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RedHat 9 (Linux i386) - man page for sh (redhat section 1)

BASH(1) 			     General Commands Manual				  BASH(1)

NAME
       bash - GNU Bourne-Again SHell

SYNOPSIS
       bash [options] [file]

COPYRIGHT
       Bash is Copyright (C) 1989-2002 by the Free Software Foundation, Inc.

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

       Bash is intended to be a conformant implementation of the IEEE POSIX Shell and Tools spec-
       ification (IEEE Working Group 1003.2).

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

       -c string If  the  -c option is present, then commands are read from string.  If there are
		 arguments after the string, they are  assigned  to  the  positional  parameters,
		 starting with $0.
       -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 posi-
		 tional parameters to be set when invoking an interactive shell.
       -D	 A list of all double-quoted strings preceded by $ is  printed	on  the  standard
		 ouput.   These are the strings that are subject to language translation when the
		 current locale is not C or POSIX.  This implies the -n option; no commands  will
		 be executed.
       [-+]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 val-
		 ues 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 filenames and arguments.  An argument of -
		 is equivalent to --.

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

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

       --login
	      Equivalent to -l.

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

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

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

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

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

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

       --version
	      Show  version information for this instance of bash on the standard output and exit
	      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 com-
       mands.  If bash is invoked in this fashion, $0 is set to the name of  the  file,  and  the
       positional  parameters  are  set to the remaining arguments.  Bash reads and executes com-
       mands from this file, then exits.  Bash's exit status is the exit status of the last  com-
       mand  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  output  are  both  connected  to  terminals (as determined by
       isatty(3)), or one started with the -i option.  PS1 is set and $- includes i  if  bash  is
       interactive, allowing a shell script or a startup file to test this state.

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

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

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

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

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

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

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

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

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

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

RESERVED WORDS
       Reserved words are words that have a special meaning to the shell.   The  following  words
       are  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 followed by blank-sepa-
       rated words and redirections, and terminated by a control operator.  The first word speci-
       fies  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 termi-
       nated by signal n.

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

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

       The standard output of command is connected via a pipe to the standard input of	command2.
       This  connection  is performed before any redirections specified by the command (see REDI-
       RECTION below).

       If the reserved word !  precedes a pipeline, the exit status of that pipeline is the logi-
       cal  NOT of the exit status of the last command.  Otherwise, the status of the pipeline is
       the exit status of the last command.  The shell waits for all commands in the pipeline  to
       terminate before returning a value.

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

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

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

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

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

       If a command is terminated by the control operator &, the shell executes  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, respectively.  An AND  list
       has the form

	      command1 && command2

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

       An OR list has the form

	      command1 || command2

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

   Compound Commands
       A compound command is one of the following:

       (list) list is executed in a subshell.  Variable assignments  and  builtin  commands  that
	      affect the shell's environment do not remain in effect after the command completes.
	      The return status is the exit status of list.

       { list; }
	      list is simply executed in the current shell environment.  list must be  terminated
	      with  a 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 recog-
	      nized.  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 expression is non-zero, the return  status  is  0;
	      otherwise the return status is 1.  This is exactly equivalent to let "expression".

       [[ expression ]]
	      Return a status of 0 or 1 depending on the evaluation of the conditional expression
	      expression.  Expressions are composed of the primaries described below under CONDI-
	      TIONAL EXPRESSIONS.  Word splitting and pathname expansion are not performed on the
	      words between the [[ and ]]; tilde expansion,  parameter	and  variable  expansion,
	      arithmetic expansion, command substitution, process substitution, and quote removal
	      are performed.

	      When the == and != operators are used, the string to the right of the  operator  is
	      considered  a pattern and matched according to the rules described below under Pat-
	      tern Matching.  The return value is 0 if the string matches or does not  match  the
	      pattern,	respectively,  and 1 otherwise.  Any part of the pattern may be quoted to
	      force it to be matched as a string.

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

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

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

       for name [ in word ] ; do list ; done
	      The  list of words following in is expanded, generating a list of items.	The vari-
	      able name is set to each element of this list in turn, and list  is  executed  each
	      time.  If the in word is omitted, the for command executes list once for each posi-
	      tional 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 evalu-
	      ated.  If any expression is omitted, it behaves as  if  it  evaluates  to  1.   The
	      return  value  is  the exit status of the last command in list that is executed, or
	      false if any of the expressions is invalid.

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

       case word in [ [(] pattern [ | pattern ] ... ) list ;; ] ... esac
	      A case command first expands word, and tries to match it against	each  pattern  in
	      turn,  using the same matching rules as for pathname expansion (see Pathname Expan-
	      sion below).  When a match is found, the corresponding list is executed.	After the
	      first  match,  no  subsequent matches are attempted.  The exit status is zero if no
	      pattern matches.	Otherwise, it is the exit status of the last command executed  in
	      list.

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

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

       [ function ] name () { list; }
	      This defines a function named name.  The body of the function is the list  of  com-
	      mands  between  {  and  }.  This list is executed whenever name is specified as the
	      name of a simple command.  The exit status of a function is the exit status of  the
	      last command executed in the body.  (See FUNCTIONS below.)

COMMENTS
       In  a  non-interactive  shell,  or  an interactive shell in which the interactive_comments
       option to the shopt builtin is enabled (see SHELL BUILTIN COMMANDS below), a  word  begin-
       ning  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 interactive shells.

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

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

       When the command history expansion facilities are being used, the history expansion  char-
       acter, usually !, must be quoted to prevent history expansion.

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

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

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

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

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

       Words of the form $'string' are treated specially.  The word expands to string, with back-
       slash-escaped  characters  replaced  as specifed by the ANSI C standard.  Backslash escape
       sequences, if present, are decoded as follows:
	      \a     alert (bell)
	      \b     backspace
	      \e     an escape character
	      \f     form feed
	      \n     new line
	      \r     carriage return
	      \t     horizontal tab
	      \v     vertical tab
	      \\     backslash
	      \'     single quote
	      \nnn   the eight-bit character whose value is the octal value  nnn  (one	to  three
		     digits)
	      \xHH   the  eight-bit character whose value is the hexadecimal value HH (one or two
		     hex digits)
	      \cx    a control-x character

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

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

PARAMETERS
       A  parameter  is  an entity that stores values.	It can be a name, a number, or one of the
       special characters listed below under Special Parameters.  For  the  shell's  purposes,	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, command substitution,  arithmetic  expansion,
       and  quote  removal (see EXPANSION below).  If the variable has its integer attribute set,
       then value is subject to arithmetic expansion even if the $((...)) expansion is	not  used
       (see  Arithmetic Expansion below).  Word splitting is not performed, with the exception of
       "$@" as explained below under Special Parameters.  Pathname expansion  is  not  performed.
       Assignment  statements may also appear as arguments to the declare, typeset, export, read-
       only, and local builtin commands.

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

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

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

   Shell Variables
       The following variables are set by the shell:

       BASH   Expands to the full file name used to invoke this instance of bash.
       BASH_VERSINFO
	      A readonly array variable whose members hold version information for this  instance
	      of bash.	The values assigned to the array members are as follows:
	      BASH_VERSINFO[0]	      The major version number (the release).
	      BASH_VERSINFO[1]	      The minor version number (the version).
	      BASH_VERSINFO[2]	      The patch level.
	      BASH_VERSINFO[3]	      The build version.
	      BASH_VERSINFO[4]	      The release status (e.g., beta1).
	      BASH_VERSINFO[5]	      The value of MACHTYPE.

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

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

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

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

       COMP_WORDS
	      An array variable (see Arrays below) consisting of the individual words in the cur-
	      rent command line.  This variable is available only in shell functions  invoked  by
	      the programmable completion facilities (see Programmable Completion below).

       DIRSTACK
	      An  array variable (see Arrays below) containing the current contents of the direc-
	      tory 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
	      directories already in the stack, but the pushd and popd builtins must be  used  to
	      add  and	remove directories.  Assignment to this variable will not change the cur-
	      rent directory.  If DIRSTACK is unset, it loses its special properties, even if  it
	      is subsequently reset.

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

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

       GROUPS An array variable containing the list of groups of which the current user is a mem-
	      ber.  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 rep-
	      resenting  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  guaran-
	      teed  to	be meaningful.	If LINENO is unset, it loses its special properties, 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-company-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 system on which bash  is
	      executing.  The default is system-dependent.

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

       PPID   The process ID of the shell's parent.  This variable is readonly.

       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 sub-
	      sequently 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 invoca-
	      tion is returned.  If a value is assigned to SECONDS, the value returned upon  sub-
	      sequent  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 sub-
	      sequently 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 inter-
	      preted 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 completion facility (see Programmable
	      Completion below).
       FCEDIT The default editor for the fc builtin command.
       FIGNORE
	      A colon-separated list of suffixes to ignore when  performing  filename  completion
	      (see  READLINE  below).  A filename whose suffix matches one of the entries in FIG-
	      NORE is excluded from the list of matched filenames.  A sample value is ".o:~".
       GLOBIGNORE
	      A colon-separated list of patterns defining the set of filenames to be  ignored  by
	      pathname	expansion.   If  a  filename matched by a pathname expansion pattern also
	      matches one of the patterns in GLOBIGNORE, it is removed from the list of matches.
       HISTCONTROL
	      If set to a value of ignorespace, lines which begin with a space character are  not
	      entered  on  the history list.  If set to a value of ignoredups, lines matching the
	      last history line are not entered.  A value of ignoreboth combines the two options.
	      If  unset,  or  if  set  to any other value than those above, all lines read by the
	      parser are saved on the history list, subject to the  value  of  HISTIGNORE.   This
	      variable's  function  is superseded by HISTIGNORE.  The second and subsequent lines
	      of a multi-line compound command are not tested,	and  are  added  to  the  history
	      regardless of the value of HISTCONTROL.
       HISTFILE
	      The  name  of  the file in which command history is saved (see HISTORY below).  The
	      default value is ~/.bash_history.  If unset, the command history is not saved  when
	      an interactive shell exits.
       HISTFILESIZE
	      The  maximum  number of lines contained in the history file.  When this variable is
	      assigned a value, the history file is truncated, if necessary, to contain  no  more
	      than  that  number  of  lines.  The default value is 500.  The history file is also
	      truncated to this size after 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 complete line (no implicit `*' is appended).	Each  pattern  is
	      tested  against the line after the checks specified by HISTCONTROL are applied.  In
	      addition to the normal shell pattern matching 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  com-
	      pound  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.
       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 comple-
	      tions may be changed while the shell is running; the next time hostname  completion
	      is  attempted after the value is changed, bash adds the contents of the new file to
	      the existing list.  If HOSTFILE is set, but has no value,  bash  attempts  to  read
	      /etc/hosts  to  obtain the list of possible hostname completions.  When HOSTFILE is
	      unset, the hostname list is cleared.
       IFS    The Internal Field Separator that is used for word splitting after expansion and to
	      split  lines  into  words  with  the  read  builtin  command.  The default value is
	      ``<space><tab><newline>''.
       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 path-
	      name 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 char-
	      acter classes within pathname expansion and pattern matching.
       LC_MESSAGES
	      This variable determines the locale used to translate  double-quoted  strings  pre-
	      ceded 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 variable is not set,  bash
	      informs the user of the arrival of mail in the specified file.
       MAILCHECK
	      Specifies  how often (in seconds) bash checks for mail.  The default is 60 seconds.
	      When it is time to check for mail, the shell does so before displaying the  primary
	      prompt.	If this 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 location of the user mail
	      files that it uses is system dependent (e.g., /var/mail/$USER).
       OPTERR If set to the value 1, bash  displays  error  messages  generated  by  the  getopts
	      builtin  command	(see  SHELL  BUILTIN COMMANDS below).  OPTERR is initialized to 1
	      each time the shell is invoked or a shell script is executed.
       PATH   The search path for commands.  It is a colon-separated list of directories in which
	      the  shell  looks  for commands (see COMMAND EXECUTION below).  The default path is
	      system-dependent, and is set by the administrator  who  installs	bash.	A  common
	      value is ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.''.
       POSIXLY_CORRECT
	      If  this	variable  is  in the environment when bash starts, the shell enters posix
	      mode before reading the startup files, as if the --posix invocation option had been
	      supplied.   If it is set while the shell is running, bash enables posix mode, as if
	      the command set -o posix had been executed.
       PROMPT_COMMAND
	      If set, the value is executed as a command prior to issuing each primary prompt.
       PS1    The value of this parameter is expanded (see PROMPTING below) and used as the  pri-
	      mary 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 multiple times, as necessary, to indicate multiple levels of indirec-
	      tion.  The default is ``+ ''.
       TIMEFORMAT
	      The value of this parameter is used as a format string specifying  how  the  timing
	      information for pipelines prefixed with the time reserved word should be displayed.
	      The % character introduces an escape sequence that is expanded to a time	value  or
	      other  information.   The  escape  sequences and their meanings are as follows; the
	      braces denote optional portions.
	      %%	A literal %.
	      %[p][l]R	The elapsed time in seconds.
	      %[p][l]U	The number of CPU seconds spent in user mode.
	      %[p][l]S	The number of CPU seconds spent in system mode.
	      %P	The CPU percentage, computed as (%U + %S) / %R.

	      The optional p is a digit specifying the precision, the number of fractional digits
	      after a decimal point.  A value of 0 causes no decimal point or fraction to be out-
	      put.  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 terminates 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.

       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 sup-
	      plied needs to match a substring of the name of a stopped job.  The substring value
	      provides functionality analogous to the %?  job identifier (see JOB CONTROL below).
	      If set to any other value, the supplied string must be a prefix of a stopped  job's
	      name; this provides functionality analogous to the % job identifier.

       histchars
	      The  two	or three characters which control history expansion and tokenization (see
	      HISTORY EXPANSION below).  The first character is the history expansion  character,
	      the  character  which  signals the start of a history expansion, normally `!'.  The
	      second character is the quick substitution character, which is  used  as	shorthand
	      for re-running the previous command entered, substituting one string for another in
	      the command.  The default is `^'.  The optional third character  is  the	character
	      which indicates that the remainder of the line is a comment when found as the first
	      character of a word, normally `#'.  The history comment  character  causes  history
	      substitution to be skipped for the remaining words on the line.  It does not neces-
	      sarily 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 [subscript]=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 separate word.  When there are no array
       members, ${name[@]} expands to nothing.	This is analogous to the expansion of the special
       parameters  *  and  @  (see Special Parameters above).  ${#name[subscript]} expands to the
       length of ${name[subscript]}.  If subscript is * or @, the expansion is the number of 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.  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  vari-
       able  expansion,  command substitution, arithmetic expansion, word splitting, and pathname
       expansion.

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

       On systems that can support it, there is an additional expansion available:  process  sub-
       stitution.

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

   Brace Expansion
       Brace expansion is a mechanism by which arbitrary strings may be generated.   This  mecha-
       nism  is  similar to pathname expansion, but the filenames generated need not exist.  Pat-
       terns to be brace expanded take the form of an optional preamble, followed by a series  of
       comma-separated strings between a pair of braces, followed by an optional postscript.  The
       preamble is prefixed to each string contained within the braces,  and  the  postscript  is
       then appended to each resulting string, expanding left to right.

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

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

       A  correctly-formed  brace expansion must contain unquoted opening and closing braces, and
       at least one unquoted comma.  Any incorrectly formed brace expansion is left unchanged.	A
       {  or  ,  may  be  quoted with a backslash to prevent its being considered part of a brace
       expression.  To avoid conflicts with parameter expansion, the string ${ is not  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 out-
       put.  The same word is output as file1 file2 after expansion by bash.  If strict  compati-
       bility  with  sh is desired, start bash with the +B option or disable brace expansion with
       the +B option to the set command (see SHELL BUILTIN COMMANDS below).

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

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

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

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

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

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

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

       If the first character of parameter is an exclamation point, a level of variable  indirec-
       tion is introduced.  Bash uses the value of the variable formed from the rest of parameter
       as the name of the variable; this variable is then expanded and that value is used in  the
       rest  of  the  substitution,  rather than the value of parameter itself.  This is known as
       indirect expansion.  The exception to this  is  the  expansion  of  ${!prefix*}	described
       below.

       In  each of the cases below, word is subject to tilde expansion, parameter expansion, com-
       mand 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 parameter that is unset.

       ${parameter:-word}
	      Use Default Values.  If parameter is unset or null, the expansion of word  is  sub-
	      stituted.  Otherwise, the value of parameter is substituted.
       ${parameter:=word}
	      Assign  Default  Values.	 If  parameter is unset or null, the expansion of word is
	      assigned to parameter.  The value of parameter  is  then	substituted.   Positional
	      parameters and special parameters may not be assigned to in this way.
       ${parameter:?word}
	      Display  Error  if  Null or Unset.  If parameter is null or unset, the expansion of
	      word (or a message to that effect if word is not present) is written to  the  stan-
	      dard 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, other-
	      wise 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 starting at the character specified by offset.  length and offset are
	      arithmetic expressions (see ARITHMETIC EVALUATION below).  length must evaluate  to
	      a  number greater than or equal to zero.	If offset evaluates to a number less than
	      zero, the value is used as an offset from the end of the value  of  parameter.   If
	      parameter is @, the result is length positional parameters 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]}.  Substring indexing is zero-based
	      unless the positional parameters are used, in which case the indexing starts at 1.

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

       ${#parameter}
	      The length in characters of the value of parameter is substituted.  If parameter is
	      * or @, the value substituted is the number of positional parameters.  If parameter
	      is an array name subscripted by * or @, the value substituted is the number of ele-
	      ments 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 match-
	      ing 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  parame-
	      ter  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.  Param-
	      eter is expanded and the longest match of pattern against  its  value  is  replaced
	      with string.  In the first form, only the first match is replaced.  The second form
	      causes all matches of pattern to be replaced with string.  If pattern  begins  with
	      #,  it  must match at the beginning of the expanded value of parameter.  If pattern
	      begins with %, it must match at the end of the expanded  value  of  parameter.   If
	      string  is  null, matches of pattern are deleted and the / following pattern may be
	      omitted.	If parameter is @ or *, the substitution operation  is	applied  to  each
	      positional  parameter in turn, and the expansion is the resultant list.  If parame-
	      ter is an array variable subscripted with @ or *,  the  substitution  operation  is
	      applied  to  each  member  of the array in turn, and the expansion is the resultant
	      list.

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

	      $(command)
       or
	      `command`

       Bash  performs  the  expansion by executing command and replacing the command substitution
       with the standard output of the command, with any  trailing  newlines  deleted.	 Embedded
       newlines are not deleted, but they may be removed during word splitting.  The command sub-
       stitution $(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 back-
       slash terminates the command substitution.  When using the $(command) form, all characters
       between the parentheses make up the command; none are treated specially.

       Command	substitutions  may be nested.  To nest when using the backquoted form, escape the
       inner 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 substitu-
       tion of the result.  The format for arithmetic expansion is:

	      $((expression))

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

       The  evaluation	is performed according to the rules listed below under ARITHMETIC EVALUA-
       TION.  If expression is invalid, bash prints a message indicating failure and no substitu-
       tion occurs.

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

       When  available, process substitution is performed simultaneously with parameter and vari-
       able expansion, command substitution, and arithmetic expansion.

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

       The shell treats each character of IFS as a delimiter, and splits the results of the other
       expansions into words on these characters.  If IFS is  unset,  or  its  value  is  exactly
       <space><tab><newline>,  the default, then any sequence of IFS characters serves to delimit
       words.  If IFS has a value other than the default, then sequences of the whitespace  char-
       acters  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 parame-
       ter  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 pat-
       tern.  If no matching file names are found, and the shell option nullglob is disabled, the
       word is left unchanged.	If the nullglob option is set, and no matches are found, the word
       is  removed.   If  the  shell option nocaseglob is enabled, the match is performed without
       regard to the case of alphabetic characters.  When a pattern is used for  pathname  expan-
       sion, the character ``.''  at the start of a name or immediately following a slash must be
       matched explicitly, unless the shell option dotglob is set.  When matching a pathname, the
       slash  character  must always be matched explicitly.  In other cases, the ``.''	character
       is not treated specially.  See the description of shopt below under SHELL BUILTIN COMMANDS
       for a description of the nocaseglob, nullglob, and dotglob shell options.

       The  GLOBIGNORE	shell  variable  may be used to restrict the set of file names matching a
       pattern.  If GLOBIGNORE is set, each matching file name that also matches one of the  pat-
       terns in GLOBIGNORE is removed from the list of matches.  The file names ``.''  and ``..''
       are always ignored, even when GLOBIGNORE is set.   However,  setting  GLOBIGNORE  has  the
       effect  of  enabling  the  dotglob  shell option, so all other file names beginning with a
       ``.''  will match.  To get the old behavior of ignoring file names beginning with a ``.'',
       make  ``.*''  one of the patterns in GLOBIGNORE.  The dotglob option is disabled when GLO-
       BIGNORE is unset.

       Pattern Matching

       Any character that appears in  a  pattern,  other  than	the  special  pattern  characters
       described  below, matches itself.  The NUL character may not occur in a pattern.  The spe-
       cial pattern characters must be quoted if they are to be matched literally.

       The special pattern characters have the following meanings:

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

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

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

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

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

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

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

REDIRECTION
       Before a command is executed, its input and output may be redirected using a special nota-
       tion 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 pro-
       cessed in the order they appear, from left to right.

       In  the	following  descriptions,  if the file descriptor number is omitted, and the first
       character of the redirection operator is <, the redirection refers to the  standard  input
       (file  descriptor  0).  If the first character of the redirection operator is >, the redi-
       rection refers to the standard output (file descriptor 1).

       The word following the redirection operator in the following descriptions,  unless  other-
       wise noted, is subjected to brace expansion, tilde expansion, parameter expansion, command
       substitution, arithmetic expansion, quote removal, pathname expansion, and word splitting.
       If it expands to more than one word, bash reports an error.

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

	      ls > dirlist 2>&1

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

	      ls 2>&1 > dirlist

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

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

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

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

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

       The general format for redirecting input is:

	      [n]<word

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

       The general format for redirecting output is:

	      [n]>word

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

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

       The general format for appending output is:

	      [n]>>word

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

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

	      &>word
       and
	      >&word

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

	      >word 2>&1

   Here Documents
       This type of redirection instructs the shell to read input from the current source until a
       line  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, command
       substitution, and arithmetic expansion.	In the latter case, the character sequence \<new-
       line> is ignored, and \ must be used to quote the characters \, $, and `.

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

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

	      <<<word

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

   Duplicating File Descriptors
       The redirection operator

	      [n]<&word

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

       The operator

	      [n]>&word

       is  used similarly to duplicate output file descriptors.  If n is not specified, the stan-
       dard 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 omit-
       ted, 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 descrip-
       tor 0) if n is not specified.  digit is closed after being duplicated to n.

       Similarly, the redirection operator

	      [n]>&digit-

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

   Opening File Descriptors for Reading and Writing
       The redirection operator

	      [n]<>word

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

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

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

       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.  There-
       fore, 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 func-
       tions are executed.  Aliases are expanded when a function definition is read, not when the
       function is executed, because a function definition is itself a compound  command.   As	a
       consequence,  aliases defined in a function are not available until after that function is
       executed.  To be safe, always put alias definitions on a separate line,	and  do  not  use
       alias in compound commands.

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

FUNCTIONS
       A  shell function, defined as described above under SHELL GRAMMAR, stores a series of com-
       mands 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 spe-
       cial  parameter	# is updated to reflect the change.  Positional parameter 0 is unchanged.
       The FUNCNAME variable is set to the name of the function while the function is  executing.
       All  other aspects of the shell execution environment are identical between a function and
       its caller with the exception that the DEBUG trap (see the description of the trap builtin
       under  SHELL  BUILTIN  COMMANDS below) is not inherited unless the function has been given
       the trace attribute (see the description of the declare builtin below).

       Variables local to the function may be declared with the local builtin command.	 Ordinar-
       ily, 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 execu-
       tion resumes with the next command after the function call.  When  a  function  completes,
       the  values  of	the positional parameters and the special parameter # are restored to the
       values they had prior to the function's execution.

       Function names and definitions may be listed with the -f option to the declare or  typeset
       builtin	commands.  The -F option to declare or typeset will list the function names only.
       Functions may be exported so that subshells automatically have them defined  with  the  -f
       option to the export builtin.

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

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

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

       Shell variables are allowed as operands;  parameter  expansion  is  performed  before  the
       expression  is evaluated.  Within an expression, shell variables may also be referenced by
       name without using the parameter expansion syntax.  The value of a variable  is	evaluated
       as  an  arithmetic  expression  when it is referenced.  A shell variable need not have its
       integer attribute turned on to be used in an expression.

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

       Operators are evaluated in order of precedence.	Sub-expressions in parentheses are evalu-
       ated 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.   Expres-
       sions  are  formed  from the following unary or binary primaries.  If any file argument to
       one of the primaries is of the form /dev/fd/n, then file descriptor n is checked.  If  the
       file  argument  to one of the primaries is one of /dev/stdin, /dev/stdout, or /dev/stderr,
       file descriptor 0, 1, or 2, respectively, is checked.

       -a file
	      True if file exists.
       -b file
	      True if file exists and is a block special file.
       -c file
	      True if file exists and is a character special file.
       -d file
	      True if file exists and is a directory.
       -e file
	      True if file exists.
       -f file
	      True if file exists and is a regular file.
       -g file
	      True if file exists and is set-group-id.
       -h file
	      True if file exists and is a symbolic link.
       -k file
	      True if file exists and its ``sticky'' bit is set.
       -p file
	      True if file exists and is a named pipe (FIFO).
       -r file
	      True if file exists and is readable.
       -s file
	      True if file exists and has a size greater than zero.
       -t fd  True if file descriptor fd is open and refers to a terminal.
       -u file
	      True if file exists and its set-user-id bit is set.
       -w file
	      True if file exists and is writable.
       -x file
	      True if file exists and is executable.
       -O file
	      True if file exists and is owned by the effective user id.
       -G file
	      True if file exists and is owned by the effective group id.
       -L file
	      True if file exists and is a symbolic link.
       -S file
	      True if file exists and is a socket.
       -N file
	      True if file exists and has been modified since it was last read.
       file1 -nt file2
	      True if file1 is newer (according to modification date) than  file2,  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 numbers.
       -o optname
	      True  if	shell  option  optname	is  enabled.   See  the list of options under the
	      description of the -o option to the set builtin below.
       -z string
	      True if the length of string is zero.
       -n string
       string True if the length of string is non-zero.
       string1 == string2
	      True if the strings are equal.  = may be used in place of == for strict POSIX  com-
	      pliance.
       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,  assign-
       ments, 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, parame-
	      ter expansion, command substitution, arithmetic expansion, and quote removal before
	      being assigned to the variable.

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

       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 expansions contained a command  substitution,
       the  exit  status  of the command is the exit status of the last command substitution per-
       formed.	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 containing an executable file by that
       name.  Bash uses a hash table to remember the full pathnames of executable files (see hash
       under  SHELL  BUILTIN  COMMANDS	below).  A full search of the directories in PATH is per-
       formed only if the command is not found in the hash table.  If the search is unsuccessful,
       the shell prints an error message and returns an exit status of 127.

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

       If this execution fails because the file is not in executable format, and the file is  not
       a directory, it is assumed to be a shell script, a file containing shell commands.  A sub-
       shell 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 loca-
       tions 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 executable format themselves.  The arguments to the inter-
       preter 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 argu-
       ments, if any.

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

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

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

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

       o      current traps set by trap

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

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

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

       o      options enabled by shopt

       o      shell aliases defined with alias

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

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

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

       o      the current working directory

       o      the file creation mode mask

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

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

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

       Command substitution and asynchronous 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 subshell environment cannot affect the shell's execution environment.

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

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

       The  shell  provides several ways to manipulate the environment.  On invocation, the shell
       scans its own environment and creates a parameter for each name found, automatically mark-
       ing  it	for  export  to child processes.  Executed commands inherit the environment.  The
       export and declare -x commands allow parameters and functions to be added to  and  deleted
       from the environment.  If the value of a parameter in the environment is modified, the new
       value becomes part of the environment, replacing the old.  The  environment  inherited  by
       any executed command consists of the shell's initial environment, whose values may be mod-
       ified 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 prefix-
       ing it with parameter assignments, as described above  in  PARAMETERS.	These  assignment
       statements affect only the environment seen by that command.

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

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

EXIT STATUS
       For the shell's purposes, a command which exits with a zero exit status has succeeded.  An
       exit  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.

       Synchronous  jobs  started by bash have signal handlers set to the values inherited by the
       shell from its parent.  When job control is not in effect,  asynchronous  commands  ignore
       SIGINT  and  SIGQUIT as well.  Commands run as a result of command substitution ignore the
       keyboard-generated job control signals SIGTTIN, SIGTTOU, and SIGTSTP.

       The shell exits by default upon receipt of a SIGHUP.  Before exiting, 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.

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

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

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

	      [1] 25647

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

       To facilitate the implementation of the user interface to job control, the operating  sys-
       tem  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 termi-
       nal's; such processes are immune to keyboard-generated 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 terminal
       driver, which, unless caught, suspends the process.

       If the operating system on which bash is  running  supports  job  control,  bash  contains
       facilities  to  use  it.   Typing  the suspend character (typically ^Z, Control-Z) while a
       process is running causes that process to be stopped and returns control to bash.   Typing
       the  delayed  suspend character (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 character %  introduces	a
       job  name.   Job number n may be referred to as %n.  A job may also be referred to using a
       prefix of the name used to start it, or using a substring  that	appears  in  its  command
       line.   For  example,  %ce  refers to a stopped ce job.	If a prefix matches more than one
       job, bash reports an error.  Using %?ce, on the other hand, refers to any  job  containing
       the  string  ce	in  its  command  line.  If the substring matches more than one job, bash
       reports an error.  The symbols %% and %+ refer to the shell's notion of the  current  job,
       which is the last job stopped while it was in the foreground or started in the background.
       The previous job may be referenced using %-.  In output pertaining to jobs (e.g., the out-
       put of the jobs command), the current job is always flagged with a +, and the previous job
       with a -.

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

       The shell learns immediately whenever a job changes state.  Normally, bash waits until  it
       is  about to print a prompt before reporting changes in a job's status so as to not inter-
       rupt 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 mes-
       sage.   The jobs command may then be used to inspect their status.  If a second attempt to
       exit is made without an intervening command, the shell does not print another warning, and
       the stopped jobs are 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  com-
       mand.   Bash  allows  these prompt strings to be customized by inserting a number of back-
       slash-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 representa-
		     tion.  The braces are required
	      \e     an ASCII escape character (033)
	      \h     the hostname up to the first `.'
	      \H     the hostname
	      \j     the number of jobs currently managed by the shell
	      \l     the basename of the shell's terminal device name
	      \n     newline
	      \r     carriage return
	      \s     the name of the shell, the basename of $0 (the portion following  the  final
		     slash)
	      \t     the current time in 24-hour HH:MM:SS format
	      \T     the current time in 12-hour HH:MM:SS format
	      \@     the current time in 12-hour am/pm format
	      \A     the current time in 24-hour HH:MM format
	      \u     the username of the current user
	      \v     the version of bash (e.g., 2.00)
	      \V     the release of bash, version + patchelvel (e.g., 2.00.0)
	      \w     the current working directory
	      \W     the basename of the current working directory
	      \!     the history number of this command
	      \#     the command number of this command
	      \$     if the effective UID is 0, a #, otherwise a $
	      \nnn   the character corresponding to the octal number nnn
	      \\     a backslash
	      \[     begin  a sequence of non-printing characters, which could be used to embed a
		     terminal control sequence into the prompt
	      \]     end a sequence of non-printing characters

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

READLINE
       This is the library that handles reading input when using an interactive shell, unless the
       --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.  Similarly, meta keys are denoted by M-key,
       so M-x means Meta-X.  (On keyboards without a meta key, M-x means ESC x, i.e.,  press  the
       Escape  key  then the x key.  This makes ESC the meta prefix.  The combination M-C-x means
       ESC-Control-x, or press the Escape key then hold the Control  key  while  pressing  the	x
       key.)

       Readline  commands  may	be given numeric arguments, which normally act as a repeat count.
       Sometimes, however, it is the sign of the argument that is significant.	Passing  a  nega-
       tive  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 devi-
       ates 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 $ indi-
       cate conditional constructs.  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 universal-argument.

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

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

   Readline Key Bindings
       The  syntax  for  controlling  key  bindings  in  the inputrc file is simple.  All that is
       required is the name of the command or the text of a macro and a key sequence to which  it
       should  be  bound.  The	name may be specified in one of two ways: as a symbolic key name,
       possibly with Meta- or Control- 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 modified  with	the  bind
       builtin	command.  The editing mode may be switched during interactive use by using the -o
       option to the set builtin command (see SHELL BUILTIN COMMANDS below).

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

	      set variable-name value

       Except  where  noted, readline variables can take the values On or Off.	The variables and
       their default values are:

       bell-style (audible)
	      Controls what happens when readline wants to ring the terminal  bell.   If  set  to
	      none,  readline  never  rings the bell.  If set to visible, readline uses a visible
	      bell if one is available.  If set to audible, readline attempts to ring the  termi-
	      nal's bell.
       comment-begin (``#'')
	      The  string  that is inserted when the readline insert-comment command is executed.
	      This command is bound to M-# in emacs mode and to # in vi command mode.
       completion-ignore-case (Off)
	      If set to On, readline performs filename matching and completion in a case-insensi-
	      tive fashion.
       completion-query-items (100)
	      This  determines when the user is queried about viewing the number of possible com-
	      pletions generated by the possible-completions command.  It may be set to any inte-
	      ger  value greater than or equal to zero.  If the number of possible completions is
	      greater than or equal to the value of this variable, the user is asked  whether  or
	      not he wishes to view them; otherwise they are simply listed on the terminal.
       convert-meta (On)
	      If  set to On, readline will convert characters with the eighth bit set to an ASCII
	      key sequence by stripping the eighth bit and  prefixing  an  escape  character  (in
	      effect, using escape as the meta prefix).
       disable-completion (Off)
	      If set to On, readline will inhibit word completion.  Completion characters will be
	      inserted into the line as if they had been mapped to self-insert.
       editing-mode (emacs)
	      Controls whether readline begins with a set of key bindings similar to emacs or vi.
	      editing-mode can be set to either emacs or vi.
       enable-keypad (Off)
	      When  set  to  On,  readline  will  try to enable the application keypad when it is
	      called.  Some systems need this to enable the arrow keys.
       expand-tilde (Off)
	      If set to on, tilde expansion is performed when readline attempts word completion.
       history-preserve-point
	      If set to on, the history code attempts to place point at the same location on each
	      history line retrived with previous-history 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 subse-
	      quently executing the character as a command.  If this variable has not been  given
	      a value, the characters ESC and C-J will terminate an incremental search.
       keymap (emacs)
	      Set  the	current  readline  keymap.   The  set  of  valid  keymap  names is emacs,
	      emacs-standard, emacs-meta, emacs-ctlx,  vi,  vi-command,  and  vi-insert.   vi  is
	      equivalent to vi-command; emacs is equivalent to emacs-standard.	The default value
	      is emacs; the value of editing-mode also affects the default keymap.
       mark-directories (On)
	      If set to On, completed directory names have a slash appended.
       mark-modified-lines (Off)
	      If set to On, history lines that have been modified are displayed with a	preceding
	      asterisk (*).
       mark-symlinked-directories (Off)
	      If  set to On, completed names which are symbolic links to directories 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 display 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 immedi-
	      ately instead of ringing the bell.
       visible-stats (Off)
	      If set to On, a character denoting a file's type as reported by stat(2) is appended
	      to the filename when listing possible completions.

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

       $if    The $if construct allows bindings to be made based on the editing mode, the  termi-
	      nal 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 com-
		     mand, 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, per-
		     haps to bind the key sequences output by the terminal's function keys.   The
		     word  on the right side of the = is tested against the both full name of the
		     terminal and the portion of the terminal name  before  the  first	-.   This
		     allows sun to match both sun and sun-cmd, for instance.

	      application
		     The  application construct is used to include application-specific settings.
		     Each 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  bind-
	      ings from that file.  For example, the following directive would read /etc/inputrc:

	      $include	/etc/inputrc

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

       Incremental searches begin before the user has finished typing the search string.  As each
       character of the search string is typed, readline displays the next entry from the history
       matching  the string typed so far.  An incremental search requires only as many characters
       as needed to find the desired history entry.  The characters present in the value  of  the
       isearch-terminators  variable  are used to terminate an incremental search.  If that vari-
       able 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 appro-
       priate.	This will search backward or forward in the history for the next  entry  matching
       the  search  string typed so far.  Any other key sequence bound to a readline command will
       terminate the search and execute that command.  For instance, a newline will terminate the
       search and accept the line, thereby executing the command from the history list.

       Readline  remembers the last incremental search string.	If two Control-Rs are typed with-
       out 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 con-
       tents of the current line.

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

   Commands for Moving
       beginning-of-line (C-a)
	      Move to the start of the current line.
       end-of-line (C-e)
	      Move to the end of the line.
       forward-char (C-f)
	      Move forward a character.
       backward-char (C-b)
	      Move back a character.
       forward-word (M-f)
	      Move forward to the end of the next word.  Words are composed of alphanumeric char-
	      acters (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 argu-
	      ment, 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-incre-
	      mental 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 sup-
	      plied 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.
       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 argu-
	      ment of each line in turn.
       shell-expand-line (M-C-e)
	      Expand  the  line  as the shell does.  This performs alias and history expansion as
	      well as all of the shell word  expansions.   See	HISTORY  EXPANSION  below  for	a
	      description of history 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  cur-
	      rent 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 com-
	      mands.  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 cursor is deleted.
       quoted-insert (C-q, C-v)
	      Add  the	next character typed to the line verbatim.  This is how to insert charac-
	      ters 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 argument, 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, characters bound
	      to self-insert replace the text at point rather than pushing the text to the right.
	      Characters bound to backward-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 back-
	      ward-word.
       unix-word-rubout (C-w)
	      Kill the word behind point, using white space as a word boundary.  The killed  text
	      is saved on the kill-ring.
       delete-horizontal-space (M-\)
	      Delete all spaces and tabs around point.
       kill-region
	      Kill the text in the current region.
       copy-region-as-kill
	      Copy the text in the region to the kill buffer.
       copy-backward-word
	      Copy the word before point to the kill buffer.  The word boundaries are the same as
	      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 following yank or yank-pop.

   Numeric Arguments
       digit-argument (M-0, M-1, ..., M--)
	      Add  this digit to the argument already accumulating, or start a new argument.  M--
	      starts a negative argument.
       universal-argument
	      This is another way to specify an argument.  If this command is followed by one  or
	      more  digits,  optionally  with a leading minus sign, those digits define the argu-
	      ment.  If the command is followed by  digits,  executing	universal-argument  again
	      ends  the  numeric  argument, but is otherwise ignored.  As a special case, if this
	      command is immediately followed by a character that is neither  a  digit	or  minus
	      sign,  the argument count for the next command is multiplied by four.  The argument
	      count is initially one, so executing this function the first time makes  the  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 $), username (if the  text
	      begins with ~), hostname (if the text begins with @), or command (including aliases
	      and functions) in turn.  If none of these produces a match, filename completion  is
	      attempted.
       possible-completions (M-?)
	      List the possible completions of the text before point.
       insert-completions (M-*)
	      Insert  all  completions of the text before point that would have been generated by
	      possible-completions.
       menu-complete
	      Similar to complete, but replaces the word to be completed with a single match from
	      the  list  of  possible  completions.   Repeated	execution  of menu-complete steps
	      through the list of possible completions, inserting each match in turn.  At the end
	      of the list of completions, the bell is rung (subject to the setting of bell-style)
	      and the original text is restored.  An argument of n moves n positions  forward  in
	      the  list  of matches; a negative argument may be used to move backward through the
	      list.  This command is intended to be bound to TAB, but is unbound by default.
       delete-char-or-list
	      Deletes the character under the cursor if not at the beginning or end of	the  line
	      (like  delete-char).   If  at  the  end  of the line, behaves identically to possi-
	      ble-completions.	This command is unbound by default.
       complete-filename (M-/)
	      Attempt filename completion on the text before point.
       possible-filename-completions (C-x /)
	      List the possible completions of the text before point, treating it as a filename.
       complete-username (M-~)
	      Attempt completion on the text before point, treating it as a username.
       possible-username-completions (C-x ~)
	      List the possible completions of the text before point, treating it as a username.
       complete-variable (M-$)
	      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.  Com-
	      mand 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 completions enclosed
	      within braces so the list is available to the shell (see Brace Expansion above).

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

   Miscellaneous
       re-read-init-file (C-x C-r)
	      Read in the contents of the inputrc file, and incorporate any bindings or  variable
	      assignments found there.
       abort (C-g)
	      Abort the current editing command and ring the terminal's bell (subject to the set-
	      ting 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 cor-
	      responding uppercase character.
       prefix-meta (ESC)
	      Metafy the next character typed.	ESC f is equivalent to Meta-f.
       undo (C-_, C-x C-u)
	      Incremental undo, separately remembered for each line.
       revert-line (M-r)
	      Undo all changes made to this line.  This is like executing the undo command enough
	      times to return the line to its initial state.
       tilde-expand (M-&)
	      Perform tilde expansion on the current word.
       set-mark (C-@, M-<space>)
	      Set the mark to the point.  If a numeric argument is supplied, the mark is  set  to
	      that position.
       exchange-point-and-mark (C-x C-x)
	      Swap  the  point	with  the  mark.  The current cursor position is set to the saved
	      position, and the old cursor position is saved as the mark.
       character-search (C-])
	      A character is read and point is moved to the next occurrence of that character.	A
	      negative count searches for previous occurrences.
       character-search-backward (M-C-])
	      A  character  is read and point is moved to the previous occurrence of that charac-
	      ter.  A negative count searches for subsequent occurrences.
       insert-comment (M-#)
	      Without a numeric argument, the value of the  readline  comment-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, otherwise the charac-
	      ters in comment-begin are deleted from the beginning of the line.  In either  case,
	      the  line  is  accepted  as if a newline had been typed.	The default value of com-
	      ment-begin causes this command to make the current line  a  shell  comment.   If	a
	      numeric  argument causes the comment character to be removed, the line will be exe-
	      cuted 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  dis-
	      played, 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	readline  output  stream.
	      If  a  numeric  argument is supplied, the output is formatted in such a way that it
	      can be made part of an inputrc file.
       dump-variables
	      Print all of the settable readline variables and their values to the readline  out-
	      put  stream.   If a numeric argument is supplied, the output is formatted in such a
	      way that it can be made part of an inputrc file.
       dump-macros
	      Print all of the readline key sequences bound to macros and the strings they ouput.
	      If  a  numeric  argument is supplied, the output is formatted in such a way that it
	      can be made part of an inputrc file.
       display-shell-version (C-x C-v)
	      Display version information about the current instance of bash.

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

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

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

       First, the actions specified by the compspec are used.  Only matches which are prefixed by
       the  word  being completed are returned.  When the -f or -d option is used for filename or
       directory name 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 considered.  The string is
       first split using the characters in the IFS special variable as delimiters.  Shell quoting
       is  honored.  Each word is then expanded using brace expansion, tilde expansion, parameter
       and variable expansion, command substitution, arithmetic expansion,  and  pathname  expan-
       sion, 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  per-
       formed; the function or command has complete freedom in generating the matches.

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

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

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

       Finally, any prefix and suffix specified with the -P and -S options are added to each mem-
       ber  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.

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

       When a compspec indicates that directory name completion is desired, the programmable com-
       pletion	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  vari-
       able  is  used  as the number of commands to save in a history list.  The text of the last
       HISTSIZE commands (default 500) is saved.  The shell stores each command  in  the  history
       list  prior  to	parameter  and variable expansion (see EXPANSION above) but after history
       expansion is performed, subject to the values of the shell variables HISTIGNORE and  HIST-
       CONTROL.

       On  startup,  the  history  is  initialized  from  the file named by the variable HISTFILE
       (default ~/.bash_history).  The file named by the value of HISTFILE is truncated, if  nec-
       essary,	to  contain  no more than the number of lines specified by the value of HISTFILE-
       SIZE.  When an interactive 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 overwritten.  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 HISTFILESIZE is not set, no
       truncation is performed.

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

       The shell allows control over which commands are saved on the history list.  The  HISTCON-
       TROL  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 command (see SHELL BUILTIN COMMANDS below).  Non-interactive shells do not perform
       history expansion by default.

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

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

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

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

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

       !      Start a history substitution, except when followed by a blank, newline, = or (.
       !n     Refer to command line n.
       !-n    Refer to the current command line minus n.
       !!     Refer to the previous command.  This is a synonym for `!-1'.
       !string
	      Refer to the most recent command starting with string.
       !?string[?]
	      Refer to the most recent command containing string.  The trailing ? may be  omitted
	      if string is followed immediately by a newline.
       ^string1^string2^
	      Quick  substitution.   Repeat  the  last	command,  replacing string1 with string2.
	      Equivalent to ``!!:s/string1/string2/'' (see Modifiers below).
       !#     The entire command line typed so far.

   Word Designators
       Word designators are used to select desired words from the event.  A : separates the event
       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 separated
       by single spaces.

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

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

   Modifiers
       After the optional word designator, there may appear a sequence of one or more of the fol-
       lowing 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 char-
	      acter of the event line.	The delimiter may be quoted in old and new with a  single
	      backslash.   If  &  appears in new, it is replaced by old.  A single backslash will
	      quote the &.  If old is null, it is set to the last old substituted, or, if no pre-
	      vious history substitutions took place, the last string in a !?string[?]	search.
       &      Repeat the previous substitution.
       g      Cause  changes  to be applied over the entire event line.  This is used in conjunc-
	      tion with `:s' (e.g., `:gs/old/new/') or `:&'.  If used with  `:s',  any	delimiter
	      can  be  used  in place of /, and the final delimiter is optional if it is the last
	      character of the event line.

SHELL BUILTIN COMMANDS
       Unless otherwise noted, each builtin command  documented  in  this  section  as	accepting
       options preceded by - accepts -- to signify the end of the options.
       : [arguments]
	      No  effect;  the command does nothing beyond expanding arguments and performing any
	      specified redirections.  A zero exit code is returned.

	.  filename [arguments]
       source filename [arguments]
	      Read and execute commands from filename in the current shell environment and return
	      the  exit  status of the last command executed from filename.  If filename does not
	      contain a slash, file names in PATH are used to find the directory containing 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  positional  parameters
	      when filename is executed.  Otherwise the positional parameters are unchanged.  The
	      return status is the status of the last command exited within the script (0  if  no
	      commands are executed), and false if filename is not found or cannot be read.

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

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

       bind [-m keymap] [-lpsvPSV]
       bind [-m keymap] [-q function] [-u function] [-r keyseq]
       bind [-m keymap] -f filename
       bind [-m keymap] -x keyseq:shell-command
       bind [-m keymap] keyseq:function-name
       bind readline-command
	      Display current readline key and function bindings, bind a key sequence to a  read-
	      line  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 sup-
	      plied, have the following meanings:
	      -m keymap
		     Use keymap as the keymap to be affected by the subsequent bindings.  Accept-
		     able  keymap  names  are  emacs, emacs-standard, emacs-meta, emacs-ctlx, vi,
		     vi-move, vi-command, and vi-insert.  vi is equivalent to  vi-command;  emacs
		     is equivalent to emacs-standard.
	      -l     List the names of all readline functions.
	      -p     Display  readline function names and bindings in such a way that they can be
		     re-read.
	      -P     List current readline function names and bindings.
	      -v     Display readline variable names and values in such a way that  they  can  be
		     re-read.
	      -V     List current readline variable names and values.
	      -s     Display  readline	key sequences bound to macros and the strings they output
		     in such a way that they can be re-read.
	      -S     Display readline key sequences bound to macros and the strings they output.
	      -f filename
		     Read key bindings from filename.
	      -q function
		     Query about which keys invoke the named function.
	      -u function
		     Unbind all keys bound to the named function.
	      -r keyseq
		     Remove any current binding for keyseq.
	      -x keyseq:shell-command
		     Cause shell-command to be executed whenever keyseq is entered.

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

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

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

       cd [-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.  Alterna-
	      tive 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 direc-
	      tory structure instead of following symbolic links (see also the -P option  to  the
	      set builtin command); the -L option forces symbolic links to be followed.  An argu-
	      ment of - is equivalent to $OLDPWD.  The return value is true if the directory  was
	      successfully changed; false otherwise.

       command [-pVv] command [arg ...]
	      Run  command  with  args suppressing the normal shell function lookup. Only builtin
	      commands or commands found in the PATH are executed.  If the -p  option  is  given,
	      the  search for command is performed using a default value for PATH that is guaran-
	      teed to find all of the standard utilities.  If either the -V or -v option is  sup-
	      plied,  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 sup-
	      plied  and  an  error  occurred or command cannot be found, the exit status is 127.
	      Otherwise, the exit status of the command builtin is the exit status of command.

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

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

	      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  pre-
       fix] [-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 sup-
	      plied, or if no  options	are  supplied,	existing  completion  specifications  are
	      printed  in  a way that allows them to be reused as input.  The -r option removes a
	      completion specification for each name, or, if no names are supplied,  all  comple-
	      tion specifications.

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

	      Other options, if specified, have the following meanings.  The arguments to the -G,
	      -W,  and	-X options (and, if necessary, the -P and -S options) should be quoted to
	      protect them from expansion before the complete builtin is invoked.
	      -o comp-option
		      The comp-option controls several aspects of the compspec's behavior  beyond
		      the simple generation of completions.  comp-option may be one of:
		      default Use  readline's  default filename completion if the compspec gener-
			      ates no matches.
		      dirnames
			      Perform directory name completion  if  the  compspec  generates  no
			      matches.
		      filenames
			      Tell readline that the compspec generates filenames, so it can per-
			      form 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  com-
			      pleted at the end of the line.
	      -A action
		      The  action may be one of the following to generate a list of possible com-
		      pletions:
		      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 specified 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 completed.
	      -C command
		      command is executed in a subshell environment, and its output  is  used  as
		      the possible completions.
	      -F function
		      The  shell  function function is executed in the current shell environment.
		      When it finishes, the possible completions are retrieved from the value  of
		      the COMPREPLY array variable.
	      -X filterpat
		      filterpat  is  a	pattern as used for filename expansion.  It is applied to
		      the list of possible completions generated by  the  preceding  options  and
		      arguments, and each 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 completion after all
		      other options have been applied.
	      -S suffix
		      suffix is appended to each possible completion after all other options have
		      been applied.

	      The return value is true unless an invalid option is supplied, an option other than
	      -p or -r is supplied without a name argument, an attempt is made to remove  a  com-
	      pletion  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.  The -F option implies -f.  The  following  options	can  be  used  to
	      restrict	output	to  variables  with  the specified attribute or to give variables
	      attributes:
	      -a     Each name is an array variable (see Arrays above).
	      -f     Use function names only.
	      -i     The variable is treated as an integer; arithmetic evaluation (see ARITHMETIC
		     EVALUATION ) is performed when the variable is assigned a value.
	      -r     Make  names  readonly.  These names cannot then be assigned values by subse-
		     quent assignment statements or unset.
	      -t     Give each name the trace attribute.  Traced functions inherit the DEBUG trap
		     from  the	calling  shell.   The  trace attribute has no special meaning for
		     variables.
	      -x     Mark names for export to subsequent commands via the environment.

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

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

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

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

       echo [-neE] [arg ...]
	      Output  the args, separated by spaces, followed by a newline.  The return status is
	      always 0.  If -n is specified, the trailing  newline  is	suppressed.   If  the  -e
	      option  is  given,  interpretation of the following backslash-escaped characters is
	      enabled.	The -E option disables the interpretation  of  these  escape  characters,
	      even  on	systems where they are interpreted by default.	The xpg_echo shell option
	      may be used to dynamically determine whether or not echo expands these escape char-
	      acters  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 com-
	      mand 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  com-
	      mand  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  argu-
	      ments  are  given,  or  if  the  -p option is supplied, a list of shell builtins is
	      printed.	With no other option arguments, the list consists of  all  enabled  shell
	      builtins.   If  -n  is supplied, only disabled builtins are printed.  If -a is sup-
	      plied, the list printed includes all builtins, with an indication of whether or not
	      each  is enabled.  If -s is supplied, the output is restricted to the POSIX special
	      builtins.  The return value is 0 unless a name is not a shell builtin or	there  is
	      an error loading a new builtin from a shared object.

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

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

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

       export [-fn] [name[=word]] ...
       export -p
	      The supplied names are marked for automatic export to  the  environment  of  subse-
	      quently  executed  commands.   If  the -f option is given, the names refer to func-
	      tions.  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 prop-
	      erty to be removed from the named variables.  export returns an exit  status  of	0
	      unless  an  invalid  option  is  encountered, one of the names is not a valid shell
	      variable name, or -f is supplied with a name that is not a function.

       fc [-e ename] [-nlr] [first] [last]
       fc -s [pat=rep] [cmd]
	      Fix Command.  In the first form, a range of commands from first to last is selected
	      from  the history list.  First and last may be specified as a string (to locate the
	      last command 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 current command num-
	      ber).  If last is not specified it is set to the current command	for  listing  (so
	      that  ``fc  -l -10'' prints the last 10 commands) and to first otherwise.  If first
	      is not specified it is set to the previous command for editing and -16 for listing.

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

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

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

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

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

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

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

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

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

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

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

       hash [-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 sup-
	      plied,  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 format 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 numbers.  Lines  listed
	      with  a  *  have	been modified.	An argument of n lists only the last n lines.  If
	      filename is supplied, it is used as the name of the history file; if not, the value
	      of HISTFILE is used.  Options, if supplied, have the following meanings:
	      -c     Clear the history list by deleting all the entries.
	      -d offset
		     Delete the history entry at position offset.
	      -a     Append  the ``new'' history lines (history lines entered since the beginning
		     of the current bash session) to the history file.
	      -n     Read the history lines not already read from the history file into the  cur-
		     rent  history  list.  These are lines appended to the history file since the
		     beginning of the current bash session.
	      -r     Read the contents of the history file and use them as the current history.
	      -w     Write the current history to  the	history  file,	overwriting  the  history
		     file's contents.
	      -p     Perform history substitution on the following args and display the result on
		     the standard output.  Does not store the results in the history list.   Each
		     arg must be quoted to disable normal history expansion.
	      -s     Store  the  args in the history list as a single entry.  The last command in
		     the history list is removed before the args are added.

	      The return value is 0 unless an invalid option  is  encountered,	an  error  occurs
	      while  reading  or  writing  the	history file, an invalid offset is supplied as an
	      argument to -d, or the history expansion supplied as an argument to -p fails.

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

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

	      If  the  -x  option is supplied, jobs replaces any jobspec found in command or args
	      with the 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 job-
	      spec.  sigspec is either a signal name such as SIGKILL or a signal  number;  signum
	      is  a  signal  number.   If sigspec is a signal name, the name may be given with or
	      without the SIG prefix.  If sigspec is not present, then SIGTERM	is  assumed.   An
	      argument	of  -l	lists the signal names.  If any 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  ARITHMETIC  EVALUATION).
	      If the last arg evaluates to 0, let returns 1; 0 is returned otherwise.

       local [option] [name[=value] ...]
	      For each argument, a local variable named name is created, and assigned value.  The
	      option can be any of the options accepted by declare.  When local is used within	a
	      function,  it  causes  the variable name to have a visible scope restricted to that
	      function and its children.  With no operands, local writes a list  of  local  vari-
	      ables  to the standard output.  It is an error to use local when not within a func-
	      tion.  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 following 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 sta-
	      tus  is  0.   popd returns false if an invalid option is encountered, the directory
	      stack is empty, a non-existent directory stack entry is specified, or the directory
	      change fails.

       printf format [arguments]
	      Write  the formatted arguments to the standard output under the control of the for-
	      mat.  The format is a character string which contains three types of objects: plain
	      characters, which are simply copied to standard output, character escape sequences,
	      which are converted and copied to the standard output, and  format  specifications,
	      each  of which causes printing of the next successive argument.  In addition to the
	      standard printf(1) formats, %b causes printf to expand backslash	escape	sequences
	      in  the  corresponding  argument,  and %q causes printf to output the corresponding
	      argument in a format that can be reused as shell input.

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

       pushd [-n] [dir]
       pushd [-n] [+n] [-n]
	      Adds  a  directory  to the top of the directory stack, or rotates the stack, making
	      the new top of the  stack  the  current  working	directory.   With  no  arguments,
	      exchanges  the  top  two	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 work-
		     ing 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 directory stack is empty, a non-existent directory stack  ele-
	      ment  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 inter-
	      vening  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 following 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 com-
		     plete line of input.
	      -p prompt
		     Display prompt  on  standard  error,  without  a  trailing  newline,  before
		     attempting to read any input.  The prompt is displayed only if input is com-
		     ing from a terminal.
	      -r     Backslash does not act as an escape character.  The backslash is  considered
		     to  be part of the line.  In particular, a backslash-newline pair may not be
		     used as a line continuation.
	      -s     Silent mode.  If input is coming from a terminal, characters are not echoed.
	      -t timeout
		     Cause read to time out and return failure if a complete line of input is not
		     read within timeout seconds.  This option has no effect if read is not read-
		     ing 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  variable  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 ...]
	      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 correspond-
	      ing to the names are so marked.  The -a option restricts the variables  to  arrays.
	      If  no  name  arguments  are  given, or if the -p option is supplied, a list of all
	      readonly names is printed.  The -p option causes output to be displayed in a format
	      that  may  be  reused as input.  The return status is 0 unless an invalid option is
	      encountered, one of the names is not a valid shell variable name, or -f is supplied
	      with a name that is not a function.

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

       set [--abefhkmnptuvxBCHP] [-o option] [arg ...]
	      Without  options, the name and value of each shell variable are displayed in a for-
	      mat that can be reused as input.	The output is sorted  according  to  the  current
	      locale.  When options are specified, they set or unset shell attributes.	Any argu-
	      ments remaining after the options are processed are treated as values for the posi-
	      tional  parameters  and  are  assigned,  in order, to $1, $2, ...  $n.  Options, if
	      specified, have the following meanings:
	      -a      Automatically mark variables and functions which are  modified  or  created
		      for export to the environment of subsequent commands.
	      -b      Report  the  status  of terminated background jobs immediately, rather than
		      before the next primary prompt.  This is effective only when job control is
		      enabled.
	      -e      Exit immediately if a simple command (see SHELL GRAMMAR above) exits with a
		      non-zero status.	The shell does not exit if the command that fails is part
		      of  an  until  or  while	loop, part of an if statement, part of a && or ||
		      list, or if the command's return value is being inverted via !.  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  envi-
		      ronment for a command, not just those that precede the command name.
	      -m      Monitor  mode.   Job  control is enabled.  This option is on by default for
		      interactive shells on systems that support  it  (see  JOB  CONTROL  above).
		      Background  processes run in a separate process group and a line containing
		      their exit status is printed upon their completion.
	      -n      Read commands but do not execute them.  This may be used to check  a  shell
		      script for syntax errors.  This is ignored by interactive shells.
	      -o option-name
		      The option-name can be one of the following:
		      allexport
			      Same as -a.
		      braceexpand
			      Same as -B.
		      emacs   Use an emacs-style command line editing interface.  This is enabled
			      by default when the shell  is  interactive,  unless  the	shell  is
			      started with the --noediting option.
		      errexit Same as -e.
		      hashall Same as -h.
		      histexpand
			      Same as -H.
		      history Enable  command  history,  as  described above under HISTORY.  This
			      option is on by default in interactive shells.
		      ignoreeof
			      The effect is as if the shell  command  ``IGNOREEOF=10''	had  been
			      executed (see Shell Variables above).
		      keyword Same as -k.
		      monitor Same as -m.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.  nolog Currently ignored.
		      notify  Same as -b.
		      nounset Same as -u.
		      onecmd  Same as -t.
		      physical
			      Same as -P.
		      posix   Change  the  behavior  of  bash where the default operation differs
			      from the POSIX 1003.2 standard to match the standard (posix mode).
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      vi      Use a vi-style command line editing interface.
		      xtrace  Same as -x.
		      If -o is supplied with no option-name, the values of  the  current  options
		      are  printed.   If +o is supplied with no option-name, a series of set com-
		      mands 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 parameter expansion.  If
		      expansion is attempted on an unset variable, the shell prints an error mes-
		      sage, and, if not interactive, exits with a non-zero status.
	      -v      Print shell input lines as they are read.
	      -x      After  expanding	each  simple  command, display the expanded value of PS4,
		      followed by the command and its expanded arguments.
	      -B      The shell performs brace expansion (see Brace Expansion above).  This is on
		      by default.
	      -C      If set, bash does not overwrite an existing file with the >, >&, and <> re-
		      direction operators.  This may be overridden when creating output files  by
		      using the redirection operator >| instead of >.
	      -H      Enable  !   style  history substitution.	This option is on by default when
		      the shell is interactive.
	      -P      If set, the shell does not follow symbolic links	when  executing  commands
		      such as cd that change the current working directory.  It uses the physical
		      directory structure instead.  By default, bash follows the logical chain of
		      directories when performing commands which change the current directory.
	      --      If  no  arguments  follow  this  option, then the positional parameters are
		      unset.  Otherwise, the positional parameters are set to the args,  even  if
		      some of them begin with a -.
	      -       Signal  the  end of options, cause all remaining args to be assigned to the
		      positional parameters.  The -x and -v options are turned off.  If there are
		      no args, the positional 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  argu-
	      ments  to  an  invocation of the shell.  The current set of options may be found in
	      $-.  The return status is always true unless an invalid option is encountered.

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

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

	      The  return  status  when listing options is zero if all optnames are enabled, non-
	      zero 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 component in a cd com-
		      mand will be corrected.  The errors checked for are transposed  characters,
		      a missing character, and one character too many.	If a correction is found,
		      the corrected file name is printed, and the command proceeds.  This  option
		      is only used by interactive shells.
	      checkhash
		      If  set,	bash  checks that a command found in the hash table exists before
		      trying to execute it.  If a hashed command no longer exists, a normal  path
		      search is performed.
	      checkwinsize
		      If  set,	bash checks the window size after each command and, if necessary,
		      updates the values of LINES and COLUMNS.
	      cmdhist If set, bash attempts to save all lines of a multiple-line command  in  the
		      same history entry.  This allows easy re-editing of multi-line commands.
	      dotglob If  set,	bash  includes	filenames  beginning with a `.' in the results of
		      pathname expansion.
	      execfail
		      If set, a non-interactive shell will not exit if it cannot execute the file
		      specified as an argument to the exec builtin command.  An interactive shell
		      does not exit if exec fails.
	      expand_aliases
		      If set, aliases are expanded as described above under ALIASES.  This option
		      is enabled by default for interactive shells.
	      extglob If  set, the extended pattern matching features described above under Path-
		      name Expansion are enabled.
	      histappend
		      If set, the history list is appended to the file named by the value of  the
		      HISTFILE variable when the shell exits, rather than overwriting the file.
	      histreedit
		      If  set, and readline is being used, a user is given the opportunity to re-
		      edit a failed history substitution.
	      histverify
		      If set, and readline is being used, the results of history substitution are
		      not immediately passed to the shell parser.  Instead, the resulting line is
		      loaded into the readline editing buffer, allowing further modification.
	      hostcomplete
		      If set, and readline is being used, bash will attempt to	perform  hostname
		      completion  when	a  word containing a @ is being completed (see Completing
		      under READLINE above).  This is enabled by default.
	      huponexit
		      If set, bash will send SIGHUP to all jobs when an interactive  login  shell
		      exits.
	      interactive_comments
		      If  set, allow a word beginning with # to cause that word and all remaining
		      characters on that line to be ignored in an interactive shell (see COMMENTS
		      above).  This option is enabled by default.
	      lithist If set, and the cmdhist option is enabled, multi-line commands are saved to
		      the 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 INVOCA-
		      TION 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 displayed.
	      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  perform-
		      ing pathname expansion (see Pathname Expansion above).
	      nullglob
		      If  set,	bash allows patterns which match no files (see Pathname Expansion
		      above) to expand to a null string, rather than themselves.
	      progcomp
		      If set, the programmable completion facilities (see Programmable Completion
		      above) are enabled.  This option is enabled by default.
	      promptvars
		      If set, prompt strings undergo variable and parameter expansion after being
		      expanded as described in	PROMPTING  above.   This  option  is  enabled  by
		      default.
	      restricted_shell
		      The  shell  sets	this  option  if  it  is  started in restricted mode (see
		      RESTRICTED SHELL below).	The value may not be changed.  This is not  reset
		      when the startup files are executed, allowing the startup files to discover
		      whether or not a shell is restricted.
	      shift_verbose
		      If set, the shift builtin prints an error  message  when	the  shift  count
		      exceeds the number of positional parameters.
	      sourcepath
		      If set, the source (.) builtin uses the value of PATH to find the directory
		      containing the file supplied as an argument.  This  option  is  enabled  by
		      default.
	      xpg_echo
		      If set, the echo builtin expands backslash-escape sequences by default.
       suspend [-f]
	      Suspend  the  execution  of  this shell until it receives a SIGCONT signal.  The -f
	      option says not to complain if this is a login shell;  just  suspend  anyway.   The
	      return  status is 0 unless the shell is a login shell and -f is not supplied, or if
	      job control is not enabled.
       test expr
       [ expr ]
	      Return a status of 0 or 1 depending on the evaluation of the conditional expression
	      expr.  Each operator and operand must be a separate argument.  Expressions are com-
	      posed of the primaries described above under CONDITIONAL EXPRESSIONS.

	      Expressions may be combined using the following  operators,  listed  in  decreasing
	      order of precedence.
	      ! expr True if expr is false.
	      ( expr )
		     Returns  the  value of expr.  This may be used to override the normal prece-
		     dence 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  num-
	      ber 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  con-
		     ditional operator, the expression is false.
	      3 arguments
		     If  the  second  argument	is one of the binary conditional operators listed
		     above under CONDITIONAL EXPRESSIONS, the result of  the  expression  is  the
		     result  of  the binary test using the first and third arguments as operands.
		     If the first argument is !, the value is the negation  of	the  two-argument
		     test using the second and third arguments.  If the first argument is exactly
		     ( and the third argument is exactly ), the result is the  one-argument  test
		     of  the second argument.  Otherwise, the expression is false.  The -a and -o
		     operators are considered binary operators in this case.
	      4 arguments
		     If the first argument is !, the result is the negation of the three-argument
		     expression  composed  of the remaining arguments.	Otherwise, the expression
		     is parsed and evaluated according	to  precedence	using  the  rules  listed
		     above.
	      5 or more arguments
		     The  expression  is  parsed  and evaluated according to precedence using the
		     rules listed above.

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

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

       type [-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,  key-
	      word,  function,	builtin,  or file if name is an alias, shell reserved word, func-
	      tion, 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
	      specified  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
	      function lookup, as with the command builtin.  type returns  true  if  any  of  the
	      arguments are found, false if none are found.

       ulimit [-SHacdflmnpstuv [limit]]
	      Provides control over the resources available to the shell and to processes started
	      by it, on systems that allow such control.  The -H and -S options specify that  the
	      hard or soft limit is set for the given resource.  A hard limit cannot be increased
	      once it is set; a soft limit may be increased up to the value of	the  hard  limit.
	      If  neither  -H  nor  -S	is specified, both the soft and hard limits are set.  The
	      value of limit can be a number in the unit specified for the resource or one of the
	      special  values  hard,  soft, or unlimited, which stand for the current hard limit,
	      the current soft limit, and no limit, respectively.  If limit is omitted, the  cur-
	      rent  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 follows:
	      -a     All current limits are reported
	      -c     The maximum size of core files created
	      -d     The maximum size of a process's data segment
	      -f     The maximum size of files created by the shell
	      -l     The maximum size that may be locked into memory
	      -m     The maximum resident set size
	      -n     The  maximum number of open file descriptors (most systems do not allow this
		     value to be set)
	      -p     The pipe size in 512-byte blocks (this may not be set)
	      -s     The maximum stack size
	      -t     The maximum amount of cpu time in seconds
	      -u     The maximum number of processes available to a single user
	      -v     The maximum amount of virtual memory available to the shell

	      If limit is given, it is the new value of the specified resource (the -a option  is
	      display only).  If no option is given, then -f is assumed.  Values are in 1024-byte
	      increments, except for -t, which is in seconds, -p, which is in units  of  512-byte
	      blocks, and -n and -u, which are unscaled values.  The return status is 0 unless an
	      invalid option 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 symbolic form; the
	      default output is an octal number.  If the -p option is supplied, and mode is omit-
	      ted, the output is in a form that may be reused as input.  The return status  is	0
	      if the mode was successfully changed or if no mode argument was supplied, and false
	      otherwise.

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

       unset [-fv] [name ...]
	      For each name, remove the corresponding variable or function.  If  no  options  are
	      supplied,  or  the -v option is given, each name refers to a shell variable.  Read-
	      only variables may not be unset.	If -f is specifed, each name refers  to  a  shell
	      function,  and the function definition is removed.  Each unset variable or function
	      is removed from the environment passed to subsequent 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 status  is  true
	      unless a name does not exist or is readonly.

       wait [n]
	      Wait  for  the  specified  process  and  return its termination status.  n may be a
	      process ID or a job specification; if a job spec is given, all  processes  in  that
	      job's  pipeline are waited for.  If n is not given, all currently active child pro-
	      cesses are waited for, and the return status is zero.  If n specifies  a	non-exis-
	      tent 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 con-
       trolled than the standard shell.  It behaves identically to bash with the  exception  that
       the following are disallowed or not performed:

       o      changing directories with cd

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

       o      specifying command names containing /

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

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

       o      importing function definitions from the shell environment at startup

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

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

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

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

       o      Using the enable builtin command to enable disabled shell builtins

       o      specifying the -p option to the command builtin command

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

       These restrictions are enforced after any startup files are read.

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

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

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

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

       Chet Ramey, Case Western Reserve University
       chet@ins.CWRU.Edu

BUG REPORTS
       If you find a bug in bash, you should report it.  But first, you should make sure that  it
       really is a bug, and that it appears in the latest version of bash that you have.

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

       ALL bug reports should include:

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

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

       Comments   and	bug   reports	concerning   this  manual  page  should  be  directed  to
       chet@ins.CWRU.Edu.

BUGS
       It's too big and too slow.

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

       Aliases are confusing in some uses.

       Shell builtin commands and functions are not stoppable/restartable.

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

       Commands inside of $(...) command  substitution	are  not  parsed  until  substitution  is
       attempted.  This will delay error reporting until some time after the command is entered.

       Array variables may not (yet) be exported.

GNU Bash-2.05b				   2002 July 15 				  BASH(1)


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