.\" Case Western Reserve University
.\" chet@po.cwru.edu
.\"
-.\" Last Change: Mon Dec 29 16:49:01 EST 2008
+.\" Last Change: Tue Dec 28 13:41:43 EST 2010
.\"
.\" bash_builtins, strip all but Built-Ins section
.if \n(zZ=1 .ig zZ
.if \n(zY=1 .ig zY
-.TH BASH 1 "2008 December 29" "GNU Bash-4.0"
+.TH BASH 1 "2010 December 28" "GNU Bash-4.2"
.\"
.\" 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) 1989-2009 by the Free Software Foundation, Inc.
-.if t Bash is Copyright \(co 1989-2009 by the Free Software Foundation, Inc.
+.if n Bash is Copyright (C) 1989-2011 by the Free Software Foundation, Inc.
+.if t Bash is Copyright \(co 1989-2011 by the Free Software Foundation, Inc.
.SH DESCRIPTION
.B Bash
is an \fBsh\fR-compatible command language interpreter that
.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
+All of the single-character shell options documented in the
+description of the \fBset\fR builtin command can be used as options
+when the shell is invoked.
+In addition, \fBbash\fR
interprets the following options when it is invoked:
.PP
.PD 0
.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
.PP
.B Bash
attempts to determine when it is being run with its standard input
-connected to a a network connection, as if by the remote shell
+connected to a network connection, as when executed by the remote shell
daemon, usually \fIrshd\fP, or the secure shell daemon \fIsshd\fP.
If
.B bash
real user (group) id, and the \fB\-p\fP option is not supplied, no startup
files are read, shell functions are not inherited from the environment, the
.SM
-.B SHELLOPTS
-variable, if it appears in the environment, is ignored,
+.BR SHELLOPTS ,
+.SM
+.BR BASHOPTS ,
+.SM
+.BR CDPATH ,
+and
+.SM
+.B GLOBIGNORE
+variables, if they appear in the environment, are 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 t \fB|| & && ; ;; ( ) | |& <newline>\fP
.if n \fB|| & && ; ;; ( ) | |& <newline>\fP
.RE
.PD
system time consumed by its execution are reported when the pipeline
terminates.
The \fB\-p\fP option changes the output format to that specified by POSIX.
+When the shell is in \fIposix mode\fP, it does not recognize
+\fBtime\fP as a reserved word if the next token begins with a `-'.
The
.SM
.B TIMEFORMAT
.B "Shell Variables"
below.
.PP
+When the shell is in \fIposix mode\fP, \fBtime\fP
+may be followed by a newline. In this case, the shell displays the
+total user and system time consumed by the shell and its children.
+The
+.SM
+.B TIMEFORMAT
+variable may be used to specify the format of
+the time information.
+.PP
Each command in a pipeline is executed as a separate process (i.e., in a
subshell).
.SS Lists
.BR & ,
.BR && ,
or
-.BR \(bv\(bv ,
+.BR || ,
and optionally terminated by one of
.BR ; ,
.BR & ,
Of these list operators,
.B &&
and
-.B \(bv\(bv
+.B ||
have equal precedence, followed by
.B ;
and
exit status of the last command executed.
.PP
AND and OR lists are sequences of one of more pipelines separated by the
-\fB&&\fP and \fB\(bv\(bv\fP control operators, respectively.
+\fB&&\fP and \fB||\fP control operators, respectively.
AND and OR lists are executed with left associativity.
An AND list has the form
.RS
An OR list has the form
.RS
.PP
-\fIcommand1\fP \fB\(bv\(bv\fP \fIcommand2\fP
+\fIcommand1\fP \fB||\fP \fIcommand2\fP
.PP
.RE
.PP
as primaries.
.if t .sp 0.5
.if n .sp 1
+When used with \fB[[\fP, the \fB<\fP and \fB>\fP operators sort
+lexicographically using the current locale.
+.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.
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
+expression are saved in the array variable
+.SM
+.BR BASH_REMATCH .
+The element of
+.SM
+.B BASH_REMATCH
+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
+The element of
+.SM
+.B BASH_REMATCH
+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
.I expression2
are true.
.TP
-.if t \fIexpression1\fP \fB\(bv\(bv\fP \fIexpression2\fP
-.if n \fIexpression1\fP \fB||\fP \fIexpression2\fP
+\fIexpression1\fP \fB||\fP \fIexpression2\fP
True if either
.I expression1
or
is true.
.PD
.LP
-The \fB&&\fP and
-.if t \fB\(bv\(bv\fP
-.if n \fB||\fP
+The \fB&&\fP and \fB||\fP
operators do not evaluate \fIexpression2\fP if the value of
\fIexpression1\fP is sufficient to determine the return value of
the entire conditional expression.
.RE
.TP
-\fBfor\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP
+\fBfor\fP \fIname\fP [ [ \fBin\fP [ \fIword ...\fP ] ] ; ] \fBdo\fP \fIlist\fP ; \fBdone\fP
The list of words following \fBin\fP is expanded, generating a list
of items.
The variable \fIname\fP is set to each element of this list
.SM
.B PARAMETERS
below). The
+.SM
.B PS3
prompt is then displayed and a line read from the standard input.
If the line consists of a number corresponding to one of
other value read causes
.I name
to be set to null. The line read is saved in the variable
+.SM
.BR REPLY .
The
.I list
executed, if present. The exit status is the exit status of the
last command executed, or zero if no condition tested true.
.TP
-\fBwhile\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP
+\fBwhile\fP \fIlist-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP
.PD 0
.TP
-\fBuntil\fP \fIlist\fP; \fBdo\fP \fIlist\fP; \fBdone\fP
+\fBuntil\fP \fIlist-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP
.PD
-The \fBwhile\fP command continuously executes the \fBdo\fP
-\fIlist\fP as long as the last command in \fIlist\fP returns
+The \fBwhile\fP command continuously executes the list
+\fIlist-2\fP as long as the last command in the list \fIlist-1\fP returns
an exit status of zero. The \fBuntil\fP command is identical
to the \fBwhile\fP command, except that the test is negated;
-the
-.B do
-.I list
+.I list-2
is executed as long as the last command in
-.I list
+.I list-1
returns a non-zero exit status.
The exit status of the \fBwhile\fP and \fBuntil\fP commands
is the exit status
-of the last \fBdo\fP \fIlist\fP command executed, or zero if
+of the last command executed in \fIlist-2\fP, or zero if
none was executed.
.SS Coprocesses
.PP
.PP
This creates a coprocess named \fINAME\fP.
If \fINAME\fP is not supplied, the default name is \fICOPROC\fP.
+\fINAME\fP must not be supplied if \fIcommand\fP is a \fIsimple
+command\fP (see above); otherwise, it is interpreted as the first word
+of the simple command.
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.
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
+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.
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]
+\fIname\fP () \fIcompound\-command\fP [\fIredirection\fP]
+.PD 0
+.TP
+\fBfunction\fP \fIname\fP [()] \fIcompound\-command\fP [\fIredirection\fP]
+.PD
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.
backspace
.TP
.B \ee
+.TP
+.B \eE
an escape character
.TP
.B \ef
.TP
.B \e\(aq
single quote
+.TP
+.B \e\(dq
+double quote
.TP
.B \e\fInnn\fP
the eight-bit character whose value is the octal value \fInnn\fP
the eight-bit character whose value is the hexadecimal value \fIHH\fP
(one or two hex digits)
.TP
+.B \eu\fIHHHH\fP
+the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
+\fIHHHH\fP (one to four hex digits)
+.TP
+.B \eU\fIHHHHHHHH\fP
+the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
+\fIHHHHHHHH\fP (one to eight hex digits)
+.TP
.B \ec\fIx\fP
a control-\fIx\fP character
.PD
The expanded result is single-quoted, as if the dollar sign had
not been present.
.PP
-A double-quoted string preceded by a dollar sign (\fB$\fP) will cause
-the string to be translated according to the current locale.
+A double-quoted string preceded by a dollar sign (\fB$\fP\(dq\fIstring\fP\(dq)
+will cause the string to be translated according to the current locale.
If the current locale is \fBC\fP or \fBPOSIX\fP, the dollar sign
is ignored.
If the string is translated and replaced, the replacement is
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
+When += is applied to a variable for which the \fIinteger\fP 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
Expands to the full file name used to invoke this instance of
.BR bash .
.TP
+.B BASHOPTS
+A colon-separated list of enabled shell options. Each word in
+the list is a valid argument for the
+.B \-s
+option to the
+.B shopt
+builtin command (see
+.SM
+.B "SHELL BUILTIN COMMANDS"
+below). The options appearing in
+.SM
+.B BASHOPTS
+are those reported as
+.I on
+by \fBshopt\fP.
+If this variable is in the environment when
+.B bash
+starts up, each shell option in the list will be enabled before
+reading any startup files.
+This variable is read-only.
+.TP
.B BASHPID
-Expands to the process id of the current \fBbash\fP process.
+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
+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
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
+.SM
+.BR BASH_ARGC .
+The shell sets
+.SM
+.B BASH_ARGC
+only when in extended debugging mode (see the description of the
.B extdebug
option to the
.B shopt
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
+are pushed onto
+.SM
+.BR BASH_ARGV .
+The shell sets
+.SM
+.B BASH_ARGV
+only when in extended debugging mode
(see the description of the
.B extdebug
option to the
.TP
.B BASH_LINENO
An array variable whose members are the line numbers in source files
-corresponding to each member of \fBFUNCNAME\fP.
+where each corresponding member of
+.SM
+.B FUNCNAME
+was invoked.
\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
+file (\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP) 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.
+Use
+.SM
+.B LINENO
+to obtain the current line number.
.TP
.B BASH_REMATCH
An array variable whose members are assigned by the \fB=~\fP binary
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.
+An array variable whose members are the source filenames
+where the corresponding shell function names in the
+.SM
+.B FUNCNAME
+array variable are defined.
+The shell function
+\fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP is defined in the file
+\fB${BASH_SOURCE[\fP\fI$i\fP\fB]}\fP and called from
+\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP.
.TP
.B BASH_SUBSHELL
Incremented by one each time a subshell or subshell environment is spawned.
The values assigned to the array members are as follows:
.sp .5
.RS
-.PD 0
.TP 24
.B BASH_VERSINFO[\fR0\fP]
The major version number (the \fIrelease\fP).
The release status (e.g., \fIbeta1\fP).
.TP
.B BASH_VERSINFO[\fR5\fP]
-The value of \fBMACHTYPE\fP.
-.PD
+The value of
+.SM
+.BR MACHTYPE .
.RE
.TP
.B BASH_VERSION
below).
.TP
.B COMP_WORDBREAKS
-The set of characters that the Readline library treats as word
+The set of characters that the \fBreadline\fP library treats as word
separators when performing word completion.
If
.SM
.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.
+The line is split into words as \fBreadline\fP would split it, using
+.SM
+.B COMP_WORDBREAKS
+as described above.
This variable is available only in shell functions invoked by the
programmable completion facilities (see \fBProgrammable Completion\fP
below).
.TP
+.B COPROC
+An array variable (see \fBArrays\fP below) created to hold the file descriptors
+for output from and input to an unnamed coprocess (see \fBCoprocesses\fP
+above).
+.TP
.B DIRSTACK
An array variable (see
.B Arrays
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
+The bottom-most element (the one with the highest index) is
.if t \f(CW"main"\fP.
.if n "main".
This variable exists only when a shell function is executing.
.B FUNCNAME
is unset, it loses its special properties, even if it is
subsequently reset.
+.if t .sp 0.5
+.if n .sp 1
+This variable can be used with \fBBASH_LINENO\fP and \fBBASH_SOURCE\fP.
+Each element of \fBFUNCNAME\fP has corresponding elements in
+\fBBASH_LINENO\fP and \fBBASH_SOURCE\fP to describe the call stack.
+For instance, \fB${FUNCNAME[\fP\fI$i\fP\fB]}\fP was called from the file
+\fB${BASH_SOURCE[\fP\fI$i+1\fP\fB]}\fP at line number
+\fB${BASH_LINENO[\fP\fI$i\fP\fB]}\fP.
+The \fBcaller\fP builtin displays the current call stack using this
+information.
.TP
.B GROUPS
An array variable containing the list of groups of which the current
is executing, in the standard GNU \fIcpu-company-system\fP format.
The default is system-dependent.
.TP
+.B MAPFILE
+An array variable (see \fBArrays\fP below) created to hold the text
+read by the \fBmapfile\fP builtin when no variable name is supplied.
+.TP
.B OLDPWD
The previous working directory as set by the
.B cd
is unset, it loses its special properties, even if it is
subsequently reset.
.TP
+.B READLINE_LINE
+The contents of the
+.B readline
+line buffer, for use with
+.if t \f(CWbind -x\fP
+.if n "bind -x"
+(see
+.SM
+.B "SHELL BUILTIN COMMANDS"
+below).
+.TP
+.B READLINE_POINT
+The position of the insertion point in the
+.B readline
+line buffer, for use with
+.if t \f(CWbind -x\fP
+.if n "bind -x"
+(see
+.SM
+.B "SHELL BUILTIN COMMANDS"
+below).
+.TP
.B REPLY
Set to the line of input read by the
.B read
.B PATH
is not used to search for the resultant file name.
.TP
+.B BASH_XTRACEFD
+If set to an integer corresponding to a valid file descriptor, \fBbash\fP
+will write the trace output generated when
+.if t \f(CWset -x\fP
+.if n \fIset -x\fP
+is enabled to that file descriptor.
+The file descriptor is closed when
+.SM
+.B BASH_XTRACEFD
+is unset or assigned a new value.
+Unsetting
+.SM
+.B BASH_XTRACEFD
+or assigning it the empty string causes the
+trace output to be sent to the standard error.
+Note that setting
+.SM
+.B BASH_XTRACEFD
+to 2 (the standard error file
+descriptor) and then unsetting it will result in the standard error
+being closed.
+.TP
.B CDPATH
The search path for the
.B cd
.if n ".:~:/usr".
.TP
.B COLUMNS
-Used by the \fBselect\fP builtin command to determine the terminal width
-when printing selection lists. Automatically set upon receipt of a SIGWINCH.
+Used by the \fBselect\fP compound command to determine the terminal width
+when printing selection lists. Automatically set upon receipt of a
+.SM
+.BR SIGWINCH .
.TP
.B COMPREPLY
An array variable from which \fBbash\fP reads the possible completions
with value
.if t \f(CWt\fP,
.if n "t",
-it assumes that the shell is running in an emacs shell buffer and disables
+it assumes that the shell is running in an Emacs shell buffer and disables
line editing.
.TP
+.B ENV
+Similar to
+.SM
+.BR BASH_ENV ;
+used when the shell is invoked in POSIX mode.
+.TP
.B FCEDIT
The default editor for the
.B fc
.if t \f(CW".o:~"\fP.
.if n ".o:~".
.TP
+.B FUNCNEST
+If set to a numeric value greater than 0, defines a maximum function
+nesting level. Function invocations that exceed this nesting level
+will cause the current command to abort.
+.TP
.B GLOBIGNORE
A colon-separated list of patterns defining the set of filenames to
be ignored by pathname expansion.
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,
+If
+.SM
+.B HISTCONTROL
+is unset, or does not include a valid value,
all lines read by the shell parser are saved on the history list,
subject to the value of
+.SM
.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
+.SM
.BR HISTCONTROL .
.TP
.B HISTFILE
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
+.SM
.B HISTCONTROL
are applied.
In addition to the normal shell pattern matching characters, `\fB&\fP'
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
+.SM
.BR HISTIGNORE .
.TP
.B HISTSIZE
If
.SM
.B HOSTFILE
-is set, but has no value, \fBbash\fP attempts to read
+is set, but has no value, or does not name a readable file,
+\fBbash\fP attempts to read
.FN /etc/hosts
to obtain the list of possible hostname completions.
When
selected with a variable starting with \fBLC_\fP.
.TP
.B LC_ALL
-This variable overrides the value of \fBLANG\fP and any other
+This variable overrides the value of
+.SM
+.B LANG
+and any other
\fBLC_\fP variable specifying a locale category.
.TP
.B LC_COLLATE
This variable determines the locale category used for number formatting.
.TP
.B LINES
-Used by the \fBselect\fP builtin command to determine the column length
-for printing selection lists. Automatically set upon receipt of a SIGWINCH.
+Used by the \fBselect\fP compound command to determine the column length
+for printing selection lists. Automatically set upon receipt of a
+.SM
+.BR SIGWINCH .
.TP
.B MAIL
-If this parameter is set to a file name and the
+If this parameter is set to a file or directory name and the
.SM
.B MAILPATH
variable is not set,
.B bash
-informs the user of the arrival of mail in the specified file.
+informs the user of the arrival of mail in the specified file or
+Maildir-format directory.
.TP
.B MAILCHECK
Specifies how
.SM
.B COMMAND EXECUTION
below).
-A zero-length (null) directory name in the value of \fBPATH\fP indicates the
-current directory.
+A zero-length (null) directory name in the value of
+.SM
+.B PATH
+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,
.TP
.B PROMPT_DIRTRIM
If set to a number greater than zero, the value is used as the number of
-trailing directory components to retain when expanding the \fB\ew\fB and
+trailing directory components to retain when expanding the \fB\ew\fP and
\fB\eW\fP prompt string escapes (see
.SM
.B PROMPTING
.TP
.B PS2
The value of this parameter is expanded as with
+.SM
.B PS1
and used as the secondary prompt string. The default is
``\fB> \fP''.
.TP
.B PS4
The value of this parameter is expanded as with
+.SM
.B PS1
and the value is printed before each command
.B bash
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.
+.PD 0
.TP
.B TMOUT
-If set to a value greater than zero, \fBTMOUT\fP is treated as the
+If set to a value greater than zero,
+.SM
+.B TMOUT
+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.
+after
+.SM
+.B TMOUT
+seconds when input is coming from a terminal.
In an interactive shell, the value is interpreted as the
number of seconds to wait for input after issuing the primary prompt.
.B Bash
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.
+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
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 indexed array,
-use
+is treated as an arithmetic expression that must evaluate to a number.
+If
+.I subscript
+evaluates to a number less than zero, it is used as
+an offset from one greater than the array's maximum index (so a subcript
+of -1 refers to the last element of the array).
+To explicitly declare an indexed array, use
.B declare \-a \fIname\fP
(see
.SM
Referencing an array variable without a subscript is equivalent to
referencing the array with a subscript of 0.
.PP
+An array variable is considered set if a subscript has been assigned a
+value. The null string is a valid value.
+.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.
+Care must be taken to avoid unwanted side effects caused by pathname
+expansion.
\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.
option to specify an indexed array and a
.B \-A
option to specify an associative array.
+If both options are supplied,
+.B \-A
+takes precedence.
The
.B read
builtin accepts a
interpreted as part of its name.
.PD
.PP
-If the first character of \fIparameter\fP is an exclamation point,
+If the first character of \fIparameter\fP is an exclamation point (\fB!\fP),
a level of variable indirection is introduced.
\fBBash\fP uses the value of the variable formed from the rest of
\fIparameter\fP as the name of the variable; this variable is then
expanded and that value is used in the rest of the substitution, rather
than the value of \fIparameter\fP itself.
This is known as \fIindirect expansion\fP.
-The exceptions to this are the expansions of ${!\fIprefix\fP*} and
+The exceptions to this are the expansions of ${\fB!\fP\fIprefix\fP\fB*\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.
-When not performing substring expansion, \fBbash\fP tests for a parameter
-that is unset or null; omitting the colon results in a test only for a
-parameter that is unset.
+.PP
+When not performing substring expansion, using the forms documented below,
+\fBbash\fP tests for a parameter that is unset or null. Omitting the colon
+results in a test only for a parameter that is unset.
.PP
.PD 0
.TP
.TP
${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP}
.PD
-\fBSubstring Expansion.\fP
+\fBSubstring Expansion\fP.
Expands to up to \fIlength\fP characters of \fIparameter\fP
starting at the character specified by \fIoffset\fP.
If \fIlength\fP is omitted, expands to the substring of
.B
ARITHMETIC EVALUATION
below).
-\fIlength\fP must evaluate to a number greater than or equal to zero.
If \fIoffset\fP evaluates to a number less than zero, the value
is used as an offset from the end of the value of \fIparameter\fP.
+If \fIlength\fP evaluates to a number less than zero, and \fIparameter\fP
+is not \fB@\fP and not an indexed or associative array, it is interpreted
+as an offset from the end of the value of \fIparameter\fP rather than
+a number of characters, and the expansion is the characters between the
+two offsets.
If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional
parameters beginning at \fIoffset\fP.
If \fIparameter\fP is an indexed array name subscripted by @ or *,
.TP
${\fB!\fP\fIprefix\fP\fB@\fP}
.PD
-\fBNames matching prefix.\fP
+\fBNames matching prefix\fP.
Expands to the names of variables whose names begin with \fIprefix\fP,
separated by the first character of the
.SM
.TP
${\fB!\fP\fIname\fP[\fI*\fP]}
.PD
-\fBList of array keys.\fP
+\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
key expands to a separate word.
.TP
${\fB#\fP\fIparameter\fP}
-\fBParameter length.\fP
+\fBParameter length\fP.
The length in characters of the value of \fIparameter\fP is substituted.
If
.I parameter
.TP
${\fIparameter\fP\fB##\fP\fIword\fP}
.PD
-\fBRemove matching prefix pattern.\fP
+\fBRemove matching prefix pattern\fP.
The
.I word
is expanded to produce a pattern just as in pathname
.TP
${\fIparameter\fP\fB%%\fP\fIword\fP}
.PD
-\fBRemove matching suffix pattern.\fP
+\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
array in turn, and the expansion is the resultant list.
.TP
${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP}
-\fBPattern substitution.\fP
+\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
.TP
${\fIparameter\fP\fB,,\fP\fIpattern\fP}
.PD
-\fBCase modification.\fP
+\fBCase modification\fP.
This expansion modifies the case of alphabetic characters in \fIparameter\fP.
The \fIpattern\fP is expanded to produce a pattern just as in
pathname expansion.
to lowercase.
The \fB^^\fP and \fB,,\fP expansions convert each matched character in the
expanded value; the \fB^\fP and \fB,\fP expansions match and convert only
-the first character.
+the first character in the expanded value.
If \fIpattern\fP is omitted, it is treated like a \fB?\fP, which matches
every character.
If
.PP
\fICommand substitution\fP allows the output of a command to replace
the command name. There are two forms:
-.PP
.RS
.PP
\fB$(\fP\fIcommand\fP\|\fB)\fP
The special pattern characters have the following meanings:
.PP
.PD 0
+.RS
.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
+a pathname 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
.B ^
then any character not enclosed is matched.
The sorting order of characters in range expressions is determined by
-the current locale and the value of the \fBLC_COLLATE\fP shell variable,
+the current locale and the value of the
+.SM
+.B LC_COLLATE
+shell variable,
if set.
A
.B \-
the syntax \fB[.\fP\fIsymbol\fP\fB.]\fP matches the collating symbol
\fIsymbol\fP.
.RE
+.RE
.PD
.PP
If the \fBextglob\fP shell option is enabled using the \fBshopt\fP
Redirections are processed in the order they appear, from
left to right.
.PP
+Each redirection that may be preceded by a file descriptor number
+may instead be preceded by a word of the form {\fIvarname\fP}.
+In this case, for each redirection operator except
+>&- and <&-, the shell will allocate a file descriptor greater
+than 10 and assign it to \fIvarname\fP. If >&- or <&- is preceded
+by {\fIvarname\fP}, the value of \fIvarname\fP defines the file
+descriptor to close.
+.PP
In the following descriptions, if the file descriptor number is
omitted, and the first character of the redirection operator is
.BR < ,
.PP
directs only the standard output to file
.IR dirlist ,
-because the standard error was duplicated as standard output
+because the standard error was duplicated from the standard output
before the standard output was redirected to
.IR dirlist .
.PP
during its execution.
The special parameter
.B #
-is updated to reflect the change. Special parameter 0
+is updated to reflect the change. Special parameter \fB0\fP
is unchanged.
The first element of the
.SM
.B FUNCNAME
variable is set to the name of the function while the function
is executing.
+.PP
All other aspects of the shell execution
environment are identical between a function and its caller
-with the exception that the
+with these exceptions: the
.SM
.B DEBUG
and
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).
+(in which case all functions inherit the \fBDEBUG\fP and \fBRETURN\fP traps),
+and the
+.SM
+.B ERR
+trap is not inherited unless the \fB\-o errtrace\fP shell option has
+been enabled.
.PP
Variables local to the function may be declared with the
.B local
builtin command. Ordinarily, variables and their values
are shared between the function and its caller.
.PP
+The \fBFUNCNEST\fP variable, if set to a numeric value greater
+than 0, defines a maximum function nesting level. Function
+invocations that exceed the limit cause the entire command to
+abort.
+.PP
If the builtin command
.B return
is executed in a function, the function completes and
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.
+Functions may be recursive.
+The \fBFUNCNEST\fP variable may be used to limit the depth of the
+function call stack and restrict the number of function invocations.
+By default, 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 and \fBdeclare\fP builtin
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
+A shell variable need not have its \fIinteger\fP attribute
turned on to be used in an expression.
.PP
Constants with a leading 0 are interpreted as octal numbers.
A leading 0x or 0X denotes hexadecimal.
-Otherwise, numbers take the form [\fIbase#\fP]n, where \fIbase\fP
+Otherwise, numbers take the form [\fIbase#\fP]n, where the optional \fIbase\fP
is a decimal number between 2 and 64 representing the arithmetic
base, and \fIn\fP is a number in that base.
If \fIbase#\fP is omitted, then base 10 is used.
.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.
+.if t .sp 0.5
+.if n .sp 1
+When used with \fB[[\fP, the \fB<\fP and \fB>\fP operators sort
+lexicographically using the current locale.
+The \fBtest\fP command sorts using ASCII ordering.
.sp 1
.PD 0
.TP
.B \-x \fIfile\fP
True if \fIfile\fP exists and is executable.
.TP
-.B \-O \fIfile\fP
-True if \fIfile\fP exists and is owned by the effective user id.
-.TP
.B \-G \fIfile\fP
True if \fIfile\fP exists and is owned by the effective group id.
.TP
.B \-L \fIfile\fP
True if \fIfile\fP exists and is a symbolic link.
.TP
+.B \-N \fIfile\fP
+True if \fIfile\fP exists and has been modified since it was last read.
+.TP
+.B \-O \fIfile\fP
+True if \fIfile\fP exists and is owned by the effective user id.
+.TP
.B \-S \fIfile\fP
True if \fIfile\fP exists and is a socket.
.TP
-.B \-N \fIfile\fP
-True if \fIfile\fP exists and has been modified since it was last read.
+\fIfile1\fP \fB\-ef\fP \fIfile2\fP
+True if \fIfile1\fP and \fIfile2\fP refer to the same device and
+inode numbers.
.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 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 refer to the same device and
-inode numbers.
-.TP
.B \-o \fIoptname\fP
-True if shell option
+True if the shell option
.I optname
is enabled.
See the list of options under the description of the
.B set
builtin below.
.TP
+.B \-v \fIvarname\fP
+True if the shell variable
+.I varname
+is set (has been assigned a value).
+.TP
.B \-z \fIstring\fP
True if the length of \fIstring\fP is zero.
.TP
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 for strict POSIX compliance.
+.PD 0
+.TP
+\fIstring1\fP \fB=\fP \fIstring2\fP
+.PD
+True if the strings are equal. \fB=\fP should be used
+with the \fBtest\fP command for POSIX conformance.
.TP
\fIstring1\fP \fB!=\fP \fIstring2\fP
True if the strings are not equal.
.TP
\fIstring1\fP \fB<\fP \fIstring2\fP
-True if \fIstring1\fP sorts before \fIstring2\fP lexicographically
-in the current locale.
+True if \fIstring1\fP sorts before \fIstring2\fP lexicographically.
.TP
\fIstring1\fP \fB>\fP \fIstring2\fP
-True if \fIstring1\fP sorts after \fIstring2\fP lexicographically
-in the current locale.
+True if \fIstring1\fP sorts after \fIstring2\fP lexicographically.
.TP
.I \fIarg1\fP \fBOP\fP \fIarg2\fP
.SM
.SH COMMAND EXECUTION ENVIRONMENT
The shell has an \fIexecution environment\fP, which consists of the
following:
-.sp 1
.IP \(bu
open files inherited by the shell at invocation, as modified by
redirections supplied to the \fBexec\fP builtin
shell aliases defined with \fBalias\fP
.IP \(bu
various process IDs, including those of background jobs, the value
-of \fB$$\fP, and the value of \fB$PPID\fP
+of \fB$$\fP, and the value of
+.SM
+.B PPID
.PP
When a simple command other than a builtin or shell function
is to be executed, it
is invoked in a separate execution environment that consists of
the following. Unless otherwise noted, the values are inherited
from the shell.
-.sp 1
+.if n .sp 1
.IP \(bu
the shell's open files, plus any modifications and additions specified
by redirections to the command
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.
+the \fB\-e\fP option from the parent shell. When not in \fIposix\fP mode,
+\fBbash\fP 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.
the execution of processes and continue (\fIresume\fP)
their execution at a later point. A user typically employs
this facility via an interactive interface supplied jointly
-by the system's terminal driver and
+by the operating system kernel's terminal driver and
.BR bash .
.PP
The shell associates a
.I Background
processes are those whose process group ID differs from the terminal's;
such processes are immune to keyboard-generated signals.
-Only foreground processes are allowed to read from or write to the
-terminal. Background processes which attempt to read from (write to) the
+Only foreground processes are allowed to read from or, if the
+user so specifies with \f(CWstty tostop\fP, write to the
+terminal.
+Background processes which attempt to read from (write to when
+\f(CWstty tostop\fP is in effect) the
terminal are sent a
.SM
.B SIGTTIN (SIGTTOU)
-signal by the terminal driver,
+signal by the kernel's terminal driver,
which, unless caught, suspends the process.
.PP
If the operating system on which
the release of \fBbash\fP, version + patch level (e.g., 2.00.0)
.TP
.B \ew
-the current working directory, with \fB$HOME\fP abbreviated with a tilde
-(uses the \fB$PROMPT_DIRTRIM\fP variable)
+the current working directory, with
+.SM
+.B $HOME
+abbreviated with a tilde
+(uses the value of the
+.SM
+.B PROMPT_DIRTRIM
+variable)
.TP
.B \eW
-the basename of the current working directory, with \fB$HOME\fP
+the basename of the current working directory, with
+.SM
+.B $HOME
abbreviated with a tilde
.TP
.B \e!
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.
+By default, the line editing commands are similar to those of Emacs.
A vi-style line editing interface is also available.
Line editing can be enabled at any time using the
.B \-o emacs
builtin.
.SS "Readline Notation"
.PP
-In this section, the emacs-style notation is used to denote
+In this section, the Emacs-style notation is used to denote
keystrokes. Control keys are denoted by C\-\fIkey\fR, e.g., C\-n
means Control\-N. Similarly,
.I meta
.TP
.B editing\-mode (emacs)
Controls whether readline begins with a set of key bindings similar
-to \fIemacs\fP or \fIvi\fP.
+to \fIEmacs\fP or \fIvi\fP.
.B editing\-mode
can be set to either
.B emacs
or
.BR vi .
.TP
+.B echo\-control\-characters (On)
+When set to \fBOn\fP, on operating systems that indicate they support it,
+readline echoes a character corresponding to a signal generated from the
+keyboard.
+.TP
.B enable\-keypad (Off)
When set to \fBOn\fP, readline will try to enable the application
keypad when it is called. Some systems need this to enable the
arrow keys.
.TP
+.B enable\-meta\-key (On)
+When set to \fBOn\fP, readline will try to enable any meta modifier
+key the terminal claims to support when it is called. On many terminals,
+the meta key is used to send eight-bit characters.
+.TP
.B expand\-tilde (Off)
-If set to \fBon\fP, tilde expansion is performed when readline
+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
+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 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
+completion.
+If set to \fBOff\fP, the leading `.' must be
supplied by the user in the filename to be completed.
.TP
+.B menu\-complete\-display\-prefix (Off)
+If set to \fBOn\fP, menu completion displays the common prefix of the
+list of possible completions (which may be empty) before cycling through
+the list.
+.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
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
+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.
.B show\-all\-if\-ambiguous (Off)
This alters the default behavior of the completion functions. If
set to
-.BR on ,
+.BR On ,
words which have more than one possible completion cause the
matches to be listed immediately instead of ringing the bell.
.TP
This alters the default behavior of the completion functions in
a fashion similar to \fBshow\-all\-if\-ambiguous\fP.
If set to
-.BR on ,
+.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 skip\-completed\-text (Off)
+If set to \fBOn\fP, this alters the default completion behavior when
+inserting a single match into the line. It's only active when
+performing completion in the middle of a word. If enabled, readline
+does not insert characters from the completion that match characters
+after point in the word being completed, so portions of the word
+following the cursor are not duplicated.
+.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
file can test for a particular value.
This could be used to bind key sequences to functions useful for
a specific program. For instance, the following command adds a
-key sequence that quotes the current or previous word in Bash:
+key sequence that quotes the current or previous word in \fBbash\fP:
.sp 1
.RS
.nf
.B
yank\-last\-arg (M\-.\^, M\-_\^)
Insert the last argument to the previous command (the last word of
-the previous history entry). With an argument,
-behave exactly like \fByank\-nth\-arg\fP.
+the previous history entry).
+With a numeric argument, 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.
+list, inserting the last word (or the word specified by the argument to
+the first call) of each line in turn.
+Any numeric argument supplied to these successive calls determines
+the direction to move through the history. A negative argument switches
+the direction through the history (back or forward).
The history expansion facilities are used to extract the last argument,
as if the "!$" history expansion had been specified.
.TP
This command is intended to be bound to \fBTAB\fP, but is unbound
by default.
.TP
+.B menu\-complete\-backward
+Identical to \fBmenu\-complete\fP, but moves backward through the list
+of possible completions, as if \fBmenu\-complete\fP had been given a
+negative argument. This command is unbound by default.
+.TP
.B delete\-char\-or\-list
Deletes the character under the cursor if not at the beginning or
end of the line (like \fBdelete\-char\fP).
A character is read and point is moved to the previous occurrence of that
character. A negative count searches for subsequent occurrences.
.TP
+.B skip\-csi\-sequence
+Read enough characters to consume a multi-key sequence such as those
+defined for keys like Home and End. Such sequences begin with a
+Control Sequence Indicator (CSI), usually ESC\-[. If this sequence is
+bound to "\e[", keys producing such sequences will have no effect
+unless explicitly bound to a readline command, instead of inserting
+stray characters into the editing buffer. This is unbound by default,
+but usually bound to ESC\-[.
+.TP
.B insert\-comment (M\-#)
Without a numeric argument, the value of the readline
.B comment\-begin
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 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
below), the programmable completion facilities are invoked.
.PP
First, the command name is identified.
+If the command word is the empty string (completion attempted at the
+beginning of an empty line), any compspec defined with
+the \fB\-E\fP option to \fBcomplete\fP is used.
If a compspec has been defined for that command, the
compspec is used to generate the list of possible completions for the word.
If the command word is a full pathname, a compspec for the full
pathname is searched for first.
If no compspec is found for the full pathname, an attempt is made to
find a compspec for the portion following the final slash.
+If those searches do not result in a compspec, any compspec defined with
+the \fB\-D\fP option to \fBcomplete\fP is used as the default.
.PP
Once a compspec has been found, it is used to generate the list of
matching words.
.B FIGNORE
is used to filter the matches.
.PP
-Any completions specified by a filename expansion pattern to the
+Any completions specified by a pathname expansion pattern to the
\fB\-G\fP option are generated next.
The words generated by the pattern need not match the word
being completed.
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.
+.PP
+There is some support for dynamically modifying completions. This is
+most useful when used in combination with a default completion specified
+with \fBcomplete -D\fP.
+It's possible for shell functions executed as completion
+handlers to indicate that completion should be retried by returning an
+exit status of 124. If a shell function returns 124, and changes
+the compspec associated with the command on which completion is being
+attempted (supplied as the first argument when the function is executed),
+programmable completion restarts from the beginning, with an
+attempt to find a new compspec for that command. This allows a set of
+completions to be built dynamically as completion is attempted, rather than
+being loaded all at once.
+.PP
+For instance, assuming that there is a library of compspecs, each kept in a
+file corresponding to the name of the command, the following default
+completion function would load completions dynamically:
+.PP
+\f(CW_completion_loader()
+.br
+{
+.br
+ . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124
+.br
+}
+.br
+complete -D -F _completion_loader
+.br
+\fP
.SH HISTORY
When the
.B \-o history
builtin is enabled, the shell provides access to the
\fIcommand history\fP,
the list of commands previously typed.
-The value of the \fBHISTSIZE\fP variable is used as the
+The value of the
+.SM
+.B HISTSIZE
+variable is used as the
number of commands to save in a history list.
The text of the last
.SM
not saved.
If the
.SM
-.HISTTIMEFORMAT
+.B 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.
.B histverify
shell option is enabled (see the description of the
.B shopt
-builtin), and
+builtin below), and
.B readline
is being used, history substitutions are not immediately passed to
the shell parser.
.PP
An event designator is a reference to a command line entry in the
history list.
+Unless the reference is absolute, events are relative to the current
+position in the history list.
.PP
.PD 0
.TP
.IR n .
.TP
.B !\-\fIn\fR
-Refer to the current command line minus
+Refer to the current command minus
.IR n .
.TP
.B !!
Refer to the previous command. This is a synonym for `!\-1'.
.TP
.B !\fIstring\fR
-Refer to the most recent command starting with
+Refer to the most recent command preceding the current position in the
+history list starting with
.IR string .
.TP
.B !?\fIstring\fR\fB[?]\fR
-Refer to the most recent command containing
+Refer to the most recent command preceding the current postition in the
+history list containing
.IR string .
The trailing \fB?\fP may be omitted if
.I string
is followed immediately by a newline.
.TP
.B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u
-Quick substitution. Repeat the last command, replacing
+Quick substitution. Repeat the previous command, replacing
.I string1
with
.IR string2 .
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.
+The \fB:\fP, \fBtrue\fP, \fBfalse\fP, and \fBtest\fP builtins
+do not accept options and do not treat \fB\-\-\fP specially.
+The \fBexit\fP, \fBlogout\fP, \fBbreak\fP, \fBcontinue\fP, \fBlet\fP,
+and \fBshift\fP builtins accept and process arguments beginning with
+\fB\-\fP without requiring \fB\-\-\fP.
+Other builtins that accept arguments but are not specified as accepting
+options interpret arguments beginning with \fB\-\fP as invalid options and
+require \fB\-\-\fP to prevent this interpretation.
.sp .5
.PD 0
.TP
Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is
entered.
When \fIshell\-command\fP is executed, the shell sets the
+.SM
.B READLINE_LINE
variable to the contents of the \fBreadline\fP line buffer and the
+.SM
.B READLINE_POINT
variable to the current location of the insertion point.
If the executed command changes the value of
+.SM
.B READLINE_LINE
or
+.SM
.BR READLINE_POINT ,
those new values will be reflected in the editing state.
.PD
.TP
\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.
+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
call or \fIexpr\fP does not correspond to a valid position in the
call stack.
.TP
-\fBcd\fP [\fB\-L|-P\fP] [\fIdir\fP]
+\fBcd\fP [\fB\-L\fP|[\fB\-P\fP [\fB\-e\fP]]] [\fIdir\fP]
Change the current directory to \fIdir\fP. The variable
.SM
.B HOME
.B set
builtin command); the
.B \-L
-option forces symbolic links to be followed. An argument of
+option forces symbolic links to be followed.
+If the
+.B \-e
+option is supplied with
+.BR \-P ,
+and the current working directory cannot be successfully determined
+after a successful directory change, \fBcd\fP will return an unsuccessful
+status.
+An argument of
.B \-
is equivalent to
.SM
.BR $OLDPWD .
-If a non-empty directory name from \fBCDPATH\fP is used, or if
+If a non-empty directory name from
+.SM
+.B CDPATH
+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.
option is given, the search for
.I command
is performed using a default value for
+.SM
.B PATH
that is guaranteed to find all of the standard utilities.
If either the
The return value is true unless an invalid option is supplied, or no
matches were generated.
.TP
-\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-E\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP]
+\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-DE\fP] [\fB\-A\fP \fIaction\fP] [\fB\-G\fP \fIglobpat\fP] [\fB\-W\fP \fIwordlist\fP] [\fB\-F\fP \fIfunction\fP] [\fB\-C\fP \fIcommand\fP]
.br
[\fB\-X\fP \fIfilterpat\fP] [\fB\-P\fP \fIprefix\fP] [\fB\-S\fP \fIsuffix\fP] \fIname\fP [\fIname ...\fP]
.PD 0
.TP
-\fBcomplete\fP \fB\-pr\fP [\fB\-E\fP] [\fIname\fP ...]
+\fBcomplete\fP \fB\-pr\fP [\fB\-DE\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\-D\fP option indicates that the remaining options and actions should
+apply to the ``default'' command completion; that is, completion attempted
+on a command for which no completion has previously been defined.
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.
Names of all shell variables. May also be specified as \fB\-v\fP.
.RE
.TP 8
-\fB\-G\fP \fIglobpat\fP
-The filename expansion pattern \fIglobpat\fP is expanded to generate
-the possible completions.
-.TP 8
-\fB\-W\fP \fIwordlist\fP
-The \fIwordlist\fP is split using the characters in the
-.SM
-.B IFS
-special variable as delimiters, and each resultant word is expanded.
-The possible completions are the members of the resultant list which
-match the word being completed.
-.TP 8
\fB\-C\fP \fIcommand\fP
\fIcommand\fP is executed in a subshell environment, and its output is
used as the possible completions.
.B COMPREPLY
array variable.
.TP 8
-\fB\-X\fP \fIfilterpat\fP
-\fIfilterpat\fP is a pattern as used for filename expansion.
-It is applied to the list of possible completions generated by the
-preceding options and arguments, and each completion matching
-\fIfilterpat\fP is removed from the list.
-A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this
-case, any completion not matching \fIfilterpat\fP is removed.
+\fB\-G\fP \fIglobpat\fP
+The pathname expansion pattern \fIglobpat\fP is expanded to generate
+the possible completions.
.TP 8
\fB\-P\fP \fIprefix\fP
\fIprefix\fP is added at the beginning of each possible completion
\fB\-S\fP \fIsuffix\fP
\fIsuffix\fP is appended to each possible completion
after all other options have been applied.
+.TP 8
+\fB\-W\fP \fIwordlist\fP
+The \fIwordlist\fP is split using the characters in the
+.SM
+.B IFS
+special variable as delimiters, and each resultant word is expanded.
+The possible completions are the members of the resultant list which
+match the word being completed.
+.TP 8
+\fB\-X\fP \fIfilterpat\fP
+\fIfilterpat\fP is a pattern as used for pathname expansion.
+It is applied to the list of possible completions generated by the
+preceding options and arguments, and each completion matching
+\fIfilterpat\fP is removed from the list.
+A leading \fB!\fP in \fIfilterpat\fP negates the pattern; in this
+case, any completion not matching \fIfilterpat\fP is removed.
.PD
.PP
The return value is true unless an invalid option is supplied, an option
an error occurs adding a completion specification.
.RE
.TP
-\fBcompopt\fP [\fB\-o\fP \fIoption\fP] [\fB+o\fP \fIoption\fP] [\fIname\fP]
+\fBcompopt\fP [\fB\-o\fP \fIoption\fP] [\fB\-DE\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.
+currently-executing 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 \fB\-D\fP option indicates that the remaining options should
+apply to the ``default'' command completion; that is, completion attempted
+on a command for which no completion has previously been defined.
+The \fB\-E\fP option indicates that the remaining options should
+apply to ``empty'' command completion; that is, completion attempted on a
+blank line.
+.sp 1
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.
(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] ...]
+\fBdeclare\fP [\fB\-aAfFgilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
.PD 0
.TP
-\fBtypeset\fP [\fB\-aAfFilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
+\fBtypeset\fP [\fB\-aAfFgilrtux\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.
.B \-F
option implies
.BR \-f .
+The
+.B \-g
+option forces variables to be created or modified at the global scope,
+even when \fBdeclare\fP is executed in a shell function.
+It is ignored in all other cases.
The following options can
be used to restrict output to variables with the specified attribute or
to give variables attributes:
.B \-i
The variable is treated as an integer; arithmetic evaluation (see
.SM
-.B "ARITHMETIC EVALUATION" ") "
-is performed when the variable is assigned a value.
+.B "ARITHMETIC EVALUATION"
+above) is performed when the variable is assigned a value.
.TP
.B \-l
When the variable is assigned a value, all upper-case characters are
Using `+' instead of `\-'
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
+may not be used to destroy an array variable and \fB+r\fP will not
remove the readonly attribute.
-When used in a function,
-makes each
-\fIname\fP local, as with the
+When used in a function, makes each
+\fIname\fP local, as with the
.B local
-command.
+command,
+unless the \fB\-g\fP option is supplied,
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,
or an attempt is made to display a non-existent function with \fB\-f\fP.
.RE
.TP
-.B dirs [+\fIn\fP] [\-\fIn\fP] [\fB\-cplv\fP]
+.B dirs [+\fIn\fP] [\-\fIn\fP] [\fB\-clpv\fP]
Without options, displays the list of currently remembered directories.
The default display is on a single line with directory names separated
by spaces.
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,
+is not present, and neither \fB\-a\fP 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
suppress further output
.TP
.B \ee
+.TP
+.B \eE
an escape character
.TP
.B \ef
.B \ex\fIHH\fP
the eight-bit character whose value is the hexadecimal value \fIHH\fP
(one or two hex digits)
+.TP
+.B \eu\fIHHHH\fP
+the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
+\fIHHHH\fP (one to four hex digits)
+.TP
+.B \eU\fIHHHHHHHH\fP
+the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
+\fIHHHHHHHH\fP (one to eight hex digits)
.PD
.RE
.TP
.sp 1
When the end of options is encountered, \fBgetopts\fP exits with a
return value greater than zero.
-\fBOPTIND\fP is set to the index of the first non-option argument,
-and \fBname\fP is set to ?.
+.SM
+.B OPTIND
+is set to the index of the first non-option argument,
+and \fIname\fP is set to ?.
.sp 1
.B getopts
normally parses the positional parameters, but if more arguments are
error occurs.
.TP
\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
+Each time \fBhash\fP is invoked,
+the full pathname of the command
+.I name
+is determined by searching
the directories in
.B $PATH
-and remembered.
+and remembered. Any previously-remembered pathname is discarded.
If the
.B \-p
option is supplied, no path search is performed, and
.B \-d
Display a short description of each \fIpattern\fP
.TP
-.B \ -m
+.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
+.PP
The return status is 0 unless no command matches
.IR pattern .
+.RE
.TP
\fBhistory [\fIn\fP]
.PD 0
lists only the last
.I n
lines.
-If the shell variable \fBHISTTIMEFORMAT\fP is set and not null,
+If the shell variable
+.SM
+.B HISTTIMEFORMAT
+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
are added.
.PD
.PP
-If the \fBHISTTIMEFORMAT\fP is set, the time stamp information
+If the
+.SM
+.B HISTTIMEFORMAT
+variable 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
List process IDs
in addition to the normal information.
.TP
-.B \-p
-List only the process ID of the job's process group
-leader.
-.TP
.B \-n
Display information only about jobs that have changed status since
the user was last notified of their status.
.TP
+.B \-p
+List only the process ID of the job's process group
+leader.
+.TP
.B \-r
Restrict output to running jobs.
.TP
.I arg
is an arithmetic expression to be evaluated (see
.SM
-.BR "ARITHMETIC EVALUATION" ).
+.B "ARITHMETIC EVALUATION"
+above).
If the last
.I arg
evaluates to 0,
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
+.PD 0
+.TP
+\fBreadarray\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]
+.PD
+Read lines from the standard input into the indexed 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.
+The variable
+.SM
+.B MAPFILE
+is the default \fIarray\fP.
Options, if supplied, have the following meanings:
.RS
.PD 0
Discard the first \fIcount\fP lines read.
.TP
.B \-t
-Remove a trailing line from each line read.
+Remove a trailing newline from each line read.
.TP
.B \-u
Read lines from file descriptor \fIfd\fP instead of the standard input.
is specified without
.BR \-c ,
the default quantum is 5000.
+When \fIcallback\fP is evaluated, it is supplied the index of the next
+array element to be assigned and the line to be assigned to that element
+as additional arguments.
+\fIcallback\fP is evaluated after the line is read but before the
+array element is assigned.
.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.
+argument is supplied, \fIarray\fP is invalid or unassignable, or if
+\fIarray\fP is not an indexed array.
.RE
.TP
\fBpopd\fP [\-\fBn\fP] [+\fIn\fP] [\-\fIn\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 \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 a character string which contains three types of objects:
plain characters, which are simply copied to standard output, character
escape sequences, which are converted and copied to the standard output, and
format specifications, each of which causes printing of the next successive
\fIargument\fP.
-In addition to the standard \fIprintf\fP(1) formats, \fB%b\fP causes
+In addition to the standard \fIprintf\fP(1) format specifications,
+\fBprintf\fP interprets the following extensions:
+.RS
+.PD 0
+.TP
+.B %b
+causes
\fBprintf\fP to expand backslash escape sequences in 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
+beginning with \fB\e0\fP may contain up to four digits).
+.TP
+.B %q
+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
+.TP
+.B %(\fIdatefmt\fP)T
+causes \fBprintf\fP to output the date-time string resulting from using
+\fIdatefmt\fP as a format string for \fIstrftime\fP(3). The corresponding
+\fIargument\fP is an integer representing the number of seconds since the
+epoch. Two special argument values may be used: -1 represents the current
+time, and -2 represents the time the shell was invoked.
+.PD
+.PP
+Arguments to non-string format specifiers are treated as C constants,
+except that a leading plus or minus sign is allowed, and if the leading
+character is a single or double quote, the value is the ASCII value of
+the following character.
+.PP
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.
+appropriate, had been supplied.
+The return value is zero on success, non-zero on failure.
+.RE
.TP
\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP]
.PD 0
reading the name of the current directory or an
invalid option is supplied.
.TP
-\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 ...]
+\fBread\fP [\fB\-ers\fP] [\fB\-a\fP \fIaname\fP] [\fB\-d\fP \fIdelim\fP] [\fB\-i\fP \fItext\fP] [\fB\-n\fP \fInchars\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
.TP
.B \-n \fInchars\fP
\fBread\fP returns after reading \fInchars\fP characters rather than
-waiting for a complete line of input.
+waiting for a complete line of input, but honor a delimiter if fewer
+than \fInchars\fP characters are read before the delimiter.
+.TP
+.B \-N \fInchars\fP
+\fBread\fP returns after reading exactly \fInchars\fP characters rather
+than waiting for a complete line of input, unless EOF is encountered or
+\fBread\fP times out.
+Delimiter characters encountered in the input are
+not treated specially and do not cause \fBread\fP to return until
+\fInchars\fP characters are read.
.TP
.B \-p \fIprompt\fP
Display \fIprompt\fP on standard error, without a
invalid file descriptor is supplied as the argument to \fB\-u\fP.
.RE
.TP
-\fBreadonly\fP [\fB\-aApf\fP] [\fIname\fP[=\fIword\fP] ...]
+\fBreadonly\fP [\fB\-aAf\fP] [\fB\-p\fP] [\fIname\fP[=\fIword\fP] ...]
.PD
The given
\fInames\fP are marked readonly; the values of these
option restricts the variables to indexed arrays; the
.B \-A
option restricts the variables to associative arrays.
+If both options are supplied,
+.B \-A
+takes precedence.
If no
.I name
arguments are given, or if the
.B \-p
option is supplied, a list of all readonly names is printed.
+The other options may be used to restrict the output to a subset of
+the set of readonly names.
The
.B \-p
option causes output to be displayed in a format that
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 ...]
+\fBset\fP [\fB\-\-abefhkmnptuvxBCEHPT\fP] [\fB\-o\fP \fIoption\-name\fP] [\fIarg\fP ...]
.PD 0
.TP
-\fBset\fP [\fB+abefhkmnptuvxBCEHPT\fP] [\fB+o\fP \fIoption\fP] [\fIarg\fP ...]
+\fBset\fP [\fB+abefhkmnptuvxBCEHPT\fP] [\fB+o\fP \fIoption\-name\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
effective only when job control is enabled.
.TP 8
.B \-e
-Exit immediately if a \fIsimple command\fP (see
+Exit immediately if a \fIpipeline\fP (which may consist of a single
+\fIsimple command\fP), a \fIsubshell\fP command enclosed in parentheses,
+or one of the commands executed as part of a command list enclosed
+by braces (see
.SM
.B SHELL GRAMMAR
above) exits with a non-zero status.
or
.B until
keyword,
-part of the test in an
+part of the test following the
.B if
-statement, part of a command executed in a
+or
+.B elif
+reserved words, part of any command executed in a
.B &&
or
-.B \(bv\(bv
-list,
+.B ||
+list except the command following the final \fB&&\fP or \fB||\fP,
any command in a pipeline but the last,
or if the command's return value is
-being inverted via
+being inverted with
.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.
+This option applies to the shell environment and each subshell environment
+separately (see
+.SM
+.B "COMMAND EXECUTION ENVIRONMENT"
+above), and may cause
+subshells to exit before executing all the commands in the subshell.
.TP 8
.B \-f
Disable pathname expansion.
option.
This also affects the editing interface used for \fBread \-e\fP.
.TP 8
+.B errexit
+Same as
+.BR \-e .
+.TP 8
.B errtrace
Same as
.BR \-E .
Same as
.BR \-T .
.TP 8
-.B errexit
-Same as
-.BR \-e .
-.TP 8
.B hashall
Same as
.BR \-h .
environment, and the
.SM
.BR SHELLOPTS ,
+.SM
+.BR BASHOPTS ,
+.SM
.BR CDPATH ,
and
+.SM
.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
Exit after reading and executing one command.
.TP 8
.B \-u
-Treat unset variables as an error when performing
+Treat unset variables and parameters other than the special
+parameters "@" and "*" as an error when performing
parameter expansion. If expansion is attempted on an
-unset variable, the shell prints an error message, and,
+unset variable or parameter, the shell prints an error message, and,
if not interactive, exits with a non-zero status.
.TP 8
.B \-v
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
+intervening command (see
+.SM
+.B "JOB CONTROL"
+above). The shell always
postpones exiting if any jobs are stopped.
.TP 8
.B checkwinsize
If set,
.B bash
changes its behavior to that of version 3.1 with respect to quoted
-arguments to the conditional command's =~ operator.
+arguments to the \fB[[\fP conditional command's \fB=~\fP operator.
+.TP 8
+.B compat32
+If set,
+.B bash
+changes its behavior to that of version 3.2 with respect to locale-specific
+string comparison when using the \fB[[\fP
+conditional command's \fB<\fP and \fB>\fP operators.
+Bash versions prior to bash-4.1 use ASCII collation and
+.IR strcmp (3);
+bash-4.1 and later
+use the current locale's collation sequence and
+.IR strcoll (3).
+.TP 8
+.B compat40
+If set,
+.B bash
+changes its behavior to that of version 4.0 with respect to locale-specific
+string comparison when using the \fB[[\fP
+conditional command's \fB<\fP and \fB>\fP operators (see previous item)
+and the effect of interrupting a command list.
+.TP 8
+.B compat41
+If set,
+.BR bash ,
+when in posix mode, treats a single quote in a double-quoted
+parameter expansion as a special character. The single quotes must match
+(an even number) and the characters between the single quotes are considered
+quoted. This is the behavior of posix mode through version 4.1.
+The default bash behavior remains as in previous versions.
.TP 8
.B dirspell
If set,
\fBreturn\fP is simulated.
.TP
.B 4.
-\fBBASH_ARGC\fP and \fBBASH_ARGV\fP are updated as described in their
-descriptions above.
+.SM
+.B BASH_ARGC
+and
+.SM
+.B BASH_ARGV
+are updated as described in their descriptions above.
.TP
.B 5.
Function tracing is enabled: command substitution, shell functions, and
.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.
+\fBERR\fP trap.
.RE
.TP 8
.B extglob
result in an expansion error.
.TP 8
.B force_fignore
-If set, the suffixes specified by the \fBFIGNORE\fP shell variable
+If set, the suffixes specified by the
+.SM
+.B FIGNORE
+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.
+above for a description of
+.SM
+.BR FIGNORE .
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 set, the pattern \fB**\fP used in a pathname expansion context will
+match all 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 histappend
If set, the history list is appended to the file named by the value
of the
+.SM
.B HISTFILE
variable when the shell exits, rather than overwriting the file.
.TP 8
.B COMMENTS
above). This option is enabled by default.
.TP 8
+.B lastpipe
+If set, and job control is not active, the shell runs the last command of
+a pipeline not executed in the background in the current shell environment.
+.TP 8
.B lithist
If set, and the
.B cmdhist
.B readline
is being used,
.B bash
-will not attempt to search the \fBPATH\fP for possible completions when
+will not attempt to search the
+.SM
+.B PATH
+for possible completions when
completion is attempted on an empty line.
.TP 8
.B nocaseglob
If set, the \fBecho\fP builtin expands backslash-escape sequences
by default.
.RE
+.PD
.TP
\fBsuspend\fP [\fB\-f\fP]
Suspend the execution of this shell until it receives a
Expressions may be combined using the following operators, listed
in decreasing order of precedence.
The evaluation depends on the number of arguments; see below.
+Operator precedence is used when there are five or more arguments.
.RS
.PD 0
.TP
is false.
.TP
3 arguments
+The following conditions are applied in the order listed.
If the second argument is one of the binary conditional operators listed above
under
.SM
5 or more arguments
The expression is parsed and evaluated according to precedence
using the rules listed above.
+.if t .sp 0.5
+.if n .sp 1
+.LP
+When used with \fBtest\fP or \fB[\fP, the \fB<\fP and \fB>\fP operators
+sort lexicographically using ASCII ordering.
.RE
.PD
.TP
.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.
+Signal names are case insensitive and the
+.SM
+.B SIG
+prefix is optional.
+.if t .sp 0.5
+.if n .sp 1
If a
.I sigspec
is
.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.
+.if t .sp 0.5
+.if n .sp 1
+If a
+.I sigspec
+is
+.SM
.BR ERR ,
the command
.I arg
statement, part of a command executed in a
.B &&
or
-.B \(bv\(bv
+.B ||
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.
+.if t .sp 0.5
+.if n .sp 1
Signals ignored upon entry to the shell cannot be trapped or reset.
Trapped signals that are not being ignored are reset to their original
-values in a child process when it is created.
+values in a subshell or subshell environment when one is created.
The return status is false if any
.I sigspec
is invalid; otherwise
The maximum size that may be locked into memory
.TP
.B \-m
-The maximum resident set size
+The maximum resident set size (many systems do not honor this limit)
.TP
.B \-n
The maximum number of open file descriptors (most systems do not
The maximum number of processes available to a single user
.TP
.B \-v
-The maximum amount of virtual memory available to the shell
+The maximum amount of virtual memory available to the shell and, on
+some systems, to its children
.TP
.B \-x
The maximum number of file locks
passed to subsequent commands.
If any of
.SM
+.BR COMP_WORDBREAKS ,
+.SM
.BR RANDOM ,
.SM
.BR SECONDS ,
changing directories with \fBcd\fP
.IP \(bu
setting or unsetting the values of
+.SM
.BR SHELL ,
+.SM
.BR PATH ,
+.SM
.BR ENV ,
or
+.SM
.B BASH_ENV
.IP \(bu
specifying command names containing
.B .
builtin command
.IP \(bu
-Specifying a filename containing a slash as an argument to the
+specifying a filename containing a slash as an argument to the
.B \-p
option to the
.B hash
.IP \(bu
importing function definitions from the shell environment at startup
.IP \(bu
-parsing the value of \fBSHELLOPTS\fP from the shell environment at startup
+parsing the value of
+.SM
+.B SHELLOPTS
+from the shell environment at startup
.IP \(bu
redirecting output using the >, >|, <>, >&, &>, and >> redirection operators
.IP \(bu
.B enable
builtin command
.IP \(bu
-Using the \fBenable\fP builtin command to enable disabled shell builtins
+using the \fBenable\fP builtin command to enable disabled shell builtins
.IP \(bu
specifying the
.B \-p
.PP
Chet Ramey, Case Western Reserve University
.br
-chet@po.cwru.edu
+chet.ramey@case.edu
.SH BUG REPORTS
If you find a bug in
.B bash,
version of
.BR bash .
The latest version is always available from
-\fIftp://ftp.gnu.org/pub/bash/\fP.
+\fIftp://ftp.gnu.org/pub/gnu/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@po.cwru.edu .
+.IR chet.ramey@case.edu .
.SH BUGS
.PP
It's too big and too slow.
projects / platform / upstream / bash.git / blobdiff