+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} 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{$PATH} to find the new location. This is also available with
+@samp{shopt -s checkhash}.
+
+@item
+The message printed by the job control code and builtins when a job
+exits with a non-zero status is `Done(status)'.
+
+@item
+The message printed by the job control code and builtins when a job
+is stopped is `Stopped(@var{signame})', where @var{signame} is, for
+example, @code{SIGTSTP}.
+
+@item
+The @code{bg} builtin uses the required format to describe each job placed
+in the background, which does not include an indication of whether the job
+is the current or previous job.
+
+@item
+Reserved words appearing in a context where reserved words are recognized
+do not undergo alias expansion.
+
+@item
+The @sc{posix} @env{PS1} and @env{PS2} expansions of @samp{!} to
+the history number and @samp{!!} to @samp{!} are enabled,
+and parameter expansion is performed on the values of @env{PS1} and
+@env{PS2} regardless of the setting of the @code{promptvars} option.
+
+@item
+The @sc{posix} startup files are executed (@env{$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{$HISTFILE}).
+
+@item
+The output of @samp{kill -l} prints all the signal names on a single line,
+separated by spaces, without the @samp{SIG} prefix.
+
+@item
+The @code{kill} builtin does not accept signal names with a @samp{SIG}
+prefix.
+
+@item
+Non-interactive shells exit if @var{filename} in @code{.} @var{filename}
+is not found.
+
+@item
+Non-interactive shells exit if a syntax error in an arithmetic expansion
+results in an invalid expression.
+
+@item
+Redirection operators do not perform filename expansion on the word
+in the redirection unless the shell is interactive.
+
+@item
+Redirection operators do not perform word splitting on the word in the
+redirection.
+
+@item
+Function names must be valid shell @code{name}s. That is, they may not
+contain characters other than letters, digits, and underscores, and
+may not start with a digit. Declaring a function with an invalid name
+causes a fatal syntax error in non-interactive shells.
+
+@item
+@sc{posix} special builtins are found before shell functions
+during command lookup.
+
+@item
+If a @sc{posix} special builtin returns an error status, a
+non-interactive shell exits. The fatal errors are those listed in
+the POSIX standard, and include things like passing incorrect options,
+redirection errors, variable assignment errors for assignments preceding
+the command name, and so on.
+
+@item
+If @env{CDPATH} is set, the @code{cd} builtin will not implicitly
+append the current directory to it. This means that @code{cd} will
+fail if no valid directory name can be constructed from
+any of the entries in @env{$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} 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}.
+
+@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, unless that argument consists solely of digits and
+is a valid signal number. 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{$PWD} and the directory name supplied as an argument
+does not refer to an existing directory, @code{cd} will fail instead of
+falling back to @var{physical} mode.
+
+@item
+When the @code{pwd} builtin is supplied the @option{-P} option, it resets
+@code{$PWD} to a pathname containing no symlinks.
+
+@item
+The @code{pwd} builtin verifies that the value it prints is the same as the
+current directory, even if it is not asked to check the file system with the
+@option{-P} option.
+
+@item
+When listing the history, the @code{fc} builtin does not include an
+indication of whether or not a history entry has been modified.
+
+@item
+The default editor used by @code{fc} is @code{ed}.
+
+@item
+The @code{type} and @code{command} builtins will not report a non-executable
+file as having been found, though the shell will attempt to execute such a
+file if it is the only so-named file found in @code{$PATH}.
+
+@item
+The @code{vi} editing mode will invoke the @code{vi} editor directly when
+the @samp{v} command is run, instead of checking @code{$VISUAL} and
+@code{$EDITOR}.
+
+@item
+When the @code{xpg_echo} option is enabled, Bash does not attempt to interpret
+any arguments to @code{echo} as options. Each argument is displayed, after
+escape characters are converted.
+
+@item
+The @code{ulimit} builtin uses a block size of 512 bytes for the @option{-c}
+and @option{-f} options.
+
+@end enumerate
+
+There is other @sc{posix} behavior that Bash does not implement by
+default even when in @sc{posix} mode.
+Specifically:
+
+@enumerate
+
+@item
+The @code{fc} builtin checks @code{$EDITOR} as a program to edit history
+entries if @code{FCEDIT} is unset, rather than defaulting directly to
+@code{ed}. @code{fc} uses @code{ed} if @code{EDITOR} is unset.
+
+@item
+As noted above, Bash requires the @code{xpg_echo} option to be enabled for
+the @code{echo} builtin to be fully conformant.
+
+@end enumerate
+
+Bash can be configured to be @sc{posix}-conformant by default, by specifying
+the @option{--enable-strict-posix-default} to @code{configure} when building
+(@pxref{Optional Features}).
+
+@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 specification (@var{jobspec}).
+
+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.
+A single @samp{%} (with no accompanying job specification) also refers
+to the current job.
+The previous job may be referenced using @samp{%-}.
+If there is only a single job, @samp{%+} and @samp{%-} can both be used
+to refer to that job.
+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, (or running, if
+the @code{checkjobs} option is enabled -- see @ref{The Shopt Builtin}), the
+shell prints a warning message, and if the @code{checkjobs} option is
+enabled, lists the jobs and their statuses.
+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 any stopped jobs are terminated.
+
+@node Job Control Builtins
+@section Job Control Builtins
+
+@table @code
+
+@item bg
+@btindex bg
+@example
+bg [@var{jobspec} @dots{}]
+@end example
+Resume each 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, any
+@var{jobspec} was not found or 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 each 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.
+A login shell cannot be suspended; the @option{-f}
+option can be used to override this and force the suspension.
+
+@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.