.\" MAN PAGE COMMENTS to
.\"
.\" Chet Ramey
-.\" Information Network Services
.\" Case Western Reserve University
-.\" chet@ins.CWRU.Edu
+.\" chet@po.cwru.edu
.\"
-.\" Last Change: Mon Mar 5 10:19:14 EST 2001
+.\" Last Change: Mon Dec 29 16:49:01 EST 2008
.\"
.\" bash_builtins, strip all but Built-Ins section
.if \n(zZ=1 .ig zZ
.if \n(zY=1 .ig zY
-.TH BASH 1 "2001 Mar 5" "GNU Bash-2.05"
+.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) 1989-2001 by the Free Software Foundation, Inc.
-.if t Bash is Copyright \(co 1989-2001 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 \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
-.PD 0
\fB\-\-init\-file\fP \fIfile\fP
+.PD 0
.TP
\fB\-\-rcfile\fP \fIfile\fP
.PD
below).
.TP
.B \-\-login
-Make
-.B bash
-act as if it had been invoked as a login shell (see
-.SM
-.B INVOCATION
-below).
+Equivalent to \fB\-l\fP.
.TP
.B \-\-noediting
Do not use the GNU
.TP
.B \-\-posix
Change the behavior of \fBbash\fP where the default operation differs
-from the POSIX 1003.2 standard to match the standard (\fIposix mode\fP).
+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 \- ,
and without the
.B \-c
option
-whose standard input and output are
+whose standard input and error are
both connected to terminals (as determined by
.IR isatty (3)),
or one started with the
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
.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 \fBSHELLOPTS\fP variable, if it appears in the environment, is ignored,
+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.
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
.I command2
is executed if and only if
.I command1
-returns a non-zero exit status. The return status of
+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
The list of words following \fBin\fP is expanded, generating a list
.I list
is executed after each selection until a
.B break
-or
-.B return
command is executed.
The exit status of
.B select
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.)
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, the
+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
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
.B \e\e
backslash
.TP
-.B \e'
+.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
.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
.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.
-Assignments to
-.SM
-.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 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${COMP_WORDS}\fP of the word containing the current
+cursor position.
+This variable is available only in shell functions invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
.TP
-.B SECONDS
-Each time this parameter is
-referenced, the number of seconds since shell invocation is returned. If a
-value is assigned to
-.SM
-.BR SECONDS ,
-the value returned upon subsequent
-references is
-the number of seconds since the assignment plus the value assigned.
+.B COMP_KEY
+The key (or final key of a key sequence) used to invoke the current
+completion function.
+.TP
+.B COMP_LINE
+The current command line.
+This variable is available only in shell functions and external
+commands invoked by the
+programmable completion facilities (see \fBProgrammable Completion\fP
+below).
+.TP
+.B COMP_POINT
+The index of the current cursor position relative to the beginning of
+the current command.
+If the current cursor position is at the end of the current command,
+the value of this variable is equal to \fB${#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 SECONDS
+.B COMP_WORDBREAKS
is unset, it loses its special properties, even if it is
subsequently reset.
.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.
+.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
+below) containing the current contents of the directory stack.
+Directories appear in the stack in the order they are displayed by the
+.B dirs
+builtin.
+Assigning to members of this array variable may be used to modify
+directories already in the stack, but the
+.B pushd
+and
+.B popd
+builtins must be used to add and remove directories.
+Assignment to this variable will not change the current directory.
If
.SM
-.B LINENO
+.B DIRSTACK
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.
+.B EUID
+Expands to the effective user ID of the current user, initialized at
+shell startup. This variable is readonly.
.TP
.B FUNCNAME
-The name of any currently-executing shell function.
+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
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
-.B DIRSTACK
-An array variable (see
-.B Arrays
-below) containing the current contents of the directory stack.
-Directories appear in the stack in the order they are displayed by the
-.B dirs
-builtin.
-Assigning to members of this array variable may be used to modify
-directories already in the stack, but the
-.B pushd
-and
-.B popd
-builtins must be used to add and remove directories.
-Assignment to this variable will not change the current directory.
+.B GROUPS
+An array variable containing the list of groups of which the current
+user is a member.
+Assignments to
+.SM
+.B GROUPS
+have no effect and return an error status.
If
.SM
-.B DIRSTACK
+.B GROUPS
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 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.
+.TP
+.B HOSTTYPE
+Automatically set to a string that uniquely
+describes the type of machine on which
+.B bash
+is executing.
+The default is system-dependent.
+.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.
+.TP
+.B MACHTYPE
+Automatically set to a string that fully describes the system
+type on which
+.B bash
+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 SHELL BUILTIN COMMANDS
below).
.TP
-.B HOSTNAME
-Automatically set to the name of the current host.
-.TP
-.B HOSTTYPE
-Automatically set to a string that uniquely
-describes the type of machine on which
-.B bash
-is executing.
-The default is system-dependent.
-.TP
.B OSTYPE
Automatically set to a string that
describes the operating system on which
is executing.
The default is system-dependent.
.TP
-.B MACHTYPE
-Automatically set to a string that fully describes the system
-type on which
-.B bash
-is executing, in the standard GNU \fIcpu-company-system\fP format.
-The default is system-dependent.
+.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
reading any startup files.
This variable is read-only.
.TP
-.B COMP_WORDS
-An array variable (see \fBArrays\fP below) consisting of the individual
-words in the current command line.
-This variable is available only in shell functions invoked by the
-programmable completion facilities (see \fBProgrammable Completion\fP
-below).
-.TP
-.B COMP_CWORD
-An index into \fB${COMP_WORDS}\fP of the word containing the current
-cursor position.
-This variable is available only in shell functions invoked by the
-programmable completion facilities (see \fBProgrammable Completion\fP
-below).
-.TP
-.B COMP_LINE
-The current command line.
-This variable is available only in shell functions and external
-commands invoked by the
-programmable completion facilities (see \fBProgrammable Completion\fP
-below).
+.B SHLVL
+Incremented by one each time an instance of
+.B bash
+is started.
.TP
-.B COMP_POINT
-The index of the current cursor position relative to the beginning of
-the current command.
-If the current cursor position is at the end of the current command,
-the value of this variable is equal to \fB${#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).
+.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
-.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 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, or set to a value that is not a number
-greater than or equal to zero, 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 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$_\fP expands to the name of
-the current mailfile.
-Example:
-.RS
-.PP
-\fBMAILPATH\fP='/var/mail/bfox?"You have mail":~/shell\-mail?"$_ 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., /var/mail/\fB$USER\fP).
-.RE
+.B COLUMNS
+Used by the \fBselect\fP builtin command to determine the terminal width
+when printing selection lists. Automatically set upon receipt of a SIGWINCH.
.TP
-.B PS1
-The value of this parameter is expanded (see
-.SM
-.B PROMPTING
-below) and used as the primary prompt string. The default value is
-``\fB\es\-\ev\e$ \fP''.
+.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 PS2
-The value of this parameter is expanded as with
-.B PS1
-and used as the secondary prompt string. The default is
-``\fB> \fP''.
+.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 PS3
-The value of this parameter is used as the prompt for the
-.B select
-command (see
-.SM
-.B SHELL GRAMMAR
-above).
+.B FCEDIT
+The default editor for the
+.B fc
+builtin command.
.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 FIGNORE
+A colon-separated list of suffixes to ignore when performing
+filename completion (see
.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.
+.B READLINE
+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
+.if t \f(CW".o:~"\fP.
+.if n ".o:~".
.TP
-.B HISTSIZE
-The number of commands to remember in the command history (see
+.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 HISTORY
-below). The default value is 500.
+.BR GLOBIGNORE ,
+it is removed from the list of matches.
+.TP
+.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
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 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 PROMPT_COMMAND
-If set, the value is executed as a command prior to issuing each primary
-prompt.
-.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 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 Bash
-terminates after waiting for that number of seconds if input does
-not arrive.
+.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 FCEDIT
-The default editor for the
-.B fc
-builtin command.
+.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
+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 FIGNORE
-A colon-separated list of suffixes to ignore when performing
-filename completion (see
+.B OPTERR
+If set to the value 1,
+.B bash
+displays error messages generated by the
+.B getopts
+builtin command (see
.SM
-.B READLINE
+.B SHELL BUILTIN COMMANDS
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:~''.
-.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
.SM
-.BR GLOBIGNORE ,
-it is removed from the list of matches.
+.B OPTERR
+is initialized to 1 each time the shell is invoked or a shell
+script is executed.
.TP
-.B INPUTRC
-The filename for the
-.B readline
-startup file, overriding the default of
-.FN ~/.inputrc
-(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 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 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 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 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 .
+.B PROMPT_COMMAND
+If set, the value is executed as a command prior to issuing each primary
+prompt.
.TP
-.B histchars
-The two or three characters which control history expansion
-and tokenization (see
+.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
-.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.
+.B PROMPTING
+below). Characters removed are replaced with an ellipsis.
.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
-adds the contents of the new file to the existing list.
-If
+.B PS1
+The value of this parameter is expanded (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
.SM
-.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
+.B SHELL GRAMMAR
+above).
+.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
.SM
-.B HOSTFILE
-is unset, the hostname list is cleared.
+.B PS4
+is replicated multiple times, as necessary, to indicate multiple
+levels of indirection. The default is ``\fB+ \fP''.
+.TP
+.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
+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 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).
+.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 \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.
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
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 exception to this is the expansion of ${!\fIprefix\fP*}
-described below.
+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
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 the expanded value of \fIparameter\fP.
If \fIpattern\fP begins with \fB%\fP, it must match at the end
.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
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
parameters that have no values, are removed.
If a parameter with no value is expanded within double quotes, a
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.
.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
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
.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, \fBbash\fP attempts to open a TCP connection
-to the corresponding socket.
+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, \fBbash\fP attempts to open a UDP connection
-to the corresponding socket.
+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
.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
.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
.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" ,
during its execution.
The special parameter
.B #
-is updated to reflect the change. Positional parameter 0
+is updated to reflect the change. Special parameter 0
is unchanged.
-The
+The first element of the
.SM
.B FUNCNAME
variable is set to the name of the function while the function
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 and associativity are the same
-as in the C language.
+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.
logical OR
.TP
.B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP
-conditional evaluation
+conditional operator
.TP
.B = *= /= %= += \-= <<= >>= &= ^= |=
assignment
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.
+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
base, and \fIn\fP is a number in that base.
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
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
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.
.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
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.
.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
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 \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
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
.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 readline
.B insert\-comment
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
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
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
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.
alphanumeric characters (letters and digits).
.TP
.B backward\-word (M\-b)
-Move back to the start of the current or 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.
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
.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. By default, this is not bound to a key.
+deleted.
.TP
.B quoted\-insert (C\-q, C\-v)
Add the next character typed to the line verbatim. This is
.B transpose\-words (M\-t)
Drag the word before point past the word after point,
moving point over that word as well.
+If point is at the end of the line, this transposes
+the last two words on the line.
.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
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 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
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
-(subject to the setting of \Bbell\-style\fP)
+(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
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 insert the list of possible completions
enclosed within braces so the list is available to the shell (see
character. A negative count searches for subsequent occurrences.
.TP
.B insert\-comment (M\-#)
-The value of the 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. The default value of
+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
Shell quoting is honored.
Each word is then expanded using
brace expansion, tilde expansion, parameter and variable expansion,
-command substitution, arithmetic expansion, and pathname expansion,
+command substitution, and arithmetic expansion,
as described above under
.SM
.BR EXPANSION .
specified with the \fB\-F\fP and \fB\-C\fP options is invoked.
When the command or function is invoked, the
.SM
-.B COMP_LINE
+.BR COMP_LINE ,
+.SM
+.BR COMP_POINT ,
+.SM
+.BR COMP_KEY ,
and
.SM
-.B COMP_POINT
+.B COMP_TYPE
variables are assigned values as described above under
\fBShell Variables\fP.
If a shell function is being invoked, 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 default\fP option was supplied to \fBcomplete\fP when the
-compspec was defined, readline's default completion will be performed
+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
the number of lines specified by the value of
.SM
.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
.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
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
\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\-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. The binding syntax accepted is identical to that of
+function or macro, or set a
+.B readline
+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
.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
.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
The return value is true unless an invalid option is supplied, or no
matches were generated.
.TP
-.PD 0
-\fBcomplete\fP [\fB\-abcdefjkvu\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP]
+\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\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP] \fIname\fP [\fIname ...\fP]
+[\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 [\fIname\fP ...]
+\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,
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.
\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 completion if the compspec generates no matches.
+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 or
-suppressing trailing spaces). Intended to be used with shell functions.
+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
.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 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
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,
+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,
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
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 without specifying a full pathname,
If the
.B \-l
option is supplied,
-the shell places a dash at the beginning of 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
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''
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 [\fB\-s\fP] [\fIpattern\fP]
+\fBhelp\fP [\fB\-dms\fP] [\fIpattern\fP]
Display helpful information about builtin commands. If
.I pattern
is specified,
.IR pattern ;
otherwise help for all the builtins and shell control structures
is printed.
-The \fB\-s\fP option restricts the information displayed to a short
-usage synopsis.
+.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
-.PD 0
\fBhistory [\fIn\fP]
+.PD 0
.TP
\fBhistory\fP \fB\-c\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
are added.
.PD
.PP
+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 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
.if n ``popd -1''
.if t \f(CWpopd -1\fP
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.
.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. 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
.I dir
Adds
.I dir
reading the name of the current directory or an
invalid option is supplied.
.TP
-\fBread\fP [\fB\-ers\fP] [\fB\-t\fP \fItimeout\fP] [\fB\-a\fP \fIaname\fP] [\fB\-p\fP \fIprompt\fP] [\fB\-n\fP \fInchars\fP] [\fB\-d\fP \fIdelim\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
.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, without a
+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 \-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.
-This option has no effect if \fBread\fP is not reading input from the
-terminal or a pipe.
+\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 or \fBread\fP
-times out.
+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
.B \-p
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\-\-abefhkmnptuvxBCEHPT\fP] [\fB\-o\fP \fIoption\fP] [\fIarg\fP ...]
+.PD 0
.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
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 and functions 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
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 (\fIposix mode\fP).
+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
files are not processed, shell functions are not inherited from the
environment, and the
.SM
-.B SHELLOPTS
-variable, if it appears in the environment, is ignored.
+.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.
.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
.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
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.
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
.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
.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]
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.
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
.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.
.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