit status of the last command executed in the script.  If no commands are executed,	 the
       exit status is 0.

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	connected  to terminals (as determined by isatty(3)), or one
       started with the -i option.  PS1 is set and $- includes i if bash is interactive,  allowing  a  shell
       script or a startup file to test this state.

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

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

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

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

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

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

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

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

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

DEFINITIONS
       The following definitions are used throughout the rest of this document.
       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  underscores,  and	 beginning  with  an
	      alphabetic character or an underscore.  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 following symbols:
	      || & && ; ;; ( ) | <newline>

RESERVED WORDS
       Reserved	 words	are  words that have a special meaning to the shell.  The following words are recog�
       nized 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 followed by blank-separated words and
       redirections, and terminated by a control operator.  The first word specifies the command to be	exe�
       cuted.  The remaining words are passed as arguments to the invoked command.

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

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

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

       The  standard  output  of command is connected to the standard input of command2.  This connection is
       performed before any redirections 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.

       If  a  command  is  terminated by the control operator &, the shell executes the command in the back�
       ground 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, respectively.  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 remain in effect after the command completes.	The return status is
	      the exit status of list.

       { list; }
	      list is simply executed in the current shell environment.	 list must be terminated with a new�
	      line or semicolon.  This is known as a group command.  The return status is the exit status of
	      list.

       ((expression))
	      The expression is evaluated according to the rules described below  under	 ARITHMETIC  EVALUA�
	      TION.   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  expres�
	      sion.   Expressions  are	composed  of the primaries described below under CONDITIONAL EXPRES�
	      SIONS.  Word splitting and pathname expansion are not performed on the words  between  the  [[
	      and  ]]; tilde expansion, parameter and variable expansion, arithmetic expansion, command sub�
	      stitution, 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 execute 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
	      omitted, the for command executes list once for each positional parameter	 that  is  set	(see
	      PARAMETERS  below).   The	 return status is the exit status of the last command that executes.
	      If the expansion of the items following in results in an empty list, no commands are executed,
	      and the return status is 0.

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

       select name [ in word ] ; do list ; done
	      The list of words following in is expanded, generating a list of items.  The set	of  expanded
	      words is printed on the standard error, each preceded by a number.  If the in word is omitted,
	      the positional parameters are printed (see PARAMETERS below).  The PS3  prompt  is  then	dis�
	      played  and a line read from the standard input.	If the line consists of a number correspond�
	      ing 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 or return 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 pathname 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 status 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 interactive_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  interac�
       tive_comments  option  enabled  does  not  allow	 comments.  The interactive_comments option is on by
       default in interactive 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 history expansion character, usu�
       ally !, 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 char�
       acter that follows, with the exception of <newline>.  If a \<newline> pair appears, and the backslash
       is not itself quoted, the \<newline> is treated as a line continuation (that is, it is  removed	from
       the input stream and effectively ignored).

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

       Enclosing characters in double quotes preserves the  literal  value  of	all  characters	 within	 the
       quotes,	with  the  exception  of  $,  `, and \.	 The characters $ and ` retain their special meaning
       within double quotes.  The backslash retains its special meaning only when followed  by	one  of	 the
       following characters: $, `, ", \, or <newline>.	A double quote may be quoted within double quotes by
       preceding it with a backslash.

       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 pre�
       sent, 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 character whose ASCII code is the octal value nnn (one to three digits)
	      \xnnn  the character whose ASCII code is the hexadecimal value nnn (one to three digits)

       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 current locale is C or POSIX, the dollar sign is ignored.  If the
       string is translated and replaced, the replacement is double-quoted.

PARAMETERS
       A parameter is an entity that stores values.  It can be a name, a number, or one of the special char�
       acters  listed  below  under Special Parameters.	 For the shell's purposes, a variable is a parameter
       denoted by a name.

       A parameter is set if it has been assigned a value.  The null string is a valid value.  Once a  vari�
       able  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, command substitution, arithmetic expansion, and quote removal (see
       EXPANSION below).  If the variable has its integer attribute set (see declare below in SHELL  BUILTIN
       COMMANDS)  then	value  is subject to arithmetic expansion even if the $((...)) expansion is not used
       (see Arithmetic Expansion below).  Word splitting is not performed, with the  exception	of  "$@"  as
       explained below under Special Parameters.  Pathname expansion is not performed.

   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  reas�
       signed  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 single word with the value of each parameter separated  by	 the
	      first  character	of  the	 IFS  special variable.	 That is, "$*" is equivalent to "$1c$2c...",
	      where c is the first character of the value of the IFS variable.	If IFS is unset, the parame�
	      ters  are	 separated by spaces.  If IFS is null, the parameters are joined without intervening
	      separators.
       @      Expands to the positional parameters, starting from one.	When  the  expansion  occurs  within
	      double quotes, each parameter expands to a separate word.	 That is, "$@" is equivalent to "$1"
	      "$2" ...	When there are no positional parameters, "$@" 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 invocation, by the set builtin command,
	      or those set by the shell itself (such as the -i option).
       $      Expands to the process ID of the shell.  In a () subshell, it expands to the process ID of the
	      current shell, not the subshell.
       !      Expands to the process ID of the most recently executed background (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 commands, $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 exe�
	      cuted, 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:

       PPID   The process ID of the shell's parent.  This variable is readonly.
       PWD    The current working directory as set by the cd command.
       OLDPWD The previous working directory as set by the cd command.
       REPLY  Set to the line of input read by the read builtin command when no arguments are supplied.
       UID    Expands  to  the	user ID of the current user, initialized at shell startup.  This variable is
	      readonly.
       EUID   Expands to the effective user ID of the current user,  initialized  at  shell  startup.	This
	      variable is readonly.
       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.
       BASH   Expands to the full file name used to invoke this instance of bash.
       BASH_VERSION
	      Expands to a string describing the version of 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.

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

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

       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.

       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 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.

       FUNCNAME
	      The  name	 of  any currently-executing shell function.  This variable exists only when a shell
	      function is executing.  Assignments to FUNCNAME have no effect and return an error status.  If
	      FUNCNAME is unset, it loses its special properties, even if it is subsequently reset.

       DIRSTACK
	      An  array	 variable (see Arrays below) containing the current contents of the directory stack.
	      Directories appear in the stack in the order they are displayed by the dirs builtin.   Assign�
	      ing  to members of this array variable may be used to modify directories already in the stack,
	      but the pushd and popd builtins must be used to add and  remove  directories.   Assignment  to
	      this  variable will not change the current directory.  If DIRSTACK is unset, it loses its spe�
	      cial properties, even if it is subsequently reset.

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

       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).

       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.

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

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

       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 envi�
	      ronment when bash starts up, each shell option in the list will be enabled before reading	 any
	      startup files.  This variable is read-only.

       COMP_WORDS
	      An array variable (see Arrays below) consisting of the individual words in the current command
	      line.  This variable is available only in shell functions invoked by the programmable  comple�
	      tion facilities (see Programmable Completion below).

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

       COMP_POINT
	      The index of the current cursor position relative to the beginning 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	programmable  completion  facilities  (see  Programmable  Completion
	      below).

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

       IFS    The Internal Field Separator that is used for word splitting  after  expansion  and  to  split
	      lines  into  words  with	the  read builtin command.  The default value is ``<space><tab><new�
	      line>''.
       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:.''.
       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.
       CDPATH The search path for the cd command.  This is a colon-separated list of  directories  in  which
	      the  shell  looks	 for destination directories specified by the cd command.  A sample value is
	      ``.:~:/usr''.
       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.
       MAIL   If this parameter is set to a file name and the MAILPATH variable is not set, bash informs the
	      user of the arrival of mail in the specified file.
       MAILCHECK
	      Specifies how often (in seconds) bash checks for mail.  The default is 60 seconds.  When it is
	      time to check for mail, the shell does so before displaying the primary prompt.  If this vari�
	      able 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	mes�
	      sage  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 location of the user mail files	that
	      it uses is system dependent (e.g., /var/mail/$USER).
       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	com�
	      mand bash displays during an execution trace.  The first character of PS4 is replicated multi�
	      ple times, as necessary, to indicate multiple levels of indirection.  The default is ``+ ''.
       TIMEFORMAT
	      The value of this parameter is used as a format string specifying how the	 timing	 information
	      for  pipelines  prefixed	with  the  time	 reserved word should be displayed.  The % character
	      introduces 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	dis�
	      played.  A trailing newline is added when the format string is displayed.

       HISTSIZE
	      The  number  of  commands to remember in the command history (see HISTORY below).	 The default
	      value is 500.

       HISTFILE
	      The name of the file in which command history is saved (see HISTORY below).  The default value
	      is  ~/.bash_history.   If	 unset,	 the  command history is not saved when an interactive shell
	      exits.

       HISTFILESIZE
	      The maximum number of lines contained in the history file.  When this variable is	 assigned  a
	      value,  the  history  file  is truncated, 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 writ�
	      ing it when an interactive shell exits.

       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.

       LANG   Used  to determine the locale category for any category not specifically selected with a vari�
	      able starting with LC_.

       LC_ALL This variable overrides the value of LANG and any other LC_ variable specifying a locale cate�
	      gory.

       LC_COLLATE
	      This  variable determines the collation order used when sorting the results of pathname expan�
	      sion, and determines the behavior of range expressions,  equivalence  classes,  and  collating
	      sequences within pathname expansion and pattern matching.

       LC_CTYPE
	      This  variable  determines  the  interpretation  of  characters  and the behavior of character
	      classes within pathname expansion and pattern matching.

       LC_MESSAGES
	      This variable determines the locale used to translate double-quoted strings preceded by a $.

       LC_NUMERIC
	      This variable determines the locale category used for number formatting.

       LINES  Used by the select builtin command to determine  the  column  length  for	 printing  selection
	      lists.  Automatically set upon receipt of a SIGWINCH.

       COLUMNS
	      Used  by	the  select  builtin command to determine the terminal width when printing selection
	      lists.  Automatically set upon receipt of a SIGWINCH.

       PROMPT_COMMAND
	      If set, the value is executed as a command prior to issuing each primary prompt.

       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.

       TMOUT  If set to a value greater than zero, the value is interpreted as the number of seconds to wait
	      for  input after issuing the primary prompt.  Bash terminates after waiting for that number of
	      seconds if input does not arrive.

       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 suffix 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 pat�
	      terns in GLOBIGNORE, it is removed from the list of matches.

       INPUTRC
	      The filename for the readline startup file, overriding the default of ~/.inputrc (see READLINE
	      below).

       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, sub�
	      ject  to	the value of HISTIGNORE.  This variable's function is superseded 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.

       HISTIGNORE
	      A	 colon-separated  list of patterns used to decide which command lines should be saved on the
	      history list.  Each pattern is anchored at the beginning of the line and must match  the	com�
	      plete  line  (no implicit `*' is appended).  Each pattern is tested against the line after the
	      checks specified by HISTCONTROL are applied.  In addition to the normal shell pattern matching
	      characters,  `&' matches the previous history line.  `&' may be escaped using a backslash; the
	      backslash is removed before attempting a match.  The second and subsequent lines of  a  multi-
	      line  compound command are not tested, and are added to the history regardless of the value of
	      HISTIGNORE.

       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, substituting one string for another  in	the  command.	The  default  is  `^'.	 The
	      optional	third character is the character which indicates that the remainder of the line is a
	      comment when found as the first character of a word, normally `#'.  The history comment  char�
	      acter  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.

       HOSTFILE
	      Contains the name of a file in the same format as /etc/hosts that	 should	 be  read  when	 the
	      shell  needs to complete a hostname.  The list of possible hostname completions may be changed
	      while the shell is running; the next time hostname completion is attempted after the value  is
	      changed, bash adds the contents of the new file to the existing list.  If HOSTFILE is set, but
	      has no value, bash attempts to read /etc/hosts to obtain the list of possible hostname comple�
	      tions.  When HOSTFILE is unset, the hostname list is cleared.

       auto_resume
	      This  variable  controls how the shell interacts with the user and job control.  If this vari�
	      able is set, single word simple commands without redirections are treated	 as  candidates	 for
	      resumption  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 analogous 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.

       COMPREPLY
	      An array variable from which bash reads the possible completions generated by a shell function
	      invoked by the programmable completion facility (see Programmable Completion below).

   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[sub�
       script]=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 [subscript]=string.	 Only string is required.  If the optional brackets and sub�
       script  are  supplied,  that index is assigned to; otherwise the index of the element assigned is the
       last index assigned to by the statement plus one.  Indexing starts at  zero.   This  syntax  is	also
       accepted	 by  the  declare builtin.  Individual array elements may be assigned to using the name[sub�
       script]=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  sepa�
       rate 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 expansion is the number of
       elements in the array.  Referencing an array variable without a subscript is equivalent to  referenc�
       ing element zero.

       The  unset  builtin  is	used to destroy arrays.	 unset name[subscript] destroys 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
       substitution, arithmetic expansion, word splitting, and pathname expansion.

       The order of expansions is: brace expansion, tilde  expansion,  parameter,  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 available: 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 generated.  This mechanism is  simi�
       lar to pathname expansion, but the filenames 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 characters special to other  expan�
       sions are preserved in the result.  It is strictly textual.  Bash does not apply any syntactic inter�
       pretation 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 considered eligible for brace expansion.

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

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

       Brace expansion introduces a slight incompatibility with historical versions  of	 sh.   sh  does	 not
       treat  opening  or closing braces specially when they appear as part of a word, and preserves them in
       the output.  Bash removes braces from words as a consequence of brace expansion.	 For example, a word
       entered to sh as file{1,2} appears identically in the output.  The same word is output as file1 file2
       after expansion by bash.	 If strict compatibility with sh is desired, start bash with the  +B  option
       or  disable brace expansion with the +B option to the set command (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  directory  of	 the
       user  executing	the  shell is substituted instead.  Otherwise, the tilde-prefix is replaced with the
       home directory associated with the specified login name.

       If the tilde-prefix is a `~+', the value of the shell variable PWD replaces the tilde-prefix.  If the
       tilde-prefix is a `~-', the value of the shell variable OLDPWD, if it is set, is substituted.  If the
       characters 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	 argument.   If	 the
       characters  following the tilde in the tilde-prefix consist 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 immediately following a : or  =.	  In
       these  cases, tilde expansion is also performed.	 Consequently, one may use file names with tildes in
       assignments to PATH, MAILPATH, and CDPATH, and the shell assigns the expanded value.

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

       When braces are used, the matching ending brace is the first `}' not escaped by a backslash or within
       a quoted string, and not within an embedded arithmetic expansion, command substitution,	or  paramter
       expansion.

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

       If  the	first  character  of  parameter	 is an exclamation point, a level of variable indirection is
       introduced.  Bash uses the value of the variable 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, parameter expansion, command substi�
       tution, and arithmetic expansion.  When not performing substring expansion, bash tests for a  parame�
       ter that is unset or null; omitting the colon results in a test only for a parameter that is unset.

       ${parameter:-word}
	      Use  Default  Values.   If  parameter  is unset or null, the expansion of word is substituted.
	      Otherwise, the value of parameter is substituted.
       ${parameter:=word}
	      Assign Default Values.  If parameter is unset or null, the expansion of word  is	assigned  to
	      parameter.   The	value  of  parameter is then substituted.  Positional parameters and special
	      parameters may not be assigned to in this way.
       ${parameter:?word}
	      Display Error if Null or Unset.  If parameter is null or unset, the expansion of	word  (or  a
	      message to that effect if word is not present) is written to the standard error and the shell,
	      if it is not interactive, exits.	Otherwise, the value of parameter is substituted.
       ${parameter:+word}
	      Use Alternate Value.  If parameter is null or unset, nothing  is	substituted,  otherwise	 the
	      expansion of word is substituted.
       ${parameter:offset}
       ${parameter:offset:length}
	      Substring	 Expansion.  Expands to up to length characters of parameter starting at the charac�
	      ter specified by offset.	If length is omitted, expands to the substring of parameter starting
	      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  begin�
	      ning  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
	      unless the positional parameters are used, in which case the indexing starts at 1.

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

       ${#parameter}
	      The length in characters of the value of parameter is substituted.  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 oper�
	      ation 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 opera�
	      tion is applied to each member of the array in turn, and the expansion is the resultant  list.

       ${parameter%word}
       ${parameter%%word}
	      The  word	 is  expanded  to  produce  a pattern just as in pathname expansion.  If the pattern
	      matches a trailing portion of the expanded value of parameter, then the result of	 the  expan�
	      sion 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/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 pattern 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 / fol�
	      lowing pattern may be omitted.  If parameter is @ or *, the substitution operation is  applied
	      to  each	positional parameter in turn, and the expansion is the resultant list.	If parameter
	      is an array variable 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 command name.  There are two
       forms:


	      $(command)
       or
	      `command`

       Bash performs the expansion by executing command and replacing  the  command  substitution  with	 the
       standard	 output	 of  the  command,  with  any  trailing newlines deleted.  Embedded newlines are not
       deleted, but they may be removed during word splitting.	The 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 substitution.  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  back�
       quotes with backslashes.

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

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

	      $((expression))

       The expression is treated as if it were within double quotes, but a double quote inside the parenthe�
       ses is not treated specially.  All tokens 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 output 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 provide input for list.	 If the <(list) form is used, the file passed as an argument
       should be read to obtain the output of list.

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

   Word Splitting
       The shell scans the results of parameter expansion, command substitution,  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 whitespace, along with any adjacent IFS  whitespace
       characters,  delimits  a	 field.	 A sequence of IFS whitespace characters is also treated as a delim�
       iter.  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 disabled, the word is left unchanged.  If the nullglob option
       is set, and no matches are found, the word is removed.  If the shell option  nocaseglob	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	characters  separated  by  a  hyphen
	      denotes  a range expression; any character 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 character in the set.  A ] may be matched by including it as the first character
	      in the set.

	      Within  [ and ], character classes can be specified using the syntax [:class:], where class is
	      one of the following classes defined in the POSIX.2 standard:
	      alnum alpha ascii blank cntrl digit graph lower print punct space upper xdigit
	      A character class matches any character belonging to that class.

	      Within [ and ], an equivalence class can be specified using the syntax  [=c=],  which  matches
	      all  characters with the same collation weight (as defined by the current locale) as the char�
	      acter c.

	      Within [ and ], the syntax [.symbol.] matches the collating symbol symbol.

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

	      ?(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 characters \, ', 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  inter�
       preted by the shell.  Redirection may also be used to open and close files for the current shell exe�
       cution environment.  The following redirection operators may precede or appear anywhere within a sim�
       ple  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 omitted, and the first  character  of
       the  redirection operator is <, the redirection 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 descriptions, unless otherwise noted, is
       subjected to brace expansion, tilde expansion, parameter expansion, command substitution,  arithmetic
       expansion,  quote  removal,  pathname  expansion, and word splitting.  If it expands to more than one
       word, bash reports an error.

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 > dirlist

       directs only the standard output to file dirlist, because the standard error was duplicated as  stan�
       dard output before the standard output was redirected to dirlist.

       Bash handles several filenames specially when they are used in redirections, as described in the fol�
       lowing table:

	      /dev/fd/fd
		     If fd is a valid integer, file descriptor fd is duplicated.
	      /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,
		     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,
		     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 expansion of word to be	 opened	 for
       reading on file descriptor n, or the standard input (file descriptor 0) if n is not specified.

       The general format for redirecting input is:

	      [n]<word

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

       The general format for redirecting output is:

	      [n]>word

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

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

       The general format for appending output is:

	      [n]>>word


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

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

	      &>word
       and
	      >&word

       Of the two forms, the first is preferred.  This is semantically equivalent to

	      >word 2>&1

   Here Documents
       This type of redirection instructs the shell to read input from the current source until a line	con�
       taining 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 as follows:

	      <<[-]word
		      here-document
	      delimiter

       No parameter expansion, command substitution, arithmetic expansion, or  pathname	 expansion  is	per�
       formed  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, command substitution, and arithmetic expansion.
       In the latter case, the character sequence \<newline> is ignored, and \ must be	used  to  quote	 the
       characters \, $, and `.

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

   Duplicating File Descriptors
       The redirection operator

	      [n]<&word

       is  used	 to  duplicate	input  file  descriptors.   If	word expands to one or more digits, the file
       descriptor denoted by n is made to be a copy of that file descriptor.  If the digits in word  do	 not
       specify	a  file descriptor open for input, a redirection error occurs.	If word 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 redirection 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.

   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	cre�
       ated.

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 expansion.

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

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

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

       The rules concerning the definition and use of aliases are somewhat confusing.  Bash always reads  at
       least  one  complete  line  of  input before executing any of the commands on that line.	 Aliases are
       expanded when a command is read, not when it is executed.  Therefore, an alias  definition  appearing
       on  the	same line as another command does not take effect until the next line of input is read.	 The
       commands following the alias definition on that line are not affected by the new alias.	This  behav�
       ior 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  command.
       As  a  consequence, aliases defined in a function are not available until after that function is exe�
       cuted.  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 interpret them (contrast this with the execution of a
       shell  script).	 When  a  function  is executed, the arguments to the function become the positional
       parameters during its execution.	 The special parameter # is updated to reflect	the  change.   Posi�
       tional  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 environment are identical between  a
       function	 and  its  caller  with	 the  exception that the DEBUG trap (see the description of the trap
       builtin under SHELL BUILTIN COMMANDS below) is not inherited.

       Variables local to the function may be declared with the local builtin  command.	  Ordinarily,  vari�
       ables 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 function call.  When a function completes, the values  of  the  posi�
       tional  parameters and the special parameter # are restored to the values they had prior to the func�
       tion'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 typeset 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 recursive 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 long integers	with  no  check	 for
       overflow,  though  division  by 0 is trapped and flagged as an error.  The operators and their prece�
       dence and associativity are the same as in the C	 language.   The  following  list  of  operators  is
       grouped	into  levels  of  equal-precedence  operators.	The levels are listed in order of decreasing
       precedence.

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

       Shell variables are allowed as operands; parameter expansion is performed 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 arithmetic 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 represent�
       ing the arithmetic base, and n is a number in that base.	 If base# is omitted, then base 10 is  used.
       The  digits greater than 9 are represented by the lowercase letters, the uppercase letters, _, and @,
       in that order.  If base is less than or equal to 36, lowercase and  uppercase  letters  may  be	used
       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 primaries  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.
       file1 -ot file2
	      True if file1 is older than file2.
       file1 -ef file2
	      True if file1 and file2 have the same device and inode numbers.
       -o optname
	      True if shell option optname is enabled.	See the list of options under the description of the
	      -o option to the set builtin below.
       -z string
	      True if the length of string is zero.
       -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 ==.
       string1 != string2
	      True if the strings are not equal.
       string1 < string2
	      True if string1 sorts before string2 lexicographically in the current locale.
       string1 > string2
	      True if string1 sorts after string2 lexicographically in the current locale.
       arg1 OP arg2
	      OP  is  one of -eq, -ne, -lt, -le, -gt, or -ge.  These arithmetic binary operators return true
	      if arg1 is equal to, not equal to, less than, less than or equal to, greater than, or  greater
	      than or equal to arg2, respectively.  Arg1 and arg2 may be positive or negative integers.

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

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

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

       3.     Redirections are performed as described above under REDIRECTION.

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

       If  no  command	name results, the variable assignments affect the current shell environment.  Other�
       wise, the variables are added to the environment of the executed command and do not affect  the	cur�
       rent shell environment.	If any of the assignments attempts to assign a value to a readonly variable,
       an error occurs, and the command exits with a non-zero status.

       If no command name results, redirections are performed, but do not affect the current shell  environ�
       ment.  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 expansions 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 sub�
       stitutions, 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 containing an executable file by that name.  Bash uses a hash
       table to remember the full pathnames of executable files	 (see  hash  under  SHELL  BUILTIN  COMMANDS
       below).	 A  full  search of the directories in PATH is performed only if the command is not found in
       the hash table.	If the search is unsuccessful, the shell prints an error message and returns an exit
       status of 127.

       If  the search is successful, or if the command name contains one or more slashes, the shell executes
       the named program in a separate execution environment.  Argument 0 is set to the name given, and	 the
       remaining 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 direc�
       tory, it is assumed to be a shell script, a file containing shell commands.  A subshell is spawned to
       execute	it.   This  subshell  reinitializes itself, so that the effect is as if a new shell had been
       invoked to handle the script, with the exception that the locations of  commands	 remembered  by	 the
       parent (see hash below under SHELL BUILTIN COMMANDS) are retained by the child.

       If  the program is a file beginning with #!, the remainder of the first line specifies an interpreter
       for the program.	 The shell executes the specified interpreter on operating systems that do not	han�
       dle this executable 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 following:


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

       �      the current working directory as set by cd, pushd, or popd, or inherited by the shell at invo�
	      cation

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

       �      current traps set by trap

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

       �      shell functions defined during execution or inherited from the shell's parent in the  environ�
	      ment

       �      options enabled at invocation (either by default or with command-line arguments) or by set

       �      options enabled by shopt

       �      shell aliases defined with alias

       �      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 consists of the following.  Unless otherwise noted, the values
       are inherited from the shell.


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

       �      the current working directory

       �      the file creation mode mask

       �      shell  variables	marked	for export, along with variables exported for the command, passed in
	      the environment

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

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

       Command substitution and asynchronous commands are invoked in a subshell environment that is a dupli�
       cate 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 invoked as part of a
       pipeline are also executed in a subshell environment.  Changes made to the subshell environment	can�
       not affect the shell's execution environment.

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

       The shell provides several ways to manipulate the environment.  On invocation, the  shell  scans	 its
       own  environment	 and creates a parameter for each name found, automatically marking it for export to
       child processes.	 Executed commands inherit the environment.  The  export  and  declare	-x  commands
       allow  parameters  and  functions to be added to and deleted from the environment.  If the value of a
       parameter in the environment is modified, the new value becomes part of	the  environment,  replacing
       the  old.  The environment inherited by any executed command consists of the shell's initial environ�
       ment, whose values may be modified 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
       environment 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 environment.

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

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

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

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

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

SIGNALS
       When  bash  is  interactive, in the absence of any traps, it ignores SIGTERM (so that kill 0 does not
       kill an interactive shell), and SIGINT is caught and handled (so that the wait builtin is  interrupt�
       ible).  In all cases, bash ignores SIGQUIT.  If job control is in effect, bash ignores SIGTTIN, SIGT�
       TOU, 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 effect, asynchronous commands ignore SIGINT and SIGQUIT as
       well.  Commands run as a result of command substitution ignore  the  keyboard-generated	job  control
       signals SIGTTIN, SIGTTOU, and SIGTSTP.

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

       If the huponexit shell option has been set with shopt, bash sends a SIGHUP to all jobs when an inter�
       active 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 command 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 status greater than 128, immediately after which the
       trap is executed.

JOB CONTROL
       Job control refers to the ability to selectively stop (suspend) the execution of processes  and	con�
       tinue  (resume)	their  execution  at  a	 later point.  A user typically employs this facility via an
       interactive interface supplied jointly by the system's terminal driver and bash.

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

	      [1] 25647

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

       To facilitate the implementation of the user interface to job control, the operating system maintains
       the  notion  of	a current terminal process group ID.  Members of this process group (processes whose
       process group ID is equal to the current terminal process group ID) receive  keyboard-generated	sig�
       nals  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.  Back�
       ground processes which attempt to read from (write to) the terminal are sent a SIGTTIN (SIGTTOU) sig�
       nal by the terminal driver, which, unless caught, suspends the process.

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

       There are a number of ways to refer to a job in the shell.  The character % 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 example,  %ce  refers  to  a
       stopped	ce  job.   If a prefix matches more than one job, bash reports an error.  Using %?ce, on the
       other hand, refers to any job containing the string ce in its command line.  If the substring matches
       more  than  one job, bash reports an 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 pertaining 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.

       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 intervening command, the shell does not print another warning, and the  stopped  jobs	 are  termi�
       nated.

PROMPTING
       When  executing	interactively,	bash displays the primary prompt PS1 when it is ready to read a com�
       mand, 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")
	      \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
	      \u     the username of the current user
	      \v     the version of bash (e.g., 2.00)
	      \V     the release of bash, version + patchlevel (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 HIS�
       TORY below), while the command number is the position in the sequence of commands executed during the
       current shell session.  After the string is decoded, it is expanded via parameter expansion,  command
       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 interactive shell, unless the  --noedit�
       ing  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.  Similarly, meta keys are denoted by M-key, so M-x means Meta-X.
       (On keyboards 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 com�
       mand 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  accumu�
       lated  into  one unit, which can be yanked all at once.	Commands which do not kill text separate the
       chunks of text on the kill ring.

   Readline Initialization
       Readline is customized by putting commands in an initialization file (the inputrc file).	 The name of
       this file is taken from the value of the INPUTRC variable.  If that variable is unset, the default is
       ~/.inputrc.  When a program which uses the readline library starts up,  the  initialization  file  is
       read,  and  the key bindings and variables are set.  There are only a few basic constructs allowed in
       the readline initialization file.  Blank lines are ignored.  Lines beginning with a #  are  comments.
       Lines  beginning with a $ indicate conditional constructs.  Other lines denote key bindings and vari�
       able 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 universal-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	specified  in  one of two ways: as a symbolic key name, possibly with Meta- or Control- pre�
       fixes, 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 character whose ASCII code is the octal value nnn (one to three digits)
	      \xnnn  the character whose ASCII code is the hexadecimal value nnn (one to three digits)

       When  entering  the text of a macro, single or double quotes must be used to indicate a macro defini�
       tion.  Unquoted text is assumed to be a function 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 modified with the bind builtin	com�
       mand.   The  editing  mode  may	be switched during interactive use by using the -o option to the set
       builtin command (see SHELL BUILTIN COMMANDS below).

   Readline Variables
       Readline has variables that can be used to further customize its behavior.  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	com�
	      mand 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 fash�
	      ion.
       completion-query-items (100)
	      This determines when the user is queried about viewing the number of possible completions gen�
	      erated  by  the possible-completions 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 similar to emacs or vi.  edit�
	      ing-mode can be set to either emacs or vi.
       enable-keypad (Off)
	      When set to On, readline will try to enable the application keypad when it  is  called.	Some
	      systems need this to enable the arrow keys.
       expand-tilde (Off)
	      If set to on, tilde expansion is performed when readline attempts word completion.
       horizontal-scroll-mode (Off)
	      When set to On, makes readline use a single line for display, scrolling the input horizontally
	      on a single screen line when it becomes longer than the screen width rather than wrapping to a
	      new line.
       input-meta (Off)
	      If  set  to  On, readline will enable eight-bit input (that is, it will not strip the high bit
	      from the characters it reads), regardless of what the terminal claims  it	 can  support.	 The
	      name meta-flag is a synonym for this variable.
       isearch-terminators (``C-[C-J'')
	      The string of characters that should terminate an incremental search without subsequently exe�
	      cuting the character as a command.  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-command, 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 displayed with  a	 preceding  asterisk
	      (*).
       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.
       print-completions-horizontally (Off)
	      If set to On, readline will display completions with matches sorted horizontally in alphabeti�
	      cal 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  ring�
	      ing 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 completions.

   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 editing	 mode,	the  terminal  being
	      used, or the application using readline.	The text of the test extends to the end of the line;
	      no characters are required to isolate it.

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

	      term   The  term=	 form may be used to include terminal-specific key bindings, perhaps to bind
		     the key sequences output by the terminal's function keys.	The word on the	 right	side
		     of	 the  =	 is tested against the both full name of the terminal 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 pro�
		     gram using the readline library sets the application name, and an	initialization	file
		     can test for a particular value.  This could be used to bind key sequences to functions
		     useful for a specific program.  For instance, the following command adds a key sequence
		     that quotes the current or previous word in Bash:

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

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

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

       $include
	      This  directive  takes  a	 single filename as an argument and reads commands and bindings from
	      that file.  For example, the following 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, readline 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 Con�
       trol-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 terminate the search and accept the line, thereby executing
       the command from the history list.

       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 accompanying key sequence are unbound by default.  In the  following
       descriptions, 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 (let�
	      ters 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  neces�
	      sary.  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 cur�
	      rent 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 cur�
	      rent line and the point.	This is a non-incremental search.
       yank-nth-arg (M-C-y)
	      Insert  the  first  argument  to the previous command (usually the second word on the previous
	      line) at point.  With an argument n, insert the nth word from the previous command (the  words
	      in the previous command begin with word 0).  A negative argument inserts the nth word from the
	      end of the previous command.
       yank-last-arg (M-., M-_)
	      Insert the last argument to the previous command	(the  last  word  of  the  previous  history
	      entry).	 With	an   argument,	behave	exactly	 like  yank-nth-arg.   Successive  calls  to
	      yank-last-arg move back through the history list, inserting the last argument of each line  in
	      turn.
       shell-expand-line (M-C-e)
	      Expand  the  line as the shell does.  This performs alias and history expansion as well as all
	      of the shell word expansions.  See HISTORY EXPANSION below for a description of history expan�
	      sion.
       history-expand-line (M-^)
	      Perform  history expansion on the current line.  See HISTORY EXPANSION below for a description
	      of history expansion.
       magic-space
	      Perform history expansion on the current line and insert a space.	 See HISTORY EXPANSION below
	      for a description of history expansion.
       alias-expand-line
	      Perform  alias  expansion	 on  the current line.	See ALIASES above for a description of alias
	      expansion.
       history-and-alias-expand-line
	      Perform history and alias expansion on the current line.
       insert-last-argument (M-., M-_)
	      A synonym for yank-last-arg.
       operate-and-get-next (C-o)
	      Accept the current line for execution and fetch the next line relative  to  the  current	line
	      from the history for editing.  Any argument is ignored.

   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 charac�
	      ters 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 cursor is deleted.	By default, this is not bound to a key.
       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.
       upcase-word (M-u)
	      Uppercase the current (or following) word.  With a negative argument, uppercase  the  previous
	      word, but do not move point.
       downcase-word (M-l)
	      Lowercase	 the  current (or following) word.  With a negative argument, lowercase the previous
	      word, but do not move point.
       capitalize-word (M-c)
	      Capitalize the current (or following) word.  With a negative argument, capitalize the previous
	      word, but do not move point.

   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 boundary.	 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 boundaries  are	the  same  as  back�
	      ward-word.
       copy-forward-word
	      Copy  the	 word  following point to the kill buffer.  The word boundaries are the same as for�
	      ward-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 following 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 dig�
	      its, optionally with a leading minus sign, those digits define the argument.  If	the  command
	      is  followed  by	digits, executing universal-argument again ends the numeric argument, but is
	      otherwise ignored.  As a special case, if this command is immediately followed by a  character
	      that  is	neither a digit or minus sign, the argument count for the next command is multiplied
	      by four.	The argument count is initially one, so executing this function the first time makes
	      the argument 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 $), username (if the text begins with ~), hostname
	      (if the text begins with @), or command (including aliases and functions) in turn.  If none of
	      these produces a match, filename completion is attempted.
       possible-completions (M-?)
	      List the possible completions of the text before point.
       insert-completions (M-*)
	      Insert all completions of the text before point that  would  have	 been  generated  by  possi�
	      ble-completions.
       menu-complete
	      Similar  to  complete, but replaces the word to be completed with a single match from the list
	      of possible completions.	Repeated execution of menu-complete steps through the list of possi�
	      ble  completions,	 inserting  each  match in turn.  At the end of the list of completions, the
	      bell is rung (subject to the setting of 0and the original text is restored.  An argument of  n
	      moves  n	positions  forward  in	the list of matches; a negative argument may be used to move
	      backward through the list.  This command is intended to be bound to TAB,	but  is	 unbound  by
	      default.
       delete-char-or-list
	      Deletes  the  character  under  the  cursor  if  not at the beginning or end of the line (like
	      delete-char).  If at the end of the line, behaves identically to	possible-completions.	This
	      command is unbound by default.
       complete-filename (M-/)
	      Attempt filename completion on the text before point.
       possible-filename-completions (C-x /)
	      List the possible completions of the text before point, treating it as a filename.
       complete-username (M-~)
	      Attempt completion on the text before point, treating it as a username.
       possible-username-completions (C-x ~)
	      List the possible completions of the text before point, treating it as a username.
       complete-variable (M-$)
	      Attempt completion on the text before point, treating it as a shell variable.
       possible-variable-completions (C-x $)
	      List the possible completions of the text before point, treating it as a shell variable.
       complete-hostname (M-@)
	      Attempt completion on the text before point, treating it as a hostname.
       possible-hostname-completions (C-x @)
	      List the possible completions of the text before point, treating it as a hostname.
       complete-command (M-!)
	      Attempt  completion  on the text before point, treating it as a command name.  Command comple�
	      tion 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 completions 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 characters 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  posi�
	      tion.
       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 occurrences.
       character-search-backward (M-C-])
	      A	 character is read and point is moved to the previous occurrence of that character.  A nega�
	      tive count searches for subsequent occurrences.
       insert-comment (M-#)
	      The value of the readline comment-begin variable is inserted at the beginning of	the  current
	      line,  and  the  line  is	 accepted as if a newline had been typed.  The default value of com�
	      ment-begin causes this command to make the current line a shell comment.
       glob-expand-word (C-x *)
	      The word before point is treated as a pattern for pathname expansion, and the list of matching
	      file names is inserted, replacing the word.
       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.
       dump-functions
	      Print all of the functions and their key bindings 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-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 output is formatted in such a way that it can be made part
	      of an inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about the current instance of bash.

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

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

       Once  a compspec has been found, it is used to generate the list of matching words.  If a compspec is
       not found, the default bash completion 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 com�
       pletion, the shell variable FIGNORE is used to filter the matches.

       Any completions specified by a filename expansion pattern to the -G option are generated	 next.	 The
       words  generated	 by the pattern need not match the word being completed.  The GLOBIGNORE shell vari�
       able 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 considered.  The string is first split
       using the characters in the IFS special 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 completed, and the matching words become the possible com�
       pletions.

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

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

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

       After  all  of  the  possible  completions  are generated, any filter specified with the -X option is
       applied to the list.  The filter is a pattern 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 matching 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	sup�
       plied to complete when the compspec was defined, 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 completion will be performed if the	 compspec  generates
       no matches.

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 commands (default 500)
       is saved.  The shell stores each command in the history list prior to parameter and  variable  expan�
       sion  (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	variable  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  interactive  shell
       exits,  the  last  $HISTSIZE  lines are copied from the history list to $HISTFILE.  If the histappend
       shell option is enabled (see the description of shopt under SHELL BUILTIN COMMANDS below), the  lines
       are  appended  to the history file, otherwise the history file is overwritten.  If HISTFILE is unset,
       or if the history file is unwritable, the history is not saved.	After saving the history,  the	his�
       tory  file  is  truncated to contain no more than HISTFILESIZE lines.  If HISTFILESIZE is not set, no
       truncation is performed.

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

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

HISTORY EXPANSION
       The shell supports a history expansion feature that is similar to the history expansion in csh.	This
       section describes what syntax features are available.  This feature is enabled by default for  inter�
       active  shells, and can be disabled using the +H option to the set builtin command (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 reading input, so that several metacharacter-separated
       words surrounded by quotes are considered one word.  History expansions are introduced by the appear�
       ance of the history expansion character, which is ! by default.	Only backslash (\) and single quotes
       can quote the history expansion character.

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

       The shell allows control of the various characters used by the history expansion mechanism  (see	 the
       description of histchars above under Shell Variables).

   Event Designators
       An event designator is a reference to a command line entry in the history 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 trailing ? may be omitted if string
	      is followed immediately by a newline.
       ^string1^string2^
	      Quick substitution.  Repeat the last command, replacing string1 with string2.   Equivalent  to
	      ``!!:s/string1/string2/'' (see Modifiers below).
       !#     The entire command line typed so far.

   Word Designators
       Word designators are used to select desired words from the event.  A : separates the event specifica�
       tion 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 separated 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 modi�
       fiers, each preceded by a `:'.

       h      Remove a trailing file name component, leaving only the head.
       t      Remove all leading file name components, leaving the tail.
       r      Remove a trailing suffix of the form .xxx, leaving the basename.
       e      Remove all but the trailing suffix.
       p      Print the new command but do not execute it.
       q      Quote the substituted words, escaping further substitutions.
       x      Quote the substituted words as with q, but break into words at blanks and newlines.
       s/old/new/
	      Substitute  new  for the first occurrence of old in the event line.  Any delimiter can be used
	      in place of /.  The final delimiter is optional if it is the last character of the event line.
	      The  delimiter  may be quoted in old and new with a single backslash.  If & appears in new, it
	      is replaced by old.  A single backslash will quote the &.	 If old is null, it is	set  to	 the
	      last  old substituted, or, if no previous history substitutions 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 environment and return  the	exit
	      status of the last command executed from filename.  If filename does not contain a slash, file
	      names in PATH are used to find the directory containing filename.	 The file  searched  for  in
	      PATH  need  not  be  executable.	 When  bash  is	 not in posix mode, the current directory is
	      searched if no file is found in PATH.  If the sourcepath option to the shopt  builtin  command
	      is turned off, the PATH is not searched.	If any arguments are supplied, they become the posi�
	      tional parameters	 when  filename	 is  executed.	 Otherwise  the	 positional  parameters	 are
	      unchanged.  The return status is the status of the last command exited within the script (0 if
	      no commands are executed), and false if filename is not found or cannot be read.

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

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

       bind [-m keymap] [-lpsvPSV]
       bind [-m keymap] [-q function] [-u function] [-r keyseq]
       bind [-m keymap] -f filename
       bind [-m keymap] -x keyseq:shell-command
       bind [-m keymap] keyseq:function-name
	      Display current readline key and function bindings, or bind a key sequence to a readline func�
	      tion or macro.  The binding syntax accepted is identical to that of .inputrc, but each binding
	      must be passed as a separate argument; e.g.,  '"\C-x\C-r":  re-read-init-file'.	Options,  if
	      supplied, have the following meanings:
	      -m keymap
		     Use  keymap as the keymap to be affected by the subsequent bindings.  Acceptable keymap
		     names are emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, vi-move,  vi-command,	 and
		     vi-insert.	 vi is equivalent to vi-command; emacs is equivalent to emacs-standard.
	      -l     List the names of all readline functions.
	      -p     Display readline function names and bindings in such a way that they can be re-read.
	      -P     List current readline function names and bindings.
	      -v     Display readline variable names and values in such a way that they can be re-read.
	      -V     List current readline variable names and values.
	      -s     Display  readline	key  sequences bound to macros and the strings they output in such a
		     way that they can be re-read.
	      -S     Display readline key sequences bound to macros and the strings they output.
	      -f filename
		     Read key bindings from filename.
	      -q function
		     Query about which keys invoke the named function.
	      -u function
		     Unbind all keys bound to the named function.
	      -r keyseq
		     Remove any current binding for keyseq.
	      -x keyseq:shell-command
		     Cause shell-command to be executed whenever keyseq is entered.

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

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

       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
	      functionality  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 [-LP] [dir]
	      Change the current directory to dir.  The variable HOME is  the  default	dir.   The  variable
	      CDPATH  defines the search path for the directory containing dir.	 Alternative directory names
	      in CDPATH are separated by a colon (:).  A null directory name in CDPATH is the  same  as	 the
	      current  directory, i.e., ``.''.	If dir begins with a slash (/), then CDPATH is not used. The
	      -P option says to use the physical directory structure instead  of  following  symbolic  links
	      (see also the -P option to the set builtin command); the -L option forces symbolic links to be
	      followed.	 An argument of - is equivalent to $OLDPWD.  The return value is true if the  direc�
	      tory 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 utili�
	      ties.  If either the -V or -v option is supplied, a description of command is printed.  The -v
	      option  causes  a single word indicating the command or file name used to invoke command to be
	      displayed; the -V option produces a more verbose description.  If the -V or -v option is	sup�
	      plied, the exit status is 0 if command was found, and 1 if not.  If neither option is supplied
	      and an error occurred or command cannot be found, the exit status is 127.	 Otherwise, the exit
	      status of the command builtin is the exit status of command.

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

	      The matches will be generated in the same way as if the programmable completion code had	gen�
	      erated  them  directly from a completion specification with the same flags.  If word is speci�
	      fied, only those completions matching word will be displayed.

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

       complete [-abcdefjkvu] [-o comp-option] [-A action] [-G globpat] [-W wordlist] [-P prefix]  [-S	suf�
       fix]
	      [-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 specification for	 each  name,
	      or, if no names are supplied, all completion specifications.

	      The  process  of applying these completion specifications when word completion is attempted is
	      described above under Programmable 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
	      expansion before the complete builtin is invoked.
	      -o comp-option
		      The comp-option controls several aspects of the compspec's behavior beyond the  simple
		      generation of completions.  comp-option may be one of:
		      default Use readline's default completion if the compspec generates no matches.
		      dirnames
			      Perform directory name completion if the compspec generates no matches.
		      filenames
			      Tell  readline  that  the	 compspec generates filenames, so it can perform any
			      filename-specific processing (like adding a slash to directory names  or	sup�
			      pressing trailing spaces).  Intended to be used with shell functions.
	      -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.
		      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.
		      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 specified as -v.
	      -G globpat
		      The  filename  expansion	pattern globpat is expanded to generate the possible comple�
		      tions.
	      -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 completed.
	      -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 completions 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 generated by the preceding options and arguments, and  each	com�
		      pletion 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 completion 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 argument, an attempt is made to remove a completion specification
	      for a name for which no specification exists, or an error occurs adding a completion  specifi�
	      cation.

       continue [n]
	      Resume  the next iteration of the enclosing for, while, until, or select loop.  If n is speci�
	      fied, resume at the nth enclosing loop.  n must be >= 1.	If n is greater than the  number  of
	      enclosing	 loops,	 the  last  enclosing  loop (the ``top-level'' loop) is resumed.  The return
	      value is 0 unless the shell is not executing a loop when continue is executed.

       declare [-afFirx] [-p] [name[=value]]
       typeset [-afFirx] [-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  defini�
	      tions; only the function name and attributes are printed.	 The -F option implies -f.  The fol�
	      lowing 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 evaluation (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  assign�
		     ment statements or unset.
	      -x     Mark names for export to subsequent commands via the environment.

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

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

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

       disown [-ar] [-h] [jobspec ...]
	      Without options, each jobspec is removed from the table of active jobs.  If the -h  option  is
	      given, each jobspec is not removed from the table, but is marked so that SIGHUP is not sent to
	      the job if the shell receives a SIGHUP.  If no jobspec is present, and neither the -a nor	 the
	      -r  option  is  supplied,	 the  current job is used.  If no jobspec is supplied, the -a option
	      means to remove or mark all jobs; the -r option without a jobspec 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,  interpre�
	      tation  of  the following backslash-escaped characters is enabled.  The -E option disables the
	      interpretation of these escape characters, even on  systems  where  they	are  interpreted  by
	      default.	 The  xpg_echo shell option may be used to dynamically determine whether or not echo
	      expands these escape characters by default.  echo does not interpret -- to  mean	the  end  of
	      options.	echo interprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress trailing newline
	      \e     an escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal tab
	      \v     vertical tab
	      \\     backslash
	      \nnn   the character whose ASCII code is the octal value nnn (one to three digits)
	      \xnnn  the character whose ASCII code is the hexadecimal value nnn (one to three digits)

       enable [-adnps] [-f filename] [name ...]
	      Enable  and  disable  builtin shell commands.  Disabling a builtin allows a disk command which
	      has the same name as a shell builtin to be executed without specifying a full  pathname,	even
	      though  the  shell  normally  searches for builtins before disk commands.	 If -n is used, each
	      name is disabled; otherwise, names are enabled.  For example, to use the test binary found via
	      the PATH instead of the shell builtin version, run ``enable -n test''.  The -f option means to
	      load the new builtin command name from shared object filename, on systems that support dynamic
	      loading.	The -d option will delete a builtin previously loaded with -f.	If no name arguments
	      are given, or if the -p option is supplied, a list of shell  builtins  is	 printed.   With  no
	      other  option  arguments, the list consists of all enabled shell builtins.  If -n is supplied,
	      only disabled builtins are printed.   If	-a  is	supplied,  the	list  printed  includes	 all
	      builtins, with an indication 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 command.  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
	      beginning	 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 cannot 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 environment of subsequently executed
	      commands.	 If the -f option is given, the names refer to functions.  If no names are given, or
	      if the -p option is supplied, a list of all names that are exported in this shell is  printed.
	      The  -n  option  causes  the  export  property to be removed from the named variables.  export
	      returns an exit status of 0 unless an invalid option is encountered, one of the names is not a
	      valid shell variable name, or -f is supplied with a name that is not a function.

       fc [-e ename] [-nlr] [first] [last]
       fc -s [pat=rep] [cmd]
	      Fix  Command.   In the first form, a range of commands from first to last is selected from the
	      history list.  First and last may be specified as a string (to locate the last command  begin�
	      ning with that string) or as a number (an index into the history list, where a negative number
	      is used as an offset from the current command number).  If last is not specified it is set  to
	      the  current  command  for  listing (so that ``fc -l -10'' prints the last 10 commands) and to
	      first otherwise.	If first is not specified 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.	Oth�
	      erwise, 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 complete, the edited commands
	      are echoed and executed.

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

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

       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 con�
	      trol enabled, if jobspec does not specify 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 parameters.  optstring contains the
	      option characters to be recognized; if a character is followed  by  a  colon,  the  option  is
	      expected to have an argument, which should be separated from it by white space.  The colon and
	      question mark characters may not be used as option  characters.	Each  time  it	is  invoked,
	      getopts  places  the  next option in the shell variable name, initializing name if it does not
	      exist, and the index of the next argument to be processed into the variable OPTIND.  OPTIND is
	      initialized to 1 each time the shell or a shell script is invoked.  When an option requires an
	      argument, getopts places that argument into the variable OPTARG.	The  shell  does  not  reset
	      OPTIND  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 return value greater	 than  zero.
	      OPTIND is set to the index of the first non-option argument, and name is set to ?.

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

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

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

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

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

       hash [-r] [-p filename] [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.   If  no  arguments are given, information about remembered commands is
	      printed.	The return status is true unless a name is not found or an invalid  option  is	sup�
	      plied.

       help [-s] [pattern]
	      Display  helpful	information  about  builtin  commands.	 If pattern is specified, help gives
	      detailed help on all commands matching pattern; otherwise help for all the builtins and  shell
	      control  structures  is printed.	The -s option restricts the information displayed to a short
	      usage synopsis.  The return status is 0 unless no command matches pattern.

       history [n]
       history -c
       history -d offset
       history -anrw [filename]
       history -p arg [arg ...]
       history -s arg [arg ...]
	      With no options, display the command history list with line numbers.  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 HISTFILE is  used.   Options,
	      if supplied, have the following meanings:
	      -c     Clear the history list by deleting all the entries.
	      -d offset
		     Delete the history entry at position offset.
	      -a     Append the ``new'' history lines (history lines entered since the beginning of the cur�
		     rent bash session) to the history file.
	      -n     Read the history lines not already read from the history file into the current  history
		     list.   These are lines appended to the history file since the beginning of the current
		     bash session.
	      -r     Read the contents of the history file and use them as the current history.
	      -w     Write the current history to the history file, overwriting the history file's contents.
	      -p     Perform  history substitution on the following args and display the result on the stan�
		     dard 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 his�
	      tory 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 following 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 cor�
	      responding  process group ID, and executes command passing it args, returning its exit status.

       kill [-s sigspec | -n signum | -sigspec] [pid | jobspec] ...
       kill -l [sigspec | exit_status]
	      Send the signal named by sigspec or signum to the processes named by pid or jobspec.   sigspec
	      is  either  a  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 assumed.  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
	      either a signal number or the exit status of a process terminated by a signal.   kill  returns
	      true  if	at least one signal was successfully sent, or false if an error occurs or an invalid
	      option is encountered.

       let arg [arg ...]
	      Each arg is an arithmetic expression to be evaluated (see ARITHMETIC 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 function 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 fol�
	      lowing meanings:
	      +n     Removes the nth entry counting from the left of the list shown by dirs,  starting	with
		     zero.  For example: ``popd +0'' removes the first directory, ``popd +1'' the second.
	      -n     Removes  the nth entry counting from the right of the list shown by dirs, starting with
		     zero.  For example: ``popd -0'' removes the last directory, ``popd	 -1''  the  next  to
		     last.
	      -n     Suppresses	 the normal change of directory when removing directories from the stack, so
		     that only the stack is manipulated.

	      If the popd command is successful, a dirs is performed as well, and the return  status  is  0.
	      popd  returns  false if an invalid option is encountered, the directory stack is empty, a non-
	      existent 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 format specifications, each of which causes printing of the
	      next successive argument.	 In addition to the standard printf(1) formats, %b causes printf  to
	      expand  backslash escape sequences in the corresponding argument, and %q causes printf to out�
	      put the corresponding argument in a format that can be reused as shell input.

	      The format is reused as necessary to consume all of the arguments.   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 directo�
	      ries  and	 returns  0,  unless the directory stack is empty.  Arguments, if supplied, have the
	      following meanings:
	      +n     Rotates the stack so that the nth directory (counting from the left of the	 list  shown
		     by dirs, starting with zero) is at the top.
	      -n     Rotates  the stack so that the nth directory (counting from the right of the list shown
		     by dirs, starting with zero) is at the top.
	      -n     Suppresses the normal change of directory when adding directories to the stack, so that
		     only the stack is manipulated.
	      dir    Adds  dir	to  the directory stack at the top, making it the new current working direc�
		     tory.

	      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
	      directory stack is empty, a non-existent directory stack element is specified, or	 the  direc�
	      tory change to the specified new current directory fails.

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

       read [-ers] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...]
	      One  line	 is  read from the standard input, 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 intervening sepa�
	      rators  assigned to the last name.  If there are fewer words read from the standard input 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 follow�
	      ing meanings:
	      -a aname
		     The  words	 are assigned to sequential indices of the array variable aname, starting at
		     0.	 aname is unset before any new	values	are  assigned.	 Other	name  arguments	 are
		     ignored.
	      -d delim
		     The  first character of delim is used to terminate the input line, rather than newline.
	      -e     If the standard input is coming from a terminal, readline (see READLINE above) is	used
		     to obtain the line.
	      -n nchars
		     read returns after reading nchars characters rather than waiting for a complete line of
		     input.
	      -p prompt
		     Display prompt, without a trailing newline, 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 backslash is considered to be part
		     of the line.  In particular, a backslash-newline pair may not be used as a line contin�
		     uation.
	      -s     Silent mode.  If input is coming from a terminal, characters 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.

	      If no names are supplied, the line read is assigned to the variable REPLY.  The return code is
	      zero, unless end-of-file is encountered or read times out.

       readonly [-apf] [name ...]
	      The given names are marked readonly; the values of these names may not be	 changed  by  subse�
	      quent  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	exe�
	      cuting  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 execu�
	      tion 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 meanings:
	      -a      Automatically mark variables and functions which are modified or created for export to
		      the environment of subsequent commands.
	      -b      Report the status of terminated background jobs immediately, 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 !.
	      -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 processes run
		      in a separate process group and a line containing their exit status  is  printed	upon
		      their completion.
	      -n      Read  commands  but do not execute them.	This may be used to check a shell script for
		      syntax errors.  This is ignored by interactive shells.
	      -o option-name
		      The option-name can be one of the following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use an emacs-style command line editing interface.  This is enabled by default
			      when  the shell is interactive, unless the shell is started with the --noedit�
			      ing 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 interactive shells.
		      ignoreeof
			      The  effect is as if the shell command ``IGNOREEOF=10'' had been executed (see
			      Shell Variables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.
		      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	cur�
		      rent option settings is displayed on the standard output.
	      -p      Turn  on	privileged  mode.   In	this mode, the $ENV and $BASH_ENV files are not pro�
		      cessed, shell functions are not inherited from  the  environment,	 and  the  SHELLOPTS
		      variable,	 if it appears in the environment, is ignored.	If the shell is started with
		      the effective user (group) id not equal to the real user (group) id, and the -p option
		      is  not supplied, these actions are taken and the effective user id is set to the real
		      user id.	If the -p option is supplied at startup, the effective user id is not reset.
		      Turning  this option off causes the effective user and group ids to be set to the real
		      user and group ids.
	      -t      Exit after reading and executing one command.
	      -u      Treat unset variables as an error when performing parameter 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 expanded value of  PS4,	followed  by
		      the command and its expanded 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 redirection
		      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.   Other�
		      wise, the positional parameters are set to the args, even if some of them begin with a
		      -.
	      -	      Signal the end of options, cause all remaining args to be assigned to  the  positional
		      parameters.   The	 -x  and -v options are turned off.  If there are no args, the posi�
		      tional parameters remain unchanged.

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

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

       shopt [-pqsu] [-o] [optname ...]
	      Toggle  the values of variables controlling optional shell behavior.  With no options, or with
	      the -p option, a list of all settable options is displayed, with an indication of	 whether  or
	      not  each is set.	 The -p option causes output to be displayed in a form that may be reused as
	      input.  Other options have the following meanings:
	      -s     Enable (set) each optname.
	      -u     Disable (unset) each optname.
	      -q     Suppresses normal output (quiet mode); the return status indicates whether the  optname
		     is set or unset.  If multiple optname arguments are given with -q, the return status is
		     zero if all optnames are enabled; non-zero otherwise.
	      -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 display is limited to those options
	      which are set or unset, respectively.  Unless otherwise noted, the shopt options are  disabled
	      (unset) by default.

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

	      The list of shopt options is:

	      cdable_vars
		      If set, an argument to the cd builtin command that is not a directory is assumed to be
		      the name of a variable whose value is the directory to change to.
	      cdspell If set, minor errors in the spelling of a directory component in a cd command will  be
		      corrected.  The errors checked for are transposed characters, a missing character, and
		      one character too many.  If a correction is found, the corrected file name is printed,
		      and the command proceeds.	 This option is only used by interactive shells.
	      checkhash
		      If  set,	bash  checks  that a command found in the hash table exists before trying to
		      execute it.  If a hashed command no longer exists, a normal path search is  performed.
	      checkwinsize
		      If  set, bash checks the window size after each command and, if necessary, updates the
		      values of LINES and COLUMNS.
	      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 cannot 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 interactive shells.
	      extglob If  set,	the extended pattern matching features described above under Pathname Expan�
		      sion are enabled.
	      histappend
		      If set, the history list is appended to the file named by the value  of  the  HISTFILE
		      variable when the shell exits, rather than overwriting the file.
	      histreedit
		      If  set,	and  readline  is  being  used, a user is given the opportunity to re-edit a
		      failed history substitution.
	      histverify
		      If set, and readline is being used, the results of history substitution are not  imme�
		      diately  passed  to  the shell parser.  Instead, the resulting line is loaded into the
		      readline editing buffer, allowing further modification.
	      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 interactive login shell exits.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word and all remaining  characters
		      on  that line to be ignored in an interactive shell (see COMMENTS above).	 This option
		      is enabled by default.
	      lithist If set, and the cmdhist option is enabled, multi-line commands are saved to  the	his�
		      tory with embedded newlines rather than using semicolon separators where possible.
	      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  displayed.
	      no_empty_cmd_completion
		      If  set, and readline is being used, bash will not attempt to search the PATH for pos�
		      sible 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 Programmable 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 restricted mode (see  RESTRICTED  SHELL
		      below).	The  value may not be changed.	This is not reset when the startup files are
		      executed, allowing the startup files to discover 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 parameters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to find the directory containing
		      the file supplied as an argument.	 This option is enabled by default.
	      xpg_echo
		      If set, the echo builtin expands backslash-escape sequences by default.
       suspend [-f]
	      Suspend  the  execution  of this shell until it receives a SIGCONT signal.  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	pri�
	      maries 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 oper�
		     ators.
	      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 argu�
	      ments.

	      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 argument 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 evaluated
		     according to precedence using the rules listed above.
	      5 or more arguments
		     The expression is parsed and evaluated according to precedence using the  rules  listed
		     above.

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

       trap [-lp] [arg] [sigspec ...]
	      The command arg is to be read and executed when the shell receives signal(s) sigspec.  If	 arg
	      is  absent 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 signal specified by  each  sigspec
	      is ignored by the shell and by the commands it invokes.  If arg is not present and -p has been
	      supplied, then the trap commands associated with each sigspec are displayed.  If no  arguments
	      are  supplied  or	 if  only -p is given, trap prints the list of commands associated with each
	      signal number.  Each sigspec is either a signal name defined in <signal.h>, or a	signal	num�
	      ber.   If	 a  sigspec  is	 EXIT  (0) the command arg is executed on exit from the shell.	If a
	      sigspec is DEBUG, the command arg is executed after every simple command	(see  SHELL  GRAMMAR
	      above).	The -l option causes the shell to print a list of signal names and their correspond�
	      ing numbers.  Signals ignored upon entry 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 [-atp] 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,  respec�
	      tively.	If  the	 name  is not found, then nothing is printed, and an exit status of false is
	      returned.	 If the -p option is used, type either returns the name of the disk file that  would
	      be executed if name were specified as a command name, or nothing if ``type -t name'' would not
	      return file.  If a command is hashed, -p prints 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 con�
	      tain an executable named name.  This includes aliases and functions, if and  only	 if  the  -p
	      option  is  not also used.  The table of hashed commands is not consulted when using -a.	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 value of limit can be a number in the unit specified for
	      the resource, or the value unlimited.  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.  If limit is omitted, the current value of the soft
	      limit of the resource is printed, unless the -H option is given.	When more than one  resource
	      is  specified, the limit name and unit are printed before the value.  Other options are inter�
	      preted as follows:
	      -a     All current limits are reported
	      -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 is encountered,  a	non-
	      numeric argument other than unlimited is supplied as limit, 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 symbolic form; the default output is an octal number.  If the
	      -p option is supplied, and mode is omitted, the output is in a form  that	 may  be  reused  as
	      input.  The return status is 0 if the mode was successfully changed or if no mode argument was
	      supplied, and false otherwise.

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

       unset [-fv] [name ...]
	      For  each name, remove the corresponding variable or function.  If no options are supplied, or
	      the -v option is given, each name refers to a shell variable.  Read-only variables may not  be
	      unset.   If  -f is 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  subse�
	      quent commands.  If any of RANDOM, SECONDS, LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are
	      unset, they lose their special properties, even if they are subsequently reset.  The exit sta�
	      tus is true unless a name does not exist or is readonly.

       wait [n]
	      Wait  for the specified process and return its termination status.  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.	Oth�
	      erwise, 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:

       �      changing directories with cd

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

       �      specifying command names containing /

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

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

       �      importing function definitions from the shell environment at startup

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

       �      redirecting output using the >, >|, <>, >&, &>, and >> redirection operators

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

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

       �      specifying the -p option to the command builtin command

       �      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 COMMAND 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 Utilities, 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 pro�
       cess 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-2.05		    2001 Mar 5			  BASH(1)
