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BASH(1) 										  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).

       --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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