.\" MAN PAGE COMMENTS to
.\"
.\" Chet Ramey
-.\" Information Network Services
.\" Case Western Reserve University
-.\" chet@ins.CWRU.Edu
+.\" chet@po.cwru.edu
.\"
-.\" Last Change: Wed Apr 1 12:16:09 EST 1998
+.\" Last Change: Mon Dec 29 16:49:01 EST 2008
.\"
.\" bash_builtins, strip all but Built-Ins section
.if \n(zZ=1 .ig zZ
-.TH BASH 1 "1998 Apr 1" GNU
+.if \n(zY=1 .ig zY
+.TH BASH 1 "2008 December 29" "GNU Bash-4.0"
.\"
.\" There's some problem with having a `@'
.\" in a tagged paragraph with the BSD man macros.
[options]
[file]
.SH COPYRIGHT
-.if n Bash is Copyright (C) 1989, 1991, 1993, 1995, 1996 by the Free Software Foundation, Inc.
-.if t Bash is Copyright \(co 1989, 1991, 1993, 1995, 1996 by the Free Software Foundation, Inc.
+.if n Bash is Copyright (C) 1989-2009 by the Free Software Foundation, Inc.
+.if t Bash is Copyright \(co 1989-2009 by the Free Software Foundation, Inc.
.SH DESCRIPTION
.B Bash
is an \fBsh\fR-compatible command language interpreter that
shells (\fBksh\fP and \fBcsh\fP).
.PP
.B Bash
-is intended to be a conformant implementation of the IEEE
-POSIX Shell and Tools specification (IEEE Working Group 1003\.2).
+is intended to be a conformant implementation of the
+Shell and Utilities portion of the IEEE POSIX specification
+(IEEE Standard 1003.1).
+.B Bash
+can be configured to be POSIX-conformant by default.
.SH OPTIONS
In addition to the single-character shell options documented in the
description of the \fBset\fR builtin command, \fBbash\fR
they are assigned to the positional parameters, starting with
.BR $0 .
.TP
+.B \-i
+If the
+.B \-i
+option is present, the shell is
+.IR interactive .
+.TP
+.B \-l
+Make
+.B bash
+act as if it had been invoked as a login shell (see
+.SM
+.B INVOCATION
+below).
+.TP
.B \-r
If the
.B \-r
.B "RESTRICTED SHELL"
below).
.TP
-.B \-i
-If the
-.B \-i
-option is present, the shell is
-.IR interactive .
-.TP
.B \-s
If the
.B \-s
.TP
.B \-D
A list of all double-quoted strings preceded by \fB$\fP
-is printed on the standard ouput.
+is printed on the standard output.
These are the strings that
are subject to language translation when the current locale
-is not C or POSIX.
+is not \fBC\fP or \fBPOSIX\fP.
This implies the \fB\-n\fP option; no commands will be executed.
.TP
+.B [\-+]O [\fIshopt_option\fP]
+\fIshopt_option\fP is one of the shell options accepted by the
+\fBshopt\fP builtin (see
+.SM
+.B SHELL BUILTIN COMMANDS
+below).
+If \fIshopt_option\fP is present, \fB\-O\fP sets the value of that option;
+\fB+O\fP unsets it.
+If \fIshopt_option\fP is not supplied, the names and values of the shell
+options accepted by \fBshopt\fP are printed on the standard output.
+If the invocation option is \fB+O\fP, the output is displayed in a format
+that may be reused as input.
+.TP
.B \-\-
A
.B \-\-
.B Bash
also interprets a number of multi-character options.
These options must appear on the command line before the
-single-character options in order for them to be recognized.
+single-character options to be recognized.
.PP
.PD 0
.TP
+.B \-\-debugger
+Arrange for the debugger profile to be executed before the shell
+starts.
+Turns on extended debugging mode (see the description of the
+.B extdebug
+option to the
+.B shopt
+builtin below)
+and shell function tracing (see the description of the
+\fB\-o functrace\fP option to the
+.B set
+builtin below).
+.TP
.B \-\-dump\-po\-strings
Equivalent to \fB\-D\fP, but the output is in the GNU \fIgettext\fP
\fBpo\fP (portable object) file format.
.B \-\-help
Display a usage message on standard output and exit successfully.
.TP
-.B \-\-login
-Make
-.B bash
-act as if it had been invoked as a login shell (see
+\fB\-\-init\-file\fP \fIfile\fP
+.PD 0
+.TP
+\fB\-\-rcfile\fP \fIfile\fP
+.PD
+Execute commands from
+.I file
+instead of the standard personal initialization file
+.I ~/.bashrc
+if the shell is interactive (see
.SM
.B INVOCATION
below).
.TP
+.B \-\-login
+Equivalent to \fB\-l\fP.
+.TP
.B \-\-noediting
Do not use the GNU
.B readline
-library to read command lines if interactive.
+library to read command lines when the shell is interactive.
.TP
.B \-\-noprofile
Do not read either the system-wide startup file
.TP
.B \-\-posix
Change the behavior of \fBbash\fP where the default operation differs
-from the POSIX 1003.2 standard to match the standard.
-.TP
-\fB\-\-rcfile\fP \fIfile\fP
-Execute commands from
-.I file
-instead of the standard personal initialization file
-.I ~/.bashrc
-if the shell is interactive (see
-.SM
-.B INVOCATION
-below).
+from the POSIX standard to match the standard (\fIposix mode\fP).
.TP
.B \-\-restricted
The shell becomes restricted (see
\fBBash\fP'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.
+An attempt is first made to open the file in the current directory, and,
+if no file is found, then the shell searches the directories in
+.SM
+.B PATH
+for the script.
.SH INVOCATION
A \fIlogin shell\fP is one whose first character of argument zero is a
.BR \- ,
.B \-\-login
option.
.PP
-An \fIinteractive\fP shell is one whose standard input and output are
+An \fIinteractive\fP shell is one started without non-option arguments
+and without the
+.B \-c
+option
+whose standard input and error are
both connected to terminals (as determined by
.IR isatty (3)),
or one started with the
.PP
When
.B bash
-is invoked as an interactive login shell, it first reads and
+is invoked as an interactive login shell, or as a non-interactive shell
+with the \fB\-\-login\fP option, it first reads and
executes commands from the file \fI/etc/profile\fP, if that
file exists.
After reading that file, it looks for \fI~/.bash_profile\fP,
behaves as if the following command were executed:
.sp .5
.RS
-\f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP
+.if t \f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP
+.if n if [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
.RE
.sp .5
but the value of the
.B sh
as closely as possible,
while conforming to the POSIX standard as well.
-When invoked as an interactive login shell, it first attempts to
+When invoked as an interactive login shell, or a non-interactive
+shell with the \fB\-\-login\fP option, it first attempts to
read and execute commands from
.I /etc/profile
and
option has no effect.
A non-interactive shell invoked with the name
.B sh
-does not attempt to read any startup files.
+does not attempt to read any other startup files.
When invoked as
.BR sh ,
.B bash
No other startup files are read.
.PP
.B Bash
-attempts to determine when it is being run by the remote shell
-daemon, usually \fIrshd\fP.
+attempts to determine when it is being run with its standard input
+connected to a a network connection, as if by the remote shell
+daemon, usually \fIrshd\fP, or the secure shell daemon \fIsshd\fP.
If
.B bash
-determines it is being run by \fIrshd\fP, it reads and executes
+determines it is being run in this fashion, it reads and executes
commands from \fI~/.bashrc\fP, if that file exists and is readable.
It will not do this if invoked as \fBsh\fP.
The
option may be used to force another file to be read, but
\fIrshd\fP does not generally invoke the shell with those options
or allow them to be specified.
+.PP
+If the shell is started with the effective user (group) id not equal to the
+real user (group) id, and the \fB\-p\fP option is not supplied, no startup
+files are read, shell functions are not inherited from the environment, the
+.SM
+.B SHELLOPTS
+variable, if it appears in the environment, is ignored,
+and the effective user id is set to the real user id.
+If the \fB\-p\fP option is supplied at invocation, the startup behavior is
+the same, but the effective user id is not reset.
.SH DEFINITIONS
.PP
The following definitions are used throughout the rest of this
symbols:
.RS
.PP
-.if t \fB\(bv\(bv & && ; ;; ( ) | <newline>\fP
-.if n \fB|| & && ; ;; ( ) | <newline>\fP
+.if t \fB\(bv\(bv & && ; ;; ( ) | |& <newline>\fP
+.if n \fB|| & && ; ;; ( ) | |& <newline>\fP
.RE
.PD
.SH "RESERVED WORDS"
.if n ! case do done elif else esac fi for function if in select then until while { } time [[ ]]
.if t ! case do done elif else esac fi for function if in select then until while { } time [[ ]]
.if t .RE
-.RE
.SH "SHELL GRAMMAR"
.SS Simple Commands
.PP
A \fIsimple command\fP is a sequence of optional variable assignments
followed by \fBblank\fP-separated words and redirections, and
terminated by a \fIcontrol operator\fP. The first word
-specifies the command to be executed. The remaining words are
-passed as arguments to the invoked command.
+specifies the command to be executed, and is passed as argument zero.
+The remaining words are passed as arguments to the invoked command.
.PP
The return value of a \fIsimple command\fP is its exit status, or
128+\fIn\^\fP if the command is terminated by signal
.SS Pipelines
.PP
A \fIpipeline\fP is a sequence of one or more commands separated by
-the character
-.BR | .
+one of the control operators
+.B |
+or \fB|&\fP.
The format for a pipeline is:
.RS
.PP
-[\fBtime\fP [\fB\-p\fP]] [ ! ] \fIcommand\fP [ \fB|\fP \fIcommand2\fP ... ]
+[\fBtime\fP [\fB\-p\fP]] [ ! ] \fIcommand\fP [ [\fB|\fP\(bv\fB|&\fP] \fIcommand2\fP ... ]
.RE
.PP
The standard output of
.I command
-is connected to the standard input of
+is connected via a pipe to the standard input of
.IR command2 .
This connection is performed before any redirections specified by the
command (see
.SM
.B REDIRECTION
below).
-.PP
+If \fB|&\fP is used, the standard error of \fIcommand\fP is connected to
+\fIcommand2\fP's standard input through the pipe; it is shorthand for
+\fB2>&1 |\fP.
+This implicit redirection of the standard error is performed after any
+redirections specified by the command.
+.PP
+The return status of a pipeline is the exit status of the last
+command, unless the \fBpipefail\fP option is enabled.
+If \fBpipefail\fP 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
.B !
-precedes a pipeline, the exit status of that
-pipeline is the logical NOT of the exit status of the last command.
-Otherwise, the status of the pipeline is the exit status of the last
-command.
+precedes a pipeline, the exit status of that pipeline is the logical
+negation of the exit status as described above.
The shell waits for all commands in the pipeline to
terminate before returning a value.
.PP
have equal precedence, followed by
.B ;
and
-.BR &,
+.BR & ,
which have equal precedence.
.PP
+A sequence of one or more newlines may appear in a \fIlist\fP instead
+of a semicolon to delimit commands.
+.PP
If a command is terminated by the control operator
.BR & ,
the shell executes the command in the \fIbackground\fP
command to terminate in turn. The return status is the
exit status of the last command executed.
.PP
-The control operators
-.B &&
-and
-.B \(bv\(bv
-denote AND lists and OR lists, respectively.
+AND and OR lists are sequences of one of more pipelines separated by the
+\fB&&\fP and \fB\(bv\(bv\fP control operators, respectively.
+AND and OR lists are executed with left associativity.
An AND list has the form
.RS
.PP
-\fIcommand\fP \fB&&\fP \fIcommand2\fP
+\fIcommand1\fP \fB&&\fP \fIcommand2\fP
.RE
.PP
.I command2
is executed if, and only if,
-.I command
+.I command1
returns an exit status of zero.
.PP
An OR list has the form
.RS
.PP
-\fIcommand\fP \fB\(bv\(bv\fP \fIcommand2\fP
+\fIcommand1\fP \fB\(bv\(bv\fP \fIcommand2\fP
.PP
.RE
.PP
.I command2
is executed if and only if
-.I command
-returns a non-zero exit status. The return status of
+.I command1
+returns a non-zero exit status.
+The return status of
AND and OR lists is the exit status of the last command
executed in the list.
.SS Compound Commands
A \fIcompound command\fP is one of the following:
.TP
(\fIlist\fP)
-\fIlist\fP is executed in a subshell. Variable assignments and builtin
+\fIlist\fP is executed in a subshell environment (see
+.SM
+\fBCOMMAND EXECUTION ENVIRONMENT\fP
+below).
+Variable assignments and builtin
commands that affect the shell's environment do not remain in effect
after the command completes. The return status is the exit status of
\fIlist\fP.
This is known as a \fIgroup command\fP.
The return status is the exit status of
\fIlist\fP.
+Note that unlike the metacharacters \fB(\fP and \fB)\fP, \fB{\fP and
+\fB}\fP are \fIreserved words\fP and must occur where a reserved
+word is permitted to be recognized. Since they do not cause a word
+break, they must be separated from \fIlist\fP by whitespace or another
+shell metacharacter.
.TP
((\fIexpression\fP))
The \fIexpression\fP is evaluated according to the rules described
between the \fB[[\fP and \fB]]\fP; tilde expansion, parameter and
variable expansion, arithmetic expansion, command substitution, process
substitution, and quote removal are performed.
+Conditional operators such as \fB\-f\fP must be unquoted to be recognized
+as primaries.
.if t .sp 0.5
.if n .sp 1
When the \fB==\fP and \fB!=\fP operators are used, the string to the
right of the operator is considered a pattern and matched according
to the rules described below under \fBPattern Matching\fP.
-The return value is 0 if the string matches or does not match
-the pattern, respectively, and 1 otherwise.
+If the shell option
+.B nocasematch
+is enabled, the match is performed without regard to the case
+of alphabetic characters.
+The return value is 0 if the string matches (\fB==\fP) or does not match
+(\fB!=\fP) the pattern, and 1 otherwise.
+Any part of the pattern may be quoted to force it to be matched as a
+string.
+.if t .sp 0.5
+.if n .sp 1
+An additional binary operator, \fB=~\fP, is available, with the same
+precedence as \fB==\fP and \fB!=\fP.
+When it is used, the string to the right of the operator is considered
+an extended regular expression and matched accordingly (as in \fIregex\fP(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
+.B nocasematch
+is enabled, the match is performed without regard to the case
+of alphabetic characters.
Any part of the pattern may be quoted to force it to be matched as a
string.
+Substrings matched by parenthesized subexpressions within the regular
+expression are saved in the array variable \fBBASH_REMATCH\fP.
+The element of \fBBASH_REMATCH\fP with index 0 is the portion of the string
+matching the entire regular expression.
+The element of \fBBASH_REMATCH\fP with index \fIn\fP is the portion of the
+string matching the \fIn\fPth parenthesized subexpression.
.if t .sp 0.5
.if n .sp 1
Expressions may be combined using the following operators, listed
.I expression2
is true.
.PD
-.RE
.LP
The \fB&&\fP and
.if t \fB\(bv\(bv\fP
.if n \fB||\fP
-operators do not execute \fIexpression2\fP if the value of
+operators do not evaluate \fIexpression2\fP if the value of
\fIexpression1\fP is sufficient to determine the return value of
the entire conditional expression.
+.RE
.TP
-\fBfor\fP \fIname\fP [ \fBin\fP \fIword\fP; ] \fBdo\fP \fIlist\fP ; \fBdone\fP
+\fBfor\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP
The list of words following \fBin\fP is expanded, generating a list
-of items. The variable \fIname\fP is set to each element of this list
-in turn, and \fIlist\fP is executed each time. If the \fBin\fP
-\fIword\fP is omitted, the \fBfor\fP command executes \fIlist\fP
-once for each positional parameter that is set (see
+of items.
+The variable \fIname\fP is set to each element of this list
+in turn, and \fIlist\fP is executed each time.
+If the \fBin\fP \fIword\fP is omitted, the \fBfor\fP command executes
+\fIlist\fP once for each positional parameter that is set (see
.SM
.B PARAMETERS
below).
If the expansion of the items following \fBin\fP results in an empty
list, no commands are executed, and the return status is 0.
.TP
-\fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP; ] \fBdo\fP \fIlist\fP ; \fBdone\fP
+\fBfor\fP (( \fIexpr1\fP ; \fIexpr2\fP ; \fIexpr3\fP )) ; \fBdo\fP \fIlist\fP ; \fBdone\fP
+First, the arithmetic expression \fIexpr1\fP is evaluated according
+to the rules described below under
+.SM
+.BR "ARITHMETIC EVALUATION" .
+The arithmetic expression \fIexpr2\fP is then evaluated repeatedly
+until it evaluates to zero.
+Each time \fIexpr2\fP evaluates to a non-zero value, \fIlist\fP is
+executed and the arithmetic expression \fIexpr3\fP 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 \fIlist\fP
+that is executed, or false if any of the expressions is invalid.
+.TP
+\fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP
The list of words following \fBin\fP is expanded, generating a list
of items. The set of expanded words is printed on the standard
error, each preceded by a number. If the \fBin\fP
.I list
is executed after each selection until a
.B break
-or
-.B return
command is executed.
The exit status of
.B select
.IR list ,
or zero if no commands were executed.
.TP
-\fBcase\fP \fIword\fP \fBin\fP [ ( \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \
+\fBcase\fP \fIword\fP \fBin\fP [ [(] \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \
... ) \fIlist\fP ;; ] ... \fBesac\fP
A \fBcase\fP command first expands \fIword\fP, and tries to match
it against each \fIpattern\fP in turn, using the same matching rules
as for pathname expansion (see
.B Pathname Expansion
-below). When a match is found, the
-corresponding \fIlist\fP is executed. After the first match, no
-subsequent matches are attempted. The exit status is zero if no
+below).
+The \fIword\fP is expanded using tilde
+expansion, parameter and variable expansion, arithmetic substitution,
+command substitution, process substitution and quote removal.
+Each \fIpattern\fP examined is expanded using tilde
+expansion, parameter and variable expansion, arithmetic substitution,
+command substitution, and process substitution.
+If the shell option
+.B nocasematch
+is enabled, the match is performed without regard to the case
+of alphabetic characters.
+When a match is found, the corresponding \fIlist\fP is executed.
+If the \fB;;\fP operator is used, no subsequent matches are attempted after
+the first pattern match.
+Using \fB;&\fP in place of \fB;;\fP causes execution to continue with
+the \fIlist\fP associated with the next set of patterns.
+Using \fB;;&\fP in place of \fB;;\fP causes the shell to test the next
+pattern list in the statement, if any, and execute any associated \fIlist\fP
+on a successful match.
+The exit status is zero if no
pattern matches. Otherwise, it is the exit status of the
last command executed in \fIlist\fP.
.TP
executed, if present. The exit status is the exit status of the
last command executed, or zero if no condition tested true.
.TP
-.PD 0
\fBwhile\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP
+.PD 0
.TP
\fBuntil\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP
.PD
is the exit status
of the last \fBdo\fP \fIlist\fP command executed, or zero if
none was executed.
-.TP
-[ \fBfunction\fP ] \fIname\fP () { \fIlist\fP; }
-This defines a function named \fIname\fP. The \fIbody\fP of the
-function is the
-.I list
-of commands between { and }. This list
-is executed whenever \fIname\fP is specified as the
-name of a simple command. The exit status of a function is
-the exit status of the last command executed in the body. (See
+.SS Coprocesses
+.PP
+A \fIcoprocess\fP is a shell command preceded by the \fBcoproc\fP reserved
+word.
+A coprocess is executed asynchronously in a subshell, as if the command
+had been terminated with the \fB&\fP control operator, with a two-way pipe
+established between the executing shell and the coprocess.
+.PP
+The format for a coprocess is:
+.RS
+.PP
+\fBcoproc\fP [\fINAME\fP] \fIcommand\fP [\fIredirections\fP]
+.RE
+.PP
+This creates a coprocess named \fINAME\fP.
+If \fINAME\fP is not supplied, the default name is \fICOPROC\fP.
+When the coproc is executed, the shell creates an array variable (see
+.B Arrays
+below) named \fINAME\fP in the context of the executing shell.
+The standard output of
+.I command
+is connected via a pipe to a file descriptor in the executing shell,
+and that file descriptor is assigned to \fINAME\fP[0].
+The standard input of
+.I command
+is connected via a pipe to a file descriptor in the executing shell,
+and that file descriptor is assigned to \fINAME\fP[1].
+This pipe is established before any redirections specified by the
+command (see
+.SM
+.B REDIRECTION
+below).
+The file descriptors can be utilized as arguments to shell commands
+and redirections using standard word expansions.
+The process id of the shell spawned to execute the coprocess is
+available as the value of the variable \fINAME\fP_PID.
+The \fBwait\fP
+builtin command may be used to wait for the coprocess to terminate.
+.PP
+The return status of a coprocess is the exit status of \fIcommand\fP.
+.SS Shell Function Definitions
+.PP
+A shell function is an object that is called like a simple command and
+executes a compound command with a new set of positional parameters.
+Shell functions are declared as follows:
+.TP
+[ \fBfunction\fP ] \fIname\fP () \fIcompound\-command\fP [\fIredirection\fP]
+This defines a function named \fIname\fP.
+The reserved word \fBfunction\fP is optional.
+If the \fBfunction\fP reserved word is supplied, the parentheses are optional.
+The \fIbody\fP of the function is the compound command
+.I compound\-command
+(see \fBCompound Commands\fP above).
+That command is usually a \fIlist\fP of commands between { and }, but
+may be any command listed under \fBCompound Commands\fP above.
+\fIcompound\-command\fP is executed whenever \fIname\fP is specified as the
+name of a simple command.
+Any redirections (see
+.SM
+.B REDIRECTION
+below) specified when a function is defined are performed
+when the function is executed.
+The exit status of a function definition is zero unless a syntax error
+occurs or a readonly function with the same name already exists.
+When executed, the exit status of a function is the exit status of the
+last command executed in the body. (See
.SM
.B FUNCTIONS
below.)
Each of the \fImetacharacters\fP listed above under
.SM
.B DEFINITIONS
-has special meaning to the shell and must be quoted if they are to
-represent themselves. There are three quoting mechanisms: the
+has special meaning to the shell and must be quoted if it is to
+represent itself.
+.PP
+When the command history expansion facilities are being used
+(see
+.SM
+.B HISTORY EXPANSION
+below), the
+\fIhistory expansion\fP character, usually \fB!\fP, must be quoted
+to prevent history expansion.
+.PP
+There are three quoting mechanisms: the
.IR "escape character" ,
single quotes, and double quotes.
.PP
Enclosing characters in double quotes preserves the literal value
of all characters within the quotes, with the exception of
.BR $ ,
-.BR ` ,
-and
-.BR \e .
+.BR \` ,
+.BR \e ,
+and, when history expansion is enabled,
+.BR ! .
The characters
.B $
and
-.B `
+.B \`
retain their special meaning within double quotes. The backslash
retains its special meaning only when followed by one of the following
characters:
.BR $ ,
-.BR ` ,
+.BR \` ,
\^\fB"\fP\^,
.BR \e ,
or
.BR <newline> .
A double quote may be quoted within double quotes by preceding it with
a backslash.
+If enabled, history expansion will be performed unless an
+.B !
+appearing in double quotes is escaped using a backslash.
+The backslash preceding the
+.B !
+is not removed.
.PP
The special parameters
.B *
.B PARAMETERS
below).
.PP
-Words of the form \fB$\fP'\fIstring\fP' are treated specially. The
+Words of the form \fB$\fP\(aq\fIstring\fP\(aq are treated specially. The
word expands to \fIstring\fP, with backslash-escaped characters replaced
-as specifed by the ANSI C standard. Backslash escape sequences, if
+as specified by the ANSI C standard. Backslash escape sequences, if
present, are decoded as follows:
.RS
.PD 0
.TP
.B \e\e
backslash
+.TP
+.B \e\(aq
+single quote
.TP
.B \e\fInnn\fP
-the character whose ASCII code is the octal value \fInnn\fP
+the eight-bit character whose value is the octal value \fInnn\fP
(one to three digits)
.TP
-.B \ex\fInnn\fP
-the character whose ASCII code is the hexadecimal value \fInnn\fP
-(one to three digits)
+.B \ex\fIHH\fP
+the eight-bit character whose value is the hexadecimal value \fIHH\fP
+(one or two hex digits)
+.TP
+.B \ec\fIx\fP
+a control-\fIx\fP character
.PD
.RE
.LP
-The translated result is single-quoted, as if the dollar sign had
+The expanded result is single-quoted, as if the dollar sign had
not been present.
.PP
A double-quoted string preceded by a dollar sign (\fB$\fP) will cause
.IR name ,
a number, or one of the special characters listed below under
.BR "Special Parameters" .
-For the shell's purposes, a
+A
.I variable
is a parameter denoted by a
.IR name .
+A variable has a \fIvalue\fP and zero or more \fIattributes\fP.
+Attributes are assigned using the
+.B declare
+builtin command (see
+.B declare
+below in
+.SM
+.BR "SHELL BUILTIN COMMANDS" ).
.PP
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
.I value
is not given, the variable is assigned the null string. All
.I values
-undergo tilde expansion, parameter and variable expansion, string
-expansion, command substitution, arithmetic expansion, and quote
+undergo tilde expansion, parameter and variable expansion,
+command substitution, arithmetic expansion, and quote
removal (see
.SM
.B EXPANSION
below). If the variable has its
.B integer
-attribute set (see
-.B declare
-below in
-.SM
-.BR "SHELL BUILTIN COMMANDS" )
-then
+attribute set, then
.I value
-is subject to arithmetic expansion even if the $((...)) expansion is
+is evaluated as an arithmetic expression even if the $((...)) expansion is
not used (see
.B "Arithmetic Expansion"
below).
of \fB"$@"\fP as explained below under
.BR "Special Parameters" .
Pathname expansion is not performed.
+Assignment statements may also appear as arguments to the
+.BR alias ,
+.BR declare ,
+.BR typeset ,
+.BR export ,
+.BR readonly ,
+and
+.B local
+builtin commands.
+.PP
+In the context where an assignment statement is assigning a value
+to a shell variable or array index, the += operator can be used to
+append to or add to the variable's previous value.
+When += is applied to a variable for which the integer attribute has been
+set, \fIvalue\fP is evaluated as an arithmetic expression and added to the
+variable's current value, which is also evaluated.
+When += is applied to an array variable using compound assignment (see
+.B Arrays
+below), the
+variable's value is not unset (as it is when using =), and new values are
+appended to the array beginning at one greater than the array's maximum index
+(for indexed arrays) or added as additional key\-value pairs in an
+associative array.
+When applied to a string-valued variable, \fIvalue\fP is expanded and
+appended to the variable's value.
.SS Positional Parameters
.PP
A
expansion occurs within double quotes, each parameter expands to a
separate word. That is, "\fB$@\fP" is equivalent to
"\fB$1\fP" "\fB$2\fP" ...
+If the double-quoted expansion occurs within a word, the expansion of
+the first parameter is joined with the beginning part of the original
+word, and the expansion of the last parameter is joined with the last
+part of the original word.
When there are no positional parameters, "\fB$@\fP" and
.B $@
expand to nothing (i.e., they are removed).
Expands to the number of positional parameters in decimal.
.TP
.B ?
-Expands to the status of the most recently executed foreground
+Expands to the exit status of the most recently executed foreground
pipeline.
.TP
.B \-
as given by argument zero.
.TP
.B _
-At shell startup, set to the absolute file name of the shell or shell
-script being executed as passed in the argument list.
+At shell startup, set to the absolute pathname used to invoke the
+shell or shell script being executed as passed in the environment
+or argument list.
Subsequently, expands to the last argument to the previous command,
after expansion.
-Also set to the full file name of each command executed and placed in
-the environment exported to that command.
+Also set to the full pathname used to invoke each command executed
+and placed in the environment exported to that command.
When checking mail, this parameter holds the name of the mail file
currently being checked.
.PD
.PP
.PD 0
.TP
-.B PPID
-The process ID of the shell's parent. This variable is readonly.
-.TP
-.B PWD
-The current working directory as set by the
-.B cd
-command.
-.TP
-.B OLDPWD
-The previous working directory as set by the
-.B cd
-command.
-.TP
-.B REPLY
-Set to the line of input read by the
-.B read
-builtin command when no arguments are supplied.
-.TP
-.B UID
-Expands to the user ID of the current user, initialized at shell startup.
-This variable is readonly.
-.TP
-.B EUID
-Expands to the effective user ID of the current user, initialized at
-shell startup. This variable is readonly.
-.TP
-.B GROUPS
-An array variable containing the list of groups of which the current
-user is a member. This variable is readonly.
-.TP
.B BASH
Expands to the full file name used to invoke this instance of
.BR bash .
.TP
-.B BASH_VERSION
-Expands to a string describing the version of this instance of
-.BR bash .
+.B BASHPID
+Expands to the process id of the current \fBbash\fP process.
+This differs from \fB$$\fP under certain circumstances, such as subshells
+that do not require \fBbash\fP to be re-initialized.
+.TP
+.B BASH_ALIASES
+An associative array variable whose members correspond to the internal
+list of aliases as maintained by the \fBalias\fP builtin
+Elements added to this array appear in the alias list; unsetting array
+elements cause aliases to be removed from the alias list.
+.TP
+.B BASH_ARGC
+An array variable whose values are the number of parameters in each
+frame of the current \fBbash\fP execution call stack.
+The number of
+parameters to the current subroutine (shell function or script executed
+with \fB.\fP or \fBsource\fP) is at the top of the stack.
+When a subroutine is executed, the number of parameters passed is pushed onto
+\fBBASH_ARGC\fP.
+The shell sets \fBBASH_ARGC\fP only when in extended debugging mode
+(see the description of the
+.B extdebug
+option to the
+.B shopt
+builtin below)
+.TP
+.B BASH_ARGV
+An array variable containing all of the parameters in the current \fBbash\fP
+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 \fBBASH_ARGV\fP.
+The shell sets \fBBASH_ARGV\fP only when in extended debugging mode
+(see the description of the
+.B extdebug
+option to the
+.B shopt
+builtin below)
+.TP
+.B BASH_CMDS
+An associative array variable whose members correspond to the internal
+hash table of commands as maintained by the \fBhash\fP builtin.
+Elements added to this array appear in the hash table; unsetting array
+elements cause commands to be removed from the hash table.
+.TP
+.B 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.
+.TP
+.B BASH_EXECUTION_STRING
+The command argument to the \fB\-c\fP invocation option.
+.TP
+.B BASH_LINENO
+An array variable whose members are the line numbers in source files
+corresponding to each member of \fBFUNCNAME\fP.
+\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP is the line number in the source
+file where \fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called
+(or \fB${BASH_LINENO[\fP\fI$i-1\fP\fB]}\fP if referenced within another
+shell function).
+The corresponding source file name is \fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fB.
+Use \fBLINENO\fP to obtain the current line number.
+.TP
+.B BASH_REMATCH
+An array variable whose members are assigned by the \fB=~\fP binary
+operator to the \fB[[\fP conditional command.
+The element with index 0 is the portion of the string
+matching the entire regular expression.
+The element with index \fIn\fP is the portion of the
+string matching the \fIn\fPth parenthesized subexpression.
+This variable is read-only.
+.TP
+.B BASH_SOURCE
+An array variable whose members are the source filenames corresponding
+to the elements in the \fBFUNCNAME\fP array variable.
+.TP
+.B BASH_SUBSHELL
+Incremented by one each time a subshell or subshell environment is spawned.
+The initial value is 0.
.TP
.B BASH_VERSINFO
A readonly array variable whose members hold version information for
.PD
.RE
.TP
-.B SHLVL
-Incremented by one each time an instance of
-.B bash
-is started.
+.B BASH_VERSION
+Expands to a string describing the version of this instance of
+.BR bash .
.TP
-.B RANDOM
-Each time this parameter is referenced, a random integer between
-0 and 32767 is
-generated. The sequence of random numbers may be initialized by assigning
-a value to
-.SM
-.BR RANDOM .
-If
-.SM
-.B RANDOM
-is unset, it loses its special properties, even if it is
-subsequently reset.
+.B COMP_CWORD
+An index into \fB${COMP_WORDS}\fP of the word containing the current
+cursor position.
+This variable is available only in shell functions invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
.TP
-.B SECONDS
-Each time this parameter is
-referenced, the number of seconds since shell invocation is returned. If a
-value is assigned to
-.SM
-.BR SECONDS ,
-the value returned upon subsequent
-references is
-the number of seconds since the assignment plus the value assigned.
-If
-.SM
-.B SECONDS
-is unset, it loses its special properties, even if it is
-subsequently reset.
+.B COMP_KEY
+The key (or final key of a key sequence) used to invoke the current
+completion function.
.TP
-.B LINENO
-Each time this parameter is referenced, the shell substitutes
-a decimal number representing the current sequential line number
-(starting with 1) within a script or function. When not in a
-script or function, the value substituted is not guaranteed to
-be meaningful.
-If
-.SM
-.B LINENO
-is unset, it loses its special properties, even if it is
-subsequently reset.
+.B COMP_LINE
+The current command line.
+This variable is available only in shell functions and external
+commands invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
.TP
-.B HISTCMD
-The history number, or index in the history list, of the current
-command.
+.B COMP_POINT
+The index of the current cursor position relative to the beginning of
+the current command.
+If the current cursor position is at the end of the current command,
+the value of this variable is equal to \fB${#COMP_LINE}\fP.
+This variable is available only in shell functions and external
+commands invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
+.TP
+.B COMP_TYPE
+Set to an integer value corresponding to the type of completion attempted
+that caused a completion function to be called:
+\fITAB\fP, for normal completion,
+\fI?\fP, for listing completions after successive tabs,
+\fI!\fP, for listing alternatives on partial word completion,
+\fI@\fP, to list completions if the word is not unmodified,
+or
+\fI%\fP, for menu completion.
+This variable is available only in shell functions and external
+commands invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
+.TP
+.B COMP_WORDBREAKS
+The set of characters that the Readline library treats as word
+separators when performing word completion.
If
.SM
-.B HISTCMD
+.B COMP_WORDBREAKS
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
+.B COMP_WORDS
+An array variable (see \fBArrays\fP below) consisting of the individual
+words in the current command line.
+The words are split on shell metacharacters as the shell parser would
+separate them.
+This variable is available only in shell functions invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
+.TP
.B DIRSTACK
An array variable (see
.B Arrays
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
-.B PIPESTATUS
-An array variable (see
-.B Arrays
-below) containing a list of exit status values from the processes
-in the most-recently-executed foreground pipeline (which may
-contain only a single command).
+.B EUID
+Expands to the effective user ID of the current user, initialized at
+shell startup. This variable is readonly.
.TP
-.B OPTARG
-The value of the last option argument processed by the
-.B getopts
-builtin command (see
+.B 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
+.if t \f(CW"main"\fP.
+.if n "main".
+This variable exists only when a shell function is executing.
+Assignments to
+.SM
+.B FUNCNAME
+have no effect and return an error status.
+If
.SM
-.B SHELL BUILTIN COMMANDS
-below).
+.B FUNCNAME
+is unset, it loses its special properties, even if it is
+subsequently reset.
.TP
-.B OPTIND
-The index of the next argument to be processed by the
-.B getopts
-builtin command (see
+.B GROUPS
+An array variable containing the list of groups of which the current
+user is a member.
+Assignments to
.SM
-.B SHELL BUILTIN COMMANDS
-below).
+.B GROUPS
+have no effect and return an error status.
+If
+.SM
+.B GROUPS
+is unset, it loses its special properties, even if it is
+subsequently reset.
+.TP
+.B HISTCMD
+The history number, or index in the history list, of the current
+command.
+If
+.SM
+.B HISTCMD
+is unset, it loses its special properties, even if it is
+subsequently reset.
.TP
.B HOSTNAME
Automatically set to the name of the current host.
is executing.
The default is system-dependent.
.TP
-.B OSTYPE
-Automatically set to a string that
-describes the operating system on which
-.B bash
-is executing.
-The default is system-dependent.
+.B LINENO
+Each time this parameter is referenced, the shell substitutes
+a decimal number representing the current sequential line number
+(starting with 1) within a script or function. When not in a
+script or function, the value substituted is not guaranteed to
+be meaningful.
+If
+.SM
+.B LINENO
+is unset, it loses its special properties, even if it is
+subsequently reset.
.TP
.B MACHTYPE
Automatically set to a string that fully describes the system
is executing, in the standard GNU \fIcpu-company-system\fP format.
The default is system-dependent.
.TP
+.B OLDPWD
+The previous working directory as set by the
+.B cd
+command.
+.TP
+.B OPTARG
+The value of the last option argument processed by the
+.B getopts
+builtin command (see
+.SM
+.B SHELL BUILTIN COMMANDS
+below).
+.TP
+.B OPTIND
+The index of the next argument to be processed by the
+.B getopts
+builtin command (see
+.SM
+.B SHELL BUILTIN COMMANDS
+below).
+.TP
+.B OSTYPE
+Automatically set to a string that
+describes the operating system on which
+.B bash
+is executing.
+The default is system-dependent.
+.TP
+.B PIPESTATUS
+An array variable (see
+.B Arrays
+below) containing a list of exit status values from the processes
+in the most-recently-executed foreground pipeline (which may
+contain only a single command).
+.TP
+.B PPID
+The process ID of the shell's parent. This variable is readonly.
+.TP
+.B PWD
+The current working directory as set by the
+.B cd
+command.
+.TP
+.B RANDOM
+Each time this parameter is referenced, a random integer between
+0 and 32767 is
+generated. The sequence of random numbers may be initialized by assigning
+a value to
+.SM
+.BR RANDOM .
+If
+.SM
+.B RANDOM
+is unset, it loses its special properties, even if it is
+subsequently reset.
+.TP
+.B REPLY
+Set to the line of input read by the
+.B read
+builtin command when no arguments are supplied.
+.TP
+.B SECONDS
+Each time this parameter is
+referenced, the number of seconds since shell invocation is returned. If a
+value is assigned to
+.SM
+.BR SECONDS ,
+the value returned upon subsequent
+references is
+the number of seconds since the assignment plus the value assigned.
+If
+.SM
+.B SECONDS
+is unset, it loses its special properties, even if it is
+subsequently reset.
+.TP
.B SHELLOPTS
A colon-separated list of enabled shell options. Each word in
the list is a valid argument for the
starts up, each shell option in the list will be enabled before
reading any startup files.
This variable is read-only.
+.TP
+.B SHLVL
+Incremented by one each time an instance of
+.B bash
+is started.
+.TP
+.B UID
+Expands to the user ID of the current user, initialized at shell startup.
+This variable is readonly.
.PD
.PP
The following variables are used by the shell. In some cases,
.PP
.PD 0
.TP
-.B IFS
-The
-.I Internal Field Separator
-that is used
-for word splitting after expansion and to
-split lines into words with the
-.B read
-builtin command. The default value is
-``<space><tab><newline>''.
-.TP
-.B PATH
-The search path for commands. It
-is a colon-separated list of directories in which
-the shell looks for commands (see
-.SM
-.B COMMAND EXECUTION
-below). The default path is system-dependent,
-and is set by the administrator who installs
-.BR bash .
-A common value is ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin:.''.
-.TP
-.B HOME
-The home directory of the current user; the default argument for the
-\fBcd\fP builtin command.
-The value of this variable is also used when performing tilde expansion.
-.TP
-.B CDPATH
-The search path for the
-.B cd
-command.
-This is a colon-separated list of directories in which the shell looks
-for destination directories specified by the
-.B cd
-command.
-A sample value is ``.:~:/usr''.
-.TP
.B BASH_ENV
If this parameter is set when \fBbash\fP is executing a shell script,
its value is interpreted as a filename containing commands to
.B PATH
is not used to search for the resultant file name.
.TP
-.B MAIL
-If this parameter is set to a file name and the
-.SM
-.B MAILPATH
-variable is not set,
-.B bash
-informs the user of the arrival of mail in the specified file.
-.TP
-.B MAILCHECK
-Specifies how
-often (in seconds)
-.B bash
-checks for mail. The default is 60 seconds. When it is time to check
-for mail, the shell does so before displaying the primary prompt.
-If this variable is unset, the shell disables mail checking.
+.B CDPATH
+The search path for the
+.B cd
+command.
+This is a colon-separated list of directories in which the shell looks
+for destination directories specified by the
+.B cd
+command.
+A sample value is
+.if t \f(CW".:~:/usr"\fP.
+.if n ".:~:/usr".
+.TP
+.B COLUMNS
+Used by the \fBselect\fP builtin command to determine the terminal width
+when printing selection lists. Automatically set upon receipt of a SIGWINCH.
+.TP
+.B COMPREPLY
+An array variable from which \fBbash\fP reads the possible completions
+generated by a shell function invoked by the programmable completion
+facility (see \fBProgrammable Completion\fP below).
+.TP
+.B EMACS
+If \fBbash\fP finds this variable in the environment when the shell starts
+with value
+.if t \f(CWt\fP,
+.if n "t",
+it assumes that the shell is running in an emacs shell buffer and disables
+line editing.
.TP
-.B MAILPATH
-A colon-separated list of file names to be checked for mail.
-The message to be printed when mail arrives in a particular file
-may be specified by separating the file name from the message with a `?'.
-When used in the text of the message, \fB$_\fP expands to the name of
-the current mailfile.
-Example:
-.RS
-.PP
-\fBMAILPATH\fP='/usr/spool/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"'
-.PP
-.B Bash
-supplies a default value for this variable, but the location of the user
-mail files that it uses is system dependent (e.g., /usr/spool/mail/\fB$USER\fP).
-.RE
+.B FCEDIT
+The default editor for the
+.B fc
+builtin command.
.TP
-.B PS1
-The value of this parameter is expanded (see
+.B FIGNORE
+A colon-separated list of suffixes to ignore when performing
+filename completion (see
.SM
-.B PROMPTING
-below) and used as the primary prompt string. The default value is
-``\fB\es\-\ev\e$ \fP''.
-.TP
-.B PS2
-The value of this parameter is expanded as with
-.B PS1
-and used as the secondary prompt string. The default is
-``\fB> \fP''.
-.TP
-.B PS3
-The value of this parameter is used as the prompt for the
-.B select
-command (see
+.B READLINE
+below).
+A filename whose suffix matches one of the entries in
.SM
-.B SHELL GRAMMAR
-above).
+.B FIGNORE
+is excluded from the list of matched filenames.
+A sample value is
+.if t \f(CW".o:~"\fP.
+.if n ".o:~".
.TP
-.B PS4
-The value of this parameter is expanded as with
-.B PS1
-and the value is printed before each command
-.B bash
-displays during an execution trace. The first character of
+.B GLOBIGNORE
+A colon-separated list of patterns defining the set of filenames to
+be ignored by pathname expansion.
+If a filename matched by a pathname expansion pattern also matches one
+of the patterns in
.SM
-.B PS4
-is replicated multiple times, as necessary, to indicate multiple
-levels of indirection. The default is ``\fB+ \fP''.
-.TP
-.B TIMEFORMAT
-The value of this parameter is used as a format string specifying
-how the timing information for pipelines prefixed with the
-.B time
-reserved word should be displayed.
-The \fB%\fP 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.
-.sp .5
-.RS
-.PD 0
-.TP 10
-.B %%
-A literal \fB%\fP.
-.TP
-.B %[\fIp\fP][l]R
-The elapsed time in seconds.
-.TP
-.B %[\fIp\fP][l]U
-The number of CPU seconds spent in user mode.
-.TP
-.B %[\fIp\fP][l]S
-The number of CPU seconds spent in system mode.
-.TP
-.B %P
-The CPU percentage, computed as (%U + %S) / %R.
-.PD
-.RE
-.IP
-The optional \fIp\fP is a digit specifying the \fIprecision\fP,
-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 \fIp\fP greater than 3 are changed to 3.
-If \fIp\fP is not specified, the value 3 is used.
-.IP
-The optional \fBl\fP specifies a longer format, including
-minutes, of the form \fIMM\fPm\fISS\fP.\fIFF\fPs.
-The value of \fIp\fP determines whether or not the fraction is
-included.
-.IP
-If this variable is not set, \fBbash\fP acts as if it had the
-value \fB$'\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS'\fP.
-If the value is null, no timing information is displayed.
-A trailing newline is added when the format string is displayed.
+.BR GLOBIGNORE ,
+it is removed from the list of matches.
.TP
-.B HISTSIZE
-The number of commands to remember in the command history (see
-.SM
-.B HISTORY
-below). The default value is 500.
+.B HISTCONTROL
+A colon-separated list of values controlling how commands are saved on
+the history list.
+If the list of values includes
+.IR ignorespace ,
+lines which begin with a
+.B space
+character are not saved in the history list.
+A value of
+.I ignoredups
+causes lines matching the previous history entry to not be saved.
+A value of
+.I ignoreboth
+is shorthand for \fIignorespace\fP and \fIignoredups\fP.
+A value of
+.IR 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 \fBHISTCONTROL\fP 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
+.BR 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
+.BR HISTCONTROL .
.TP
.B HISTFILE
The name of the file in which command history is saved (see
.B HISTFILESIZE
The maximum number of lines contained in the history file. When this
variable is assigned a value, the history file is truncated, if
-necessary, to contain no more than that number of lines. The default
+necessary, by removing the oldest entries,
+to contain no more than that number of lines. The default
value is 500. The history file is also truncated to this size after
writing it when an interactive shell exits.
.TP
-.B OPTERR
-If set to the value 1,
+.B 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
+`\fB*\fP' is appended). Each pattern is tested against the line
+after the checks specified by
+.B HISTCONTROL
+are applied.
+In addition to the normal shell pattern matching characters, `\fB&\fP'
+matches the previous history line. `\fB&\fP' 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
+.BR HISTIGNORE .
+.TP
+.B HISTSIZE
+The number of commands to remember in the command history (see
+.SM
+.B HISTORY
+below). The default value is 500.
+.TP
+.B HISTTIMEFORMAT
+If this variable is set and not null, its value is used as a format string
+for \fIstrftime\fP(3) to print the time stamp associated with each history
+entry displayed by the \fBhistory\fP builtin.
+If this variable is set, time stamps are written to the history file so
+they may be preserved across shell sessions.
+This uses the history comment character to distinguish timestamps from
+other history lines.
+.TP
+.B HOME
+The home directory of the current user; the default argument for the
+\fBcd\fP builtin command.
+The value of this variable is also used when performing tilde expansion.
+.TP
+.B HOSTFILE
+Contains the name of a file in the same format as
+.FN /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,
.B bash
-displays error messages generated by the
-.B getopts
-builtin command (see
+adds the contents of the new file to the existing list.
+If
.SM
-.B SHELL BUILTIN COMMANDS
-below).
+.B HOSTFILE
+is set, but has no value, \fBbash\fP attempts to read
+.FN /etc/hosts
+to obtain the list of possible hostname completions.
+When
.SM
-.B OPTERR
-is initialized to 1 each time the shell is invoked or a shell
-script is executed.
+.B HOSTFILE
+is unset, the hostname list is cleared.
+.TP
+.B IFS
+The
+.I Internal Field Separator
+that is used
+for word splitting after expansion and to
+split lines into words with the
+.B read
+builtin command. The default value is
+``<space><tab><newline>''.
+.TP
+.B IGNOREEOF
+Controls the
+action of an interactive shell on receipt of an
+.SM
+.B EOF
+character as the sole input. If set, the value is the number of
+consecutive
+.SM
+.B EOF
+characters which must be
+typed as the first characters on an input line before
+.B bash
+exits. If the variable exists but does not have a numeric value, or
+has no value, the default value is 10. If it does not exist,
+.SM
+.B EOF
+signifies the end of input to the shell.
+.TP
+.B INPUTRC
+The filename for the
+.B readline
+startup file, overriding the default of
+.FN ~/.inputrc
+(see
+.SM
+.B READLINE
+below).
.TP
.B LANG
Used to determine the locale category for any category not specifically
This variable determines the locale used to translate double-quoted
strings preceded by a \fB$\fP.
.TP
-.B PROMPT_COMMAND
-If set, the value is executed as a command prior to issuing each primary
-prompt.
+.B LC_NUMERIC
+This variable determines the locale category used for number formatting.
.TP
-.B IGNOREEOF
-Controls the
-action of an interactive shell on receipt of an
-.SM
-.B EOF
-character as the sole input. If set, the value is the number of
-consecutive
+.B LINES
+Used by the \fBselect\fP builtin command to determine the column length
+for printing selection lists. Automatically set upon receipt of a SIGWINCH.
+.TP
+.B MAIL
+If this parameter is set to a file name and the
.SM
-.B EOF
-characters which must be
-typed as the first characters on an input line before
+.B MAILPATH
+variable is not set,
.B bash
-exits. If the variable exists but does not have a numeric value, or
-has no value, the default value is 10. If it does not exist,
-.SM
-.B EOF
-signifies the end of input to the shell.
+informs the user of the arrival of mail in the specified file.
.TP
-.B TMOUT
-If set to a value greater than zero, the value is interpreted as the
-number of seconds to wait for input after issuing the primary prompt.
+.B MAILCHECK
+Specifies how
+often (in seconds)
+.B bash
+checks for mail. The default is 60 seconds. When it is time to check
+for mail, the shell does so before displaying the primary prompt.
+If this variable is unset, or set to a value that is not a number
+greater than or equal to zero, the shell disables mail checking.
+.TP
+.B MAILPATH
+A colon-separated list of file names to be checked for mail.
+The message to be printed when mail arrives in a particular file
+may be specified by separating the file name from the message with a `?'.
+When used in the text of the message, \fB$_\fP expands to the name of
+the current mailfile.
+Example:
+.RS
+.PP
+\fBMAILPATH\fP=\(aq/var/mail/bfox?"You have mail":~/shell\-mail?"$_ has mail!"\(aq
+.PP
.B Bash
-terminates after waiting for that number of seconds if input does
-not arrive.
+supplies a default value for this variable, but the location of the user
+mail files that it uses is system dependent (e.g., /var/mail/\fB$USER\fP).
+.RE
.TP
-.B FCEDIT
-The default editor for the
-.B fc
-builtin command.
+.B OPTERR
+If set to the value 1,
+.B bash
+displays error messages generated by the
+.B getopts
+builtin command (see
+.SM
+.B SHELL BUILTIN COMMANDS
+below).
+.SM
+.B OPTERR
+is initialized to 1 each time the shell is invoked or a shell
+script is executed.
.TP
-.B FIGNORE
-A colon-separated list of suffixes to ignore when performing
-filename completion (see
+.B PATH
+The search path for commands. It
+is a colon-separated list of directories in which
+the shell looks for commands (see
.SM
-.B READLINE
+.B COMMAND EXECUTION
below).
-A filename whose suffix matches one of the entries in
-.SM
-.B FIGNORE
-is excluded from the list of matched filenames.
-A sample value is ``.o:~''.
+A zero-length (null) directory name in the value of \fBPATH\fP indicates the
+current directory.
+A null directory name may appear as two adjacent colons, or as an initial
+or trailing colon.
+The default path is system-dependent,
+and is set by the administrator who installs
+.BR bash .
+A common value is
+.if t \f(CW/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin\fP.
+.if n ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''.
.TP
-.B GLOBIGNORE
-A colon-separated list of patterns defining the set of filenames to
-be ignored by pathname expansion.
-If a filename matched by a pathname expansion pattern also matches one
-of the patterns in
+.B POSIXLY_CORRECT
+If this variable is in the environment when \fBbash\fP starts, the shell
+enters \fIposix mode\fP before reading the startup files, as if the
+.B \-\-posix
+invocation option had been supplied. If it is set while the shell is
+running, \fBbash\fP enables \fIposix mode\fP, as if the command
+.if t \f(CWset -o posix\fP
+.if n \fIset -o posix\fP
+had been executed.
+.TP
+.B PROMPT_COMMAND
+If set, the value is executed as a command prior to issuing each primary
+prompt.
+.TP
+.B PROMPT_DIRTRIM
+If set to a number greater than zero, the value is used as the number of
+trailing directory components to retain when expanding the \fB\ew\fB and
+\fB\eW\fP prompt string escapes (see
.SM
-.BR GLOBIGNORE ,
-it is removed from the list of matches.
+.B PROMPTING
+below). Characters removed are replaced with an ellipsis.
.TP
-.B INPUTRC
-The filename for the
-.B readline
-startup file, overriding the default of
-.FN ~/.inputrc
-(see
+.B PS1
+The value of this parameter is expanded (see
.SM
-.B READLINE
-below).
+.B PROMPTING
+below) and used as the primary prompt string. The default value is
+``\fB\es\-\ev\e$ \fP''.
.TP
-.B HISTCONTROL
-If set to a value of
-.IR ignorespace ,
-lines which begin with a
-.B space
-character are not entered on the history list. If set to
-a value of
-.IR ignoredups ,
-lines matching the last history line are not entered.
-A value of
-.I ignoreboth
-combines the two options.
-If unset, or if set to any other value than those above,
-all lines read
-by the parser are saved on the history list, subject to the value
-of
-.BR HISTIGNORE .
-This variable's function is superseded by
-.BR 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
-.BR HISTCONTROL .
+.B PS2
+The value of this parameter is expanded as with
+.B PS1
+and used as the secondary prompt string. The default is
+``\fB> \fP''.
.TP
-.B 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 fully specify the line (no implicit
-`\fB*\fP' is appended). Each pattern is tested against the line
-after the checks specified by
-.B HISTCONTROL
-are applied.
-In addition to the normal shell pattern matching characters, `\fB&\fP'
-matches the previous history line. `\fB&\fP' 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
-.BR HISTIGNORE .
+.B PS3
+The value of this parameter is used as the prompt for the
+.B select
+command (see
+.SM
+.B SHELL GRAMMAR
+above).
.TP
-.B histchars
-The two or three characters which control history expansion
-and tokenization (see
+.B PS4
+The value of this parameter is expanded as with
+.B PS1
+and the value is printed before each command
+.B bash
+displays during an execution trace. The first character of
.SM
-.B HISTORY EXPANSION
-below). The first character is the
-.IR "history expansion character" ,
-the character which signals the start of a history
-expansion, normally `\fB!\fP'.
-The second character is the
-.IR "quick substitution"
-character, which is used as shorthand for re-running the previous
-command entered, substituting one string for another in the command.
-The default is `\fB^\fP'.
-The optional third character is the character
-which indicates that the remainder of the line is a comment when found
-as the first character of a word, normally `\fB#\fP'. 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.
+.B PS4
+is replicated multiple times, as necessary, to indicate multiple
+levels of indirection. The default is ``\fB+ \fP''.
.TP
-.B HOSTFILE
-Contains the name of a file in the same format as
-.FN /etc/hosts
-that should be read when the shell needs to complete a
-hostname. The file may be changed interactively; the next
-time hostname completion is attempted
+.B SHELL
+The full pathname to the shell is kept in this environment variable.
+If it is not set when the shell starts,
.B bash
-adds the contents of the new file to the already existing database.
+assigns to it the full pathname of the current user's login shell.
+.TP
+.B TIMEFORMAT
+The value of this parameter is used as a format string specifying
+how the timing information for pipelines prefixed with the
+.B time
+reserved word should be displayed.
+The \fB%\fP 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.
+.sp .5
+.RS
+.PD 0
+.TP 10
+.B %%
+A literal \fB%\fP.
+.TP
+.B %[\fIp\fP][l]R
+The elapsed time in seconds.
+.TP
+.B %[\fIp\fP][l]U
+The number of CPU seconds spent in user mode.
+.TP
+.B %[\fIp\fP][l]S
+The number of CPU seconds spent in system mode.
+.TP
+.B %P
+The CPU percentage, computed as (%U + %S) / %R.
+.PD
+.RE
+.IP
+The optional \fIp\fP is a digit specifying the \fIprecision\fP,
+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 \fIp\fP greater than 3 are changed to 3.
+If \fIp\fP is not specified, the value 3 is used.
+.IP
+The optional \fBl\fP specifies a longer format, including
+minutes, of the form \fIMM\fPm\fISS\fP.\fIFF\fPs.
+The value of \fIp\fP determines whether or not the fraction is
+included.
+.IP
+If this variable is not set, \fBbash\fP acts as if it had the
+value \fB$\(aq\enreal\et%3lR\enuser\et%3lU\ensys\t%3lS\(aq\fP.
+If the value is null, no timing information is displayed.
+A trailing newline is added when the format string is displayed.
+.TP
+.B TMOUT
+If set to a value greater than zero, \fBTMOUT\fP is treated as the
+default timeout for the \fBread\fP builtin.
+The \fBselect\fP command terminates if input does not arrive
+after \fBTMOUT\fP seconds when input is coming from a terminal.
+In an interactive shell, the value is interpreted as the
+number of seconds to wait for input after issuing the primary prompt.
+.B Bash
+terminates after waiting for that number of seconds if input does
+not arrive.
+.TP
+.B TMPDIR
+If set, \fBBash\fP uses its value as the name of a directory in which
+\fBBash\fP creates temporary files for the shell's use.
.TP
.B auto_resume
This variable controls how the shell interacts with the user and
.B JOB CONTROL
below). If set to any other value, the supplied string must
be a prefix of a stopped job's name; this provides functionality
-analogous to the
-.B %
-job identifier.
+analogous to the \fB%\fP\fIstring\fP job identifier.
+.TP
+.B histchars
+The two or three characters which control history expansion
+and tokenization (see
+.SM
+.B HISTORY EXPANSION
+below). The first character is the \fIhistory expansion\fP character,
+the character which signals the start of a history
+expansion, normally `\fB!\fP'.
+The second character is the \fIquick substitution\fP
+character, which is used as shorthand for re-running the previous
+command entered, substituting one string for another in the command.
+The default is `\fB^\fP'.
+The optional third character is the character
+which indicates that the remainder of the line is a comment when found
+as the first character of a word, normally `\fB#\fP'. 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.
.PD
.SS Arrays
.B Bash
-provides one-dimensional array variables. Any variable may be used as
-an array; the
+provides one-dimensional indexed and associative array variables.
+Any variable may be used as an indexed array; the
.B declare
-builtin will explicitly declare an array. There is no maximum
+builtin will explicitly declare an array.
+There is no maximum
limit on the size of an array, nor any requirement that members
-be indexed or assigned contiguously. Arrays are indexed using
-integers and are zero-based.
+be indexed or assigned contiguously.
+Indexed arrays are referenced using integers (including arithmetic
+expressions) and are zero-based; associative arrays are referenced
+using arbitrary strings.
.PP
-An array is created automatically if any variable is assigned to using
-the syntax \fIname\fP[\fIsubscript\fP]=\fIvalue\fP. The
+An indexed array is created automatically if any variable is assigned to
+using the syntax \fIname\fP[\fIsubscript\fP]=\fIvalue\fP. The
.I 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
+greater than or equal to zero. To explicitly declare an indexed array,
+use
.B declare \-a \fIname\fP
(see
.SM
.B SHELL BUILTIN COMMANDS
below).
.B declare \-a \fIname\fP[\fIsubscript\fP]
-is also accepted; the \fIsubscript\fP is ignored. Attributes may be
+is also accepted; the \fIsubscript\fP is ignored.
+.PP
+Associative arrays are created using
+.BR "declare \-A \fIname\fP" .
+.PP
+Attributes may be
specified for an array variable using the
.B declare
and
.PP
Arrays are assigned to using compound assignments of the form
\fIname\fP=\fB(\fPvalue\fI1\fP ... value\fIn\fP\fB)\fP, where each
-\fIvalue\fP is of the form [\fIsubscript\fP]=\fIstring\fP. Only
-\fIstring\fP is required. If
-the optional brackets and subscript are supplied, that index is assigned to;
+\fIvalue\fP is of the form [\fIsubscript\fP]=\fIstring\fP.
+Indexed array assignments do not require the bracket and subscript.
+When assigning to indexed arrays, if the optional brackets and subscript
+are supplied, that index is assigned to;
otherwise the index of the element assigned is the last index assigned
to by the statement plus one. Indexing starts at zero.
+.PP
+When assigning to an associative array, the subscript is required.
+.PP
This syntax is also accepted by the
.B declare
builtin. Individual array elements may be assigned to using the
.B IFS
special variable, and ${\fIname\fP[@]} expands each element of
\fIname\fP to a separate word. When there are no array members,
-${\fIname\fP[@]} expands to nothing. This is analogous to the expansion
+${\fIname\fP[@]} expands to nothing.
+If the double-quoted expansion occurs within a word, the expansion of
+the first parameter is joined with the beginning part of the original
+word, and the expansion of the last parameter is joined with the last
+part of the original word.
+This is analogous to the expansion
of the special parameters \fB*\fP and \fB@\fP (see
.B Special Parameters
above). ${#\fIname\fP[\fIsubscript\fP]} expands to the length of
${\fIname\fP[\fIsubscript\fP]}. If \fIsubscript\fP is \fB*\fP or
\fB@\fP, the expansion is the number of elements in the array.
Referencing an array variable without a subscript is equivalent to
-referencing element zero.
+referencing the array with a subscript of 0.
.PP
The
.B unset
-builtin is used to destroy arrays. \fBunset\fP \fBname\fP[\fIsubscript\fP]
+builtin is used to destroy arrays. \fBunset\fP \fIname\fP[\fIsubscript\fP]
destroys the array element at index \fIsubscript\fP.
+Care must be taken to avoid unwanted side effects caused by filename
+generation.
\fBunset\fP \fIname\fP, where \fIname\fP is an array, or
\fBunset\fP \fIname\fP[\fIsubscript\fP], where
\fIsubscript\fP is \fB*\fP or \fB@\fP, removes the entire array.
.B readonly
builtins each accept a
.B \-a
-option to specify an array. The
+option to specify an indexed array and a
+.B \-A
+option to specify an associative array.
+The
.B read
builtin accepts a
.B \-a
need not exist. Patterns to be brace expanded take
the form of an optional
.IR preamble ,
-followed by a series of comma-separated strings
-between a pair of braces, followed by an optional
+followed by either a series of comma-separated strings or
+a sequence expression between a pair of braces, followed by
+an optional
.IR postscript .
The preamble is prefixed to each string contained
within the braces, and the postscript is then appended
string are not sorted; left to right order is preserved.
For example, a\fB{\fPd,c,b\fB}\fPe expands into `ade ace abe'.
.PP
+A sequence expression takes the form
+\fB{\fP\fIx\fP\fB..\fP\fIy\fP\fB[..\fP\fIincr\fP\fB]}\fP,
+where \fIx\fP and \fIy\fP are either integers or single characters,
+and \fIincr\fP, an optional increment, is an integer.
+When integers are supplied, the expression expands to each number between
+\fIx\fP and \fIy\fP, inclusive.
+Supplied integers may be prefixed with \fI0\fP to force each term to have the
+same width. When either \fIx\fP or \fPy\fP begins with a zero, the shell
+attempts to force all generated terms to contain the same number of digits,
+zero-padding where necessary.
+When characters are supplied, the expression expands to each character
+lexicographically between \fIx\fP and \fIy\fP, inclusive. Note that
+both \fIx\fP and \fIy\fP must be of the same type.
+When the increment is supplied, it is used as the difference between
+each term. The default increment is 1 or -1 as appropriate.
+.PP
Brace expansion is performed before any other expansions,
and any characters special to other expansions are preserved
in the result. It is strictly textual.
expansion or the text between the braces.
.PP
A correctly-formed brace expansion must contain unquoted opening
-and closing braces, and at least one unquoted comma.
+and closing braces, and at least one unquoted comma or a valid
+sequence expression.
Any incorrectly formed brace expansion is left unchanged.
A \fB{\fP or \fB,\fP may be quoted with a backslash to prevent its
being considered part of a brace expression.
+To avoid conflicts with parameter expansion, the string \fB${\fP
+is not considered eligible for brace expansion.
.PP
This construct is typically used as shorthand when the common
prefix of the strings to be generated is longer than in the
Each variable assignment is checked for unquoted tilde-prefixes immediately
following a
.B :
-or
+or the first
.BR = .
In these cases, tilde expansion is also performed.
Consequently, one may use file names with tildes in assignments to
.PP
When braces are used, the matching ending brace is the first `\fB}\fP'
not escaped by a backslash or within a quoted string, and not within an
-embedded arithmetic expansion, command substitution, or paramter
+embedded arithmetic expansion, command substitution, or parameter
expansion.
.PP
.PD 0
a level of variable indirection is introduced.
\fBBash\fP uses the value of the variable formed from the rest of
\fIparameter\fP as the name of the variable; this variable is then
-expanded and that value used in the rest of the substitution, rather
+expanded and that value is used in the rest of the substitution, rather
than the value of \fIparameter\fP itself.
This is known as \fIindirect expansion\fP.
+The exceptions to this are the expansions of ${!\fIprefix\fP*} and
+${\fB!\fP\fIname\fP[\fI@\fP]} described below.
+The exclamation point must immediately follow the left brace in order to
+introduce indirection.
.PP
In each of the cases below, \fIword\fP is subject to tilde expansion,
parameter expansion, command substitution, and arithmetic expansion.
.I word
is substituted.
.TP
-.PD 0
${\fIparameter\fP\fB:\fP\fIoffset\fP}
+.PD 0
.TP
${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP}
.PD
\fBSubstring Expansion.\fP
-Expands to up to \fIlength\fP characters of \fIparameter\fP,
-starting at the characters specified by \fIoffset\fP.
+Expands to up to \fIlength\fP characters of \fIparameter\fP
+starting at the character specified by \fIoffset\fP.
If \fIlength\fP is omitted, expands to the substring of
-\fIparameter\fP, starting at the character specified by \fIoffset\fP.
+\fIparameter\fP starting at the character specified by \fIoffset\fP.
\fIlength\fP and \fIoffset\fP are arithmetic expressions (see
.SM
.B
is used as an offset from the end of the value of \fIparameter\fP.
If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional
parameters beginning at \fIoffset\fP.
-If \fIparameter\fP is an array name indexed by @ or *,
+If \fIparameter\fP is an indexed array name subscripted by @ or *,
the result is the \fIlength\fP
members of the array beginning with ${\fIparameter\fP[\fIoffset\fP]}.
+A negative \fIoffset\fP is taken relative to one greater than the maximum
+index of the specified array.
+Substring expansion applied to an associative array produces undefined
+results.
+Note that a negative offset must be separated from the colon by at least
+one space to avoid being confused with the :- expansion.
Substring indexing is zero-based unless the positional parameters
-are used, in which case the indexing starts at 1.
+are used, in which case the indexing starts at 1 by default.
+If \fIoffset\fP is 0, and the positional parameters are used, \fB$0\fP is
+prefixed to the list.
+.TP
+${\fB!\fP\fIprefix\fP\fB*\fP}
+.PD 0
+.TP
+${\fB!\fP\fIprefix\fP\fB@\fP}
+.PD
+\fBNames matching prefix.\fP
+Expands to the names of variables whose names begin with \fIprefix\fP,
+separated by the first character of the
+.SM
+.B IFS
+special variable.
+When \fI@\fP is used and the expansion appears within double quotes, each
+variable name expands to a separate word.
+.TP
+${\fB!\fP\fIname\fP[\fI@\fP]}
+.PD 0
+.TP
+${\fB!\fP\fIname\fP[\fI*\fP]}
+.PD
+\fBList of array keys.\fP
+If \fIname\fP is an array variable, expands to the list of array indices
+(keys) assigned in \fIname\fP.
+If \fIname\fP is not an array, expands to 0 if \fIname\fP is set and null
+otherwise.
+When \fI@\fP is used and the expansion appears within double quotes, each
+key expands to a separate word.
.TP
${\fB#\fP\fIparameter\fP}
+\fBParameter length.\fP
The length in characters of the value of \fIparameter\fP is substituted.
If
.I parameter
.BR @ ,
the value substituted is the number of elements in the array.
.TP
-.PD 0
${\fIparameter\fP\fB#\fP\fIword\fP}
+.PD 0
.TP
${\fIparameter\fP\fB##\fP\fIword\fP}
.PD
+\fBRemove matching prefix pattern.\fP
The
.I word
is expanded to produce a pattern just as in pathname
the pattern removal operation is applied to each member of the
array in turn, and the expansion is the resultant list.
.TP
-.PD 0
${\fIparameter\fP\fB%\fP\fIword\fP}
+.PD 0
.TP
${\fIparameter\fP\fB%%\fP\fIword\fP}
.PD
+\fBRemove matching suffix pattern.\fP
The \fIword\fP is expanded to produce a pattern just as in
pathname expansion.
If the pattern matches a trailing portion of the expanded value of
the pattern removal operation is applied to each member of the
array in turn, and the expansion is the resultant list.
.TP
-.PD 0
${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP}
-.TP
-${\fIparameter\fP\fB//\fP\fIpattern\fP\fB/\fP\fIstring\fP}
-.PD
+\fBPattern substitution.\fP
The \fIpattern\fP is expanded to produce a pattern just as in
pathname expansion.
\fIParameter\fP is expanded and the longest match of \fIpattern\fP
against its value is replaced with \fIstring\fP.
-In the first form, only the first match is replaced.
-The second form causes all matches of \fIpattern\fP to be
-replaced with \fIstring\fP.
+If \fIpattern\fP begins with \fB/\fP, all matches of \fIpattern\fP are
+replaced with \fIstring\fP. Normally only the first match is replaced.
If \fIpattern\fP begins with \fB#\fP, it must match at the beginning
-of \fIstring\fP.
+of the expanded value of \fIparameter\fP.
If \fIpattern\fP begins with \fB%\fP, it must match at the end
-of \fIstring\fP.
+of the expanded value of \fIparameter\fP.
If \fIstring\fP is null, matches of \fIpattern\fP are deleted
and the \fB/\fP following \fIpattern\fP may be omitted.
If
.BR * ,
the substitution operation is applied to each member of the
array in turn, and the expansion is the resultant list.
+.TP
+${\fIparameter\fP\fB^\fP\fIpattern\fP}
+.PD 0
+.TP
+${\fIparameter\fP\fB^^\fP\fIpattern\fP}
+.TP
+${\fIparameter\fP\fB,\fP\fIpattern\fP}
+.TP
+${\fIparameter\fP\fB,,\fP\fIpattern\fP}
+.PD
+\fBCase modification.\fP
+This expansion modifies the case of alphabetic characters in \fIparameter\fP.
+The \fIpattern\fP is expanded to produce a pattern just as in
+pathname expansion.
+The \fB^\fP operator converts lowercase letters matching \fIpattern\fP
+to uppercase; the \fB,\fP operator converts matching uppercase letters
+to lowercase.
+The \fB^^\fP and \fB,,\fP expansions convert each matched character in the
+expanded value; the \fB^\fP and \fB,\fP expansions match and convert only
+the first character.
+If \fIpattern\fP is omitted, it is treated like a \fB?\fP, which matches
+every character.
+If
+.I parameter
+is
+.B @
+or
+.BR * ,
+the case modification operation is applied to each positional
+parameter in turn, and the expansion is the resultant list.
+If
+.I parameter
+is an array variable subscripted with
+.B @
+or
+.BR * ,
+the case modification operation is applied to each member of the
+array in turn, and the expansion is the resultant list.
.SS Command Substitution
.PP
\fICommand substitution\fP allows the output of a command to replace
.RE
or
.RS
-\fB`\fP\fIcommand\fP\fB`\fP
+\fB\`\fP\fIcommand\fP\fB\`\fP
.RE
.PP
.B Bash
When the old-style backquote form of substitution is used,
backslash retains its literal meaning except when followed by
.BR $ ,
-.BR ` ,
+.BR \` ,
or
.BR \e .
The first backquote not preceded by a backslash terminates the
inside the parentheses is not treated specially.
All tokens in the expression undergo parameter expansion, string
expansion, command substitution, and quote removal.
-Arithmetic substitutions may be nested.
+Arithmetic expansions may be nested.
.PP
The evaluation is performed according to the rules listed below under
.SM
\fB<(\fP\fIlist\^\fP\fB)\fP form is used, the file passed as an
argument should be read to obtain the output of \fIlist\fP.
.PP
-When available, \fIprocess substitution\fP is performed
+When available, process substitution is performed
simultaneously with parameter and variable expansion,
command substitution,
and arithmetic expansion.
value is exactly
.BR <space><tab><newline> ,
the default, then
+sequences of
+.BR <space> ,
+.BR <tab> ,
+and
+.B <newline>
+at the beginning and end of the results of the previous
+expansions are ignored, and
any sequence of
.SM
.B IFS
-characters serves to delimit words. If
+characters not at the beginning or end serves to delimit words.
+If
.SM
.B IFS
has a value other than the default, then sequences of
.B IFS
is null, no word splitting occurs.
.PP
-Explicit null arguments (\^\f3"\^"\fP or \^\f3'\^'\fP\^) are retained.
+Explicit null arguments (\^\f3"\^"\fP or \^\f3\(aq\^\(aq\fP\^) are retained.
Unquoted implicit null arguments, resulting from the expansion of
-.I parameters
-that have no values, are removed.
+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.
.PP
scans each word for the characters
.BR * ,
.BR ? ,
-.BR ( ,
and
.BR [ .
If one of these characters appears, then the word is
If no matching file names are found,
and the shell option
.B nullglob
-is disabled, the word is left unchanged.
+is not enabled, the word is left unchanged.
If the
.B nullglob
option is set, and no matches are found,
the word is removed.
+If the
+.B 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
.B nocaseglob
is enabled, the match is performed without regard to the case
for a description of the
.BR nocaseglob ,
.BR nullglob ,
+.BR failglob ,
and
.B dotglob
shell options.
.B ``.''
and
.B ``..''
-are always ignored, even when
+are always ignored when
.SM
.B GLOBIGNORE
-is set. However, setting
+is set and not null. However, setting
.SM
.B GLOBIGNORE
-has the effect of enabling the
+to a non-null value has the effect of enabling the
.B dotglob
shell option, so all other file names beginning with a
.B ``.''
.PP
Any character that appears in a pattern, other than the special pattern
characters described below, matches itself. The NUL character may not
-occur in a pattern. The special pattern characters must be quoted if
+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.
.PP
The special pattern characters have the following meanings:
.TP
.B *
Matches any string, including the null string.
+When the \fBglobstar\fP shell option is enabled, and \fB*\fP is used in
+a filename expansion context, two adjacent \fB*\fPs used as a single
+pattern will match all files and zero or more directories and
+subdirectories.
+If followed by a \fB/\fP, two adjacent \fB*\fPs will match only directories
+and subdirectories.
.TP
.B ?
Matches any single character.
.TP
.B [...]
Matches any one of the enclosed characters. A pair of characters
-separated by a minus sign denotes a
-.IR range ;
-any character lexically between those two characters, inclusive,
+separated by a hyphen denotes a
+\fIrange expression\fP;
+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
.B [
is a
or a
.B ^
then any character not enclosed is matched.
+The sorting order of characters in range expressions is determined by
+the current locale and the value of the \fBLC_COLLATE\fP shell variable,
+if set.
A
.B \-
may be matched by including it as the first or last character
.BR ] ,
\fIcharacter classes\fP can be specified using the syntax
\fB[:\fP\fIclass\fP\fB:]\fP, where \fIclass\fP is one of the
-following classes defined in the POSIX.2 standard:
+following classes defined in the POSIX standard:
.PP
.RS
.B
-.if n alnum alpha ascii blank cntrl digit graph lower print punct space upper xdigit
-.if t alnum alpha ascii blank cntrl digit graph lower print punct space upper xdigit
+.if n alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit
+.if t alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit
.br
A character class matches any character belonging to that class.
+The \fBword\fP character class matches letters, digits, and the character _.
.br
.if t .sp 0.5
.if n .sp 1
.PP
If the \fBextglob\fP shell option is enabled using the \fBshopt\fP
builtin, several extended pattern matching operators are recognized.
-In the following description, a \fIpattern\-list\fP is a list of one
+In the following description, a \fIpattern-list\fP is a list of one
or more patterns separated by a \fB|\fP.
Composite patterns may be formed using one or more of the following
sub-patterns:
Matches one or more occurrences of the given patterns
.TP
\fB@(\fP\^\fIpattern-list\^\fP\fB)\fP
-Matches exactly one of the given patterns
+Matches one of the given patterns
.TP
\fB!(\fP\^\fIpattern-list\^\fP\fB)\fP
Matches anything except one of the given patterns
After the preceding expansions, all unquoted occurrences of the
characters
.BR \e ,
-.BR ' ,
+.BR \(aq ,
and \^\f3"\fP\^ that did not result from one of the above
expansions are removed.
.SH REDIRECTION
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, and pathname expansion.
+expansion, quote removal, pathname expansion, and word splitting.
If it expands to more than one word,
.B bash
reports an error.
before the standard output was redirected to
.IR dirlist .
.PP
+\fBBash\fP handles several filenames specially when they are used in
+redirections, as described in the following table:
+.RS
+.PP
+.PD 0
+.TP
+.B /dev/fd/\fIfd\fP
+If \fIfd\fP is a valid integer, file descriptor \fIfd\fP is duplicated.
+.TP
+.B /dev/stdin
+File descriptor 0 is duplicated.
+.TP
+.B /dev/stdout
+File descriptor 1 is duplicated.
+.TP
+.B /dev/stderr
+File descriptor 2 is duplicated.
+.TP
+.B /dev/tcp/\fIhost\fP/\fIport\fP
+If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP
+is an integer port number or service name, \fBbash\fP attempts to open
+a TCP connection to the corresponding socket.
+.TP
+.B /dev/udp/\fIhost\fP/\fIport\fP
+If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP
+is an integer port number or service name, \fBbash\fP attempts to open
+a UDP connection to the corresponding socket.
+.PD
+.RE
+.PP
A failure to open or create a file causes the redirection to fail.
+.PP
+Redirections using file descriptors greater than 9 should be used with
+care, as they may conflict with file descriptors the shell uses
+internally.
.SS Redirecting Input
.PP
Redirection of input causes the file whose name results from
.B noclobber
option to the
.B set
-builtin has been enabled, the redirection will fail if the filename
+builtin has been enabled, the redirection will fail if the file
whose name results from the expansion of \fIword\fP exists and is
a regular file.
If the redirection operator is
.PP
.SS Redirecting Standard Output and Standard Error
.PP
-.B Bash
-allows both the
+This construct 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
-.I word
-with this construct.
+.IR word .
.PP
There are two formats for redirecting standard output and
standard error:
.PP
\fB>\fP\fIword\fP 2\fB>&\fP1
.RE
+.PP
+.SS Appending Standard Output and Standard Error
+.PP
+This construct allows both the
+standard output (file descriptor 1) and
+the standard error output (file descriptor 2)
+to be appended to the file whose name is the
+expansion of
+.IR word .
+.PP
+The format for appending standard output and standard error is:
+.RS
+.PP
+\fB&>>\fP\fIword\fP
+.RE
+.PP
+This is semantically equivalent to
+.RS
+.PP
+\fB>>\fP\fIword\fP 2\fB>&\fP1
+.RE
.SS Here Documents
.PP
This type of redirection instructs the shell to read input from the
current source until a line containing only
-.I word
+.I delimiter
(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.
.PP
-The format of here-documents is as follows:
+The format of here-documents is:
.RS
.PP
.nf
\fB<<\fP[\fB\-\fP]\fIword\fP
- \fIhere\-document\fP
+ \fIhere-document\fP
\fIdelimiter\fP
.fi
.RE
.PP
-No parameter expansion, command substitution, pathname
-expansion, or arithmetic expansion is performed on
+No parameter expansion, command substitution, arithmetic expansion,
+or pathname expansion is performed on
.IR word .
If any characters in
.I word
If \fIword\fP is unquoted,
all lines of the here-document are subjected to parameter expansion,
command substitution, and arithmetic expansion. In the latter
-case, the pair
+case, the character sequence
.B \e<newline>
is ignored, and
.B \e
.BR \e ,
.BR $ ,
and
-.BR ` .
+.BR \` .
.PP
If the redirection operator is
.BR <<\- ,
This allows
here-documents within shell scripts to be indented in a
natural fashion.
+.SS "Here Strings"
+A variant of here documents, the format is:
+.RS
+.PP
+.nf
+\fB<<<\fP\fIword\fP
+.fi
+.RE
+.PP
+The \fIword\fP is expanded and supplied to the command on its standard
+input.
.SS "Duplicating File Descriptors"
.PP
The redirection operator
As a special case, if \fIn\fP is omitted, and \fIword\fP does not
expand to one or more digits, the standard output and standard
error are redirected as described previously.
+.SS "Moving File Descriptors"
+.PP
+The redirection operator
+.RS
+.PP
+[\fIn\fP]\fB<&\fP\fIdigit\fP\fB\-\fP
+.RE
+.PP
+moves the file descriptor \fIdigit\fP to file descriptor
+.IR n ,
+or the standard input (file descriptor 0) if \fIn\fP is not specified.
+\fIdigit\fP is closed after being duplicated to \fIn\fP.
+.PP
+Similarly, the redirection operator
+.RS
+.PP
+[\fIn\fP]\fB>&\fP\fIdigit\fP\fB\-\fP
+.RE
+.PP
+moves the file descriptor \fIdigit\fP to file descriptor
+.IR n ,
+or the standard output (file descriptor 1) if \fIn\fP is not specified.
.SS "Opening File Descriptors for Reading and Writing"
.PP
The redirection operator
.I n
is not specified. If the file does not exist, it is created.
.SH ALIASES
-Aliases allow a string to be substituted for a word when it is used
+\fIAliases\fP 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
-.I aliases
-that may be set and unset with the
+The shell maintains a list of aliases that may be set and unset with the
.B alias
and
.B unalias
.SM
.B SHELL BUILTIN COMMANDS
below).
-The first word of each command, if unquoted,
+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 alias name and the replacement text may contain any valid
-shell input, including the
-.I metacharacters
-listed above, with the exception that the alias name may not
-contain \fI=\fP. The first word of the replacement text is tested
+The characters \fB/\fP, \fB$\fP, \fB\`\fP, and \fB=\fP and
+any of the shell \fImetacharacters\fP 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
+is not expanded a second time.
+This means that one may alias
.B ls
to
.BR "ls \-F" ,
command.
.PP
There is no mechanism for using arguments in the replacement text.
-If arguments are needed, a shell function should be used.
+If arguments are needed, a shell function should be used (see
+.SM
+.B FUNCTIONS
+below).
.PP
Aliases are not expanded when the shell is not interactive, unless
the
.SM
.BR "SHELL GRAMMAR" ,
stores a series of commands for later execution.
+When the name of a shell function is used as a simple command name,
+the list of commands associated with that function name is executed.
Functions are executed in the context of the
current shell; no new process is created to interpret
them (contrast this with the execution of a shell script).
When a function is executed, the arguments to the
function become the positional parameters
-during its execution. The special parameter
+during its execution.
+The special parameter
.B #
-is updated to reflect the change. Positional parameter 0
-is unchanged. All other aspects of the shell execution
+is updated to reflect the change. Special parameter 0
+is unchanged.
+The first element of the
+.SM
+.B 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
.SM
.B DEBUG
-trap (see the description of the
+and
+.B RETURN
+traps (see the description of the
.B trap
builtin under
.SM
.B SHELL BUILTIN COMMANDS
-below) is not inherited.
+below) are not inherited unless the function has been given the
+\fBtrace\fP attribute (see the description of the
+.SM
+.B declare
+builtin below) or the
+\fB\-o functrace\fP shell option has been enabled with
+the \fBset\fP builtin
+(in which case all functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps).
.PP
Variables local to the function may be declared with the
.B local
.B return
is executed in a function, the function completes and
execution resumes with the next command after the function
-call. When a function completes, the values of the
+call.
+Any command associated with the \fBRETURN\fP trap is executed
+before execution resumes.
+When a function completes, the values of the
positional parameters and the special parameter
.B #
are restored to the values they had prior to the function's
.B declare
or
.B typeset
-will list the function names only.
+will list the function names only
+(and optionally the source file and line number, if the \fBextdebug\fP
+shell option is enabled).
Functions may be exported so that subshells
automatically have them defined with the
.B \-f
option to the
.B export
builtin.
+A function definition may be deleted using the \fB\-f\fP option to
+the
+.B unset
+builtin.
+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.
.PP
Functions may be recursive. No limit is imposed on the number
of recursive calls.
.SH "ARITHMETIC EVALUATION"
The shell allows arithmetic expressions to be evaluated, under
-certain circumstances (see the \fBlet\fP builtin command and
-\fBArithmetic Expansion\fP).
-Evaluation is done in long integers with no check for overflow,
+certain circumstances (see the \fBlet\fP and \fBdeclare\fP builtin
+commands and \fBArithmetic Expansion\fP).
+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.
.PP
.PD 0
.TP
+.B \fIid\fP++ \fIid\fP\-\-
+variable post-increment and post-decrement
+.TP
+.B ++\fIid\fP \-\-\fIid\fP
+variable pre-increment and pre-decrement
+.TP
.B \- +
unary minus and plus
.TP
logical OR
.TP
.B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP
-conditional evaluation
+conditional operator
.TP
.B = *= /= %= += \-= <<= >>= &= ^= |=
assignment
+.TP
+.B \fIexpr1\fP , \fIexpr2\fP
+comma
.PD
.PP
Shell variables are allowed as operands; parameter expansion is
-performed before the expression is evaluated.
-The value of a parameter is coerced to a long integer within
-an expression. A shell variable need not have its integer attribute
+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
+\fIinteger\fP attribute using \fBdeclare -i\fP 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.
.PP
Constants with a leading 0 are interpreted as octal numbers.
Otherwise, numbers take the form [\fIbase#\fP]n, where \fIbase\fP
is a decimal number between 2 and 64 representing the arithmetic
base, and \fIn\fP is a number in that base.
-If \fIbase\fP is omitted, then base 10 is used.
+If \fIbase#\fP is omitted, then base 10 is used.
The digits greater than 9 are represented by the lowercase letters,
-the uppercase letters, _, and @, in that order.
+the uppercase letters, @, and _, in that order.
If \fIbase\fP is less than or equal to 36, lowercase and uppercase
-letters may be used interchangably to represent numbers between 10
+letters may be used interchangeably to represent numbers between 10
and 35.
.PP
Operators are evaluated in order of precedence. Sub-expressions in
and perform string and arithmetic comparisons.
Expressions are formed from the following unary or binary primaries.
If any \fIfile\fP argument to one of the primaries is of the form
-/dev/fd/\fIn\fP, then file descriptor \fIn\fP is checked.
+\fI/dev/fd/n\fP, then file descriptor \fIn\fP is checked.
+If the \fIfile\fP argument to one of the primaries is one of
+\fI/dev/stdin\fP, \fI/dev/stdout\fP, or \fI/dev/stderr\fP, file
+descriptor 0, 1, or 2, respectively, is checked.
+.PP
+Unless otherwise specified, primaries that operate on files follow symbolic
+links and operate on the target of the link, rather than the link itself.
.sp 1
.PD 0
.TP
.B \-g \fIfile\fP
True if \fIfile\fP exists and is set-group-id.
.TP
+.B \-h \fIfile\fP
+True if \fIfile\fP exists and is a symbolic link.
+.TP
.B \-k \fIfile\fP
True if \fIfile\fP exists and its ``sticky'' bit is set.
.TP
True if \fIfile\fP exists and has been modified since it was last read.
.TP
\fIfile1\fP \-\fBnt\fP \fIfile2\fP
-True if \fIfile1\fP is newer (according to
-modification date) than \fIfile2\fP.
+True if \fIfile1\fP is newer (according to modification date) than \fIfile2\fP,
+or if \fIfile1\fP exists and \fPfile2\fP does not.
.TP
\fIfile1\fP \-\fBot\fP \fIfile2\fP
-True if \fIfile1\fP is older than \fIfile2\fP.
+True if \fIfile1\fP is older than \fIfile2\fP, or if \fIfile2\fP exists
+and \fIfile1\fP does not.
.TP
\fIfile1\fP \fB\-ef\fP \fIfile2\fP
-True if \fIfile1\fP and \fIfile2\fP have the same device and
+True if \fIfile1\fP and \fIfile2\fP refer to the same device and
inode numbers.
.TP
.B \-o \fIoptname\fP
.B \-z \fIstring\fP
True if the length of \fIstring\fP is zero.
.TP
-.B \-n \fIstring\fP
-.TP
\fIstring\fP
+.PD 0
+.TP
+.B \-n \fIstring\fP
+.PD
True if the length of
.I string
is non-zero.
.TP
\fIstring1\fP \fB==\fP \fIstring2\fP
True if the strings are equal. \fB=\fP may be used in place of
-\fB==\fP.
+\fB==\fP for strict POSIX compliance.
.TP
\fIstring1\fP \fB!=\fP \fIstring2\fP
True if the strings are not equal.
.B PATH
for a directory containing an executable file by that name.
.B Bash
-uses a hash table to remember the full file names of executable
+uses a hash table to remember the full pathnames of executable
files (see
.B hash
under
.SM
.B PATH
is performed only if the command is not found in the hash table.
-If the search is unsuccessful, the shell prints an error
+If the search is unsuccessful, the shell searches for a defined shell
+function named \fBcommand_not_found_handle\fP.
+If that function exists, it is invoked with the original command and
+the original command's arguments as its arguments, and the function's
+exit status becomes the exit status of the shell.
+If that function is not defined, the shell prints an error
message and returns an exit status of 127.
.PP
If the search is successful, or if the command name contains
.IP \(bu
the file creation mode mask
.IP \(bu
-shell variables marked for export, along with variables exported for
-the command, passed in the environment
+shell variables and functions marked for export, along with variables
+exported for the command, passed in the environment
.IP \(bu
-traps caught by the shell are reset to the values the inherited
-from the shell's parent, and traps ignored by the shell are ignored
+traps caught by the shell are reset to the values inherited from the
+shell's parent, and traps ignored by the shell are ignored
.PP
A command invoked in this separate environment cannot affect the
shell's execution environment.
.PP
-Command substitution and asynchronous commands are invoked in a
+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.
+.PP
+Subshells spawned to execute command substitutions inherit the value of
+the \fB\-e\fP option from the parent shell. When not in posix mode,
+Bash clears the \fB\-e\fP option in such subshells.
+.PP
+If a command is followed by a \fB&\fP and job control is not active, the
+default standard input for the command is the empty file \fI/dev/null\fP.
+Otherwise, the invoked command inherits the file descriptors of the calling
+shell as modified by redirections.
.SH ENVIRONMENT
When a program is invoked it is given an array of strings
called the
\fIname\fP\-\fIvalue\fP pairs, of the form
.IR "name\fR=\fPvalue" .
.PP
-The shell allows you to manipulate the environment in several
-ways. On invocation, the shell scans its own environment and
+The shell provides several ways to manipulate the environment.
+On invocation, the shell scans its own environment and
creates a parameter for each name found, automatically marking
it for
.I export
is set to the full file name of the command and passed to that
command in its environment.
.SH "EXIT STATUS"
+.PP
+The exit status of an executed command is the value returned by the
+\fIwaitpid\fP system call or equivalent function. Exit statuses
+fall between 0 and 255, though, as explained below, the shell may
+use values above 125 specially. Exit statuses from shell builtins and
+compound commands are also limited to this range. Under certain
+circumstances, the shell will use special values to indicate specific
+failure modes.
+.PP
For the shell's purposes, a command which exits with a
zero exit status has succeeded. An exit status of zero
indicates success. A non-zero exit status indicates failure.
-When a command terminates on a fatal signal, \fBbash\fP uses
-the value of 128+\fBsignal\fP as the exit status.
+When a command terminates on a fatal signal \fIN\fP, \fBbash\fP uses
+the value of 128+\fIN\fP as the exit status.
.PP
If a command is not found, the child process created to
execute it returns a status of 127. If a command is found
.SM
.BR SIGTSTP .
.PP
-Synchronous jobs started by \fBbash\fP have signal handlers
+Non-builtin commands run by \fBbash\fP have signal handlers
set to the values inherited by the shell from its parent.
When job control is not in effect, asynchronous commands
ignore
and
.SM
.B SIGQUIT
-as well.
+in addition to these inherited handlers.
Commands run as a result of command substitution ignore the
keyboard-generated job control signals
.SM
The shell exits by default upon receipt of a
.SM
.BR SIGHUP .
-Before exiting, it resends the
+Before exiting, an interactive shell resends the
.SM
.B SIGHUP
to all jobs, running or stopped.
.B SIGHUP
to all jobs when an interactive login shell exits.
.PP
-When \fBbash\fP receives a signal for which a trap has been set while
-waiting for a command to complete, the trap will not be executed until
-the command completes.
+If \fBbash\fP 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 \fBbash\fP is waiting for an asynchronous command via the \fBwait\fP
builtin, the reception of a signal for which a trap has been set will
cause the \fBwait\fP builtin to return immediately with an exit status
abstraction as the basis for job control.
.PP
To facilitate the implementation of the user interface to job
-control, the system maintains the notion of a \fIcurrent terminal
+control, the operating system maintains the notion of a \fIcurrent terminal
process group ID\fP. Members of this process group (processes whose
process group ID is equal to the current terminal process group ID)
receive keyboard-generated signals such as
is running supports
job control,
.B bash
-allows you to use it.
+contains facilities to use it.
Typing the
.I suspend
character (typically
.BR ^Z ,
Control-Z) while a process is running
-causes that process to be stopped and returns you to
+causes that process to be stopped and returns control to
.BR bash .
Typing the
.I "delayed suspend"
There are a number of ways to refer to a job in the shell.
The character
.B %
-introduces a job name. Job number
+introduces a job specification (\fIjobspec\fP). Job number
.I n
may be referred to as
.BR %n .
.I "previous job"
may be referenced using
.BR %\- .
+If there is only a single job, \fB%+\fP and \fB%\-\fP can both be used
+to refer to that job.
In output pertaining to jobs (e.g., the output of the
.B jobs
command), the current job is always flagged with a
.BR + ,
and the previous job with a
.BR \- .
+A single % (with no accompanying job specification) also refers to the
+current job.
.PP
Simply naming a job can be used to bring it into the
foreground:
is enabled,
.B bash
reports such changes immediately.
+Any trap on
+.SM
+.B SIGCHLD
+is executed for each child that exits.
.PP
If an attempt to exit
.B bash
-is made while jobs are stopped, the shell prints a warning message. The
+is made while jobs are stopped (or, if the \fBcheckjobs\fP shell option has
+been enabled using the \fBshopt\fP builtin, running), the shell prints a
+warning message, and, if the \fBcheckjobs\fP option is enabled, lists the
+jobs and their statuses.
+The
.B jobs
-command may then be used to inspect their status.
+command may then be used to inspect their status.
If a second attempt to exit is made without an intervening command,
-the shell does not print another warning, and the stopped
+the shell does not print another warning, and any stopped
jobs are terminated.
.SH PROMPTING
When executing interactively,
.B \ed
the date in "Weekday Month Date" format (e.g., "Tue May 26")
.TP
+.B \eD{\fIformat\fP}
+the \fIformat\fP is passed to \fIstrftime\fP(3) and the result is inserted
+into the prompt string; an empty \fIformat\fP results in a locale-specific
+time representation. The braces are required
+.TP
.B \ee
an ASCII escape character (033)
.TP
.B \eH
the hostname
.TP
+.B \ej
+the number of jobs currently managed by the shell
+.TP
+.B \el
+the basename of the shell's terminal device name
+.TP
.B \en
newline
.TP
.B \e@
the current time in 12-hour am/pm format
.TP
+.B \eA
+the current time in 24-hour HH:MM format
+.TP
.B \eu
the username of the current user
.TP
the version of \fBbash\fP (e.g., 2.00)
.TP
.B \eV
-the release of \fBbash\fP, version + patchlevel (e.g., 2.00.0)
+the release of \fBbash\fP, version + patch level (e.g., 2.00.0)
.TP
.B \ew
-the current working directory
+the current working directory, with \fB$HOME\fP abbreviated with a tilde
+(uses the \fB$PROMPT_DIRTRIM\fP variable)
.TP
.B \eW
-the basename of the current working directory
+the basename of the current working directory, with \fB$HOME\fP
+abbreviated with a tilde
.TP
.B \e!
the history number of this command
below), while the command number is the position in the sequence
of commands executed during the current shell session.
After the string is decoded, it is expanded via
-parameter expansion, command substitution, arithmetic expansion,
-string expansion, and quote removal, subject to the value of the
+parameter expansion, command substitution, arithmetic
+expansion, and quote removal, subject to the value of the
.B promptvars
shell option (see the description of the
.B shopt
shell, unless the
.B \-\-noediting
option is given at shell invocation.
+Line editing is also used when using the \fB\-e\fP option to the
+\fBread\fP builtin.
By default, the line editing commands are similar to those of emacs.
A vi-style line editing interface is also available.
-To turn off line editing after the shell is running, use the
-.B +o emacs
+Line editing can be enabled at any time using the
+.B \-o emacs
or
-.B +o vi
+.B \-o vi
options to the
.B set
builtin (see
.SM
.B SHELL BUILTIN COMMANDS
below).
+To turn off line editing after the shell is running, use the
+.B +o emacs
+or
+.B +o vi
+options to the
+.B set
+builtin.
.SS "Readline Notation"
.PP
In this section, the emacs-style notation is used to denote
.IR SPACE ,
and
.IR TAB .
+.PP
In addition to command names, readline allows keys to be bound
to a string that is inserted when the key is pressed (a \fImacro\fP).
.SS "Readline Key Bindings"
it should be bound. The name may be specified in one of two ways:
as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP
prefixes, or as a key sequence.
+.PP
When using the form \fBkeyname\fP:\^\fIfunction\-name\fP or \fImacro\fP,
.I keyname
is the name of a key spelled out in English. For example:
.I C\-o
is bound to run the macro
expressed on the right hand side (that is, to insert the text
-.I "> output"
+.if t \f(CW> output\fP
+.if n ``> output''
into the line).
.PP
In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP,
above in that strings denoting
an entire key sequence may be specified by placing the sequence
within double quotes. Some GNU Emacs style key escapes can be
-used, as in the following example.
+used, as in the following example, but the symbolic character names
+are not recognized.
.sp
.RS
"\eC\-u": universal\-argument
and
.I "ESC [ 1 1 ~"
is bound to insert the text
-.BR "Function Key 1" .
+.if t \f(CWFunction Key 1\fP.
+.if n ``Function Key 1''.
+.PP
The full set of GNU Emacs style escape sequences is
.RS
.PD 0
.B \e"
literal "
.TP
-.B \e'
-literal '
+.B \e\(aq
+literal \(aq
.RE
.PD
.PP
vertical tab
.TP
.B \e\fInnn\fP
-the character whose ASCII code is the octal value \fInnn\fP
+the eight-bit character whose value is the octal value \fInnn\fP
(one to three digits)
.TP
-.B \ex\fInnn\fP
-the character whose ASCII code is the hexadecimal value \fInnn\fP
-(one to three digits)
+.B \ex\fIHH\fP
+the eight-bit character whose value is the hexadecimal value \fIHH\fP
+(one or two hex digits)
.RE
.PD
.PP
Unquoted text is assumed to be a function name.
In the macro body, the backslash escapes described above are expanded.
Backslash will quote any other character in the macro text,
-including " and '.
+including " and \(aq.
.PP
.B Bash
allows the current readline key bindings to be displayed or modified
Except where noted, readline variables can take the values
.B On
or
-.BR Off .
+.B Off
+(without regard to case).
+Unrecognized variable names are ignored.
+When a variable value is read, empty or null values, "on" (case-insensitive),
+and "1" are equivalent to \fBOn\fP. All other values are equivalent to
+\fBOff\fP.
The variables and their default values are:
.PP
.PD 0
\fBvisible\fP, readline uses a visible bell if one is available.
If set to \fBaudible\fP, readline attempts to ring the terminal's bell.
.TP
+.B bind\-tty\-special\-chars (On)
+If set to \fBOn\fP, readline attempts to bind the control characters
+treated specially by the kernel's terminal driver to their readline
+equivalents.
+.TP
.B comment\-begin (``#'')
-The string that is inserted when the
-.B readline
+The string that is inserted when the readline
.B insert\-comment
command is executed.
This command is bound to
If set to \fBOn\fP, readline performs filename matching and completion
in a case\-insensitive fashion.
.TP
+.B completion\-prefix\-display\-length (0)
+The length in characters of the common prefix of a list of possible
+completions that is displayed without modification. When set to a
+value greater than zero, common prefixes longer than this value are
+replaced with an ellipsis when displaying possible completions.
+.TP
.B completion\-query\-items (100)
This determines when the user is queried about viewing
the number of possible completions
.B convert\-meta (On)
If set to \fBOn\fP, readline will convert characters with the
eighth bit set to an ASCII key sequence
-by stripping the eighth bit and prepending an
+by stripping the eighth bit and prefixing an
escape character (in effect, using escape as the \fImeta prefix\fP).
.TP
.B disable\-completion (Off)
If set to \fBon\fP, tilde expansion is performed when readline
attempts word completion.
.TP
+.B history\-preserve\-point (Off)
+If set to \fBon\fP, the history code attempts to place point at the
+same location on each history line retrieved with \fBprevious-history\fP
+or \fBnext-history\fP.
+.TP
+.B history\-size (0)
+Set the maximum number of history entries saved in the history list. If
+set to zero, the number of entries in the history list is not limited.
+.TP
.B horizontal\-scroll\-mode (Off)
When set to \fBOn\fP, makes readline use a single line for display,
scrolling the input horizontally on a single screen line when it
.B meta\-flag
is a synonym for this variable.
.TP
+.B isearch\-terminators (``C\-[C\-J'')
+The string of characters that should terminate an incremental
+search without subsequently executing the character as a command.
+If this variable has not been given a value, the characters
+\fIESC\fP and \fIC\-J\fP will terminate an incremental search.
+.TP
.B keymap (emacs)
Set the current readline keymap. The set of valid keymap names is
\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi,
If set to \fBOn\fP, history lines that have been modified are displayed
with a preceding asterisk (\fB*\fP).
.TP
+.B mark\-symlinked\-directories (Off)
+If set to \fBOn\fP, completed names which are symbolic links to directories
+have a slash appended (subject to the value of
+\fBmark\-directories\fP).
+.TP
+.B match\-hidden\-files (On)
+This variable, when set to \fBOn\fP, causes readline to match files whose
+names begin with a `.' (hidden files) when performing filename
+completion, unless the leading `.' is
+supplied by the user in the filename to be completed.
+.TP
.B output\-meta (Off)
If set to \fBOn\fP, readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence.
.TP
+.B page\-completions (On)
+If set to \fBOn\fP, readline uses an internal \fImore\fP-like pager
+to display a screenful of possible completions at a time.
+.TP
.B print\-completions\-horizontally (Off)
If set to \fBOn\fP, readline will display completions with matches
sorted horizontally in alphabetical order, rather than down the screen.
+.TP
+.B revert\-all\-at\-newline (Off)
+If set to \fBon\fP, readline will undo all changes to history lines
+before returning when \fBaccept\-line\fP is executed. By default,
+history lines may be modified and retain individual undo lists across
+calls to \fBreadline\fP.
.TP
.B show\-all\-if\-ambiguous (Off)
This alters the default behavior of the completion functions. If
words which have more than one possible completion cause the
matches to be listed immediately instead of ringing the bell.
.TP
+.B show\-all\-if\-unmodified (Off)
+This alters the default behavior of the completion functions in
+a fashion similar to \fBshow\-all\-if\-ambiguous\fP.
+If set to
+.BR on ,
+words which have more than one possible completion without any
+possible partial completion (the possible completions don't share
+a common prefix) cause the matches to be listed immediately instead
+of ringing the bell.
+.TP
.B visible\-stats (Off)
If set to \fBOn\fP, a character denoting a file's type as reported
by \fIstat\fP(2) is appended to the filename when listing possible
the next entry from the history matching the string typed so far.
An incremental search requires only as many characters as needed to
find the desired history entry.
-The Escape character is used to terminate an incremental search.
-Control-J will also terminate the search.
+The characters present in the value of the \fBisearch-terminators\fP
+variable are used to terminate an incremental search.
+If that variable has not been assigned a value the Escape and
+Control-J characters will terminate an incremental search.
Control-G will abort an incremental search and restore the original
line.
When the search is terminated, the history entry containing the
search string becomes the current line.
+.PP
To find other matching entries in the history list, type Control-S or
Control-R as appropriate.
This will search backward or forward in the history for the next
For instance, a \fInewline\fP will terminate the search and accept
the line, thereby executing the command from the history list.
.PP
+Readline remembers the last incremental search string. If two
+Control-Rs are typed without any intervening characters defining a
+new search string, any remembered search string is used.
+.PP
Non-incremental searches read the entire search string before starting
to search for matching history lines. The search string may be
typed by the user or be part of the contents of the current line.
The following is a list of the names of the commands and the default
key sequences to which they are bound.
Command names without an accompanying key sequence are unbound by default.
+In the following descriptions, \fIpoint\fP refers to the current cursor
+position, and \fImark\fP refers to a cursor position saved by the
+\fBset\-mark\fP command.
+The text between the point and mark is referred to as the \fIregion\fP.
.SS Commands for Moving
.PP
.PD 0
alphanumeric characters (letters and digits).
.TP
.B backward\-word (M\-b)
-Move back to the start of this, or the previous, word. Words are
-composed of alphanumeric characters (letters and digits).
+Move back to the start of the current or previous word.
+Words are composed of alphanumeric characters (letters and digits).
+.TP
+.B shell\-forward\-word
+Move forward to the end of the next word.
+Words are delimited by non-quoted shell metacharacters.
+.TP
+.B shell\-backward\-word
+Move back to the start of the current or previous word.
+Words are delimited by non-quoted shell metacharacters.
.TP
.B clear\-screen (C\-l)
Clear the screen leaving the current line at the top of the screen.
.TP
.B history\-search\-forward
Search forward through the history for the string of characters
-between the start of the current line and the current cursor
-position (the \fIpoint\fP).
+between the start of the current line and the point.
This is a non-incremental search.
.TP
.B history\-search\-backward
.TP
.B yank\-nth\-arg (M\-C\-y)
Insert the first argument to the previous command (usually
-the second word on the previous line) at point (the current
-cursor position). With an argument
+the second word on the previous line) at point.
+With an argument
.IR n ,
insert the \fIn\fPth word from the previous command (the words
in the previous command begin with word 0). A negative argument
inserts the \fIn\fPth word from the end of the previous command.
+Once the argument \fIn\fP is computed, the argument is extracted
+as if the "!\fIn\fP" history expansion had been specified.
.TP
.B
yank\-last\-arg (M\-.\^, M\-_\^)
behave exactly like \fByank\-nth\-arg\fP.
Successive calls to \fByank\-last\-arg\fP move back through the history
list, inserting the last argument of each line in turn.
+The history expansion facilities are used to extract the last argument,
+as if the "!$" history expansion had been specified.
.TP
.B shell\-expand\-line (M\-C\-e)
Expand the line as the shell does. This
Accept the current line for execution and fetch the next line
relative to the current line from the history for editing. Any
argument is ignored.
+.TP
+.B edit\-and\-execute\-command (C\-xC\-e)
+Invoke an editor on the current command line, and execute the result as shell
+commands.
+\fBBash\fP attempts to invoke
+.SM
+.BR $VISUAL ,
+.SM
+.BR $EDITOR ,
+and \fIemacs\fP as the editor, in that order.
.PD
.SS Commands for Changing Text
.PP
.PD 0
.TP
.B delete\-char (C\-d)
-Delete the character under the cursor. If point is at the
+Delete the character at point. If point is at the
beginning of the line, there are no characters in the line, and
the last character typed was not bound to \fBdelete\-char\fP,
then return
Delete the character behind the cursor. When given a numeric argument,
save the deleted text on the kill ring.
.TP
+.B forward\-backward\-delete\-char
+Delete the character under the cursor, unless the cursor is at the
+end of the line, in which case the character behind the cursor is
+deleted.
+.TP
.B quoted\-insert (C\-q, C\-v)
Add the next character typed to the line verbatim. This is
how to insert characters like \fBC\-q\fP, for example.
Insert the character typed.
.TP
.B transpose\-chars (C\-t)
-Drag the character before point forward over the character at point.
-Point moves forward as well. If point is at the end of the line, then
-transpose the two characters before point. Negative arguments don't work.
+Drag the character before point forward over the character at point,
+moving point forward as well.
+If point is at the end of the line, then this transposes
+the two characters before point.
+Negative arguments have no effect.
.TP
.B transpose\-words (M\-t)
-Drag the word behind the cursor past the word in front of the cursor
-moving the cursor over that word as well.
+Drag the word before point past the word after point,
+moving point over that word as well.
+If point is at the end of the line, this transposes
+the last two words on the line.
.TP
.B upcase\-word (M\-u)
Uppercase the current (or following) word. With a negative argument,
.B capitalize\-word (M\-c)
Capitalize the current (or following) word. With a negative argument,
capitalize the previous word, but do not move point.
+.TP
+.B overwrite\-mode
+Toggle overwrite mode. With an explicit positive numeric argument,
+switches to overwrite mode. With an explicit non-positive numeric
+argument, switches to insert mode. This command affects only
+\fBemacs\fP mode; \fBvi\fP mode does overwrite differently.
+Each call to \fIreadline()\fP starts in insert mode.
+In overwrite mode, characters bound to \fBself\-insert\fP replace
+the text at point rather than pushing the text to the right.
+Characters bound to \fBbackward\-delete\-char\fP replace the character
+before point with a space. By default, this command is unbound.
.PD
.SS Killing and Yanking
.PP
.PD 0
.TP
.B kill\-line (C\-k)
-Kill the text from the current cursor position to the end of the line.
+Kill the text from point to the end of the line.
.TP
.B backward\-kill\-line (C\-x Rubout)
Kill backward to the beginning of the line.
.B unix\-line\-discard (C\-u)
Kill backward from point to the beginning of the line.
The killed text is saved on the kill-ring.
-\" There is no real difference between this and backward-kill-line
+.\" There is no real difference between this and backward-kill-line
.TP
.B kill\-whole\-line
-Kill all characters on the current line, no matter where the
-cursor is.
+Kill all characters on the current line, no matter where point is.
.TP
.B kill\-word (M\-d)
-Kill from the cursor to the end of the current word, or if between
-words, to the end of the next word. Word boundaries are the same as
-those used by \fBforward\-word\fP.
+Kill from point to the end of the current word, or if between
+words, to the end of the next word.
+Word boundaries are the same as those used by \fBforward\-word\fP.
.TP
.B backward\-kill\-word (M\-Rubout)
-Kill the word behind the cursor. Word boundaries are the same as
-those used by \fBbackward\-word\fP.
+Kill the word behind point.
+Word boundaries are the same as those used by \fBbackward\-word\fP.
+.TP
+.B shell\-kill\-word (M\-d)
+Kill from point to the end of the current word, or if between
+words, to the end of the next word.
+Word boundaries are the same as those used by \fBshell\-forward\-word\fP.
+.TP
+.B shell\-backward\-kill\-word (M\-Rubout)
+Kill the word behind point.
+Word boundaries are the same as those used by \fBshell\-backward\-word\fP.
.TP
.B unix\-word\-rubout (C\-w)
-Kill the word behind the cursor, using white space as a word boundary.
-The word boundaries are different from \fBbackward\-kill\-word\fP.
+Kill the word behind point, using white space as a word boundary.
+The killed text is saved on the kill-ring.
+.TP
+.B unix\-filename\-rubout
+Kill the word behind point, using white space and the slash character
+as the word boundaries.
+The killed text is saved on the kill-ring.
.TP
.B delete\-horizontal\-space (M\-\e)
Delete all spaces and tabs around point.
.TP
.B kill\-region
-Kill the text between the point and \fImark\fP (saved cursor position).
-This text is referred to as the \fIregion\fP.
+Kill the text in the current region.
.TP
.B copy\-region\-as\-kill
Copy the text in the region to the kill buffer.
The word boundaries are the same as \fBforward\-word\fP.
.TP
.B yank (C\-y)
-Yank the top of the kill ring into the buffer at the cursor.
+Yank the top of the kill ring into the buffer at point.
.TP
.B yank\-pop (M\-y)
Rotate the kill ring, and yank the new top. Only works following
with a single match from the list of possible completions.
Repeated execution of \fBmenu\-complete\fP steps through the list
of possible completions, inserting each match in turn.
-At the end of the list of completions, the bell is rung and the
-original text is restored.
+At the end of the list of completions, the bell is rung
+(subject to the setting of \fBbell\-style\fP)
+and the original text is restored.
An argument of \fIn\fP moves \fIn\fP positions forward in the list
of matches; a negative argument may be used to move backward
through the list.
This command is intended to be bound to \fBTAB\fP, but is unbound
by default.
.TP
+.B delete\-char\-or\-list
+Deletes the character under the cursor if not at the beginning or
+end of the line (like \fBdelete\-char\fP).
+If at the end of the line, behaves identically to
+\fBpossible\-completions\fP.
+This command is unbound by default.
+.TP
.B complete\-filename (M\-/)
Attempt filename completion on the text before point.
.TP
the text against lines from the history list for possible
completion matches.
.TP
+.B dabbrev\-expand
+Attempt menu completion on the text before point, comparing
+the text against lines from the history list for possible
+completion matches.
+.TP
.B complete\-into\-braces (M\-{)
-Perform filename completion and return the list of possible completions
+Perform filename completion and insert the list of possible completions
enclosed within braces so the list is available to the shell (see
.B Brace Expansion
above).
.B undo
command enough times to return the line to its initial state.
.TP
-.B tilde\-expand (M\-~)
+.B tilde\-expand (M\-&)
Perform tilde expansion on the current word.
.TP
.B set\-mark (C\-@, M\-<space>)
-Set the mark to the current point. If a
+Set the mark to the point. If a
numeric argument is supplied, the mark is set to that position.
.TP
.B exchange\-point\-and\-mark (C\-x C\-x)
character. A negative count searches for subsequent occurrences.
.TP
.B insert\-comment (M\-#)
-The value of the
-.B readline
+Without a numeric argument, the value of the readline
.B comment\-begin
-variable is inserted at the beginning of the current line, and the line
-is accepted as if a newline had been typed. This makes the current line
+variable is inserted at the beginning of the current line.
+If a numeric argument is supplied, this command acts as a toggle: if
+the characters at the beginning of the line do not match the value
+of \fBcomment\-begin\fP, the value is inserted, otherwise
+the characters in \fBcomment-begin\fP are deleted from the beginning of
+the line.
+In either case, the line is accepted as if a newline had been typed.
+The default value of
+\fBcomment\-begin\fP causes this command to make the current line
a shell comment.
+If a numeric argument causes the comment character to be removed, the line
+will be executed by the shell.
+.TP
+.B glob\-complete\-word (M\-g)
+The word before point is treated as a pattern for pathname expansion,
+with an asterisk implicitly appended. This pattern is used to
+generate a list of matching file names for possible completions.
.TP
.B glob\-expand\-word (C\-x *)
The word before point is treated as a pattern for pathname expansion,
and the list of matching file names is inserted, replacing the word.
+If a numeric argument is supplied, an asterisk is appended before
+pathname expansion.
.TP
.B glob\-list\-expansions (C\-x g)
The list of expansions that would have been generated by
.B glob\-expand\-word
is displayed, and the line is redrawn.
+If a numeric argument is supplied, an asterisk is appended before
+pathname expansion.
.TP
.B dump\-functions
Print all of the functions and their key bindings to the
.TP
.B dump\-macros
Print all of the readline key sequences bound to macros and the
-strings they ouput. If a numeric argument is supplied,
+strings they output. If a numeric argument is supplied,
the output is formatted in such a way that it can be made part
of an \fIinputrc\fP file.
.TP
Display version information about the current instance of
.BR bash .
.PD
+.SS Programmable Completion
+.PP
+When word completion is attempted for an argument to a command for
+which a completion specification (a \fIcompspec\fP) has been defined
+using the \fBcomplete\fP builtin (see
+.SM
+.B "SHELL BUILTIN COMMANDS"
+below), the programmable completion facilities are invoked.
+.PP
+First, the command name is identified.
+If a compspec has been defined for that command, the
+compspec is used to generate the list of possible completions for the word.
+If the command word is a full pathname, a compspec for the full
+pathname is searched for first.
+If no compspec is found for the full pathname, an attempt is made to
+find a compspec for the portion following the final slash.
+.PP
+Once a compspec has been found, it is used to generate the list of
+matching words.
+If a compspec is not found, the default \fBbash\fP completion as
+described above under \fBCompleting\fP is performed.
+.PP
+First, the actions specified by the compspec are used.
+Only matches which are prefixed by the word being completed are
+returned.
+When the
+.B \-f
+or
+.B \-d
+option is used for filename or directory name completion, the shell
+variable
+.SM
+.B FIGNORE
+is used to filter the matches.
+.PP
+Any completions specified by a filename expansion pattern to the
+\fB\-G\fP option are generated next.
+The words generated by the pattern need not match the word
+being completed.
+The
+.SM
+.B GLOBIGNORE
+shell variable is not used to filter the matches, but the
+.SM
+.B FIGNORE
+variable is used.
+.PP
+Next, the string specified as the argument to the \fB\-W\fP option
+is considered.
+The string is first split using the characters in the
+.SM
+.B IFS
+special variable as delimiters.
+Shell quoting is honored.
+Each word is then expanded using
+brace expansion, tilde expansion, parameter and variable expansion,
+command substitution, and arithmetic expansion,
+as described above under
+.SM
+.BR EXPANSION .
+The results are split using the rules described above under
+\fBWord Splitting\fP.
+The results of the expansion are prefix-matched against the word being
+completed, and the matching words become the possible completions.
+.PP
+After these matches have been generated, any shell function or command
+specified with the \fB\-F\fP and \fB\-C\fP options is invoked.
+When the command or function is invoked, the
+.SM
+.BR COMP_LINE ,
+.SM
+.BR COMP_POINT ,
+.SM
+.BR COMP_KEY ,
+and
+.SM
+.B COMP_TYPE
+variables are assigned values as described above under
+\fBShell Variables\fP.
+If a shell function is being invoked, the
+.SM
+.B COMP_WORDS
+and
+.SM
+.B COMP_CWORD
+variables are also set.
+When the function or command is invoked, the first argument is the
+name of the command whose arguments are being completed, the
+second argument is the word being completed, and the third argument
+is the word preceding the word being completed on the current command line.
+No filtering of the generated completions against the word being completed
+is performed; the function or command has complete freedom in generating
+the matches.
+.PP
+Any function specified with \fB\-F\fP is invoked first.
+The function may use any of the shell facilities, including the
+\fBcompgen\fP builtin described below, to generate the matches.
+It must put the possible completions in the
+.SM
+.B COMPREPLY
+array variable.
+.PP
+Next, any command specified with the \fB\-C\fP option is invoked
+in an environment equivalent to command substitution.
+It should print a list of completions, one per line, to the
+standard output.
+Backslash may be used to escape a newline, if necessary.
+.PP
+After all of the possible completions are generated, any filter
+specified with the \fB\-X\fP option is applied to the list.
+The filter is a pattern as used for pathname expansion; a \fB&\fP
+in the pattern is replaced with the text of the word being completed.
+A literal \fB&\fP may be escaped with a backslash; the backslash
+is removed before attempting a match.
+Any completion that matches the pattern will be removed from the list.
+A leading \fB!\fP negates the pattern; in this case any completion
+not matching the pattern will be removed.
+.PP
+Finally, any prefix and suffix specified with the \fB\-P\fP and \fB\-S\fP
+options are added to each member of the completion list, and the result is
+returned to the readline completion code as the list of possible
+completions.
+.PP
+If the previously-applied actions do not generate any matches, and the
+\fB\-o dirnames\fP option was supplied to \fBcomplete\fP when the
+compspec was defined, directory name completion is attempted.
+.PP
+If the \fB\-o plusdirs\fP option was supplied to \fBcomplete\fP when the
+compspec was defined, directory name completion is attempted and any
+matches are added to the results of the other actions.
+.PP
+By default, if a compspec is found, whatever it generates is returned
+to the completion code as the full set of possible completions.
+The default \fBbash\fP completions are not attempted, and the readline
+default of filename completion is disabled.
+If the \fB\-o bashdefault\fP option was supplied to \fBcomplete\fP when
+the compspec was defined, the \fBbash\fP default completions are attempted
+if the compspec generates no matches.
+If the \fB\-o default\fP option was supplied to \fBcomplete\fP when the
+compspec was defined, readline's default completion will be performed
+if the compspec (and, if attempted, the default \fBbash\fP completions)
+generate no matches.
+.PP
+When a compspec indicates that directory name completion is desired,
+the programmable completion functions force readline to append a slash
+to completed names which are symbolic links to directories, subject to
+the value of the \fBmark\-directories\fP readline variable, regardless
+of the setting of the \fBmark-symlinked\-directories\fP readline variable.
.SH HISTORY
When the
.B \-o history
.B set
builtin is enabled, the shell provides access to the
\fIcommand history\fP,
-the list of commands previously typed. The text of the last
+the list of commands previously typed.
+The value of the \fBHISTSIZE\fP variable is used as the
+number of commands to save in a history list.
+The text of the last
.SM
.B HISTSIZE
-commands (default 500) is saved in a history list. The shell
+commands (default 500) is saved. The shell
stores each command in the history list prior to parameter and
variable expansion (see
.SM
and
.SM
.BR HISTCONTROL .
+.PP
On startup, the history is initialized from the file named by
the variable
.SM
.B HISTFILE
(default \fI~/.bash_history\fP).
+The file named by the value of
.SM
.B HISTFILE
is truncated, if necessary, to contain no more than
+the number of lines specified by the value of
.SM
-.B HISTFILESIZE
-lines.
+.BR HISTFILESIZE .
+When the history file is read,
+lines beginning with the history comment character followed immediately
+by a digit are interpreted as timestamps for the preceding history line.
+These timestamps are optionally displayed depending on the value of the
+.SM
+.B HISTTIMEFORMAT
+variable.
When an interactive shell exits, the last
.SM
-.B HISTSIZE
+.B $HISTSIZE
lines are copied from the history list to
.SM
-.BR HISTFILE .
+.BR $HISTFILE .
If the
.B histappend
shell option is enabled
.SM
.B HISTFILE
is unset, or if the history file is unwritable, the history is
-not saved. After saving the history, the history file is truncated
+not saved.
+If the
+.SM
+.HISTTIMEFORMAT
+variable is set, time stamps are written to the history file, marked
+with the history comment character, so
+they may be preserved across shell sessions.
+This uses the history comment character to distinguish timestamps from
+other history lines.
+After saving the history, the history file is truncated
to contain no more than
.SM
.B HISTFILESIZE
the history list.
The
.B history
-builtin can be used to display or modify the history list and
+builtin may be used to display or modify the history list and
manipulate the history file.
-When using the command-line editing, search commands
+When using command-line editing, search commands
are available in each editing mode that provide access to the
history list.
.PP
Only backslash (\^\fB\e\fP\^) and single quotes can quote
the history expansion character.
.PP
+Several characters inhibit history expansion if found immediately
+following the history expansion character, even if it is unquoted:
+space, tab, newline, carriage return, and \fB=\fP.
+If the \fBextglob\fP shell option is enabled, \fB(\fP will also
+inhibit expansion.
+.PP
Several shell options settable with the
.B shopt
builtin may be used to tailor the behavior of history expansion.
.B histchars
above under
.BR "Shell Variables" ).
+The shell uses
+the history comment character to mark history timestamps when
+writing the history file.
.SS Event Designators
.PP
An event designator is a reference to a command line entry in the
.B !
Start a history substitution, except when followed by a
.BR blank ,
-newline, = or (.
+newline, carriage return, =
+or ( (when the \fBextglob\fP shell option is enabled using
+the \fBshopt\fP builtin).
.TP
.B !\fIn\fR
Refer to command line
`\fB:s\fP', any delimiter can be used
in place of /, and the final delimiter is optional
if it is the last character of the event line.
+An \fBa\fP may be used as a synonym for \fBg\fP.
+.TP
+.B G
+Apply the following `\fBs\fP' modifier once to each word in the event line.
.PD
.SH "SHELL BUILTIN COMMANDS"
.\" start of bash_builtins
accepts
.B \-\-
to signify the end of the options.
+For example, the \fB:\fP, \fBtrue\fP, \fBfalse\fP, and \fBtest\fP builtins
+do not accept options.
.sp .5
.PD 0
.TP
and performing any specified
redirections. A zero exit code is returned.
.TP
-.PD 0
\fB .\| \fP \fIfilename\fP [\fIarguments\fP]
+.PD 0
.TP
\fBsource\fP \fIfilename\fP [\fIarguments\fP]
.PD
The file searched for in
.SM
.B PATH
-need not be executable. The current directory is
+need not be executable.
+When \fBbash\fP is not in \fIposix mode\fP, the current directory is
searched if no file is found in
.SM
.BR PATH .
\fBAlias\fP returns true unless a \fIname\fP is given for which
no alias has been defined.
.TP
-\fBbg\fP [\fIjobspec\fP]
-Resume the suspended job \fIjobspec\fP in the background, as if it
+\fBbg\fP [\fIjobspec\fP ...]
+Resume each suspended job \fIjobspec\fP in the background, as if it
had been started with
.BR & .
-If \fIjobspec\fP is not present, the shell's notion of the
-\fIcurrent job\fP is used.
+If
+.I jobspec
+is not present, the shell's notion of the \fIcurrent job\fP is used.
.B bg
.I jobspec
returns 0 unless run when job control is disabled or, when run with
-job control enabled, if \fIjobspec\fP was not found or started without
-job control.
+job control enabled, any specified \fIjobspec\fP was not found
+or was started without job control.
.TP
-.PD 0
\fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-lpsvPSV\fP]
+.PD 0
.TP
\fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-q\fP \fIfunction\fP] [\fB\-u\fP \fIfunction\fP] [\fB\-r\fP \fIkeyseq\fP]
.TP
\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-f\fP \fIfilename\fP
.TP
+\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-x\fP \fIkeyseq\fP:\fIshell\-command\fP
+.TP
\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIfunction\-name\fP
+.TP
+\fBbind\fP \fIreadline\-command\fP
.PD
Display current
.B readline
-key and function bindings, or bind a key sequence to a
+key and function bindings, bind a key sequence to a
+.B readline
+function or macro, or set a
.B readline
-function or macro. The binding syntax accepted is identical to that of
+variable.
+Each non-option argument is a command as it would appear in
.IR .inputrc ,
-but each binding must be passed as a separate argument;
-e.g., '"\eC\-x\eC\-r": re\-read\-init\-file'. Options, if supplied, have the
-following meanings:
+but each binding or command must be passed as a separate argument;
+e.g., '"\eC\-x\eC\-r": re\-read\-init\-file'.
+Options, if supplied, have the following meanings:
.RS
.PD 0
.TP
.I keymap
names are
\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi,
-vi\-command\fP, and
+vi\-move, vi\-command\fP, and
.IR vi\-insert .
\fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is
equivalent to \fIemacs\-standard\fP.
.B \-P
List current \fBreadline\fP function names and bindings.
.TP
-.B \-v
-Display \fBreadline\fP variable names and values in such a way that they
-can be re-read.
-.TP
-.B \-V
-List current \fBreadline\fP variable names and values.
-.TP
.B \-s
Display \fBreadline\fP key sequences bound to macros and the strings
they output in such a way that they can be re-read.
Display \fBreadline\fP key sequences bound to macros and the strings
they output.
.TP
+.B \-v
+Display \fBreadline\fP variable names and values in such a way that they
+can be re-read.
+.TP
+.B \-V
+List current \fBreadline\fP variable names and values.
+.TP
.B \-f \fIfilename\fP
Read key bindings from \fIfilename\fP.
.TP
.TP
.B \-r \fIkeyseq\fP
Remove any current binding for \fIkeyseq\fP.
+.TP
+.B \-x \fIkeyseq\fP:\fIshell\-command\fP
+Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is
+entered.
+When \fIshell\-command\fP is executed, the shell sets the
+.B READLINE_LINE
+variable to the contents of the \fBreadline\fP line buffer and the
+.B READLINE_POINT
+variable to the current location of the insertion point.
+If the executed command changes the value of
+.B READLINE_LINE
+or
+.BR READLINE_POINT ,
+those new values will be reflected in the editing state.
.PD
.PP
The return value is 0 unless an unrecognized option is given or an
must be \(>= 1. If
.I n
is greater than the number of enclosing loops, all enclosing loops
-are exited. The return value is 0 unless the shell is not executing
-a loop when
-.B break
-is executed.
+are exited.
+The return value is 0 unless \fIn\fP is not greater than or equal to 1.
.TP
\fBbuiltin\fP \fIshell\-builtin\fP [\fIarguments\fP]
Execute the specified shell builtin, passing it
.I shell\-builtin
is not a shell builtin command.
.TP
-\fBcd\fP [\fB\-LP\fP] [\fIdir\fP]
+\fBcaller\fP [\fIexpr\fP]
+Returns the context of any active subroutine call (a shell function or
+a script executed with the \fB.\fP or \fBsource\fP builtins.
+Without \fIexpr\fP, \fBcaller\fP displays the line number and source
+filename of the current subroutine call.
+If a non-negative integer is supplied as \fIexpr\fP, \fBcaller\fP
+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 \fIexpr\fP does not correspond to a valid position in the
+call stack.
+.TP
+\fBcd\fP [\fB\-L|-P\fP] [\fIdir\fP]
Change the current directory to \fIdir\fP. The variable
.SM
.B HOME
is equivalent to
.SM
.BR $OLDPWD .
+If a non-empty directory name from \fBCDPATH\fP is used, or if
+\fB\-\fP is the first argument, and the directory change is
+successful, the absolute pathname of the new working directory is
+written to the standard output.
The return value is true if the directory was successfully changed;
false otherwise.
.TP
builtin is the exit status of
.IR command .
.TP
+\fBcompgen\fP [\fIoption\fP] [\fIword\fP]
+Generate possible completion matches for \fIword\fP according to
+the \fIoption\fPs, which may be any option accepted by the
+.B complete
+builtin with the exception of \fB\-p\fP and \fB\-r\fP, and write
+the matches to the standard output.
+When using the \fB\-F\fP or \fB\-C\fP options, the various shell variables
+set by the programmable completion facilities, while available, will not
+have useful values.
+.sp 1
+The matches will be generated in the same way as if the programmable
+completion code had generated them directly from a completion specification
+with the same flags.
+If \fIword\fP is specified, only those completions matching \fIword\fP
+will be displayed.
+.sp 1
+The return value is true unless an invalid option is supplied, or no
+matches were generated.
+.TP
+\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-E\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP]
+.br
+[\fB\-X\fP \fIfilterpat\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] \fIname\fP [\fIname ...\fP]
+.PD 0
+.TP
+\fBcomplete\fP \fB\-pr\fP [\fB\-E\fP] [\fIname\fP ...]
+.PD
+Specify how arguments to each \fIname\fP should be completed.
+If the \fB\-p\fP option is supplied, or if no options are supplied,
+existing completion specifications are printed in a way that allows
+them to be reused as input.
+The \fB\-r\fP option removes a completion specification for
+each \fIname\fP, or, if no \fIname\fPs are supplied, all
+completion specifications.
+The \fB\-E\fP option indicates that the remaining options and actions should
+apply to ``empty'' command completion; that is, completion attempted on a
+blank line.
+.sp 1
+The process of applying these completion specifications when word completion
+is attempted is described above under \fBProgrammable Completion\fP.
+.sp 1
+Other options, if specified, have the following meanings.
+The arguments to the \fB\-G\fP, \fB\-W\fP, and \fB\-X\fP options
+(and, if necessary, the \fB\-P\fP and \fB\-S\fP options)
+should be quoted to protect them from expansion before the
+.B complete
+builtin is invoked.
+.RS
+.PD 0
+.TP 8
+\fB\-o\fP \fIcomp-option\fP
+The \fIcomp-option\fP controls several aspects of the compspec's behavior
+beyond the simple generation of completions.
+\fIcomp-option\fP may be one of:
+.RS
+.TP 8
+.B bashdefault
+Perform the rest of the default \fBbash\fP completions if the compspec
+generates no matches.
+.TP 8
+.B default
+Use readline's default filename completion if the compspec generates
+no matches.
+.TP 8
+.B dirnames
+Perform directory name completion if the compspec generates no matches.
+.TP 8
+.B filenames
+Tell readline that the compspec generates filenames, so it can perform any
+filename\-specific processing (like adding a slash to directory names,
+quoting special characters, or suppressing trailing spaces).
+Intended to be used with shell functions.
+.TP 8
+.B nospace
+Tell readline not to append a space (the default) to words completed at
+the end of the line.
+.TP 8
+.B plusdirs
+After any matches defined by the compspec are generated,
+directory name completion is attempted and any
+matches are added to the results of the other actions.
+.RE
+.TP 8
+\fB\-A\fP \fIaction\fP
+The \fIaction\fP may be one of the following to generate a list of possible
+completions:
+.RS
+.TP 8
+.B alias
+Alias names. May also be specified as \fB\-a\fP.
+.TP 8
+.B arrayvar
+Array variable names.
+.TP 8
+.B binding
+\fBReadline\fP key binding names.
+.TP 8
+.B builtin
+Names of shell builtin commands. May also be specified as \fB\-b\fP.
+.TP 8
+.B command
+Command names. May also be specified as \fB\-c\fP.
+.TP 8
+.B directory
+Directory names. May also be specified as \fB\-d\fP.
+.TP 8
+.B disabled
+Names of disabled shell builtins.
+.TP 8
+.B enabled
+Names of enabled shell builtins.
+.TP 8
+.B export
+Names of exported shell variables. May also be specified as \fB\-e\fP.
+.TP 8
+.B file
+File names. May also be specified as \fB\-f\fP.
+.TP 8
+.B function
+Names of shell functions.
+.TP 8
+.B group
+Group names. May also be specified as \fB\-g\fP.
+.TP 8
+.B helptopic
+Help topics as accepted by the \fBhelp\fP builtin.
+.TP 8
+.B hostname
+Hostnames, as taken from the file specified by the
+.SM
+.B HOSTFILE
+shell variable.
+.TP 8
+.B job
+Job names, if job control is active. May also be specified as \fB\-j\fP.
+.TP 8
+.B keyword
+Shell reserved words. May also be specified as \fB\-k\fP.
+.TP 8
+.B running
+Names of running jobs, if job control is active.
+.TP 8
+.B service
+Service names. May also be specified as \fB\-s\fP.
+.TP 8
+.B setopt
+Valid arguments for the \fB\-o\fP option to the \fBset\fP builtin.
+.TP 8
+.B shopt
+Shell option names as accepted by the \fBshopt\fP builtin.
+.TP 8
+.B signal
+Signal names.
+.TP 8
+.B stopped
+Names of stopped jobs, if job control is active.
+.TP 8
+.B user
+User names. May also be specified as \fB\-u\fP.
+.TP 8
+.B variable
+Names of all shell variables. May also be specified as \fB\-v\fP.
+.RE
+.TP 8
+\fB\-G\fP \fIglobpat\fP
+The filename expansion pattern \fIglobpat\fP is expanded to generate
+the possible completions.
+.TP 8
+\fB\-W\fP \fIwordlist\fP
+The \fIwordlist\fP is split using the characters in the
+.SM
+.B IFS
+special variable as delimiters, and each resultant word is expanded.
+The possible completions are the members of the resultant list which
+match the word being completed.
+.TP 8
+\fB\-C\fP \fIcommand\fP
+\fIcommand\fP is executed in a subshell environment, and its output is
+used as the possible completions.
+.TP 8
+\fB\-F\fP \fIfunction\fP
+The shell function \fIfunction\fP is executed in the current shell
+environment.
+When it finishes, the possible completions are retrieved from the value
+of the
+.SM
+.B COMPREPLY
+array variable.
+.TP 8
+\fB\-X\fP \fIfilterpat\fP
+\fIfilterpat\fP is a pattern as used for filename expansion.
+It is applied to the list of possible completions generated by the
+preceding options and arguments, and each completion matching
+\fIfilterpat\fP is removed from the list.
+A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this
+case, any completion not matching \fIfilterpat\fP is removed.
+.TP 8
+\fB\-P\fP \fIprefix\fP
+\fIprefix\fP is added at the beginning of each possible completion
+after all other options have been applied.
+.TP 8
+\fB\-S\fP \fIsuffix\fP
+\fIsuffix\fP is appended to each possible completion
+after all other options have been applied.
+.PD
+.PP
+The return value is true unless an invalid option is supplied, an option
+other than \fB\-p\fP or \fB\-r\fP is supplied without a \fIname\fP
+argument, an attempt is made to remove a completion specification for
+a \fIname\fP for which no specification exists, or
+an error occurs adding a completion specification.
+.RE
+.TP
+\fBcompopt\fP [\fB\-o\fP \fIoption\fP] [\fB+o\fP \fIoption\fP] [\fIname\fP]
+Modify completion options for each \fIname\fP according to the
+\fIoption\fPs, or for the
+currently-execution completion if no \fIname\fPs are supplied.
+If no \fIoption\fPs are given, display the completion options for each
+\fIname\fP or the current completion.
+The possible values of \fIoption\fP are those valid for the \fBcomplete\fP
+builtin described above.
+.PP
+The return value is true unless an invalid option is supplied, an attempt
+is made to modify the options for a \fIname\fP for which no completion
+specification exists, or an output error occurs.
+.TP
\fBcontinue\fP [\fIn\fP]
Resume the next iteration of the enclosing
.BR for ,
must be \(>= 1. If
.I n
is greater than the number of enclosing loops, the last enclosing loop
-(the ``top-level'' loop) is resumed. The return value is 0 unless the
-shell is not executing a loop when
-.B continue
-is executed.
+(the ``top-level'' loop) is resumed.
+The return value is 0 unless \fIn\fP is not greater than or equal to 1.
.TP
+\fBdeclare\fP [\fB\-aAfFilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
.PD 0
-\fBdeclare\fP [\fB\-afFirx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP]]
.TP
-\fBtypeset\fP [\fB\-afFirx\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP]]
+\fBtypeset\fP [\fB\-aAfFilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
.PD
Declare variables and/or give them attributes.
If no \fIname\fPs are given then display the values of variables.
.IR name .
When
.B \-p
-is used, additional options are ignored.
+is used with \fIname\fP arguments, additional options are ignored.
+When
+.B \-p
+is supplied without \fIname\fP arguments, it will display the attributes
+and values of all variables having the attributes specified by the
+additional options.
+If no other options are supplied with \fB\-p\fP, \fBdeclare\fP will display
+the attributes and values of all shell variables. The \fB\-f\fP option
+will restrict the display to shell functions.
The
.B \-F
option inhibits the display of function definitions; only the
function name and attributes are printed.
-The
+If the \fBextdebug\fP shell option is enabled using \fBshopt\fP,
+the source file name and line number where the function is defined
+are displayed as well. The
.B \-F
option implies
.BR \-f .
.PD 0
.TP
.B \-a
-Each \fIname\fP is an array variable (see
+Each \fIname\fP is an indexed array variable (see
+.B Arrays
+above).
+.TP
+.B \-A
+Each \fIname\fP is an associative array variable (see
.B Arrays
above).
.TP
.B "ARITHMETIC EVALUATION" ") "
is performed when the variable is assigned a value.
.TP
+.B \-l
+When the variable is assigned a value, all upper-case characters are
+converted to lower-case.
+The upper-case attribute is disabled.
+.TP
.B \-r
Make \fIname\fPs readonly. These names cannot then be assigned values
by subsequent assignment statements or unset.
.TP
+.B \-t
+Give each \fIname\fP the \fItrace\fP attribute.
+Traced functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps from
+the calling shell.
+The trace attribute has no special meaning for variables.
+.TP
+.B \-u
+When the variable is assigned a value, all lower-case characters are
+converted to upper-case.
+The lower-case attribute is disabled.
+.TP
.B \-x
Mark \fIname\fPs for export to subsequent commands via the environment.
.PD
.PP
Using `+' instead of `\-'
-turns off the attribute instead, with the exception that \fB+a\fP
-may not be used to destroy an array variable. When used in a function,
+turns off the attribute instead,
+with the exceptions that \fB+a\fP
+may not be used to destroy an array variable and \fB+r\fB will not
+remove the readonly attribute.
+When used in a function,
makes each
\fIname\fP local, as with the
.B local
-command. The return value is 0 unless an invalid option is encountered,
-an attempt is made to define a function using "\-f foo=bar",
+command.
+If a variable name is followed by =\fIvalue\fP, the value of
+the variable is set to \fIvalue\fP.
+The return value is 0 unless an invalid option is encountered,
+an attempt is made to define a function using
+.if n ``\-f foo=bar'',
+.if t \f(CW\-f foo=bar\fP,
an attempt is made to assign a value to a readonly variable,
an attempt is made to assign a value to an array variable without
using the compound assignment syntax (see
above), one of the \fInames\fP is not a valid shell variable name,
an attempt is made to turn off readonly status for a readonly variable,
an attempt is made to turn off array status for an array variable,
-or an attempt is made to display a non-existent function with \-f.
+or an attempt is made to display a non-existent function with \fB\-f\fP.
.RE
.TP
-.B dirs [\fB\-clpv\fP] [+\fIn\fP] [\-\fIn\fP]
+.B dirs [+\fIn\fP] [\-\fIn\fP] [\fB\-cplv\fP]
Without options, displays the list of currently remembered directories.
The default display is on a single line with directory names separated
by spaces.
Without options, each
.I jobspec
is removed from the table of active jobs.
+If
+.I jobspec
+is not present, and neither \fB\-a\fB nor \fB\-r\fP is supplied,
+the shell's notion of the \fIcurrent job\fP is used.
If the \fB\-h\fP option is given, each
.I jobspec
is not removed from the table, but is marked so that
.B \-E
option disables the interpretation of these escape characters,
even on systems where they are interpreted by default.
+The \fBxpg_echo\fP shell option may be used to
+dynamically determine whether or not \fBecho\fP expands these
+escape characters by default.
.B echo
-does not interpret
-.B \-\-
-to mean the end of options.
+does not interpret \fB\-\-\fP to mean the end of options.
.B echo
interprets the following escape sequences:
.RS
backspace
.TP
.B \ec
-suppress trailing newline
+suppress further output
.TP
.B \ee
an escape character
.B \e\e
backslash
.TP
-.B \e\fInnn\fP
-the character whose ASCII code is the octal value \fInnn\fP
-(one to three digits)
+.B \e0\fInnn\fP
+the eight-bit character whose value is the octal value \fInnn\fP
+(zero to three octal digits)
.TP
-.B \ex\fInnn\fP
-the character whose ASCII code is the hexadecimal value \fInnn\fP
-(one to three digits)
+.B \ex\fIHH\fP
+the eight-bit character whose value is the hexadecimal value \fIHH\fP
+(one or two hex digits)
.PD
.RE
.TP
-\fBenable\fP [\fB\-adnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...]
+\fBenable\fP [\fB\-a\fP] [\fB\-dnps\fP] [\fB\-f\fP \fIfilename\fP] [\fIname\fP ...]
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 with specifying a full pathname,
+as a shell builtin to be executed without specifying a full pathname,
even though the shell normally searches for builtins before disk commands.
If \fB\-n\fP is used, each \fIname\fP
is disabled; otherwise,
.SM
.B PATH
instead of the shell builtin version, run
-\f(CWenable -n test\fP.
+.if t \f(CWenable -n test\fP.
+.if n ``enable -n test''.
The
.B \-f
option means to load the new builtin command
\fIspecial\fP builtins.
The return value is 0 unless a
.I name
-is not a shell builtin or there is a problem loading a new builtin
+is not a shell builtin or there is an error loading a new builtin
from a shared object.
.TP
\fBeval\fP [\fIarg\fP ...]
If the
.B \-l
option is supplied,
-the shell places a dash in the zeroth arg passed to
+the shell places a dash at the beginning of the zeroth argument passed to
.IR command .
This is what
.IR login (1)
.B EXIT
is executed before the shell terminates.
.TP
-.PD 0
\fBexport\fP [\fB\-fn\fP\^] [\fIname\fP[=\fIword\fP]] ...
+.PD 0
.TP
.B export \-p
.PD
of all names that are exported in this shell is printed.
The
.B \-n
-option causes the export property to be removed from the
-named variables.
+option causes the export property to be removed from each
+\fIname\fP.
+If a variable name is followed by =\fIword\fP, the value of
+the variable is set to \fIword\fP.
.B export
returns an exit status of 0 unless an invalid option is
encountered,
.I name
that is not a function.
.TP
+\fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-lnr\fP] [\fIfirst\fP] [\fIlast\fP]
.PD 0
-\fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-nlr\fP] [\fIfirst\fP] [\fIlast\fP]
.TP
\fBfc\fP \fB\-s\fP [\fIpat\fP=\fIrep\fP] [\fIcmd\fP]
.PD
.I last
is not specified it is set to
the current command for listing (so that
-.B fc \-l \-10
+.if n ``fc \-l \-10''
+.if t \f(CWfc \-l \-10\fP
prints the last 10 commands) and to
.I first
otherwise.
In the second form, \fIcommand\fP is re-executed after each instance
of \fIpat\fP is replaced by \fIrep\fP.
A useful alias to use with this is
-.if n ``r=fc -s'',
+.if n ``r="fc -s"'',
.if t \f(CWr='fc \-s'\fP,
so that typing
.if n ``r cc''
.B getopts
is used by shell procedures to parse positional parameters.
.I optstring
-contains the option letters to be recognized; if a letter
+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 and question mark characters may not be used as
+option characters.
Each time it is invoked,
.B getopts
places the next option in the shell variable
is not silent,
a question mark (\^\fB?\fP\^) is placed in
.IR name ,
+.SM
.B OPTARG
is unset, and a diagnostic message is printed.
If
It returns false if the end of options is encountered or an
error occurs.
.TP
-\fBhash\fP [\fB\-r\fP] [\fB\-p\fP \fIfilename\fP] [\fIname\fP]
+\fBhash\fP [\fB\-lr\fP] [\fB\-p\fP \fIfilename\fP] [\fB\-dt\fP] [\fIname\fP]
For each
.IR name ,
the full file name of the command is determined by searching
The
.B \-r
option causes the shell to forget all
-remembered locations. If no arguments are given, information
-about remembered commands is printed.
+remembered locations.
+The
+.B \-d
+option causes the shell to forget the remembered location of each \fIname\fP.
+If the
+.B \-t
+option is supplied, the full pathname to which each \fIname\fP corresponds
+is printed. If multiple \fIname\fP arguments are supplied with \fB\-t\fP,
+the \fIname\fP is printed before the hashed full pathname.
+The
+.B \-l
+option causes output to be displayed in a format that may be reused as input.
+If no arguments are given, or if only \fB\-l\fP is supplied,
+information about remembered commands is printed.
The return status is true unless a
.I name
is not found or an invalid option is supplied.
.TP
-\fBhelp\fP [\fIpattern\fP]
+\fBhelp\fP [\fB\-dms\fP] [\fIpattern\fP]
Display helpful information about builtin commands. If
.I pattern
is specified,
gives detailed help on all commands matching
.IR pattern ;
otherwise help for all the builtins and shell control structures
-is printed. The return status is 0 unless no command matches
+is printed.
+.RS
+.PD 0
+.TP
+.B \-d
+Display a short description of each \fIpattern\fP
+.TP
+.B \ -m
+Display the description of each \fIpattern\fP in a manpage-like format
+.TP
+.B \-s
+Display only a short usage synopsis for each \fIpattern\fP
+.PD
+.RE
+The return status is 0 unless no command matches
.IR pattern .
.TP
+\fBhistory [\fIn\fP]
.PD 0
-\fBhistory\fP [\fB\-c\fP] [\fIn\fP]
+.TP
+\fBhistory\fP \fB\-c\fP
+.TP
+\fBhistory \-d\fP \fIoffset\fP
.TP
\fBhistory\fP \fB\-anrw\fP [\fIfilename\fP]
.TP
.I n
lists only the last
.I n
-lines. If \fIfilename\fP is supplied, it is used as the
+lines.
+If the shell variable \fBHISTTIMEFORMAT\fP is set and not null,
+it is used as a format string for \fIstrftime\fP(3) to display
+the time stamp associated with each displayed history entry.
+No intervening blank is printed between the formatted time stamp
+and the history line.
+If \fIfilename\fP is supplied, it is used as the
name of the history file; if not, the value of
.SM
.B HISTFILE
.RS
.PD 0
.TP
+.B \-c
+Clear the history list by deleting all the entries.
+.TP
+\fB\-d\fP \fIoffset\fP
+Delete the history entry at position \fIoffset\fP.
+.TP
.B \-a
Append the ``new'' history lines (history lines entered since the
beginning of the current \fBbash\fP session) to the history file.
Write the current history to the history file, overwriting the
history file's contents.
.TP
-.B \-c
-Clear the history list by deleting all the entries.
-.TP
.B \-p
Perform history substitution on the following \fIargs\fP and display
the result on the standard output.
are added.
.PD
.PP
-The return value is 0 unless an invalid option is encountered or an
-error occurs while reading or writing the history file.
+If the \fBHISTTIMEFORMAT\fP is set, the time stamp information
+associated with each history entry is written to the history file,
+marked with the history comment character.
+When the history file is read, lines beginning with the history
+comment character followed immediately by a digit are interpreted
+as timestamps for the previous history line.
+The return value is 0 unless an invalid option is encountered, an
+error occurs while reading or writing the history file, an invalid
+\fIoffset\fP is supplied as an argument to \fB\-d\fP, or the
+history expansion supplied as an argument to \fB\-p\fP fails.
.RE
.TP
-.PD 0
\fBjobs\fP [\fB\-lnprs\fP] [ \fIjobspec\fP ... ]
+.PD 0
.TP
\fBjobs\fP \fB\-x\fP \fIcommand\fP [ \fIargs\fP ... ]
.PD
returning its exit status.
.RE
.TP
-.PD 0
\fBkill\fP [\fB\-s\fP \fIsigspec\fP | \fB\-n\fP \fIsignum\fP | \fB\-\fP\fIsigspec\fP] [\fIpid\fP | \fIjobspec\fP] ...
+.PD 0
.TP
\fBkill\fP \fB\-l\fP [\fIsigspec\fP | \fIexit_status\fP]
.PD
or
.IR jobspec .
.I sigspec
-is either a signal name such as
+is either a case-insensitive signal name such as
.SM
.B SIGKILL
-or a signal number;
-.I signum
-is a signal number. If
-.I sigspec
-is a signal name, the name may be
-given with or without the
+(with or without the
.SM
.B SIG
-prefix.
+prefix) or a signal number;
+.I signum
+is a signal number.
If
.I sigspec
is not present, then
.B let
returns 1; 0 is returned otherwise.
.TP
-\fBlocal\fP [\fIname\fP[=\fIvalue\fP] ...]
+\fBlocal\fP [\fIoption\fP] [\fIname\fP[=\fIvalue\fP] ...]
For each argument, a local variable named
.I name
is created, and assigned
.IR value .
+The \fIoption\fP can be any of the options accepted by \fBdeclare\fP.
When
.B local
is used within a function, it causes the variable
.B local
when not within a function. The return status is 0 unless
.B local
-is used outside a function, or an invalid
+is used outside a function, an invalid
.I name
-is supplied.
+is supplied, or
+\fIname\fP is a readonly variable.
.TP
.B logout
Exit a login shell.
.TP
+\fBmapfile\fP [\fB\-n\fP \fIcount\fP] [\fB\-O\fP \fIorigin\fP] [\fB\-s\fP \fIcount\fP] [\fB\-t\fP] [\fB\-u\fP \fIfd\fP] [\fB\-C\fP \fIcallback\fP] [\fB\-c\fP \fIquantum\fP] [\fIarray\fP]
+Read lines from the standard input into array variable
+.IR array ,
+or from file descriptor
+.IR fd
+if the
+.B \-u
+option is supplied.
+The variable \fBMAPFILE\fP is the default \fIarray\fP.
+Options, if supplied, have the following meanings:
+.RS
+.PD 0
+.TP
+.B \-n
+Copy at most
+.I count
+lines. If \fIcount\fP is 0, all lines are copied.
+.TP
+.B \-O
+Begin assigning to
+.I array
+at index
+.IR origin .
+The default index is 0.
+.TP
+.B \-s
+Discard the first \fIcount\fP lines read.
+.TP
+.B \-t
+Remove a trailing line from each line read.
+.TP
+.B \-u
+Read lines from file descriptor \fIfd\fP instead of the standard input.
+.TP
+.B \-C
+Evaluate
+.I callback
+each time \fIquantum\fP lines are read. The \fB\-c\fP option specifies
+.IR quantum .
+.TP
+.B \-c
+Specify the number of lines read between each call to
+.IR callback .
+.PD
+.PP
+If
+.B \-C
+is specified without
+.BR \-c ,
+the default quantum is 5000.
+.PP
+If not supplied with an explicit origin, \fBmapfile\fP will clear \fIarray\fP
+before assigning to it.
+.PP
+\fBmapfile\fP returns successfully unless an invalid option or option
+argument is supplied, or \fIarray\fP is invalid or unassignable.
+.RE
+.TP
\fBpopd\fP [\-\fBn\fP] [+\fIn\fP] [\-\fIn\fP]
Removes entries from the directory stack. With no arguments,
removes the top directory from the stack, and performs a
.RS
.PD 0
.TP
+.B \-n
+Suppresses the normal change of directory when removing directories
+from the stack, so that only the stack is manipulated.
+.TP
\fB+\fP\fIn\fP
Removes the \fIn\fPth entry counting from the left of the list
shown by
.BR dirs ,
-starting with zero. For example: ``popd +0''
-removes the first directory, ``popd +1'' the second.
+starting with zero. For example:
+.if n ``popd +0''
+.if t \f(CWpopd +0\fP
+removes the first directory,
+.if n ``popd +1''
+.if t \f(CWpopd +1\fP
+the second.
.TP
\fB\-\fP\fIn\fP
Removes the \fIn\fPth entry counting from the right of the list
shown by
.BR dirs ,
-starting with zero. For example: ``popd -0''
-removes the last directory, ``popd -1'' the next to last.
-.TP
-.B \-n
-Suppresses the normal change of directory when removing directories
-from the stack, so that only the stack is manipulated.
+starting with zero. For example:
+.if n ``popd -0''
+.if t \f(CWpopd -0\fP
+removes the last directory,
+.if n ``popd -1''
+.if t \f(CWpopd -1\fP
+the next to last.
.PD
.PP
If the
directory change fails.
.RE
.TP
-\fBprintf\fP \fIformat\fP [\fIarguments\fP]
+\fBprintf\fP [\fB\-v\fP \fIvar\fP] \fIformat\fP [\fIarguments\fP]
Write the formatted \fIarguments\fP to the standard output under the
control of the \fIformat\fP.
The \fIformat\fP is a character string which contains three types of objects:
escape sequences, which are converted and copied to the standard output, and
format specifications, each of which causes printing of the next successive
\fIargument\fP.
-In addition to the standard \fIprintf\fP(1) formats, %b causes
+In addition to the standard \fIprintf\fP(1) formats, \fB%b\fP causes
\fBprintf\fP to expand backslash escape sequences in the corresponding
-\fIargument\fP, and %q causes \fBprintf\fP to output the corresponding
+\fIargument\fP (except that \fB\ec\fP terminates output, backslashes in
+\fB\e\(aq\fP, \fB\e"\fP, and \fB\e?\fP are not removed, and octal escapes
+beginning with \fB\e0\fP may contain up to four digits),
+and \fB%q\fP causes \fBprintf\fP to output the corresponding
\fIargument\fP in a format that can be reused as shell input.
.sp 1
+The \fB\-v\fP option causes the output to be assigned to the variable
+\fIvar\fP rather than being printed to the standard output.
+.sp 1
The \fIformat\fP is reused as necessary to consume all of the \fIarguments\fP.
If the \fIformat\fP requires more \fIarguments\fP than are supplied, the
extra format specifications behave as if a zero value or null string, as
-appropriate, had been supplied.
+appropriate, had been supplied. The return value is zero on success,
+non-zero on failure.
.TP
+\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP]
.PD 0
-\fBpushd\fP [\fB\-n\fP] [\fIdir\fP]
.TP
-\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP]
+\fBpushd\fP [\fB\-n\fP] [\fIdir\fP]
.PD
Adds a directory to the top of the directory stack, or rotates
the stack, making the new top of the stack the current working
.RS
.PD 0
.TP
+.B \-n
+Suppresses the normal change of directory when adding directories
+to the stack, so that only the stack is manipulated.
+.TP
\fB+\fP\fIn\fP
Rotates the stack so that the \fIn\fPth directory
(counting from the left of the list shown by
.BR dirs ,
starting with zero) is at the top.
.TP
-.B \-n
-Suppresses the normal change of directory when adding directories
-to the stack, so that only the stack is manipulated.
-.TP
-.B dir
+.I dir
Adds
.I dir
to the directory stack at the top, making it the
.RE
.TP
\fBpwd\fP [\fB\-LP\fP]
-Print the absolute file name of the current working directory.
-The file name printed contains no symbolic links if the
+Print the absolute pathname of the current working directory.
+The pathname printed contains no symbolic links if the
.B \-P
option is supplied or the
.B \-o physical
builtin command is enabled.
If the
.B \-L
-option is used, symbolic links are followed.
+option is used, the pathname printed may contain symbolic links.
The return status is 0 unless an error occurs while
reading the name of the current directory or an
invalid option is supplied.
.TP
-\fBread\fP [\fB\-er\fP] [\fB\-a\fP \fIaname\fP] [\fB\-p\fP \fIprompt\fP] [\fIname\fP ...]
-One line is read from the standard input, and the first word
+\fBread\fP [\fB\-ers\fP] [\fB\-a\fP \fIaname\fP] [\fB\-d\fP \fIdelim\fP] [\fB\-\fP \fItext\fP] [\fB\-n\fP \fInchars\fP] [\fB\-p\fP \fIprompt\fP] [\fB\-t\fP \fItimeout\fP] [\fB\-u\fP \fIfd\fP] [\fIname\fP ...]
+One line is read from the standard input, or from the file descriptor
+\fIfd\fP supplied as an argument to the \fB\-u\fP option, and the first word
is assigned to the first
.IR name ,
the second word to the second
and so on, with leftover words and their intervening separators assigned
to the last
.IR name .
-If there are fewer words read from the standard input than names,
+If there are fewer words read from the input stream than names,
the remaining names are assigned empty values.
The characters in
.SM
.B IFS
are used to split the line into words.
+The backslash character (\fB\e\fP) may be used to remove any special
+meaning for the next character read and for line continuation.
Options, if supplied, have the following meanings:
.RS
.PD 0
.TP
-.B \-r
-A backslash-newline pair is not ignored, and
-the backslash is considered to be part of the line.
-.TP
-.B \-p
-Display \fIprompt\fP, without a
-trailing newline, before attempting to read any input. The prompt
-is displayed only if input is coming from a terminal.
-.TP
-.B \-a
+.B \-a \fIaname\fP
The words are assigned to sequential indices
of the array variable
.IR aname ,
is unset before any new values are assigned.
Other \fIname\fP arguments are ignored.
.TP
+.B \-d \fIdelim\fP
+The first character of \fIdelim\fP is used to terminate the input line,
+rather than newline.
+.TP
.B \-e
If the standard input
is coming from a terminal,
.SM
.B READLINE
above) is used to obtain the line.
+Readline uses the current (or default, if line editing was not previously
+active) editing settings.
+.TP
+.B \-i \fItext\fP
+If
+.B readline
+is being used to read the line, \fItext\fP is placed into the editing
+buffer before editing begins.
+.TP
+.B \-n \fInchars\fP
+\fBread\fP returns after reading \fInchars\fP characters rather than
+waiting for a complete line of input.
+.TP
+.B \-p \fIprompt\fP
+Display \fIprompt\fP on standard error, without a
+trailing newline, before attempting to read any input. The prompt
+is displayed only if input is coming from a terminal.
+.TP
+.B \-r
+Backslash does not act as an escape character.
+The backslash is considered to be part of the line.
+In particular, a backslash-newline pair may not be used as a line
+continuation.
+.TP
+.B \-s
+Silent mode. If input is coming from a terminal, characters are
+not echoed.
+.TP
+.B \-t \fItimeout\fP
+Cause \fBread\fP to time out and return failure if a complete line of
+input is not read within \fItimeout\fP seconds.
+\fItimeout\fP may be a decimal number with a fractional portion following
+the decimal point.
+This option is only effective if \fBread\fP is reading input from a
+terminal, pipe, or other special file; it has no effect when reading
+from regular files.
+If \fItimeout\fP is 0, \fBread\fP returns success if input is available on
+the specified file descriptor, failure otherwise.
+The exit status is greater than 128 if the timeout is exceeded.
+.TP
+.B \-u \fIfd\fP
+Read input from file descriptor \fIfd\fP.
.PD
.PP
If no
are supplied, the line read is assigned to the variable
.SM
.BR REPLY .
-The return code is zero, unless end-of-file is encountered.
+The return code is zero, unless end-of-file is encountered, \fBread\fP
+times out (in which case the return code is greater than 128), or an
+invalid file descriptor is supplied as the argument to \fB\-u\fP.
.RE
.TP
-\fBreadonly\fP [\fB\-apf\fP] [\fIname\fP ...]
+\fBreadonly\fP [\fB\-aApf\fP] [\fIname\fP[=\fIword\fP] ...]
.PD
The given
\fInames\fP are marked readonly; the values of these
marked.
The
.B \-a
-option restricts the variables to arrays.
+option restricts the variables to indexed arrays; the
+.B \-A
+option restricts the variables to associative arrays.
If no
.I name
arguments are given, or if the
option is supplied, a list of all readonly names is printed.
The
.B \-p
-option causes output to be displayed in a format thatmay be reused as input.
+option causes output to be displayed in a format that
+may be reused as input.
+If a variable name is followed by =\fIword\fP, the value of
+the variable is set to \fIword\fP.
The return status is 0 unless an invalid option is encountered,
one of the
.I names
script as the exit status of the script. If used outside a
function and not during execution of a script by \fB.\fP\^,
the return status is false.
+Any command associated with the \fBRETURN\fP trap is executed
+before execution resumes after the function or script.
.TP
-\fBset\fP [\fB\-\-abefhkmnptuvxBCHP\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...]
+\fBset\fP [\fB\-\-abefhkmnptuvxBCEHPT\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...]
+.PD 0
+.TP
+\fBset\fP [\fB+abefhkmnptuvxBCEHPT\fP] [\fB+o\fP \fIoption\fP] [\fIarg\fP ...]
+.PD
Without options, the name and value of each shell variable are displayed
-in a format that can be reused as input.
+in a format that can be reused as input
+for setting or resetting the currently-set variables.
+Read-only variables cannot be reset.
+In \fIposix mode\fP, only shell variables are listed.
The output is sorted according to the current locale.
When options are specified, they set or unset shell attributes.
-Any arguments remaining after the options are processed are treated
+Any arguments remaining after option processing are treated
as values for the positional parameters and are assigned, in order, to
.BR $1 ,
.BR $2 ,
.PD 0
.TP 8
.B \-a
-Automatically mark variables which are modified or created for export
-to the environment of subsequent commands.
+Automatically mark variables and functions which are modified or
+created for export to the environment of subsequent commands.
.TP 8
.B \-b
Report the status of terminated background jobs
Exit immediately if a \fIsimple command\fP (see
.SM
.B SHELL GRAMMAR
-above) exits with a non-zero status. The shell does not exit if the
-command that fails is part of an
-.I until
+above) exits with a non-zero status.
+The shell does not exit if the
+command that fails is part of the command list immediately following a
+.B while
or
-.I while
-loop,
-part of an
-.I if
-statement, part of a
+.B until
+keyword,
+part of the test in an
+.B if
+statement, part of a command executed in a
.B &&
or
.B \(bv\(bv
-list, or if the command's return value is
+list,
+any command in a pipeline but the last,
+or if the command's return value is
being inverted via
.BR ! .
+Failing simple commands that are part of shell functions or command lists
+enclosed in braces or parentheses satisfying the above conditions do not
+cause the shell to exit.
+A trap on \fBERR\fP, if set, is executed before the shell exits.
.TP 8
.B \-f
Disable pathname expansion.
with the
.B \-\-noediting
option.
+This also affects the editing interface used for \fBread \-e\fP.
+.TP 8
+.B errtrace
+Same as
+.BR \-E .
+.TP 8
+.B functrace
+Same as
+.BR \-T .
.TP 8
.B errexit
Same as
This option is on by default in interactive shells.
.TP 8
.B ignoreeof
-The effect is as if the shell command \f(CWIGNOREEOF=10\fP had been executed
+The effect is as if the shell command
+.if t \f(CWIGNOREEOF=10\fP
+.if n ``IGNOREEOF=10''
+had been executed
(see
.B Shell Variables
above).
Same as
.BR \-f .
.TP 8
+.B nolog
+Currently ignored.
+.TP 8
.B notify
Same as
.BR \-b .
Same as
.BR \-P .
.TP 8
+.B 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.
+.TP 8
.B posix
Change the behavior of
.B bash
where the default operation differs
-from the POSIX 1003.2 standard to match the standard.
+from the POSIX standard to match the standard (\fIposix mode\fP).
.TP 8
.B privileged
Same as
.TP 8
.B vi
Use a vi-style command line editing interface.
+This also affects the editing interface used for \fBread \-e\fP.
.TP 8
.B xtrace
Same as
Turn on
.I privileged
mode. In this mode, the
+.SM
.B $ENV
-file is not processed, shell functions are not inherited from the
-environment, and the variable
-The \fBSHELLOPTS\fP variable, if it appears in the environment, is ignored.
-This is enabled automatically on startup if the effective user (group)
-id is not equal to the real user (group) id.
+and
+.SM
+.B $BASH_ENV
+files are not processed, shell functions are not inherited from the
+environment, and the
+.SM
+.BR SHELLOPTS ,
+.BR CDPATH ,
+and
+.B GLOBIGNORE
+variables, if they appear in the environment, are ignored.
+If the shell is started with the effective user (group) id not equal to the
+real user (group) id, and the \fB\-p\fP option is not supplied, these actions
+are taken and the effective user id is set to the real user id.
+If the \fB\-p\fP 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.
.TP 8
.TP 8
.B \-x
After expanding each \fIsimple command\fP,
-display the expanded value of
+\fBfor\fP command, \fBcase\fP command, \fBselect\fP command, or
+arithmetic \fBfor\fP command, display the expanded value of
.SM
.BR PS4 ,
-followed by the command and its expanded arguments.
+followed by the command and its expanded arguments
+or associated word list.
.TP 8
.B \-B
The shell performs brace expansion (see
instead of
.BR > .
.TP 8
+.B \-E
+If set, any trap on \fBERR\fP is inherited by shell functions, command
+substitutions, and commands executed in a subshell environment.
+The \fBERR\fP trap is normally not inherited in such cases.
+.TP 8
.B \-H
Enable
.B !
follows the logical chain of directories when performing commands
which change the current directory.
.TP 8
+.B \-T
+If set, any traps on \fBDEBUG\fP and \fBRETURN\fP are inherited by shell
+functions, command substitutions, and commands executed in a
+subshell environment.
+The \fBDEBUG\fP and \fBRETURN\fP traps are normally not inherited
+in such cases.
+.TP 8
.B \-\-
If no arguments follow this option, then the positional parameters are
unset. Otherwise, the positional parameters are set to the
.if n .sp 1v
.PD 0
.TP 8
+.B autocd
+If set, a command name that is the name of a directory is executed as if
+it were the argument to the \fBcd\fP command.
+This option is only used by interactive shells.
+.TP 8
.B cdable_vars
If set, an argument to the
.B cd
table exists before trying to execute it. If a hashed command no
longer exists, a normal path search is performed.
.TP 8
+.B checkjobs
+If set, \fBbash\fP lists the status of any stopped and running jobs before
+exiting an interactive shell. If any jobs are running, this causes
+the exit to be deferred until a second exit is attempted without an
+intervening command (see \fBJOB CONTROL\fP above). The shell always
+postpones exiting if any jobs are stopped.
+.TP 8
.B checkwinsize
If set, \fBbash\fP checks the window size after each command
and, if necessary, updates the values of
command in the same history entry. This allows
easy re-editing of multi-line commands.
.TP 8
+.B compat31
+If set,
+.B bash
+changes its behavior to that of version 3.1 with respect to quoted
+arguments to the conditional command's =~ operator.
+.TP 8
+.B dirspell
+If set,
+.B bash
+attempts spelling correction on directory names during word completion
+if the directory name initially supplied does not exist.
+.TP 8
.B dotglob
If set,
.B bash
.BR ALIASES .
This option is enabled by default for interactive shells.
.TP 8
+.B extdebug
+If set, behavior intended for use by debuggers is enabled:
+.RS
+.TP
+.B 1.
+The \fB\-F\fP option to the \fBdeclare\fP builtin displays the source
+file name and line number corresponding to each function name supplied
+as an argument.
+.TP
+.B 2.
+If the command run by the \fBDEBUG\fP trap returns a non-zero value, the
+next command is skipped and not executed.
+.TP
+.B 3.
+If the command run by the \fBDEBUG\fP trap returns a value of 2, and the
+shell is executing in a subroutine (a shell function or a shell script
+executed by the \fB.\fP or \fBsource\fP builtins), a call to
+\fBreturn\fP is simulated.
+.TP
+.B 4.
+\fBBASH_ARGC\fP and \fBBASH_ARGV\fP are updated as described in their
+descriptions above.
+.TP
+.B 5.
+Function tracing is enabled: command substitution, shell functions, and
+subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the
+\fBDEBUG\fP and \fBRETURN\fP traps.
+.TP
+.B 6.
+Error tracing is enabled: command substitution, shell functions, and
+subshells invoked with \fB(\fP \fIcommand\fP \fB)\fP inherit the
+\fBERROR\fP trap.
+.RE
+.TP 8
.B extglob
If set, the extended pattern matching features described above under
\fBPathname Expansion\fP are enabled.
.TP 8
+.B extquote
+If set, \fB$\fP\(aq\fIstring\fP\(aq and \fB$\fP"\fIstring\fP" quoting is
+performed within \fB${\fP\fIparameter\fP\fB}\fP expansions
+enclosed in double quotes. This option is enabled by default.
+.TP 8
+.B failglob
+If set, patterns which fail to match filenames during pathname expansion
+result in an expansion error.
+.TP 8
+.B force_fignore
+If set, the suffixes specified by the \fBFIGNORE\fP shell variable
+cause words to be ignored when performing word completion even if
+the ignored words are the only possible completions.
+See
+.SM
+\fBSHELL VARIABLES\fP
+above for a description of \fBFIGNORE\fP.
+This option is enabled by default.
+.TP 8
+.B globstar
+If set, the pattern \fB**\fP used in a filename expansion context will
+match a files and zero or more directories and subdirectories.
+If the pattern is followed by a \fB/\fP, only directories and
+subdirectories match.
+.TP 8
+.B gnu_errfmt
+If set, shell error messages are written in the standard GNU error
+message format.
+.TP 8
.B histappend
If set, the history list is appended to the file named by the value
of the
option is enabled, multi-line commands are saved to the history with
embedded newlines rather than using semicolon separators where possible.
.TP 8
+.B login_shell
+The shell sets this option if it is started as a login shell (see
+.SM
+.B "INVOCATION"
+above).
+The value may not be changed.
+.TP 8
.B mailwarn
If set, and a file that \fBbash\fP is checking for mail has been
accessed since the last time it was checked, the message ``The mail in
\fImailfile\fP has been read'' is displayed.
.TP 8
+.B no_empty_cmd_completion
+If set, and
+.B readline
+is being used,
+.B bash
+will not attempt to search the \fBPATH\fP for possible completions when
+completion is attempted on an empty line.
+.TP 8
.B nocaseglob
If set,
.B bash
.B Pathname Expansion
above).
.TP 8
+.B nocasematch
+If set,
+.B bash
+matches patterns in a case\-insensitive fashion when performing matching
+while executing \fBcase\fP or \fB[[\fP conditional commands.
+.TP 8
.B nullglob
If set,
.B bash
above)
to expand to a null string, rather than themselves.
.TP 8
+.B progcomp
+If set, the programmable completion facilities (see
+\fBProgrammable Completion\fP above) are enabled.
+This option is enabled by default.
+.TP 8
.B promptvars
-If set, prompt strings undergo variable and parameter expansion after
-being expanded as described in
+If set, prompt strings undergo
+parameter expansion, command substitution, arithmetic
+expansion, and quote removal after being expanded as described in
.SM
.B PROMPTING
above. This option is enabled by default.
.TP 8
+.B restricted_shell
+The shell sets this option if it is started in restricted mode (see
+.SM
+.B "RESTRICTED SHELL"
+below).
+The value may not be changed.
+This is not reset when the startup files are executed, allowing
+the startup files to discover whether or not a shell is restricted.
+.TP 8
.B shift_verbose
If set, the
.B shift
.B PATH
to find the directory containing the file supplied as an argument.
This option is enabled by default.
+.TP 8
+.B xpg_echo
+If set, the \fBecho\fP builtin expands backslash-escape sequences
+by default.
.RE
.TP
\fBsuspend\fP [\fB\-f\fP]
Suspend the execution of this shell until it receives a
.SM
.B SIGCONT
-signal. The
+signal. A login shell cannot be suspended; the
.B \-f
-option says not to complain if this is
-a login shell; just suspend anyway. The return status is 0 unless
-the shell is a login shell and
+option can be used to override this and force the suspension.
+The return status is 0 unless the shell is a login shell and
.B \-f
is not supplied, or if job control is not enabled.
.TP
-.PD 0
\fBtest\fP \fIexpr\fP
+.PD 0
.TP
\fB[\fP \fIexpr\fP \fB]\fP
Return a status of 0 or 1 depending on
Expressions are composed of the primaries described above under
.SM
.BR "CONDITIONAL EXPRESSIONS" .
+\fBtest\fP does not accept any options, nor does it accept and ignore
+an argument of \fB\-\-\fP as signifying the end of options.
.if t .sp 0.5
.if n .sp 1
Expressions may be combined using the following operators, listed
in decreasing order of precedence.
+The evaluation depends on the number of arguments; see below.
.RS
.PD 0
.TP
.BR "CONDITIONAL EXPRESSIONS" ,
the result of the expression is the result of the binary test using
the first and third arguments as operands.
+The \fB\-a\fP and \fB\-o\fP operators are considered binary operators
+when there are three arguments.
If the first argument is \fB!\fP, the value is the negation of
the two-argument test using the second and third arguments.
If the first argument is exactly \fB(\fP and the third argument is
exactly \fB)\fP, the result is the one-argument test of the second
argument.
Otherwise, the expression is false.
-The \fB\-a\fP and \fB\-o\fP operators are considered binary operators
-in this case.
.TP
4 arguments
If the first argument is \fB!\fP, the result is the negation of
Print the accumulated user and system times for the shell and
for processes run from the shell. The return status is 0.
.TP
-\fBtrap\fP [\fB\-lp\fP] [\fIarg\fP] [\fIsigspec\fP ...]
+\fBtrap\fP [\fB\-lp\fP] [[\fIarg\fP] \fIsigspec\fP ...]
The command
.I arg
is to be read and executed when the shell receives
.IR sigspec .
If
.I arg
-is absent or
+is absent (and there is a single \fIsigspec\fP) or
.BR \- ,
-all specified signals are
-reset to their original values (the values they had
+each specified signal is
+reset to its original disposition (the value it had
upon entrance to the shell).
If
.I arg
is ignored by the shell and by the commands it invokes.
If
.I arg
-is
+is not present and
.B \-p
-then the trap commands associated with
-each
+has been supplied, then the trap commands associated with each
.I sigspec
-are displayed. If no arguments are supplied or if
-only
+are displayed.
+If no arguments are supplied or if only
.B \-p
is given,
.B trap
-prints the list of commands associated with each signal number.
+prints the list of commands associated with each signal.
+The
+.B \-l
+option causes the shell to print a list of signal names and
+their corresponding numbers.
Each
.I sigspec
is either
a signal name defined in <\fIsignal.h\fP>, or a signal number.
+Signal names are case insensitive and the SIG prefix is optional.
If a
.I sigspec
is
.B EXIT
(0) the command
.I arg
-is executed on exit from the shell. If a
+is executed on exit from the shell.
+If a
.I sigspec
is
.SM
.BR DEBUG ,
the command
.I arg
-is executed after every \fIsimple command\fP (see
+is executed before every \fIsimple command\fP, \fIfor\fP command,
+\fIcase\fP command, \fIselect\fP command, every arithmetic \fIfor\fP
+command, and before the first command executes in a shell function (see
.SM
.B SHELL GRAMMAR
above).
+Refer to the description of the \fBextdebug\fP option to the
+\fBshopt\fP builtin for details of its effect on the \fBDEBUG\fP trap.
+If a
+.I sigspec
+is
+.SM
+.BR ERR ,
+the command
+.I arg
+is executed whenever a simple command has a non\-zero exit status,
+subject to the following conditions.
The
-.B \-l
-option causes the shell to print a list of signal names and
-their corresponding numbers.
+.SM
+.B ERR
+trap is not executed if the failed
+command is part of the command list immediately following a
+.B while
+or
+.B until
+keyword,
+part of the test in an
+.I if
+statement, part of a command executed in a
+.B &&
+or
+.B \(bv\(bv
+list, or if the command's return value is
+being inverted via
+.BR ! .
+These are the same conditions obeyed by the \fBerrexit\fP option.
+If a
+.I sigspec
+is
+.SM
+.BR RETURN ,
+the command
+.I arg
+is executed each time a shell function or a script executed with the
+\fB.\fP or \fBsource\fP 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.
+Trapped signals that are not being ignored are reset to their original
+values in a child process when it is created.
The return status is false if any
.I sigspec
is invalid; otherwise
.B trap
returns true.
.TP
-\fBtype\fP [\fB\-atp\fP] \fIname\fP [\fIname\fP ...]
+\fBtype\fP [\fB\-aftpP\fP] \fIname\fP [\fIname\fP ...]
With no options,
indicate how each
.I name
that would be executed if
.I name
were specified as a command name,
-or nothing if \f(CWtype -t name\fP
+or nothing if
+.if t \f(CWtype -t name\fP
+.if n ``type -t name''
+would not return
+.IR file .
+The
+.B \-P
+option forces a
+.SM
+.B PATH
+search for each \fIname\fP, even if
+.if t \f(CWtype -t name\fP
+.if n ``type -t name''
would not return
.IR file .
If a command is hashed,
.B \-p
-prints the hashed value, not necessarily the file that appears
+and
+.B \-P
+print the hashed value, not necessarily the file that appears
first in
.SM
.BR PATH .
The table of hashed commands is not consulted
when using
.BR \-a .
+The
+.B \-f
+option suppresses shell function lookup, as with the \fBcommand\fP builtin.
.B type
-returns true if any of the arguments are found, false if
-none are found.
+returns true if all of the arguments are found, false if
+any are not found.
.TP
-\fBulimit\fP [\fB\-SHacdflmnpstuv\fP [\fIlimit\fP]]
+\fBulimit\fP [\fB\-HSTabcdefilmnpqrstuvx\fP [\fIlimit\fP]]
Provides control over the resources available to the shell and to
-processes started by it, on systems that allow such control. The
-value of
-.I limit
-can be a number in the unit specified for the resource, or the
-value
-.BR unlimited .
+processes started by it, on systems that allow such control.
The \fB\-H\fP and \fB\-S\fP options specify that the hard or soft limit is
-set for the given resource. A hard limit cannot be increased once it
-is set; a soft limit may be increased up to the value of the hard limit.
+set for the given resource.
+A hard limit cannot be increased by a non-root user once it is set;
+a soft limit may be increased up to the value of the hard limit.
If neither \fB\-H\fP nor \fB\-S\fP is specified, both the soft and hard
limits are set.
+The value of
+.I limit
+can be a number in the unit specified for the resource
+or one of the special values
+.BR hard ,
+.BR soft ,
+or
+.BR unlimited ,
+which stand for the current hard limit, the current soft limit, and
+no limit, respectively.
If
.I limit
is omitted, the current value of the soft limit of the resource is
.B \-a
All current limits are reported
.TP
+.B \-b
+The maximum socket buffer size
+.TP
.B \-c
The maximum size of core files created
.TP
.B \-d
The maximum size of a process's data segment
.TP
+.B \-e
+The maximum scheduling priority ("nice")
+.TP
.B \-f
-The maximum size of files created by the shell
+The maximum size of files written by the shell and its children
+.TP
+.B \-i
+The maximum number of pending signals
.TP
.B \-l
The maximum size that may be locked into memory
.B \-p
The pipe size in 512-byte blocks (this may not be set)
.TP
+.B \-q
+The maximum number of bytes in POSIX message queues
+.TP
+.B \-r
+The maximum real-time scheduling priority
+.TP
.B \-s
The maximum stack size
.TP
.TP
.B \-v
The maximum amount of virtual memory available to the shell
+.TP
+.B \-x
+The maximum number of file locks
+.TP
+.B \-T
+The maximum number of threads
.PD
.PP
If
.BR \-p ,
which is in units of 512-byte blocks,
and
-.B \-n
+.BR \-T ,
+.BR \-b ,
+.BR \-n ,
and
.BR \-u ,
-which are unscaled values. The return status is 0
-unless an invalid option is encountered, a non-numeric argument
-other than \fBunlimited\fP is supplied as \fIlimit\fP, or an
-error occurs while setting a new limit.
+which are unscaled values.
+The return status is 0 unless an invalid option or argument is supplied,
+or an error occurs while setting a new limit.
.RE
.TP
\fBumask\fP [\fB\-p\fP] [\fB\-S\fP] [\fImode\fP]
.IR chmod (1).
If
.I mode
-is omitted, or if the
-.B \-S
-option is supplied, the
-current value of the mask is printed.
+is omitted, the current value of the mask is printed.
The
.B \-S
option causes the mask to be printed in symbolic form; the
no \fImode\fP argument was supplied, and false otherwise.
.TP
\fBunalias\fP [\-\fBa\fP] [\fIname\fP ...]
-Remove \fIname\fPs from the list of defined aliases. If
+Remove each \fIname\fP from the list of defined aliases. If
.B \-a
is supplied, all alias definitions are removed. The return
value is true unless a supplied
Read-only variables may not be unset.
If
.B \-f
-is specifed,
-each
+is specified, each
.I name
refers to a shell function, and the function definition
is removed.
.BR LINENO ,
.SM
.BR HISTCMD ,
+.SM
+.BR FUNCNAME ,
+.SM
+.BR GROUPS ,
or
.SM
.B DIRSTACK
are unset, they lose their special properties, even if they are
subsequently reset. The exit status is true unless a
.I name
-does not exist or is readonly.
+is readonly.
.TP
-\fBwait\fP [\fIn\fP]
-Wait for the specified process and return its termination
-status.
+\fBwait\fP [\fIn ...\fP]
+Wait for each specified process and return its termination status.
+Each
.I n
may be a process
ID or a job specification; if a job spec is given, all processes
.\" bash_builtins
.if \n(zZ=1 .ig zZ
.SH "RESTRICTED SHELL"
+.\" rbash.1
+.zY
.PP
If
.B bash
changing directories with \fBcd\fP
.IP \(bu
setting or unsetting the values of
-.B SHELL
+.BR SHELL ,
+.BR PATH ,
+.BR ENV ,
or
-.B PATH
+.B BASH_ENV
.IP \(bu
specifying command names containing
.B /
.B .
builtin command
.IP \(bu
+Specifying a filename containing a slash as an argument to the
+.B \-p
+option to the
+.B hash
+builtin command
+.IP \(bu
importing function definitions from the shell environment at startup
.IP \(bu
parsing the value of \fBSHELLOPTS\fP from the shell environment at startup
.B enable
builtin command
.IP \(bu
+Using the \fBenable\fP builtin command to enable disabled shell builtins
+.IP \(bu
specifying the
.B \-p
option to the
.PP
These restrictions are enforced after any startup files are read.
.PP
-When a command that is found to be a shell script is executed (see
+.ie \n(zY=1 When a command that is found to be a shell script is executed,
+.el \{ When a command that is found to be a shell script is executed
+(see
.SM
.B "COMMAND EXECUTION"
above),
+\}
.B rbash
turns off any restrictions in the shell spawned to execute the
script.
+.\" end of rbash.1
+.if \n(zY=1 .ig zY
.SH "SEE ALSO"
.PD 0
.TP
-\fIBash Features\fP, Brian Fox and Chet Ramey
+\fIBash Reference Manual\fP, Brian Fox and Chet Ramey
.TP
\fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
.TP
.FN ~/.bashrc
The individual per-interactive-shell startup file
.TP
+.FN ~/.bash_logout
+The individual login shell cleanup file, executed when a login shell exits
+.TP
.FN ~/.inputrc
Individual \fIreadline\fP initialization file
.PD
.SH AUTHORS
Brian Fox, Free Software Foundation
.br
-bfox@gnu.ai.MIT.Edu
+bfox@gnu.org
.PP
Chet Ramey, Case Western Reserve University
.br
-chet@ins.CWRU.Edu
+chet@po.cwru.edu
.SH BUG REPORTS
If you find a bug in
.B bash,
you should report it. But first, you should
make sure that it really is a bug, and that it appears in the latest
version of
-.B bash
-that you have.
+.BR bash .
+The latest version is always available from
+\fIftp://ftp.gnu.org/pub/bash/\fP.
.PP
Once you have determined that a bug actually exists, use the
.I bashbug
.PP
Comments and bug reports concerning
this manual page should be directed to
-.IR chet@ins.CWRU.Edu .
+.IR chet@po.cwru.edu .
.SH BUGS
.PP
It's too big and too slow.
parentheses to force it into a subshell, which may be stopped as
a unit.
.PP
-Commands inside of \fB$(\fP...\fB)\fP command substitution are not
-parsed until substitution is attempted. This will delay error
-reporting until some time after the command is entered.
-.PP
Array variables may not (yet) be exported.
+.PP
+There may be only one active coprocess at a time.
.zZ
+.zY
projects / platform / upstream / bash.git / blobdiff