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-\input texinfo.tex @c -*- texinfo -*-
-@c %**start of header
-@setfilename bashref.info
-@settitle Bash Reference Manual
-@c %**end of header
-
-@setchapternewpage odd
-
-@include version.texi
-
-@copying
-This text is a brief description of the features that are present in
-the Bash shell (version @value{VERSION}, @value{UPDATED}).
-
-This is Edition @value{EDITION}, last updated @value{UPDATED},
-of @cite{The GNU Bash Reference Manual},
-for @code{Bash}, Version @value{VERSION}.
-
-Copyright @copyright{} 1988-2004 Free Software Foundation, Inc.
-
-Permission is granted to make and distribute verbatim copies of
-this manual provided the copyright notice and this permission notice
-are preserved on all copies.
-
-@quotation
-Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with no
-Invariant Sections, with the Front-Cover texts being ``A GNU Manual,''
-and with the Back-Cover Texts as in (a) below.  A copy of the license is
-included in the section entitled ``GNU Free Documentation License.''
-
-(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
-this GNU Manual, like GNU software.  Copies published by the Free
-Software Foundation raise funds for GNU development.''
-@end quotation
-@end copying
-
-@defcodeindex bt
-@defcodeindex rw
-@set BashFeatures
-
-@dircategory Basics
-@direntry
-* Bash: (bash).                     The GNU Bourne-Again SHell.
-@end direntry
-
-@finalout
-
-@titlepage
-@title Bash Reference Manual
-@subtitle Reference Documentation for Bash
-@subtitle Edition @value{EDITION}, for @code{Bash} Version @value{VERSION}.
-@subtitle @value{UPDATED-MONTH}
-@author Chet Ramey, Case Western Reserve University
-@author Brian Fox, Free Software Foundation
-
-@page
-@vskip 0pt plus 1filll
-@insertcopying
-
-@sp 1
-Published by the Free Software Foundation @*
-59 Temple Place, Suite 330, @*
-Boston, MA 02111-1307 @*
-USA @*
-
-@end titlepage
-
-@contents
-
-@ifnottex
-@node Top, Introduction, (dir), (dir)
-@top Bash Features
-
-This text is a brief description of the features that are present in
-the Bash shell (version @value{VERSION}, @value{UPDATED})..
-
-This is Edition @value{EDITION}, last updated @value{UPDATED},
-of @cite{The GNU Bash Reference Manual},
-for @code{Bash}, Version @value{VERSION}.
-
-Bash contains features that appear in other popular shells, and some
-features that only appear in Bash.  Some of the shells that Bash has
-borrowed concepts from are the Bourne Shell (@file{sh}), the Korn Shell
-(@file{ksh}), and the C-shell (@file{csh} and its successor,
-@file{tcsh}). The following menu breaks the features up into
-categories based upon which one of these other shells inspired the
-feature.
-
-This manual is meant as a brief introduction to features found in
-Bash.  The Bash manual page should be used as the definitive
-reference on shell behavior.
-
-@menu
-* Introduction::		An introduction to the shell.
-
-* Definitions::			Some definitions used in the rest of this
-				manual.
-
-* Basic Shell Features::	The shell "building blocks".
-
-* Shell Builtin Commands::	Commands that are a part of the shell.
-
-* Shell Variables::		Variables used or set by Bash.
-
-* Bash Features::		Features found only in Bash.
-
-* Job Control::			A chapter describing what job control is
-				and how Bash allows you to use it.
-
-* Using History Interactively::	Chapter dealing with history expansion
-				rules.
-
-* Command Line Editing::	Chapter describing the command line
-				editing features.
-
-* Installing Bash::		How to build and install Bash on your system.
-
-* Reporting Bugs::		How to report bugs in Bash.
-
-* Major Differences From The Bourne Shell::	A terse list of the differences
-						between Bash and historical
-						versions of /bin/sh.
-
-* Copying This Manual::		Copying this manual.
-
-* Builtin Index::		Index of Bash builtin commands.
-
-* Reserved Word Index::		Index of Bash reserved words.
-
-* Variable Index::		Quick reference helps you find the
-				variable you want.
-
-* Function Index::		Index of bindable Readline functions.
-
-* Concept Index::		General index for concepts described in
-				this manual.
-@end menu
-@end ifnottex
-
-@node Introduction
-@chapter Introduction
-@menu
-* What is Bash?::		A short description of Bash.
-
-* What is a shell?::		A brief introduction to shells.
-@end menu
-
-@node What is Bash?
-@section What is Bash?
-
-Bash is the shell, or command language interpreter,
-for the @sc{gnu} operating system.
-The name is an acronym for the @samp{Bourne-Again SHell},
-a pun on Stephen Bourne, the author of the direct ancestor of
-the current Unix shell @code{sh}, 
-which appeared in the Seventh Edition Bell Labs Research version
-of Unix.
-
-Bash is largely compatible with @code{sh} and incorporates useful
-features from the Korn shell @code{ksh} and the C shell @code{csh}.
-It is intended to be a conformant implementation of the @sc{ieee}
-@sc{posix} Shell and Tools specification (@sc{ieee} Working Group 1003.2).
-It offers functional improvements over @code{sh} for both interactive and
-programming use.
-
-While the @sc{gnu} operating system provides other shells, including
-a version of @code{csh}, Bash is the default shell.
-Like other @sc{gnu} software, Bash is quite portable.  It currently runs
-on nearly every version of Unix and a few other operating systems @minus{}
-independently-supported ports exist for @sc{ms-dos}, @sc{os/2},
-and Windows platforms.
-
-@node What is a shell?
-@section What is a shell?
-
-At its base, a shell is simply a macro processor that executes
-commands.  The term macro processor means functionality where text
-and symbols are expanded to create larger expressions.
-
-A Unix shell is both a command interpreter and a programming
-language.  As a command interpreter, the shell provides the user
-interface to the rich set of @sc{gnu} utilities.  The programming
-language features allow these utilitites to be combined.
-Files containing commands can be created, and become
-commands themselves.  These new commands have the same status as
-system commands in directories such as @file{/bin}, allowing users
-or groups to establish custom environments to automate their common
-tasks.
-
-Shells may be used interactively or non-interactively.  In
-interactive mode, they accept input typed from the keyboard.
-When executing non-interactively, shells execute commands read
-from a file.
-
-A shell allows execution of @sc{gnu} commands, both synchronously and
-asynchronously.
-The shell waits for synchronous commands to complete before accepting
-more input; asynchronous commands continue to execute in parallel
-with the shell while it reads and executes additional commands.
-The @dfn{redirection} constructs permit
-fine-grained control of the input and output of those commands.
-Moreover, the shell allows control over the contents of commands'
-environments.
-
-Shells also provide a small set of built-in
-commands (@dfn{builtins}) implementing functionality impossible
-or inconvenient to obtain via separate utilities.
-For example, @code{cd}, @code{break}, @code{continue}, and
-@code{exec}) cannot be implemented outside of the shell because
-they directly manipulate the shell itself.
-The @code{history}, @code{getopts}, @code{kill}, or @code{pwd}
-builtins, among others, could be implemented in separate utilities,
-but they are more convenient to use as builtin commands.
-All of the shell builtins are described in
-subsequent sections.
-
-While executing commands is essential, most of the power (and
-complexity) of shells is due to their embedded programming
-languages.  Like any high-level language, the shell provides
-variables, flow control constructs, quoting, and functions. 
-
-Shells offer features geared specifically for
-interactive use rather than to augment the programming language. 
-These interactive features include job control, command line
-editing, command history and aliases.  Each of these features is
-described in this manual.
-
-@node Definitions
-@chapter Definitions
-These definitions are used throughout the remainder of this manual.
-
-@table @code
-
-@item POSIX
-@cindex POSIX
-A family of open system standards based on Unix.  Bash
-is concerned with @sc{posix} 1003.2, the Shell and Tools Standard.
-
-@item blank
-A space or tab character.
-
-@item builtin
-@cindex builtin
-A command that is implemented internally by the shell itself, rather
-than by an executable program somewhere in the file system.
-
-@item control operator
-@cindex control operator
-A @code{word} that performs a control function.  It is a @code{newline}
-or one of the following:
-@samp{||}, @samp{&&}, @samp{&}, @samp{;}, @samp{;;},
-@samp{|}, @samp{(}, or @samp{)}.
-
-@item exit status
-@cindex exit status
-The value returned by a command to its caller.  The value is restricted
-to eight bits, so the maximum value is 255.
-
-@item field
-@cindex field
-A unit of text that is the result of one of the shell expansions.  After
-expansion, when executing a command, the resulting fields are used as
-the command name and arguments.
-
-@item filename
-@cindex filename
-A string of characters used to identify a file.
-
-@item job
-@cindex job
-A set of processes comprising a pipeline, and any processes descended
-from it, that are all in the same process group.
-
-@item job control
-@cindex job control
-A mechanism by which users can selectively stop (suspend) and restart
-(resume) execution of processes.
-
-@item metacharacter
-@cindex metacharacter
-A character that, when unquoted, separates words.  A metacharacter is
-a @code{blank} or one of the following characters:
-@samp{|}, @samp{&}, @samp{;}, @samp{(}, @samp{)}, @samp{<}, or
-@samp{>}.
-
-@item name
-@cindex name
-@cindex identifier
-A @code{word} consisting solely of letters, numbers, and underscores,
-and beginning with a letter or underscore.  @code{Name}s are used as
-shell variable and function names.
-Also referred to as an @code{identifier}.
-
-@item operator
-@cindex operator, shell
-A @code{control operator} or a @code{redirection operator}.
-@xref{Redirections}, for a list of redirection operators.
-
-@item process group
-@cindex process group
-A collection of related processes each having the same process
-group @sc{id}.
-
-@item process group ID
-@cindex process group ID
-A unique identifer that represents a @code{process group}
-during its lifetime.
-
-@item reserved word
-@cindex reserved word
-A @code{word} that has a special meaning to the shell.  Most reserved
-words introduce shell flow control constructs, such as @code{for} and
-@code{while}.
-
-@item return status
-@cindex return status
-A synonym for @code{exit status}.
-
-@item signal
-@cindex signal
-A mechanism by which a process may be notified by the kernel
-of an event occurring in the system.
-
-@item special builtin
-@cindex special builtin
-A shell builtin command that has been classified as special by the
-@sc{posix} 1003.2 standard.
-
-@item token
-@cindex token
-A sequence of characters considered a single unit by the shell.  It is
-either a @code{word} or an @code{operator}.
-
-@item word
-@cindex word
-A @code{token} that is not an @code{operator}.
-@end table
-
-@node Basic Shell Features
-@chapter Basic Shell Features
-@cindex Bourne shell
-
-Bash is an acronym for @samp{Bourne-Again SHell}.
-The Bourne shell is
-the traditional Unix shell originally written by Stephen Bourne.
-All of the Bourne shell builtin commands are available in Bash,
-The rules for evaluation and quoting are taken from the @sc{posix}
-specification for the `standard' Unix shell.
-
-This chapter briefly summarizes the shell's `building blocks':
-commands, control structures, shell functions, shell @i{parameters},
-shell expansions,
-@i{redirections}, which are a way to direct input and output from
-and to named files, and how the shell executes commands.
-
-@menu
-* Shell Syntax::		What your input means to the shell.
-* Shell Commands::		The types of commands you can use.
-* Shell Functions::		Grouping commands by name.
-* Shell Parameters::		How the shell stores values.
-* Shell Expansions::		How Bash expands parameters and the various
-				expansions available.
-* Redirections::		A way to control where input and output go.
-* Executing Commands::		What happens when you run a command.
-* Shell Scripts::		Executing files of shell commands.
-@end menu
-
-@node Shell Syntax
-@section Shell Syntax
-@menu
-* Shell Operation::	The basic operation of the shell.
-
-* Quoting::		How to remove the special meaning from characters.
-
-* Comments::		How to specify comments.
-@end menu
-
-When the shell reads input, it proceeds through a
-sequence of operations.  If the input indicates the beginning of a
-comment, the shell ignores the comment symbol (@samp{#}), and the rest
-of that line.
-                                
-Otherwise, roughly speaking,  the shell reads its input and
-divides the input into words and operators, employing the quoting rules
-to select which meanings to assign various words and characters.
-
-The shell then parses these tokens into commands and other constructs,
-removes the special meaning of certain words or characters, expands
-others, redirects input and output as needed, executes the specified
-command, waits for the command's exit status, and makes that exit status
-available for further inspection or processing.
-
-@node Shell Operation
-@subsection Shell Operation
-
-The following is a brief description of the shell's operation when it
-reads and executes a command.  Basically, the shell does the
-following:
-
-@enumerate
-@item
-Reads its input from a file (@pxref{Shell Scripts}), from a string
-supplied as an argument to the @option{-c} invocation option
-(@pxref{Invoking Bash}), or from the user's terminal.
-
-@item
-Breaks the input into words and operators, obeying the quoting rules
-described in @ref{Quoting}.  These tokens are separated by
-@code{metacharacters}.  Alias expansion is performed by this step
-(@pxref{Aliases}).
-
-@item
-Parses the tokens into simple and compound commands
-(@pxref{Shell Commands}).
-
-@item
-Performs the various shell expansions (@pxref{Shell Expansions}), breaking
-the expanded tokens into lists of filenames (@pxref{Filename Expansion})
-and commands and arguments.
-
-@item
-Performs any necessary redirections (@pxref{Redirections}) and removes
-the redirection operators and their operands from the argument list.
-
-@item
-Executes the command (@pxref{Executing Commands}).
-
-@item
-Optionally waits for the command to complete and collects its exit
-status (@pxref{Exit Status}).
-
-@end enumerate
-
-@node Quoting
-@subsection Quoting
-@cindex quoting
-@menu
-* Escape Character::	How to remove the special meaning from a single
-			character.
-* Single Quotes::	How to inhibit all interpretation of a sequence
-			of characters.
-* Double Quotes::	How to suppress most of the interpretation of a
-			sequence of characters.
-* ANSI-C Quoting::	How to expand ANSI-C sequences in quoted strings.
-
-* Locale Translation::	How to translate strings into different languages.
-@end menu
-
-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 shell metacharacters (@pxref{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
-@var{history expansion} character, usually @samp{!}, must be quoted
-to prevent history expansion.  @xref{Bash History Facilities}, for
-more details concerning history expansion.
-
-There are three quoting mechanisms: the
-@var{escape character}, single quotes, and double quotes.
-
-@node Escape Character
-@subsubsection Escape Character
-A non-quoted backslash @samp{\} is the Bash escape character.
-It preserves the literal value of the next character that follows,
-with the exception of @code{newline}.  If a @code{\newline} pair
-appears, and the backslash itself is not quoted, the @code{\newline}
-is treated as a line continuation (that is, it is removed from
-the input stream and effectively ignored).
-
-@node Single Quotes
-@subsubsection Single Quotes
-
-Enclosing characters in single quotes (@samp{'}) 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.
-
-@node Double Quotes
-@subsubsection Double Quotes
-
-Enclosing characters in double quotes (@samp{"}) preserves the literal value
-of all characters within the quotes, with the exception of
-@samp{$}, @samp{`}, and @samp{\}.
-The characters @samp{$} and @samp{`}
-retain their special meaning within double quotes (@pxref{Shell Expansions}).
-The backslash retains its special meaning only when followed by one of
-the following characters:
-@samp{$}, @samp{`}, @samp{"}, @samp{\}, or @code{newline}.
-Within double quotes, backslashes that are followed by one of these
-characters are removed.  Backslashes preceding characters without a
-special meaning are left unmodified.
-A double quote may be quoted within double quotes by preceding it with
-a backslash.
-When command history is being used, the double quote may not be used to
-quote the history expansion character.
-
-The special parameters @samp{*} and @samp{@@} have special meaning
-when in double quotes (@pxref{Shell Parameter Expansion}).
-
-@node ANSI-C Quoting
-@subsubsection ANSI-C Quoting
-@cindex quoting, ANSI
-
-Words of the form @code{$'@var{string}'} are treated specially.  The
-word expands to @var{string}, with backslash-escaped characters replaced
-as specified by the ANSI C standard.  Backslash escape sequences, if
-present, are decoded as follows:
-
-@table @code
-@item \a
-alert (bell)
-@item \b
-backspace
-@item \e
-an escape character (not ANSI C)
-@item \f
-form feed
-@item \n
-newline
-@item \r
-carriage return
-@item \t
-horizontal tab
-@item \v
-vertical tab
-@item \\
-backslash
-@item \'
-single quote
-@item \@var{nnn}
-the eight-bit character whose value is the octal value @var{nnn}
-(one to three digits)
-@item \x@var{HH}
-the eight-bit character whose value is the hexadecimal value @var{HH}
-(one or two hex digits)
-@item \c@var{x}
-a control-@var{x} character
-@end table
-
-@noindent
-The expanded result is single-quoted, as if the dollar sign had not
-been present.
-
-@node Locale Translation
-@subsubsection Locale-Specific Translation
-@cindex localization
-@cindex internationalization
-@cindex native languages
-@cindex translation, native languages
-
-A double-quoted string preceded by a dollar sign (@samp{$}) will cause
-the string to be translated according to the current locale.
-If the current locale is @code{C} or @code{POSIX}, the dollar sign
-is ignored.
-If the string is translated and replaced, the replacement is
-double-quoted.
-
-@vindex LC_MESSAGES
-@vindex TEXTDOMAIN
-@vindex TEXTDOMAINDIR
-Some systems use the message catalog selected by the @env{LC_MESSAGES}
-shell variable.  Others create the name of the message catalog from the
-value of the @env{TEXTDOMAIN} shell variable, possibly adding a
-suffix of @samp{.mo}.  If you use the @env{TEXTDOMAIN} variable, you
-may need to set the @env{TEXTDOMAINDIR} variable to the location of
-the message catalog files.  Still others use both variables in this
-fashion:
-@env{TEXTDOMAINDIR}/@env{LC_MESSAGES}/LC_MESSAGES/@env{TEXTDOMAIN}.mo.
-
-@node Comments
-@subsection Comments
-@cindex comments, shell
-
-In a non-interactive shell, or an interactive shell in which the
-@code{interactive_comments} option to the @code{shopt}
-builtin is enabled (@pxref{Bash Builtins}),
-a word beginning with @samp{#}
-causes that word and all remaining characters on that line to
-be ignored.  An interactive shell without the @code{interactive_comments}
-option enabled does not allow comments.  The @code{interactive_comments}
-option is on by default in interactive shells.
-@xref{Interactive Shells}, for a description of what makes
-a shell interactive.
-
-@node Shell Commands
-@section Shell Commands
-@cindex commands, shell
-
-A simple shell command such as @code{echo a b c} consists of the command
-itself followed by arguments, separated by spaces.
-
-More complex shell commands are composed of simple commands arranged together
-in a variety of ways: in a pipeline in which the output of one command
-becomes the input of a second, in a loop or conditional construct, or in
-some other grouping.
-
-@menu
-* Simple Commands::		The most common type of command.
-* Pipelines::			Connecting the input and output of several
-				commands.
-* Lists::			How to execute commands sequentially.
-* Compound Commands::		Shell commands for control flow.
-@end menu
-
-@node Simple Commands
-@subsection Simple Commands
-@cindex commands, simple
-
-A simple command is the kind of command encountered most often.
-It's just a sequence of words separated by @code{blank}s, terminated
-by one of the shell's control operators (@pxref{Definitions}).  The
-first word generally specifies a command to be executed, with the
-rest of the words being that command's arguments.
-
-The return status (@pxref{Exit Status}) of a simple command is
-its exit status as provided
-by the @sc{posix} 1003.1 @code{waitpid} function, or 128+@var{n} if
-the command was terminated by signal @var{n}.
-
-@node Pipelines
-@subsection Pipelines
-@cindex pipeline
-@cindex commands, pipelines
-
-A @code{pipeline} is a sequence of simple commands separated by
-@samp{|}.
-
-@rwindex time
-@rwindex !
-@cindex command timing
-The format for a pipeline is
-@example
-[@code{time} [@code{-p}]] [@code{!}] @var{command1} [@code{|} @var{command2} @dots{}]
-@end example
-
-@noindent
-The output of each command in the pipeline is connected via a pipe
-to the input of the next command.
-That is, each command reads the previous command's output.
-
-The reserved word @code{time} causes timing statistics
-to be printed for the pipeline once it finishes.
-The statistics currently consist of elapsed (wall-clock) time and
-user and system time consumed by the command's execution.
-The @option{-p} option changes the output format to that specified
-by @sc{posix}.
-The @env{TIMEFORMAT} variable may be set to a format string that
-specifies how the timing information should be displayed.
-@xref{Bash Variables}, for a description of the available formats.
-The use of @code{time} as a reserved word permits the timing of
-shell builtins, shell functions, and pipelines.  An external
-@code{time} command cannot time these easily.
-
-If the pipeline is not executed asynchronously (@pxref{Lists}), the
-shell waits for all commands in the pipeline to complete.
-
-Each command in a pipeline is executed in its own subshell
-(@pxref{Command Execution Environment}).  The exit
-status of a pipeline is the exit status of the last command in the
-pipeline, unless the @code{pipefail} option is enabled
-(@pxref{The Set Builtin}).
-If @code{pipefail} is enabled, the pipeline's return status is the
-value of the last (rightmost) command to exit with a non-zero status,
-or zero if all commands exit successfully.
-If the reserved word @samp{!} precedes the pipeline, the
-exit status is the logical negation of the exit status as described
-above.
-The shell waits for all commands in the pipeline to terminate before
-returning a value.
-
-@node Lists
-@subsection Lists of Commands
-@cindex commands, lists
-
-A @code{list} is a sequence of one or more pipelines separated by one
-of the operators @samp{;}, @samp{&}, @samp{&&}, or @samp{||},
-and optionally terminated by one of @samp{;}, @samp{&}, or a
-@code{newline}.
-
-Of these list operators, @samp{&&} and @samp{||}
-have equal precedence, followed by @samp{;} and @samp{&},
-which have equal precedence.
-
-A sequence of one or more newlines may appear in a @code{list}
-to delimit commands, equivalent to a semicolon.
-
-If a command is terminated by the control operator @samp{&},
-the shell executes the command asynchronously in a subshell.
-This is known as executing the command in the @var{background}.
-The shell does not wait for the command to finish, and the return
-status is 0 (true).
-When job control is not active (@pxref{Job Control}),
-the standard input for asynchronous commands, in the absence of any
-explicit redirections, is redirected from @code{/dev/null}.
-
-Commands separated by a @samp{;} 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 @samp{&&} and @samp{||}
-denote @sc{and} lists and @sc{or} lists, respectively.
-An @sc{and} list has the form
-@example
-@var{command1} && @var{command2}
-@end example
-
-@noindent
-@var{command2} is executed if, and only if, @var{command1}
-returns an exit status of zero.
-
-An @sc{or} list has the form
-@example
-@var{command1} || @var{command2}
-@end example
-
-@noindent
-@var{command2} is executed if, and only if, @var{command1}
-returns a non-zero exit status.
-
-The return status of
-@sc{and} and @sc{or} lists is the exit status of the last command
-executed in the list.
-
-@node Compound Commands
-@subsection Compound Commands
-@cindex commands, compound
-
-@menu
-* Looping Constructs::		Shell commands for iterative action.
-* Conditional Constructs::	Shell commands for conditional execution.
-* Command Grouping::		Ways to group commands.
-@end menu
-
-Compound commands are the shell programming constructs.
-Each construct begins with a reserved word or control operator and is
-terminated by a corresponding reserved word or operator.
-Any redirections (@pxref{Redirections}) associated with a compound command
-apply to all commands within that compound command unless explicitly overridden.
-
-Bash provides looping constructs, conditional commands, and mechanisms
-to group commands and execute them as a unit.
-
-@node Looping Constructs
-@subsubsection Looping Constructs
-@cindex commands, looping
-
-Bash supports the following looping constructs.
-
-Note that wherever a @samp{;} appears in the description of a
-command's syntax, it may be replaced with one or more newlines.
-
-@table @code
-@item until
-@rwindex until
-@rwindex do
-@rwindex done
-The syntax of the @code{until} command is:
-@example
-until @var{test-commands}; do @var{consequent-commands}; done
-@end example
-Execute @var{consequent-commands} as long as
-@var{test-commands} has an exit status which is not zero.
-The return status is the exit status of the last command executed
-in @var{consequent-commands}, or zero if none was executed.
-
-@item while
-@rwindex while
-The syntax of the @code{while} command is:
-@example
-while @var{test-commands}; do @var{consequent-commands}; done
-@end example
-
-Execute @var{consequent-commands} as long as
-@var{test-commands} has an exit status of zero.
-The return status is the exit status of the last command executed
-in @var{consequent-commands}, or zero if none was executed.
-
-@item for
-@rwindex for
-The syntax of the @code{for} command is:
-
-@example
-for @var{name} [in @var{words} @dots{}]; do @var{commands}; done
-@end example
-Expand @var{words}, and execute @var{commands} once for each member
-in the resultant list, with @var{name} bound to the current member.
-If @samp{in @var{words}} is not present, the @code{for} command
-executes the @var{commands} once for each positional parameter that is
-set, as if @samp{in "$@@"} had been specified
-(@pxref{Special Parameters}).
-The return status is the exit status of the last command that executes.
-If there are no items in the expansion of @var{words}, no commands are
-executed, and the return status is zero.
-
-An alternate form of the @code{for} command is also supported:
-
-@example
-for (( @var{expr1} ; @var{expr2} ; @var{expr3} )) ; do @var{commands} ; done
-@end example
-First, the arithmetic expression @var{expr1} is evaluated according
-to the rules described below (@pxref{Shell Arithmetic}).
-The arithmetic expression @var{expr2} is then evaluated repeatedly
-until it evaluates to zero.   
-Each time @var{expr2} evaluates to a non-zero value, @var{commands} are
-executed and the arithmetic expression @var{expr3} is evaluated.       
-If any expression is omitted, it behaves as if it evaluates to 1.
-The return value is the exit status of the last command in @var{list}
-that is executed, or false if any of the expressions is invalid.
-
-@end table
-
-The @code{break} and @code{continue} builtins (@pxref{Bourne Shell Builtins})
-may be used to control loop execution.
-
-@node Conditional Constructs
-@subsubsection Conditional Constructs
-@cindex commands, conditional
-
-@table @code
-@item if
-@rwindex if
-@rwindex then
-@rwindex else
-@rwindex elif
-@rwindex fi
-The syntax of the @code{if} command is:
-
-@example
-if @var{test-commands}; then
-  @var{consequent-commands};
-[elif @var{more-test-commands}; then
-  @var{more-consequents};]
-[else @var{alternate-consequents};]
-fi
-@end example
-
-The @var{test-commands} list is executed, and if its return status is zero,
-the @var{consequent-commands} list is executed.
-If @var{test-commands} returns a non-zero status, each @code{elif} list
-is executed in turn, and if its exit status is zero,
-the corresponding @var{more-consequents} is executed and the   
-command completes.
-If @samp{else @var{alternate-consequents}} is present, and
-the final command in the final @code{if} or @code{elif} clause
-has a non-zero exit status, then @var{alternate-consequents} is executed.
-The return status is the exit status of the last command executed, or
-zero if no condition tested true.
-
-@item case
-@rwindex case
-@rwindex in
-@rwindex esac
-The syntax of the @code{case} command is:
-
-@example
-@code{case @var{word} in [ [(] @var{pattern} [| @var{pattern}]@dots{}) @var{command-list} ;;]@dots{} esac}
-@end example
-
-@code{case} will selectively execute the @var{command-list} corresponding to
-the first @var{pattern} that matches @var{word}.
-The @samp{|} is used to separate multiple patterns, and the @samp{)}
-operator terminates a pattern list.
-A list of patterns and an associated command-list is known
-as a @var{clause}.  Each clause must be terminated with @samp{;;}.
-The @var{word} undergoes tilde expansion, parameter expansion, command
-substitution, arithmetic expansion, and quote removal before matching is
-attempted.  Each @var{pattern} undergoes tilde expansion, parameter
-expansion, command substitution, and arithmetic expansion.
-
-There may be an arbitrary number of @code{case} clauses, each terminated
-by a @samp{;;}.  The first pattern that matches determines the
-command-list that is executed.
-
-Here is an example using @code{case} in a script that could be used to
-describe one interesting feature of an animal:
-
-@example
-echo -n "Enter the name of an animal: "
-read ANIMAL
-echo -n "The $ANIMAL has "
-case $ANIMAL in
-  horse | dog | cat) echo -n "four";;
-  man | kangaroo ) echo -n "two";;
-  *) echo -n "an unknown number of";;
-esac
-echo " legs."
-@end example
-
-@noindent
-The return status is zero if no @var{pattern} is matched.  Otherwise, the
-return status is the exit status of the @var{command-list} executed.
-
-@item select
-@rwindex select
-
-The @code{select} construct allows the easy generation of menus.
-It has almost the same syntax as the @code{for} command:
-
-@example
-select @var{name} [in @var{words} @dots{}]; do @var{commands}; done
-@end example
-
-The list of words following @code{in} is expanded, generating a list
-of items.  The set of expanded words is printed on the standard
-error output stream, each preceded by a number.  If the
-@samp{in @var{words}} is omitted, the positional parameters are printed,
-as if @samp{in "$@@"} had been specifed.
-The @env{PS3} prompt is then displayed and a line is read from the
-standard input.
-If the line consists of a number corresponding to one of the displayed
-words, then the value of @var{name} is set to that word.
-If the line is empty, the words and prompt are displayed again.
-If @code{EOF} is read, the @code{select} command completes.
-Any other value read causes @var{name} to be set to null.
-The line read is saved in the variable @env{REPLY}.
-
-The @var{commands} are executed after each selection until a
-@code{break} command is executed, at which
-point the @code{select} command completes.
-
-Here is an example that allows the user to pick a filename from the
-current directory, and displays the name and index of the file
-selected.
-
-@example
-select fname in *;
-do
-	echo you picked $fname \($REPLY\)
-	break;
-done
-@end example
-
-@item ((@dots{}))
-@example
-(( @var{expression} ))
-@end example
-
-The arithmetic @var{expression} is evaluated according to the rules
-described below (@pxref{Shell Arithmetic}).
-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
-@example
-let "@var{expression}"
-@end example
-@noindent
-@xref{Bash Builtins}, for a full description of the @code{let} builtin.
-
-@item [[@dots{}]]
-@rwindex [[
-@rwindex ]]
-@example
-[[ @var{expression} ]]
-@end example
-
-Return a status of 0 or 1 depending on the evaluation of
-the conditional expression @var{expression}.
-Expressions are composed of the primaries described below in
-@ref{Bash Conditional Expressions}.
-Word splitting and filename expansion are not performed on the words
-between the @samp{[[} and @samp{]]}; tilde expansion, parameter and
-variable expansion, arithmetic expansion, command substitution, process
-substitution, and quote removal are performed.
-Conditional operators such as @samp{-f} must be unquoted to be recognized
-as primaries.
-
-When the @samp{==} and @samp{!=} operators are used, the string to the
-right of the operator is considered a pattern and matched according
-to the rules described below in @ref{Pattern Matching}.
-The return value is 0 if the string matches or does not match
-the pattern, respectively, and 1 otherwise.
-Any part of the pattern may be quoted to force it to be matched as a
-string.
-
-An additional binary operator, @samp{=~}, is available, with the same
-precedence as @samp{==} and @samp{!=}.
-When it is used, the string to the right of the operator is considered
-an extended regular expression and matched accordingly (as in @i{regex}3)).  
-The return value is 0 if the string matches
-the pattern, and 1 otherwise.
-If the regular expression is syntactically incorrect, the conditional
-expression's return value is 2.
-If the shell option @code{nocaseglob}
-(see the description of @code{shopt} in @ref{Bash Builtins})
-is enabled, the match is performed without regard to the case
-of alphabetic characters.
-Substrings matched by parenthesized subexpressions within the regular
-expression are saved in the array variable @code{BASH_REMATCH}.
-The element of @code{BASH_REMATCH} with index 0 is the portion of the string
-matching the entire regular expression.
-The element of @code{BASH_REMATCH} with index @var{n} is the portion of the
-string matching the @var{n}th parenthesized subexpression.
-
-Expressions may be combined using the following operators, listed
-in decreasing order of precedence:
-
-@table @code
-@item ( @var{expression} )
-Returns the value of @var{expression}.
-This may be used to override the normal precedence of operators.
-
-@item ! @var{expression}
-True if @var{expression} is false.
-
-@item @var{expression1} && @var{expression2}
-True if both @var{expression1} and @var{expression2} are true.
-
-@item @var{expression1} || @var{expression2}
-True if either @var{expression1} or @var{expression2} is true.
-@end table
-@noindent
-The @code{&&} and @code{||} operators do not evaluate @var{expression2} if the
-value of @var{expression1} is sufficient to determine the return
-value of the entire conditional expression.
-
-@end table
-
-@node Command Grouping
-@subsubsection Grouping Commands
-@cindex commands, grouping
-
-Bash provides two ways to group a list of commands to be executed
-as a unit.  When commands are grouped, redirections may be applied
-to the entire command list.  For example, the output of all the
-commands in the list may be redirected to a single stream.
-
-@table @code
-@item ()
-@example
-( @var{list} )
-@end example
-
-Placing a list of commands between parentheses causes a subshell
-environment to be created (@pxref{Command Execution Environment}), and each
-of the commands in @var{list} to be executed in that subshell.  Since the
-@var{list} is executed in a subshell, variable assignments do not remain in
-effect after the subshell completes. 
-
-@item @{@}
-@rwindex @{
-@rwindex @}
-@example
-@{ @var{list}; @}
-@end example
-
-Placing a list of commands between curly braces causes the list to
-be executed in the current shell context.  No subshell is created.
-The semicolon (or newline) following @var{list} is required.
-@end table
-
-In addition to the creation of a subshell, there is a subtle difference
-between these two constructs due to historical reasons.  The braces
-are @code{reserved words}, so they must be separated from the @var{list}
-by @code{blank}s.  The parentheses are @code{operators}, and are
-recognized as separate tokens by the shell even if they are not separated
-from the @var{list} by whitespace.
-
-The exit status of both of these constructs is the exit status of
-@var{list}.
-
-@node Shell Functions
-@section Shell Functions
-@cindex shell function
-@cindex functions, shell
-
-Shell functions are a way to group commands for later execution
-using a single name for the group.  They are executed just like
-a "regular" command.
-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.
-Shell functions are executed in the current
-shell context; no new process is created to interpret them.
-
-Functions are declared using this syntax:
-@rwindex function
-@example
-[ @code{function} ] @var{name} () @var{compound-command} [ @var{redirections} ]
-@end example
-
-This defines a shell function named @var{name}.  The reserved
-word @code{function} is optional.
-If the @code{function} reserved
-word is supplied, the parentheses are optional.
-The @var{body} of the function is the compound command
-@var{compound-command} (@pxref{Compound Commands}).
-That command is usually a @var{list} enclosed between @{ and @}, but
-may be any compound command listed above.
-@var{compound-command} is executed whenever @var{name} is specified as the
-name of a command.
-Any redirections (@pxref{Redirections}) associated with the shell function
-are performed when the function is executed.
-
-The exit status of a function definition is zero unless a syntax error
-occurs or a readonly function with the same name already exists.
-When executed, the exit status of a function is the exit status of the
-last command executed in the body.
-
-Note that for historical reasons, in the most common usage the curly braces
-that surround the body of the function must be separated from the body by
-@code{blank}s or newlines.
-This is because the braces are reserved words and are only recognized
-as such when they are separated by whitespace.
-Also, when using the braces, the @var{list} must be terminated by a semicolon,
-a @samp{&}, or a newline.
-
-When a function is executed, the arguments to the
-function become the positional parameters
-during its execution (@pxref{Positional Parameters}).
-The special parameter @samp{#} that expands to the number of
-positional parameters is updated to reflect the change.
-Special parameter @code{0} is unchanged.
-The first element of the @env{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 @env{DEBUG} trap
-below) is not inherited unless the function has been given the
-@code{trace} attribute using the @code{declare} builtin or
-the @code{-o functrace} option has been enabled with
-the @code{set} builtin,
-(in which case all functions inherit the @code{DEBUG} trap).
-@xref{Bourne Shell Builtins}, for the description of the
-@code{trap} builtin.
-
-If the builtin command @code{return}
-is executed in a function, the function completes and
-execution resumes with the next command after the function
-call.
-Any command associated with the @code{RETURN} trap is executed
-before execution resumes.
-When a function completes, the values of the
-positional parameters and the special parameter @samp{#}
-are restored to the values they had prior to the function's
-execution.  If a numeric argument is given to @code{return},
-that is the function's return status; otherwise the function's
-return status is the exit status of the last command executed
-before the @code{return}.
-
-Variables local to the function may be declared with the
-@code{local} builtin.  These variables are visible only to
-the function and the commands it invokes.
-
-Function names and definitions may be listed with the
-@option{-f} option to the @code{declare} or @code{typeset}
-builtin commands (@pxref{Bash Builtins}).
-The @option{-F} option to @code{declare} or @code{typeset}
-will list the function names only
-(and optionally the source file and line number, if the @code{extdebug}
-shell option is enabled).
-Functions may be exported so that subshells
-automatically have them defined with the
-@option{-f} option to the @code{export} builtin
-(@pxref{Bourne Shell Builtins}).
-Note that shell functions and variables with the same name may result
-in multiple identically-named entries in the environment passed to the
-shell's children.
-Care should be taken in cases where this may cause a problem.
-
-Functions may be recursive.  No limit is placed on the number of
-recursive  calls.
-
-@node Shell Parameters
-@section Shell Parameters
-@cindex parameters
-@cindex variable, shell
-@cindex shell variable
-
-@menu
-* Positional Parameters::	The shell's command-line arguments.
-* Special Parameters::		Parameters denoted by special characters.
-@end menu
-
-A @var{parameter} is an entity that stores values.
-It can be a @code{name}, a number, or one of the special characters
-listed below.
-A @var{variable} is a parameter denoted by a @code{name}.
-A variable has a @var{value} and zero or more @var{attributes}.
-Attributes are assigned using the @code{declare} builtin command
-(see the description of the @code{declare} builtin in @ref{Bash Builtins}).
-
-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 @code{unset} builtin command.
-
-A variable may be assigned to by a statement of the form
-@example
-@var{name}=[@var{value}]
-@end example
-@noindent
-If @var{value}
-is not given, the variable is assigned the null string.  All
-@var{value}s undergo tilde expansion, parameter and variable expansion,
-command substitution, arithmetic expansion, and quote
-removal (detailed below).  If the variable has its @code{integer}
-attribute set, then @var{value} 
-is evaluated as an arithmetic expression even if the @code{$((@dots{}))}
-expansion is not used (@pxref{Arithmetic Expansion}).
-Word splitting is not performed, with the exception
-of @code{"$@@"} as explained below.
-Filename expansion is not performed.
-Assignment statements may also appear as arguments to the
-@code{alias}, 
-@code{declare}, @code{typeset}, @code{export}, @code{readonly},
-and @code{local} builtin commands.
-
-@node Positional Parameters
-@subsection Positional Parameters
-@cindex parameters, positional
-
-A @var{positional parameter} is a parameter denoted by one or more
-digits, other than the single digit @code{0}.  Positional parameters are
-assigned from the shell's arguments when it is invoked,
-and may be reassigned using the @code{set} builtin command.
-Positional parameter @code{N} may be referenced as @code{$@{N@}}, or
-as @code{$N} when @code{N} consists of a single digit.
-Positional parameters may not be assigned to with assignment statements.
-The @code{set} and @code{shift} builtins are used to set and
-unset them (@pxref{Shell Builtin Commands}).
-The positional parameters are
-temporarily replaced when a shell function is executed
-(@pxref{Shell Functions}).
-
-When a positional parameter consisting of more than a single
-digit is expanded, it must be enclosed in braces.
-
-@node Special Parameters
-@subsection Special Parameters
-@cindex parameters, special
-
-The shell treats several parameters specially.  These parameters may
-only be referenced; assignment to them is not allowed.
-
-@vtable @code
-
-@item *
-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 @env{IFS}
-special variable.  That is, @code{"$*"} is equivalent
-to @code{"$1@var{c}$2@var{c}@dots{}"}, where @var{c}
-is the first character of the value of the @code{IFS}
-variable.
-If @env{IFS} is unset, the parameters are separated by spaces.
-If @env{IFS} is null, the parameters are joined without intervening
-separators.
-
-
-@item @@
-Expands to the positional parameters, starting from one.  When the
-expansion occurs within double quotes, each parameter expands to a
-separate word.  That is, @code{"$@@"} is equivalent to
-@code{"$1" "$2" @dots{}}.
-When there are no positional parameters, @code{"$@@"} and
-@code{$@@}
-expand to nothing (i.e., they are removed).
-
-@item #
-Expands to the number of positional parameters in decimal.
-
-@item ?
-Expands to the exit status of the most recently executed foreground
-pipeline.
-
-@item -
-(A hyphen.)  Expands to the current option flags as specified upon
-invocation, by the @code{set}
-builtin command, or those set by the shell itself
-(such as the @option{-i} option).
-
-@item $
-Expands to the process @sc{id} of the shell.  In a @code{()} subshell, it
-expands to the process @sc{id} of the invoking shell, not the subshell.
-
-@item !
-Expands to the process @sc{id} of the most recently executed background
-(asynchronous) command.
-
-@item 0
-Expands to the name of the shell or shell script.  This is set at
-shell initialization.  If Bash is invoked with a file of commands
-(@pxref{Shell Scripts}), @code{$0} is set to the name of that file.
-If Bash is started with the @option{-c} option (@pxref{Invoking Bash}),
-then @code{$0} is set to the first argument after the string to be
-executed, if one is present.  Otherwise, it is set
-to the filename used to invoke Bash, as given by argument zero.
-
-@item _
-(An underscore.)
-At shell startup, set to the absolute filename of the shell or shell
-script being executed as passed in the argument list.
-Subsequently, expands to the last argument to the previous command,
-after expansion.   
-Also set to the full pathname 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.
-@end vtable
-
-@node Shell Expansions
-@section Shell Expansions
-@cindex expansion
-
-Expansion is performed on the command line after it has been split into
-@code{token}s.  There are seven kinds of expansion performed:
-@itemize @bullet
-@item brace expansion
-@item tilde expansion
-@item parameter and variable expansion
-@item command substitution
-@item arithmetic expansion
-@item word splitting
-@item filename expansion
-@end itemize
-
-@menu
-* Brace Expansion::		Expansion of expressions within braces.
-* Tilde Expansion::		Expansion of the ~ character.
-* Shell Parameter Expansion::	How Bash expands variables to their values.
-* Command Substitution::	Using the output of a command as an argument.
-* Arithmetic Expansion::	How to use arithmetic in shell expansions.
-* Process Substitution::	A way to write and read to and from a
-				command.
-* Word Splitting::	How the results of expansion are split into separate
-			arguments.
-* Filename Expansion::	A shorthand for specifying filenames matching patterns.
-* Quote Removal::	How and when quote characters are removed from
-			words.
-@end menu
-
-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 filename
-expansion.
-
-On systems that can support it, there is an additional expansion
-available: @var{process substitution}.  This is performed at the
-same time as parameter, variable, and arithmetic expansion and
-command substitution.
-
-Only brace expansion, word splitting, and filename 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
-@code{"$@@"} (@pxref{Special Parameters}) and @code{"$@{@var{name}[@@]@}"}
-(@pxref{Arrays}).
-
-After all expansions, @code{quote removal} (@pxref{Quote Removal})
-is performed.
-
-@node Brace Expansion
-@subsection Brace Expansion
-@cindex brace expansion
-@cindex expansion, brace
-
-Brace expansion is a mechanism by which arbitrary strings may be generated.
-This mechanism is similar to
-@var{filename expansion} (@pxref{Filename Expansion}),
-but the file names generated need not exist.
-Patterns to be brace expanded take the form of an optional @var{preamble},
-followed by either a series of comma-separated strings or a sequnce expression
-between a pair of braces,
-followed by an optional @var{postscript}.
-The preamble is prefixed to each string contained within the braces, and
-the postscript is then appended to each resulting string, expanding left
-to right.
-
-Brace expansions may be nested.
-The results of each expanded string are not sorted; left to right order
-is preserved.
-For example,
-@example
-bash$ echo a@{d,c,b@}e
-ade ace abe
-@end example
-
-A sequence expression takes the form @code{@{@var{x}..@var{y}@}},
-where @var{x} and @var{y} are either integers or single characters.
-When integers are supplied, the expression expands to each number between
-@var{x} and @var{y}, inclusive.
-When characters are supplied, the expression expands to each character
-lexicographically between @var{x} and @var{y}, inclusive.  Note that
-both @var{x} and @var{y} must be of the same type.
-
-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.
-To avoid conflicts with parameter expansion, the string @samp{$@{}
-is not considered eligible for brace expansion.
-
-A correctly-formed brace expansion must contain unquoted opening
-and closing braces, and at least one unquoted comma or a valid
-sequence expression.
-Any incorrectly formed brace expansion is left unchanged.
-
-A @{ or @samp{,} may be quoted with a backslash to prevent its
-being considered part of a brace expression.
-To avoid conflicts with parameter expansion, the string @samp{$@{}
-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:
-@example
-mkdir /usr/local/src/bash/@{old,new,dist,bugs@}
-@end example
-or
-@example
-chown root /usr/@{ucb/@{ex,edit@},lib/@{ex?.?*,how_ex@}@}
-@end example
-
-@node Tilde Expansion
-@subsection Tilde Expansion
-@cindex tilde expansion
-@cindex expansion, tilde
-
-If a word begins with an unquoted tilde character (@samp{~}), all of the
-characters up to the first unquoted slash (or all characters,
-if there is no unquoted slash) are considered a @var{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 @var{login name}.
-If this login name is the null string, the tilde is replaced with the
-value of the @env{HOME} shell variable.
-If @env{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 @samp{~+}, the value of
-the shell variable @env{PWD} replaces the tilde-prefix.
-If the tilde-prefix is @samp{~-}, the value of the shell variable
-@env{OLDPWD}, if it is set, is substituted.
-
-If the characters following the tilde in the tilde-prefix consist of a
-number @var{N}, optionally prefixed by a @samp{+} or a @samp{-},
-the tilde-prefix is replaced with the
-corresponding element from the directory stack, as it would be displayed
-by the @code{dirs} builtin invoked with the characters following tilde
-in the tilde-prefix as an argument (@pxref{The Directory Stack}).
-If the tilde-prefix, sans the tilde, consists of a number without a
-leading @samp{+} or @samp{-}, @samp{+} is assumed.
-
-If the login name is invalid, or the tilde expansion fails, the word is
-left unchanged.
-
-Each variable assignment is checked for unquoted tilde-prefixes immediately
-following a @samp{:} or @samp{=}.
-In these cases, tilde expansion is also performed.
-Consequently, one may use file names with tildes in assignments to
-@env{PATH}, @env{MAILPATH}, and @env{CDPATH},
-and the shell assigns the expanded value.
-
-The following table shows how Bash treats unquoted tilde-prefixes:
-
-@table @code
-@item ~
-The value of @code{$HOME}
-@item ~/foo
-@file{$HOME/foo}
-
-@item ~fred/foo
-The subdirectory @code{foo} of the home directory of the user
-@code{fred}
-
-@item ~+/foo
-@file{$PWD/foo}
-
-@item ~-/foo
-@file{$@{OLDPWD-'~-'@}/foo}
-
-@item ~@var{N}
-The string that would be displayed by @samp{dirs +@var{N}}
-
-@item ~+@var{N}
-The string that would be displayed by @samp{dirs +@var{N}}
-
-@item ~-@var{N}
-The string that would be displayed by @samp{dirs -@var{N}}
-
-@end table
-
-@node Shell Parameter Expansion
-@subsection Shell Parameter Expansion
-@cindex parameter expansion
-@cindex expansion, parameter
-
-The @samp{$} 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 @samp{@}}
-not escaped by a backslash or within a quoted string, and not within an
-embedded arithmetic expansion, command substitution, or parameter
-expansion.
-
-The basic form of parameter expansion is $@{@var{parameter}@}.
-The value of @var{parameter} is substituted.  The braces are required
-when @var{parameter}
-is a positional parameter with more than one digit,
-or when @var{parameter}
-is followed by a character that is not to be
-interpreted as part of its name.
-
-If the first character of @var{parameter} is an exclamation point,
-a level of variable indirection is introduced.
-Bash uses the value of the variable formed from the rest of
-@var{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 @var{parameter} itself.
-This is known as @code{indirect expansion}.
-The exceptions to this are the expansions of $@{!@var{prefix*}@}
-and $@{!@var{name}[@@]@}
-described below.
-The exclamation point must immediately follow the left brace in order to
-introduce indirection.
-
-In each of the cases below, @var{word} is subject to tilde expansion,
-parameter expansion, command substitution, and arithmetic expansion.
-
-When not performing substring expansion, Bash tests for a parameter
-that is unset or null; omitting the colon results in a test only for a
-parameter that is unset.  Put another way, if the colon is included,
-the operator tests for both existence and that the value is not null;
-if the colon is omitted, the operator tests only for existence.
-
-@table @code
-
-@item $@{@var{parameter}:@minus{}@var{word}@}
-If @var{parameter} is unset or null, the expansion of
-@var{word} is substituted.  Otherwise, the value of
-@var{parameter} is substituted.
-
-@item $@{@var{parameter}:=@var{word}@}
-If @var{parameter}
-is unset or null, the expansion of @var{word}
-is assigned to @var{parameter}.
-The value of @var{parameter} is then substituted. 
-Positional parameters and special parameters may not be assigned to
-in this way.
-
-@item $@{@var{parameter}:?@var{word}@}
-If @var{parameter}
-is null or unset, the expansion of @var{word} (or a message
-to that effect if @var{word}
-is not present) is written to the standard error and the shell, if it
-is not interactive, exits.  Otherwise, the value of @var{parameter} is
-substituted.
-
-@item $@{@var{parameter}:+@var{word}@}
-If @var{parameter}
-is null or unset, nothing is substituted, otherwise the expansion of
-@var{word} is substituted.
-
-@item $@{@var{parameter}:@var{offset}@}
-@itemx $@{@var{parameter}:@var{offset}:@var{length}@}
-Expands to up to @var{length} characters of @var{parameter}
-starting at the character specified by @var{offset}.
-If @var{length} is omitted, expands to the substring of
-@var{parameter} starting at the character specified by @var{offset}.
-@var{length} and @var{offset} are arithmetic expressions
-(@pxref{Shell Arithmetic}).
-This is referred to as Substring Expansion.
-
-@var{length} must evaluate to a number greater than or equal to zero.
-If @var{offset} evaluates to a number less than zero, the value
-is used as an offset from the end of the value of @var{parameter}.
-If @var{parameter} is @samp{@@}, the result is @var{length} positional
-parameters beginning at @var{offset}.
-If @var{parameter} is an array name indexed by @samp{@@} or @samp{*},
-the result is the @var{length}
-members of the array beginning with @code{$@{@var{parameter}[@var{offset}]@}}.
-Substring indexing is zero-based unless the positional parameters
-are used, in which case the indexing starts at 1.
-
-@item $@{!@var{prefix}*@}
-@itemx $@{!@var{prefix}@@@}
-Expands to the names of variables whose names begin with @var{prefix},
-separated by the first character of the @env{IFS} special variable.
-
-@item $@{!@var{name}[@@]@}
-@itemx $@{!@var{name}[*]@}
-If @var{name} is an array variable, expands to the list of array indices
-(keys) assigned in @var{name}.
-If @var{name} is not an array, expands to 0 if @var{name} is set and null
-otherwise.
-When @samp{@@} is used and the expansion appears within double quotes, each
-key expands to a separate word.
-
-@item $@{#@var{parameter}@}
-The length in characters of the expanded value of @var{parameter} is
-substituted.
-If @var{parameter} is @samp{*} or @samp{@@}, the value substituted
-is the number of positional parameters.
-If @var{parameter} is an array name subscripted by @samp{*} or @samp{@@}, 
-the value substituted is the number of elements in the array.
-
-@item $@{@var{parameter}#@var{word}@}
-@itemx $@{@var{parameter}##@var{word}@}
-The @var{word}
-is expanded to produce a pattern just as in filename
-expansion (@pxref{Filename Expansion}).  If the pattern matches
-the beginning of the expanded value of @var{parameter},
-then the result of the expansion is the expanded value of @var{parameter}
-with the shortest matching pattern (the @samp{#} case) or the
-longest matching pattern (the @samp{##} case) deleted.
-If @var{parameter} is @samp{@@} or @samp{*},
-the pattern removal operation is applied to each positional
-parameter in turn, and the expansion is the resultant list.
-If @var{parameter} is an array variable subscripted with
-@samp{@@} or @samp{*},
-the pattern removal operation is applied to each member of the
-array in turn, and the expansion is the resultant list.
-
-@item $@{@var{parameter}%@var{word}@}
-@itemx $@{@var{parameter}%%@var{word}@}
-The @var{word} is expanded to produce a pattern just as in
-filename expansion.
-If the pattern matches a trailing portion of the expanded value of
-@var{parameter}, then the result of the expansion is the value of
-@var{parameter} with the shortest matching pattern (the @samp{%} case)
-or the longest matching pattern (the @samp{%%} case) deleted.
-If @var{parameter} is @samp{@@} or @samp{*},
-the pattern removal operation is applied to each positional
-parameter in turn, and the expansion is the resultant list.
-If @var{parameter}
-is an array variable subscripted with @samp{@@} or @samp{*},
-the pattern removal operation is applied to each member of the
-array in turn, and the expansion is the resultant list.
-
-@item $@{@var{parameter}/@var{pattern}/@var{string}@} 
-@itemx $@{@var{parameter}//@var{pattern}/@var{string}@}
-
-The @var{pattern} is expanded to produce a pattern just as in
-filename expansion.
-@var{Parameter} is expanded and the longest match of @var{pattern}
-against its value is replaced with @var{string}.
-In the first form, only the first match is replaced.
-The second form causes all matches of @var{pattern} to be
-replaced with @var{string}.
-If @var{pattern} begins with @samp{#}, it must match at the beginning
-of the expanded value of @var{parameter}.
-If @var{pattern} begins with @samp{%}, it must match at the end
-of the expanded value of @var{parameter}.
-If @var{string} is null, matches of @var{pattern} are deleted
-and the @code{/} following @var{pattern} may be omitted.
-If @var{parameter} is @samp{@@} or @samp{*},
-the substitution operation is applied to each positional
-parameter in turn, and the expansion is the resultant list.
-If @var{parameter}
-is an array variable subscripted with @samp{@@} or @samp{*},
-the substitution operation is applied to each member of the
-array in turn, and the expansion is the resultant list.
-
-@end table
-
-@node Command Substitution
-@subsection Command Substitution
-@cindex command substitution
-
-Command substitution allows the output of a command to replace
-the command itself.
-Command substitution occurs when a command is enclosed as follows:
-@example
-$(@var{command})
-@end example
-@noindent
-or
-@example
-`@var{command}`
-@end example
-
-@noindent
-Bash performs the expansion by executing @var{command} and
-replacing the command substitution with the standard output of the
-command, with any trailing newlines deleted.
-Embedded newlines are not deleted, but they may be removed during
-word splitting.
-The command substitution @code{$(cat @var{file})} can be
-replaced by the equivalent but faster @code{$(< @var{file})}.
-
-When the old-style backquote form of substitution is used,
-backslash retains its literal meaning except when followed by
-@samp{$}, @samp{`}, or @samp{\}. 
-The first backquote not preceded by a backslash terminates the
-command substitution.
-When using the @code{$(@var{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
-filename expansion are not performed on the results.
-
-@node Arithmetic Expansion
-@subsection Arithmetic Expansion
-@cindex expansion, arithmetic
-@cindex arithmetic expansion
-
-Arithmetic expansion allows the evaluation of an arithmetic expression
-and the substitution of the result.  The format for arithmetic expansion is:
-
-@example
-$(( @var{expression} ))
-@end example
-
-The expression is treated as if it were within double quotes, but
-a double quote inside the parentheses is not treated specially.
-All tokens in the expression undergo parameter expansion, command
-substitution, and quote removal.
-Arithmetic expansions may be nested. 
-
-The evaluation is performed according to the rules listed below
-(@pxref{Shell Arithmetic}).
-If the expression is invalid, Bash prints a message indicating
-failure to the standard error and no substitution occurs.
-
-@node Process Substitution
-@subsection Process Substitution
-@cindex process substitution
-
-Process substitution is supported on systems that support named
-pipes (@sc{fifo}s) or the @file{/dev/fd} method of naming open files.
-It takes the form of 
-@example
-<(@var{list})
-@end example
-@noindent
-or
-@example
->(@var{list})
-@end example
-@noindent
-The process @var{list} is run with its input or output connected to a
-@sc{fifo} or some file in @file{/dev/fd}.  The name of this file is
-passed as an argument to the current command as the result of the
-expansion.  If the @code{>(@var{list})} form is used, writing to
-the file will provide input for @var{list}.  If the
-@code{<(@var{list})} form is used, the file passed as an
-argument should be read to obtain the output of @var{list}.
-Note that no space may appear between the @code{<} or @code{>}
-and the left parenthesis, otherwise the construct would be interpreted
-as a redirection.
-
-When available, process substitution is performed simultaneously with
-parameter and variable expansion, command substitution, and arithmetic
-expansion.
-
-@node Word Splitting
-@subsection Word Splitting
-@cindex word splitting
-
-The shell scans the results of parameter expansion, command substitution,
-and arithmetic expansion that did not occur within double quotes for
-word splitting.
-
-The shell treats each character of @env{$IFS}
-as a delimiter, and splits the results of the other
-expansions into words on these characters.  If
-@env{IFS} is unset, or its value is exactly @code{<space><tab><newline>},
-the default, then any sequence of @env{IFS}
-characters serves to delimit words.  If @env{IFS}
-has a value other than the default, then sequences of
-the whitespace characters @code{space} and @code{tab}
-are ignored at the beginning and end of the
-word, as long as the whitespace character is in the
-value of @env{IFS} (an @env{IFS} whitespace character).
-Any character in @env{IFS} that is not @env{IFS}
-whitespace, along with any adjacent @env{IFS}
-whitespace characters, delimits a field.  A sequence of @env{IFS}
-whitespace characters is also treated as a delimiter.
-If the value of @env{IFS} is null, no word splitting occurs.
-
-Explicit null arguments (@code{""} or @code{''}) are retained.
-Unquoted implicit null arguments, resulting from the expansion of
-parameters that have no values, are removed.
-If a parameter with no value is expanded within double quotes, a
-null argument results and is retained.
-
-Note that if no expansion occurs, no splitting
-is performed.
-
-@node Filename Expansion
-@subsection Filename Expansion
-@menu
-* Pattern Matching::	How the shell matches patterns.
-@end menu
-@cindex expansion, filename
-@cindex expansion, pathname
-@cindex filename expansion
-@cindex pathname expansion
-
-After word splitting, unless the @option{-f} option has been set
-(@pxref{The Set Builtin}), Bash scans each word for the characters
-@samp{*}, @samp{?}, and @samp{[}.
-If one of these characters appears, then the word is
-regarded as a @var{pattern},
-and replaced with an alphabetically sorted list of
-file names matching the pattern. If no matching file names are found,
-and the shell option @code{nullglob} is disabled, the word is left
-unchanged.
-If the @code{nullglob} option is set, and no matches are found, the word
-is removed.
-If the @code{failglob} shell option is set, and no matches are found,
-an error message is printed and the command is not executed.
-If the shell option @code{nocaseglob} is enabled, the match is performed
-without regard to the case of alphabetic characters.
-
-When a pattern is used for filename generation, the character @samp{.}
-at the start of a filename or immediately following a slash
-must be matched explicitly, unless the shell option @code{dotglob} is set.
-When matching a file name, the slash character must always be
-matched explicitly.
-In other cases, the @samp{.} character is not treated specially.
-
-See the description of @code{shopt} in @ref{Bash Builtins},
-for a description of the @code{nocaseglob}, @code{nullglob},
-@code{failglob}, and @code{dotglob} options.
-
-The @env{GLOBIGNORE}
-shell variable may be used to restrict the set of filenames matching a
-pattern.  If @env{GLOBIGNORE}
-is set, each matching filename that also matches one of the patterns in
-@env{GLOBIGNORE} is removed from the list of matches.  The filenames
-@file{.} and @file{..}
-are always ignored when @env{GLOBIGNORE}
-is set and not null.
-However, setting @env{GLOBIGNORE} to a non-null value has the effect of
-enabling the @code{dotglob}
-shell option, so all other filenames beginning with a
-@samp{.} will match.
-To get the old behavior of ignoring filenames beginning with a
-@samp{.}, make @samp{.*} one of the patterns in @env{GLOBIGNORE}.
-The @code{dotglob} option is disabled when @env{GLOBIGNORE}
-is unset.
-
-@node Pattern Matching
-@subsubsection Pattern Matching
-@cindex pattern matching
-@cindex matching, pattern
-
-Any character that appears in a pattern, other than the special pattern
-characters described below, matches itself.
-The @sc{nul} character may not occur in a pattern.
-A backslash escapes the following character; the
-escaping backslash is discarded when matching.
-The special pattern characters must be quoted if they are to be matched
-literally.
-
-The special pattern characters have the following meanings:
-@table @code
-@item *
-Matches any string, including the null string.
-@item ?
-Matches any single character.
-@item [@dots{}]
-Matches any one of the enclosed characters.  A pair of characters
-separated by a hyphen denotes a @var{range expression};
-any character that sorts between those two characters, inclusive,
-using the current locale's collating sequence and character set,
-is matched.  If the first character following the
-@samp{[} is a @samp{!}  or a @samp{^}
-then any character not enclosed is matched.  A @samp{@minus{}}
-may be matched by including it as the first or last character
-in the set.  A @samp{]} may be matched by including it as the first
-character in the set.
-The sorting order of characters in range expressions is determined by
-the current locale and the value of the @env{LC_COLLATE} shell variable,
-if set.
-
-For example, in the default C locale, @samp{[a-dx-z]} is equivalent to
-@samp{[abcdxyz]}.  Many locales sort characters in dictionary order, and in
-these locales @samp{[a-dx-z]} is typically not equivalent to @samp{[abcdxyz]};
-it might be equivalent to @samp{[aBbCcDdxXyYz]}, for example.  To obtain
-the traditional interpretation of ranges in bracket expressions, you can
-force the use of the C locale by setting the @env{LC_COLLATE} or
-@env{LC_ALL} environment variable to the value @samp{C}.
-
-Within @samp{[} and @samp{]}, @var{character classes} can be specified
-using the syntax
-@code{[:}@var{class}@code{:]}, where @var{class} is one of the
-following classes defined in the @sc{posix} 1003.2 standard:
-@example
-alnum   alpha   ascii   blank   cntrl   digit   graph   lower
-print   punct   space   upper   word    xdigit
-@end example
-@noindent
-A character class matches any character belonging to that class.
-The @code{word} character class matches letters, digits, and the character
-@samp{_}.
-
-Within @samp{[} and @samp{]}, an @var{equivalence class} can be
-specified using the syntax @code{[=}@var{c}@code{=]}, which
-matches all characters with the same collation weight (as defined
-by the current locale) as the character @var{c}.
-
-Within @samp{[} and @samp{]}, the syntax @code{[.}@var{symbol}@code{.]}
-matches the collating symbol @var{symbol}.
-@end table
-
-If the @code{extglob} shell option is enabled using the @code{shopt}
-builtin, several extended pattern matching operators are recognized.
-In the following description, a @var{pattern-list} is a list of one
-or more patterns separated by a @samp{|}.
-Composite patterns may be formed using one or more of the following
-sub-patterns:
-
-@table @code
-@item ?(@var{pattern-list})
-Matches zero or one occurrence of the given patterns.
-
-@item *(@var{pattern-list})
-Matches zero or more occurrences of the given patterns.
-
-@item +(@var{pattern-list})
-Matches one or more occurrences of the given patterns.
-
-@item @@(@var{pattern-list})
-Matches exactly one of the given patterns.
-
-@item !(@var{pattern-list})
-Matches anything except one of the given patterns.
-@end table
-
-@node Quote Removal
-@subsection Quote Removal
-
-After the preceding expansions, all unquoted occurrences of the
-characters @samp{\}, @samp{'}, and @samp{"} that did not
-result from one of the above expansions are removed.
-
-@node Redirections
-@section Redirections
-@cindex redirection
-
-Before a command is executed, its input and output
-may be @var{redirected}
-using a special notation interpreted by the shell.
-Redirection may also be used to open and close files for the
-current shell execution environment.  The following redirection
-operators may precede or appear anywhere within a
-simple command or may follow a command.
-Redirections are processed in the order they appear, from
-left to right.
-
-In the following descriptions, if the file descriptor number is
-omitted, and the first character of the redirection operator is
-@samp{<}, the redirection refers to the standard input (file
-descriptor 0).  If the first character of the redirection operator
-is @samp{>}, the redirection refers to the standard output (file
-descriptor 1).
-
-The word following the redirection operator in the following
-descriptions, unless otherwise noted, is subjected to brace expansion,
-tilde expansion, parameter expansion, command substitution, arithmetic
-expansion, quote removal, filename 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
-@example
-ls > @var{dirlist} 2>&1
-@end example
-@noindent
-directs both standard output (file descriptor 1) and standard error
-(file descriptor 2) to the file @var{dirlist}, while the command
-@example
-ls 2>&1 > @var{dirlist}
-@end example
-@noindent
-directs only the standard output to file @var{dirlist},
-because the standard error was duplicated as standard output
-before the standard output was redirected to @var{dirlist}.
-
-Bash handles several filenames specially when they are used in
-redirections, as described in the following table:
-
-@table @code
-@item /dev/fd/@var{fd}
-If @var{fd} is a valid integer, file descriptor @var{fd} is duplicated.
-
-@item /dev/stdin
-File descriptor 0 is duplicated.
-
-@item /dev/stdout
-File descriptor 1 is duplicated.
-
-@item /dev/stderr
-File descriptor 2 is duplicated.
-
-@item /dev/tcp/@var{host}/@var{port}
-If @var{host} is a valid hostname or Internet address, and @var{port}
-is an integer port number or service name, Bash attempts to open a TCP
-connection to the corresponding socket.
-
-@item /dev/udp/@var{host}/@var{port}
-If @var{host} is a valid hostname or Internet address, and @var{port}
-is an integer port number or service name, Bash attempts to open a UDP
-connection to the corresponding socket.
-
-@end table
-
-A failure to open or create a file causes the redirection to fail.
-
-@subsection Redirecting Input
-Redirection of input causes the file whose name results from
-the expansion of @var{word}
-to be opened for reading on file descriptor @code{n},
-or the standard input (file descriptor 0) if @code{n}
-is not specified.
-
-The general format for redirecting input is:
-@example
-[@var{n}]<@var{word}
-@end example
-
-@subsection Redirecting Output
-Redirection of output causes the file whose name results from
-the expansion of @var{word}
-to be opened for writing on file descriptor @var{n},
-or the standard output (file descriptor 1) if @var{n}
-is not specified.  If the file does not exist it is created;
-if it does exist it is truncated to zero size.
-
-The general format for redirecting output is:
-@example
-[@var{n}]>[|]@var{word}
-@end example
-
-If the redirection operator is @samp{>}, and the @code{noclobber}
-option to the @code{set} builtin has been enabled, the redirection
-will fail if the file whose name results from the expansion of
-@var{word} exists and is a regular file.
-If the redirection operator is @samp{>|}, or the redirection operator is
-@samp{>} and the @code{noclobber} option is not enabled, the redirection
-is attempted even if the file named by @var{word} exists.
-
-@subsection Appending Redirected Output
-Redirection of output in this fashion
-causes the file whose name results from
-the expansion of @var{word}
-to be opened for appending on file descriptor @var{n},
-or the standard output (file descriptor 1) if @var{n}
-is not specified.  If the file does not exist it is created.
-
-The general format for appending output is:
-@example
-[@var{n}]>>@var{word}
-@end example
-
-@subsection 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 @var{word} with this construct.
-
-There are two formats for redirecting standard output and
-standard error:
-@example
-&>@var{word}
-@end example
-@noindent
-and
-@example
->&@var{word}
-@end example
-@noindent
-Of the two forms, the first is preferred.
-This is semantically equivalent to
-@example
->@var{word} 2>&1
-@end example
-
-@subsection Here Documents
-This type of redirection instructs the shell to read input from the
-current source until a line containing only @var{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:
-@example
-<<[@minus{}]@var{word}
-        @var{here-document}
-@var{delimiter}
-@end example
-
-No parameter expansion, command substitution, arithmetic expansion,
-or filename expansion is performed on
-@var{word}.  If any characters in @var{word} are quoted, the
-@var{delimiter} is the result of quote removal on @var{word},
-and the lines in the here-document are not expanded.
-If @var{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 @code{\newline} is ignored, and @samp{\}
-must be used to quote the characters
-@samp{\}, @samp{$}, and @samp{`}.
-
-If the redirection operator is @samp{<<-},
-then all leading tab characters are stripped from input lines and the
-line containing @var{delimiter}.
-This allows here-documents within shell scripts to be indented in a
-natural fashion.
-
-@subsection Here Strings
-A variant of here documents, the format is:
-@example
-<<< @var{word}
-@end example
-
-The @var{word} is expanded and supplied to the command on its standard
-input.
-
-@subsection Duplicating File Descriptors
-The redirection operator
-@example
-[@var{n}]<&@var{word}
-@end example
-@noindent
-is used to duplicate input file descriptors.
-If @var{word}
-expands to one or more digits, the file descriptor denoted by @var{n}
-is made to be a copy of that file descriptor.
-If the digits in @var{word} do not specify a file descriptor open for
-input, a redirection error occurs.
-If @var{word}
-evaluates to @samp{-}, file descriptor @var{n} is closed.  If
-@var{n} is not specified, the standard input (file descriptor 0) is used.
-
-The operator
-@example
-[@var{n}]>&@var{word}
-@end example
-@noindent
-is used similarly to duplicate output file descriptors.  If
-@var{n} is not specified, the standard output (file descriptor 1) is used.
-If the digits in @var{word} do not specify a file descriptor open for
-output, a redirection error occurs.
-As a special case, if @var{n} is omitted, and @var{word} does not
-expand to one or more digits, the standard output and standard
-error are redirected as described previously.
-
-@subsection Moving File Descriptors
-The redirection operator
-@example
-[@var{n}]<&@var{digit}-
-@end example
-@noindent
-moves the file descriptor @var{digit} to file descriptor @var{n},
-or the standard input (file descriptor 0) if @var{n} is not specified.
-@var{digit} is closed after being duplicated to @var{n}.
-
-Similarly, the redirection operator
-@example
-[@var{n}]>&@var{digit}-
-@end example
-@noindent
-moves the file descriptor @var{digit} to file descriptor @var{n},
-or the standard output (file descriptor 1) if @var{n} is not specified.
-
-@subsection Opening File Descriptors for Reading and Writing
-The redirection operator
-@example
-[@var{n}]<>@var{word}
-@end example
-@noindent
-causes the file whose name is the expansion of @var{word}
-to be opened for both reading and writing on file descriptor
-@var{n}, or on file descriptor 0 if @var{n}
-is not specified.  If the file does not exist, it is created.
-
-@node Executing Commands
-@section Executing Commands
-
-@menu
-* Simple Command Expansion::	How Bash expands simple commands before
-				executing them.
-
-* Command Search and Execution::	How Bash finds commands and runs them.
-
-* Command Execution Environment::	The environment in which Bash
-					executes commands that are not
-					shell builtins.
-
-* Environment::		The environment given to a command.
-
-* Exit Status::		The status returned by commands and how Bash
-			interprets it.
-
-* Signals::		What happens when Bash or a command it runs
-			receives a signal.
-
-@end menu
-
-@node Simple Command Expansion
-@subsection Simple Command Expansion
-@cindex command expansion
-
-When a simple command is executed, the shell performs the following
-expansions, assignments, and redirections, from left to right.
-
-@enumerate
-@item
-The words that the parser has marked as variable assignments (those
-preceding the command name) and redirections are saved for later
-processing.
-
-@item
-The words that are not variable assignments or redirections are
-expanded (@pxref{Shell Expansions}).
-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.
-
-@item
-Redirections are performed as described above (@pxref{Redirections}).
-
-@item
-The text after the @samp{=} in each variable assignment undergoes tilde
-expansion, parameter expansion, command substitution, arithmetic expansion,
-and quote removal before being assigned to the variable.
-@end enumerate
-
-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 status.
-
-If no command name results, redirections are performed, but do not
-affect the current shell environment.  A redirection error causes the
-command to exit with a non-zero status.
-
-If there is a command name left after expansion, execution proceeds as
-described below.  Otherwise, the command exits.  If one of the expansions
-contained a command substitution, the exit status of the command is
-the exit status of the last command substitution performed.  If there
-were no command substitutions, the command exits with a status of zero.
-
-@node Command Search and Execution
-@subsection Command Search and Execution
-@cindex command execution
-@cindex command search
-
-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.
-
-@enumerate
-@item
-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 in @ref{Shell Functions}.
-
-@item
-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.
-
-@item
-If the name is neither a shell function nor a builtin,
-and contains no slashes, Bash searches each element of
-@env{$PATH} for a directory containing an executable file
-by that name.  Bash uses a hash table to remember the full
-pathnames of executable files to avoid multiple @env{PATH} searches
-(see the description of @code{hash} in @ref{Bourne Shell Builtins}).
-A full search of the directories in @env{$PATH}
-is performed only if the command is not found in the hash table.
-If the search is unsuccessful, the shell prints an error
-message and returns an exit status of 127.
-
-@item
-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 supplied, if any.
-
-@item
-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
-@var{shell script} and the shell executes it as described in
-@ref{Shell Scripts}.
-
-@item
-If the command was not begun asynchronously, the shell waits for
-the command to complete and collects its exit status.
-
-@end enumerate
-
-@node Command Execution Environment
-@subsection Command Execution Environment
-@cindex execution environment
-
-The shell has an @var{execution environment}, which consists of the
-following:
-
-@itemize @bullet
-@item
-open files inherited by the shell at invocation, as modified by
-redirections supplied to the @code{exec} builtin
-
-@item
-the current working directory as set by @code{cd}, @code{pushd}, or
-@code{popd}, or inherited by the shell at invocation
-
-@item
-the file creation mode mask as set by @code{umask} or inherited from
-the shell's parent
-
-@item
-current traps set by @code{trap}
-
-@item
-shell parameters that are set by variable assignment or with @code{set}
-or inherited from the shell's parent in the environment
-
-@item
-shell functions defined during execution or inherited from the shell's
-parent in the environment
-
-@item
-options enabled at invocation (either by default or with command-line
-arguments) or by @code{set}
-
-@item
-options enabled by @code{shopt}
-
-@item
-shell aliases defined with @code{alias} (@pxref{Aliases})
-
-@item
-various process @sc{id}s, including those of background jobs
-(@pxref{Lists}), the value of @code{$$}, and the value of
-@env{$PPID}
-
-@end itemize
-
-When a simple command other than a builtin or shell function
-is to be executed, it
-is invoked in a separate execution environment that consists of
-the following.  Unless otherwise noted, the values are inherited
-from the shell.
-
-@itemize @bullet
-@item
-the shell's open files, plus any modifications and additions specified
-by redirections to the command
-
-@item
-the current working directory
-
-@item
-the file creation mode mask
-
-@item
-shell variables and functions marked for export, along with variables
-exported for the command, passed in the environment (@pxref{Environment})
-
-@item
-traps caught by the shell are reset to the values inherited from the
-shell's parent, and traps ignored by the shell are ignored
-
-@end itemize
-
-A command invoked in this separate environment cannot affect the
-shell's execution environment. 
-
-Command substitution, commands grouped with parentheses,
-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 @samp{&} and job control is not active, the
-default standard input for the command is the empty file @file{/dev/null}.
-Otherwise, the invoked command inherits the file descriptors of the calling
-shell as modified by redirections.
-
-@node Environment
-@subsection Environment
-@cindex environment
-
-When a program is invoked it is given an array of strings
-called the @var{environment}.
-This is a list of name-value pairs, of the form @code{name=value}.
-
-Bash provides several ways to manipulate the environment.
-On invocation, the shell scans its own environment and
-creates a parameter for each name found, automatically marking
-it for @var{export}
-to child processes.  Executed commands inherit the environment.
-The @code{export} and @samp{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 modified in the shell,
-less any pairs removed by the @code{unset} and @samp{export -n}
-commands, plus any additions via the @code{export} and
-@samp{declare -x} commands.
-
-The environment for any simple command
-or function may be augmented temporarily by prefixing it with
-parameter assignments, as described in @ref{Shell Parameters}.
-These assignment statements affect only the environment seen
-by that command.
-
-If the @option{-k} option is set (@pxref{The Set Builtin}), then all
-parameter assignments are placed in the environment for a command,
-not just those that precede the command name.
-
-When Bash invokes an external command, the variable @samp{$_}
-is set to the full path name of the command and passed to that
-command in its environment.
-
-@node Exit Status
-@subsection Exit Status
-@cindex exit status
-
-For the shell's purposes, a command which exits with a
-zero exit status has succeeded.
-A non-zero exit status indicates failure.
-This seemingly counter-intuitive scheme is used so there
-is one well-defined way to indicate success and a variety of
-ways to indicate various failure modes.
-When a command terminates on a fatal signal whose number is @var{N},
-Bash uses the value 128+@var{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.
-
-The exit status is used by the Bash conditional commands
-(@pxref{Conditional Constructs}) and some of the list
-constructs (@pxref{Lists}).
-
-All of the Bash builtins return an exit status of zero if they succeed
-and a non-zero status on failure, so they may be used by the
-conditional and list constructs.
-All builtins return an exit status of 2 to indicate incorrect usage.
-
-@node Signals
-@subsection Signals
-@cindex signal handling
-
-When Bash is interactive, in the absence of any traps, it ignores
-@code{SIGTERM} (so that @samp{kill 0} does not kill an interactive shell),
-and @code{SIGINT}
-is caught and handled (so that the @code{wait} builtin is interruptible).
-When Bash receives a @code{SIGINT}, it breaks out of any executing loops.
-In all cases, Bash ignores @code{SIGQUIT}.
-If job control is in effect (@pxref{Job Control}), Bash
-ignores @code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}.
-
-Non-builtin commands 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 @code{SIGINT} and @code{SIGQUIT} in addition to these inherited
-handlers.
-Commands run as a result of
-command substitution ignore the keyboard-generated job control signals
-@code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}.
-
-The shell exits by default upon receipt of a @code{SIGHUP}.
-Before exiting, an interactive shell resends the @code{SIGHUP} to
-all jobs, running or stopped.
-Stopped jobs are sent @code{SIGCONT} to ensure that they receive
-the @code{SIGHUP}.
-To prevent the shell from sending the @code{SIGHUP} signal to a
-particular job, it should be removed
-from the jobs table with the @code{disown}
-builtin (@pxref{Job Control Builtins}) or marked
-to not receive @code{SIGHUP} using @code{disown -h}.
-
-If the  @code{huponexit} shell option has been set with @code{shopt}
-(@pxref{Bash Builtins}), Bash sends a @code{SIGHUP} to all jobs when
-an interactive login shell exits.
-
-If Bash is waiting for a command to complete and receives a signal
-for which a trap has been set, the trap will not be executed until
-the command completes. 
-When Bash is waiting for an asynchronous
-command via the @code{wait} builtin, the reception of a signal for
-which a trap has been set will cause the @code{wait} builtin to return
-immediately with an exit status greater than 128, immediately after
-which the trap is executed.
-
-@node Shell Scripts
-@section Shell Scripts
-@cindex shell script
-
-A shell script is a text file containing shell commands.  When such
-a file is used as the first non-option argument when invoking Bash,
-and neither the @option{-c} nor @option{-s} option is supplied
-(@pxref{Invoking Bash}), 
-Bash reads and executes commands from the file, then exits.  This
-mode of operation creates a non-interactive shell.  The shell first
-searches for the file in the current directory, and looks in the
-directories in @env{$PATH} if not found there.
-
-When Bash runs
-a shell script, it sets the special parameter @code{0} to the name
-of the file, rather than the name of the shell, and the positional
-parameters are set to the remaining arguments, if any are given.
-If no additional arguments are supplied, the positional parameters
-are unset.
-
-A shell script may be made executable by using the @code{chmod} command
-to turn on the execute bit.  When Bash finds such a file while
-searching the @env{$PATH} for a command, it spawns a subshell to
-execute it.  In other words, executing
-@example
-filename @var{arguments}
-@end example
-@noindent
-is equivalent to executing
-@example
-bash filename @var{arguments}
-@end example
-
-@noindent
-if @code{filename} is an executable shell script.
-This subshell reinitializes itself, so that the effect is as if a
-new shell had been invoked to interpret the script, with the
-exception that the locations of commands remembered by the parent
-(see the description of @code{hash} in @ref{Bourne Shell Builtins})
-are retained by the child.
-
-Most versions of Unix make this a part of the operating system's command
-execution mechanism.  If the first line of a script begins with
-the two characters @samp{#!}, the remainder of the line specifies
-an interpreter for the program.
-Thus, you can specify Bash, @code{awk}, Perl, or some other
-interpreter and write the rest of the script file in that language.
-
-The arguments to the interpreter
-consist of a single optional argument following the interpreter
-name on the first line of the script file, followed by the name of
-the script file, followed by the rest of the arguments.  Bash
-will perform this action on operating systems that do not handle it
-themselves.  Note that some older versions of Unix limit the interpreter
-name and argument to a maximum of 32 characters.
-
-Bash scripts often begin with @code{#! /bin/bash} (assuming that
-Bash has been installed in @file{/bin}), since this ensures that
-Bash will be used to interpret the script, even if it is executed
-under another shell.
-
-@node Shell Builtin Commands
-@chapter Shell Builtin Commands
-
-@menu
-* Bourne Shell Builtins::	Builtin commands inherited from the Bourne
-				Shell.
-* Bash Builtins::		Table of builtins specific to Bash.
-* The Set Builtin::		This builtin is so overloaded it
-				deserves its own section.
-* Special Builtins::		Builtin commands classified specially by
-				POSIX.2.
-@end menu
-
-Builtin commands are contained within the shell itself.
-When the name of a builtin command is used as the first word of
-a simple command (@pxref{Simple Commands}), the shell executes
-the command directly, without invoking another program.
-Builtin commands are necessary to implement functionality impossible
-or inconvenient to obtain with separate utilities.
-
-This section briefly the builtins which Bash inherits from
-the Bourne Shell, as well as the builtin commands which are unique
-to or have been extended in Bash.
-
-Several builtin commands are described in other chapters:  builtin
-commands which provide the Bash interface to the job control
-facilities (@pxref{Job Control Builtins}), the directory stack
-(@pxref{Directory Stack Builtins}), the command history
-(@pxref{Bash History Builtins}), and the programmable completion
-facilities (@pxref{Programmable Completion Builtins}).
-
-Many of the builtins have been extended by @sc{posix} or Bash.
-
-Unless otherwise noted, each builtin command documented as accepting
-options preceded by @samp{-} accepts @samp{--}
-to signify the end of the options.
-
-@node Bourne Shell Builtins
-@section Bourne Shell Builtins
-
-The following shell builtin commands are inherited from the Bourne Shell.
-These commands are implemented as specified by the @sc{posix} 1003.2 standard.
-
-@table @code
-@item :    @r{(a colon)}
-@btindex :
-@example
-: [@var{arguments}]
-@end example
-Do nothing beyond expanding @var{arguments} and performing redirections.
-The return status is zero.
-
-@item .    @r{(a period)}
-@btindex .
-@example
-. @var{filename} [@var{arguments}]
-@end example
-Read and execute commands from the @var{filename} argument in the
-current shell context.  If @var{filename} does not contain a slash,
-the @env{PATH} variable is used to find @var{filename}.
-When Bash is not in @sc{posix} mode, the current directory is searched
-if @var{filename} is not found in @env{$PATH}.
-If any @var{arguments} are supplied, they become the positional
-parameters when @var{filename} is executed.  Otherwise the positional
-parameters are unchanged.
-The return status is the exit status of the last command executed, or
-zero if no commands are executed.  If @var{filename} is not found, or
-cannot be read, the return status is non-zero.
-This builtin is equivalent to @code{source}.
-
-@item break
-@btindex break
-@example
-break [@var{n}]
-@end example
-Exit from a @code{for}, @code{while}, @code{until}, or @code{select} loop.
-If @var{n} is supplied, the @var{n}th enclosing loop is exited.
-@var{n} must be greater than or equal to 1.
-The return status is zero unless @var{n} is not greater than or equal to 1.
-
-@item cd
-@btindex cd
-@example
-cd [-L|-P] [@var{directory}]
-@end example
-Change the current working directory to @var{directory}.
-If @var{directory} is not given, the value of the @env{HOME} shell
-variable is used.
-If the shell variable @env{CDPATH} exists, it is used as a search path.
-If @var{directory} begins with a slash, @env{CDPATH} is not used.
-
-The @option{-P} option means to not follow symbolic links; symbolic
-links are followed by default or with the @option{-L} option.
-If @var{directory} is @samp{-}, it is equivalent to @env{$OLDPWD}.
-
-If a non-empty directory name from @env{CDPATH} is used, or if
-@samp{-} is the first argument, and the directory change is
-successful, the absolute pathname of the new working directory is
-written to the standard output.
-
-The return status is zero if the directory is successfully changed,
-non-zero otherwise.
-
-@item continue
-@btindex continue
-@example
-continue [@var{n}]
-@end example
-Resume the next iteration of an enclosing @code{for}, @code{while},
-@code{until}, or @code{select} loop.
-If @var{n} is supplied, the execution of the @var{n}th enclosing loop
-is resumed.
-@var{n} must be greater than or equal to 1.
-The return status is zero unless @var{n} is not greater than or equal to 1.
-
-@item eval
-@btindex eval
-@example
-eval [@var{arguments}]
-@end example
-The arguments are concatenated together into a single command, which is
-then read and executed, and its exit status returned as the exit status
-of @code{eval}.
-If there are no arguments or only empty arguments, the return status is
-zero.
-
-@item exec
-@btindex exec
-@example
-exec [-cl] [-a @var{name}] [@var{command} [@var{arguments}]]
-@end example
-If @var{command}
-is supplied, it replaces the shell without creating a new process.
-If the @option{-l} option is supplied, the shell places a dash at the
-beginning of the zeroth arg passed to @var{command}.
-This is what the @code{login} program does.
-The @option{-c} option causes @var{command} to be executed with an empty
-environment.
-If @option{-a} is supplied, the shell passes @var{name} as the zeroth
-argument to @var{command}.
-If no @var{command} is specified, redirections may be used to affect
-the current shell environment.  If there are no redirection errors, the
-return status is zero; otherwise the return status is non-zero.
-
-@item exit
-@btindex exit
-@example
-exit [@var{n}]
-@end example
-Exit the shell, returning a status of @var{n} to the shell's parent.
-If @var{n} is omitted, the exit status is that of the last command executed.
-Any trap on @code{EXIT} is executed before the shell terminates.
-
-@item export
-@btindex export
-@example
-export [-fn] [-p] [@var{name}[=@var{value}]]
-@end example
-Mark each @var{name} to be passed to child processes
-in the environment.  If the @option{-f} option is supplied, the @var{name}s
-refer to shell functions; otherwise the names refer to shell variables.
-The @option{-n} option means to no longer mark each @var{name} for export.
-If no @var{names} are supplied, or if the @option{-p} option is given, a
-list of exported names is displayed.
-The @option{-p} option displays output in a form that may be reused as input.
-If a variable name is followed by =@var{value}, the value of
-the variable is set to @var{value}.
-
-The return status is zero unless an invalid option is supplied, one of
-the names is not a valid shell variable name, or @option{-f} is supplied
-with a name that is not a shell function.
-
-@item getopts
-@btindex getopts
-@example
-getopts @var{optstring} @var{name} [@var{args}]
-@end example
-@code{getopts} is used by shell scripts to parse positional parameters.
-@var{optstring} contains the option characters to be recognized; if a
-character is followed by a colon, the option is expected to have an
-argument, which should be separated from it by white space.
-The colon (@samp{:}) and question mark (@samp{?}) may not be
-used as option characters.
-Each time it is invoked, @code{getopts}
-places the next option in the shell variable @var{name}, initializing
-@var{name} if it does not exist,
-and the index of the next argument to be processed into the
-variable @env{OPTIND}.
-@env{OPTIND} is initialized to 1 each time the shell or a shell script
-is invoked.
-When an option requires an argument,
-@code{getopts} places that argument into the variable @env{OPTARG}.
-The shell does not reset @env{OPTIND} automatically; it must be manually
-reset between multiple calls to @code{getopts} within the same shell
-invocation if a new set of parameters is to be used.
-
-When the end of options is encountered, @code{getopts} exits with a
-return value greater than zero.
-@env{OPTIND} is set to the index of the first non-option argument,
-and @code{name} is set to @samp{?}.
-
-@code{getopts}
-normally parses the positional parameters, but if more arguments are
-given in @var{args}, @code{getopts} parses those instead.
-
-@code{getopts} can report errors in two ways.  If the first character of
-@var{optstring} is a colon, @var{silent}
-error reporting is used.  In normal operation diagnostic messages
-are printed when invalid options or missing option arguments are
-encountered.
-If the variable @env{OPTERR}
-is set to 0, no error messages will be displayed, even if the first
-character of @code{optstring} is not a colon.
-
-If an invalid option is seen,
-@code{getopts} places @samp{?} into @var{name} and, if not silent,
-prints an error message and unsets @env{OPTARG}.
-If @code{getopts} is silent, the option character found is placed in
-@env{OPTARG} and no diagnostic message is printed.
-
-If a required argument is not found, and @code{getopts}
-is not silent, a question mark (@samp{?}) is placed in @var{name},
-@code{OPTARG} is unset, and a diagnostic message is printed.
-If @code{getopts} is silent, then a colon (@samp{:}) is placed in
-@var{name} and @env{OPTARG} is set to the option character found.
-
-@item hash
-@btindex hash
-@example
-hash [-'r] [-p @var{filename}] [-dt] [@var{name}]
-@end example
-Remember the full pathnames of commands specified as @var{name} arguments,
-so they need not be searched for on subsequent invocations.
-The commands are found by searching through the directories listed in
-@env{$PATH}.
-The @option{-p} option inhibits the path search, and @var{filename} is
-used as the location of @var{name}.
-The @option{-r} option causes the shell to forget all remembered locations.
-The @option{-d} option causes the shell to forget the remembered location
-of each @var{name}.
-If the @option{-t} option is supplied, the full pathname to which each
-@var{name} corresponds is printed.  If multiple @var{name} arguments are
-supplied with @option{-t} the @var{name} is printed before the hashed
-full pathname.
-The @option{-l} option causes output to be displayed in a format
-that may be reused as input.
-If no arguments are given, or if only @option{-l} is supplied,
-information about remembered commands is printed.
-The return status is zero unless a @var{name} is not found or an invalid
-option is supplied.
-
-@item pwd
-@btindex pwd
-@example
-pwd [-LP]
-@end example
-Print the absolute pathname of the current working directory.
-If the @option{-P} option is supplied, the pathname printed will not
-contain symbolic links.
-If the @option{-L} option is supplied, the pathname printed may contain
-symbolic links.
-The return status is zero unless an error is encountered while
-determining the name of the current directory or an invalid option
-is supplied.
-
-@item readonly
-@btindex readonly
-@example
-readonly [-apf] [@var{name}[=@var{value}]] @dots{}
-@end example
-Mark each @var{name} as readonly.
-The values of these names may not be changed by subsequent assignment.
-If the @option{-f} option is supplied, each @var{name} refers to a shell
-function.
-The @option{-a} option means each @var{name} refers to an array variable.
-If no @var{name} arguments are given, or if the @option{-p}
-option is supplied, a list of all readonly names is printed.
-The @option{-p} option causes output to be displayed in a format that
-may be reused as input.
-If a variable name is followed by =@var{value}, the value of
-the variable is set to @var{value}.
-The return status is zero unless an invalid option is supplied, one of
-the @var{name} arguments is not a valid shell variable or function name,
-or the @option{-f} option is supplied with a name that is not a shell function.
-
-@item return
-@btindex return
-@example
-return [@var{n}]
-@end example
-Cause a shell function to exit with the return value @var{n}.
-If @var{n} is not supplied, the return value is the exit status of the
-last command executed in the function.
-This may also be used to terminate execution of a script being executed
-with the @code{.} (or @code{source}) builtin, returning either @var{n} or
-the exit status of the last command executed within the script as the exit
-status of the script.
-Any command associated with the @code{RETURN} trap is executed
-before execution resumes after the function or script.
-The return status is non-zero if @code{return} is used outside a function
-and not during the execution of a script by @code{.} or @code{source}.
-
-@item shift
-@btindex shift
-@example
-shift [@var{n}]
-@end example
-Shift the positional parameters to the left by @var{n}.
-The positional parameters from @var{n}+1 @dots{} @code{$#} are
-renamed to @code{$1} @dots{} @code{$#}-@var{n}+1.
-Parameters represented by the numbers @code{$#} to @var{n}+1 are unset.
-@var{n} must be a non-negative number less than or equal to @code{$#}.
-If @var{n} is zero or greater than @code{$#}, the positional parameters
-are not changed.
-If @var{n} is not supplied, it is assumed to be 1.
-The return status is zero unless @var{n} is greater than @code{$#} or
-less than zero, non-zero otherwise.
-
-@item test
-@itemx [
-@btindex test
-@btindex [
-Evaluate a conditional expression @var{expr}.
-Each operator and operand must be a separate argument.
-Expressions are composed of the primaries described below in
-@ref{Bash Conditional Expressions}.
-
-When the @code{[} form is used, the last argument to the command must
-be a @code{]}.
-
-Expressions may be combined using the following operators, listed in
-decreasing order of precedence.
-
-@table @code
-@item ! @var{expr}
-True if @var{expr} is false.
-
-@item ( @var{expr} )
-Returns the value of @var{expr}.
-This may be used to override the normal precedence of operators.
-
-@item @var{expr1} -a @var{expr2}
-True if both @var{expr1} and @var{expr2} are true.
-
-@item @var{expr1} -o @var{expr2}
-True if either @var{expr1} or @var{expr2} is true.
-@end table
-
-The @code{test} and @code{[} builtins evaluate conditional
-expressions using a set of rules based on the number of arguments.
-
-@table @asis
-@item 0 arguments
-The expression is false.
-
-@item 1 argument
-The expression is true if and only if the argument is not null.
-
-@item 2 arguments
-If the first argument is @samp{!}, the expression is true if and
-only if the second argument is null.
-If the first argument is one of the unary conditional operators
-(@pxref{Bash Conditional Expressions}), the expression
-is true if the unary test is true.
-If the first argument is not a valid unary operator, the expression is
-false.
-
-@item 3 arguments
-If the second argument is one of the binary conditional
-operators (@pxref{Bash 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 @samp{!}, the value is the negation of
-the two-argument test using the second and third arguments.
-If the first argument is exactly @samp{(} and the third argument is
-exactly @samp{)}, the result is the one-argument test of the second
-argument.
-Otherwise, the expression is false.
-The @samp{-a} and @samp{-o} operators are considered binary operators
-in this case.  
-
-@item 4 arguments
-If the first argument is @samp{!}, 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.
-
-@item 5 or more arguments
-The expression is parsed and evaluated according to precedence
-using the rules listed above.
-@end table
-
-@item times
-@btindex times
-@example
-times
-@end example
-Print out the user and system times used by the shell and its children.
-The return status is zero.
-
-@item trap
-@btindex trap
-@example
-trap [-lp] [@var{arg}] [@var{sigspec} @dots{}]
-@end example
-The commands in @var{arg} are to be read and executed when the
-shell receives signal @var{sigspec}.  If @var{arg} is absent (and
-there is a single @var{sigspec}) or
-equal to @samp{-}, each specified signal's disposition is reset
-to the value it had when the shell was started.
-If @var{arg} is the null string, then the signal specified by
-each @var{sigspec} is ignored by the shell and commands it invokes.
-If @var{arg} is not present and @option{-p} has been supplied,
-the shell displays the trap commands associated with each @var{sigspec}.
-If no arguments are supplied, or
-only @option{-p} is given, @code{trap} prints the list of commands
-associated with each signal number in a form that may be reused as
-shell input.
-The @option{-l} option causes the shell to print a list of signal names
-and their corresponding numbers.
-Each @var{sigspec} is either a signal name or a signal number.
-Signal names are case insensitive and the @code{SIG} prefix is optional.
-If a @var{sigspec}
-is @code{0} or @code{EXIT}, @var{arg} is executed when the shell exits.
-If a @var{sigspec} is @code{DEBUG}, the command @var{arg} is executed
-before every simple command, @code{for} command, @code{case} command,
-@code{select} command, every arithmetic @code{for} command, and before
-the first command executes in a shell function.
-Refer to the description of the @code{extglob} option to the
-@code{shopt} builtin (@pxref{Bash Builtins}) for details of its
-effect on the @code{DEBUG} trap.
-If a @var{sigspec} is @code{ERR}, the command @var{arg} 
-is executed whenever a simple command has a non-zero exit status,
-subject to the following conditions.
-The @code{ERR} trap is not executed if the failed command is part of the
-command list immediately following an @code{until} or @code{while} keyword,
-part of the test in an @code{if} statement,
-part of a @code{&&} or @code{||} list, or if the command's return
-status is being inverted using @code{!}.
-These are the same conditions obeyed by the @code{errexit} option.
-If a @var{sigspec} is @code{RETURN}, the command @var{arg} is executed
-each time a shell function or a script executed with the @code{.} or
-@code{source} builtins finishes executing.
-
-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 zero unless a @var{sigspec} does not specify a
-valid signal.
-
-@item umask
-@btindex umask
-@example
-umask [-p] [-S] [@var{mode}]
-@end example
-Set the shell process's file creation mask to @var{mode}.  If
-@var{mode} begins with a digit, it is interpreted as an octal number;
-if not, it is interpreted as a symbolic mode mask similar
-to that accepted by the @code{chmod} command.  If @var{mode} is
-omitted, the current value of the mask is printed.  If the @option{-S}
-option is supplied without a @var{mode} argument, the mask is printed
-in a symbolic format.
-If the  @option{-p} option is supplied, and @var{mode}
-is omitted, the output is in a form that may be reused as input.
-The return status is zero if the mode is successfully changed or if
-no @var{mode} argument is supplied, and non-zero otherwise.
-
-Note that when the mode is interpreted as an octal number, each number
-of the umask is subtracted from @code{7}.  Thus, a umask of @code{022}
-results in permissions of @code{755}.
-
-@item unset
-@btindex unset
-@example
-unset [-fv] [@var{name}]
-@end example
-Each variable or function @var{name} is removed.
-If no options are supplied, or the @option{-v} option is given, each
-@var{name} refers to a shell variable. 
-If the @option{-f} option is given, the @var{name}s refer to shell
-functions, and the function definition is removed.
-Readonly variables and functions may not be unset.
-The return status is zero unless a @var{name} is readonly.
-@end table
-
-@node Bash Builtins
-@section Bash Builtin Commands
-
-This section describes builtin commands which are unique to
-or have been extended in Bash.
-Some of these commands are specified in the @sc{posix} 1003.2 standard.
-
-@table @code
-
-@item alias
-@btindex alias
-@example
-alias [@code{-p}] [@var{name}[=@var{value}] @dots{}]
-@end example
-
-Without arguments or with the @option{-p} option, @code{alias} prints
-the list of aliases on the standard output in a form that allows
-them to be reused as input.
-If arguments are supplied, an alias is defined for each @var{name}
-whose @var{value} is given.  If no @var{value} is given, the name
-and value of the alias is printed.
-Aliases are described in @ref{Aliases}.
-
-@item bind
-@btindex bind
-@example
-bind [-m @var{keymap}] [-lpsvPSV]
-bind [-m @var{keymap}] [-q @var{function}] [-u @var{function}] [-r @var{keyseq}]
-bind [-m @var{keymap}] -f @var{filename}
-bind [-m @var{keymap}] -x @var{keyseq:shell-command}
-bind [-m @var{keymap}] @var{keyseq:function-name}
-bind @var{readline-command}
-@end example
-
-Display current Readline (@pxref{Command Line Editing})
-key and function bindings,
-bind a key sequence to a Readline function or macro,
-or set a Readline variable.
-Each non-option argument is a command as it would appear in a
-a Readline initialization file (@pxref{Readline Init File}),
-but each binding or command must be passed as a separate argument;  e.g.,
-@samp{"\C-x\C-r":re-read-init-file}.
-Options, if supplied, have the following meanings:
-
-@table @code
-@item -m @var{keymap}
-Use @var{keymap} as the keymap to be affected by
-the subsequent bindings.  Acceptable @var{keymap}
-names are
-@code{emacs},
-@code{emacs-standard},
-@code{emacs-meta},
-@code{emacs-ctlx},
-@code{vi},
-@code{vi-move},
-@code{vi-command}, and
-@code{vi-insert}.
-@code{vi} is equivalent to @code{vi-command};
-@code{emacs} is equivalent to @code{emacs-standard}.
-
-@item -l
-List the names of all Readline functions.
-
-@item -p
-Display Readline function names and bindings in such a way that they
-can be used as input or in a Readline initialization file.
-
-@item -P
-List current Readline function names and bindings.
-
-@item -v
-Display Readline variable names and values in such a way that they
-can be used as input or in a Readline initialization file.
-
-@item -V
-List current Readline variable names and values.
-
-@item -s
-Display Readline key sequences bound to macros and the strings they output
-in such a way that they can be used as input or in a Readline
-initialization file.
-
-@item -S
-Display Readline key sequences bound to macros and the strings they output.
-
-@item -f @var{filename}
-Read key bindings from @var{filename}.
-
-@item -q @var{function}
-Query about which keys invoke the named @var{function}.
-
-@item -u @var{function}
-Unbind all keys bound to the named @var{function}.
-
-@item -r @var{keyseq}
-Remove any current binding for @var{keyseq}.
-
-@item -x @var{keyseq:shell-command}
-Cause @var{shell-command} to be executed whenever @var{keyseq} is
-entered.
-
-@end table
-
-@noindent
-The return status is zero unless an invalid option is supplied or an
-error occurs.
-
-@item builtin
-@btindex builtin
-@example
-builtin [@var{shell-builtin} [@var{args}]]
-@end example
-Run a shell builtin, passing it @var{args}, and return its exit status.
-This is useful when defining a shell function with the same
-name as a shell builtin, retaining the functionality of the builtin within
-the function.
-The return status is non-zero if @var{shell-builtin} is not a shell
-builtin command.
-
-@item caller
-@btindex caller
-@example
-caller [@var{expr}]
-@end example
-Returns the context of any active subroutine call (a shell function or
-a script executed with the @code{.} or @code{source} builtins).
-
-Without @var{expr}, @code{caller} displays the line number and source
-filename of the current subroutine call.
-If a non-negative integer is supplied as @var{expr}, @code{caller} 
-displays the line number, subroutine name, and source file corresponding
-to that position in the current execution call stack.  This extra
-information may be used, for example, to print a stack trace.  The
-current frame is frame 0.
-
-The return value is 0 unless the shell is not executing a subroutine
-call or @var{expr} does not correspond to a valid position in the
-call stack.
-
-@item command
-@btindex command
-@example
-command [-pVv] @var{command} [@var{arguments} @dots{}]
-@end example
-Runs @var{command} with @var{arguments} ignoring any shell function
-named @var{command}.
-Only shell builtin commands or commands found by searching the
-@env{PATH} are executed.
-If there is a shell function named @code{ls}, running @samp{command ls}
-within the function will execute the external command @code{ls}
-instead of calling the function recursively.
-The @option{-p} option means to use a default value for @env{PATH}
-that is guaranteed to find all of the standard utilities.
-The return status in this case is 127 if @var{command} cannot be
-found or an error occurred, and the exit status of @var{command}
-otherwise.
-
-If either the @option{-V} or @option{-v} option is supplied, a
-description of @var{command} is printed.  The @option{-v} option
-causes a single word indicating the command or file name used to
-invoke @var{command} to be displayed; the @option{-V} option produces
-a more verbose description.  In this case, the return status is
-zero if @var{command} is found, and non-zero if not.
-
-@item declare
-@btindex declare
-@example
-declare [-afFirtx] [-p] [@var{name}[=@var{value}] @dots{}]
-@end example
-
-Declare variables and give them attributes.  If no @var{name}s
-are given, then display the values of variables instead. 
-
-The @option{-p} option will display the attributes and values of each
-@var{name}.
-When @option{-p} is used, additional options are ignored.
-The @option{-F} option inhibits the display of function definitions;
-only the function name and attributes are printed.
-If the @code{extdebug} shell option is enabled using @code{shopt}
-(@pxref{Bash Builtins}), the source file name and line number where
-the function is defined are displayed as well.
-@option{-F} implies @option{-f}.
-The following options can be used to restrict output to variables with
-the specified attributes or to give variables attributes:
-
-@table @code
-@item -a
-Each @var{name} is an array variable (@pxref{Arrays}).
-
-@item -f
-Use function names only.
-
-@item -i
-The variable is to be treated as
-an integer; arithmetic evaluation (@pxref{Shell Arithmetic}) is
-performed when the variable is assigned a value.
-
-@item -r
-Make @var{name}s readonly.  These names cannot then be assigned values
-by subsequent assignment statements or unset.
-
-@item -t
-Give each @var{name} the @code{trace} attribute.
-Traced functions inherit the @code{DEBUG} trap from the calling shell.
-The trace attribute has no special meaning for variables.
-
-@item -x
-Mark each @var{name} for export to subsequent commands via
-the environment.
-@end table
-
-Using @samp{+} instead of @samp{-} turns off the attribute instead.
-When used in a function, @code{declare} makes each @var{name} local,
-as with the @code{local} command.  If a variable name is followed by
-=@var{value}, the value of the variable is set to @var{value}.
-
-The return status is zero unless an invalid option is encountered,
-an attempt is made to define a function using @samp{-f foo=bar},
-an attempt is made to assign a value to a readonly variable,
-an attempt is made to assign a value to an array variable without
-using the compound assignment syntax (@pxref{Arrays}),
-one of the @var{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 @option{-f}.
-
-@item echo
-@btindex echo
-@example
-echo [-neE] [@var{arg} @dots{}]
-@end example
-Output the @var{arg}s, separated by spaces, terminated with a
-newline.
-The return status is always 0.
-If @option{-n} is specified, the trailing newline is suppressed.
-If the @option{-e} option is given, interpretation of the following
-backslash-escaped characters is enabled.
-The @option{-E} option disables the interpretation of these escape characters,
-even on systems where they are interpreted by default.
-The @code{xpg_echo} shell option may be used to
-dynamically determine whether or not @code{echo} expands these
-escape characters by default.
-@code{echo} interprets the following escape sequences:
-@table @code
-@item \a
-alert (bell)
-@item \b
-backspace
-@item \c
-suppress trailing newline
-@item \e
-escape
-@item \f
-form feed
-@item \n
-new line
-@item \r
-carriage return
-@item \t 
-horizontal tab
-@item \v
-vertical tab
-@item \\
-backslash
-@item \0@var{nnn}
-the eight-bit character whose value is the octal value @var{nnn}
-(zero to three octal digits)
-@item \@var{nnn}
-the eight-bit character whose value is the octal value @var{nnn}
-(one to three octal digits)
-@item \x@var{HH}
-the eight-bit character whose value is the hexadecimal value @var{HH}
-(one or two hex digits)
-@end table
-
-@item enable
-@btindex enable
-@example
-enable [-n] [-p] [-f @var{filename}] [-ads] [@var{name} @dots{}]
-@end example
-Enable and disable builtin shell commands.
-Disabling a builtin allows a disk command which has the same name
-as a shell builtin to be executed without specifying a full pathname,
-even though the shell normally searches for builtins before disk commands.
-If @option{-n} is used, the @var{name}s become disabled.  Otherwise
-@var{name}s are enabled.  For example, to use the @code{test} binary
-found via @env{$PATH} instead of the shell builtin version, type
-@samp{enable -n test}.
-
-If the @option{-p} option is supplied, or no @var{name} arguments appear,
-a list of shell builtins is printed.  With no other arguments, the list
-consists of all enabled shell builtins.
-The @option{-a} option means to list
-each builtin with an indication of whether or not it is enabled. 
-
-The @option{-f} option means to load the new builtin command @var{name}
-from shared object @var{filename}, on systems that support dynamic loading.
-The @option{-d} option will delete a builtin loaded with @option{-f}.
-
-If there are no options, a list of the shell builtins is displayed.
-The @option{-s} option restricts @code{enable} to the @sc{posix} special
-builtins.  If @option{-s} is used with @option{-f}, the new builtin becomes
-a special builtin (@pxref{Special Builtins}).
-
-The return status is zero unless a @var{name} is not a shell builtin
-or there is an error loading a new builtin from a shared object.
-
-@item help
-@btindex help
-@example
-help [-s] [@var{pattern}]
-@end example
-Display helpful information about builtin commands.
-If @var{pattern} is specified, @code{help} gives detailed help
-on all commands matching @var{pattern}, otherwise a list of
-the builtins is printed.
-The @option{-s} option restricts the information displayed to a short
-usage synopsis.
-The return status is zero unless no command matches @var{pattern}.
-
-@item let
-@btindex let
-@example
-let @var{expression} [@var{expression}]
-@end example
-The @code{let} builtin allows arithmetic to be performed on shell
-variables.  Each @var{expression} is evaluated according to the
-rules given below in @ref{Shell Arithmetic}.  If the
-last @var{expression} evaluates to 0, @code{let} returns 1;
-otherwise 0 is returned.
-
-@item local
-@btindex local
-@example
-local [@var{option}] @var{name}[=@var{value}] @dots{}
-@end example
-For each argument, a local variable named @var{name} is created,
-and assigned @var{value}.
-The @var{option} can be any of the options accepted by @code{declare}.
-@code{local} can only be used within a function; it makes the variable
-@var{name} have a visible scope restricted to that function and its
-children.  The return status is zero unless @code{local} is used outside
-a function, an invalid @var{name} is supplied, or @var{name} is a
-readonly variable.
-
-@item logout
-@btindex logout
-@example
-logout [@var{n}]
-@end example
-Exit a login shell, returning a status of @var{n} to the shell's
-parent.
-
-@item printf
-@btindex printf
-@example
-@code{printf} @var{format} [@var{arguments}]
-@end example
-Write the formatted @var{arguments} to the standard output under the
-control of the @var{format}.
-The @var{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
-@var{argument}.
-In addition to the standard @code{printf(1)} formats, @samp{%b} causes
-@code{printf} to expand backslash escape sequences in the corresponding
-@var{argument},
-(except that @samp{\c} terminates output, backslashes in
-@samp{\'}, @samp{\"}, and @samp{\?} are not removed, and octal escapes
-beginning with @samp{\0} may contain up to four digits),
-and @samp{%q} causes @code{printf} to output the
-corresponding @var{argument} in a format that can be reused as shell input.
-
-The @var{format} is reused as necessary to consume all of the @var{arguments}.
-If the @var{format} requires more @var{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.
-
-@item read
-@btindex read
-@example
-read [-ers] [-a @var{aname}] [-d @var{delim}] [-n @var{nchars}] [-p @var{prompt}] [-t @var{timeout}] [-u @var{fd}] [@var{name} @dots{}]
-@end example
-One line is read from the standard input, or from the file descriptor
-@var{fd} supplied as an argument to the @option{-u} option, and the first word
-is assigned to the first @var{name}, the second word to the second @var{name},
-and so on, with leftover words and their intervening separators assigned
-to the last @var{name}.
-If there are fewer words read from the input stream than names,
-the remaining names are assigned empty values.
-The characters in the value of the @env{IFS} variable
-are used to split the line into words.
-The backslash character @samp{\} may be used to remove any special
-meaning for the next character read and for line continuation.
-If no names are supplied, the line read is assigned to the
-variable @env{REPLY}.
-The return code is zero, unless end-of-file is encountered, @code{read}
-times out, or an invalid file descriptor is supplied as the argument to
-@option{-u}.
-Options, if supplied, have the following meanings:
-
-@table @code
-@item -a @var{aname}
-The words are assigned to sequential indices of the array variable
-@var{aname}, starting at 0.
-All elements are removed from @var{aname} before the assignment.
-Other @var{name} arguments are ignored.
-
-@item -d @var{delim}
-The first character of @var{delim} is used to terminate the input line,
-rather than newline.
-
-@item -e
-Readline (@pxref{Command Line Editing}) is used to obtain the line.
-
-@item -n @var{nchars}
-@code{read} returns after reading @var{nchars} characters rather than
-waiting for a complete line of input.
-
-@item -p @var{prompt}
-Display @var{prompt}, without a trailing newline, before attempting
-to read any input.
-The prompt is displayed only if input is coming from a terminal.
-
-@item -r
-If this option is given, 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.
-
-@item -s
-Silent mode.  If input is coming from a terminal, characters are
-not echoed.
-
-@item -t @var{timeout}
-Cause @code{read} to time out and return failure if a complete line of
-input is not read within @var{timeout} seconds.
-This option has no effect if @code{read} is not reading input from the
-terminal or a pipe.
-
-@item -u @var{fd}
-Read input from file descriptor @var{fd}.
-
-@end table
-
-@item shopt
-@btindex shopt
-@example
-shopt [-pqsu] [-o] [@var{optname} @dots{}]
-@end example
-Toggle the values of variables controlling optional shell behavior.
-With no options, or with the @option{-p} option, a list of all settable
-options is displayed, with an indication of whether or not each is set.
-The @option{-p} option causes output to be displayed in a form that
-may be reused as input.
-Other options have the following meanings:
-
-@table @code
-@item -s
-Enable (set) each @var{optname}.
-
-@item -u
-Disable (unset) each @var{optname}.
-
-@item -q
-Suppresses normal output; the return status
-indicates whether the @var{optname} is set or unset.
-If multiple @var{optname} arguments are given with @option{-q},
-the return status is zero if all @var{optnames} are enabled;
-non-zero otherwise.
-
-@item -o
-Restricts the values of
-@var{optname} to be those defined for the @option{-o} option to the
-@code{set} builtin (@pxref{The Set Builtin}).
-@end table
-
-If either @option{-s} or @option{-u}
-is used with no @var{optname} arguments, the display is limited to
-those options which are set or unset, respectively.
-
-Unless otherwise noted, the @code{shopt} options are disabled (off)
-by default.
-
-The return status when listing options is zero if all @var{optnames}
-are enabled, non-zero otherwise.  When setting or unsetting options,
-the return status is zero unless an @var{optname} is not a valid shell
-option.
-
-The list of @code{shopt} options is:
-@table @code
-@item cdable_vars
-If this is set, an argument to the @code{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.
-
-@item cdspell
-If set, minor errors in the spelling of a directory component in a
-@code{cd} command will be corrected.
-The errors checked for are transposed characters,
-a missing character, and a character too many.
-If a correction is found, the corrected path is printed,
-and the command proceeds.
-This option is only used by interactive shells.
-
-@item checkhash
-If this is 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.
-
-@item checkwinsize
-If set, Bash checks the window size after each command
-and, if necessary, updates the values of    
-@env{LINES} and @env{COLUMNS}.
-
-@item 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.
-
-@item dotglob
-If set, Bash includes filenames beginning with a `.' in
-the results of filename expansion.
-
-@item execfail
-If this is set, a non-interactive shell will not exit if
-it cannot execute the file specified as an argument to the @code{exec}
-builtin command.  An interactive shell does not exit if @code{exec}
-fails.
-
-@item expand_aliases
-If set, aliases are expanded as described below under Aliases,
-@ref{Aliases}.
-This option is enabled by default for interactive shells.
-
-@item extdebug
-If set, behavior intended for use by debuggers is enabled:
-
-@enumerate
-@item
-The @option{-F} option to the @code{declare} builtin (@pxref{Bash Builtins})
-displays the source file name and line number corresponding to each function
-name supplied as an argument.
-
-@item
-If the command run by the @code{DEBUG} trap returns a non-zero value, the
-next command is skipped and not executed.
-
-@item
-If the command run by the @code{DEBUG} trap returns a value of 2, and the
-shell is executing in a subroutine (a shell function or a shell script
-executed by the @code{.} or @code{source} builtins), a call to
-@code{return} is simulated.
-@end enumerate
-
-@item extglob
-If set, the extended pattern matching features described above
-(@pxref{Pattern Matching}) are enabled.
-
-@item extquote
-If set, @code{$'@var{string}'} and @code{$"@var{string}"} quoting is  
-performed within @code{$@{@var{parameter}@}} expansions                     
-enclosed in double quotes.  This option is enabled by default. 
-
-@item failglob
-If set, patterns which fail to match filenames during pathname expansion
-result in an expansion error.
-
-@item force_fignore
-If set, the suffixes specified by the @env{FIGNORE} shell variable
-cause words to be ignored when performing word completion even if
-the ignored words are the only possible completions.
-@xref{Bash Variables}, for a description of @env{FIGNORE}.
-This option is enabled by default.
-
-@item gnu_errfmt
-If set, shell error messages are written in the standard @sc{gnu} error
-message format.
-
-@item histappend
-If set, the history list is appended to the file named by the value
-of the @env{HISTFILE}
-variable when the shell exits, rather than overwriting the file.
-
-@item histreedit
-If set, and Readline
-is being used, a user is given the opportunity to re-edit a
-failed history substitution.
-
-@item 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.
-
-@item hostcomplete
-If set, and Readline is being used, Bash will attempt to perform
-hostname completion when a word containing a @samp{@@} is being
-completed (@pxref{Commands For Completion}).  This option is enabled
-by default.
-
-@item huponexit
-If set, Bash will send @code{SIGHUP} to all jobs when an interactive
-login shell exits (@pxref{Signals}).
-
-@item interactive_comments
-Allow a word beginning with @samp{#}
-to cause that word and all remaining characters on that
-line to be ignored in an interactive shell.
-This option is enabled by default.
-
-@item lithist
-If enabled, and the @code{cmdhist}
-option is enabled, multi-line commands are saved to the history with
-embedded newlines rather than using semicolon separators where possible.
-
-@item login_shell
-The shell sets this option if it is started as a login shell
-(@pxref{Invoking Bash}).
-The value may not be changed.
-
-@item mailwarn
-If set, and a file that Bash is checking for mail has been  
-accessed since the last time it was checked, the message
-@code{"The mail in @var{mailfile} has been read"} is displayed.
-
-@item no_empty_cmd_completion
-If set, and Readline is being used, Bash will not attempt to search
-the @env{PATH} for possible completions when completion is attempted
-on an empty line.
-
-@item nocaseglob
-If set, Bash matches filenames in a case-insensitive fashion when
-performing filename expansion.
-
-@item nullglob
-If set, Bash allows filename patterns which match no
-files to expand to a null string, rather than themselves.
-
-@item progcomp
-If set, the programmable completion facilities
-(@pxref{Programmable Completion}) are enabled.
-This option is enabled by default.
-
-@item promptvars
-If set, prompt strings undergo
-parameter expansion, command substitution, arithmetic
-expansion, and quote removal after being expanded
-as described below (@pxref{Printing a Prompt}).
-This option is enabled by default.
-
-@item restricted_shell
-The shell sets this option if it is started in restricted mode
-(@pxref{The Restricted Shell}).
-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.
-
-@item shift_verbose
-If this is set, the @code{shift}
-builtin prints an error message when the shift count exceeds the
-number of positional parameters.
-
-@item sourcepath
-If set, the @code{source} builtin uses the value of @env{PATH}
-to find the directory containing the file supplied as an argument.
-This option is enabled by default.
-
-@item xpg_echo
-If set, the @code{echo} builtin expands backslash-escape sequences
-by default.
-
-@end table
-
-@noindent
-The return status when listing options is zero if all @var{optnames}
-are enabled, non-zero otherwise.
-When setting or unsetting options, the return status is zero unless an
-@var{optname} is not a valid shell option.
-
-@item source
-@btindex source
-@example
-source @var{filename}
-@end example
-A synonym for @code{.} (@pxref{Bourne Shell Builtins}).
-
-@item type
-@btindex type
-@example
-type [-afptP] [@var{name} @dots{}]
-@end example
-For each @var{name}, indicate how it would be interpreted if used as a
-command name.
-
-If the @option{-t} option is used, @code{type} prints a single word
-which is one of @samp{alias}, @samp{function}, @samp{builtin},
-@samp{file} or @samp{keyword},
-if @var{name} is an alias, shell function, shell builtin,
-disk file, or shell reserved word, respectively.
-If the @var{name} is not found, then nothing is printed, and
-@code{type} returns a failure status.
-
-If the @option{-p} option is used, @code{type} either returns the name
-of the disk file that would be executed, or nothing if @option{-t}
-would not return @samp{file}.
-
-The @option{-P} option forces a path search for each @var{name}, even if
-@option{-t} would not return @samp{file}.
-
-If a command is hashed, @option{-p} and @option{-P} print the hashed value,
-not necessarily the file that appears first in @code{$PATH}.
-
-If the @option{-a} option is used, @code{type} returns all of the places
-that contain an executable named @var{file}.
-This includes aliases and functions, if and only if the @option{-p} option
-is not also used.
-
-If the @option{-f} option is used, @code{type} does not attempt to find
-shell functions, as with the @code{command} builtin.
-
-The return status is zero if any of the @var{names} are found, non-zero
-if none are found.
-
-@item typeset
-@btindex typeset
-@example
-typeset [-afFrxi] [-p] [@var{name}[=@var{value}] @dots{}]
-@end example
-The @code{typeset} command is supplied for compatibility with the Korn
-shell; however, it has been deprecated in favor of the @code{declare}
-builtin command.
-
-@item ulimit
-@btindex ulimit
-@example
-ulimit [-acdflmnpstuvSH] [@var{limit}]
-@end example
-@code{ulimit} provides control over the resources available to processes
-started by the shell, on systems that allow such control.  If an
-option is given, it is interpreted as follows:
-@table @code
-@item -S
-Change and report the soft limit associated with a resource.
-
-@item -H
-Change and report the hard limit associated with a resource.
-
-@item -a
-All current limits are reported.
-
-@item -c
-The maximum size of core files created.
-
-@item -d
-The maximum size of a process's data segment.
-
-@item -f
-The maximum size of files created by the shell.
-
-@item -l
-The maximum size that may be locked into memory.
-
-@item -m
-The maximum resident set size.
-
-@item -n
-The maximum number of open file descriptors.
-
-@item -p
-The pipe buffer size.
-
-@item -s
-The maximum stack size.
-
-@item -t
-The maximum amount of cpu time in seconds.
-
-@item -u
-The maximum number of processes available to a single user.
-
-@item -v
-The maximum amount of virtual memory available to the process.
-
-@end table
-
-If @var{limit} is given, it is the new value of the specified resource;
-the special @var{limit} values @code{hard}, @code{soft}, and
-@code{unlimited} stand for the current hard limit, the current soft limit,
-and no limit, respectively.
-Otherwise, the current value of the soft limit for the specified resource
-is printed, unless the @option{-H} option is supplied.
-When setting new limits, if neither @option{-H} nor @option{-S} is supplied,
-both the hard and soft limits are set.
-If no option is given, then @option{-f} is assumed.  Values are in 1024-byte
-increments, except for @option{-t}, which is in seconds, @option{-p},
-which is in units of 512-byte blocks, and @option{-n} and @option{-u}, which
-are unscaled values.
-
-The return status is zero unless an invalid option or argument is supplied,
-or an error occurs while setting a new limit.
-
-@item unalias
-@btindex unalias
-@example
-unalias [-a] [@var{name} @dots{} ]
-@end example
-
-Remove each @var{name} from the list of aliases.  If @option{-a} is
-supplied, all aliases are removed.
-Aliases are described in @ref{Aliases}.
-
-@end table
-
-@node The Set Builtin
-@section The Set Builtin
-
-This builtin is so complicated that it deserves its own section.
-
-@table @code
-@item set
-@btindex set
-@example
-set [--abefhkmnptuvxBCHP] [-o @var{option}] [@var{argument} @dots{}]
-@end example
-
-If no options or arguments are supplied, @code{set} displays the names
-and values of all shell variables and functions, sorted according to the
-current locale, in a format that may be reused as input.
-
-When options are supplied, they set or unset shell attributes.
-Options, if specified, have the following meanings:
-
-@table @code
-@item -a
-Mark variables and function which are modified or created for export
-to the environment of subsequent commands.
-
-@item -b
-Cause the status of terminated background jobs to be reported
-immediately, rather than before printing the next primary prompt.
-
-@item -e
-Exit immediately if a simple command (@pxref{Simple Commands}) exits
-with a non-zero status, unless the command that fails is part of the
-command list immediately following a @code{while} or @code{until}
-keyword, part of the test in an @code{if} statement,
-part of a @code{&&} or @code{||} list, or if the command's return
-status is being inverted using @code{!}.
-A trap on @code{ERR}, if set, is executed before the shell exits.
-
-@item -f
-Disable file name generation (globbing).
-
-@item -h
-Locate and remember (hash) commands as they are looked up for execution.
-This option is enabled by default.
-
-@item -k
-All arguments in the form of assignment statements are placed
-in the environment for a command, not just those that precede
-the command name.
-
-@item -m
-Job control is enabled (@pxref{Job Control}).
-
-@item -n
-Read commands but do not execute them; this may be used to check a
-script for syntax errors.
-This option is ignored by interactive shells.
-
-@item -o @var{option-name}
-
-Set the option corresponding to @var{option-name}:
-
-@table @code
-@item allexport
-Same as @code{-a}.
-
-@item braceexpand
-Same as @code{-B}.
-
-@item emacs
-Use an @code{emacs}-style line editing interface (@pxref{Command Line Editing}).
-
-@item errexit
-Same as @code{-e}.
-
-@item errtrace
-Same as @code{-E}.
-
-@item functrace
-Same as @code{-T}.
-
-@item hashall
-Same as @code{-h}.
-
-@item histexpand
-Same as @code{-H}.
-
-@item history
-Enable command history, as described in @ref{Bash History Facilities}.
-This option is on by default in interactive shells.
-
-@item ignoreeof
-An interactive shell will not exit upon reading EOF.
-
-@item keyword
-Same as @code{-k}.
-
-@item monitor
-Same as @code{-m}.
-
-@item noclobber
-Same as @code{-C}.
-
-@item noexec
-Same as @code{-n}.
-
-@item noglob
-Same as @code{-f}.
-
-@item nolog
-Currently ignored.
-
-@item notify
-Same as @code{-b}.
-
-@item nounset
-Same as @code{-u}.
-
-@item onecmd
-Same as @code{-t}.
-
-@item physical
-Same as @code{-P}.
-
-@item pipefail
-If set, the return value of a pipeline is the value of the last
-(rightmost) command to exit with a non-zero status, or zero if all
-commands in the pipeline exit successfully.
-This option is disabled by default.
-
-@item posix
-Change the behavior of Bash where the default operation differs
-from the @sc{posix} 1003.2 standard to match the standard
-(@pxref{Bash POSIX Mode}).
-This is intended to make Bash behave as a strict superset of that
-standard.
-
-@item privileged
-Same as @code{-p}.
-
-@item verbose
-Same as @code{-v}.
-
-@item vi
-Use a @code{vi}-style line editing interface.
-
-@item xtrace
-Same as @code{-x}.
-@end table
-
-@item -p
-Turn on privileged mode.
-In this mode, the @env{$BASH_ENV} and @env{$ENV} files are not
-processed, shell functions are not inherited from the environment,
-and the @env{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 @code{-p} option is not supplied, these actions
-are taken and the effective user id is set to the real user id.
-If the @code{-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.
-
-@item -t
-Exit after reading and executing one command.
-
-@item -u
-Treat unset variables as an error when performing parameter expansion.
-An error message will be written to the standard error, and a non-interactive
-shell will exit.
-
-@item -v
-Print shell input lines as they are read.
-
-@item -x
-Print a trace of simple commands, \fBfor\fP commands, \fBcase\fP
-commands, \fBselect\fP commands, and arithmetic \fBfor\fP commands
-and their arguments or associated word lists after they are
-expanded and before they are executed.  The value of the @env{PS4}
-variable is expanded and the resultant value is printed before
-the command and its expanded arguments.
-
-@item -B
-The shell will perform brace expansion (@pxref{Brace Expansion}).
-This option is on by default.
-
-@item -C
-Prevent output redirection using @samp{>}, @samp{>&}, and @samp{<>}
-from overwriting existing files.
-
-@item -E
-If set, any trap on @code{ERR} is inherited by shell functions, command
-substitutions, and commands executed in a subshell environment.
-The @code{ERR} trap is normally not inherited in such cases.
-
-@item -H
-Enable @samp{!} style history substitution (@pxref{History Interaction}).
-This option is on by default for interactive shells.
-
-@item -P
-If set, do not follow symbolic links when performing commands such as
-@code{cd} which change the current directory.  The physical directory
-is used instead.  By default, Bash follows
-the logical chain of directories when performing commands
-which change the current directory.
-
-For example, if @file{/usr/sys} is a symbolic link to @file{/usr/local/sys}
-then:
-@example
-$ cd /usr/sys; echo $PWD
-/usr/sys
-$ cd ..; pwd
-/usr
-@end example
-
-@noindent
-If @code{set -P} is on, then:
-@example
-$ cd /usr/sys; echo $PWD
-/usr/local/sys
-$ cd ..; pwd
-/usr/local
-@end example
-
-@item -T
-If set, any trap on @code{DEBUG} is inherited by shell functions, command
-substitutions, and commands executed in a subshell environment.
-The @code{DEBUG} trap is normally not inherited in such cases.
-
-@item --
-If no arguments follow this option, then the positional parameters are
-unset.  Otherwise, the positional parameters are set to the
-@var{arguments}, even if some of them begin with a @samp{-}.
-
-@item -
-Signal the end of options, cause all remaining @var{arguments}
-to be assigned to the positional parameters.  The @option{-x}
-and @option{-v}  options are turned off.
-If there are no arguments, the positional parameters remain unchanged.
-@end table
-
-Using @samp{+} rather than @samp{-} causes these options to be
-turned off.  The options can also be used upon invocation of the
-shell.  The current set of options may be found in @code{$-}.
-
-The remaining N @var{arguments} are positional parameters and are
-assigned, in order, to @code{$1}, @code{$2}, @dots{}  @code{$N}.
-The special parameter @code{#} is set to N.
-
-The return status is always zero unless an invalid option is supplied.
-@end table
-
-@node Special Builtins
-@section Special Builtins
-@cindex special builtin
-
-For historical reasons, the @sc{posix} 1003.2 standard has classified
-several builtin commands as @emph{special}.
-When Bash is executing in @sc{posix} mode, the special builtins
-differ from other builtin commands in three respects:
-
-@enumerate
-@item
-Special builtins are found before shell functions during command lookup.
-
-@item
-If a special builtin returns an error status, a non-interactive shell exits.
-
-@item
-Assignment statements preceding the command stay in effect in the shell
-environment after the command completes.
-@end enumerate
-
-When Bash is not executing in @sc{posix} mode, these builtins behave no
-differently than the rest of the Bash builtin commands.
-The Bash @sc{posix} mode is described in @ref{Bash POSIX Mode}. 
-
-These are the @sc{posix} special builtins:
-@example
-@w{break : . continue eval exec exit export readonly return set}
-@w{shift trap unset}
-@end example
-
-@node Shell Variables
-@chapter Shell Variables
-
-@menu
-* Bourne Shell Variables::	Variables which Bash uses in the same way
-				as the Bourne Shell.
-* Bash Variables::		List of variables that exist in Bash.
-@end menu
-
-This chapter describes the shell variables that Bash uses.
-Bash automatically assigns default values to a number of variables.
-
-@node Bourne Shell Variables
-@section Bourne Shell Variables
-
-Bash uses certain shell variables in the same way as the Bourne shell.
-In some cases, Bash assigns a default value to the variable.
-
-@vtable @code
-
-@item CDPATH
-A colon-separated list of directories used as a search path for
-the @code{cd} builtin command.
-
-@item HOME
-The current user's home directory; the default for the @code{cd} builtin
-command.
-The value of this variable is also used by tilde expansion
-(@pxref{Tilde Expansion}).
-
-@item IFS
-A list of characters that separate fields; used when the shell splits
-words as part of expansion.
-
-@item MAIL
-If this parameter is set to a filename and the @env{MAILPATH} variable
-is not set, Bash informs the user of the arrival of mail in
-the specified file.
-
-@item MAILPATH
-A colon-separated list of filenames which the shell periodically checks
-for new mail.
-Each list entry can specify the message that is printed when new mail
-arrives in the mail file by separating the file name from the message with
-a @samp{?}.
-When used in the text of the message, @code{$_} expands to the name of
-the current mail file.
-
-@item OPTARG
-The value of the last option argument processed by the @code{getopts} builtin.
-
-@item OPTIND
-The index of the last option argument processed by the @code{getopts} builtin.
-
-@item PATH
-A colon-separated list of directories in which the shell looks for
-commands.
-A zero-length (null) directory name in the value of @code{PATH} indicates the
-current directory.
-A null directory name may appear as two adjacent colons, or as an initial
-or trailing colon.
-
-
-@item PS1
-The primary prompt string.  The default value is @samp{\s-\v\$ }.
-@xref{Printing a Prompt}, for the complete list of escape
-sequences that are expanded before @env{PS1} is displayed.
-
-@item PS2
-The secondary prompt string.  The default value is @samp{> }.
-
-@end vtable
-
-@node Bash Variables
-@section Bash Variables
-
-These variables are set or used by Bash, but other shells
-do not normally treat them specially.
-
-A few variables used by Bash are described in different chapters:
-variables for controlling the job control facilities
-(@pxref{Job Control Variables}).
-
-@vtable @code
-
-@item BASH
-The full pathname used to execute the current instance of Bash.
-
-@item BASH_ARGC
-An array variable whose values are the number of parameters in each
-frame of the current bash execution call stack.  The number of
-parameters to the current subroutine (shell function or script executed
-with @code{.} or @code{source}) is at the top of the stack.  When a
-subroutine is executed, the number of parameters passed is pushed onto
-@code{BASH_ARGC}.
-
-@item BASH_ARGV
-An array variable containing all of the parameters in the current bash
-execution call stack.  The final parameter of the last subroutine call
-is at the top of the stack; the first parameter of the initial call is
-at the bottom.  When a subroutine is executed, the parameters supplied
-are pushed onto @code{BASH_ARGV}.
-
-@item BASH_COMMAND
-The command currently being executed or about to be executed, unless the
-shell is executing a command as the result of a trap,
-in which case it is the command executing at the time of the trap.
-
-@item BASH_ENV
-If this variable is set when Bash is invoked to execute a shell
-script, its value is expanded and used as the name of a startup file
-to read before executing the script.  @xref{Bash Startup Files}.
-
-@item BASH_EXECUTION_STRING
-The command argument to the @option{-c} invocation option.
-
-@item BASH_LINENO
-An array variable whose members are the line numbers in source files
-corresponding to each member of @var{FUNCNAME}.
-@code{$@{BASH_LINENO[$i]@}} is the line number in the source file where
-@code{$@{FUNCNAME[$i + 1]@}} was called.
-The corresponding source file name is @code{$@{BASH_SOURCE[$i + 1]@}}.
-Use @code{LINENO} to obtain the current line number.
-
-@item BASH_REMATCH
-An array variable whose members are assigned by the @samp{=~} binary
-operator to the @code{[[} conditional command
-(@pxref{Conditional Constructs}).
-The element with index 0 is the portion of the string
-matching the entire regular expression.
-The element with index @var{n} is the portion of the
-string matching the @var{n}th parenthesized subexpression.
-This variable is read-only.
-
-@item BASH_SOURCE
-An array variable whose members are the source filenames corresponding
-to the elements in the @code{FUNCNAME} array variable.
-
-@item BASH_SUBSHELL
-Incremented by one each time a subshell or subshell environment is spawned.
-The initial value is 0.
-
-@item BASH_VERSINFO
-A readonly array variable (@pxref{Arrays})
-whose members hold version information for this instance of Bash.
-The values assigned to the array members are as follows:
-
-@table @code
-
-@item BASH_VERSINFO[0]
-The major version number (the @var{release}).
-
-@item BASH_VERSINFO[1]
-The minor version number (the @var{version}).
-
-@item BASH_VERSINFO[2]
-The patch level.
-
-@item BASH_VERSINFO[3]
-The build version.
-
-@item BASH_VERSINFO[4]
-The release status (e.g., @var{beta1}).
-
-@item BASH_VERSINFO[5]
-The value of @env{MACHTYPE}.
-
-@end table
-
-@item BASH_VERSION
-The version number of the current instance of Bash.
-
-@item COLUMNS
-Used by the @code{select} builtin command to determine the terminal width
-when printing selection lists.  Automatically set upon receipt of a
-@code{SIGWINCH}.
-
-@item COMP_CWORD
-An index into @env{$@{COMP_WORDS@}} of the word containing the current
-cursor position.
-This variable is available only in shell functions invoked by the
-programmable completion facilities (@pxref{Programmable Completion}).
-
-@item COMP_LINE
-The current command line.
-This variable is available only in shell functions and external
-commands invoked by the
-programmable completion facilities (@pxref{Programmable Completion}).
-
-@item 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 @code{$@{#COMP_LINE@}}.
-This variable is available only in shell functions and external
-commands invoked by the
-programmable completion facilities (@pxref{Programmable Completion}).
-
-@item COMP_WORDBREAKS
-The set of characters that the Readline library treats as word
-separators when performing word completion.
-If @code{COMP_WORDBREAKS} is unset, it loses its special properties,
-even if it is subsequently reset.
-
-@item COMP_WORDS
-An array variable consisting of the individual
-words in the current command line.
-This variable is available only in shell functions invoked by the
-programmable completion facilities (@pxref{Programmable Completion}).
-
-@item COMPREPLY
-An array variable from which Bash reads the possible completions
-generated by a shell function invoked by the programmable completion
-facility (@pxref{Programmable Completion}).
-
-@item DIRSTACK
-An array variable containing the current contents of the directory stack.
-Directories appear in the stack in the order they are displayed by the
-@code{dirs} builtin.
-Assigning to members of this array variable may be used to modify
-directories already in the stack, but the @code{pushd} and @code{popd}
-builtins must be used to add and remove directories.
-Assignment to this variable will not change the current directory.
-If @env{DIRSTACK} is unset, it loses its special properties, even if
-it is subsequently reset.
-
-@item EMACS
-If Bash finds this variable in the environment when the shell
-starts with value @samp{t}, it assumes that the shell is running in an
-emacs shell buffer and disables line editing.
-
-@item EUID
-The numeric effective user id of the current user.  This variable
-is readonly.
-
-@item FCEDIT
-The editor used as a default by the @option{-e} option to the @code{fc}
-builtin command.
-
-@item FIGNORE
-A colon-separated list of suffixes to ignore when performing
-filename completion.
-A file name whose suffix matches one of the entries in 
-@env{FIGNORE}
-is excluded from the list of matched file names.  A sample
-value is @samp{.o:~}
-
-@item FUNCNAME
-An array variable containing the names of all shell functions
-currently in the execution call stack.
-The element with index 0 is the name of any currently-executing
-shell function.
-The bottom-most element is "main".
-This variable exists only when a shell function is executing.
-Assignments to @env{FUNCNAME} have no effect and return an error status.
-If @env{FUNCNAME} is unset, it loses its special properties, even if
-it is subsequently reset.
-
-@item GLOBIGNORE
-A colon-separated list of patterns defining the set of filenames to
-be ignored by filename expansion.
-If a filename matched by a filename expansion pattern also matches one
-of the patterns in @env{GLOBIGNORE}, it is removed from the list
-of matches.
-
-@item GROUPS
-An array variable containing the list of groups of which the current    
-user is a member.
-Assignments to @env{GROUPS} have no effect and return an error status.
-If @env{GROUPS} is unset, it loses its special properties, even if it is
-subsequently reset.
-
-@item histchars
-Up to three characters which control history expansion, quick
-substitution, and tokenization (@pxref{History Interaction}).
-The first character is the
-@var{history expansion} character, that is, the character which signifies the
-start of a history expansion, normally @samp{!}.  The second character is the
-character which signifies `quick substitution' when seen as the first
-character on a line, normally @samp{^}.  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, usually @samp{#}.  The history
-comment character causes history substitution to be skipped for the
-remaining words on the line.  It does not necessarily cause the shell
-parser to treat the rest of the line as a comment.
-
-@item HISTCMD
-The history number, or index in the history list, of the current
-command.  If @env{HISTCMD} is unset, it loses its special properties,
-even if it is subsequently reset.
-
-@item HISTCONTROL
-A colon-separated list of values controlling how commands are saved on
-the history list.
-If the list of values includes @samp{ignorespace}, lines which begin
-with a space character are not saved in the history list.
-A value of @samp{ignoredups} causes lines which match the previous
-history entry to not be saved.
-A value of @samp{ignoreboth} is shorthand for
-@samp{ignorespace} and @samp{ignoredups}.
-A value of @samp{erasedups} causes all previous lines matching the
-current line to be removed from the history list before that line
-is saved.
-Any value not in the above list is ignored.
-If @env{HISTCONTROL} is unset, or does not include a valid value, 
-all lines read by the shell parser are saved on the history list, 
-subject to the value of @env{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
-@env{HISTCONTROL}.
-
-@item HISTFILE
-The name of the file to which the command history is saved.  The
-default value is @file{~/.bash_history}.
-
-@item 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 history file is also truncated to this size after
-writing it when an interactive shell exits.
-The default value is 500.
-
-@item 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 @samp{*} is appended).  Each pattern is tested
-against the line after the checks specified by @env{HISTCONTROL}
-are applied.  In addition to the normal shell pattern matching
-characters, @samp{&} matches the previous history line.  @samp{&}
-may be escaped using a backslash; the backslash is removed
-before attempting a match. 
-The second and subsequent lines of a multi-line compound command are
-not tested, and are added to the history regardless of the value of
-@env{HISTIGNORE}.
-
-@env{HISTIGNORE} subsumes the function of @env{HISTCONTROL}.  A
-pattern of @samp{&} is identical to @code{ignoredups}, and a
-pattern of @samp{[ ]*} is identical to @code{ignorespace}. 
-Combining these two patterns, separating them with a colon,
-provides the functionality of @code{ignoreboth}. 
-
-@item HISTSIZE
-The maximum number of commands to remember on the history list.
-The default value is 500.
-
-@item HISTTIMEFORMAT
-If this variable is set and not null, its value is used as a format string
-for @var{strftime} to print the time stamp associated with each history
-entry displayed by the @code{history} builtin.
-If this variable is set, time stamps are written to the history file so
-they may be preserved across shell sessions.
-
-@item HOSTFILE
-Contains the name of a file in the same format as @file{/etc/hosts} that
-should be read when the shell needs to complete a hostname.
-The list of possible hostname completions may be changed while the shell
-is running;
-the next time hostname completion is attempted after the
-value is changed, Bash adds the contents of the new file to the
-existing list.
-If @env{HOSTFILE} is set, but has no value, Bash attempts to read 
-@file{/etc/hosts} to obtain the list of possible hostname completions.
-When @env{HOSTFILE} is unset, the hostname list is cleared.
-
-@item HOSTNAME
-The name of the current host.
-
-@item HOSTTYPE
-A string describing the machine Bash is running on.
-
-@item IGNOREEOF
-Controls the action of the shell on receipt of an @code{EOF} character
-as the sole input.  If set, the value denotes the number
-of consecutive @code{EOF} characters that can be read as the
-first character on an input line
-before the shell will exit.  If the variable exists but does not
-have a numeric value (or has no value) then the default is 10.
-If the variable does not exist, then @code{EOF} signifies the end of 
-input to the shell.  This is only in effect for interactive shells.
-
-@item INPUTRC
-The name of the Readline initialization file, overriding the default
-of @file{~/.inputrc}.
-
-@item LANG  
-Used to determine the locale category for any category not specifically
-selected with a variable starting with @code{LC_}.
-
-@item LC_ALL
-This variable overrides the value of @env{LANG} and any other
-@code{LC_} variable specifying a locale category.
-
-@item LC_COLLATE
-This variable determines the collation order used when sorting the
-results of filename expansion, and
-determines the behavior of range expressions, equivalence classes,
-and collating sequences within filename expansion and pattern matching
-(@pxref{Filename Expansion}).
-
-@item LC_CTYPE
-This variable determines the interpretation of characters and the
-behavior of character classes within filename expansion and pattern
-matching (@pxref{Filename Expansion}).
-
-@item LC_MESSAGES
-This variable determines the locale used to translate double-quoted
-strings preceded by a @samp{$} (@pxref{Locale Translation}).
-
-@item LC_NUMERIC
-This variable determines the locale category used for number formatting.
-
-@item LINENO
-The line number in the script or shell function currently executing.
-
-@item LINES
-Used by the @code{select} builtin command to determine the column length
-for printing selection lists.  Automatically set upon receipt of a
-@code{SIGWINCH}.
-
-@item MACHTYPE
-A string that fully describes the system type on which Bash
-is executing, in the standard @sc{gnu} @var{cpu-company-system} format.
-
-@item MAILCHECK
-How often (in seconds) that the shell should check for mail in the
-files specified in the @env{MAILPATH} or @env{MAIL} variables.
-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.
-
-@item OLDPWD
-The previous working directory as set by the @code{cd} builtin.
-
-@item OPTERR
-If set to the value 1, Bash displays error messages
-generated by the @code{getopts} builtin command.
-
-@item OSTYPE
-A string describing the operating system Bash is running on.
-
-@item PIPESTATUS
-An array variable (@pxref{Arrays})
-containing a list of exit status values from the processes
-in the most-recently-executed foreground pipeline (which may
-contain only a single command).
-
-@item POSIXLY_CORRECT
-If this variable is in the environment when @code{bash} starts, the shell
-enters @sc{posix} mode (@pxref{Bash POSIX Mode}) before reading the
-startup files, as if the @option{--posix} invocation option had been supplied.
-If it is set while the shell is running, @code{bash} enables @sc{posix} mode,
-as if the command
-@example
-@code{set -o posix}
-@end example
-@noindent
-had been executed.  
-
-@item PPID
-The process @sc{id} of the shell's parent process.  This variable
-is readonly.
-
-@item PROMPT_COMMAND
-If set, the value is interpreted as a command to execute
-before the printing of each primary prompt (@env{$PS1}).
-
-@item PS3
-The value of this variable is used as the prompt for the
-@code{select} command.  If this variable is not set, the
-@code{select} command prompts with @samp{#? }
-
-@item PS4
-The value is the prompt printed before the command line is echoed
-when the @option{-x} option is set (@pxref{The Set Builtin}).
-The first character of @env{PS4} is replicated multiple times, as
-necessary, to indicate multiple levels of indirection.
-The default is @samp{+ }.
-
-@item PWD
-The current working directory as set by the @code{cd} builtin.
-
-@item RANDOM
-Each time this parameter is referenced, a random integer
-between 0 and 32767 is generated.  Assigning a value to this
-variable seeds the random number generator.
-
-@item REPLY
-The default variable for the @code{read} builtin.
-
-@item SECONDS
-This variable expands to the number of seconds since the
-shell was started.  Assignment to this variable resets
-the count to the value assigned, and the expanded value
-becomes the value assigned plus the number of seconds
-since the assignment.
-
-@item SHELL
-The full pathname to the shell is kept in this environment variable.
-If it is not set when the shell starts,
-Bash assigns to it the full pathname of the current user's login shell.
-
-@item SHELLOPTS
-A colon-separated list of enabled shell options.  Each word in
-the list is a valid argument for the @option{-o} option to the
-@code{set} builtin command (@pxref{The Set Builtin}).
-The options appearing in @env{SHELLOPTS} are those reported
-as @samp{on} by @samp{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 readonly.
-
-@item SHLVL
-Incremented by one each time a new instance of Bash is started.  This is
-intended to be a count of how deeply your Bash shells are nested.
-
-@item TIMEFORMAT
-The value of this parameter is used as a format string specifying
-how the timing information for pipelines prefixed with the @code{time}
-reserved word should be displayed.
-The @samp{%} 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. 
-
-@table @code
-
-@item %%
-A literal @samp{%}.
-
-@item %[@var{p}][l]R
-The elapsed time in seconds. 
-
-@item %[@var{p}][l]U
-The number of CPU seconds spent in user mode. 
-
-@item %[@var{p}][l]S
-The number of CPU seconds spent in system mode. 
-
-@item %P
-The CPU percentage, computed as (%U + %S) / %R. 
-@end table
-
-The optional @var{p} is a digit specifying the precision, the number of
-fractional digits after a decimal point.
-A value of 0 causes no decimal point or fraction to be output.
-At most three places after the decimal point may be specified; values
-of @var{p} greater than 3 are changed to 3.
-If @var{p} is not specified, the value 3 is used. 
-
-The optional @code{l} specifies a longer format, including minutes, of
-the form @var{MM}m@var{SS}.@var{FF}s.
-The value of @var{p} determines whether or not the fraction is included. 
-
-If this variable is not set, Bash acts as if it had the value
-@example
-@code{$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'}
-@end example
-If the value is null, no timing information is displayed.
-A trailing newline is added when the format string is displayed.
-
-@item TMOUT
-If set to a value greater than zero, @code{TMOUT} is treated as the
-default timeout for the @code{read} builtin (@pxref{Bash Builtins}).
-The @code{select} command (@pxref{Conditional Constructs}) terminates
-if input does not arrive after @code{TMOUT} seconds when input is coming
-from a terminal.
-
-In an interative shell, the value is interpreted as
-the number of seconds to wait for input after issuing the primary
-prompt when the shell is interactive.
-Bash terminates after that number of seconds if input does
-not arrive.
-
-@item UID
-The numeric real user id of the current user.  This variable is readonly.
-
-@end vtable
-
-@node Bash Features
-@chapter Bash Features
-
-This section describes features unique to Bash.
-
-@menu
-* Invoking Bash::		Command line options that you can give
-				to Bash.
-* Bash Startup Files::		When and how Bash executes scripts.
-* Interactive Shells::		What an interactive shell is.
-* Bash Conditional Expressions::	Primitives used in composing expressions for
-				the @code{test} builtin.
-* Shell Arithmetic::		Arithmetic on shell variables.
-* Aliases::			Substituting one command for another.
-* Arrays::			Array Variables.
-* The Directory Stack::		History of visited directories.
-* Printing a Prompt::		Controlling the PS1 string.
-* The Restricted Shell::	A more controlled mode of shell execution.
-* Bash POSIX Mode::		Making Bash behave more closely to what
-				the POSIX standard specifies.
-@end menu
-
-@node Invoking Bash
-@section Invoking Bash
-
-@example
-bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] [@var{argument} @dots{}]
-bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] -c @var{string} [@var{argument} @dots{}]
-bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o @var{option}] [-O @var{shopt_option}] [@var{argument} @dots{}]
-@end example
-
-In addition to the single-character shell command-line options
-(@pxref{The Set Builtin}), there are several multi-character
-options that you can use.  These options must appear on the command
-line before the single-character options to be recognized. 
-
-@table @code
-@item --debugger
-Arrange for the debugger profile to be executed before the shell
-starts.  Turns on extended debugging mode (see @ref{Bash Builtins}
-for a description of the @code{extdebug} option to the @code{shopt}
-builtin) and shell function tracing
-(see @ref{The Set Builtin} for a description of the @code{-o functrace}
-option).
-
-@item --dump-po-strings
-A list of all double-quoted strings preceded by @samp{$}
-is printed on the standard ouput
-in the @sc{gnu} @code{gettext} PO (portable object) file format.
-Equivalent to @option{-D} except for the output format.
-
-@item --dump-strings
-Equivalent to @option{-D}.
-
-@item --help
-Display a usage message on standard output and exit sucessfully.
-
-@item --init-file @var{filename}
-@itemx --rcfile @var{filename}
-Execute commands from @var{filename} (instead of @file{~/.bashrc})
-in an interactive shell.
-
-@item --login
-Equivalent to @option{-l}.
-
-@item --noediting
-Do not use the @sc{gnu} Readline library (@pxref{Command Line Editing})
-to read  command lines when the shell is interactive.
-
-@item --noprofile
-Don't load the system-wide startup file @file{/etc/profile}
-or any of the personal initialization files
-@file{~/.bash_profile}, @file{~/.bash_login}, or @file{~/.profile}
-when Bash is invoked as a login shell.
-
-@item --norc
-Don't read the @file{~/.bashrc} initialization file in an
-interactive shell.  This is on by default if the shell is
-invoked as @code{sh}.
-
-@item --posix
-Change the behavior of Bash where the default operation differs
-from the @sc{posix} 1003.2 standard to match the standard.  This
-is intended to make Bash behave as a strict superset of that
-standard.  @xref{Bash POSIX Mode}, for a description of the Bash
-@sc{posix} mode.
-
-@item --restricted
-Make the shell a restricted shell (@pxref{The Restricted Shell}).
-
-@item --verbose
-Equivalent to @option{-v}.  Print shell input lines as they're read.
-
-@item --version
-Show version information for this instance of
-Bash on the standard output and exit successfully.
-
-@end table
-
-There are several single-character options that may be supplied at
-invocation which are not available with the @code{set} builtin.
-
-@table @code
-@item -c @var{string}
-Read and execute commands from @var{string} after processing the
-options, then exit.  Any remaining arguments are assigned to the
-positional parameters, starting with @code{$0}.
-
-@item -i
-Force the shell to run interactively.  Interactive shells are
-described in @ref{Interactive Shells}.
-
-@item -l
-Make this shell act as if it had been directly invoked by login.
-When the shell is interactive, this is equivalent to starting a
-login shell with @samp{exec -l bash}.
-When the shell is not interactive, the login shell startup files will
-be executed.
-@samp{exec bash -l} or @samp{exec bash --login}
-will replace the current shell with a Bash login shell.
-@xref{Bash Startup Files}, for a description of the special behavior
-of a login shell.
-
-@item -r
-Make the shell a restricted shell (@pxref{The Restricted Shell}).
-
-@item -s
-If this option is present, or if no arguments remain after option
-processing, then commands are read from the standard input.
-This option allows the positional parameters to be set
-when invoking an interactive shell.
-
-@item -D
-A list of all double-quoted strings preceded by @samp{$}
-is printed on the standard ouput.
-These are the strings that
-are subject to language translation when the current locale
-is not @code{C} or @code{POSIX} (@pxref{Locale Translation}).
-This implies the @option{-n} option; no commands will be executed.
-
-@item [-+]O [@var{shopt_option}]
-@var{shopt_option} is one of the shell options accepted by the
-@code{shopt} builtin (@pxref{Shell Builtin Commands}).
-If @var{shopt_option} is present, @option{-O} sets the value of that option;
-@option{+O} unsets it.  
-If @var{shopt_option} is not supplied, the names and values of the shell
-options accepted by @code{shopt} are printed on the standard output.
-If the invocation option is @option{+O}, the output is displayed in a format
-that may be reused as input.
-
-@item --
-A @code{--} signals the end of options and disables further option
-processing.
-Any arguments after the @code{--} are treated as filenames and arguments.
-
-@end table
-
-@cindex login shell
-A @emph{login} shell is one whose first character of argument zero is
-@samp{-}, or one invoked with the @option{--login} option.
-
-@cindex interactive shell
-An @emph{interactive} shell is one started without non-option arguments,
-unless @option{-s} is specified,
-without specifying the @option{-c} option, and whose input and output are both
-connected to terminals (as determined by @code{isatty(3)}), or one
-started with the @option{-i} option.  @xref{Interactive Shells}, for more
-information.
-
-If arguments remain after option processing, and neither the
-@option{-c} nor the @option{-s}
-option has been supplied, the first argument is assumed to
-be the name of a file containing shell commands (@pxref{Shell Scripts}).
-When Bash is invoked in this fashion, @code{$0}
-is set to the name of the file, and the positional parameters
-are set to the remaining arguments.
-Bash reads and executes commands from this file, then exits.   
-Bash's exit status is the exit status of the last command executed
-in the script.  If no commands are executed, the exit status is 0.
-
-@node Bash Startup Files
-@section Bash Startup Files
-@cindex startup files
-
-This section describs 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 above under
-Tilde Expansion (@pxref{Tilde Expansion}).
-
-Interactive shells are described in @ref{Interactive Shells}.
-
-@subsubheading Invoked as an interactive login shell, or with @option{--login}
-
-When Bash is invoked as an interactive login shell, or as a
-non-interactive shell with the @option{--login} option, it first reads and
-executes commands from the file @file{/etc/profile}, if that file exists.
-After reading that file, it looks for @file{~/.bash_profile},
-@file{~/.bash_login}, and @file{~/.profile}, in that order, and reads
-and executes commands from the first one that exists and is readable.
-The @option{--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 @file{~/.bash_logout}, if it exists.
-
-@subsubheading Invoked as an interactive non-login shell
-
-When an interactive shell that is not a login shell is started, Bash
-reads and executes commands from @file{~/.bashrc}, if that file exists.
-This may be inhibited by using the @option{--norc} option.
-The @option{--rcfile @var{file}} option will force Bash to read and
-execute commands from @var{file} instead of @file{~/.bashrc}.
-
-So, typically, your @file{~/.bash_profile} contains the line
-@example
-@code{if [ -f ~/.bashrc ]; then . ~/.bashrc; fi}
-@end example
-@noindent
-after (or before) any login-specific initializations.
-
-@subsubheading Invoked non-interactively
-
-When Bash is started non-interactively, to run a shell script,
-for example, it looks for the variable @env{BASH_ENV} in the environment,
-expands its value if it appears there, and uses the expanded value as
-the name of a file to read and execute.  Bash behaves as if the
-following command were executed:
-@example
-@code{if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi}
-@end example
-@noindent
-but the value of the @env{PATH} variable is not used to search for the
-file name.
-
-As noted above, if a non-interactive shell is invoked with the
-@option{--login} option, Bash attempts to read and execute commands from the
-login shell startup files. 
-
-@subsubheading Invoked with name @code{sh}
-
-If Bash is invoked with the name @code{sh}, it tries to mimic the
-startup behavior of historical versions of @code{sh} as closely as
-possible, while conforming to the @sc{posix} standard as well.
-
-When invoked as an interactive login shell, or as a non-interactive
-shell with the @option{--login} option, it first attempts to read
-and execute commands from @file{/etc/profile} and @file{~/.profile}, in
-that order.
-The @option{--noprofile} option may be used to inhibit this behavior.
-When invoked as an interactive shell with the name @code{sh}, Bash
-looks for the variable @env{ENV}, expands its value if it is defined,
-and uses the expanded value as the name of a file to read and execute.
-Since a shell invoked as @code{sh} does not attempt to read and execute
-commands from any other startup files, the @option{--rcfile} option has
-no effect.
-A non-interactive shell invoked with the name @code{sh} does not attempt
-to read any other startup files.
-
-When invoked as @code{sh}, Bash enters @sc{posix} mode after
-the startup files are read.
-
-@subsubheading Invoked in @sc{posix} mode
-
-When Bash is started in @sc{posix} mode, as with the
-@option{--posix} command line option, it follows the @sc{posix} standard
-for startup files.
-In this mode, interactive shells expand the @env{ENV} variable
-and commands are read and executed from the file whose name is the
-expanded value.
-No other startup files are read.
-
-@subsubheading Invoked by remote shell daemon
-
-Bash attempts to determine when it is being run by the remote shell
-daemon, usually @code{rshd}.  If Bash determines it is being run by
-rshd, it reads and executes commands from @file{~/.bashrc}, if that
-file exists and is readable.
-It will not do this if invoked as @code{sh}.
-The @option{--norc} option may be used to inhibit this behavior, and the
-@option{--rcfile} option may be used to force another file to be read, but
-@code{rshd} does not generally invoke the shell with those options or
-allow them to be specified.
-
-@subsubheading Invoked with unequal effective and real @sc{uid/gid}s
-
-If Bash is started with the effective user (group) id not equal to the
-real user (group) id, and the @code{-p} option is not supplied, no startup
-files are read, shell functions are not inherited from the environment,
-the @env{SHELLOPTS} variable, if it appears in the environment, is ignored,
-and the effective user id is set to the real user id.
-If the @code{-p} option is supplied at invocation, the startup behavior is
-the same, but the effective user id is not reset.
-
-@node Interactive Shells
-@section Interactive Shells
-@cindex interactive shell
-@cindex shell, interactive
-
-@menu
-* What is an Interactive Shell?::	What determines whether a shell is Interactive.
-* Is this Shell Interactive?::	How to tell if a shell is interactive.
-* Interactive Shell Behavior::	What changes in a interactive shell?
-@end menu
-
-@node What is an Interactive Shell?
-@subsection What is an Interactive Shell?
-
-An interactive shell
-is one started without non-option arguments, unless @option{-s} is
-specified, without specifiying the @option{-c} option, and
-whose input and output are both
-connected to terminals (as determined by @code{isatty(3)}),
-or one started with the @option{-i} option.
-
-An interactive shell generally reads from and writes to a user's
-terminal.
-
-The @option{-s} invocation option may be used to set the positional parameters
-when an interactive shell is started.
-
-@node Is this Shell Interactive?
-@subsection Is this Shell Interactive?
-
-To determine within a startup script whether or not Bash is
-running interactively,
-test the value of the @samp{-} special parameter.
-It contains @code{i} when the shell is interactive.  For example:
-
-@example
-case "$-" in
-*i*)	echo This shell is interactive ;;
-*)	echo This shell is not interactive ;;
-esac
-@end example
-
-Alternatively, startup scripts may examine the variable
-@env{PS1}; it is unset in non-interactive shells, and set in
-interactive shells.  Thus:
-
-@example
-if [ -z "$PS1" ]; then
-        echo This shell is not interactive
-else
-        echo This shell is interactive
-fi
-@end example
-
-@node Interactive Shell Behavior
-@subsection Interactive Shell Behavior
-
-When the shell is running interactively, it changes its behavior in
-several ways.
-
-@enumerate
-@item
-Startup files are read and executed as described in @ref{Bash Startup Files}.
-
-@item
-Job Control (@pxref{Job Control}) is enabled by default.  When job
-control is in effect, Bash ignores the keyboard-generated job control
-signals @code{SIGTTIN}, @code{SIGTTOU}, and @code{SIGTSTP}.
-
-@item
-Bash expands and displays @env{PS1} before reading the first line
-of a command, and expands and displays @env{PS2} before reading the
-second and subsequent lines of a multi-line command.
-
-@item
-Bash executes the value of the @env{PROMPT_COMMAND} variable as a command
-before printing the primary prompt, @env{$PS1}
-(@pxref{Bash Variables}).
-
-@item
-Readline (@pxref{Command Line Editing}) is used to read commands from
-the user's terminal.
-
-@item
-Bash inspects the value of the @code{ignoreeof} option to @code{set -o}
-instead of exiting immediately when it receives an @code{EOF} on its
-standard input when reading a command (@pxref{The Set Builtin}).
-
-@item
-Command history (@pxref{Bash History Facilities})
-and history expansion (@pxref{History Interaction})
-are enabled by default.
-Bash will save the command history to the file named by @env{$HISTFILE}
-when an interactive shell exits.
-
-@item
-Alias expansion (@pxref{Aliases}) is performed by default.
-
-@item
-In the absence of any traps, Bash ignores @code{SIGTERM}
-(@pxref{Signals}).
-
-@item
-In the absence of any traps, @code{SIGINT} is caught and handled
-((@pxref{Signals}).
-@code{SIGINT} will interrupt some shell builtins.
-
-@item
-An interactive login shell sends a @code{SIGHUP} to all jobs on exit
-if the @code{hupoxexit} shell option has been enabled (@pxref{Signals}).
-
-@item
-The @option{-n} invocation option is ignored, and @samp{set -n} has
-no effect (@pxref{The Set Builtin}).
-
-@item
-Bash will check for mail periodically, depending on the values of the
-@env{MAIL}, @env{MAILPATH}, and @env{MAILCHECK} shell variables
-(@pxref{Bash Variables}).
-
-@item
-Expansion errors due to references to unbound shell variables after
-@samp{set -u} has been enabled will not cause the shell to exit
-(@pxref{The Set Builtin}).
-
-@item
-The shell will not exit on expansion errors caused by @var{var} being unset
-or null in @code{$@{@var{var}:?@var{word}@}} expansions
-(@pxref{Shell Parameter Expansion}).
-
-@item
-Redirection errors encountered by shell builtins will not cause the
-shell to exit.
-
-@item
-When running in @sc{posix} mode, a special builtin returning an error
-status will not cause the shell to exit (@pxref{Bash POSIX Mode}).
-@item
-A failed @code{exec} will not cause the shell to exit
-(@pxref{Bourne Shell Builtins}).
-
-@item
-Parser syntax errors will not cause the shell to exit.
-
-@item
-Simple spelling correction for directory arguments to the @code{cd}
-builtin is enabled by default (see the description of the @code{cdspell}
-option to the @code{shopt} builtin in @ref{Bash Builtins}).
-
-@item
-The shell will check the value of the @env{TMOUT} variable and exit
-if a command is not read within the specified number of seconds after
-printing @env{$PS1} (@pxref{Bash Variables}).
-
-@end enumerate
-
-@node Bash Conditional Expressions
-@section Bash Conditional Expressions
-@cindex expressions, conditional
-
-Conditional expressions are used by the @code{[[} compound command
-and the @code{test} and @code{[} builtin commands.
-
-Expressions may be unary or binary.
-Unary expressions are often used to examine the status of a file.
-There are string operators and numeric comparison operators as well.
-If the @var{file} argument to one of the primaries is of the form
-@file{/dev/fd/@var{N}}, then file descriptor @var{N} is checked.
-If the @var{file} argument to one of the primaries is one of
-@file{/dev/stdin}, @file{/dev/stdout}, or @file{/dev/stderr}, file
-descriptor 0, 1, or 2, respectively, is checked.
-
-@table @code
-@item -a @var{file}
-True if @var{file} exists.
-
-@item -b @var{file}
-True if @var{file} exists and is a block special file.
-
-@item -c @var{file}
-True if @var{file} exists and is a character special file.
-
-@item -d @var{file}
-True if @var{file} exists and is a directory.
-
-@item -e @var{file}
-True if @var{file} exists.
-
-@item -f @var{file}
-True if @var{file} exists and is a regular file.
-
-@item -g @var{file}
-True if @var{file} exists and its set-group-id bit is set.
-
-@item -h @var{file}
-True if @var{file} exists and is a symbolic link.
-
-@item -k @var{file}
-True if @var{file} exists and its "sticky" bit is set.
-
-@item -p @var{file}
-True if @var{file} exists and is a named pipe (FIFO).
-
-@item -r @var{file}
-True if @var{file} exists and is readable.
-
-@item -s @var{file}
-True if @var{file} exists and has a size greater than zero.
-
-@item -t @var{fd}
-True if file descriptor @var{fd} is open and refers to a terminal.
-
-@item -u @var{file}
-True if @var{file} exists and its set-user-id bit is set.
-
-@item -w @var{file}
-True if @var{file} exists and is writable.
-
-@item -x @var{file}
-True if @var{file} exists and is executable.
-
-@item -O @var{file}
-True if @var{file} exists and is owned by the effective user id.
-
-@item -G @var{file}
-True if @var{file} exists and is owned by the effective group id.
-
-@item -L @var{file}
-True if @var{file} exists and is a symbolic link.
-
-@item -S @var{file}
-True if @var{file} exists and is a socket.
-
-@item -N @var{file}
-True if @var{file} exists and has been modified since it was last read.
-
-@item @var{file1} -nt @var{file2}
-True if @var{file1} is newer (according to modification date)
-than @var{file2}, or if @var{file1} exists and @var{file2} does not.
-
-@item @var{file1} -ot @var{file2}
-True if @var{file1} is older than @var{file2},
-or if @var{file2} exists and @var{file1} does not.
-
-@item @var{file1} -ef @var{file2}
-True if @var{file1} and @var{file2} refer to the same device and
-inode numbers.
-
-@item -o @var{optname}
-True if shell option @var{optname} is enabled.
-The list of options appears in the description of the @option{-o}
-option to the @code{set} builtin (@pxref{The Set Builtin}).
-
-@item -z @var{string}
-True if the length of @var{string} is zero.
-
-@item -n @var{string}
-@itemx @var{string}
-True if the length of @var{string} is non-zero.
-
-@item @var{string1} == @var{string2}
-True if the strings are equal.
-@samp{=} may be used in place of @samp{==} for strict @sc{posix} compliance.
-
-@item @var{string1} != @var{string2}
-True if the strings are not equal.
-
-@item @var{string1} < @var{string2}
-True if @var{string1} sorts before @var{string2} lexicographically
-in the current locale.
-
-@item @var{string1} > @var{string2}
-True if @var{string1} sorts after @var{string2} lexicographically
-in the current locale.
-
-@item @var{arg1} OP @var{arg2}
-@code{OP} is one of 
-@samp{-eq}, @samp{-ne}, @samp{-lt}, @samp{-le}, @samp{-gt}, or @samp{-ge}.
-These arithmetic binary operators return true if @var{arg1}
-is equal to, not equal to, less than, less than or equal to,
-greater than, or greater than or equal to @var{arg2},
-respectively.  @var{Arg1} and @var{arg2}
-may be positive or negative integers.
-
-@end table
-
-@node Shell Arithmetic
-@section Shell Arithmetic
-@cindex arithmetic, shell
-@cindex shell arithmetic
-@cindex expressions, arithmetic
-@cindex evaluation, arithmetic
-@cindex arithmetic evaluation
-
-The shell allows arithmetic expressions to be evaluated, as one of
-the shell expansions or by the @code{let} and the @option{-i} option
-to the @code{declare} builtins.
-
-Evaluation is done in fixed-width integers with no check for overflow,
-though division by 0 is trapped and flagged as an error.
-The operators and their precedence, associativity, and values
-are the same as in the C language.
-The following list of operators is grouped into levels of
-equal-precedence operators.
-The levels are listed in order of decreasing precedence. 
-
-@table @code
-
-@item @var{id}++ @var{id}--
-variable post-increment and post-decrement 
-
-@item ++@var{id} --@var{id}
-variable pre-increment and pre-decrement
-
-@item - +
-unary minus and plus
-
-@item ! ~
-logical and bitwise negation
-
-@item **
-exponentiation
-
-@item * / %
-multiplication, division, remainder
-
-@item + -
-addition, subtraction
-
-@item << >>
-left and right bitwise shifts
-
-@item <= >= < >
-comparison
-
-@item == !=
-equality and inequality
-
-@item &
-bitwise AND
-
-@item ^
-bitwise exclusive OR
-
-@item |
-bitwise OR
-
-@item &&
-logical AND
-
-@item ||
-logical OR
-
-@item expr ? expr : expr
-conditional operator
-
-@item = *= /= %= += -= <<= >>= &= ^= |=
-assignment
-
-@item expr1 , expr2
-comma
-@end table
-
-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.
-A shell variable that is null or unset evaluates to 0 when referenced
-by name without using the parameter expansion syntax.
-The value of a variable is evaluated as an arithmetic expression
-when it is referenced, or when a variable which has been given the  
-@var{integer} attribute using @samp{declare -i} is assigned a value.
-A null value evaluates to 0.
-A shell variable need not have its integer attribute turned on
-to be used in an expression.
-
-Constants with a leading 0 are interpreted as octal numbers.
-A leading @samp{0x} or @samp{0X} denotes hexadecimal.  Otherwise,
-numbers take the form [@var{base}@code{#}]@var{n}, where @var{base}
-is a decimal number between 2 and 64 representing the arithmetic
-base, and @var{n} is a number in that base.  If @var{base}@code{#} is
-omitted, then base 10 is used.
-The digits greater than 9 are represented by the lowercase letters,
-the uppercase letters, @samp{@@}, and @samp{_}, in that order.
-If @var{base} is less than or equal to 36, lowercase and uppercase
-letters may be used interchangably to represent numbers between 10
-and 35.
-
-Operators are evaluated in order of precedence.  Sub-expressions in
-parentheses are evaluated first and may override the precedence
-rules above.
-
-@node Aliases
-@section Aliases
-@cindex alias expansion
-
-@var{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 @code{alias} and @code{unalias} builtin commands.
-
-The first word of each simple command, if unquoted, is checked to see
-if it has an alias.
-If so, that word is replaced by the text of the alias.
-The characters @samp{/}, @samp{$}, @samp{`}, @samp{=} and any of the
-shell metacharacters or quoting characters listed above may not appear
-in an alias name.
-The replacement text may contain any valid
-shell input, including shell metacharacters.
-The first word of the replacement text is tested for
-aliases, but a word that is identical to an alias being expanded
-is not expanded a second time.
-This means that one may alias @code{ls} to @code{"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
-space or tab character, then the next command word following the
-alias is also checked for alias expansion.
-
-Aliases are created and listed with the @code{alias}
-command, and removed with the @code{unalias} command.
-
-There is no mechanism for using arguments in the replacement text,
-as in @code{csh}.
-If arguments are needed, a shell function should be used
-(@pxref{Shell Functions}).
-
-Aliases are not expanded when the shell is not interactive,
-unless the @code{expand_aliases} shell option is set using
-@code{shopt} (@pxref{Bash Builtins}).
-
-The rules concerning the definition and use of aliases are
-somewhat confusing.  Bash
-always reads at least one complete line
-of input before executing any
-of the commands on that line.  Aliases are expanded when a
-command is read, not when it is executed.  Therefore, an
-alias definition appearing on the same line as another
-command does not take effect until the next line of input is read.
-The commands following the alias definition
-on that line are not affected by the new alias.
-This behavior is also an issue when functions are executed.
-Aliases are expanded when a function definition is read,
-not when the function is executed, because a function definition
-is itself a 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 @code{alias}
-in compound commands.
-
-For almost every purpose, shell functions are preferred over aliases.
-
-@node Arrays
-@section Arrays
-@cindex arrays
-
-Bash provides one-dimensional array variables.  Any variable may be used as
-an array; the @code{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 zero-based.
-
-An array is created automatically if any variable is assigned to using
-the syntax
-@example
-name[@var{subscript}]=@var{value}
-@end example
-
-@noindent
-The @var{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
-@example
-declare -a @var{name}
-@end example
-@noindent
-The syntax
-@example
-declare -a @var{name}[@var{subscript}]
-@end example
-@noindent
-is also accepted; the @var{subscript} is ignored.  Attributes may be
-specified for an array variable using the @code{declare} and
-@code{readonly} builtins.  Each attribute applies to all members of
-an array.
-
-Arrays are assigned to using compound assignments of the form
-@example
-name=(value@var{1} @dots{} value@var{n})
-@end example
-@noindent
-where each
-@var{value} is of the form @code{[[@var{subscript}]=]}@var{string}.  If
-the optional subscript is 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 @code{declare}
-builtin.  Individual array elements may be assigned to using the
-@code{name[}@var{subscript}@code{]=}@var{value} syntax introduced above.
-
-Any element of an array may be referenced using
-@code{$@{name[}@var{subscript}@code{]@}}.
-The braces are required to avoid
-conflicts with the shell's filename expansion operators.  If the
-@var{subscript} is @samp{@@} or @samp{*}, the word expands to all members
-of the array @var{name}.  These subscripts differ only when the word
-appears within double quotes.  If the word is double-quoted,
-@code{$@{name[*]@}} expands to a single word with
-the value of each array member separated by the first character of the
-@env{IFS} variable, and @code{$@{name[@@]@}} expands each element of
-@var{name} to a separate word.  When there are no array members,
-@code{$@{name[@@]@}} expands to nothing.  This is analogous to the
-expansion of the special parameters @samp{@@} and @samp{*}. 
-@code{$@{#name[}@var{subscript}@code{]@}} expands to the length of
-@code{$@{name[}@var{subscript}@code{]@}}.
-If @var{subscript} is @samp{@@} or
-@samp{*}, the expansion is the number of elements in the array. 
-Referencing an array variable without a subscript is equivalent to
-referencing element zero. 
-
-The @code{unset} builtin is used to destroy arrays.
-@code{unset} @var{name}[@var{subscript}]
-destroys the array element at index @var{subscript}.
-@code{unset} @var{name}, where @var{name} is an array, removes the
-entire array. A subscript of @samp{*} or @samp{@@} also removes the
-entire array.
-
-The @code{declare}, @code{local}, and @code{readonly}
-builtins each accept a @option{-a}
-option to specify an array.  The @code{read}
-builtin accepts a @option{-a}
-option to assign a list of words read from the standard input
-to an array, and can read values from the standard input into
-individual array elements.  The @code{set} and @code{declare}
-builtins display array values in a way that allows them to be
-reused as input.
-
-@node The Directory Stack
-@section The Directory Stack
-@cindex directory stack
-
-@menu
-* Directory Stack Builtins::		Bash builtin commands to manipulate
-					the directory stack.
-@end menu
-
-The directory stack is a list of recently-visited directories.  The
-@code{pushd} builtin adds directories to the stack as it changes
-the current directory, and the @code{popd} builtin removes specified
-directories from the stack and changes the current directory to
-the directory removed.  The @code{dirs} builtin displays the contents
-of the directory stack.
-
-The contents of the directory stack are also visible
-as the value of the @env{DIRSTACK} shell variable.
-
-@node Directory Stack Builtins
-@subsection Directory Stack Builtins
-
-@table @code
-
-@item dirs
-@btindex dirs
-@example
-dirs [+@var{N} | -@var{N}] [-clpv]
-@end example
-Display the list of currently remembered directories.  Directories
-are added to the list with the @code{pushd} command; the
-@code{popd} command removes directories from the list.
-@table @code
-@item +@var{N}
-Displays the @var{N}th directory (counting from the left of the
-list printed by @code{dirs} when invoked without options), starting
-with zero.
-@item -@var{N}
-Displays the @var{N}th directory (counting from the right of the
-list printed by @code{dirs} when invoked without options), starting
-with zero.
-@item -c
-Clears the directory stack by deleting all of the elements.
-@item -l
-Produces a longer listing; the default listing format uses a 
-tilde to denote the home directory.
-@item -p
-Causes @code{dirs} to print the directory stack with one entry per
-line.
-@item -v
-Causes @code{dirs} to print the directory stack with one entry per
-line, prefixing each entry with its index in the stack.
-@end table
-
-@item popd
-@btindex popd
-@example
-popd [+@var{N} | -@var{N}] [-n]
-@end example
-
-Remove the top entry from the directory stack, and @code{cd}
-to the new top directory.
-When no arguments are given, @code{popd}
-removes the top directory from the stack and
-performs a @code{cd} to the new top directory.  The
-elements are numbered from 0 starting at the first directory listed with
-@code{dirs}; i.e., @code{popd} is equivalent to @code{popd +0}.
-@table @code
-@item +@var{N}
-Removes the @var{N}th directory (counting from the left of the
-list printed by @code{dirs}), starting with zero.
-@item -@var{N}
-Removes the @var{N}th directory (counting from the right of the
-list printed by @code{dirs}), starting with zero.
-@item -n
-Suppresses the normal change of directory when removing directories
-from the stack, so that only the stack is manipulated.
-@end table
-
-@btindex pushd
-@item pushd
-@example
-pushd [@var{dir} | @var{+N} | @var{-N}] [-n]
-@end example
-
-Save the current directory on the top of the directory stack
-and then @code{cd} to @var{dir}.
-With no arguments, @code{pushd} exchanges the top two directories.
-
-@table @code
-@item +@var{N}
-Brings the @var{N}th directory (counting from the left of the
-list printed by @code{dirs}, starting with zero) to the top of
-the list by rotating the stack.
-@item -@var{N}
-Brings the @var{N}th directory (counting from the right of the
-list printed by @code{dirs}, starting with zero) to the top of
-the list by rotating the stack.
-@item -n
-Suppresses the normal change of directory when adding directories
-to the stack, so that only the stack is manipulated.
-@item @var{dir}
-Makes the current working directory be the top of the stack, and then
-executes the equivalent of `@code{cd} @var{dir}'.
-@code{cd}s to @var{dir}.
-@end table
-
-@end table
-
-@node Printing a Prompt
-@section Controlling the Prompt
-@cindex prompting
-
-The value of the variable @env{PROMPT_COMMAND} is examined just before
-Bash prints each primary prompt.  If @env{PROMPT_COMMAND} is set and
-has a non-null value, then the
-value is executed just as if it had been typed on the command line.
-
-In addition, the following table describes the special characters which
-can appear in the prompt variables:
-
-@table @code
-@item \a
-A bell character.
-@item \d
-The date, in "Weekday Month Date" format (e.g., "Tue May 26").
-@item \D@{@var{format}@}
-The @var{format} is passed to @code{strftime}(3) and the result is inserted
-into the prompt string; an empty @var{format} results in a locale-specific
-time representation.  The braces are required.
-@item \e
-An escape character.
-@item \h
-The hostname, up to the first `.'.
-@item \H
-The hostname.
-@item \j
-The number of jobs currently managed by the shell.
-@item \l
-The basename of the shell's terminal device name.
-@item \n
-A newline.
-@item \r
-A carriage return.
-@item \s
-The name of the shell, the basename of @code{$0} (the portion
-following the final slash).
-@item \t
-The time, in 24-hour HH:MM:SS format.
-@item \T
-The time, in 12-hour HH:MM:SS format.
-@item \@@
-The time, in 12-hour am/pm format.
-@item \A
-The time, in 24-hour HH:MM format.
-@item \u
-The username of the current user.
-@item \v
-The version of Bash (e.g., 2.00)          
-@item \V
-The release of Bash, version + patchlevel (e.g., 2.00.0)
-@item \w
-The current working directory, with @env{$HOME} abbreviated with a tilde.
-@item \W
-The basename of @env{$PWD}, with @env{$HOME} abbreviated with a tilde.
-@item \!
-The history number of this command.
-@item \#
-The command number of this command.
-@item \$
-If the effective uid is 0, @code{#}, otherwise @code{$}.
-@item \@var{nnn}
-The character whose ASCII code is the octal value @var{nnn}.
-@item \\
-A backslash.
-@item \[
-Begin a sequence of non-printing characters.  This could be used to
-embed a terminal control sequence into the prompt.
-@item \]
-End a sequence of non-printing characters.
-@end table
-
-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
-(@pxref{Bash History Facilities}), 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
-@code{promptvars} shell option (@pxref{Bash Builtins}).
-
-@node The Restricted Shell
-@section The Restricted Shell
-@cindex restricted shell
-
-If Bash is started with the name @code{rbash}, or the
-@option{--restricted}
-or
-@option{-r}
-option is supplied at invocation, the shell becomes restricted.
-A restricted shell is used to
-set up an environment more controlled than the standard shell.
-A restricted shell behaves identically to @code{bash}
-with the exception that the following are disallowed or not performed:
-
-@itemize @bullet
-@item
-Changing directories with the @code{cd} builtin.
-@item
-Setting or unsetting the values of the @env{SHELL}, @env{PATH},
-@env{ENV}, or @env{BASH_ENV} variables.
-@item
-Specifying command names containing slashes.
-@item
-Specifying a filename containing a slash as an argument to the @code{.}
-builtin command.
-@item
-Specifying a filename containing a slash as an argument to the @option{-p}
-option to the @code{hash} builtin command.
-@item
-Importing function definitions from the shell environment at startup.
-@item
-Parsing the value of @env{SHELLOPTS} from the shell environment at startup.
-@item
-Redirecting output using the @samp{>}, @samp{>|}, @samp{<>}, @samp{>&},
-@samp{&>}, and @samp{>>} redirection operators.
-@item
-Using the @code{exec} builtin to replace the shell with another command.
-@item
-Adding or deleting builtin commands with the
-@option{-f} and @option{-d} options to the @code{enable} builtin.
-@item
-Using the @code{enable} builtin command to enable disabled shell builtins.
-@item
-Specifying the @option{-p} option to the @code{command} builtin.
-@item
-Turning off restricted mode with @samp{set +r} or @samp{set +o restricted}.
-@end itemize
-
-These restrictions are enforced after any startup files are read.
-
-When a command that is found to be a shell script is executed
-(@pxref{Shell Scripts}), @code{rbash} turns off any restrictions in
-the shell spawned to execute the script.
-
-@node Bash POSIX Mode
-@section Bash POSIX Mode
-@cindex POSIX Mode
-
-Starting Bash with the @option{--posix} command-line option or executing
-@samp{set -o posix} while Bash is running will cause Bash to conform more
-closely to the @sc{posix} 1003.2 standard by changing the behavior to
-match that specified by @sc{posix} in areas where the Bash default differs.
-
-When invoked as @code{sh}, Bash enters @sc{posix} mode after reading the
-startup files.
-
-The following list is what's changed when `@sc{posix} mode' is in effect:
-
-@enumerate
-@item
-When a command in the hash table no longer exists, Bash will re-search
-@env{$PATH} to find the new location.  This is also available with
-@samp{shopt -s checkhash}.
-
-@item
-The message printed by the job control code and builtins when a job
-exits with a non-zero status is `Done(status)'.
-
-@item
-The message printed by the job control code and builtins when a job
-is stopped is `Stopped(@var{signame})', where @var{signame} is, for
-example, @code{SIGTSTP}.
-
-@item
-Reserved words may not be aliased.
-
-@item
-The @sc{posix} 1003.2 @env{PS1} and @env{PS2} expansions of @samp{!} to
-the history number and @samp{!!} to @samp{!} are enabled,
-and parameter expansion is performed on the values of @env{PS1} and
-@env{PS2} regardless of the setting of the @code{promptvars} option.
-
-@item
-The @sc{posix} 1003.2 startup files are executed (@env{$ENV}) rather than
-the normal Bash files.
-
-@item
-Tilde expansion is only performed on assignments preceding a command
-name, rather than on all assignment statements on the line.
-
-@item
-The default history file is @file{~/.sh_history} (this is the
-default value of @env{$HISTFILE}).
-
-@item
-The output of @samp{kill -l} prints all the signal names on a single line,
-separated by spaces, without the @samp{SIG} prefix.
-
-@item
-The @code{kill} builtin does not accept signal names with a @samp{SIG}
-prefix.
-
-@item
-Non-interactive shells exit if @var{filename} in @code{.} @var{filename}
-is not found.
-
-@item
-Non-interactive shells exit if a syntax error in an arithmetic expansion
-results in an invalid expression.
-
-@item
-Redirection operators do not perform filename expansion on the word
-in the redirection unless the shell is interactive.
-
-@item
-Redirection operators do not perform word splitting on the word in the
-redirection.
-
-@item
-Function names must be valid shell @code{name}s.  That is, they may not
-contain characters other than letters, digits, and underscores, and
-may not start with a digit.  Declaring a function with an invalid name
-causes a fatal syntax error in non-interactive shells.
-
-@item
-@sc{posix} 1003.2 `special' builtins are found before shell functions
-during command lookup.
-
-@item
-If a @sc{posix} 1003.2 special builtin returns an error status, a
-non-interactive shell exits.  The fatal errors are those listed in
-the POSIX.2 standard, and include things like passing incorrect options,
-redirection errors, variable assignment errors for assignments preceding
-the command name, and so on.
-
-@item
-If the @code{cd} builtin finds a directory to change to
-using @env{$CDPATH}, the
-value it assigns to the @env{PWD} variable does not contain any
-symbolic links, as if @samp{cd -P} had been executed.
-
-@item
-If @env{CDPATH} is set, the @code{cd} builtin will not implicitly
-append the current directory to it.  This means that @code{cd} will
-fail if no valid directory name can be constructed from
-any of the entries in @env{$CDPATH}, even if the a directory with
-the same name as the name given as an argument to @code{cd} exists
-in the current directory.
-
-@item
-A non-interactive shell exits with an error status if a variable
-assignment error occurs when no command name follows the assignment
-statements.
-A variable assignment error occurs, for example, when trying to assign
-a value to a readonly variable.
-
-@item
-A non-interactive shell exits with an error status if the iteration
-variable in a @code{for} statement or the selection variable in a
-@code{select} statement is a readonly variable.
-
-@item
-Process substitution is not available.
-
-@item
-Assignment statements preceding @sc{posix} 1003.2 special builtins
-persist in the shell environment after the builtin completes.
-
-@item
-Assignment statements preceding shell function calls persist in the
-shell environment after the function returns, as if a @sc{posix}
-special builtin command had been executed.
-
-@item
-The @code{export} and @code{readonly} builtin commands display their
-output in the format required by @sc{posix} 1003.2.
-
-@item
-The @code{trap} builtin displays signal names without the leading
-@code{SIG}.
-
-@item
-The @code{trap} builtin doesn't check the first argument for a possible
-signal specification and revert the signal handling to the original
-disposition if it is.  If users want to reset the handler for a given
-signal to the original disposition, they should use @samp{-} as the
-first argument.
-
-@item
-The @code{.} and @code{source} builtins do not search the current directory
-for the filename argument if it is not found by searching @env{PATH}.
-
-@item
-Subshells spawned to execute command substitutions inherit the value of
-the @option{-e} option from the parent shell.  When not in @sc{posix} mode,
-Bash clears the @option{-e} option in such subshells.
-
-@item
-Alias expansion is always enabled, even in non-interactive shells.
-
-@item
-When the @code{alias} builtin displays alias definitions, it does not
-display them with a leading @samp{alias } unless the @option{-p} option
-is supplied.
-
-@item
-When the @code{set} builtin is invoked without options, it does not display
-shell function names and definitions.
-
-@item
-When the @code{set} builtin is invoked without options, it displays
-variable values without quotes, unless they contain shell metacharacters,
-even if the result contains nonprinting characters.
-
-@item
-When the @code{cd} builtin is invoked in @var{logical} mode, and the pathname
-constructed from @code{$PWD} and the directory name supplied as an argument
-does not refer to an existing directory, @code{cd} will fail instead of
-falling back to @var{physical} mode.
-@end enumerate
-
-There is other @sc{posix} 1003.2 behavior that Bash does not implement.
-Specifically:
-
-@enumerate
-@item
-Assignment statements affect the execution environment of all
-builtins, not just special ones.
-
-@item
-When a subshell is created to execute a shell script with execute permission,
-but without a leading @samp{#!}, Bash sets @code{$0} to the full pathname of
-the script as found by searching @code{$PATH}, rather than the command as
-typed by the user.
-
-@item
-When using @samp{.} to source a shell script found in @code{$PATH}, bash
-checks execute permission bits rather than read permission bits, just as
-if it were searching for a command.
-
-@end enumerate
-
-@node Job Control
-@chapter Job Control
-
-This chapter discusses what job control is, how it works, and how
-Bash allows you to access its facilities.
-
-@menu
-* Job Control Basics::		How job control works.
-* Job Control Builtins::	Bash builtin commands used to interact
-				with job control.
-* Job Control Variables::	Variables Bash uses to customize job
-				control.
-@end menu
-
-@node Job Control Basics
-@section Job Control Basics
-@cindex job control
-@cindex foreground
-@cindex background
-@cindex suspending jobs
-
-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 @var{job} with each pipeline.  It keeps a
-table of currently executing jobs, which may be listed with the
-@code{jobs} command.  When Bash starts a job
-asynchronously, it prints a line that looks
-like:
-@example
-[1] 25647
-@end example
-@noindent
-indicating that this job is job number 1 and that the process @sc{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 @var{job} abstraction as the
-basis for job control. 
-
-To facilitate the implementation of the user interface to job
-control, the operating system maintains the notion of a current terminal
-process group @sc{id}.  Members of this process group (processes whose
-process group @sc{id} is equal to the current terminal process group
-@sc{id}) receive keyboard-generated signals such as @code{SIGINT}. 
-These processes are said to be in the foreground.  Background
-processes are those whose process group @sc{id} differs from the
-terminal'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 @code{SIGTTIN}
-(@code{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
-@var{suspend} character (typically @samp{^Z}, Control-Z) while a
-process is running causes that process to be stopped and returns
-control to Bash.  Typing the @var{delayed suspend} character
-(typically @samp{^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 then manipulates the state of
-this job, using the @code{bg} command to continue it in the
-background, the @code{fg} command to continue it in the
-foreground, or the @code{kill} command to kill it.  A @samp{^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 @samp{%} introduces a job name.
-
-Job number @code{n} may be referred to as @samp{%n}.
-The symbols @samp{%%} and
-@samp{%+} 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 @samp{%-}.  In output
-pertaining to jobs (e.g., the output of the @code{jobs} command),
-the current job is always flagged with a @samp{+}, and the
-previous job with a @samp{-}. 
-
-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, @samp{%ce} refers
-to a stopped @code{ce} job. Using @samp{%?ce}, on the
-other hand, refers to any job containing the string @samp{ce} in
-its command line.  If the prefix or substring matches more than one job,
-Bash reports an error.
-
-Simply naming a job can be used to bring it into the foreground:
-@samp{%1} is a synonym for @samp{fg %1}, bringing job 1 from the
-background into the foreground.  Similarly, @samp{%1 &} resumes
-job 1 in the background, equivalent to @samp{bg %1}
-
-The shell learns immediately whenever a job changes state. 
-Normally, Bash waits until it is about to print a prompt
-before reporting changes in a job's status so as to not interrupt
-any other output.
-If the @option{-b} option to the @code{set} builtin is enabled,
-Bash reports such changes immediately (@pxref{The Set Builtin}).
-Any trap on @code{SIGCHLD} is executed for each child process
-that exits.
-
-If an attempt to exit Bash is made while jobs are stopped, the
-shell prints a message warning that there are stopped jobs.
-The @code{jobs} command may then be used to inspect their status.
-If a second attempt to exit is made without an intervening command,
-Bash does not print another warning, and the stopped jobs are terminated.
-
-@node Job Control Builtins
-@section Job Control Builtins
-
-@table @code
-
-@item bg
-@btindex bg
-@example
-bg [@var{jobspec}]
-@end example
-Resume the suspended job @var{jobspec} in the background, as if it
-had been started with @samp{&}.
-If @var{jobspec} is not supplied, the current job is used.
-The return status is zero unless it is run when job control is not
-enabled, or, when run with job control enabled, if @var{jobspec} was
-not found or @var{jobspec} specifies a job that was started without
-job control.
-
-@item fg
-@btindex fg
-@example
-fg [@var{jobspec}]
-@end example
-Resume the job @var{jobspec} in the foreground and make it the current job.
-If @var{jobspec} is not supplied, the current job is used.
-The return status is that of the command placed into the foreground,
-or non-zero if run when job control is disabled or, when run with
-job control enabled, @var{jobspec} does not specify a valid job or
-@var{jobspec} specifies a job that was started without job control.
-
-@item jobs
-@btindex jobs
-@example
-jobs [-lnprs] [@var{jobspec}]
-jobs -x @var{command} [@var{arguments}]
-@end example
-
-The first form lists the active jobs.  The options have the
-following meanings:
-
-@table @code
-@item -l
-List process @sc{id}s in addition to the normal information.
-
-@item -n
-Display information only about jobs that have changed status since
-the user was last notified of their status.
-
-@item -p
-List only the process @sc{id} of the job's process group leader.
-
-@item -r
-Restrict output to running jobs.
-
-@item -s
-Restrict output to stopped jobs.
-@end table
-
-If @var{jobspec} is given,
-output is restricted to information about that job. 
-If @var{jobspec} is not supplied, the status of all jobs is
-listed.
-
-If the @option{-x} option is supplied, @code{jobs} replaces any
-@var{jobspec} found in @var{command} or @var{arguments} with the
-corresponding process group @sc{id}, and executes @var{command},
-passing it @var{argument}s, returning its exit status. 
-
-@item kill
-@btindex kill
-@example
-kill [-s @var{sigspec}] [-n @var{signum}] [-@var{sigspec}] @var{jobspec} or @var{pid}
-kill -l [@var{exit_status}]
-@end example
-Send a signal specified by @var{sigspec} or @var{signum} to the process
-named by job specification @var{jobspec} or process @sc{id} @var{pid}.
-@var{sigspec} is either a case-insensitive signal name such as
-@code{SIGINT} (with or without the @code{SIG} prefix)
-or a signal number; @var{signum} is a signal number.
-If @var{sigspec} and @var{signum} are not present, @code{SIGTERM} is used.
-The @option{-l} option lists the signal names.
-If any arguments are supplied when @option{-l} is given, the names of the
-signals corresponding to the arguments are listed, and the return status
-is zero.
-@var{exit_status} is a number specifying a signal number or the exit
-status of a process terminated by a signal.
-The return status is zero if at least one signal was successfully sent,
-or non-zero if an error occurs or an invalid option is encountered.
-
-@item wait
-@btindex wait
-@example
-wait [@var{jobspec} or @var{pid}]
-@end example
-Wait until the child process specified by process @sc{id} @var{pid} or job
-specification @var{jobspec} exits and return the exit status of the last
-command waited for.
-If a job spec is given, all processes in the job are waited for.
-If no arguments are given, all currently active child processes are
-waited for, and the return status is zero.
-If neither @var{jobspec} nor @var{pid} specifies an active child process
-of the shell, the return status is 127.
-
-@item disown
-@btindex disown
-@example
-disown [-ar] [-h] [@var{jobspec} @dots{}]
-@end example
-Without options, each @var{jobspec} is removed from the table of
-active jobs.
-If the @option{-h} option is given, the job is not removed from the table,
-but is marked so that @code{SIGHUP} is not sent to the job if the shell
-receives a @code{SIGHUP}.
-If @var{jobspec} is not present, and neither the @option{-a} nor @option{-r}
-option is supplied, the current job is used.
-If no @var{jobspec} is supplied, the @option{-a} option means to remove or
-mark all jobs; the @option{-r} option without a @var{jobspec}
-argument restricts operation to running jobs.
-
-@item suspend
-@btindex suspend
-@example
-suspend [-f]
-@end example
-Suspend the execution of this shell until it receives a
-@code{SIGCONT} signal.  The @option{-f} option means to suspend
-even if the shell is a login shell.
-
-@end table
-
-When job control is not active, the @code{kill} and @code{wait}
-builtins do not accept @var{jobspec} arguments.  They must be
-supplied process @sc{id}s.
-
-@node Job Control Variables
-@section Job Control Variables
-
-@vtable @code
-
-@item auto_resume
-This variable controls how the shell interacts with the user and
-job control.  If this variable exists then single word simple
-commands without redirections are treated as candidates for resumption
-of an existing job.  There is no ambiguity allowed; if there is
-more than one job beginning with the string typed, then
-the most recently accessed job will be selected.
-The name of a stopped job, in this context, is the command line
-used to start it.  If this variable is set to the value @samp{exact},
-the string supplied must match the name of a stopped job exactly;
-if set to @samp{substring},
-the string supplied needs to match a substring of the name of a
-stopped job.  The @samp{substring} value provides functionality
-analogous to the @samp{%?} job @sc{id} (@pxref{Job Control Basics}).
-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 @samp{%} job @sc{id}.
-
-@end vtable
-
-@set readline-appendix
-@set history-appendix
-@cindex Readline, how to use
-@include rluser.texi
-@cindex History, how to use
-@include hsuser.texi
-@clear readline-appendix
-@clear history-appendix
-
-@node Installing Bash
-@chapter Installing Bash
-
-This chapter provides basic instructions for installing Bash on
-the various supported platforms.  The distribution supports the
-@sc{gnu} operating systems, nearly every version of Unix, and several
-non-Unix systems such as BeOS and Interix.
-Other independent ports exist for
-@sc{ms-dos}, @sc{os/2}, and Windows platforms.
-
-@menu
-* Basic Installation::	Installation instructions.
-
-* Compilers and Options::	How to set special options for various
-				systems.
-
-* Compiling For Multiple Architectures::	How to compile Bash for more
-						than one kind of system from
-						the same source tree.
-
-* Installation Names::	How to set the various paths used by the installation.
-
-* Specifying the System Type::	How to configure Bash for a particular system.
-
-* Sharing Defaults::	How to share default configuration values among GNU
-			programs.
-
-* Operation Controls::	Options recognized by the configuration program.
-
-* Optional Features::	How to enable and disable optional features when
-			building Bash.
-@end menu
-
-@node Basic Installation
-@section Basic Installation
-@cindex installation
-@cindex configuration
-@cindex Bash installation
-@cindex Bash configuration
-
-These are installation instructions for Bash.
-
-The simplest way to compile Bash is:
-
-@enumerate
-@item
-@code{cd} to the directory containing the source code and type
-@samp{./configure} to configure Bash for your system.  If you're
-using @code{csh} on an old version of System V, you might need to
-type @samp{sh ./configure} instead to prevent @code{csh} from trying
-to execute @code{configure} itself.
-
-Running @code{configure} takes some time.
-While running, it prints messages telling which features it is
-checking for.
-
-@item
-Type @samp{make} to compile Bash and build the @code{bashbug} bug
-reporting script.
-
-@item
-Optionally, type @samp{make tests} to run the Bash test suite.
-
-@item
-Type @samp{make install} to install @code{bash} and @code{bashbug}.
-This will also install the manual pages and Info file.
-
-@end enumerate
-
-The @code{configure} shell script attempts to guess correct
-values for various system-dependent variables used during
-compilation.  It uses those values to create a @file{Makefile} in
-each directory of the package (the top directory, the
-@file{builtins}, @file{doc}, and @file{support} directories,
-each directory under @file{lib}, and several others).  It also creates a
-@file{config.h} file containing system-dependent definitions. 
-Finally, it creates a shell script named @code{config.status} that you
-can run in the future to recreate the current configuration, a
-file @file{config.cache} that saves the results of its tests to
-speed up reconfiguring, and a file @file{config.log} containing
-compiler output (useful mainly for debugging @code{configure}). 
-If at some point
-@file{config.cache} contains results you don't want to keep, you
-may remove or edit it. 
-
-To find out more about the options and arguments that the
-@code{configure} script understands, type 
-
-@example
-bash-2.04$ ./configure --help
-@end example
-
-@noindent
-at the Bash prompt in your Bash source directory.
-
-If you need to do unusual things to compile Bash, please
-try to figure out how @code{configure} could check whether or not
-to do them, and mail diffs or instructions to
-@email{bash-maintainers@@gnu.org} so they can be
-considered for the next release.
-
-The file @file{configure.in} is used to create @code{configure}
-by a program called Autoconf.  You only need
-@file{configure.in} if you want to change it or regenerate
-@code{configure} using a newer version of Autoconf.  If
-you do this, make sure you are using Autoconf version 2.50 or
-newer.
-
-You can remove the program binaries and object files from the
-source code directory by typing @samp{make clean}.  To also remove the
-files that @code{configure} created (so you can compile Bash for
-a different kind of computer), type @samp{make distclean}.
-
-@node Compilers and Options
-@section Compilers and Options
-
-Some systems require unusual options for compilation or linking
-that the @code{configure} script does not know about.  You can
-give @code{configure} initial values for variables by setting
-them in the environment.  Using a Bourne-compatible shell, you
-can do that on the command line like this:
-
-@example
-CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure
-@end example
-
-On systems that have the @code{env} program, you can do it like this:
-
-@example
-env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure
-@end example
-
-The configuration process uses GCC to build Bash if it
-is available.
-
-@node Compiling For Multiple Architectures
-@section Compiling For Multiple Architectures
-
-You can compile Bash for more than one kind of computer at the
-same time, by placing the object files for each architecture in their
-own directory.  To do this, you must use a version of @code{make} that
-supports the @code{VPATH} variable, such as GNU @code{make}.
-@code{cd} to the
-directory where you want the object files and executables to go and run
-the @code{configure} script from the source directory.  You may need to
-supply the @option{--srcdir=PATH} argument to tell @code{configure} where the
-source files are.  @code{configure} automatically checks for the
-source code in the directory that @code{configure} is in and in `..'.
-
-If you have to use a @code{make} that does not supports the @code{VPATH}
-variable, you can compile Bash for one architecture at a
-time in the source code directory.  After you have installed
-Bash for one architecture, use @samp{make distclean} before
-reconfiguring for another architecture.
-
-Alternatively, if your system supports symbolic links, you can use the
-@file{support/mkclone} script to create a build tree which has
-symbolic links back to each file in the source directory.  Here's an
-example that creates a build directory in the current directory from a
-source directory @file{/usr/gnu/src/bash-2.0}:
-
-@example
-bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 .
-@end example
-
-@noindent
-The @code{mkclone} script requires Bash, so you must have already built
-Bash for at least one architecture before you can create build
-directories for other architectures.
-
-@node Installation Names
-@section Installation Names
-
-By default, @samp{make install} will install into
-@file{/usr/local/bin}, @file{/usr/local/man}, etc.  You can
-specify an installation prefix other than @file{/usr/local} by
-giving @code{configure} the option @option{--prefix=@var{PATH}},
-or by specifying a value for the @code{DESTDIR} @samp{make}
-variable when running @samp{make install}.
-
-You can specify separate installation prefixes for
-architecture-specific files and architecture-independent files. 
-If you give @code{configure} the option
-@option{--exec-prefix=@var{PATH}}, @samp{make install} will use
-@var{PATH} as the prefix for installing programs and libraries.
-Documentation and other data files will still use the regular prefix. 
-
-@node Specifying the System Type
-@section Specifying the System Type
-
-There may be some features @code{configure} can not figure out
-automatically, but need to determine by the type of host Bash
-will run on.  Usually @code{configure} can figure that
-out, but if it prints a message saying it can not guess the host
-type, give it the @option{--host=TYPE} option.  @samp{TYPE} can
-either be a short name for the system type, such as @samp{sun4},
-or a canonical name with three fields: @samp{CPU-COMPANY-SYSTEM}
-(e.g., @samp{i386-unknown-freebsd4.2}).
-
-See the file @file{support/config.sub} for the possible
-values of each field. 
-
-@node Sharing Defaults
-@section Sharing Defaults
-
-If you want to set default values for @code{configure} scripts to
-share, you can create a site shell script called
-@code{config.site} that gives default values for variables like
-@code{CC}, @code{cache_file}, and @code{prefix}.  @code{configure}
-looks for @file{PREFIX/share/config.site} if it exists, then
-@file{PREFIX/etc/config.site} if it exists.  Or, you can set the
-@code{CONFIG_SITE} environment variable to the location of the site
-script.  A warning: the Bash @code{configure} looks for a site script,
-but not all @code{configure} scripts do.
-
-@node Operation Controls
-@section Operation Controls
-
-@code{configure} recognizes the following options to control how it
-operates.
-
-@table @code
-
-@item --cache-file=@var{file}
-Use and save the results of the tests in
-@var{file} instead of @file{./config.cache}.  Set @var{file} to
-@file{/dev/null} to disable caching, for debugging
-@code{configure}. 
-
-@item --help
-Print a summary of the options to @code{configure}, and exit.
-
-@item --quiet
-@itemx --silent
-@itemx -q
-Do not print messages saying which checks are being made.
-
-@item --srcdir=@var{dir}
-Look for the Bash source code in directory @var{dir}.  Usually
-@code{configure} can determine that directory automatically.
-
-@item --version
-Print the version of Autoconf used to generate the @code{configure}
-script, and exit.
-@end table
-
-@code{configure} also accepts some other, not widely used, boilerplate
-options.  @samp{configure --help} prints the complete list.
-
-@node Optional Features
-@section Optional Features
-
-The Bash @code{configure} has a number of @option{--enable-@var{feature}}
-options, where @var{feature} indicates an optional part of Bash.
-There are also several @option{--with-@var{package}} options,
-where @var{package} is something like @samp{bash-malloc} or @samp{purify}.
-To turn off the default use of a package, use
-@option{--without-@var{package}}.  To configure Bash without a feature
-that is enabled by default, use @option{--disable-@var{feature}}.
-
-Here is a complete list of the @option{--enable-} and
-@option{--with-} options that the Bash @code{configure} recognizes. 
-
-@table @code
-@item --with-afs
-Define if you are using the Andrew File System from Transarc.
-
-@item --with-bash-malloc
-Use the Bash version of
-@code{malloc} in @file{lib/malloc/malloc.c}.  This is not the same
-@code{malloc} that appears in @sc{gnu} libc, but an older version
-derived from the 4.2 @sc{bsd} @code{malloc}.  This @code{malloc} is
-very fast, but wastes some space on each allocation.
-This option is enabled by default.
-The @file{NOTES} file contains a list of systems for
-which this should be turned off, and @code{configure} disables this
-option automatically for a number of systems.
-
-@item --with-curses
-Use the curses library instead of the termcap library.  This should
-be supplied if your system has an inadequate or incomplete termcap
-database.
-
-@item --with-gnu-malloc
-A synonym for @code{--with-bash-malloc}.
-
-@item --with-installed-readline[=@var{PREFIX}]
-Define this to make Bash link with a locally-installed version of Readline
-rather than the version in @file{lib/readline}.  This works only with
-Readline 4.3 and later versions.  If @var{PREFIX} is @code{yes} or not
-supplied, @code{configure} uses the values of the make variables
-@code{includedir} and @code{libdir}, which are subdirectories of @code{prefix}
-by default, to find the installed version of Readline if it is not in
-the standard system include and library directories.
-If @var{PREFIX} is @code{no}, Bash links with the version in
-@file{lib/readline}.
-If @var{PREFIX} is set to any other value, @code{configure} treats it as
-a directory pathname and looks for
-the installed version of Readline in subdirectories of that directory
-(include files in @var{PREFIX}/@code{include} and the library in
-@var{PREFIX}/@code{lib}).
-
-@item --with-purify
-Define this to use the Purify memory allocation checker from Rational
-Software.
-
-@item --enable-minimal-config
-This produces a shell with minimal features, close to the historical
-Bourne shell.
-@end table
-
-There are several @option{--enable-} options that alter how Bash is
-compiled and linked, rather than changing run-time features.
-
-@table @code
-@item --enable-largefile
-Enable support for @uref{http://www.sas.com/standards/large_file/x_open.20Mar96.html,
-large files} if the operating system requires special compiler options
-to build programs which can access large files.  This is enabled by
-default, if the operating system provides large file support.
-
-@item --enable-profiling
-This builds a Bash binary that produces profiling information to be
-processed by @code{gprof} each time it is executed.
-
-@item --enable-static-link
-This causes Bash to be linked statically, if @code{gcc} is being used.
-This could be used to build a version to use as root's shell.
-@end table
-
-The @samp{minimal-config} option can be used to disable all of
-the following options, but it is processed first, so individual
-options may be enabled using @samp{enable-@var{feature}}. 
-
-All of the following options except for @samp{disabled-builtins} and
-@samp{xpg-echo-default} are
-enabled by default, unless the operating system does not provide the
-necessary support.
-
-@table @code
-@item --enable-alias
-Allow alias expansion and include the @code{alias} and @code{unalias}
-builtins (@pxref{Aliases}).
-
-@item --enable-arith-for-command
-Include support for the alternate form of the @code{for} command
-that behaves like the C language @code{for} statement
-(@pxref{Looping Constructs}).
-
-@item --enable-array-variables
-Include support for one-dimensional array shell variables
-(@pxref{Arrays}).
-
-@item --enable-bang-history
-Include support for @code{csh}-like history substitution
-(@pxref{History Interaction}).
-
-@item --enable-brace-expansion
-Include @code{csh}-like brace expansion
-( @code{b@{a,b@}c} @expansion{} @code{bac bbc} ).
-See @ref{Brace Expansion}, for a complete description.
-
-@item --enable-command-timing
-Include support for recognizing @code{time} as a reserved word and for
-displaying timing statistics for the pipeline following @code{time}
-(@pxref{Pipelines}).
-This allows pipelines as well as shell builtins and functions to be timed.
-
-@item --enable-cond-command
-Include support for the @code{[[} conditional command.
-(@pxref{Conditional Constructs}).
-
-@item --enable-cond-regexp
-Include support for matching POSIX regular expressions using the
-@samp{=~} binary operator in the @code{[[} conditional command.
-(@pxref{Conditional Constructs}).
-
-@item --enable-directory-stack
-Include support for a @code{csh}-like directory stack and the
-@code{pushd}, @code{popd}, and @code{dirs} builtins
-(@pxref{The Directory Stack}).
-
-@item --enable-disabled-builtins
-Allow builtin commands to be invoked via @samp{builtin xxx}
-even after @code{xxx} has been disabled using @samp{enable -n xxx}.
-See @ref{Bash Builtins}, for details of the @code{builtin} and
-@code{enable} builtin commands.
-
-@item --enable-dparen-arithmetic
-Include support for the @code{((@dots{}))} command
-(@pxref{Conditional Constructs}).
-
-@item --enable-extended-glob
-Include support for the extended pattern matching features described
-above under @ref{Pattern Matching}.
-
-@item --enable-help-builtin
-Include the @code{help} builtin, which displays help on shell builtins and
-variables (@pxref{Bash Builtins}).
-
-@item --enable-history
-Include command history and the @code{fc} and @code{history}
-builtin commands (@pxref{Bash History Facilities}).
-
-@item --enable-job-control
-This enables the job control features (@pxref{Job Control}),
-if the operating system supports them.
-
-@item --enable-multibyte
-This enables support for multibyte characters if the operating
-system provides the necessary support.
-
-@item --enable-net-redirections
-This enables the special handling of filenames of the form
-@code{/dev/tcp/@var{host}/@var{port}} and
-@code{/dev/udp/@var{host}/@var{port}}
-when used in redirections (@pxref{Redirections}).
-
-@item --enable-process-substitution
-This enables process substitution (@pxref{Process Substitution}) if
-the operating system provides the necessary support.
-
-@item --enable-prompt-string-decoding
-Turn on the interpretation of a number of backslash-escaped characters
-in the @env{$PS1}, @env{$PS2}, @env{$PS3}, and @env{$PS4} prompt
-strings.  See @ref{Printing a Prompt}, for a complete list of prompt
-string escape sequences.
-
-@item --enable-progcomp
-Enable the programmable completion facilities
-(@pxref{Programmable Completion}).
-If Readline is not enabled, this option has no effect.
-
-@item --enable-readline
-Include support for command-line editing and history with the Bash
-version of the Readline library (@pxref{Command Line Editing}).
-
-@item --enable-restricted
-Include support for a @dfn{restricted shell}.  If this is enabled, Bash,
-when called as @code{rbash}, enters a restricted mode.  See
-@ref{The Restricted Shell}, for a description of restricted mode.
-
-@item --enable-select
-Include the @code{select} builtin, which allows the generation of simple
-menus (@pxref{Conditional Constructs}).
-
-@item --enable-usg-echo-default
-A synonym for @code{--enable-xpg-echo-default}.
-
-@item --enable-xpg-echo-default
-Make the @code{echo} builtin expand backslash-escaped characters by default,
-without requiring the @option{-e} option.
-This sets the default value of the @code{xpg_echo} shell option to @code{on},
-which makes the Bash @code{echo} behave more like the version specified in
-the Single Unix Specification, version 2.
-@xref{Bash Builtins}, for a description of the escape sequences that
-@code{echo} recognizes.
-
-@end table
-
-The file @file{config-top.h} contains C Preprocessor
-@samp{#define} statements for options which are not settable from
-@code{configure}.
-Some of these are not meant to be changed; beware of the consequences if
-you do.
-Read the comments associated with each definition for more
-information about its effect.
-
-@node Reporting Bugs
-@appendix Reporting Bugs
-
-Please report all bugs you find in Bash.
-But first, you should
-make sure that it really is a bug, and that it appears in the latest
-version of Bash.
-The latest version of Bash is always available for FTP from
-@uref{ftp://ftp.gnu.org/pub/bash/}.
-
-Once you have determined that a bug actually exists, use the
-@code{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 @email{bug-bash@@gnu.org} or posted to the Usenet
-newsgroup @code{gnu.bash.bug}.
-
-All bug reports should include:
-@itemize @bullet
-@item
-The version number of Bash.
-@item
-The hardware and operating system.
-@item
-The compiler used to compile Bash.
-@item
-A description of the bug behaviour.
-@item
-A short script or `recipe' which exercises the bug and may be used
-to reproduce it.
-@end itemize
-
-@noindent
-@code{bashbug} inserts the first three items automatically into
-the template it provides for filing a bug report.
-
-Please send all reports concerning this manual to
-@email{chet@@po.CWRU.Edu}.
-
-@node Major Differences From The Bourne Shell
-@appendix Major Differences From The Bourne Shell
-
-Bash implements essentially the same grammar, parameter and
-variable expansion, redirection, and quoting as the Bourne Shell. 
-Bash uses the @sc{posix} 1003.2 standard as the specification of
-how these features are to be implemented.  There are some
-differences between the traditional Bourne shell and Bash; this
-section quickly details the differences of significance.  A
-number of these differences are explained in greater depth in
-previous sections.
-This section uses the version of @code{sh} included in SVR4.2 as
-the baseline reference.
-
-@itemize @bullet
-
-@item
-Bash is @sc{posix}-conformant, even where the @sc{posix} specification
-differs from traditional @code{sh} behavior (@pxref{Bash POSIX Mode}).
-
-@item
-Bash has multi-character invocation options (@pxref{Invoking Bash}).
-
-@item
-Bash has command-line editing (@pxref{Command Line Editing}) and
-the @code{bind} builtin.
-
-@item
-Bash provides a programmable word completion mechanism
-(@pxref{Programmable Completion}), and two builtin commands,
-@code{complete} and @code{compgen}, to manipulate it.
-
-@item
-Bash has command history (@pxref{Bash History Facilities}) and the
-@code{history} and @code{fc} builtins to manipulate it.
-The Bash history list maintains timestamp information and uses the
-value of the @code{HISTTIMEFORMAT} variable to display it.
-
-@item
-Bash implements @code{csh}-like history expansion
-(@pxref{History Interaction}).
-
-@item
-Bash has one-dimensional array variables (@pxref{Arrays}), and the
-appropriate variable expansions and assignment syntax to use them.
-Several of the Bash builtins take options to act on arrays.
-Bash provides a number of built-in array variables.
-
-@item
-The @code{$'@dots{}'} quoting syntax, which expands ANSI-C
-backslash-escaped characters in the text between the single quotes,
-is supported (@pxref{ANSI-C Quoting}).
-
-@item
-Bash supports the @code{$"@dots{}"} quoting syntax to do
-locale-specific translation of the characters between the double
-quotes.  The @option{-D}, @option{--dump-strings}, and @option{--dump-po-strings}
-invocation options list the translatable strings found in a script
-(@pxref{Locale Translation}).
-
-@item
-Bash implements the @code{!} keyword to negate the return value of
-a pipeline (@pxref{Pipelines}).
-Very useful when an @code{if} statement needs to act only if a test fails.
-
-@item
-Bash has the @code{time} reserved word and command timing (@pxref{Pipelines}).
-The display of the timing statistics may be controlled with the
-@env{TIMEFORMAT} variable.
-
-@item
-Bash implements the @code{for (( @var{expr1} ; @var{expr2} ; @var{expr3} ))}
-arithmetic for command, similar to the C language (@pxref{Looping Constructs}).
-
-@item
-Bash includes the @code{select} compound command, which allows the
-generation of simple menus (@pxref{Conditional Constructs}).
-
-@item
-Bash includes the @code{[[} compound command, which makes conditional
-testing part of the shell grammar (@pxref{Conditional Constructs}).
-
-@item
-Bash includes brace expansion (@pxref{Brace Expansion}) and tilde
-expansion (@pxref{Tilde Expansion}).
-
-@item
-Bash implements command aliases and the @code{alias} and @code{unalias}
-builtins (@pxref{Aliases}).
-
-@item
-Bash provides shell arithmetic, the @code{((} compound command
-(@pxref{Conditional Constructs}),
-and arithmetic expansion (@pxref{Shell Arithmetic}).
-
-@item
-Variables present in the shell's initial environment are automatically
-exported to child processes.  The Bourne shell does not normally do
-this unless the variables are explicitly marked using the @code{export}
-command.
-
-@item
-Bash includes the @sc{posix} pattern removal @samp{%}, @samp{#}, @samp{%%}
-and @samp{##} expansions to remove leading or trailing substrings from
-variable values (@pxref{Shell Parameter Expansion}).
-
-@item
-The expansion @code{$@{#xx@}}, which returns the length of @code{$@{xx@}},
-is supported (@pxref{Shell Parameter Expansion}).
-
-@item
-The expansion @code{$@{var:}@var{offset}@code{[:}@var{length}@code{]@}},
-which expands to the substring of @code{var}'s value of length
-@var{length}, beginning at @var{offset}, is present
-(@pxref{Shell Parameter Expansion}).
-
-@item
-The expansion
-@code{$@{var/[/]}@var{pattern}@code{[/}@var{replacement}@code{]@}},
-which matches @var{pattern} and replaces it with @var{replacement} in
-the value of @code{var}, is available (@pxref{Shell Parameter Expansion}).
-
-@item
-The expansion @code{$@{!@var{prefix@}*}} expansion, which expands to
-the names of all shell variables whose names begin with @var{prefix},
-is available (@pxref{Shell Parameter Expansion}).
-
-@item
-Bash has @var{indirect} variable expansion using @code{$@{!word@}}
-(@pxref{Shell Parameter Expansion}).
-
-@item
-Bash can expand positional parameters beyond @code{$9} using
-@code{$@{@var{num}@}}.
-
-@item
-The @sc{posix} @code{$()} form of command substitution
-is implemented (@pxref{Command Substitution}),
-and preferred to the Bourne shell's @code{``} (which
-is also implemented for backwards compatibility).
-
-@item
-Bash has process substitution (@pxref{Process Substitution}).
-
-@item
-Bash automatically assigns variables that provide information about the
-current user (@env{UID}, @env{EUID}, and @env{GROUPS}), the current host
-(@env{HOSTTYPE}, @env{OSTYPE}, @env{MACHTYPE}, and @env{HOSTNAME}),
-and the instance of Bash that is running (@env{BASH},
-@env{BASH_VERSION}, and @env{BASH_VERSINFO}).  @xref{Bash Variables},
-for details.
-
-@item
-The @env{IFS} variable is used to split only the results of expansion,
-not all words (@pxref{Word Splitting}).
-This closes a longstanding shell security hole.
-
-@item
-Bash implements the full set of @sc{posix} 1003.2 filename expansion operators,
-including @var{character classes}, @var{equivalence classes}, and
-@var{collating symbols} (@pxref{Filename Expansion}).
-
-@item
-Bash implements extended pattern matching features when the @code{extglob}
-shell option is enabled (@pxref{Pattern Matching}).
-
-@item
-It is possible to have a variable and a function with the same name;
-@code{sh} does not separate the two name spaces.
-
-@item
-Bash functions are permitted to have local variables using the
-@code{local} builtin, and thus useful recursive functions may be written
-(@pxref{Bash Builtins}).
-
-@item
-Variable assignments preceding commands affect only that command, even
-builtins and functions (@pxref{Environment}).
-In @code{sh}, all variable assignments 
-preceding commands are global unless the command is executed from the
-file system.
-
-@item
-Bash performs filename expansion on filenames specified as operands
-to input and output redirection operators (@pxref{Redirections}).
-
-@item
-Bash contains the @samp{<>} redirection operator, allowing a file to be
-opened for both reading and writing, and the @samp{&>} redirection
-operator, for directing standard output and standard error to the same
-file (@pxref{Redirections}).
-
-@item
-Bash treats a number of filenames specially when they are
-used in redirection operators (@pxref{Redirections}).
-
-@item
-Bash can open network connections to arbitrary machines and services
-with the redirection operators (@pxref{Redirections}).
-
-@item
-The @code{noclobber} option is available to avoid overwriting existing
-files with output redirection (@pxref{The Set Builtin}).
-The @samp{>|} redirection operator may be used to override @code{noclobber}.
-
-@item
-The Bash @code{cd} and @code{pwd} builtins (@pxref{Bourne Shell Builtins})
-each take @option{-L} and @option{-P} options to switch between logical and
-physical modes.
-
-@item
-Bash allows a function to override a builtin with the same name, and provides
-access to that builtin's functionality within the function via the
-@code{builtin} and @code{command} builtins (@pxref{Bash Builtins}).
-
-@item
-The @code{command} builtin allows selective disabling of functions
-when command lookup is performed (@pxref{Bash Builtins}).
-
-@item
-Individual builtins may be enabled or disabled using the @code{enable}
-builtin (@pxref{Bash Builtins}).
-
-@item
-The Bash @code{exec} builtin takes additional options that allow users
-to control the contents of the environment passed to the executed
-command, and what the zeroth argument to the command is to be
-(@pxref{Bourne Shell Builtins}).
-
-@item
-Shell functions may be exported to children via the environment
-using @code{export -f} (@pxref{Shell Functions}).
-
-@item
-The Bash @code{export}, @code{readonly}, and @code{declare} builtins can
-take a @option{-f} option to act on shell functions, a @option{-p} option to
-display variables with various attributes set in a format that can be
-used as shell input, a @option{-n} option to remove various variable
-attributes, and @samp{name=value} arguments to set variable attributes
-and values simultaneously.
-
-@item
-The Bash @code{hash} builtin allows a name to be associated with
-an arbitrary filename, even when that filename cannot be found by
-searching the @env{$PATH}, using @samp{hash -p}
-(@pxref{Bourne Shell Builtins}).
-
-@item
-Bash includes a @code{help} builtin for quick reference to shell
-facilities (@pxref{Bash Builtins}).
-
-@item
-The @code{printf} builtin is available to display formatted output
-(@pxref{Bash Builtins}).
-
-@item
-The Bash @code{read} builtin (@pxref{Bash Builtins})
-will read a line ending in @samp{\} with
-the @option{-r} option, and will use the @env{REPLY} variable as a
-default if no non-option arguments are supplied.
-The Bash @code{read} builtin
-also accepts a prompt string with the @option{-p} option and will use
-Readline to obtain the line when given the @option{-e} option.
-The @code{read} builtin also has additional options to control input:
-the @option{-s} option will turn off echoing of input characters as
-they are read, the @option{-t} option will allow @code{read} to time out
-if input does not arrive within a specified number of seconds, the
-@option{-n} option will allow reading only a specified number of
-characters rather than a full line, and the @option{-d} option will read
-until a particular character rather than newline.
-
-@item
-The @code{return} builtin may be used to abort execution of scripts
-executed with the @code{.} or @code{source} builtins
-(@pxref{Bourne Shell Builtins}).
-
-@item
-Bash includes the @code{shopt} builtin, for finer control of shell
-optional capabilities (@pxref{Bash Builtins}), and allows these options
-to be set and unset at shell invocation (@pxref{Invoking Bash}).
-
-@item
-Bash has much more optional behavior controllable with the @code{set}
-builtin (@pxref{The Set Builtin}).
-
-@item
-The @samp{-x} (@code{xtrace}) option displays commands other than
-simple commands when performing an execution trace
-(@pxref{The Set Builtin}).
-
-@item
-The @code{test} builtin (@pxref{Bourne Shell Builtins})
-is slightly different, as it implements the @sc{posix} algorithm,
-which specifies the behavior based on the number of arguments.
-
-@item
-Bash includes the @code{caller} builtin, which displays the context of
-any active subroutine call (a shell function or a script executed with
-the @code{.} or @code{source} builtins).  This supports the bash
-debugger.
-
-@item
-The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows a
-@code{DEBUG} pseudo-signal specification, similar to @code{EXIT}.
-Commands specified with a @code{DEBUG} trap are executed before every
-simple command, @code{for} command, @code{case} command,
-@code{select} command, every arithmetic @code{for} command, and before
-the first command executes in a shell function.
-The @code{DEBUG} trap is not inherited by shell functions unless the
-function has been given the @code{trace} attribute or the
-@code{functrace} option has been enabled using the @code{shopt} builtin.
-The @code{extdebug} shell option has additional effects on the
-@code{DEBUG} trap.
-
-The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows an
-@code{ERR} pseudo-signal specification, similar to @code{EXIT} and @code{DEBUG}.
-Commands specified with an @code{ERR} trap are executed after a simple
-command fails, with a few exceptions.
-The @code{ERR} trap is not inherited by shell functions unless the
-@code{-o errtrace} option to the @code{set} builtin is enabled.
-
-The @code{trap} builtin (@pxref{Bourne Shell Builtins}) allows a
-@code{RETURN} pseudo-signal specification, similar to
-@code{EXIT} and @code{DEBUG}.
-Commands specified with an @code{RETURN} trap are executed before
-execution resumes after a shell function or a shell script executed with
-@code{.} or @code{source} returns.
-The @code{RETURN} trap is not inherited by shell functions.
-
-@item
-The Bash @code{type} builtin is more extensive and gives more information
-about the names it finds (@pxref{Bash Builtins}).
-
-@item
-The Bash @code{umask} builtin permits a @option{-p} option to cause
-the output to be displayed in the form of a @code{umask} command
-that may be reused as input (@pxref{Bourne Shell Builtins}).
-
-@item
-Bash implements a @code{csh}-like directory stack, and provides the
-@code{pushd}, @code{popd}, and @code{dirs} builtins to manipulate it
-(@pxref{The Directory Stack}).
-Bash also makes the directory stack visible as the value of the
-@env{DIRSTACK} shell variable.
-
-@item
-Bash interprets special backslash-escaped characters in the prompt
-strings when interactive (@pxref{Printing a Prompt}).
-
-@item
-The Bash restricted mode is more useful (@pxref{The Restricted Shell});
-the SVR4.2 shell restricted mode is too limited.
-
-@item
-The @code{disown} builtin can remove a job from the internal shell
-job table (@pxref{Job Control Builtins}) or suppress the sending
-of @code{SIGHUP} to a job when the shell exits as the result of a
-@code{SIGHUP}.
-
-@item
-The SVR4.2 shell has two privilege-related builtins
-(@code{mldmode} and @code{priv}) not present in Bash.
-
-@item
-Bash does not have the @code{stop} or @code{newgrp} builtins.
-
-@item
-Bash does not use the @env{SHACCT} variable or perform shell accounting.
-
-@item
-The SVR4.2 @code{sh} uses a @env{TIMEOUT} variable like Bash uses
-@env{TMOUT}.
-
-@end itemize
-
-@noindent
-More features unique to Bash may be found in @ref{Bash Features}.
-
-
-@appendixsec Implementation Differences From The SVR4.2 Shell
-
-Since Bash is a completely new implementation, it does not suffer from
-many of the limitations of the SVR4.2 shell.  For instance:
-
-@itemize @bullet
-
-@item
-Bash does not fork a subshell when redirecting into or out of
-a shell control structure such as  an @code{if} or @code{while}
-statement.
-
-@item
-Bash does not allow unbalanced quotes.  The SVR4.2 shell will silently
-insert a needed closing quote at @code{EOF} under certain circumstances.
-This can be the cause of some hard-to-find errors.
-
-@item
-The SVR4.2 shell uses a baroque memory management scheme based on
-trapping @code{SIGSEGV}.  If the shell is started from a process with
-@code{SIGSEGV} blocked (e.g., by using the @code{system()} C library
-function call), it misbehaves badly.
-
-@item
-In a questionable attempt at security, the SVR4.2 shell,
-when invoked without the @option{-p} option, will alter its real
-and effective @sc{uid} and @sc{gid} if they are less than some
-magic threshold value, commonly 100.
-This can lead to unexpected results.
-
-@item
-The SVR4.2 shell does not allow users to trap @code{SIGSEGV},
-@code{SIGALRM}, or @code{SIGCHLD}.
-
-@item
-The SVR4.2 shell does not allow the @env{IFS}, @env{MAILCHECK},
-@env{PATH}, @env{PS1}, or @env{PS2} variables to be unset.
-
-@item
-The SVR4.2 shell treats @samp{^} as the undocumented equivalent of
-@samp{|}.
-
-@item
-Bash allows multiple option arguments when it is invoked (@code{-x -v});
-the SVR4.2 shell allows only one option argument (@code{-xv}).  In
-fact, some versions of the shell dump core if the second argument begins
-with a @samp{-}.
-
-@item
-The SVR4.2 shell exits a script if any builtin fails; Bash exits
-a script only if one of the @sc{posix} 1003.2 special builtins fails, and
-only for certain failures, as enumerated in the @sc{posix} 1003.2 standard.
-
-@item 
-The SVR4.2 shell behaves differently when invoked as @code{jsh}
-(it turns on job control).
-@end itemize
-
-@node Copying This Manual
-@appendix Copying This Manual
-
-@menu
-* GNU Free Documentation License::      License for copying this manual.
-@end menu
-
-@include fdl.texi
-
-@node Builtin Index
-@unnumbered Index of Shell Builtin Commands
-@printindex bt
-
-@node Reserved Word Index
-@unnumbered Index of Shell Reserved Words
-@printindex rw
-
-@node Variable Index
-@unnumbered Parameter and Variable Index
-@printindex vr
-
-@node Function Index
-@unnumbered Function Index
-@printindex fn
-
-@node Concept Index
-@unnumbered Concept Index
-@printindex cp
-
-@bye