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BASH(1) 							       BASH(1)



NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2005 by the Free Software Foundation, Inc.

DESCRIPTION
       Bash  is  an  sh-compatible  command language interpreter that executes
       commands read from the standard input or from a file.  Bash also incor
       porates useful features from the Korn and C shells (ksh and csh).

       Bash  is  intended  to be a conformant implementation of the IEEE POSIX
       Shell and Tools specification (IEEE Working Group 1003.2).  Bash can be
       configured to be POSIX-conformant by default.

OPTIONS
       In  addition  to  the  single-character shell options documented in the
       description of the set builtin command, bash interprets	the  following
       options when it is invoked:

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

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

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

       --login
	      Equivalent to -l.

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

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

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

       --posix
	      Change the behavior of bash where the default operation  differs
	      from  the  POSIX	1003.2	standard  to match the standard (posix
	      mode).

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

       --verbose
	      Equivalent to  -v.

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

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

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

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

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

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

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

       When  an  interactive  shell that is not a login shell is started, bash
       reads and executes commands from  /etc/bash.bashrc  and	~/.bashrc,  if
       these  files  exist.  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 /etc/bash.bashrc and ~/.bashrc.

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

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

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

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

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

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

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

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

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

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

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

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

       The standard output of command is connected via a pipe to the  standard
       input  of  command2.   This connection is performed before any redirec
       tions specified by the command (see REDIRECTION below).

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

       If  the	time reserved word precedes a pipeline, the elapsed as well as
       user and system time consumed by its execution are  reported  when  the
       pipeline  terminates.   The -p option changes the output format to that
       specified by POSIX.  The TIMEFORMAT variable may be  set  to  a	format
       string  that  specifies how the timing information should be displayed;
       see the description of TIMEFORMAT under Shell Variables below.

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

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

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

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

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

       The control operators && and  denote AND lists and OR lists,  respec
       tively.	An AND list has the form

	      command1 && command2

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

       An OR list has the form

	      command1	command2


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

   Compound Commands
       A compound command is one of the following:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       Words of the form $string are treated specially.  The word expands to
       string, with backslash-escaped characters replaced as specified by  the
       ANSI  C	standard.  Backslash escape sequences, if present, are decoded
       as follows:
	      \a     alert (bell)
	      \b     backspace
	      \e     an escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal tab
	      \v     vertical tab
	      \\     backslash
	      \     single quote
	      \nnn   the eight-bit character whose value is  the  octal  value
		     nnn (one to three digits)
	      \xHH   the  eight-bit  character	whose value is the hexadecimal
		     value HH (one or two hex digits)
	      \cx    a control-x character

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

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

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

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

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

	      name=[value]

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

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

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

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

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

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands  to  the	full file name used to invoke this instance of
	      bash.
       BASH_ARGC
	      An array variable whose values are the number of	parameters  in
	      each frame of the current bash execution call stack.  The number
	      of parameters to	the  current  subroutine  (shell  function  or
	      script  executed	with  . or source) is at the top of the stack.
	      When a subroutine is executed, the number of  parameters	passed
	      is pushed onto BASH_ARGC.  The shell sets BASH_ARGC only when in
	      extended debugging mode (see the	description  of  the  extdebug
	      option to the shopt builtin below)
       BASH_ARGV
	      An  array  variable containing all of the parameters in the cur
	      rent bash execution call stack.  The final parameter of the last
	      subroutine  call is at the top of the stack; the first parameter
	      of the initial call is at the bottom.  When a subroutine is exe
	      cuted,  the  parameters supplied are pushed onto BASH_ARGV.  The
	      shell sets BASH_ARGV only when in extended debugging  mode  (see
	      the  description	of  the  extdebug  option to the shopt builtin
	      below)
       BASH_COMMAND
	      The command currently being executed or about  to  be  executed,
	      unless the shell is executing a command as the result of a trap,
	      in which case it is the command executing at  the  time  of  the
	      trap.
       BASH_EXECUTION_STRING
	      The command argument to the -c invocation option.
       BASH_LINENO
	      An  array  variable whose members are the line numbers in source
	      files   corresponding    to    each    member    of    FUNCNAME.
	      ${BASH_LINENO[$i]}  is  the line number in the source file where
	      ${FUNCNAME[$ifP]} was called.   The  corresponding  source  file
	      name  is	${BASH_SOURCE[$i]}.   Use LINENO to obtain the current
	      line number.
       BASH_REMATCH
	      An array variable whose members are assigned by  the  =~	binary
	      operator	to the [[ conditional command.	The element with index
	      0 is the portion of  the	string	matching  the  entire  regular
	      expression.   The  element  with	index  n is the portion of the
	      string matching the nth parenthesized subexpression.  This vari
	      able is read-only.
       BASH_SOURCE
	      An  array variable whose members are the source filenames corre
	      sponding to the elements in the FUNCNAME array variable.
       BASH_SUBSHELL
	      Incremented by one each time a subshell or subshell  environment
	      is spawned.  The initial value is 0.
       BASH_VERSINFO
	      A readonly array variable whose members hold version information
	      for this instance of bash.  The values  assigned	to  the  array
	      members are as follows:
	      BASH_VERSINFO[0]	      The  major version number (the release).
	      BASH_VERSINFO[1]	      The minor version number (the  version).
	      BASH_VERSINFO[2]	      The patch level.
	      BASH_VERSINFO[3]	      The build version.
	      BASH_VERSINFO[4]	      The release status (e.g., beta1).
	      BASH_VERSINFO[5]	      The value of MACHTYPE.

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

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

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

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

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

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

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

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

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

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

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

       HOSTNAME
	      Automatically set to the name of the current host.

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

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

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

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

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

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

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

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

       PPID   The process ID of the shells parent.  This  variable  is	read
	      only.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       auto_resume
	      This variable controls how the shell interacts with the user and
	      job control.  If	this  variable	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 analo
	      gous to the %?  job identifier (see JOB CONTROL below).  If  set
	      to  any  other  value, the supplied string must be a prefix of a
	      stopped jobs name; this provides functionality analogous to the
	      %string job identifier.

       command_not_found_handle
	      The name of a shell function to be called if a command cannot be
	      found. The return value of this function should  be  0,  if  the
	      command  is available after execution of the function, otherwise
	      127 (EX_NOTFOUND).  Enabled only in interactive, non POSIX  mode
	      shells. This is a Debian extension.

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

   Arrays
       Bash  provides  one-dimensional	array  variables.  Any variable may be
       used as an array; the declare builtin will explicitly declare an array.
       There  is no maximum limit on the size of an array, nor any requirement
       that members be indexed or assigned contiguously.  Arrays  are  indexed
       using integers and are zero-based.

       An  array is created automatically if any variable is assigned to using
       the syntax name[subscript]=value.   The	subscript  is  treated	as  an
       arithmetic  expression  that  must evaluate to a number greater than or
       equal to zero.  To explicitly declare an array,	use  declare  -a  name
       (see SHELL BUILTIN COMMANDS below).  declare -a name[subscript] is also
       accepted; the subscript is ignored.  Attributes may be specified for an
       array variable using the declare and readonly builtins.	Each attribute
       applies to all members of an array.

       Arrays  are  assigned  to  using  compound  assignments	of  the   form
       name=(value1  ...  valuen),  where  each  value	is  of	the form [sub
       script]=string.	Only string is required.  If the optional brackets and
       subscript  are supplied, that index is assigned to; otherwise the index
       of the element assigned is the last index assigned to by the  statement
       plus  one.   Indexing  starts at zero.  This syntax is also accepted by
       the declare builtin.  Individual array  elements  may  be  assigned  to
       using the name[subscript]=value syntax introduced above.

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

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

       The  declare,  local,  and readonly builtins each accept a -a option to
       specify an array.  The read builtin accepts a -a  option  to  assign  a
       list  of  words	read from the standard input to an array.  The set and
       declare builtins display array values in a way that allows them	to  be
       reused as assignments.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       In each of the cases below, word is subject to tilde expansion, parame
       ter expansion, command substitution, and  arithmetic  expansion.   When
       not  performing substring expansion, bash tests for a parameter that is
       unset or null; omitting the colon results in a test only for a  parame
       ter that is unset.

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

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

       ${!name[@]}
       ${!name[*]}
	      If  name	is  an	array  variable,  expands to the list of array
	      indices (keys) assigned in name.	 If  name  is  not  an	array,
	      expands  to 0 if name is set and null otherwise.	When @ is used
	      and the expansion appears within double quotes, each key expands
	      to a separate word.

       ${#parameter}
	      The  length  in  characters of the value of parameter is substi
	      tuted.  If parameter is * or @, the  value  substituted  is  the
	      number  of positional parameters.  If parameter is an array name
	      subscripted by * or @, the value substituted is  the  number  of
	      elements in the array.

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

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

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

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


	      $(command)
       or
	      command

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

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

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

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

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

	      $((expression))

       The old format $[expression] is	deprecated  and  will  be  removed  in
       upcoming versions of bash.

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

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

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

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

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

       The shell treats each character of IFS as a delimiter, and  splits  the
       results of the other expansions into words on these characters.	If IFS
       is unset, or its value is exactly ,  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
       delimiter.  If the value of IFS is null, no word splitting occurs.

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

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

   Pathname Expansion
       After  word  splitting,	unless	the -f option has been set, bash scans
       each word for the characters *, ?, and [.  If one of  these  characters
       appears,  then  the word is regarded as a pattern, and replaced with an
       alphabetically sorted list of file names matching the pattern.	If  no
       matching  file  names  are found, and the shell option nullglob is dis
       abled, the word is left unchanged.  If the nullglob option is set,  and
       no  matches  are  found,  the  word  is removed.  If the failglob shell
       option is set, and no matches are found, an error  message  is  printed
       and  the  command  is  not executed.  If the shell option nocaseglob is
       enabled, the match is performed without regard to the  case  of	alpha
       betic  characters.   Note  that when using range expressions like [a-z]
       (see below), letters of the other case may be  included,  depending  on
       the  setting of LC_COLLATE.  When a pattern is used for pathname expan
       sion, the character .  at the start of a name or  immediately  fol
       lowing a slash must be matched explicitly, unless the shell option dot
       glob is set.  When matching a pathname, the slash character must always
       be  matched  explicitly.   In  other cases, the .  character is not
       treated specially.  See the description	of  shopt  below  under  SHELL
       BUILTIN	COMMANDS  for a description of the nocaseglob, nullglob, fail
       glob, and dotglob shell options.

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

       Pattern Matching

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

       The special pattern characters have the following meanings:

       *      Matches any string, including the null string.
       ?      Matches any single character.
       [...]  Matches  any  one of the enclosed characters.  A pair of charac
	      ters separated by a hyphen denotes a range expression; any char
	      acter  that sorts between those two characters, inclusive, using
	      the current locales collating sequence and  character  set,  is
	      matched.	 If the first character following the [ is a !	or a ^
	      then any character not enclosed is matched.  The	sorting  order
	      of  characters in range expressions is determined by the current
	      locale and the value of the LC_COLLATE shell variable,  if  set.
	      A  - may be matched by including it as the first or last charac
	      ter in the set.  A ] may be matched by including it as the first
	      character in the set.

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

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

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

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

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

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

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

       In  the	following descriptions, if the file descriptor number is omit
       ted, and the first character of the  redirection  operator  is  <,  the
       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 descrip
       tions, unless otherwise noted, is subjected to brace  expansion,  tilde
       expansion, parameter expansion, command substitution, arithmetic expan
       sion, quote removal, pathname expansion, and  word  splitting.	If  it
       expands to more than one word, bash reports an error.

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 > dirlist

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

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

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

       NOTE: Bash, as packaged for Debian, does not support using the /dev/tcp
       and /dev/udp files.

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

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

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

       The general format for redirecting input is:

	      [n]word

       If the redirection operator is >, and the noclobber option to  the  set
       builtin	has  been enabled, the redirection will fail if the file whose
       name results from the expansion of word exists and is a	regular  file.
       If the redirection operator is >|, or the redirection operator is > and
       the noclobber option to the set builtin command	is  not  enabled,  the
       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  stan
       dard  error  output  (file  descriptor  2) to be redirected to the file
       whose name is the expansion of word with this construct.

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

	      &>word
       and
	      >&word

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

	      >word 2>&1

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

       The format of here-documents is:

	      <<[-]word
		      here-document
	      delimiter

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

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

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

	      <<&word

       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.

   Moving File Descriptors
       The redirection operator

	      [n]<&digit-

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

       Similarly, the redirection operator

	      [n]>&digit-

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

   Opening File Descriptors for Reading and Writing
       The redirection operator

	      [n]<>word

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

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

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

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

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

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

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

FUNCTIONS
       A  shell  function,  defined  as  described  above under SHELL GRAMMAR,
       stores a series of commands for later execution.  When the  name  of  a
       shell  function	is used as a simple command name, the list of commands
       associated with that function name is executed.	Functions are executed
       in  the	context  of  the  current  shell; no new process is created to
       interpret them (contrast this with the execution of  a  shell  script).
       When  a	function is executed, the arguments to the function become the
       positional parameters during its execution.  The special parameter # is
       updated	to reflect the change.	Special parameter 0 is unchanged.  The
       first element of the FUNCNAME variable is set to the name of the  func
       tion  while  the function is executing.	All other aspects of the shell
       execution environment are identical between a function and  its	caller
       with the exception that the DEBUG and RETURN traps (see the description
       of the trap builtin under SHELL BUILTIN COMMANDS below) are not	inher
       ited  unless  the  function has been given the trace attribute (see the
       description of the declare builtin below) or  the  -o  functrace  shell
       option  has  been enabled with the set builtin (in which case all func
       tions inherit the DEBUG and RETURN traps).

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

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

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

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

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

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

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

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

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

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

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

       See  the description of the test builtin command (section SHELL BUILTIN
       COMMANDS below) for the handling of parameters (i.e.   missing  parame
       ters).

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

       string1 == string2
	      True if the strings are equal.  = may be used in place of == for
	      strict POSIX compliance.

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

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

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

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

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

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

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

       3.     Redirections are performed as described above under REDIRECTION.

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

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

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

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

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

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

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

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

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

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

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


	     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 invocation

	     the  file	creation  mode mask as set by umask or inherited from
	      the shells parent

	     current traps set by trap

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

	     shell  functions  defined during execution or inherited from the
	      shells parent in the environment

	     options enabled at invocation (either by default  or  with  com
	      mand-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 con
       sists of the following.	Unless otherwise noted, the values are	inher
       ited from the shell.


	     the  shells  open	files,	plus any modifications and additions
	      specified by redirections to the command

	     the current working directory

	     the file creation mode mask

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

	     traps caught by the shell are reset to the values inherited from
	      the shells parent, and traps ignored by the shell are ignored

       A command invoked  in  this  separate  environment  cannot  affect  the
       shells execution environment.

       Command	substitution,  commands  grouped  with	parentheses, and asyn
       chronous commands are invoked in  a  subshell  environment  that  is  a
       duplicate  of  the  shell  environment, except that traps caught by the
       shell are reset to the values that the shell inherited from its	parent
       at invocation.  Builtin commands that are invoked as part of a pipeline
       are also executed in a subshell environment.  Changes made to the  sub
       shell environment cannot affect the shells execution environment.

       If  a  command  is  followed  by a & and job control is not active, the
       default standard input for the command is  the  empty  file  /dev/null.
       Otherwise,  the	invoked  command  inherits the file descriptors of the
       calling shell as modified by redirections.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      [1] 25647

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

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

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

       There are a number of ways to refer to a job in the shell.  The charac
       ter % introduces a job name.  Job number n may be referred to as %n.  A
       job  may  also  be referred to using a prefix of the name used to start
       it, or using a substring that appears in its command line.   For  exam
       ple, %ce refers to a stopped ce job.  If a prefix matches more than one
       job, bash reports an error.  Using %?ce, on the other hand,  refers  to
       any job containing the string ce in its command line.  If the substring
       matches more than one job, bash reports an error.  The symbols  %%  and
       %+  refer  to  the shells notion of the current job, which is the last
       job stopped while it was in the foreground  or  started	in  the  back
       ground.	 The  previous job may be referenced using %-.	In output per
       taining to jobs (e.g., the output of the jobs command), the current job
       is  always flagged with a +, and the previous job with a -.  A single %
       (with no accompanying job specification) also  refers  to  the  current
       job.

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

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

       If  an  attempt	to exit bash is made while jobs are stopped, the shell
       prints a warning message.  The jobs command may then be used to inspect
       their status.  If a second attempt to exit is made without an interven
       ing command, the shell does not print another warning, and the  stopped
       jobs are terminated.

PROMPTING
       When executing interactively, bash displays the primary prompt PS1 when
       it is ready to read a command, and the secondary  prompt  PS2  when  it
       needs  more  input  to  complete  a  command.  Bash allows these prompt
       strings to be customized by inserting  a  number  of  backslash-escaped
       special characters that are decoded as follows:
	      \a     an ASCII bell character (07)
	      \d     the  date	in "Weekday Month Date" format (e.g., "Tue May
		     26")
	      \D{format}
		     the format is passed to strftime(3)  and  the  result  is
		     inserted  into the prompt string; an empty format results
		     in a locale-specific time representation.	The braces are
		     required
	      \e     an ASCII escape character (033)
	      \h     the hostname up to the first .
	      \H     the hostname
	      \j     the number of jobs currently managed by the shell
	      \l     the basename of the shells terminal device name
	      \n     newline
	      \r     carriage return
	      \s     the  name	of  the shell, the basename of $0 (the portion
		     following the final slash)
	      \t     the current time in 24-hour HH:MM:SS format
	      \T     the current time in 12-hour HH:MM:SS format
	      \@     the current time in 12-hour am/pm format
	      \A     the current time in 24-hour HH:MM format
	      \u     the username of the current user
	      \v     the version of bash (e.g., 2.00)
	      \V     the release of bash, version + patch level (e.g., 2.00.0)
	      \w     the  current  working  directory,	with $HOME abbreviated
		     with a tilde
	      \W     the basename of the current working directory, with $HOME
		     abbreviated with a tilde
	      \!     the history number of this command
	      \#     the command number of this command
	      \$     if the effective UID is 0, a #, otherwise a $
	      \nnn   the character corresponding to the octal number nnn
	      \\     a backslash
	      \[     begin  a sequence of non-printing characters, which could
		     be used to embed a terminal  control  sequence  into  the
		     prompt
	      \]     end a sequence of non-printing characters

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

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

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

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

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

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

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

       For example, placing

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      set variable-name value

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

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

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

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

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

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

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

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

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

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

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

	      $include	/etc/inputrc

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

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

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

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

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

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

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

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

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

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

   Numeric Arguments
       digit-argument (M-0, M-1, ..., M--)
	      Add this digit to the argument already accumulating, or start  a
	      new argument.  M-- starts a negative argument.
       universal-argument
	      This  is another way to specify an argument.  If this command is
	      followed by one or more digits, optionally with a leading  minus
	      sign,  those digits define the argument.	If the command is fol
	      lowed by digits, executing  universal-argument  again  ends  the
	      numeric  argument, but is otherwise ignored.  As a special case,
	      if this command is immediately followed by a character  that  is
	      neither  a  digit or minus sign, the argument count for the next
	      command is multiplied by four.  The argument count is  initially
	      one,  so	executing this function the first time makes the argu
	      ment count four, a second time makes the argument count sixteen,
	      and so on.

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

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

   Miscellaneous
       re-read-init-file (C-x C-r)
	      Read  in	the  contents of the inputrc file, and incorporate any
	      bindings or variable assignments found there.
       abort (C-g)
	      Abort the current editing command and ring the  terminals  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-)
	      Set  the	mark to the point.  If a numeric argument is supplied,
	      the mark is set to that position.
       exchange-point-and-mark (C-x C-x)
	      Swap the point with the mark.  The current  cursor  position  is
	      set  to the saved position, and the old cursor position is saved
	      as the mark.
       character-search (C-])
	      A character is read and point is moved to the next occurrence of
	      that  character.	 A negative count searches for previous occur
	      rences.
       character-search-backward (M-C-])
	      A character is read and point is moved to  the  previous	occur
	      rence  of  that character.  A negative count searches for subse
	      quent occurrences.
       insert-comment (M-#)
	      Without a numeric argument,  the	value  of  the	readline  com
	      ment-begin  variable is inserted at the beginning of the current
	      line.  If a numeric argument is supplied, this command acts as a
	      toggle:	if  the characters at the beginning of the line do not
	      match the value of comment-begin, the value is inserted,	other
	      wise the characters in comment-begin are deleted from the begin
	      ning of the line.  In either case, the line is accepted as if  a
	      newline  had  been  typed.   The	default value of comment-begin
	      causes this command to make the current line  a  shell  comment.
	      If  a  numeric  argument	causes	the  comment  character  to be
	      removed, the line will be executed by the shell.
       glob-complete-word (M-g)
	      The word before point is	treated  as  a	pattern  for  pathname
	      expansion,  with	an asterisk implicitly appended.  This pattern
	      is used to generate a list of matching file names  for  possible
	      completions.
       glob-expand-word (C-x *)
	      The  word  before  point	is  treated  as a pattern for pathname
	      expansion, and the list of  matching  file  names  is  inserted,
	      replacing  the  word.   If  a  numeric  argument is supplied, an
	      asterisk is appended before pathname expansion.
       glob-list-expansions (C-x g)
	      The list	of  expansions	that  would  have  been  generated  by
	      glob-expand-word	is  displayed,	and the line is redrawn.  If a
	      numeric argument is supplied, an	asterisk  is  appended	before
	      pathname expansion.
       dump-functions
	      Print  all  of the functions and their key bindings to the read
	      line output stream.  If a numeric argument is supplied, the out
	      put  is  formatted  in such a way that it can be made part of an
	      inputrc file.
       dump-variables
	      Print all of the settable readline variables and their values to
	      the  readline output stream.  If a numeric argument is supplied,
	      the output is formatted in such a way that it can be  made  part
	      of an inputrc file.
       dump-macros
	      Print  all of the readline key sequences bound to macros and the
	      strings they output.  If a numeric  argument  is	supplied,  the
	      output is formatted in such a way that it can be made part of an
	      inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about the current instance of  bash.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       On startup, the history is initialized from the file named by the vari
       able  HISTFILE  (default ~/.bash_history).  The file named by the value
       of HISTFILE is truncated, if necessary, to contain  no  more  than  the
       number of lines specified by the value of HISTFILESIZE.	When an inter
       active shell exits, the last $HISTSIZE lines are copied from  the  his
       tory list to $HISTFILE.	If the histappend shell option is enabled (see
       the description of shopt under SHELL BUILTIN COMMANDS below), the lines
       are  appended  to the history file, otherwise the history file is over
       written.  If HISTFILE is unset, or if the history file  is  unwritable,
       the  history  is not saved.  After saving the history, the history file
       is truncated to contain no more than HISTFILESIZE lines.  If  HISTFILE
       SIZE is not set, no truncation is performed.

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

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

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

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

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

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

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

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

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

       !      Start  a	history substitution, except when followed by a blank,
	      newline, carriage return, = or ( (when the extglob shell	option
	      is enabled using the shopt builtin).
       !n     Refer to command line n.
       !-n    Refer to the current command line minus n.
       !!     Refer to the previous command.  This is a synonym for !-1.
       !string
	      Refer to the most recent command starting with string.
       !?string[?]
	      Refer  to the most recent command containing string.  The trail
	      ing ? may be omitted if string is followed immediately by a new
	      line.
       ^string1^string2^
	      Quick  substitution.  Repeat the last command, replacing string1
	      with string2.  Equivalent to !!:s/string1/string2/ (see Mod
	      ifiers below).
       !#     The entire command line typed so far.

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

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

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

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

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

SHELL BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by - accepts -- to signify the end of the
       options.  For example, the :, true, false, and  test  builtins  do  not
       accept options.
       : [arguments]
	      No  effect;  the command does nothing beyond expanding arguments
	      and performing any specified redirections.  A zero exit code  is
	      returned.

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

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

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

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

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

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

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

       cd [-L|-P] [dir]
	      Change the current directory to dir.  The variable HOME  is  the
	      default  dir.   The  variable CDPATH defines the search path for
	      the directory containing dir.  Alternative  directory  names  in
	      CDPATH  are  separated by a colon (:).  A null directory name in
	      CDPATH is the same as the current directory,  i.e.,  ..	If
	      dir  begins  with  a  slash (/), then CDPATH is not used. The -P
	      option says to use the physical directory structure  instead  of
	      following  symbolic  links  (see	also  the -P option to the set
	      builtin command); the -L option forces symbolic links to be fol
	      lowed.   An  argument  of - is equivalent to $OLDPWD.  If a non-
	      empty directory name from CDPATH is used, or if - is  the  first
	      argument,  and  the directory change is successful, the absolute
	      pathname of the new working directory is written to the standard
	      output.	The return value is true if the directory was success
	      fully changed; false otherwise.

       caller [expr]
	      Returns the context of any active subroutine call (a shell func
	      tion  or a script executed with the . or source builtins.  With
	      out expr, caller displays the line number and source filename of
	      the  current subroutine call.  If a non-negative integer is sup
	      plied as expr, caller displays the line number, subroutine name,
	      and  source  file  corresponding to that position in the current
	      execution call stack.  This extra information may be  used,  for
	      example,	to print a stack trace.  The current frame is frame 0.
	      The return value is 0 unless the shell is not executing  a  sub
	      routine  call or expr does not correspond to a valid position in
	      the call stack.

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

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

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

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

       complete  [-abcdefgjksuv] [-o comp-option] [-A action] [-G globpat] [-W
       wordlist] [-P prefix] [-S suffix]
	      [-X filterpat] [-F function] [-C command] name [name ...]
       complete -pr [name ...]
	      Specify  how arguments to each name should be completed.	If the
	      -p option is supplied, or if no options are  supplied,  existing
	      completion  specifications are printed in a way that allows them
	      to be reused as input.  The -r option removes a completion spec
	      ification  for each name, or, if no names are supplied, all com
	      pletion specifications.

	      The process of applying  these  completion  specifications  when
	      word  completion	is  attempted  is  described  above under Pro
	      grammable Completion.

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

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

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

       declare [-afFirtx] [-p] [name[=value] ...]
       typeset [-afFirtx] [-p] [name[=value] ...]
	      Declare variables and/or give them attributes.  If no names  are
	      given  then display the values of variables.  The -p option will
	      display the attributes and values of  each  name.   When	-p  is
	      used,  additional  options  are ignored.	The -F option inhibits
	      the display of function definitions; only the function name  and
	      attributes are printed.  If the extdebug shell option is enabled
	      using shopt, the source file name  and  line  number  where  the
	      function	is  defined  are  displayed  as  well.	 The -F option
	      implies -f.  The following options can be used to restrict  out
	      put  to  variables with the specified attribute or to give vari
	      ables attributes:
	      -a     Each name is an array variable (see Arrays above).
	      -f     Use function names only.
	      -i     The variable is treated as an integer; arithmetic evalua
		     tion  (see  ARITHMETIC EVALUATION ) is performed when the
		     variable is assigned a value.
	      -r     Make names readonly.  These names cannot then be assigned
		     values by subsequent assignment statements or unset.
	      -t     Give  each  name  the  trace attribute.  Traced functions
		     inherit the DEBUG	and  RETURN  traps  from  the  calling
		     shell.   The  trace  attribute has no special meaning for
		     variables.
	      -x     Mark names for export  to	subsequent  commands  via  the
		     environment.

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

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

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

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

       echo [-neE] [arg ...]
	      Output the args, separated by spaces,  followed  by  a  newline.
	      The return status is always 0.  If -n is specified, the trailing
	      newline is suppressed.  If the -e option is  given,  interpreta
	      tion  of	the following backslash-escaped characters is enabled.
	      The -E option disables the interpretation of these escape  char
	      acters,  even  on systems where they are interpreted by default.
	      The xpg_echo shell option may be used to	dynamically  determine
	      whether  or not echo expands these escape characters by default.
	      echo does not interpret -- to mean the  end  of  options.   echo
	      interprets the following escape sequences:
	      \a     alert (bell)
	      \b     backspace
	      \c     suppress trailing newline
	      \e     an escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal tab
	      \v     vertical tab
	      \\     backslash
	      \0nnn  the  eight-bit  character	whose value is the octal value
		     nnn (zero to three octal digits)
	      \nnn   the eight-bit character whose value is  the  octal  value
		     nnn (one to three octal digits)
	      \xHH   the  eight-bit  character	whose value is the hexadecimal
		     value HH (one or two hex digits)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	      If the HISTTIMEFORMAT is set, the time stamp information associ
	      ated with each history entry is written  to  the	history  file.
	      The  return  value is 0 unless an invalid option is encountered,
	      an error occurs while reading or writing the  history  file,  an
	      invalid  offset is supplied as an argument to -d, or the history
	      expansion supplied as an argument to -p fails.

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

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

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

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

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

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

       logout Exit a login shell.

       popd [-n] [+n] [-n]
	      Removes  entries	from  the directory stack.  With no arguments,
	      removes the top directory from the stack, and performs a	cd  to
	      the new top directory.  Arguments, if supplied, have the follow
	      ing meanings:
	      +n     Removes the nth entry counting from the left of the  list
		     shown  by	dirs, starting with zero.  For example: popd
		     +0 removes the first directory, popd +1 the second.
	      -n     Removes the nth entry counting from the right of the list
		     shown by dirs, starting with zero.  For  example:	popd
		     -0  removes the last directory, popd -1 the next to
		     last.
	      -n     Suppresses the normal change of directory	when  removing
		     directories  from	the  stack,  so that only the stack is
		     manipulated.

	      If the popd command is successful, a dirs is performed as  well,
	      and  the	return	status is 0.  popd returns false if an invalid
	      option is encountered, the directory stack is empty, a non-exis
	      tent directory stack entry is specified, or the directory change
	      fails.

       printf [-v var] format [arguments]
	      Write the formatted arguments to the standard output  under  the
	      control  of  the format.	The format is a character string which
	      contains three types of objects:	plain  characters,  which  are
	      simply  copied  to  standard output, character escape sequences,
	      which are converted and copied to the standard output, and  for
	      mat  specifications,  each  of which causes printing of the next
	      successive argument.  In addition to the standard printf(1) for
	      mats,  %b  causes printf to expand backslash escape sequences in
	      the corresponding argument (except that  \c  terminates  output,
	      backslashes in \, \", and \? are not removed, and octal escapes
	      beginning with \0 may contain up to four digits), and %q	causes
	      printf to output the corresponding argument in a format that can
	      be reused as shell input.

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

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

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

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

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

       read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d
       delim] [name ...]
	      One  line  is  read  from  the  standard input, or from the file
	      descriptor fd supplied as an argument to the -u option, and  the
	      first word is assigned to the first name, the second word to the
	      second name, and so on, with leftover words and their  interven
	      ing  separators  assigned  to the last name.  If there are fewer
	      words read from the input stream than names, the remaining names
	      are  assigned  empty  values.  The characters in IFS are used to
	      split the line into words.  The backslash character (\)  may  be
	      used  to	remove any special meaning for the next character read
	      and for line continuation.  Options, if supplied, have the  fol
	      lowing meanings:
	      -a aname
		     The words are assigned to sequential indices of the array
		     variable aname, starting at 0.  aname is unset before any
		     new  values  are  assigned.   Other  name	arguments  are
		     ignored.
	      -d delim
		     The first character of delim is  used  to	terminate  the
		     input line, rather than newline.
	      -e     If the standard input is coming from a terminal, readline
		     (see READLINE above) is used to obtain the line.
	      -n nchars
		     read returns after reading nchars characters rather  than
		     waiting for a complete line of input.
	      -p prompt
		     Display prompt on standard error, without a trailing new
		     line, before attempting to read any input.  The prompt is
		     displayed only if input is coming from a terminal.
	      -r     Backslash does not act as an escape character.  The back
		     slash is considered to be part of the line.  In  particu
		     lar,  a  backslash-newline pair may not be used as a line
		     continuation.
	      -s     Silent mode.  If input is coming from a terminal, charac
		     ters are not echoed.
	      -t timeout
		     Cause  read  to time out and return failure if a complete
		     line of input is not read within timeout  seconds.   This
		     option  has  no  effect if read is not reading input from
		     the terminal or a pipe.
	      -u fd  Read input from file descriptor fd.

	      If no names are supplied, the line read is assigned to the vari
	      able  REPLY.   The  return  code	is zero, unless end-of-file is
	      encountered, read times out, or an invalid  file	descriptor  is
	      supplied as the argument to -u.

       readonly [-apf] [name[=word] ...]
	      The  given  names are marked readonly; the values of these names
	      may not be changed by subsequent assignment.  If the  -f	option
	      is  supplied,  the  functions  corresponding to the names are so
	      marked.  The -a option restricts the variables to arrays.  If no
	      name  arguments  are  given,  or if the -p option is supplied, a
	      list of all readonly names is printed.   The  -p	option	causes
	      output  to be displayed in a format that may be reused as input.
	      If a variable name is followed by =word, the value of the  vari
	      able  is	set to word.  The return status is 0 unless an invalid
	      option is encountered, one of the names is  not  a  valid  shell
	      variable name, or -f is supplied with a name that is not a func
	      tion.

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

       set [--abefhkmnptuvxBCHP] [-o option] [arg ...]
	      Without options, the name and value of each shell  variable  are
	      displayed in a format that can be reused as input for setting or
	      resetting the currently-set variables.  Read-only variables can
	      not  be  reset.  In posix mode, only shell variables are listed.
	      The output is sorted according  to  the  current	locale.   When
	      options  are specified, they set or unset shell attributes.  Any
	      arguments remaining after the options are processed are  treated
	      as  values  for  the  positional parameters and are assigned, in
	      order, to $1, $2, ...  $n.  Options, if specified, have the fol
	      lowing meanings:
	      -a      Automatically  mark  variables  and  functions which are
		      modified or created for export  to  the  environment  of
		      subsequent commands.
	      -b      Report  the status of terminated background jobs immedi
		      ately, rather than before the next primary prompt.  This
		      is effective only when job control is enabled.
	      -e      Exit  immediately if a simple command (see SHELL GRAMMAR
		      above) exits with a non-zero status.  The shell does not
		      exit  if	the  command that fails is part of the command
		      list immediately following a  while  or  until  keyword,
		      part  of the test in an if statement, part of a && or
		      list, or if the commands return value is being inverted
		      via  !.	A  trap on ERR, if set, is executed before the
		      shell exits.
	      -f      Disable pathname expansion.
	      -h      Remember the location of commands as they are looked  up
		      for execution.  This is enabled by default.
	      -k      All  arguments  in the form of assignment statements are
		      placed in the environment for a command, not just  those
		      that precede the command name.
	      -m      Monitor  mode.   Job control is enabled.	This option is
		      on by default for interactive  shells  on  systems  that
		      support  it  (see  JOB  CONTROL above).  Background pro
		      cesses run in a separate process group and a  line  con
		      taining  their exit status is printed upon their comple
		      tion.
	      -n      Read commands but do not execute them.  This may be used
		      to  check  a  shell  script  for syntax errors.  This is
		      ignored by interactive shells.
	      -o option-name
		      The option-name can be one of the following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use an emacs-style command line  editing	inter
			      face.  This is enabled by default when the shell
			      is interactive, unless the shell is started with
			      the --noediting option.
		      errtrace
			      Same as -E.
		      functrace
			      Same as -T.
		      errexit Same as -e.
		      hashall Same as -h.
		      histexpand
			      Same as -H.
		      history Enable command history, as described above under
			      HISTORY.	This option is on by default in inter
			      active shells.
		      ignoreeof
			      The   effect   is   as   if  the	shell  command
			      IGNOREEOF=10 had been  executed  (see  Shell
			      Variables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.  nolog Currently ignored.
		      notify  Same as -b.
		      nounset Same as -u.
		      onecmd  Same as -t.
		      physical
			      Same as -P.
		      pipefail
			      If  set,	the  return value of a pipeline is the
			      value of the last (rightmost)  command  to  exit
			      with  a non-zero status, or zero if all commands
			      in the pipeline exit successfully.  This	option
			      is disabled by default.
		      posix   Change  the  behavior  of bash where the default
			      operation differs from the POSIX 1003.2 standard
			      to match the standard (posix mode).
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      vi      Use a vi-style command line editing interface.
		      xtrace  Same as -x.
		      If -o is supplied with no option-name, the values of the
		      current options are printed.  If +o is supplied with  no
		      option-name,  a  series  of set commands to recreate the
		      current option settings is  displayed  on  the  standard
		      output.
	      -p      Turn  on	privileged  mode.   In this mode, the $ENV and
		      $BASH_ENV files are not processed, shell	functions  are
		      not  inherited  from  the environment, and the SHELLOPTS
		      variable, if it appears in the environment, is  ignored.
		      If  the shell is started with the effective user (group)
		      id not equal to the real user (group)  id,  and  the  -p
		      option  is not supplied, these actions are taken and the
		      effective user id is set to the real user id.  If the -p
		      option  is supplied at startup, the effective user id is
		      not reset.  Turning this option off causes the effective
		      user  and group ids to be set to the real user and group
		      ids.
	      -t      Exit after reading and executing one command.
	      -u      Treat unset variables as an error when performing param
		      eter  expansion.	 If expansion is attempted on an unset
		      variable, the shell prints an error message, and, if not
		      interactive, exits with a non-zero status.
	      -v      Print shell input lines as they are read.
	      -x      After  expanding	each simple command, for command, case
		      command, select command, or arithmetic for command, dis
		      play  the expanded value of PS4, followed by the command
		      and its expanded arguments or associated word list.
	      -B      The shell performs brace expansion (see Brace  Expansion
		      above).  This is on by default.
	      -C      If  set,	bash  does not overwrite an existing file with
		      the >, >&, and <> redirection operators.	 This  may  be
		      overridden when creating output files by using the redi
		      rection operator >| instead of >.
	      -E      If set, any trap on ERR is inherited by shell functions,
		      command  substitutions,  and commands executed in a sub
		      shell environment.  The ERR trap is normally not	inher
		      ited in such cases.
	      -H      Enable !	style history substitution.  This option is on
		      by default when the shell is interactive.
	      -P      If set, the shell does not follow  symbolic  links  when
		      executing  commands  such  as cd that change the current
		      working  directory.   It	uses  the  physical  directory
		      structure instead.  By default, bash follows the logical
		      chain of	directories  when  performing  commands  which
		      change the current directory.
	      -T      If  set,	any traps on DEBUG and RETURN are inherited by
		      shell functions,	command  substitutions,  and  commands
		      executed	in  a  subshell  environment.	The  DEBUG and
		      RETURN traps are normally not inherited in such cases.
	      --      If no arguments follow this option, then the  positional
		      parameters are unset.  Otherwise, the positional parame
		      ters are set to the args, even if  some  of  them  begin
		      with a -.
	      -       Signal  the  end of options, cause all remaining args to
		      be assigned to the positional parameters.  The -x and -v
		      options are turned off.  If there are no args, the posi
		      tional parameters remain unchanged.

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

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

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

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

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

	      The list of shopt options is:

	      cdable_vars
		      If  set,	an  argument to the cd builtin command that is
		      not a directory is assumed to be the name of a  variable
		      whose value is the directory to change to.
	      cdspell If set, minor errors in the spelling of a directory com
		      ponent in a cd command will be  corrected.   The	errors
		      checked for are transposed characters, a missing charac
		      ter, and one character too many.	 If  a	correction  is
		      found,  the corrected file name is printed, and the com
		      mand proceeds.  This option is only used by  interactive
		      shells.
	      checkhash
		      If set, bash checks that a command found in the hash ta
		      ble exists before trying to execute  it.	 If  a	hashed
		      command  no  longer exists, a normal path search is per
		      formed.
	      checkwinsize
		      If set, bash checks the window size after  each  command
		      and,  if	necessary,  updates  the  values  of LINES and
		      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 can
		      not execute the file specified as  an  argument  to  the
		      exec  builtin  command.	An  interactive shell does not
		      exit if exec fails.
	      expand_aliases
		      If set, aliases are expanded as  described  above  under
		      ALIASES.	This option is enabled by default for interac
		      tive shells.
	      extdebug
		      If set,  behavior  intended  for	use  by  debuggers  is
		      enabled:
		      1.     The -F option to the declare builtin displays the
			     source file name and line number corresponding to
			     each function name supplied as an argument.
		      2.     If  the  command  run by the DEBUG trap returns a
			     non-zero value, the next command is  skipped  and
			     not executed.
		      3.     If  the  command  run by the DEBUG trap returns a
			     value of 2, and the shell is executing in a  sub
			     routine  (a shell function or a shell script exe
			     cuted by the . or source  builtins),  a  call  to
			     return is simulated.
		      4.     BASH_ARGC	and BASH_ARGV are updated as described
			     in their descriptions above.
		      5.     Function tracing is enabled:   command  substitu
			     tion, shell functions, and subshells invoked with
			     ( command ) inherit the DEBUG and RETURN traps.
		      6.     Error tracing is enabled:	command  substitution,
			     shell  functions,	and  subshells	invoked with (
			     command ) inherit the ERROR trap.
	      extglob If set, the extended pattern matching features described
		      above under Pathname Expansion are enabled.
	      extquote
		      If  set,	$string  and  $"string" quoting is performed
		      within  ${parameter}  expansions	enclosed   in	double
		      quotes.  This option is enabled by default.
	      failglob
		      If  set,	patterns  which fail to match filenames during
		      pathname expansion result in an expansion error.
	      force_fignore
		      If set, the suffixes  specified  by  the	FIGNORE  shell
		      variable	cause words to be ignored when performing word
		      completion even if the ignored words are the only possi
		      ble  completions.   See  SHELL  VARIABLES  above	for  a
		      description of  FIGNORE.	 This  option  is  enabled  by
		      default.
	      gnu_errfmt
		      If set, shell error messages are written in the standard
		      GNU error message format.
	      histappend
		      If set, the history list is appended to the  file  named
		      by  the  value  of  the HISTFILE variable when the shell
		      exits, rather than overwriting the file.
	      histreedit
		      If set, and readline is being used, a user is given  the
		      opportunity to re-edit a failed history substitution.
	      histverify
		      If  set, and readline is being used, the results of his
		      tory substitution are  not  immediately  passed  to  the
		      shell  parser.   Instead,  the  resulting line is loaded
		      into the readline editing buffer, allowing further modi
		      fication.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to
		      perform hostname completion when a word containing  a  @
		      is   being  completed  (see  Completing  under  READLINE
		      above).  This is enabled by default.
	      huponexit
		      If set, bash will send SIGHUP to all jobs when an inter
		      active login shell exits.
	      interactive_comments
		      If set, allow a word beginning with # to cause that word
		      and all remaining characters on that line to be  ignored
		      in  an  interactive  shell  (see	COMMENTS above).  This
		      option is enabled by default.
	      lithist If set, and the cmdhist option  is  enabled,  multi-line
		      commands are saved to the history with embedded newlines
		      rather than using semicolon separators where possible.
	      login_shell
		      The shell sets this option if it is started as  a  login
		      shell  (see  INVOCATION  above).	 The  value may not be
		      changed.
	      mailwarn
		      If set, and a file that bash is checking	for  mail  has
		      been  accessed  since  the last time it was checked, the
		      message The mail in mailfile has been read  is  dis
		      played.
	      no_empty_cmd_completion
		      If  set,	and  readline  is  being  used,  bash will not
		      attempt to search the PATH for possible completions when
		      completion is attempted on an empty line.
	      nocaseglob
		      If  set,	bash  matches  filenames in a case-insensitive
		      fashion when performing pathname expansion (see Pathname
		      Expansion above).
	      nocasematch
		      If  set,	bash  matches  patterns  in a case-insensitive
		      fashion when performing matching while executing case or
		      [[ conditional commands.
	      nullglob
		      If  set,	bash allows patterns which match no files (see
		      Pathname Expansion above) to expand to  a  null  string,
		      rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Pro
		      grammable Completion above) are enabled.	This option is
		      enabled by default.
	      promptvars
		      If set, prompt strings undergo parameter expansion, com
		      mand  substitution,  arithmetic  expansion,  and	 quote
		      removal  after  being expanded as described in PROMPTING
		      above.  This option is enabled by default.
	      restricted_shell
		      The  shell  sets	this  option  if  it  is  started   in
		      restricted mode (see RESTRICTED SHELL below).  The value
		      may not be changed.  This is not reset when the  startup
		      files  are  executed, allowing the startup files to dis
		      cover whether or not a shell is restricted.
	      shift_verbose
		      If set, the shift builtin prints an error  message  when
		      the shift count exceeds the number of positional parame
		      ters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to
		      find  the  directory  containing the file supplied as an
		      argument.  This option is enabled by default.
	      xpg_echo
		      If  set,	the  echo  builtin  expands   backslash-escape
		      sequences by default.
       suspend [-f]
	      Suspend  the execution of this shell until it receives a SIGCONT
	      signal.  The -f option says not to complain if this is  a  login
	      shell;  just  suspend anyway.  The return status is 0 unless the
	      shell is a login shell and -f is not supplied, or if job control
	      is not enabled.
       test expr
       [ expr ]
	      Return  a  status  of  0 or 1 depending on the evaluation of the
	      conditional expression expr.  Each operator and operand must  be
	      a  separate argument.  Expressions are composed of the primaries
	      described above under CONDITIONAL EXPRESSIONS.   test  does  not
	      accept any options, nor does it accept and ignore an argument of
	      -- as signifying the end of options.

	      Expressions may  be  combined  using  the  following  operators,
	      listed in decreasing order of precedence.
	      ! expr True if expr is false.
	      ( expr )
		     Returns  the value of expr.  This may be used to override
		     the normal precedence of operators.
	      expr1 -a expr2
		     True if both expr1 and expr2 are true.
	      expr1 -o expr2
		     True if either expr1 or expr2 is true.

	      test and [ evaluate conditional expressions using a set of rules
	      based on the number of arguments.

	      0 arguments
		     The expression is false.
	      1 argument
		     The expression is true if and only if the argument is not
		     null.
	      2 arguments
		     If the first argument is !, the expression is true if and
		     only  if  the  second  argument  is  null.   If the first
		     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 eval
		     uated  according  to  precedence  using  the rules listed
		     above.
	      5 or more arguments
		     The expression  is  parsed  and  evaluated  according  to
		     precedence using the rules listed above.

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

       trap [-lp] [[arg] sigspec ...]
	      The command arg is to  be  read  and  executed  when  the  shell
	      receives	signal(s)  sigspec.   If arg is absent (and there is a
	      single sigspec) or -, each specified  signal  is	reset  to  its
	      original	disposition  (the  value  it  had upon entrance to the
	      shell).  If arg is the null string the signal specified by  each
	      sigspec  is ignored by the shell and by the commands it invokes.
	      If arg is not present and -p has been supplied,  then  the  trap
	      commands	associated  with  each	sigspec  are displayed.  If no
	      arguments are supplied or if only -p is given, trap  prints  the
	      list  of	commands  associated  with each signal.  The -l option
	      causes the shell to print a list of signal names and their  cor
	      responding  numbers.   Each  sigspec  is	either	a  signal name
	      defined in , or a signal  number.   Signal  names  are
	      case  insensitive  and the SIG prefix is optional.  If a sigspec
	      is EXIT (0) the command arg is executed on exit from the	shell.
	      If  a sigspec is DEBUG, the command arg is executed before every
	      simple command, for command, case command, select command, every
	      arithmetic for command, and before the first command executes in
	      a shell function	(see  SHELL  GRAMMAR  above).	Refer  to  the
	      description  of  the  extdebug  option  to the shopt builtin for
	      details of its effect on the DEBUG trap.	If a sigspec  is  ERR,
	      the  command  arg  is  executed  whenever a simple command has a
	      non-zero exit status, subject to the following conditions.   The
	      ERR  trap  is  not executed if the failed command is part of the
	      command list immediately following a  while  or  until  keyword,
	      part of the test in an if statement, part of a && or  list, or
	      if the commands return value is being inverted  via  !.	These
	      are  the	same  conditions  obeyed  by the errexit option.  If a
	      sigspec is RETURN, the command arg is executed each time a shell
	      function or a script executed with the . or source builtins fin
	      ishes executing.	Signals ignored upon entry to the shell cannot
	      be  trapped or reset.  Trapped signals are reset to their origi
	      nal values in a child process when it is	created.   The	return
	      status  is  false  if  any  sigspec  is  invalid; otherwise trap
	      returns true.

       type [-aftpP] name [name ...]
	      With no options, indicate how each name would be interpreted  if
	      used as a command name.  If the -t option is used, type prints a
	      string which is one of alias,  keyword,  function,  builtin,  or
	      file  if	name  is  an  alias,  shell  reserved  word, function,
	      builtin, or disk file, respectively.  If the name is not	found,
	      then  nothing  is  printed,  and	an  exit  status  of  false is
	      returned.  If the -p option is used,  type  either  returns  the
	      name of the disk file that would be executed if name were speci
	      fied as a command name, or nothing if type -t name would not
	      return  file.  The -P option forces a PATH search for each name,
	      even if type -t name would not return file.  If a command is
	      hashed,  -p  and	-P print the hashed value, not necessarily the
	      file that appears first in PATH.	If the -a option is used, type
	      prints  all of the places that contain an executable named name.
	      This includes aliases and functions,  if	and  only  if  the  -p
	      option  is  not  also used.  The table of hashed commands is not
	      consulted when using -a.	The -f option suppresses  shell  func
	      tion  lookup, as with the command builtin.  type returns true if
	      any of the arguments are found, false if none are found.

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

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

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

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

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

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

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

	     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 >> redirec
	      tion 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

	     Using the	enable	builtin  command  to  enable  disabled	shell
	      builtins

	     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 COM
       MAND EXECUTION above), rbash turns off any restrictions	in  the  shell
       spawned to execute the script.

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

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

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

       Chet Ramey, Case Western Reserve University
       chet@po.cwru.edu

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

       Once you have determined that a bug actually exists,  use  the  bashbug
       command	to submit a bug report.  If you have a fix, you are encouraged
       to mail that as well!  Suggestions and philosophical bug reports  may
       be  mailed  to  bug-bash@gnu.org  or  posted  to  the  Usenet newsgroup
       gnu.bash.bug.

       ALL bug reports should include:

       The version number of bash
       The hardware and operating system
       The compiler used to compile
       A description of the bug behaviour
       A short script or recipe which exercises the bug

       bashbug inserts the first three items automatically into  the  template
       it provides for filing a bug report.

       Comments and bug reports concerning this manual page should be directed
       to chet@po.cwru.edu.

BUGS
       Its too big and too slow.

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

       Aliases are confusing in some uses.

       Shell builtin commands and functions are not stoppable/restartable.

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

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

       Array variables may not (yet) be exported.



GNU Bash-3.1			  2005 Dec 28			       BASH(1)




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