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diff --git a/doc/bash.1~ b/doc/bash.1~ deleted file mode 100644 index 45dc80fd..00000000 --- a/doc/bash.1~ +++ /dev/null @@ -1,10345 +0,0 @@ -.\" -.\" MAN PAGE COMMENTS to -.\" -.\" Chet Ramey -.\" Case Western Reserve University -.\" chet.ramey@case.edu -.\" -.\" Last Change: Tue Jul 1 15:51:28 PDT 2014 -.\" -.\" bash_builtins, strip all but Built-Ins section -.if \n(zZ=1 .ig zZ -.if \n(zY=1 .ig zY -.TH BASH 1 "2014 July 1" "GNU Bash 4.3" -.\" -.\" There's some problem with having a `@' -.\" in a tagged paragraph with the BSD man macros. -.\" It has to do with `@' appearing in the }1 macro. -.\" This is a problem on 4.3 BSD and Ultrix, but Sun -.\" appears to have fixed it. -.\" If you're seeing the characters -.\" `@u-3p' appearing before the lines reading -.\" `possible-hostname-completions -.\" and `complete-hostname' down in READLINE, -.\" then uncomment this redefinition. -.\" -.de }1 -.ds ]X \&\\*(]B\\ -.nr )E 0 -.if !"\\$1"" .nr )I \\$1n -.}f -.ll \\n(LLu -.in \\n()Ru+\\n(INu+\\n()Iu -.ti \\n(INu -.ie !\\n()Iu+\\n()Ru-\w\\*(]Xu-3p \{\\*(]X -.br\} -.el \\*(]X\h|\\n()Iu+\\n()Ru\c -.}f -.. -.\" -.\" File Name macro. This used to be `.PN', for Path Name, -.\" but Sun doesn't seem to like that very much. -.\" -.de FN -\fI\|\\$1\|\fP -.. -.SH NAME -bash \- GNU Bourne-Again SHell -.SH SYNOPSIS -.B bash -[options] -[command_string | file] -.SH COPYRIGHT -.if n Bash is Copyright (C) 1989-2013 by the Free Software Foundation, Inc. -.if t Bash is Copyright \(co 1989-2013 by the Free Software Foundation, Inc. -.SH DESCRIPTION -.B Bash -is an \fBsh\fR-compatible command language interpreter that -executes commands read from the standard input or from a file. -.B Bash -also incorporates useful features from the \fIKorn\fP and \fIC\fP -shells (\fBksh\fP and \fBcsh\fP). -.PP -.B Bash -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 -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 -.TP 10 -.B \-c -If the -.B \-c -option is present, then commands are read from the first non-option argument -.IR command_string . -If there are arguments after the -.IR command_string , -they are assigned to the positional parameters, starting with -.BR $0 . -.TP -.B \-i -If the -.B \-i -option is present, the shell is -.IR interactive . -.TP -.B \-l -Make -.B bash -act as if it had been invoked as a login shell (see -.SM -.B INVOCATION -below). -.TP -.B \-r -If the -.B \-r -option is present, the shell becomes -.I restricted -(see -.SM -.B "RESTRICTED SHELL" -below). -.TP -.B \-s -If the -.B \-s -option is present, or if no arguments remain after option -processing, then commands are read from the standard input. -This option allows the positional parameters to be set -when invoking an interactive shell. -.TP -.B \-D -A list of all double-quoted strings preceded by \fB$\fP -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 \-\- -signals the end of options and disables further option processing. -Any arguments after the -.B \-\- -are treated as filenames and arguments. An argument of -.B \- -is equivalent to \fB\-\-\fP. -.PD -.PP -.B Bash -also interprets a number of multi-character options. -These options must appear on the command line before the -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). -.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. -.TP -.B \-\-dump\-strings -Equivalent to \fB\-D\fP. -.TP -.B \-\-help -Display a usage message on standard output and exit successfully. -.TP -\fB\-\-init\-file\fP \fIfile\fP -.PD 0 -.TP -\fB\-\-rcfile\fP \fIfile\fP -.PD -Execute commands from -.I file -instead of the standard personal initialization file -.I ~/.bashrc -if the shell is interactive (see -.SM -.B INVOCATION -below). -.TP -.B \-\-login -Equivalent to \fB\-l\fP. -.TP -.B \-\-noediting -Do not use the GNU -.B readline -library to read command lines when the shell is interactive. -.TP -.B \-\-noprofile -Do not read either the system-wide startup file -.FN /etc/profile -or any of the personal initialization files -.IR ~/.bash_profile , -.IR ~/.bash_login , -or -.IR ~/.profile . -By default, -.B bash -reads these files when it is invoked as a login shell (see -.SM -.B INVOCATION -below). -.TP -.B \-\-norc -Do not read and execute the personal initialization file -.I ~/.bashrc -if the shell is interactive. -This option is on by default if the shell is invoked as -.BR sh . -.TP -.B \-\-posix -Change the behavior of \fBbash\fP where the default operation differs -from the POSIX standard to match the standard (\fIposix mode\fP). -See -.SM -.B "SEE ALSO" -below for a reference to a document that details how posix mode affects -bash's behavior. -.TP -.B \-\-restricted -The shell becomes restricted (see -.SM -.B "RESTRICTED SHELL" -below). -.TP -.B \-\-verbose -Equivalent to \fB\-v\fP. -.TP -.B \-\-version -Show version information for this instance of -.B bash -on the standard output and exit successfully. -.PD -.SH ARGUMENTS -If arguments remain after option processing, and neither the -.B \-c -nor the -.B \-s -option has been supplied, the first argument is assumed to -be the name of a file containing shell commands. -If -.B bash -is invoked in this fashion, -.B $0 -is set to the name of the file, and the positional parameters -are set to the remaining arguments. -.B Bash -reads and executes commands from this file, then exits. -\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 \- , -or one started with the -.B \-\-login -option. -.PP -An \fIinteractive\fP shell is one started without non-option arguments -and without the -.B \-c -option -whose standard input and error are -both connected to terminals (as determined by -.IR isatty (3)), -or one started with the -.B \-i -option. -.SM -.B PS1 -is set and -.B $\- -includes -.B i -if -.B bash -is interactive, -allowing a shell script or a startup file to test this state. -.PP -The following paragraphs describe how -.B bash -executes its startup files. -If any of the files exist but cannot be read, -.B bash -reports an error. -Tildes are expanded in filenames as described below under -.B "Tilde Expansion" -in the -.SM -.B EXPANSION -section. -.PP -When -.B bash -is invoked as an interactive login shell, or as a non-interactive shell -with the \fB\-\-login\fP option, it first reads and -executes commands from the file \fI/etc/profile\fP, if that -file exists. -After reading that file, it looks for \fI~/.bash_profile\fP, -\fI~/.bash_login\fP, and \fI~/.profile\fP, in that order, and reads -and executes commands from the first one that exists and is readable. -The -.B \-\-noprofile -option may be used when the shell is started to inhibit this behavior. -.PP -When a login shell exits, -.B bash -reads and executes commands from the file \fI~/.bash_logout\fP, if it -exists. -.PP -When an interactive shell that is not a login shell is started, -.B bash -reads and executes commands from \fI~/.bashrc\fP, if that file exists. -This may be inhibited by using the -.B \-\-norc -option. -The \fB\-\-rcfile\fP \fIfile\fP option will force -.B bash -to read and execute commands from \fIfile\fP instead of \fI~/.bashrc\fP. -.PP -When -.B bash -is started non-interactively, to run a shell script, for example, it -looks for the variable -.SM -.B BASH_ENV -in the environment, expands its value if it appears there, and uses the -expanded value as the name of a file to read and execute. -.B Bash -behaves as if the following command were executed: -.sp .5 -.RS -.if t \f(CWif [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi\fP -.if n if [ \-n "$BASH_ENV" ]; then . "$BASH_ENV"; fi -.RE -.sp .5 -but the value of the -.SM -.B PATH -variable is not used to search for the filename. -.PP -If -.B bash -is invoked with the name -.BR sh , -it tries to mimic the startup behavior of historical versions of -.B sh -as closely as possible, -while conforming to the POSIX standard as well. -When invoked as an interactive login shell, or a non-interactive -shell with the \fB\-\-login\fP option, it first attempts to -read and execute commands from -.I /etc/profile -and -.IR ~/.profile , -in that order. -The -.B \-\-noprofile -option may be used to inhibit this behavior. -When invoked as an interactive shell with the name -.BR sh , -.B bash -looks for the variable -.SM -.BR ENV , -expands its value if it is defined, and uses the -expanded value as the name of a file to read and execute. -Since a shell invoked as -.B sh -does not attempt to read and execute commands from any other startup -files, the -.B \-\-rcfile -option has no effect. -A non-interactive shell invoked with the name -.B sh -does not attempt to read any other startup files. -When invoked as -.BR sh , -.B bash -enters -.I posix -mode after the startup files are read. -.PP -When -.B bash -is started in -.I posix -mode, as with the -.B \-\-posix -command line option, it follows the POSIX standard for startup files. -In this mode, interactive shells expand the -.SM -.B ENV -variable and commands are read and executed from the file -whose name is the expanded value. -No other startup files are read. -.PP -.B Bash -attempts to determine when it is being run with its standard input -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 -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 -.B \-\-norc -option may be used to inhibit this behavior, and the -.B \-\-rcfile -option may be used to force another file to be read, but neither -\fIrshd\fP nor \fIsshd\fP generally invoke the shell with those options -or allow them to be specified. -.PP -If the shell is started with the effective user (group) id not equal to the -real user (group) id, and the \fB\-p\fP option is not supplied, no startup -files are read, shell functions are not inherited from the environment, the -.SM -.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. -.SH DEFINITIONS -.PP -The following definitions are used throughout the rest of this -document. -.PD 0 -.TP -.B blank -A space or tab. -.TP -.B word -A sequence of characters considered as a single unit by the shell. -Also known as a -.BR token . -.TP -.B name -A -.I word -consisting only of alphanumeric characters and underscores, and -beginning with an alphabetic character or an underscore. Also -referred to as an -.BR identifier . -.TP -.B metacharacter -A character that, when unquoted, separates words. One of the following: -.br -.RS -.PP -.if t \fB| & ; ( ) < > space tab\fP -.if n \fB| & ; ( ) < > space tab\fP -.RE -.PP -.TP -.B control operator -A \fItoken\fP that performs a control function. It is one of the following -symbols: -.RS -.PP -.if t \fB|| & && ; ;; ( ) | |& <newline>\fP -.if n \fB|| & && ; ;; ( ) | |& <newline>\fP -.RE -.PD -.SH "RESERVED WORDS" -\fIReserved words\fP are words that have a special meaning to the shell. -The following words are recognized as reserved when unquoted and either -the first word of a simple command (see -.SM -.B SHELL GRAMMAR -below) or the third word of a -.B case -or -.B for -command: -.if t .RS -.PP -.B -.if n ! case coproc do done elif else esac fi for function if in select then until while { } time [[ ]] -.if t ! case coproc do done elif else esac fi for function if in select then until while { } time [[ ]] -.if t .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, 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 -.IR n . -.SS Pipelines -.PP -A \fIpipeline\fP is a sequence of one or more commands separated by -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\(bv\fB|&\fP] \fIcommand2\fP ... ] -.RE -.PP -The standard output of -.I command -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). -If \fB|&\fP is used, \fIcommand\fP's standard error, in addition to its -standard output, 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 to the standard output 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 -negation of the exit status as described above. -The shell waits for all commands in the pipeline to -terminate before returning a value. -.PP -If the -.B time -reserved word precedes a pipeline, the elapsed as well as user and -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 -variable may be set to a format string that specifies how the timing -information should be displayed; see the description of -.SM -.B TIMEFORMAT -under -.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 -.PP -A \fIlist\fP is a sequence of one or more pipelines separated by one -of the operators -.BR ; , -.BR & , -.BR && , -or -.BR || , -and optionally terminated by one of -.BR ; , -.BR & , -or -.BR <newline> . -.PP -Of these list operators, -.B && -and -.B || -have equal precedence, followed by -.B ; -and -.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 -in a subshell. The shell does not wait for the command to -finish, and the return status is 0. Commands separated by a -.B ; -are executed sequentially; the shell waits for each -command to terminate in turn. The return status is the -exit status of the last command executed. -.PP -AND and OR lists are sequences of one of more pipelines separated by the -\fB&&\fP and \fB||\fP control operators, respectively. -AND and OR lists are executed with left associativity. -An AND list has the form -.RS -.PP -\fIcommand1\fP \fB&&\fP \fIcommand2\fP -.RE -.PP -.I command2 -is executed if, and only if, -.I command1 -returns an exit status of zero. -.PP -An OR list has the form -.RS -.PP -\fIcommand1\fP \fB||\fP \fIcommand2\fP -.PP -.RE -.PP -.I command2 -is executed if and only if -.I command1 -returns a non-zero exit status. -The return status of -AND and OR lists is the exit status of the last command -executed in the list. -.SS Compound Commands -.PP -A \fIcompound command\fP is one of the following. -In most cases a \fIlist\fP in a command's description may be separated from -the rest of the command by one or more newlines, and may be followed by a -newline in place of a semicolon. -.TP -(\fIlist\fP) -\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. -.TP -{ \fIlist\fP; } -\fIlist\fP is simply executed in the current shell environment. -\fIlist\fP must be terminated with a newline or semicolon. -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 -below under -.SM -.BR "ARITHMETIC EVALUATION" . -If the value of the expression is non-zero, the return status is 0; -otherwise the return status is 1. This is exactly equivalent to -\fBlet "\fIexpression\fP"\fR. -.TP -\fB[[\fP \fIexpression\fP \fB]]\fP -Return a status of 0 or 1 depending on the evaluation of -the conditional expression \fIexpression\fP. -Expressions are composed of the primaries described below under -.SM -.BR "CONDITIONAL EXPRESSIONS" . -Word splitting and pathname expansion are not performed on the words -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 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, -as if the \fBextglob\fP shell option were enabled. -The \fB=\fP operator is equivalent to \fB==\fP. -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 the quoted portion -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 the quoted portion -to be matched as a string. -Bracket expressions in regular expressions must be treated carefully, -since normal quoting characters lose their meanings between brackets. -If the pattern is stored in a shell variable, quoting the variable -expansion forces the entire pattern to be matched as a string. -Substrings matched by parenthesized subexpressions within the regular -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 -.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 -Expressions may be combined using the following operators, listed -in decreasing order of precedence: -.if t .sp 0.5 -.if n .sp 1 -.RS -.PD 0 -.TP -.B ( \fIexpression\fP ) -Returns the value of \fIexpression\fP. -This may be used to override the normal precedence of operators. -.TP -.B ! \fIexpression\fP -True if -.I expression -is false. -.TP -\fIexpression1\fP \fB&&\fP \fIexpression2\fP -True if both -.I expression1 -and -.I expression2 -are true. -.TP -\fIexpression1\fP \fB||\fP \fIexpression2\fP -True if either -.I expression1 -or -.I expression2 -is true. -.PD -.LP -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 -The list of words following \fBin\fP is expanded, generating a list -of items. -The variable \fIname\fP is set to each element of this list -in turn, and \fIlist\fP is executed each time. -If the \fBin\fP \fIword\fP is omitted, the \fBfor\fP command executes -\fIlist\fP once for each positional parameter that is set (see -.SM -.B PARAMETERS -below). -The return status is the exit status of the last command that executes. -If the expansion of the items following \fBin\fP results in an empty -list, no commands are executed, and the return status is 0. -.TP -\fBfor\fP (( \fIexpr1\fP ; \fIexpr2\fP ; \fIexpr3\fP )) ; \fBdo\fP \fIlist\fP ; \fBdone\fP -First, the arithmetic expression \fIexpr1\fP is evaluated according -to the rules described below under -.SM -.BR "ARITHMETIC EVALUATION" . -The arithmetic expression \fIexpr2\fP is then evaluated repeatedly -until it evaluates to zero. -Each time \fIexpr2\fP evaluates to a non-zero value, \fIlist\fP is -executed and the arithmetic expression \fIexpr3\fP is evaluated. -If any expression is omitted, it behaves as if it evaluates to 1. -The return value is the exit status of the last command in \fIlist\fP -that is executed, or false if any of the expressions is invalid. -.TP -\fBselect\fP \fIname\fP [ \fBin\fP \fIword\fP ] ; \fBdo\fP \fIlist\fP ; \fBdone\fP -The list of words following \fBin\fP is expanded, generating a list -of items. The set of expanded words is printed on the standard -error, each preceded by a number. If the \fBin\fP -\fIword\fP is omitted, the positional parameters are printed (see -.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 -the displayed words, then the value of -.I name -is set to that word. If the line is empty, the words and prompt -are displayed again. If EOF is read, the command completes. Any -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 -is executed after each selection until a -.B break -command is executed. -The exit status of -.B select -is the exit status of the last command executed in -.IR list , -or zero if no commands were executed. -.TP -\fBcase\fP \fIword\fP \fBin\fP [ [(] \fIpattern\fP [ \fB|\fP \fIpattern\fP ] \ -... ) \fIlist\fP ;; ] ... \fBesac\fP -A \fBcase\fP command first expands \fIword\fP, and tries to match -it against each \fIpattern\fP in turn, using the same matching rules -as for pathname expansion (see -.B Pathname Expansion -below). -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 -\fBif\fP \fIlist\fP; \fBthen\fP \fIlist\fP; \ -[ \fBelif\fP \fIlist\fP; \fBthen\fP \fIlist\fP; ] ... \ -[ \fBelse\fP \fIlist\fP; ] \fBfi\fP -The -.B if -.I list -is executed. If its exit status is zero, the -\fBthen\fP \fIlist\fP is executed. Otherwise, each \fBelif\fP -\fIlist\fP is executed in turn, and if its exit status is zero, -the corresponding \fBthen\fP \fIlist\fP is executed and the -command completes. Otherwise, the \fBelse\fP \fIlist\fP is -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-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP -.PD 0 -.TP -\fBuntil\fP \fIlist-1\fP; \fBdo\fP \fIlist-2\fP; \fBdone\fP -.PD -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; -.I list-2 -is executed as long as the last command in -.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 command executed in \fIlist-2\fP, or zero if -none was executed. -.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 \fBCOPROC\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 coprocess 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 file descriptors are not available in subshells. -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 -Since the coprocess is created as an asynchronous command, -the \fBcoproc\fP command always returns success. -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 -\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. -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, -with one exception: If the \fBfunction\fP reserved word is used, but the -parentheses are not supplied, the braces are required. -\fIcompound\-command\fP is executed whenever \fIname\fP is specified as the -name of a simple command. -When in \fIposix mode\fP, \fIname\fP may not be the name of one of the -POSIX \fIspecial builtins\fP. -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.) -.SH COMMENTS -In a non-interactive shell, or an interactive shell in which the -.B interactive_comments -option to the -.B shopt -builtin is enabled (see -.SM -.B "SHELL BUILTIN COMMANDS" -below), a word beginning with -.B # -causes that word and all remaining characters on that line to -be ignored. An interactive shell without the -.B interactive_comments -option enabled does not allow comments. The -.B interactive_comments -option is on by default in interactive shells. -.SH QUOTING -\fIQuoting\fP is used to remove the special meaning of certain -characters or words to the shell. Quoting can be used to -disable special treatment for special characters, to prevent -reserved words from being recognized as such, and to prevent -parameter expansion. -.PP -Each of the \fImetacharacters\fP listed above under -.SM -.B DEFINITIONS -has special meaning to the shell and must be quoted if it is to -represent itself. -.PP -When the command history expansion facilities are being used -(see -.SM -.B HISTORY EXPANSION -below), the -\fIhistory expansion\fP character, usually \fB!\fP, must be quoted -to prevent history expansion. -.PP -There are three quoting mechanisms: the -.IR "escape character" , -single quotes, and double quotes. -.PP -A non-quoted backslash (\fB\e\fP) is the -.IR "escape character" . -It preserves the literal value of the next character that follows, -with the exception of <newline>. If a \fB\e\fP<newline> pair -appears, and the backslash is not itself quoted, the \fB\e\fP<newline> -is treated as a line continuation (that is, it is removed from the -input stream and effectively ignored). -.PP -Enclosing characters in single quotes preserves the literal value -of each character within the quotes. A single quote may not occur -between single quotes, even when preceded by a backslash. -.PP -Enclosing characters in double quotes preserves the literal value -of all characters within the quotes, with the exception of -.BR $ , -.BR \` , -.BR \e , -and, when history expansion is enabled, -.BR ! . -The characters -.B $ -and -.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 \` , -\^\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 * -and -.B @ -have special meaning when in double -quotes (see -.SM -.B PARAMETERS -below). -.PP -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 specified by the ANSI C standard. Backslash escape sequences, if -present, are decoded as follows: -.RS -.PD 0 -.TP -.B \ea -alert (bell) -.TP -.B \eb -backspace -.TP -.B \ee -.TP -.B \eE -an escape character -.TP -.B \ef -form feed -.TP -.B \en -new line -.TP -.B \er -carriage return -.TP -.B \et -horizontal tab -.TP -.B \ev -vertical tab -.TP -.B \e\e -backslash -.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 -(one to three digits) -.TP -.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) -.TP -.B \ec\fIx\fP -a control-\fIx\fP character -.PD -.RE -.LP -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\(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 -double-quoted. -.SH PARAMETERS -A -.I parameter -is an entity that stores values. -It can be a -.IR name , -a number, or one of the special characters listed below under -.BR "Special Parameters" . -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 -the -.B unset -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.PP -A -.I variable -may be assigned to by a statement of the form -.RS -.PP -\fIname\fP=[\fIvalue\fP] -.RE -.PP -If -.I value -is not given, the variable is assigned the null string. All -.I values -undergo tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, and quote -removal (see -.SM -.B EXPANSION -below). If the variable has its -.B integer -attribute set, then -.I value -is evaluated as an arithmetic expression even if the $((...)) expansion is -not used (see -.B "Arithmetic Expansion" -below). -Word splitting is not performed, with the exception -of \fB"$@"\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 (\fIdeclaration\fP commands). -When in \fIposix mode\fP, these builtins may appear in a command after -one or more instances of the \fBcommand\fP builtin and retain these -assignment statement properties. -.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. -This includes arguments to builtin commands such as \fBdeclare\fP that -accept assignment statements (\fIdeclaration\fP commands). -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 -.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. -.PP -A variable can be assigned the \fInameref\fP attribute using the -\fB\-n\fP option to the \fBdeclare\fP or \fBlocal\fP builtin commands -(see the descriptions of \fBdeclare\fP and \fBlocal\fP below) -to create a \fInameref\fP, or a reference to another variable. -This allows variables to be manipulated indirectly. -Whenever the nameref variable is referenced, assigned to, unset, or has -its attributes modified (other than the \fInameref\P attribute itself), the -operation is actually performed on the variable specified by the nameref -variable's value. -A nameref is commonly used within shell functions to refer to a variable -whose name is passed as an argument to the function. -For instance, if a variable name is passed to a shell function as its first -argument, running -.sp .5 -.RS -.if t \f(CWdeclare -n ref=$1\fP -.if n declare -n ref=$1 -.RE -.sp .5 -inside the function creates a nameref variable \fBref\fP whose value is -the variable name passed as the first argument. -References and assignments to \fBref\fP, and changes to its attributes, -are treated as references, assignments, and attribute modifications -to the variable whose name was passed as \fB$1\fP. -If the control variable in a \fBfor\fP loop has the nameref attribute, -the list of words can be a list of shell variables, and a name reference -will be established for each word in the list, in turn, when the loop is -executed. -Array variables cannot be given the \fB\nameref\fP attribute. -However, nameref variables can reference array variables and subscripted -array variables. -Namerefs can be unset using the \fB\-n\fP option to the \fBunset\fP builtin. -Otherwise, if \fBunset\fP is executed with the name of a nameref variable -as an argument, the variable referenced by the nameref variable will be unset. -.SS Positional Parameters -.PP -A -.I positional parameter -is a parameter denoted by one or more -digits, other than the single digit 0. Positional parameters are -assigned from the shell's arguments when it is invoked, -and may be reassigned using the -.B set -builtin command. Positional parameters may not be assigned to -with assignment statements. The positional parameters are -temporarily replaced when a shell function is executed (see -.SM -.B FUNCTIONS -below). -.PP -When a positional parameter consisting of more than a single -digit is expanded, it must be enclosed in braces (see -.SM -.B EXPANSION -below). -.SS Special Parameters -.PP -The shell treats several parameters specially. These parameters may -only be referenced; assignment to them is not allowed. -.PD 0 -.TP -.B * -Expands to the positional parameters, starting from one. -When the expansion is not within double quotes, each positional parameter -expands to a separate word. -In contexts where it is performed, those words -are subject to further word splitting and pathname expansion. -When the expansion occurs within double quotes, it expands to a single word -with the value of each parameter separated by the first character -of the -.SM -.B IFS -special variable. That is, "\fB$*\fP" is equivalent -to "\fB$1\fP\fIc\fP\fB$2\fP\fIc\fP\fB...\fP", where -.I c -is the first character of the value of the -.SM -.B IFS -variable. If -.SM -.B IFS -is unset, the parameters are separated by spaces. -If -.SM -.B IFS -is null, the parameters are joined without intervening separators. -.TP -.B @ -Expands to the positional parameters, starting from one. When the -expansion occurs within double quotes, each parameter expands to a -separate word. That is, "\fB$@\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). -.TP -.B # -Expands to the number of positional parameters in decimal. -.TP -.B ? -Expands to the exit status of the most recently executed foreground -pipeline. -.TP -.B \- -Expands to the current option flags as specified upon invocation, -by the -.B set -builtin command, or those set by the shell itself -(such as the -.B \-i -option). -.TP -.B $ -Expands to the process ID of the shell. In a () subshell, it -expands to the process ID of the current shell, not the -subshell. -.TP -.B ! -Expands to the process ID of the job most recently placed into the -background, whether executed as an asynchronous command or using -the \fBbg\fP builtin (see -.SM -.B "JOB CONTROL" -below). -.TP -.B 0 -Expands to the name of the shell or shell script. This is set at -shell initialization. If -.B bash -is invoked with a file of commands, -.B $0 -is set to the name of that file. If -.B bash -is started with the -.B \-c -option, then -.B $0 -is set to the first argument after the string to be -executed, if one is present. Otherwise, it is set -to the filename used to invoke -.BR bash , -as given by argument zero. -.TP -.B _ -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 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 -.SS Shell Variables -.PP -The following variables are set by the shell: -.PP -.PD 0 -.TP -.B BASH -Expands to the full filename 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. -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 -.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 -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 -.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 -.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 -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 (\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). -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 -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 -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 within each subshell or subshell environment when -the shell begins executing in that environment. -The initial value is 0. -.TP -.B BASH_VERSINFO -A readonly array variable whose members hold version information for -this instance of -.BR bash . -The values assigned to the array members are as follows: -.sp .5 -.RS -.TP 24 -.B BASH_VERSINFO[\fR0\fP] -The major version number (the \fIrelease\fP). -.TP -.B BASH_VERSINFO[\fR1\fP] -The minor version number (the \fIversion\fP). -.TP -.B BASH_VERSINFO[\fR2\fP] -The patch level. -.TP -.B BASH_VERSINFO[\fR3\fP] -The build version. -.TP -.B BASH_VERSINFO[\fR4\fP] -The release status (e.g., \fIbeta1\fP). -.TP -.B BASH_VERSINFO[\fR5\fP] -The value of -.SM -.BR MACHTYPE . -.RE -.TP -.B BASH_VERSION -Expands to a string describing the version of this instance of -.BR bash . -.TP -.B COMP_CWORD -An index into \fB${COMP_WORDS}\fP of the word containing the current -cursor position. -This variable is available only in shell functions invoked by the -programmable completion facilities (see \fBProgrammable Completion\fP -below). -.TP -.B COMP_KEY -The key (or final key of a key sequence) used to invoke the current -completion function. -.TP -.B COMP_LINE -The current command line. -This variable is available only in shell functions and external -commands invoked by the -programmable completion facilities (see \fBProgrammable Completion\fP -below). -.TP -.B COMP_POINT -The index of the current cursor position relative to the beginning of -the current command. -If the current cursor position is at the end of the current command, -the value of this variable is equal to \fB${#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 \fBreadline\fP library treats as word -separators when performing word completion. -If -.SM -.B COMP_WORDBREAKS -is unset, it loses its special properties, even if it is -subsequently reset. -.TP -.B COMP_WORDS -An array variable (see \fBArrays\fP below) consisting of the individual -words in the current command line. -The 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 -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 DIRSTACK -is unset, it loses its special properties, even if it is -subsequently reset. -.TP -.B EUID -Expands to the effective user ID of the current user, initialized at -shell startup. This variable is readonly. -.TP -.B FUNCNAME -An array variable containing the names of all shell functions -currently in the execution call stack. -The element with index 0 is the name of any currently-executing -shell function. -The bottom-most element (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. -Assignments to -.SM -.B FUNCNAME -have no effect and return an error status. -If -.SM -.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 -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 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 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 -command. -.TP -.B OPTARG -The value of the last option argument processed by the -.B getopts -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.TP -.B OPTIND -The index of the next argument to be processed by the -.B getopts -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.TP -.B OSTYPE -Automatically set to a string that -describes the operating system on which -.B bash -is executing. -The default is system-dependent. -.TP -.B PIPESTATUS -An array variable (see -.B Arrays -below) containing a list of exit status values from the processes -in the most-recently-executed foreground pipeline (which may -contain only a single command). -.TP -.B PPID -The process ID of the shell's parent. This variable is readonly. -.TP -.B PWD -The current working directory as set by the -.B cd -command. -.TP -.B RANDOM -Each time this parameter is referenced, a random integer between -0 and 32767 is -generated. The sequence of random numbers may be initialized by assigning -a value to -.SM -.BR RANDOM . -If -.SM -.B RANDOM -is unset, it loses its special properties, even if it is -subsequently reset. -.TP -.B 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 -builtin command when no arguments are supplied. -.TP -.B SECONDS -Each time this parameter is -referenced, the number of seconds since shell invocation is returned. If a -value is assigned to -.SM -.BR SECONDS , -the value returned upon subsequent -references is -the number of seconds since the assignment plus the value assigned. -If -.SM -.B SECONDS -is unset, it loses its special properties, even if it is -subsequently reset. -.TP -.B SHELLOPTS -A colon-separated list of enabled shell options. Each word in -the list is a valid argument for the -.B \-o -option to the -.B set -builtin command (see -.SM -.B "SHELL BUILTIN COMMANDS" -below). The options appearing in -.SM -.B SHELLOPTS -are those reported as -.I on -by \fBset \-o\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 SHLVL -Incremented by one each time an instance of -.B bash -is started. -.TP -.B UID -Expands to the user ID of the current user, initialized at shell startup. -This variable is readonly. -.PD -.PP -The following variables are used by the shell. In some cases, -.B bash -assigns a default value to a variable; these cases are noted -below. -.PP -.PD 0 -.TP -.B BASH_COMPAT -The value is used to set the shell's compatibility level. -See the description of the \fBshopt\fP builtin below under -\fBSHELL BUILTIN COMMANDS\fP -for a description of the various compatibility -levels and their effects. -The value may be a decimal number (e.g., 4.2) or an integer (e.g., 42) -corresponding to the desired compatibility level. -If \fBBASH_COMPAT\fP is unset or set to the empty string, the compatibility -level is set to the default for the current version. -If \fBBASH_COMPAT\fP is set to a value that is not one of the valid -compatibility levels, the shell prints an error message and sets the -compatibility level to the default for the current version. -The valid compatibility levels correspond to the compatibility options -accepted by the \fBshopt\fP builtin described below (for example, -\fBcompat42\fP means that 4.2 and 42 are valid values). -The current version is also a valid value. -.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 -initialize the shell, as in -.IR ~/.bashrc . -The value of -.SM -.B BASH_ENV -is subjected to parameter expansion, command substitution, and arithmetic -expansion before being interpreted as a filename. -.SM -.B PATH -is not used to search for the resultant filename. -.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 -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 CHILD_MAX -Set the number of exited child status values for the shell to remember. -Bash will not allow this value to be decreased below a POSIX-mandated -minimum, and there is a maximum value (currently 8192) that this may -not exceed. -The minimum value is system-dependent. -.TP -.B COLUMNS -Used by the \fBselect\fP compound command to determine the terminal width -when printing selection lists. -Automatically set if the -.B checkwinsize -option is enabled or in an interactive shell upon receipt of a -.SM -.BR SIGWINCH . -.TP -.B COMPREPLY -An array variable from which \fBbash\fP reads the possible completions -generated by a shell function invoked by the programmable completion -facility (see \fBProgrammable Completion\fP below). -Each array element contains one possible completion. -.TP -.B EMACS -If \fBbash\fP finds this variable in the environment when the shell starts -with value -.if t \f(CWt\fP, -.if n "t", -it assumes that the shell is running in an Emacs shell buffer and disables -line editing. -.TP -.B 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 -builtin command. -.TP -.B FIGNORE -A colon-separated list of suffixes to ignore when performing -filename completion (see -.SM -.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 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. -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. -.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 -.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 -The name of the file in which command history is saved (see -.SM -.B HISTORY -below). The default value is \fI~/.bash_history\fP. If unset, the -command history is not saved when a shell exits. -.TP -.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 by removing the oldest entries. -The history file is also truncated to this size after -writing it when a shell exits. -If the value is 0, the history file is truncated to zero size. -Non-numeric values and numeric values less than zero inhibit truncation. -The shell sets the default value to the value of \fBHISTSIZE\fP -after reading any startup files. -.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 -.SM -.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 -.SM -.BR HISTIGNORE . -.TP -.B HISTSIZE -The number of commands to remember in the command history (see -.SM -.B HISTORY -below). -If the value is 0, commands are not saved in the history list. -Numeric values less than zero result in every command being saved -on the history list (there is no limit). -The shell sets the default value to 500 after reading any startup files. -.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 -adds the contents of the new file to the existing list. -If -.SM -.B HOSTFILE -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 -.SM -.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 -selected with a variable starting with \fBLC_\fP. -.TP -.B LC_ALL -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 collation order used when sorting the -results of pathname expansion, and determines the behavior of range -expressions, equivalence classes, and collating sequences within -pathname expansion and pattern matching. -.TP -.B LC_CTYPE -This variable determines the interpretation of characters and the -behavior of character classes within pathname expansion and pattern -matching. -.TP -.B LC_MESSAGES -This variable determines the locale used to translate double-quoted -strings preceded by a \fB$\fP. -.TP -.B LC_NUMERIC -This variable determines the locale category used for number formatting. -.TP -.B LINES -Used by the \fBselect\fP compound command to determine the column length -for printing selection lists. -Automatically set if the -.B checkwinsize -option is enabled or in an interactive shell upon receipt of a -.SM -.BR SIGWINCH . -.TP -.B MAIL -If this parameter is set to a file or directory name and the -.SM -.B MAILPATH -variable is not set, -.B bash -informs the user of the arrival of mail in the specified file or -Maildir-format directory. -.TP -.B MAILCHECK -Specifies how -often (in seconds) -.B bash -checks for mail. The default is 60 seconds. When it is time to check -for mail, the shell does so before displaying the primary prompt. -If this variable is unset, or set to a value that is not a number -greater than or equal to zero, the shell disables mail checking. -.TP -.B MAILPATH -A colon-separated list of filenames to be checked for mail. -The message to be printed when mail arrives in a particular file -may be specified by separating the filename from the message with a `?'. -When used in the text of the message, \fB$_\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$USER\fP). -.RE -.TP -.B OPTERR -If set to the value 1, -.B bash -displays error messages generated by the -.B getopts -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.SM -.B OPTERR -is initialized to 1 each time the shell is invoked or a shell -script is executed. -.TP -.B PATH -The search path for commands. It -is a colon-separated list of directories in which -the shell looks for commands (see -.SM -.B COMMAND EXECUTION -below). -A zero-length (null) directory name in the value of -.SM -.B PATH -indicates the current directory. -A null directory name may appear as two adjacent colons, or as an initial -or trailing colon. -The default path is system-dependent, -and is set by the administrator who installs -.BR bash . -A common value is -.if t \f(CW/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin\fP. -.if n ``/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin''. -.TP -.B POSIXLY_CORRECT -If this variable is in the environment when \fBbash\fP starts, the shell -enters \fIposix mode\fP before reading the startup files, as if the -.B \-\-posix -invocation option had been supplied. If it is set while the shell is -running, \fBbash\fP enables \fIposix mode\fP, as if the command -.if t \f(CWset -o posix\fP -.if n \fIset -o posix\fP -had been executed. -.TP -.B PROMPT_COMMAND -If set, the value is executed as a command prior to issuing each primary -prompt. -.TP -.B PROMPT_DIRTRIM -If set to a number greater than zero, the value is used as the number of -trailing directory components to retain when expanding the \fB\ew\fP and -\fB\eW\fP prompt string escapes (see -.SM -.B PROMPTING -below). Characters removed are replaced with an ellipsis. -.TP -.B PS1 -The value of this parameter is expanded (see -.SM -.B PROMPTING -below) and used as the primary prompt string. The default value is -``\fB\es\-\ev\e$ \fP''. -.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 PS3 -The value of this parameter is used as the prompt for the -.B select -command (see -.SM -.B SHELL GRAMMAR -above). -.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 -displays during an execution trace. The first character of -.SM -.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\et%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, -.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 -.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 a line of input after issuing the -primary prompt. -.B Bash -terminates after waiting for that number of seconds if a complete -line of 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 -job control. If this variable is set, single word simple -commands without redirections are treated as candidates for resumption -of an existing stopped job. There is no ambiguity allowed; if there is -more than one job beginning with the string typed, the job most recently -accessed is selected. The -.I name -of a stopped job, in this context, is the command line used to -start it. -If set to the value -.IR exact , -the string supplied must match the name of a stopped job exactly; -if set to -.IR substring , -the string supplied needs to match a substring of the name of a -stopped job. The -.I substring -value provides functionality analogous to the -.B %? -job identifier (see -.SM -.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 \fB%\fP\fIstring\fP job identifier. -.TP -.B histchars -The two or three characters which control history expansion -and tokenization (see -.SM -.B HISTORY EXPANSION -below). The first character is the \fIhistory expansion\fP character, -the character which signals the start of a history -expansion, normally `\fB!\fP'. -The second character is the \fIquick substitution\fP -character, which is used as shorthand for re-running the previous -command entered, substituting one string for another in the command. -The default is `\fB^\fP'. -The optional third character is the character -which indicates that the remainder of the line is a comment when found -as the first character of a word, normally `\fB#\fP'. The history -comment character causes history substitution to be skipped for the -remaining words on the line. It does not necessarily cause the shell -parser to treat the rest of the line as a comment. -.PD -.SS Arrays -.B Bash -provides one-dimensional 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 -limit on the size of an array, nor any requirement that members -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. -Unless otherwise noted, indexed array indices must be non-negative integers. -.PP -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. -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. -.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 -.B readonly -builtins. Each attribute applies to all members of an array. -.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. -Indexed array assignments do not require anything but \fIstring\fP. -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 -\fIname\fP[\fIsubscript\fP]=\fIvalue\fP syntax introduced above. -When assigning to an indexed array, if -.I name -is subscripted by a negative number, that number is -interpreted as relative to one greater than the maximum index of -\fIname\fP, so negative indices count back from the end of the -array, and an index of \-1 references the last element. -.PP -Any element of an array may be referenced using -${\fIname\fP[\fIsubscript\fP]}. The braces are required to avoid -conflicts with pathname expansion. If -\fIsubscript\fP is \fB@\fP or \fB*\fP, the word expands to -all members of \fIname\fP. These subscripts differ only when the -word appears within double quotes. If the word is double-quoted, -${\fIname\fP[*]} expands to a single -word with the value of each array member separated by the first -character of the -.SM -.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. -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 the array with a subscript of 0. -If the -.I subscript -used to reference an element of an indexed array -evaluates to a number less than zero, it is -interpreted as relative to one greater than the maximum index of the array, -so negative indices count back from the end of the -array, and an index of \-1 references the last element. -.PP -An array variable is considered set if a subscript has been assigned a -value. The null string is a valid value. -.PP -It is possible to obtain the keys (indices) of an array as well as the values. -${\fB!\fP\fIname\fP[\fI@\fP]} and ${\fB!\fP\fIname\fP[\fI*\fP]} -expand to the indices assigned in array variable \fIname\fP. -The treatment when in double quotes is similar to the expansion of the -special parameters \fI@\fP and \fI*\fP within double quotes. -.PP -The -.B unset -builtin is used to destroy arrays. \fBunset\fP \fIname\fP[\fIsubscript\fP] -destroys the array element at index \fIsubscript\fP. -Negative subscripts to indexed arrays are interpreted as described above. -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. -.PP -The -.BR declare , -.BR local , -and -.B readonly -builtins each accept a -.B \-a -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 -.B \-a -option to assign a list of words read from the standard input -to an array. The -.B set -and -.B declare -builtins display array values in a way that allows them to be -reused as assignments. -.SH EXPANSION -Expansion is performed on the command line after it has been split into -words. There are seven kinds of expansion performed: -.IR "brace expansion" , -.IR "tilde expansion" , -.IR "parameter and variable expansion" , -.IR "command substitution" , -.IR "arithmetic expansion" , -.IR "word splitting" , -and -.IR "pathname expansion" . -.PP -The order of expansions is: -brace expansion; -tilde expansion, parameter and variable expansion, arithmetic expansion, -and command substitution (done in a left-to-right fashion); -word splitting; -and pathname expansion. -.PP -On systems that can support it, there is an additional expansion -available: \fIprocess substitution\fP. -This is performed at the -same time as tilde, parameter, variable, and arithmetic expansion and -command substitution. -.PP -Only brace expansion, word splitting, and pathname expansion -can change the number of words of the expansion; other expansions -expand a single word to a single word. -The only exceptions to this are the expansions of -"\fB$@\fP" and "\fB${\fP\fIname\fP\fB[@]}\fP" -as explained above (see -.SM -.BR PARAMETERS ). -.SS Brace Expansion -.PP -.I "Brace expansion" -is a mechanism by which arbitrary strings -may be generated. This mechanism is similar to -\fIpathname expansion\fP, but the filenames generated -need not exist. Patterns to be brace expanded take -the form of an optional -.IR preamble , -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 -to each resulting string, expanding left to right. -.PP -Brace expansions may be nested. The results of each expanded -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, -using the default C locale. -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. -.B Bash -does not apply any syntactic interpretation to the context of the -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 or a valid -sequence expression. -Any incorrectly formed brace expansion is left unchanged. -A \fB{\fP or \fB,\fP may be quoted with a backslash to prevent its -being considered part of a brace expression. -To avoid conflicts with parameter expansion, the string \fB${\fP -is not considered eligible for brace expansion. -.PP -This construct is typically used as shorthand when the common -prefix of the strings to be generated is longer than in the -above example: -.RS -.PP -mkdir /usr/local/src/bash/{old,new,dist,bugs} -.RE -or -.RS -chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} -.RE -.PP -Brace expansion introduces a slight incompatibility with -historical versions of -.BR sh . -.B sh -does not treat opening or closing braces specially when they -appear as part of a word, and preserves them in the output. -.B Bash -removes braces from words as a consequence of brace -expansion. For example, a word entered to -.B sh -as \fIfile{1,2}\fP -appears identically in the output. The same word is -output as -.I file1 file2 -after expansion by -.BR bash . -If strict compatibility with -.B sh -is desired, start -.B bash -with the -.B +B -option or disable brace expansion with the -.B +B -option to the -.B set -command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.SS Tilde Expansion -.PP -If a word begins with an unquoted tilde character (`\fB~\fP'), all of -the characters preceding the first unquoted slash (or all characters, -if there is no unquoted slash) are considered a \fItilde-prefix\fP. -If none of the characters in the tilde-prefix are quoted, the -characters in the tilde-prefix following the tilde are treated as a -possible \fIlogin name\fP. -If this login name is the null string, the tilde is replaced with the -value of the shell parameter -.SM -.BR HOME . -If -.SM -.B HOME -is unset, the home directory of the user executing the shell is -substituted instead. -Otherwise, the tilde-prefix is replaced with the home directory -associated with the specified login name. -.PP -If the tilde-prefix is a `~+', the value of the shell variable -.SM -.B PWD -replaces the tilde-prefix. -If the tilde-prefix is a `~\-', the value of the shell variable -.SM -.BR OLDPWD , -if it is set, is substituted. -If the characters following the tilde in the tilde-prefix consist -of a number \fIN\fP, optionally prefixed -by a `+' or a `\-', the tilde-prefix is replaced with the corresponding -element from the directory stack, as it would be displayed by the -.B dirs -builtin invoked with the tilde-prefix as an argument. -If the characters following the tilde in the tilde-prefix consist of a -number without a leading `+' or `\-', `+' is assumed. -.PP -If the login name is invalid, or the tilde expansion fails, the word -is unchanged. -.PP -Each variable assignment is checked for unquoted tilde-prefixes immediately -following a -.B : -or the first -.BR = . -In these cases, tilde expansion is also performed. -Consequently, one may use filenames with tildes in assignments to -.SM -.BR PATH , -.SM -.BR MAILPATH , -and -.SM -.BR CDPATH , -and the shell assigns the expanded value. -.SS Parameter Expansion -.PP -The `\fB$\fP' character introduces parameter expansion, -command substitution, or arithmetic expansion. The parameter name -or symbol to be expanded may be enclosed in braces, which -are optional but serve to protect the variable to be expanded from -characters immediately following it which could be -interpreted as part of the name. -.PP -When braces are used, the matching ending brace is the first `\fB}\fP' -not escaped by a backslash or within a quoted string, and not within an -embedded arithmetic expansion, command substitution, or parameter -expansion. -.PP -.PD 0 -.TP -${\fIparameter\fP} -The value of \fIparameter\fP is substituted. The braces are required -when -.I parameter -is a positional parameter with more than one digit, -or when -.I parameter -is followed by a character which is not to be -interpreted as part of its name. -The \fIparameter\fP is a shell parameter as described above -\fBPARAMETERS\fP) or an array reference (\fBArrays\fP). -.PD -.PP -If the first character of \fIparameter\fP is an exclamation point (\fB!\fP), -it introduces a level of variable indirection. -\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 ${\fB!\fP\fIprefix\fP\fB*\fP} and -${\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. -.PP -When not performing substring expansion, using the forms documented below -(e.g., \fB:-\fP), -\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 -${\fIparameter\fP\fB:\-\fP\fIword\fP} -\fBUse Default Values\fP. If -.I parameter -is unset or null, the expansion of -.I word -is substituted. Otherwise, the value of -.I parameter -is substituted. -.TP -${\fIparameter\fP\fB:=\fP\fIword\fP} -\fBAssign Default Values\fP. -If -.I parameter -is unset or null, the expansion of -.I word -is assigned to -.IR parameter . -The value of -.I parameter -is then substituted. Positional parameters and special parameters may -not be assigned to in this way. -.TP -${\fIparameter\fP\fB:?\fP\fIword\fP} -\fBDisplay Error if Null or Unset\fP. -If -.I parameter -is null or unset, the expansion of \fIword\fP (or a message to that effect -if -.I word -is not present) is written to the standard error and the shell, if it -is not interactive, exits. Otherwise, the value of \fIparameter\fP is -substituted. -.TP -${\fIparameter\fP\fB:+\fP\fIword\fP} -\fBUse Alternate Value\fP. -If -.I parameter -is null or unset, nothing is substituted, otherwise the expansion of -.I word -is substituted. -.TP -${\fIparameter\fP\fB:\fP\fIoffset\fP} -.PD 0 -.TP -${\fIparameter\fP\fB:\fP\fIoffset\fP\fB:\fP\fIlength\fP} -.PD -\fBSubstring Expansion\fP. -Expands to up to \fIlength\fP characters of the value of \fIparameter\fP -starting at the character specified by \fIoffset\fP. -If \fIparameter\fP is \fB@\fP, an indexed array subscripted by -\fB@\fP or \fB*\fP, or an associative array name, the results differ as -described below. -If \fIlength\fP is omitted, expands to the substring of the value of -\fIparameter\fP starting at the character specified by \fIoffset\fP -and extending to the end of the value. -\fIlength\fP and \fIoffset\fP are arithmetic expressions (see -.SM -.B -ARITHMETIC EVALUATION -below). -.sp 1 -If \fIoffset\fP evaluates to a number less than zero, the value -is used as an offset in characters -from the end of the value of \fIparameter\fP. -If \fIlength\fP evaluates to a number less than zero, -it is interpreted as an offset in characters -from the end of the value of \fIparameter\fP rather than -a number of characters, and the expansion is the characters between -\fIoffset\fP and that result. -Note that a negative offset must be separated from the colon by at least -one space to avoid being confused with the \fB:-\fP expansion. -.sp 1 -If \fIparameter\fP is \fB@\fP, the result is \fIlength\fP positional -parameters beginning at \fIoffset\fP. -A negative \fIoffset\fP is taken relative to one greater than the greatest -positional parameter, so an offset of -1 evaluates to the last positional -parameter. -It is an expansion error if \fIlength\fP evaluates to a number less than -zero. -.sp 1 -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. -It is an expansion error if \fIlength\fP evaluates to a number less than -zero. -.sp 1 -Substring expansion applied to an associative array produces undefined -results. -.sp 1 -Substring indexing is zero-based unless the positional parameters -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 -is -.B * -or -.BR @ , -the value substituted is the number of positional parameters. -If -.I parameter -is an array name subscripted by -.B * -or -.BR @ , -the value substituted is the number of elements in the array. -If -.I parameter -is an indexed array name subscripted by a negative number, that number is -interpreted as relative to one greater than the maximum index of -\fIparameter\fP, so negative indices count back from the end of the -array, and an index of \-1 references the last element. -.TP -${\fIparameter\fP\fB#\fP\fIword\fP} -.PD 0 -.TP -${\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 -expansion. If the pattern matches the beginning of -the value of -.IR parameter , -then the result of the expansion is the expanded value of -.I parameter -with the shortest matching pattern (the ``\fB#\fP'' case) or the -longest matching pattern (the ``\fB##\fP'' case) deleted. -If -.I parameter -is -.B @ -or -.BR * , -the pattern removal 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 pattern removal operation is applied to each member of the -array in turn, and the expansion is the resultant list. -.TP -${\fIparameter\fP\fB%\fP\fIword\fP} -.PD 0 -.TP -${\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 -.IR parameter , -then the result of the expansion is the expanded value of -.I parameter -with the shortest matching pattern (the ``\fB%\fP'' case) or the -longest matching pattern (the ``\fB%%\fP'' case) deleted. -If -.I parameter -is -.B @ -or -.BR * , -the pattern removal 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 pattern removal operation is applied to each member of the -array in turn, and the expansion is the resultant list. -.TP -${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP} -\fBPattern substitution\fP. -The \fIpattern\fP is expanded to produce a pattern just as in -pathname expansion. -\fIParameter\fP is expanded and the longest match of \fIpattern\fP -against its value is replaced with \fIstring\fP. -If \fIpattern\fP begins with \fB/\fP, all matches of \fIpattern\fP are -replaced with \fIstring\fP. Normally only the first match is replaced. -If \fIpattern\fP begins with \fB#\fP, it must match at the beginning -of the expanded value of \fIparameter\fP. -If \fIpattern\fP begins with \fB%\fP, it must match at the end -of the expanded value of \fIparameter\fP. -If \fIstring\fP is null, matches of \fIpattern\fP are deleted -and the \fB/\fP following \fIpattern\fP may be omitted. -If -.I parameter -is -.B @ -or -.BR * , -the substitution operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -.I parameter -is an array variable subscripted with -.B @ -or -.BR * , -the substitution operation is applied to each member of the -array in turn, and the expansion is the resultant list. -.TP -${\fIparameter\fP\fB^\fP\fIpattern\fP} -.PD 0 -.TP -${\fIparameter\fP\fB^^\fP\fIpattern\fP} -.TP -${\fIparameter\fP\fB,\fP\fIpattern\fP} -.TP -${\fIparameter\fP\fB,,\fP\fIpattern\fP} -.PD -\fBCase modification\fP. -This expansion modifies the case of alphabetic characters in \fIparameter\fP. -The \fIpattern\fP is expanded to produce a pattern just as in -pathname expansion. -Each character in the expanded value of \fIparameter\fP is tested against -\fIpattern\fP, and, if it matches the pattern, its case is converted. -The pattern should not attempt to match more than one character. -The \fB^\fP operator converts lowercase letters matching \fIpattern\fP -to uppercase; the \fB,\fP operator converts matching uppercase letters -to lowercase. -The \fB^^\fP and \fB,,\fP expansions convert each matched character in the -expanded value; the \fB^\fP and \fB,\fP expansions match and convert only -the first character in the expanded value. -If \fIpattern\fP is omitted, it is treated like a \fB?\fP, which matches -every character. -If -.I parameter -is -.B @ -or -.BR * , -the case modification operation is applied to each positional -parameter in turn, and the expansion is the resultant list. -If -.I parameter -is an array variable subscripted with -.B @ -or -.BR * , -the case modification operation is applied to each member of the -array in turn, and the expansion is the resultant list. -.SS Command Substitution -.PP -\fICommand substitution\fP allows the output of a command to replace -the command name. There are two forms: -.RS -.PP -\fB$(\fP\fIcommand\fP\|\fB)\fP -.RE -or -.RS -\fB\`\fP\fIcommand\fP\fB\`\fP -.RE -.PP -.B Bash -performs the expansion by executing \fIcommand\fP and -replacing the command substitution with the standard output of the -command, with any trailing newlines deleted. -Embedded newlines are not deleted, but they may be removed during -word splitting. -The command substitution \fB$(cat \fIfile\fP)\fR can be replaced by -the equivalent but faster \fB$(< \fIfile\fP)\fR. -.PP -When the old-style backquote form of substitution is used, -backslash retains its literal meaning except when followed by -.BR $ , -.BR \` , -or -.BR \e . -The first backquote not preceded by a backslash terminates the -command substitution. -When using the $(\^\fIcommand\fP\|) form, all characters between the -parentheses make up the command; none are treated specially. -.PP -Command substitutions may be nested. To nest when using the backquoted form, -escape the inner backquotes with backslashes. -.PP -If the substitution appears within double quotes, word splitting and -pathname expansion are not performed on the results. -.SS Arithmetic Expansion -.PP -Arithmetic expansion allows the evaluation of an arithmetic expression -and the substitution of the result. The format for arithmetic expansion is: -.RS -.PP -\fB$((\fP\fIexpression\fP\fB))\fP -.RE -.PP -The -.I expression -is treated as if it were within double quotes, but a double quote -inside the parentheses is not treated specially. -All tokens in the expression undergo parameter and variable expansion, -command substitution, and quote removal. -The result is treated as the arithmetic expression to be evaluated. -Arithmetic expansions may be nested. -.PP -The evaluation is performed according to the rules listed below under -.SM -.BR "ARITHMETIC EVALUATION" . -If -.I expression -is invalid, -.B bash -prints a message indicating failure and no substitution occurs. -.SS Process Substitution -.PP -\fIProcess substitution\fP is supported on systems that support named -pipes (\fIFIFOs\fP) or the \fB/dev/fd\fP method of naming open files. -It takes the form of -\fB<(\fP\fIlist\^\fP\fB)\fP -or -\fB>(\fP\fIlist\^\fP\fB)\fP. -The process \fIlist\fP is run with its input or output connected to a -\fIFIFO\fP or some file in \fB/dev/fd\fP. The name of this file is -passed as an argument to the current command as the result of the -expansion. If the \fB>(\fP\fIlist\^\fP\fB)\fP form is used, writing to -the file will provide input for \fIlist\fP. If the -\fB<(\fP\fIlist\^\fP\fB)\fP form is used, the file passed as an -argument should be read to obtain the output of \fIlist\fP. -.PP -When available, process substitution is performed -simultaneously with parameter and variable expansion, -command substitution, -and arithmetic expansion. -.SS Word Splitting -.PP -The shell scans the results of -parameter expansion, -command substitution, -and -arithmetic expansion -that did not occur within double quotes for -.IR "word splitting" . -.PP -The shell treats each character of -.SM -.B IFS -as a delimiter, and splits the results of the other -expansions into words using these characters as field terminators. -If -.SM -.B IFS -is unset, or its -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 not at the beginning or end serves to delimit words. -If -.SM -.B IFS -has a value other than the default, then sequences of -the whitespace characters -.B space -and -.B tab -are ignored at the beginning and end of the -word, as long as the whitespace character is in the -value of -.SM -.BR IFS -(an -.SM -.B IFS -whitespace character). -Any character in -.SM -.B IFS -that is not -.SM -.B IFS -whitespace, along with any adjacent -.SM -.B IFS -whitespace characters, delimits a field. -A sequence of -.SM -.B IFS -whitespace characters is also treated as a delimiter. -If the value of -.SM -.B IFS -is null, no word splitting occurs. -.PP -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 -null argument results and is retained. -.PP -Note that if no expansion occurs, no splitting -is performed. -.SS Pathname Expansion -.PP -After word splitting, -unless the -.B \-f -option has been set, -.B bash -scans each word for the characters -.BR * , -.BR ? , -and -.BR [ . -If one of these characters appears, then the word is -regarded as a -.IR pattern , -and replaced with an alphabetically sorted list of -filenames matching the pattern -(see -.SM -.B "Pattern Matching" -below). -If no matching filenames are found, -and the shell option -.B nullglob -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 -of alphabetic characters. -When a pattern is used for pathname expansion, -the character -.B ``.'' -at the start of a name or immediately following a slash -must be matched explicitly, unless the shell option -.B dotglob -is set. -When matching a pathname, the slash character must always be -matched explicitly. -In other cases, the -.B ``.'' -character is not treated specially. -See the description of -.B shopt -below under -.SM -.B SHELL BUILTIN COMMANDS -for a description of the -.BR nocaseglob , -.BR nullglob , -.BR failglob , -and -.B dotglob -shell options. -.PP -The -.SM -.B GLOBIGNORE -shell variable may be used to restrict the set of filenames matching a -.IR pattern . -If -.SM -.B GLOBIGNORE -is set, each matching filename that also matches one of the patterns in -.SM -.B GLOBIGNORE -is removed from the list of matches. -The filenames -.B ``.'' -and -.B ``..'' -are always ignored when -.SM -.B GLOBIGNORE -is set and not null. However, setting -.SM -.B GLOBIGNORE -to a non-null value has the effect of enabling the -.B dotglob -shell option, so all other filenames beginning with a -.B ``.'' -will match. -To get the old behavior of ignoring filenames beginning with a -.BR ``.'' , -make -.B ``.*'' -one of the patterns in -.SM -.BR GLOBIGNORE . -The -.B dotglob -option is disabled when -.SM -.B GLOBIGNORE -is unset. -.PP -\fBPattern Matching\fP -.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. 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: -.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 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 -and subdirectories. -.TP -.B ? -Matches any single character. -.TP -.B [...] -Matches any one of the enclosed characters. A pair of characters -separated by a hyphen denotes a -\fIrange expression\fP; -any character that falls between those two characters, inclusive, -using the current locale's collating sequence and character set, -is matched. If the first character following the -.B [ -is a -.B ! -or a -.B ^ -then any character not enclosed is matched. -The sorting order of characters in range expressions is determined by -the current locale and the values of the -.SM -.B LC_COLLATE -or -.SM -.B LC_ALL -shell variables, if set. -To obtain the traditional interpretation of range expressions, where -.B [a\-d] -is equivalent to -.BR [abcd] , -set value of the -.B LC_ALL -shell variable to -.BR C , -or enable the -.B globasciiranges -shell option. -A -.B \- -may be matched by including it as the first or last character -in the set. -A -.B ] -may be matched by including it as the first character -in the set. -.br -.if t .sp 0.5 -.if n .sp 1 -Within -.B [ -and -.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 standard: -.PP -.RS -.B -.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 -Within -.B [ -and -.BR ] , -an \fIequivalence class\fP can be specified using the syntax -\fB[=\fP\fIc\fP\fB=]\fP, which matches all characters with the -same collation weight (as defined by the current locale) as -the character \fIc\fP. -.br -.if t .sp 0.5 -.if n .sp 1 -Within -.B [ -and -.BR ] , -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 -builtin, several extended pattern matching operators are recognized. -In the following description, a \fIpattern-list\fP is a list of one -or more patterns separated by a \fB|\fP. -Composite patterns may be formed using one or more of the following -sub-patterns: -.sp 1 -.PD 0 -.RS -.TP -\fB?(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches zero or one occurrence of the given patterns -.TP -\fB*(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches zero or more occurrences of the given patterns -.TP -\fB+(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches one or more occurrences of the given patterns -.TP -\fB@(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches one of the given patterns -.TP -\fB!(\fP\^\fIpattern-list\^\fP\fB)\fP -Matches anything except one of the given patterns -.RE -.PD -.SS Quote Removal -.PP -After the preceding expansions, all unquoted occurrences of the -characters -.BR \e , -.BR \(aq , -and \^\f3"\fP\^ that did not result from one of the above -expansions are removed. -.SH REDIRECTION -Before a command is executed, its input and output -may be -.I redirected -using a special notation interpreted by the shell. -Redirection allows commands' file handles to be -duplicated, opened, closed, -made to refer to different files, -and can change the files the command reads from and writes to. -Redirection may also be used to modify file handles in the -current shell execution environment. -The following redirection -operators may precede or appear anywhere within a -.I simple command -or may follow a -.IR command . -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 or equal to 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 < , -the redirection refers to the standard input (file descriptor -0). If the first character of the redirection operator is -.BR > , -the redirection refers to the standard output (file descriptor -1). -.PP -The word following the redirection operator in the following -descriptions, unless otherwise noted, is subjected to -brace expansion, tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, quote removal, -pathname expansion, and word splitting. -If it expands to more than one word, -.B bash -reports an error. -.PP -Note that the order of redirections is significant. For example, -the command -.RS -.PP -ls \fB>\fP dirlist 2\fB>&\fP1 -.RE -.PP -directs both standard output and standard error to the file -.IR dirlist , -while the command -.RS -.PP -ls 2\fB>&\fP1 \fB>\fP dirlist -.RE -.PP -directs only the standard output to file -.IR dirlist , -because the standard error was duplicated from the standard output -before the standard output was redirected to -.IR dirlist . -.PP -\fBBash\fP handles several filenames specially when they are used in -redirections, as described in the following table: -.RS -.PP -.PD 0 -.TP -.B /dev/fd/\fIfd\fP -If \fIfd\fP is a valid integer, file descriptor \fIfd\fP is duplicated. -.TP -.B /dev/stdin -File descriptor 0 is duplicated. -.TP -.B /dev/stdout -File descriptor 1 is duplicated. -.TP -.B /dev/stderr -File descriptor 2 is duplicated. -.TP -.B /dev/tcp/\fIhost\fP/\fIport\fP -If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP -is an integer port number or service name, \fBbash\fP attempts to open -the corresponding TCP socket. -.TP -.B /dev/udp/\fIhost\fP/\fIport\fP -If \fIhost\fP is a valid hostname or Internet address, and \fIport\fP -is an integer port number or service name, \fBbash\fP attempts to open -the corresponding UDP 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 -the expansion of -.I word -to be opened for reading on file descriptor -.IR n , -or the standard input (file descriptor 0) if -.I n -is not specified. -.PP -The general format for redirecting input is: -.RS -.PP -[\fIn\fP]\fB<\fP\fIword\fP -.RE -.SS Redirecting Output -.PP -Redirection of output causes the file whose name results from -the expansion of -.I word -to be opened for writing on file descriptor -.IR n , -or the standard output (file descriptor 1) if -.I n -is not specified. If the file does not exist it is created; -if it does exist it is truncated to zero size. -.PP -The general format for redirecting output is: -.RS -.PP -[\fIn\fP]\fB>\fP\fIword\fP -.RE -.PP -If the redirection operator is -.BR > , -and the -.B noclobber -option to the -.B set -builtin has been enabled, the redirection will fail if the file -whose name results from the expansion of \fIword\fP exists and is -a regular file. -If the redirection operator is -.BR >| , -or the redirection operator is -.B > -and the -.B noclobber -option to the -.B set -builtin command is not enabled, the redirection is attempted even -if the file named by \fIword\fP exists. -.SS Appending Redirected Output -.PP -Redirection of output in this fashion -causes the file whose name results from -the expansion of -.I word -to be opened for appending on file descriptor -.IR n , -or the standard output (file descriptor 1) if -.I n -is not specified. If the file does not exist it is created. -.PP -The general format for appending output is: -.RS -.PP -[\fIn\fP]\fB>>\fP\fIword\fP -.RE -.PP -.SS Redirecting 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 redirected to the file whose name is the -expansion of -.IR word . -.PP -There are two formats for redirecting standard output and -standard error: -.RS -.PP -\fB&>\fP\fIword\fP -.RE -and -.RS -\fB>&\fP\fIword\fP -.RE -.PP -Of the two forms, the first is preferred. -This is semantically equivalent to -.RS -.PP -\fB>\fP\fIword\fP 2\fB>&\fP1 -.RE -.PP -When using the second form, \fIword\fP may not expand to a number or -\fB\-\fP. If it does, other redirection operators apply -(see \fBDuplicating File Descriptors\fP below) for compatibility -reasons. -.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 -.PP -(see \fBDuplicating File Descriptors\fP below). -.SS Here Documents -.PP -This type of redirection instructs the shell to read input from the -current source until a line containing only -.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: -.RS -.PP -.nf -\fB<<\fP[\fB\-\fP]\fIword\fP - \fIhere-document\fP -\fIdelimiter\fP -.fi -.RE -.PP -No parameter and variable expansion, command substitution, -arithmetic expansion, or pathname expansion is performed on -.IR word . -If any characters in -.I word -are quoted, the -.I delimiter -is the result of quote removal on -.IR word , -and the lines in the here-document are not expanded. -If \fIword\fP is unquoted, -all lines of the here-document are subjected to -parameter expansion, command substitution, and arithmetic expansion, -the character sequence -.B \e<newline> -is ignored, and -.B \e -must be used to quote the characters -.BR \e , -.BR $ , -and -.BR \` . -.PP -If the redirection operator is -.BR <<\- , -then all leading tab characters are stripped from input lines and the -line containing -.IR delimiter . -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 undergoes -brace expansion, tilde expansion, parameter and variable expansion, -command substitution, arithmetic expansion, and quote removal. -Pathname expansion and word splitting are not performed. -The result is supplied as a single string to the command on its -standard input. -.SS "Duplicating File Descriptors" -.PP -The redirection operator -.RS -.PP -[\fIn\fP]\fB<&\fP\fIword\fP -.RE -.PP -is used to duplicate input file descriptors. -If -.I word -expands to one or more digits, the file descriptor denoted by -.I n -is made to be a copy of that file descriptor. -If the digits in -.I word -do not specify a file descriptor open for input, a redirection error occurs. -If -.I word -evaluates to -.BR \- , -file descriptor -.I n -is closed. If -.I n -is not specified, the standard input (file descriptor 0) is used. -.PP -The operator -.RS -.PP -[\fIn\fP]\fB>&\fP\fIword\fP -.RE -.PP -is used similarly to duplicate output file descriptors. If -.I n -is not specified, the standard output (file descriptor 1) is used. -If the digits in -.I word -do not specify a file descriptor open for output, a redirection error occurs. -If -.I word -evaluates to -.BR \- , -file descriptor -.I n -is closed. -As a special case, if \fIn\fP is omitted, and \fIword\fP does not -expand to one or more digits or \fB\-\fP, 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 -.RS -.PP -[\fIn\fP]\fB<>\fP\fIword\fP -.RE -.PP -causes the file whose name is the expansion of -.I word -to be opened for both reading and writing on file descriptor -.IR n , -or on file descriptor 0 if -.I n -is not specified. If the file does not exist, it is created. -.SH ALIASES -\fIAliases\fP allow a string to be substituted for a word when it is used -as the first word of a simple command. -The shell maintains a list of aliases that may be set and unset with the -.B alias -and -.B unalias -builtin commands (see -.SM -.B SHELL BUILTIN COMMANDS -below). -The first word of each simple command, if unquoted, -is checked to see if it has an -alias. If so, that word is replaced by the text of the alias. -The characters \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 -.B ls -to -.BR "ls \-F" , -for instance, and -.B bash -does not try to recursively expand the replacement text. -If the last character of the alias value is a -.IR blank , -then the next command -word following the alias is also checked for alias expansion. -.PP -Aliases are created and listed with the -.B alias -command, and removed with the -.B unalias -command. -.PP -There is no mechanism for using arguments in the replacement text. -If arguments are needed, a shell function should be used (see -.SM -.B FUNCTIONS -below). -.PP -Aliases are not expanded when the shell is not interactive, unless -the -.B expand_aliases -shell option is set using -.B shopt -(see the description of -.B shopt -under -.SM -\fBSHELL BUILTIN COMMANDS\fP -below). -.PP -The rules concerning the definition and use of aliases are -somewhat confusing. -.B Bash -always reads at least one complete line -of input before executing any -of the commands on that line. Aliases are expanded when a -command is read, not when it is executed. Therefore, an -alias definition appearing on the same line as another -command does not take effect until the next line of input is read. -The commands following the alias definition -on that line are not affected by the new alias. -This behavior is also an issue when functions are executed. -Aliases are expanded when a function definition is read, -not when the function is executed, because a function definition -is itself a command. As a consequence, aliases -defined in a function are not available until after that -function is executed. To be safe, always put -alias definitions on a separate line, and do not use -.B alias -in compound commands. -.PP -For almost every purpose, aliases are superseded by -shell functions. -.SH FUNCTIONS -A shell function, defined as described above under -.SM -.BR "SHELL GRAMMAR" , -stores a series of commands for later execution. -When the name of a shell function is used as a simple command name, -the list of commands associated with that function name is executed. -Functions are executed in the context of the -current shell; no new process is created to interpret -them (contrast this with the execution of a shell script). -When a function is executed, the arguments to the -function become the positional parameters -during its execution. -The special parameter -.B # -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 these exceptions: the -.SM -.B DEBUG -and -.B RETURN -traps (see the description of the -.B trap -builtin under -.SM -.B SHELL BUILTIN COMMANDS -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), -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 -execution resumes with the next command after the function -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 -execution. -.PP -Function names and definitions may be listed with the -.B \-f -option to the -.B declare -or -.B typeset -builtin commands. The -.B \-F -option to -.B declare -or -.B typeset -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. -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 -commands and \fBArithmetic Expansion\fP). -Evaluation is done in fixed-width integers with no check for overflow, -though division by 0 is trapped and flagged as an error. -The operators and their precedence, associativity, and values -are the same as in the C language. -The following list of operators is grouped into levels of -equal-precedence operators. -The levels are listed in order of decreasing precedence. -.PP -.PD 0 -.TP -.B \fIid\fP++ \fIid\fP\-\- -variable post-increment and post-decrement -.TP -.B ++\fIid\fP \-\-\fIid\fP -variable pre-increment and pre-decrement -.TP -.B \- + -unary minus and plus -.TP -.B ! ~ -logical and bitwise negation -.TP -.B ** -exponentiation -.TP -.B * / % -multiplication, division, remainder -.TP -.B + \- -addition, subtraction -.TP -.B << >> -left and right bitwise shifts -.TP -.B <= >= < > -comparison -.TP -.B == != -equality and inequality -.TP -.B & -bitwise AND -.TP -.B ^ -bitwise exclusive OR -.TP -.B | -bitwise OR -.TP -.B && -logical AND -.TP -.B || -logical OR -.TP -.B \fIexpr\fP?\fIexpr\fP:\fIexpr\fP -conditional operator -.TP -.B = *= /= %= += \-= <<= >>= &= ^= |= -assignment -.TP -.B \fIexpr1\fP , \fIexpr2\fP -comma -.PD -.PP -Shell variables are allowed as operands; parameter expansion is -performed before the expression is evaluated. -Within an expression, shell variables may also be referenced by name -without using the parameter expansion syntax. -A shell variable that is null or unset evaluates to 0 when referenced -by name without using the parameter expansion syntax. -The value of a variable is evaluated as an arithmetic expression -when it is referenced, or when a variable which has been given the -\fIinteger\fP attribute using \fBdeclare -i\fP is assigned a value. -A null value evaluates to 0. -A shell variable need not have its \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 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. -When specifying \fIn\fP, -the digits greater< than 9 are represented by the lowercase letters, -the uppercase letters, @, and _, in that order. -If \fIbase\fP is less than or equal to 36, lowercase and uppercase -letters may be used interchangeably to represent numbers between 10 -and 35. -.PP -Operators are evaluated in order of precedence. Sub-expressions in -parentheses are evaluated first and may override the precedence -rules above. -.SH "CONDITIONAL EXPRESSIONS" -Conditional expressions are used by the \fB[[\fP compound command and -the \fBtest\fP and \fB[\fP builtin commands to test file attributes -and perform string and arithmetic comparisons. -Expressions are formed from the following unary or binary primaries. -If any \fIfile\fP argument to one of the primaries is of the form -\fI/dev/fd/n\fP, then file descriptor \fIn\fP is checked. -If the \fIfile\fP argument to one of the primaries is one of -\fI/dev/stdin\fP, \fI/dev/stdout\fP, or \fI/dev/stderr\fP, file -descriptor 0, 1, or 2, respectively, is checked. -.PP -Unless otherwise specified, primaries that operate on files follow symbolic -links and operate on the target of the link, rather than the link itself. -.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 \-a \fIfile\fP -True if \fIfile\fP exists. -.TP -.B \-b \fIfile\fP -True if \fIfile\fP exists and is a block special file. -.TP -.B \-c \fIfile\fP -True if \fIfile\fP exists and is a character special file. -.TP -.B \-d \fIfile\fP -True if \fIfile\fP exists and is a directory. -.TP -.B \-e \fIfile\fP -True if \fIfile\fP exists. -.TP -.B \-f \fIfile\fP -True if \fIfile\fP exists and is a regular file. -.TP -.B \-g \fIfile\fP -True if \fIfile\fP exists and is set-group-id. -.TP -.B \-h \fIfile\fP -True if \fIfile\fP exists and is a symbolic link. -.TP -.B \-k \fIfile\fP -True if \fIfile\fP exists and its ``sticky'' bit is set. -.TP -.B \-p \fIfile\fP -True if \fIfile\fP exists and is a named pipe (FIFO). -.TP -.B \-r \fIfile\fP -True if \fIfile\fP exists and is readable. -.TP -.B \-s \fIfile\fP -True if \fIfile\fP exists and has a size greater than zero. -.TP -.B \-t \fIfd\fP -True if file descriptor -.I fd -is open and refers to a terminal. -.TP -.B \-u \fIfile\fP -True if \fIfile\fP exists and its set-user-id bit is set. -.TP -.B \-w \fIfile\fP -True if \fIfile\fP exists and is writable. -.TP -.B \-x \fIfile\fP -True if \fIfile\fP exists and is executable. -.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 -\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, -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, or if \fIfile2\fP exists -and \fIfile1\fP does not. -.TP -.B \-o \fIoptname\fP -True if the shell option -.I optname -is enabled. -See the list of options under the description of the -.B \-o -option to 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 \-R \fIvarname\fP -True if the shell variable -.I varname -is set and is a name reference. -.TP -.B \-z \fIstring\fP -True if the length of \fIstring\fP is zero. -.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 -.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. -When used with the \fB[[\fP command, this performs pattern matching as -described above (\fBCompound Commands\fP). -.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. -.TP -\fIstring1\fP \fB>\fP \fIstring2\fP -True if \fIstring1\fP sorts after \fIstring2\fP lexicographically. -.TP -.I \fIarg1\fP \fBOP\fP \fIarg2\fP -.SM -.B OP -is one of -.BR \-eq , -.BR \-ne , -.BR \-lt , -.BR \-le , -.BR \-gt , -or -.BR \-ge . -These arithmetic binary operators return true if \fIarg1\fP -is equal to, not equal to, less than, less than or equal to, -greater than, or greater than or equal to \fIarg2\fP, respectively. -.I Arg1 -and -.I arg2 -may be positive or negative integers. -.PD -.SH "SIMPLE COMMAND EXPANSION" -When a simple command is executed, the shell performs the following -expansions, assignments, and redirections, from left to right. -.IP 1. -The words that the parser has marked as variable assignments (those -preceding the command name) and redirections are saved for later -processing. -.IP 2. -The words that are not variable assignments or redirections are -expanded. If any words remain after expansion, the first word -is taken to be the name of the command and the remaining words are -the arguments. -.IP 3. -Redirections are performed as described above under -.SM -.BR REDIRECTION . -.IP 4. -The text after the \fB=\fP in each variable assignment undergoes tilde -expansion, parameter expansion, command substitution, arithmetic expansion, -and quote removal before being assigned to the variable. -.PP -If no command name results, the variable assignments affect the current -shell environment. Otherwise, the variables are added to the environment -of the executed command and do not affect the current shell environment. -If any of the assignments attempts to assign a value to a readonly variable, -an error occurs, and the command exits with a non-zero status. -.PP -If no command name results, redirections are performed, but do not -affect the current shell environment. A redirection error causes the -command to exit with a non-zero status. -.PP -If there is a command name left after expansion, execution proceeds as -described below. Otherwise, the command exits. If one of the expansions -contained a command substitution, the exit status of the command is -the exit status of the last command substitution performed. If there -were no command substitutions, the command exits with a status of zero. -.SH "COMMAND EXECUTION" -After a command has been split into words, if it results in a -simple command and an optional list of arguments, the following -actions are taken. -.PP -If the command name contains no slashes, the shell attempts to -locate it. If there exists a shell function by that name, that -function is invoked as described above in -.SM -.BR FUNCTIONS . -If the name does not match a function, the shell searches for -it in the list of shell builtins. If a match is found, that -builtin is invoked. -.PP -If the name is neither a shell function nor a builtin, -and contains no slashes, -.B bash -searches each element of the -.SM -.B PATH -for a directory containing an executable file by that name. -.B Bash -uses a hash table to remember the full pathnames of executable -files (see -.B hash -under -.SM -.B "SHELL BUILTIN COMMANDS" -below). -A full search of the directories in -.SM -.B PATH -is performed only if the command is not found in the hash table. -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 -one or more slashes, the shell executes the named program in a -separate execution environment. -Argument 0 is set to the name given, and the remaining arguments -to the command are set to the arguments given, if any. -.PP -If this execution fails because the file is not in executable -format, and the file is not a directory, it is assumed to be -a \fIshell script\fP, a file -containing shell commands. A subshell is spawned to execute -it. This subshell reinitializes itself, so -that the effect is as if a new shell had been invoked -to handle the script, with the exception that the locations of -commands remembered by the parent (see -.B hash -below under -.SM -\fBSHELL BUILTIN COMMANDS\fP) -are retained by the child. -.PP -If the program is a file beginning with -.BR #! , -the remainder of the first line specifies an interpreter -for the program. The shell executes the -specified interpreter on operating systems that do not -handle this executable format themselves. The arguments to the -interpreter consist of a single optional argument following the -interpreter name on the first line of the program, followed -by the name of the program, followed by the command -arguments, if any. -.SH COMMAND EXECUTION ENVIRONMENT -The shell has an \fIexecution environment\fP, which consists of the -following: -.IP \(bu -open files inherited by the shell at invocation, as modified by -redirections supplied to the \fBexec\fP builtin -.IP \(bu -the current working directory as set by \fBcd\fP, \fBpushd\fP, or -\fBpopd\fP, or inherited by the shell at invocation -.IP \(bu -the file creation mode mask as set by \fBumask\fP or inherited from -the shell's parent -.IP \(bu -current traps set by \fBtrap\fP -.IP \(bu -shell parameters that are set by variable assignment or with \fBset\fP -or inherited from the shell's parent in the environment -.IP \(bu -shell functions defined during execution or inherited from the shell's -parent in the environment -.IP \(bu -options enabled at invocation (either by default or with command-line -arguments) or by \fBset\fP -.IP \(bu -options enabled by \fBshopt\fP -.IP \(bu -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 -.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. -.if n .sp 1 -.IP \(bu -the shell's open files, plus any modifications and additions specified -by redirections to the command -.IP \(bu -the current working directory -.IP \(bu -the file creation mode mask -.IP \(bu -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 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, 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 \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. -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 -.IR environment . -This is a list of -\fIname\fP\-\fIvalue\fP pairs, of the form -.IR "name\fR=\fPvalue" . -.PP -The shell provides several ways to manipulate the environment. -On invocation, the shell scans its own environment and -creates a parameter for each name found, automatically marking -it for -.I export -to child processes. Executed commands inherit the environment. -The -.B export -and -.B declare \-x -commands allow parameters and functions to be added to and -deleted from the environment. If the value of a parameter -in the environment is modified, the new value becomes part -of the environment, replacing the old. The environment -inherited by any executed command consists of the shell's -initial environment, whose values may be modified in the shell, -less any pairs removed by the -.B unset -command, plus any additions via the -.B export -and -.B declare \-x -commands. -.PP -The environment for any -.I simple command -or function may be augmented temporarily by prefixing it with -parameter assignments, as described above in -.SM -.BR PARAMETERS . -These assignment statements affect only the environment seen -by that command. -.PP -If the -.B \-k -option is set (see the -.B set -builtin command below), then -.I all -parameter assignments are placed in the environment for a command, -not just those that precede the command name. -.PP -When -.B bash -invokes an external command, the variable -.B _ -is set to the full filename of the command and passed to that -command in its environment. -.SH "EXIT STATUS" -.PP -The exit status of an executed command is the value returned by the -\fIwaitpid\fP system call or equivalent function. Exit statuses -fall between 0 and 255, though, as explained below, the shell may -use values above 125 specially. Exit statuses from shell builtins and -compound commands are also limited to this range. Under certain -circumstances, the shell will use special values to indicate specific -failure modes. -.PP -For the shell's purposes, a command which exits with a -zero exit status has succeeded. An exit status of zero -indicates success. A non-zero exit status indicates failure. -When a command terminates on a fatal signal \fIN\fP, \fBbash\fP uses -the value of 128+\fIN\fP as the exit status. -.PP -If a command is not found, the child process created to -execute it returns a status of 127. If a command is found -but is not executable, the return status is 126. -.PP -If a command fails because of an error during expansion or redirection, -the exit status is greater than zero. -.PP -Shell builtin commands return a status of 0 (\fItrue\fP) if -successful, and non-zero (\fIfalse\fP) if an error occurs -while they execute. -All builtins return an exit status of 2 to indicate incorrect usage, -generally invalid options or missing arguments. -.PP -\fBBash\fP itself returns the exit status of the last command -executed, unless a syntax error occurs, in which case it exits -with a non-zero value. See also the \fBexit\fP builtin -command below. -.SH SIGNALS -When \fBbash\fP is interactive, in the absence of any traps, it ignores -.SM -.B SIGTERM -(so that \fBkill 0\fP does not kill an interactive shell), -and -.SM -.B SIGINT -is caught and handled (so that the \fBwait\fP builtin is interruptible). -In all cases, \fBbash\fP ignores -.SM -.BR SIGQUIT . -If job control is in effect, -.B bash -ignores -.SM -.BR SIGTTIN , -.SM -.BR SIGTTOU , -and -.SM -.BR SIGTSTP . -.PP -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 -.SM -.B SIGINT -and -.SM -.B SIGQUIT -in addition to these inherited handlers. -Commands run as a result of command substitution ignore the -keyboard-generated job control signals -.SM -.BR SIGTTIN , -.SM -.BR SIGTTOU , -and -.SM -.BR SIGTSTP . -.PP -The shell exits by default upon receipt of a -.SM -.BR SIGHUP . -Before exiting, an interactive shell resends the -.SM -.B SIGHUP -to all jobs, running or stopped. -Stopped jobs are sent -.SM -.B SIGCONT -to ensure that they receive the -.SM -.BR SIGHUP . -To prevent the shell from -sending the signal to a particular job, it should be removed from the -jobs table with the -.B disown -builtin (see -.SM -.B "SHELL BUILTIN COMMANDS" -below) or marked -to not receive -.SM -.B SIGHUP -using -.BR "disown \-h" . -.PP -If the -.B huponexit -shell option has been set with -.BR shopt , -.B bash -sends a -.SM -.B SIGHUP -to all jobs when an interactive login shell exits. -.PP -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 -greater than 128, immediately after which the trap is executed. -.SH "JOB CONTROL" -.I Job control -refers to the ability to selectively stop (\fIsuspend\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 operating system kernel's terminal driver and -.BR bash . -.PP -The shell associates a -.I job -with each pipeline. It keeps a table of currently executing -jobs, which may be listed with the -.B jobs -command. When -.B bash -starts a job asynchronously (in the -.IR background ), -it prints a line that looks like: -.RS -.PP -[1] 25647 -.RE -.PP -indicating that this job is job number 1 and that the process ID -of the last process in the pipeline associated with this job is 25647. -All of the processes in a single pipeline are members of the same job. -.B Bash -uses the -.I job -abstraction as the basis for job control. -.PP -To facilitate the implementation of the user interface to job -control, the operating system maintains the notion of a \fIcurrent terminal -process group ID\fP. Members of this process group (processes whose -process group ID is equal to the current terminal process group ID) -receive keyboard-generated signals such as -.SM -.BR SIGINT . -These processes are said to be in the -.IR foreground . -.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, 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 kernel's terminal driver, -which, unless caught, suspends the process. -.PP -If the operating system on which -.B bash -is running supports -job control, -.B bash -contains facilities to use it. -Typing the -.I suspend -character (typically -.BR ^Z , -Control-Z) while a process is running -causes that process to be stopped and returns control to -.BR bash . -Typing the -.I "delayed suspend" -character (typically -.BR ^Y , -Control-Y) causes the process to be stopped when it -attempts to read input from the terminal, and control to -be returned to -.BR bash . -The user may then manipulate the state of this job, using the -.B bg -command to continue it in the background, the -.B fg -command to continue it in the foreground, or -the -.B kill -command to kill it. A \fB^Z\fP takes effect immediately, -and has the additional side effect of causing pending output -and typeahead to be discarded. -.PP -There are a number of ways to refer to a job in the shell. -The character -.B % -introduces a job specification (\fIjobspec\fP). Job number -.I n -may be referred to as -.BR %n . -A job may also be referred to using a prefix of the name used to -start it, or using a substring that appears in its command line. -For example, -.B %ce -refers to a stopped -.B ce -job. If a prefix matches more than one job, -.B bash -reports an error. Using -.BR %?ce , -on the other hand, refers to any job containing the string -.B ce -in its command line. If the substring matches more than one job, -.B bash -reports an error. The symbols -.B %% -and -.B %+ -refer to the shell's notion of the -.IR "current job" , -which is the last job stopped while it was in -the foreground or started in the background. -The -.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: -.B %1 -is a synonym for -\fB``fg %1''\fP, -bringing job 1 from the background into the foreground. -Similarly, -.B ``%1 &'' -resumes job 1 in the background, equivalent to -\fB``bg %1''\fP. -.PP -The shell learns immediately whenever a job changes state. -Normally, -.B bash -waits until it is about to print a prompt before reporting -changes in a job's status so as to not interrupt -any other output. If the -.B \-b -option to the -.B set -builtin command -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 (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. -If a second attempt to exit is made without an intervening command, -the shell does not print another warning, and any stopped -jobs are terminated. -.SH PROMPTING -When executing interactively, -.B bash -displays the primary prompt -.SM -.B PS1 -when it is ready to read a command, and the secondary prompt -.SM -.B PS2 -when it needs more input to complete a command. -.B Bash -allows these prompt strings to be customized by inserting a number of -backslash-escaped special characters that are decoded as follows: -.RS -.PD 0 -.TP -.B \ea -an ASCII bell character (07) -.TP -.B \ed -the date in "Weekday Month Date" format (e.g., "Tue May 26") -.TP -.B \eD{\fIformat\fP} -the \fIformat\fP is passed to \fIstrftime\fP(3) and the result is inserted -into the prompt string; an empty \fIformat\fP results in a locale-specific -time representation. The braces are required -.TP -.B \ee -an ASCII escape character (033) -.TP -.B \eh -the hostname up to the first `.' -.TP -.B \eH -the hostname -.TP -.B \ej -the number of jobs currently managed by the shell -.TP -.B \el -the basename of the shell's terminal device name -.TP -.B \en -newline -.TP -.B \er -carriage return -.TP -.B \es -the name of the shell, the basename of -.B $0 -(the portion following the final slash) -.TP -.B \et -the current time in 24-hour HH:MM:SS format -.TP -.B \eT -the current time in 12-hour HH:MM:SS format -.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 -.B \ev -the version of \fBbash\fP (e.g., 2.00) -.TP -.B \eV -the release of \fBbash\fP, version + patch level (e.g., 2.00.0) -.TP -.B \ew -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 -.SM -.B $HOME -abbreviated with a tilde -.TP -.B \e! -the history number of this command -.TP -.B \e# -the command number of this command -.TP -.B \e$ -if the effective UID is 0, a -.BR # , -otherwise a -.B $ -.TP -.B \e\fInnn\fP -the character corresponding to the octal number \fInnn\fP -.TP -.B \e\e -a backslash -.TP -.B \e[ -begin a sequence of non-printing characters, which could be used to -embed a terminal control sequence into the prompt -.TP -.B \e] -end a sequence of non-printing characters -.PD -.RE -.PP -The command number and the history number are usually different: -the history number of a command is its position in the history -list, which may include commands restored from the history file -(see -.SM -.B HISTORY -below), while the command number is the position in the sequence -of commands executed during the current shell session. -After the string is decoded, it is expanded via -parameter expansion, command substitution, arithmetic -expansion, and quote removal, subject to the value of the -.B promptvars -shell option (see the description of the -.B shopt -command under -.SM -.B "SHELL BUILTIN COMMANDS" -below). -.SH READLINE -This is the library that handles reading input when using an interactive -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. -Line editing can be enabled at any time using the -.B \-o emacs -or -.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 -keystrokes. Control keys are denoted by C\-\fIkey\fR, e.g., C\-n -means Control\-N. Similarly, -.I meta -keys are denoted by M\-\fIkey\fR, so M\-x means Meta\-X. (On keyboards -without a -.I meta -key, M\-\fIx\fP means ESC \fIx\fP, i.e., press the Escape key -then the -.I x -key. This makes ESC the \fImeta prefix\fP. -The combination M\-C\-\fIx\fP means ESC\-Control\-\fIx\fP, -or press the Escape key -then hold the Control key while pressing the -.I x -key.) -.PP -Readline commands may be given numeric -.IR arguments , -which normally act as a repeat count. -Sometimes, however, it is the sign of the argument that is significant. -Passing a negative argument to a command that acts in the forward -direction (e.g., \fBkill\-line\fP) causes that command to act in a -backward direction. -Commands whose behavior with arguments deviates from this are noted -below. -.PP -When a command is described as \fIkilling\fP text, the text -deleted is saved for possible future retrieval -(\fIyanking\fP). The killed text is saved in a -\fIkill ring\fP. Consecutive kills cause the text to be -accumulated into one unit, which can be yanked all at once. -Commands which do not kill text separate the chunks of text -on the kill ring. -.SS "Readline Initialization" -.PP -Readline is customized by putting commands in an initialization -file (the \fIinputrc\fP file). -The name of this file is taken from the value of the -.SM -.B INPUTRC -variable. If that variable is unset, the default is -.IR ~/.inputrc . -When a program which uses the readline library starts up, the -initialization file is read, and the key bindings and variables -are set. -There are only a few basic constructs allowed in the -readline initialization file. -Blank lines are ignored. -Lines beginning with a \fB#\fP are comments. -Lines beginning with a \fB$\fP indicate conditional constructs. -Other lines denote key bindings and variable settings. -.PP -The default key-bindings may be changed with an -.I inputrc -file. -Other programs that use this library may add their own commands -and bindings. -.PP -For example, placing -.RS -.PP -M\-Control\-u: universal\-argument -.RE -or -.RS -C\-Meta\-u: universal\-argument -.RE -into the -.I inputrc -would make M\-C\-u execute the readline command -.IR universal\-argument . -.PP -The following symbolic character names are recognized: -.IR RUBOUT , -.IR DEL , -.IR ESC , -.IR LFD , -.IR NEWLINE , -.IR RET , -.IR RETURN , -.IR SPC , -.IR SPACE , -and -.IR TAB . -.PP -In addition to command names, readline allows keys to be bound -to a string that is inserted when the key is pressed (a \fImacro\fP). -.SS "Readline Key Bindings" -.PP -The syntax for controlling key bindings in the -.I inputrc -file is simple. All that is required is the name of the -command or the text of a macro and a key sequence to which -it should be bound. The name may be specified in one of two ways: -as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP -prefixes, or as a key sequence. -.PP -When using the form \fBkeyname\fP:\^\fIfunction\-name\fP or \fImacro\fP, -.I keyname -is the name of a key spelled out in English. For example: -.sp -.RS -Control-u: universal\-argument -.br -Meta-Rubout: backward-kill-word -.br -Control-o: "> output" -.RE -.LP -In the above example, -.I C\-u -is bound to the function -.BR universal\-argument , -.I M\-DEL -is bound to the function -.BR backward\-kill\-word , -and -.I C\-o -is bound to run the macro -expressed on the right hand side (that is, to insert the text -.if t \f(CW> output\fP -.if n ``> output'' -into the line). -.PP -In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP, -.B keyseq -differs from -.B keyname -above in that strings denoting -an entire key sequence may be specified by placing the sequence -within double quotes. Some GNU Emacs style key escapes can be -used, as in the following example, but the symbolic character names -are not recognized. -.sp -.RS -"\eC\-u": universal\-argument -.br -"\eC\-x\eC\-r": re\-read\-init\-file -.br -"\ee[11~": "Function Key 1" -.RE -.PP -In this example, -.I C\-u -is again bound to the function -.BR universal\-argument . -.I "C\-x C\-r" -is bound to the function -.BR re\-read\-init\-file , -and -.I "ESC [ 1 1 ~" -is bound to insert the text -.if t \f(CWFunction Key 1\fP. -.if n ``Function Key 1''. -.PP -The full set of GNU Emacs style escape sequences is -.RS -.PD 0 -.TP -.B \eC\- -control prefix -.TP -.B \eM\- -meta prefix -.TP -.B \ee -an escape character -.TP -.B \e\e -backslash -.TP -.B \e" -literal " -.TP -.B \e\(aq -literal \(aq -.RE -.PD -.PP -In addition to the GNU Emacs style escape sequences, a second -set of backslash escapes is available: -.RS -.PD 0 -.TP -.B \ea -alert (bell) -.TP -.B \eb -backspace -.TP -.B \ed -delete -.TP -.B \ef -form feed -.TP -.B \en -newline -.TP -.B \er -carriage return -.TP -.B \et -horizontal tab -.TP -.B \ev -vertical tab -.TP -.B \e\fInnn\fP -the eight-bit character whose value is the octal value \fInnn\fP -(one to three digits) -.TP -.B \ex\fIHH\fP -the eight-bit character whose value is the hexadecimal value \fIHH\fP -(one or two hex digits) -.RE -.PD -.PP -When entering the text of a macro, single or double quotes must -be used to indicate a macro definition. -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 \(aq. -.PP -.B Bash -allows the current readline key bindings to be displayed or modified -with the -.B bind -builtin command. The editing mode may be switched during interactive -use by using the -.B \-o -option to the -.B set -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). -.SS "Readline Variables" -.PP -Readline has variables that can be used to further customize its -behavior. A variable may be set in the -.I inputrc -file with a statement of the form -.RS -.PP -\fBset\fP \fIvariable\-name\fP \fIvalue\fP -.RE -.PP -Except where noted, readline variables can take the values -.B On -or -.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 -.TP -.B bell\-style (audible) -Controls what happens when readline wants to ring the terminal bell. -If set to \fBnone\fP, readline never rings the bell. If set to -\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 colored\-stats (Off) -If set to \fBOn\fP, readline displays possible completions using different -colors to indicate their file type. -The color definitions are taken from the value of the \fBLS_COLORS\fP -environment variable. -.TP -.B comment\-begin (``#'') -The string that is inserted when the readline -.B insert\-comment -command is executed. -This command is bound to -.B M\-# -in emacs mode and to -.B # -in vi command mode. -.TP -.B completion\-ignore\-case (Off) -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 -generated by the \fBpossible\-completions\fP command. -It may be set to any integer value greater than or equal to -zero. If the number of possible completions is greater than -or equal to the value of this variable, the user is asked whether -or not he wishes to view them; otherwise they are simply listed -on the terminal. -.TP -.B convert\-meta (On) -If set to \fBOn\fP, readline will convert characters with the -eighth bit set to an ASCII key sequence -by stripping the eighth bit and prefixing an -escape character (in effect, using escape as the \fImeta prefix\fP). -.TP -.B disable\-completion (Off) -If set to \fBOn\fP, readline will inhibit word completion. Completion -characters will be inserted into the line as if they had been -mapped to \fBself-insert\fP. -.TP -.B editing\-mode (emacs) -Controls whether readline begins with a set of key bindings similar -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 -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, any existing history entries are deleted and no new entries -are saved. -If set to a value less than zero, the number of history entries is not -limited. -By default, the number of history entries 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 -becomes longer than the screen width rather than wrapping to a new line. -.TP -.B input\-meta (Off) -If set to \fBOn\fP, readline will enable eight-bit input (that is, -it will not strip the high bit from the characters it reads), -regardless of what the terminal claims it can support. The name -.B meta\-flag -is a synonym for this variable. -.TP -.B isearch\-terminators (``C\-[C\-J'') -The string of characters that should terminate an incremental -search without subsequently executing the character as a command. -If this variable has not been given a value, the characters -\fIESC\fP and \fIC\-J\fP will terminate an incremental search. -.TP -.B keymap (emacs) -Set the current readline keymap. The set of valid keymap names is -\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, -vi\-command\fP, and -.IR vi\-insert . -\fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is -equivalent to \fIemacs\-standard\fP. The default value is -.IR emacs ; -the value of -.B editing\-mode -also affects the default keymap. -.TP -.B keyseq\-timeout (500) -Specifies the duration \fIreadline\fP will wait for a character when reading an -ambiguous key sequence (one that can form a complete key sequence using -the input read so far, or can take additional input to complete a longer -key sequence). -If no input is received within the timeout, \fIreadline\fP will use the shorter -but complete key sequence. -The value is specified in milliseconds, so a value of 1000 means that -\fIreadline\fP will wait one second for additional input. -If this variable is set to a value less than or equal to zero, or to a -non-numeric value, \fIreadline\fP will wait until another key is pressed to -decide which key sequence to complete. -.TP -.B mark\-directories (On) -If set to \fBOn\fP, completed directory names have a slash -appended. -.TP -.B mark\-modified\-lines (Off) -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. -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 -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 -set to -.BR On , -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 show\-mode\-in\-prompt (Off) -If set to \fBOn\fP, add a character to the beginning of the prompt -indicating the editing mode: emacs (@), vi command (:) or vi -insertion (+). -.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 -completions. -.PD -.SS "Readline Conditional Constructs" -.PP -Readline implements a facility similar in spirit to the conditional -compilation features of the C preprocessor which allows key -bindings and variable settings to be performed as the result -of tests. There are four parser directives used. -.IP \fB$if\fP -The -.B $if -construct allows bindings to be made based on the -editing mode, the terminal being used, or the application using -readline. The text of the test extends to the end of the line; -no characters are required to isolate it. -.RS -.IP \fBmode\fP -The \fBmode=\fP form of the \fB$if\fP directive is used to test -whether readline is in emacs or vi mode. -This may be used in conjunction -with the \fBset keymap\fP command, for instance, to set bindings in -the \fIemacs\-standard\fP and \fIemacs\-ctlx\fP keymaps only if -readline is starting out in emacs mode. -.IP \fBterm\fP -The \fBterm=\fP form may be used to include terminal-specific -key bindings, perhaps to bind the key sequences output by the -terminal's function keys. The word on the right side of the -.B = -is tested against the both full name of the terminal and the portion -of the terminal name before the first \fB\-\fP. This allows -.I sun -to match both -.I sun -and -.IR sun\-cmd , -for instance. -.IP \fBapplication\fP -The \fBapplication\fP construct is used to include -application-specific settings. Each program using the readline -library sets the \fIapplication name\fP, and an initialization -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 \fBbash\fP: -.sp 1 -.RS -.nf -\fB$if\fP Bash -# Quote the current or previous word -"\eC\-xq": "\eeb\e"\eef\e"" -\fB$endif\fP -.fi -.RE -.RE -.IP \fB$endif\fP -This command, as seen in the previous example, terminates an -\fB$if\fP command. -.IP \fB$else\fP -Commands in this branch of the \fB$if\fP directive are executed if -the test fails. -.IP \fB$include\fP -This directive takes a single filename as an argument and reads commands -and bindings from that file. For example, the following directive -would read \fI/etc/inputrc\fP: -.sp 1 -.RS -.nf -\fB$include\fP \^ \fI/etc/inputrc\fP -.fi -.RE -.SS Searching -.PP -Readline provides commands for searching through the command history -(see -.SM -.B HISTORY -below) for lines containing a specified string. -There are two search modes: -.I incremental -and -.IR non-incremental . -.PP -Incremental searches begin before the user has finished typing the -search string. -As each character of the search string is typed, readline displays -the next entry from the history matching the string typed so far. -An incremental search requires only as many characters as needed to -find the desired history entry. -The characters present in the value of the \fBisearch-terminators\fP -variable are used to terminate an incremental search. -If that variable has not been assigned a value the Escape and -Control-J characters will terminate an incremental search. -Control-G will abort an incremental search and restore the original -line. -When the search is terminated, the history entry containing the -search string becomes the current line. -.PP -To find other matching entries in the history list, type Control-S or -Control-R as appropriate. -This will search backward or forward in the history for the next -entry matching the search string typed so far. -Any other key sequence bound to a readline command will terminate -the search and execute that command. -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. -.SS "Readline Command Names" -.PP -The following is a list of the names of the commands and the default -key sequences to which they are bound. -Command names without an accompanying key sequence are unbound by default. -In the following descriptions, \fIpoint\fP refers to the current cursor -position, and \fImark\fP refers to a cursor position saved by the -\fBset\-mark\fP command. -The text between the point and mark is referred to as the \fIregion\fP. -.SS Commands for Moving -.PP -.PD 0 -.TP -.B beginning\-of\-line (C\-a) -Move to the start of the current line. -.TP -.B end\-of\-line (C\-e) -Move to the end of the line. -.TP -.B forward\-char (C\-f) -Move forward a character. -.TP -.B backward\-char (C\-b) -Move back a character. -.TP -.B forward\-word (M\-f) -Move forward to the end of the next word. Words are composed of -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). -.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. -With an argument, refresh the current line without clearing the -screen. -.TP -.B redraw\-current\-line -Refresh the current line. -.PD -.SS Commands for Manipulating the History -.PP -.PD 0 -.TP -.B accept\-line (Newline, Return) -Accept the line regardless of where the cursor is. If this line is -non-empty, add it to the history list according to the state of the -.SM -.B HISTCONTROL -variable. If the line is a modified history -line, then restore the history line to its original state. -.TP -.B previous\-history (C\-p) -Fetch the previous command from the history list, moving back in -the list. -.TP -.B next\-history (C\-n) -Fetch the next command from the history list, moving forward in the -list. -.TP -.B beginning\-of\-history (M\-<) -Move to the first line in the history. -.TP -.B end\-of\-history (M\->) -Move to the end of the input history, i.e., the line currently being -entered. -.TP -.B reverse\-search\-history (C\-r) -Search backward starting at the current line and moving `up' through -the history as necessary. This is an incremental search. -.TP -.B forward\-search\-history (C\-s) -Search forward starting at the current line and moving `down' through -the history as necessary. This is an incremental search. -.TP -.B non\-incremental\-reverse\-search\-history (M\-p) -Search backward through the history starting at the current line -using a non-incremental search for a string supplied by the user. -.TP -.B non\-incremental\-forward\-search\-history (M\-n) -Search forward through the history using a non-incremental search for -a string supplied by the user. -.TP -.B history\-search\-forward -Search forward through the history for the string of characters -between the start of the current line and the point. -This is a non-incremental search. -.TP -.B history\-search\-backward -Search backward through the history for the string of characters -between the start of the current line and the point. -This is a non-incremental search. -.TP -.B yank\-nth\-arg (M\-C\-y) -Insert the first argument to the previous command (usually -the second word on the previous line) at point. -With an argument -.IR n , -insert the \fIn\fPth word from the previous command (the words -in the previous command begin with word 0). A negative argument -inserts the \fIn\fPth word from the end of the previous command. -Once the argument \fIn\fP is computed, the argument is extracted -as if the "!\fIn\fP" history expansion had been specified. -.TP -.B -yank\-last\-arg (M\-.\^, M\-_\^) -Insert the last argument to the previous command (the last word of -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 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 word, -as if the "!$" history expansion had been specified. -.TP -.B shell\-expand\-line (M\-C\-e) -Expand the line as the shell does. This -performs alias and history expansion as well as all of the shell -word expansions. See -.SM -.B HISTORY EXPANSION -below for a description of history expansion. -.TP -.B history\-expand\-line (M\-^) -Perform history expansion on the current line. -See -.SM -.B HISTORY EXPANSION -below for a description of history expansion. -.TP -.B magic\-space -Perform history expansion on the current line and insert a space. -See -.SM -.B HISTORY EXPANSION -below for a description of history expansion. -.TP -.B alias\-expand\-line -Perform alias expansion on the current line. -See -.SM -.B ALIASES -above for a description of alias expansion. -.TP -.B history\-and\-alias\-expand\-line -Perform history and alias expansion on the current line. -.TP -.B insert\-last\-argument (M\-.\^, M\-_\^) -A synonym for \fByank\-last\-arg\fP. -.TP -.B operate\-and\-get\-next (C\-o) -Accept the current line for execution and fetch the next line -relative to the current line from the history for editing. Any -argument is ignored. -.TP -.B edit\-and\-execute\-command (C\-xC\-e) -Invoke an editor on the current command line, and execute the result as shell -commands. -\fBBash\fP attempts to invoke -.SM -.BR $VISUAL , -.SM -.BR $EDITOR , -and \fIemacs\fP as the editor, in that order. -.PD -.SS Commands for Changing Text -.PP -.PD 0 -.TP -.B \fIend\-of\-file\fP (usually C\-d) -The character indicating end-of-file as set, for example, by -.if t \f(CWstty\fP. -.if n ``stty''. -If this character is read when there are no characters -on the line, and point is at the beginning of the line, Readline -interprets it as the end of input and returns -.SM -.BR EOF . -.TP -.B delete\-char (C\-d) -Delete the character at point. -If this function is bound to the -same character as the tty \fBEOF\fP character, as \fBC\-d\fP -commonly is, see above for the effects. -.TP -.B backward\-delete\-char (Rubout) -Delete the character behind the cursor. When given a numeric argument, -save the deleted text on the kill ring. -.TP -.B forward\-backward\-delete\-char -Delete the character under the cursor, unless the cursor is at the -end of the line, in which case the character behind the cursor is -deleted. -.TP -.B quoted\-insert (C\-q, C\-v) -Add the next character typed to the line verbatim. This is -how to insert characters like \fBC\-q\fP, for example. -.TP -.B tab\-insert (C\-v TAB) -Insert a tab character. -.TP -.B self\-insert (a,\ b,\ A,\ 1,\ !,\ ...) -Insert the character typed. -.TP -.B transpose\-chars (C\-t) -Drag the character before point forward over the character at point, -moving point forward as well. -If point is at the end of the line, then this transposes -the two characters before point. -Negative arguments have no effect. -.TP -.B transpose\-words (M\-t) -Drag the word 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, -uppercase the previous word, but do not move point. -.TP -.B downcase\-word (M\-l) -Lowercase the current (or following) word. With a negative argument, -lowercase the previous word, but do not move point. -.TP -.B capitalize\-word (M\-c) -Capitalize the current (or following) word. With a negative argument, -capitalize the previous word, but do not move point. -.TP -.B overwrite\-mode -Toggle overwrite mode. With an explicit positive numeric argument, -switches to overwrite mode. With an explicit non-positive numeric -argument, switches to insert mode. This command affects only -\fBemacs\fP mode; \fBvi\fP mode does overwrite differently. -Each call to \fIreadline()\fP starts in insert mode. -In overwrite mode, characters bound to \fBself\-insert\fP replace -the text at point rather than pushing the text to the right. -Characters bound to \fBbackward\-delete\-char\fP replace the character -before point with a space. By default, this command is unbound. -.PD -.SS Killing and Yanking -.PP -.PD 0 -.TP -.B kill\-line (C\-k) -Kill the text from point to the end of the line. -.TP -.B backward\-kill\-line (C\-x Rubout) -Kill backward to the beginning of the line. -.TP -.B unix\-line\-discard (C\-u) -Kill backward from point to the beginning of the line. -The killed text is saved on the kill-ring. -.\" There is no real difference between this and backward-kill-line -.TP -.B kill\-whole\-line -Kill all characters on the current line, no matter where point is. -.TP -.B 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 \fBforward\-word\fP. -.TP -.B backward\-kill\-word (M\-Rubout) -Kill the word behind point. -Word boundaries are the same as those used by \fBbackward\-word\fP. -.TP -.B shell\-kill\-word -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 -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 -.B kill\-region -Kill the text in the current region. -.TP -.B copy\-region\-as\-kill -Copy the text in the region to the kill buffer. -.TP -.B copy\-backward\-word -Copy the word before point to the kill buffer. -The word boundaries are the same as \fBbackward\-word\fP. -.TP -.B copy\-forward\-word -Copy the word following point to the kill buffer. -The word boundaries are the same as \fBforward\-word\fP. -.TP -.B yank (C\-y) -Yank the top of the kill ring into the buffer at point. -.TP -.B yank\-pop (M\-y) -Rotate the kill ring, and yank the new top. Only works following -.B yank -or -.BR yank\-pop . -.PD -.SS Numeric Arguments -.PP -.PD 0 -.TP -.B digit\-argument (M\-0, M\-1, ..., M\-\-) -Add this digit to the argument already accumulating, or start a new -argument. M\-\- starts a negative argument. -.TP -.B universal\-argument -This is another way to specify an argument. -If this command is followed by one or more digits, optionally with a -leading minus sign, those digits define the argument. -If the command is followed by digits, executing -.B universal\-argument -again ends the numeric argument, but is otherwise ignored. -As a special case, if this command is immediately followed by a -character that is neither a digit or minus sign, the argument count -for the next command is multiplied by four. -The argument count is initially one, so executing this function the -first time makes the argument count four, a second time makes the -argument count sixteen, and so on. -.PD -.SS Completing -.PP -.PD 0 -.TP -.B complete (TAB) -Attempt to perform completion on the text before point. -.B Bash -attempts completion treating the text as a variable (if the -text begins with \fB$\fP), username (if the text begins with -\fB~\fP), hostname (if the text begins with \fB@\fP), or -command (including aliases and functions) in turn. If none -of these produces a match, filename completion is attempted. -.TP -.B possible\-completions (M\-?) -List the possible completions of the text before point. -.TP -.B insert\-completions (M\-*) -Insert all completions of the text before point -that would have been generated by -\fBpossible\-completions\fP. -.TP -.B menu\-complete -Similar to \fBcomplete\fP, but replaces the word to be completed -with a single match from the list of possible completions. -Repeated execution of \fBmenu\-complete\fP steps through the list -of possible completions, inserting each match in turn. -At the end of the list of completions, the bell is rung -(subject to the setting of \fBbell\-style\fP) -and the original text is restored. -An argument of \fIn\fP moves \fIn\fP positions forward in the list -of matches; a negative argument may be used to move backward -through the list. -This command is intended to be bound to \fBTAB\fP, but is unbound -by default. -.TP -.B 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). -If at the end of the line, behaves identically to -\fBpossible\-completions\fP. -This command is unbound by default. -.TP -.B complete\-filename (M\-/) -Attempt filename completion on the text before point. -.TP -.B possible\-filename\-completions (C\-x /) -List the possible completions of the text before point, -treating it as a filename. -.TP -.B complete\-username (M\-~) -Attempt completion on the text before point, treating -it as a username. -.TP -.B possible\-username\-completions (C\-x ~) -List the possible completions of the text before point, -treating it as a username. -.TP -.B complete\-variable (M\-$) -Attempt completion on the text before point, treating -it as a shell variable. -.TP -.B possible\-variable\-completions (C\-x $) -List the possible completions of the text before point, -treating it as a shell variable. -.TP -.B complete\-hostname (M\-@) -Attempt completion on the text before point, treating -it as a hostname. -.TP -.B possible\-hostname\-completions (C\-x @) -List the possible completions of the text before point, -treating it as a hostname. -.TP -.B complete\-command (M\-!) -Attempt completion on the text before point, treating -it as a command name. Command completion attempts to -match the text against aliases, reserved words, shell -functions, shell builtins, and finally executable filenames, -in that order. -.TP -.B possible\-command\-completions (C\-x !) -List the possible completions of the text before point, -treating it as a command name. -.TP -.B dynamic\-complete\-history (M\-TAB) -Attempt completion on the text before point, comparing -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 -.B Brace Expansion -above). -.PD -.SS Keyboard Macros -.PP -.PD 0 -.TP -.B start\-kbd\-macro (C\-x (\^) -Begin saving the characters typed into the current keyboard macro. -.TP -.B end\-kbd\-macro (C\-x )\^) -Stop saving the characters typed into the current keyboard macro -and store the definition. -.TP -.B call\-last\-kbd\-macro (C\-x e) -Re-execute the last keyboard macro defined, by making the characters -in the macro appear as if typed at the keyboard. -.TP -.B print\-last\-kbd\-macro () -Print the last keyboard macro defined in a format suitable for the -\fIinputrc\fP file. -.PD -.SS Miscellaneous -.PP -.PD 0 -.TP -.B re\-read\-init\-file (C\-x C\-r) -Read in the contents of the \fIinputrc\fP file, and incorporate -any bindings or variable assignments found there. -.TP -.B abort (C\-g) -Abort the current editing command and -ring the terminal's bell (subject to the setting of -.BR bell\-style ). -.TP -.B do\-uppercase\-version (M\-a, M\-b, M\-\fIx\fP, ...) -If the metafied character \fIx\fP is lowercase, run the command -that is bound to the corresponding uppercase character. -.TP -.B prefix\-meta (ESC) -Metafy the next character typed. -.SM -.B ESC -.B f -is equivalent to -.BR Meta\-f . -.TP -.B undo (C\-_, C\-x C\-u) -Incremental undo, separately remembered for each line. -.TP -.B revert\-line (M\-r) -Undo all changes made to this line. This is like executing the -.B undo -command enough times to return the line to its initial state. -.TP -.B tilde\-expand (M\-&) -Perform tilde expansion on the current word. -.TP -.B set\-mark (C\-@, M\-<space>) -Set the mark to the point. If a -numeric argument is supplied, the mark is set to that position. -.TP -.B exchange\-point\-and\-mark (C\-x C\-x) -Swap the point with the mark. The current cursor position is set to -the saved position, and the old cursor position is saved as the mark. -.TP -.B character\-search (C\-]) -A character is read and point is moved to the next occurrence of that -character. A negative count searches for previous occurrences. -.TP -.B character\-search\-backward (M\-C\-]) -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 -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 filenames 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 filenames 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 -readline output stream. 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 -.B dump\-variables -Print all of the settable readline variables and their values to the -readline output stream. 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 -.B dump\-macros -Print all of the readline key sequences bound to macros and the -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 -.B display\-shell\-version (C\-x C\-v) -Display version information about the current instance of -.BR bash . -.PD -.SS Programmable Completion -.PP -When word completion is attempted for an argument to a command for -which a completion specification (a \fIcompspec\fP) has been defined -using the \fBcomplete\fP builtin (see -.SM -.B "SHELL BUILTIN COMMANDS" -below), the programmable completion facilities are invoked. -.PP -First, the command name is identified. -If 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. -If a compspec is not found, the default \fBbash\fP completion as -described above under \fBCompleting\fP is performed. -.PP -First, the actions specified by the compspec are used. -Only matches which are prefixed by the word being completed are -returned. -When the -.B \-f -or -.B \-d -option is used for filename or directory name completion, the shell -variable -.SM -.B FIGNORE -is used to filter the matches. -.PP -Any completions specified by a 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. -The -.SM -.B GLOBIGNORE -shell variable is not used to filter the matches, but the -.SM -.B FIGNORE -variable is used. -.PP -Next, the string specified as the argument to the \fB\-W\fP option -is considered. -The string is first split using the characters in the -.SM -.B IFS -special variable as delimiters. -Shell quoting is honored. -Each word is then expanded using -brace expansion, tilde expansion, parameter and variable expansion, -command substitution, and arithmetic expansion, -as described above under -.SM -.BR EXPANSION . -The results are split using the rules described above under -\fBWord Splitting\fP. -The results of the expansion are prefix-matched against the word being -completed, and the matching words become the possible completions. -.PP -After these matches have been generated, any shell function or command -specified with the \fB\-F\fP and \fB\-C\fP options is invoked. -When the command or function is invoked, the -.SM -.BR COMP_LINE , -.SM -.BR COMP_POINT , -.SM -.BR COMP_KEY , -and -.SM -.B COMP_TYPE -variables are assigned values as described above under -\fBShell Variables\fP. -If a shell function is being invoked, the -.SM -.B COMP_WORDS -and -.SM -.B COMP_CWORD -variables are also set. -When the function or command is invoked, -the first argument (\fB$1\fP) is the name of the command whose arguments are -being completed, -the second argument (\fB$2\fP) is the word being completed, -and the third argument (\fB$3\fP) is the word preceding the word being -completed on the current command line. -No filtering of the generated completions against the word being completed -is performed; the function or command has complete freedom in generating -the matches. -.PP -Any function specified with \fB\-F\fP is invoked first. -The function may use any of the shell facilities, including the -\fBcompgen\fP builtin described below, to generate the matches. -It must put the possible completions in the -.SM -.B COMPREPLY -array variable, one per array element. -.PP -Next, any command specified with the \fB\-C\fP option is invoked -in an environment equivalent to command substitution. -It should print a list of completions, one per line, to the -standard output. -Backslash may be used to escape a newline, if necessary. -.PP -After all of the possible completions are generated, any filter -specified with the \fB\-X\fP option is applied to the list. -The filter is a pattern as used for pathname expansion; a \fB&\fP -in the pattern is replaced with the text of the word being completed. -A literal \fB&\fP may be escaped with a backslash; the backslash -is removed before attempting a match. -Any completion that matches the pattern will be removed from the list. -A leading \fB!\fP negates the pattern; in this case any completion -not matching the pattern will be removed. -.PP -Finally, any prefix and suffix specified with the \fB\-P\fP and \fB\-S\fP -options are added to each member of the completion list, and the result is -returned to the readline completion code as the list of possible -completions. -.PP -If the previously-applied actions do not generate any matches, and the -\fB\-o dirnames\fP option was supplied to \fBcomplete\fP when the -compspec was defined, directory name completion is attempted. -.PP -If the \fB\-o plusdirs\fP option was supplied to \fBcomplete\fP when the -compspec was defined, directory name completion is attempted and any -matches are added to the results of the other actions. -.PP -By default, if a compspec is found, whatever it generates is returned -to the completion code as the full set of possible completions. -The default \fBbash\fP completions are not attempted, and the readline -default of filename completion is disabled. -If the \fB\-o bashdefault\fP option was supplied to \fBcomplete\fP when -the compspec was defined, the \fBbash\fP default completions are attempted -if the compspec generates no matches. -If the \fB\-o default\fP option was supplied to \fBcomplete\fP when the -compspec was defined, readline's default completion will be performed -if the compspec (and, if attempted, the default \fBbash\fP completions) -generate no matches. -.PP -When a compspec indicates that directory name completion is desired, -the programmable completion functions force readline to append a slash -to completed names which are symbolic links to directories, subject to -the value of the \fBmark\-directories\fP readline variable, regardless -of the setting of the \fBmark-symlinked\-directories\fP readline variable. -.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 -o bashdefault -o default -.br -\fP -.SH HISTORY -When the -.B \-o history -option to the -.B set -builtin is enabled, the shell provides access to the -\fIcommand history\fP, -the list of commands previously typed. -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 -.B HISTSIZE -commands (default 500) is saved. The shell -stores each command in the history list prior to parameter and -variable expansion (see -.SM -.B EXPANSION -above) but after history expansion is performed, subject to the -values of the shell variables -.SM -.B HISTIGNORE -and -.SM -.BR HISTCONTROL . -.PP -On startup, the history is initialized from the file named by -the variable -.SM -.B HISTFILE -(default \fI~/.bash_history\fP). -The file named by the value of -.SM -.B HISTFILE -is truncated, if necessary, to contain no more than -the number of lines specified by the value of -.SM -.BR HISTFILESIZE . -If \fBHISTFILESIZE\fP is unset, or set to null, a non-numeric value, -or a numeric value less than zero, the history file is not truncated. -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 a shell with history enabled exits, the last -.SM -.B $HISTSIZE -lines are copied from the history list to -.SM -.BR $HISTFILE . -If the -.B histappend -shell option is enabled -(see the description of -.B shopt -under -.SM -.B "SHELL BUILTIN COMMANDS" -below), the lines are appended to the history file, -otherwise the history file is overwritten. -If -.SM -.B HISTFILE -is unset, or if the history file is unwritable, the history is -not saved. -If the -.SM -.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. -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 -lines. If -.SM -.B HISTFILESIZE -is unset, or set to null, a non-numeric value, -or a numeric value less than zero, the history file is not truncated. -.PP -The builtin command -.B fc -(see -.SM -.B SHELL BUILTIN COMMANDS -below) may be used to list or edit and re-execute a portion of -the history list. -The -.B history -builtin may be used to display or modify the history list and -manipulate the history file. -When using command-line editing, search commands -are available in each editing mode that provide access to the -history list. -.PP -The shell allows control over which commands are saved on the history -list. The -.SM -.B HISTCONTROL -and -.SM -.B HISTIGNORE -variables may be set to cause the shell to save only a subset of the -commands entered. -The -.B cmdhist -shell option, if enabled, causes the shell to attempt to save each -line of a multi-line command in the same history entry, adding -semicolons where necessary to preserve syntactic correctness. -The -.B lithist -shell option causes the shell to save the command with embedded newlines -instead of semicolons. See the description of the -.B shopt -builtin below under -.SM -.B "SHELL BUILTIN COMMANDS" -for information on setting and unsetting shell options. -.SH "HISTORY EXPANSION" -.PP -The shell supports a history expansion feature that -is similar to the history expansion in -.BR csh. -This section describes what syntax features are available. This -feature is enabled by default for interactive shells, and can be -disabled using the -.B +H -option to the -.B set -builtin command (see -.SM -.B SHELL BUILTIN COMMANDS -below). Non-interactive shells do not perform history expansion -by default. -.PP -History expansions introduce words from the history list into -the input stream, making it easy to repeat commands, insert the -arguments to a previous command into the current input line, or -fix errors in previous commands quickly. -.PP -History expansion is performed immediately after a complete line -is read, before the shell breaks it into words. -It takes place in two parts. -The first is to determine which line from the history list -to use during substitution. -The second is to select portions of that line for inclusion into -the current one. -The line selected from the history is the \fIevent\fP, -and the portions of that line that are acted upon are \fIwords\fP. -Various \fImodifiers\fP are available to manipulate the selected words. -The line is broken into words in the same fashion as when reading input, -so that several \fImetacharacter\fP-separated words surrounded by -quotes are considered one word. -History expansions are introduced by the appearance of the -history expansion character, which is \^\fB!\fP\^ by default. -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. -If the -.B histverify -shell option is enabled (see the description of the -.B shopt -builtin below), and -.B readline -is being used, history substitutions are not immediately passed to -the shell parser. -Instead, the expanded line is reloaded into the -.B readline -editing buffer for further modification. -If -.B readline -is being used, and the -.B histreedit -shell option is enabled, a failed history substitution will be reloaded -into the -.B readline -editing buffer for correction. -The -.B \-p -option to the -.B history -builtin command may be used to see what a history expansion will -do before using it. -The -.B \-s -option to the -.B history -builtin may be used to add commands to the end of the history list -without actually executing them, so that they are available for -subsequent recall. -.PP -The shell allows control of the various characters used by the -history expansion mechanism (see the description of -.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 -history list. -Unless the reference is absolute, events are relative to the current -position in the history list. -.PP -.PD 0 -.TP -.B ! -Start a history substitution, except when followed by a -.BR blank , -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 -.IR n . -.TP -.B !\-\fIn\fR -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 preceding the current position in the -history list starting with -.IR string . -.TP -.B !?\fIstring\fR\fB[?]\fR -Refer to the most recent command preceding the current position 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 previous command, replacing -.I string1 -with -.IR string2 . -Equivalent to -``!!:s/\fIstring1\fP/\fIstring2\fP/'' -(see \fBModifiers\fP below). -.TP -.B !# -The entire command line typed so far. -.PD -.SS Word Designators -.PP -Word designators are used to select desired words from the event. -A -.B : -separates the event specification from the word designator. -It may be omitted if the word designator begins with a -.BR ^ , -.BR $ , -.BR * , -.BR \- , -or -.BR % . -Words are numbered from the beginning of the line, -with the first word being denoted by 0 (zero). -Words are inserted into the current line separated by single spaces. -.PP -.PD 0 -.TP -.B 0 (zero) -The zeroth word. For the shell, this is the command -word. -.TP -.I n -The \fIn\fRth word. -.TP -.B ^ -The first argument. That is, word 1. -.TP -.B $ -The last word. This is usually the last argument, but will expand to the -zeroth word if there is only one word in the line. -.TP -.B % -The word matched by the most recent `?\fIstring\fR?' search. -.TP -.I x\fB\-\fPy -A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'. -.TP -.B * -All of the words but the zeroth. This is a synonym -for `\fI1\-$\fP'. It is not an error to use -.B * -if there is just one -word in the event; the empty string is returned in that case. -.TP -.B x* -Abbreviates \fIx\-$\fP. -.TP -.B x\- -Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word. -.PD -.PP -If a word designator is supplied without an event specification, the -previous command is used as the event. -.SS Modifiers -.PP -After the optional word designator, there may appear a sequence of -one or more of the following modifiers, each preceded by a `:'. -.PP -.PD 0 -.PP -.TP -.B h -Remove a trailing filename component, leaving only the head. -.TP -.B t -Remove all leading filename components, leaving the tail. -.TP -.B r -Remove a trailing suffix of the form \fI.xxx\fP, leaving the -basename. -.TP -.B e -Remove all but the trailing suffix. -.TP -.B p -Print the new command but do not execute it. -.TP -.B q -Quote the substituted words, escaping further substitutions. -.TP -.B x -Quote the substituted words as with -.BR q , -but break into words at -.B blanks -and newlines. -.TP -.B s/\fIold\fP/\fInew\fP/ -Substitute -.I new -for the first occurrence of -.I old -in the event line. Any delimiter can be used in place of /. The -final delimiter is optional if it is the last character of the -event line. The delimiter may be quoted in -.I old -and -.I new -with a single backslash. If & appears in -.IR new , -it is replaced by -.IR old . -A single backslash will quote the &. If -.I old -is null, it is set to the last -.I old -substituted, or, if no previous history substitutions took place, -the last -.I string -in a -.B !?\fIstring\fR\fB[?]\fR -search. -.TP -.B & -Repeat the previous substitution. -.TP -.B g -Cause changes to be applied over the entire event line. This is -used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR') -or `\fB:&\fP'. If used with -`\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 -.zZ -.PP -Unless otherwise noted, each builtin command documented in this -section as accepting options preceded by -.B \- -accepts -.B \-\- -to signify the end of the 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 -\fB:\fP [\fIarguments\fP] -.PD -No effect; the command does nothing beyond expanding -.I arguments -and performing any specified -redirections. A zero exit code is returned. -.TP -\fB .\| \fP \fIfilename\fP [\fIarguments\fP] -.PD 0 -.TP -\fBsource\fP \fIfilename\fP [\fIarguments\fP] -.PD -Read and execute commands from -.I filename -in the current -shell environment and return the exit status of the last command -executed from -.IR filename . -If -.I filename -does not contain a slash, filenames in -.SM -.B PATH -are used to find the directory containing -.IR filename . -The file searched for in -.SM -.B PATH -need not be executable. -When \fBbash\fP is not in \fIposix mode\fP, the current directory is -searched if no file is found in -.SM -.BR PATH . -If the -.B sourcepath -option to the -.B shopt -builtin command is turned off, the -.SM -.B PATH -is not searched. -If any \fIarguments\fP are supplied, they become the positional -parameters when \fIfilename\fP is executed. Otherwise the positional -parameters are unchanged. -The return status is the status of the last command exited within -the script (0 if no commands are executed), and false if -.I filename -is not found or cannot be read. -.TP -\fBalias\fP [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] -\fBAlias\fP with no arguments or with the -.B \-p -option prints the list of aliases in the form -\fBalias\fP \fIname\fP=\fIvalue\fP on standard output. -When arguments are supplied, an alias is defined for -each \fIname\fP whose \fIvalue\fP is given. -A trailing space in \fIvalue\fP causes the next word to be -checked for alias substitution when the alias is expanded. -For each \fIname\fP in the argument list for which no \fIvalue\fP -is supplied, the name and value of the alias is printed. -\fBAlias\fP returns true unless a \fIname\fP is given for which -no alias has been defined. -.TP -\fBbg\fP [\fIjobspec\fP ...] -Resume each suspended job \fIjobspec\fP in the background, as if it -had been started with -.BR & . -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, any specified \fIjobspec\fP was not found -or was started without job control. -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-lpsvPSVX\fP] -.PD 0 -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] [\fB\-q\fP \fIfunction\fP] [\fB\-u\fP \fIfunction\fP] [\fB\-r\fP \fIkeyseq\fP] -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-f\fP \fIfilename\fP -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fB\-x\fP \fIkeyseq\fP:\fIshell\-command\fP -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIfunction\-name\fP -.TP -\fBbind\fP [\fB\-m\fP \fIkeymap\fP] \fIkeyseq\fP:\fIreadline\-command\fP -.PD -Display current -.B readline -key and function bindings, bind a key sequence to a -.B readline -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 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 \-m \fIkeymap\fP -Use -.I keymap -as the keymap to be affected by the subsequent bindings. -Acceptable -.I keymap -names are -\fIemacs, emacs\-standard, emacs\-meta, emacs\-ctlx, vi, -vi\-move, vi\-command\fP, and -.IR vi\-insert . -\fIvi\fP is equivalent to \fIvi\-command\fP; \fIemacs\fP is -equivalent to \fIemacs\-standard\fP. -.TP -.B \-l -List the names of all \fBreadline\fP functions. -.TP -.B \-p -Display \fBreadline\fP function names and bindings in such a way -that they can be re-read. -.TP -.B \-P -List current \fBreadline\fP function names and bindings. -.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. -.TP -.B \-S -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 \-q \fIfunction\fP -Query about which keys invoke the named \fIfunction\fP. -.TP -.B \-u \fIfunction\fP -Unbind all keys bound to the named \fIfunction\fP. -.TP -.B \-r \fIkeyseq\fP -Remove any current binding for \fIkeyseq\fP. -.TP -.B \-x \fIkeyseq\fP:\fIshell\-command\fP -Cause \fIshell\-command\fP to be executed whenever \fIkeyseq\fP is -entered. -When \fIshell\-command\fP is executed, the shell sets the -.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. -.TP -.B \-X -List all key sequences bound to shell commands and the associated commands -in a format that can be reused as input. -.PD -.PP -The return value is 0 unless an unrecognized option is given or an -error occurred. -.RE -.TP -\fBbreak\fP [\fIn\fP] -Exit from within a -.BR for , -.BR while , -.BR until , -or -.B select -loop. If \fIn\fP is specified, break \fIn\fP levels. -.I n -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 \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 -.IR arguments , -and return its exit status. -This is useful when defining a -function whose name is the same as a shell builtin, -retaining the functionality of the builtin within the function. -The \fBcd\fP builtin is commonly redefined this way. -The return status is false if -.I shell\-builtin -is not a shell builtin command. -.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). -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\fP|[\fB\-P\fP [\fB\-e\fP]] [\-@]] [\fIdir\fP] -Change the current directory to \fIdir\fP. -if \fIdir\fP is not supplied, the value of the -.SM -.B HOME -shell variable is the default. -Any additional arguments following \fIdir\fP are ignored. -The variable -.SM -.B CDPATH -defines the search path for the directory containing -.IR dir : -each directory name in -.SM -.B CDPATH -is searched for \fIdir\fP. -Alternative directory names in -.SM -.B CDPATH -are separated by a colon (:). A null directory name in -.SM -.B CDPATH -is the same as the current directory, i.e., ``\fB.\fP''. If -.I dir -begins with a slash (/), -then -.SM -.B CDPATH -is not used. The -.B \-P -option causes \fBcd\fP to use the physical directory structure -by resolving symbolic links while traversing \fIdir\fP and -before processing instances of \fI..\fP in \fIdir\fP (see also the -.B \-P -option to the -.B set -builtin command); the -.B \-L -option forces symbolic links to be followed by resolving the link -after processing instances of \fI..\fP in \fIdir\fP. -If \fI..\fP appears in \fIdir\fP, it is processed by removing the -immediately previous pathname component from \fIdir\fP, back to a slash -or the beginning of \fIdir\fP. -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. -On systems that support it, the \fB\-@\fP option presents the extended -attributes associated with a file as a directory. -An argument of -.B \- -is converted to -.SM -.B $OLDPWD -before the directory change is attempted. -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. -The return value is true if the directory was successfully changed; -false otherwise. -.TP -\fBcommand\fP [\fB\-pVv\fP] \fIcommand\fP [\fIarg\fP ...] -Run -.I command -with -.I args -suppressing the normal shell function lookup. Only builtin -commands or commands found in the -.SM -.B PATH -are executed. If the -.B \-p -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 -.B \-V -or -.B \-v -option is supplied, a description of -.I command -is printed. The -.B \-v -option causes a single word indicating the command or filename -used to invoke -.I command -to be displayed; the -.B \-V -option produces a more verbose description. -If the -.B \-V -or -.B \-v -option is supplied, the exit status is 0 if -.I command -was found, and 1 if not. If neither option is supplied and -an error occurred or -.I command -cannot be found, the exit status is 127. Otherwise, the exit status of the -.B command -builtin is the exit status of -.IR command . -.TP -\fBcompgen\fP [\fIoption\fP] [\fIword\fP] -Generate possible completion matches for \fIword\fP according to -the \fIoption\fPs, which may be any option accepted by the -.B complete -builtin with the exception of \fB\-p\fP and \fB\-r\fP, and write -the matches to the standard output. -When using the \fB\-F\fP or \fB\-C\fP options, the various shell variables -set by the programmable completion facilities, while available, will not -have useful values. -.sp 1 -The matches will be generated in the same way as if the programmable -completion code had generated them directly from a completion specification -with the same flags. -If \fIword\fP is specified, only those completions matching \fIword\fP -will be displayed. -.sp 1 -The return value is true unless an invalid option is supplied, or no -matches were generated. -.TP -\fBcomplete\fP [\fB\-abcdefgjksuv\fP] [\fB\-o\fP \fIcomp-option\fP] [\fB\-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\-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, -existing completion specifications are printed in a way that allows -them to be reused as input. -The \fB\-r\fP option removes a completion specification for -each \fIname\fP, or, if no \fIname\fPs are supplied, all -completion specifications. -The \fB\-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. -.sp 1 -The process of applying these completion specifications when word completion -is attempted is described above under \fBProgrammable Completion\fP. -.sp 1 -Other options, if specified, have the following meanings. -The arguments to the \fB\-G\fP, \fB\-W\fP, and \fB\-X\fP options -(and, if necessary, the \fB\-P\fP and \fB\-S\fP options) -should be quoted to protect them from expansion before the -.B complete -builtin is invoked. -.RS -.PD 0 -.TP 8 -\fB\-o\fP \fIcomp-option\fP -The \fIcomp-option\fP controls several aspects of the compspec's behavior -beyond the simple generation of completions. -\fIcomp-option\fP may be one of: -.RS -.TP 8 -.B bashdefault -Perform the rest of the default \fBbash\fP completions if the compspec -generates no matches. -.TP 8 -.B default -Use readline's default filename completion if the compspec generates -no matches. -.TP 8 -.B dirnames -Perform directory name completion if the compspec generates no matches. -.TP 8 -.B filenames -Tell readline that the compspec generates filenames, so it can perform any -filename\-specific processing (like adding a slash to directory names, -quoting special characters, or suppressing trailing spaces). -Intended to be used with shell functions. -.TP 8 -.B noquote -Tell readline not to quote the completed words if they are filenames -(quoting filenames is the default). -.TP 8 -.B nospace -Tell readline not to append a space (the default) to words completed at -the end of the line. -.TP 8 -.B plusdirs -After any matches defined by the compspec are generated, -directory name completion is attempted and any -matches are added to the results of the other actions. -.RE -.TP 8 -\fB\-A\fP \fIaction\fP -The \fIaction\fP may be one of the following to generate a list of possible -completions: -.RS -.TP 8 -.B alias -Alias names. May also be specified as \fB\-a\fP. -.TP 8 -.B arrayvar -Array variable names. -.TP 8 -.B binding -\fBReadline\fP key binding names. -.TP 8 -.B builtin -Names of shell builtin commands. May also be specified as \fB\-b\fP. -.TP 8 -.B command -Command names. May also be specified as \fB\-c\fP. -.TP 8 -.B directory -Directory names. May also be specified as \fB\-d\fP. -.TP 8 -.B disabled -Names of disabled shell builtins. -.TP 8 -.B enabled -Names of enabled shell builtins. -.TP 8 -.B export -Names of exported shell variables. May also be specified as \fB\-e\fP. -.TP 8 -.B file -File names. May also be specified as \fB\-f\fP. -.TP 8 -.B function -Names of shell functions. -.TP 8 -.B group -Group names. May also be specified as \fB\-g\fP. -.TP 8 -.B helptopic -Help topics as accepted by the \fBhelp\fP builtin. -.TP 8 -.B hostname -Hostnames, as taken from the file specified by the -.SM -.B HOSTFILE -shell variable. -.TP 8 -.B job -Job names, if job control is active. May also be specified as \fB\-j\fP. -.TP 8 -.B keyword -Shell reserved words. May also be specified as \fB\-k\fP. -.TP 8 -.B running -Names of running jobs, if job control is active. -.TP 8 -.B service -Service names. May also be specified as \fB\-s\fP. -.TP 8 -.B setopt -Valid arguments for the \fB\-o\fP option to the \fBset\fP builtin. -.TP 8 -.B shopt -Shell option names as accepted by the \fBshopt\fP builtin. -.TP 8 -.B signal -Signal names. -.TP 8 -.B stopped -Names of stopped jobs, if job control is active. -.TP 8 -.B user -User names. May also be specified as \fB\-u\fP. -.TP 8 -.B variable -Names of all shell variables. May also be specified as \fB\-v\fP. -.RE -.TP 8 -\fB\-C\fP \fIcommand\fP -\fIcommand\fP is executed in a subshell environment, and its output is -used as the possible completions. -.TP 8 -\fB\-F\fP \fIfunction\fP -The shell function \fIfunction\fP is executed in the current shell -environment. -When the function is executed, -the first argument (\fB$1\fP) is the name of the command whose arguments are -being completed, -the second argument (\fB$2\fP) is the word being completed, -and the third argument (\fB$3\fP) is the word preceding the word being -completed on the current command line. -When it finishes, the possible completions are retrieved from the value -of the -.SM -.B COMPREPLY -array variable. -.TP 8 -\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 -after all other options have been applied. -.TP 8 -\fB\-S\fP \fIsuffix\fP -\fIsuffix\fP is appended to each possible completion -after all other options have been applied. -.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 -other than \fB\-p\fP or \fB\-r\fP is supplied without a \fIname\fP -argument, an attempt is made to remove a completion specification for -a \fIname\fP for which no specification exists, or -an error occurs adding a completion specification. -.RE -.TP -\fBcompopt\fP [\fB\-o\fP \fIoption\fP] [\fB\-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-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. -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. -.TP -\fBcontinue\fP [\fIn\fP] -Resume the next iteration of the enclosing -.BR for , -.BR while , -.BR until , -or -.B select -loop. -If -.I n -is specified, resume at the \fIn\fPth enclosing loop. -.I n -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 \fIn\fP is not greater than or equal to 1. -.TP -\fBdeclare\fP [\fB\-aAfFgilnrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...] -.PD 0 -.TP -\fBtypeset\fP [\fB\-aAfFgilnrtux\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. -The -.B \-p -option will display the attributes and values of each -.IR name . -When -.B \-p -is used with \fIname\fP arguments, additional options, -other than \fB\-f\fP and \fB\-F\fP, 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. -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 . -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: -.RS -.PD 0 -.TP -.B \-a -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 \-f -Use function names only. -.TP -.B \-i -The variable is treated as an integer; arithmetic evaluation (see -.SM -.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 -converted to lower-case. -The upper-case attribute is disabled. -.TP -.B \-n -Give each \fIname\fP the \fInameref\fP attribute, making -it a name reference to another variable. -That other variable is defined by the value of \fIname\fP. -All references, assignments, and attribute modifications -to \fIname\fP, except for changing the -\fB\-n\fP attribute itself, are performed on the variable referenced by -\fIname\fP's value. -The nameref attribute cannot be applied to array variables. -.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 exceptions that \fB+a\fP -may not be used to destroy an array variable and \fB+r\fP will not -remove the readonly attribute. -When used in a function, -.B declare -and -.B typeset -make each -\fIname\fP local, as with the -.B local -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. -When using \fB\-a\fP or \fB\-A\fP and the compound assignment syntax to -create array variables, additional attributes do not take effect until -subsequent assignments. -The return value is 0 unless an invalid option is encountered, -an attempt is made to define a function using -.if n ``\-f foo=bar'', -.if t \f(CW\-f foo=bar\fP, -an attempt is made to assign a value to a readonly variable, -an attempt is made to assign a value to an array variable without -using the compound assignment syntax (see -.B Arrays -above), one of the \fInames\fP is not a valid shell variable name, -an attempt is made to turn off readonly status for a readonly variable, -an attempt is made to turn off array status for an array variable, -or an attempt is made to display a non-existent function with \fB\-f\fP. -.RE -.TP -.B dirs [\fB\-clpv\fP] [+\fIn\fP] [\-\fIn\fP] -Without options, displays the list of currently remembered directories. -The default display is on a single line with directory names separated -by spaces. -Directories are added to the list with the -.B pushd -command; the -.B popd -command removes entries from the list. -.RS -.PD 0 -.TP -.B \-c -Clears the directory stack by deleting all of the entries. -.TP -.B \-l -Produces a listing using full pathnames; -the default listing format uses a tilde to denote the home directory. -.TP -.B \-p -Print the directory stack with one entry per line. -.TP -.B \-v -Print the directory stack with one entry per line, -prefixing each entry with its index in the stack. -.TP -\fB+\fP\fIn\fP -Displays the \fIn\fPth entry counting from the left of the list -shown by -.B dirs -when invoked without options, starting with zero. -.TP -\fB\-\fP\fIn\fP -Displays the \fIn\fPth entry counting from the right of the list -shown by -.B dirs -when invoked without options, starting with zero. -.PD -.PP -The return value is 0 unless an -invalid option is supplied or \fIn\fP indexes beyond the end -of the directory stack. -.RE -.TP -\fBdisown\fP [\fB\-ar\fP] [\fB\-h\fP] [\fIjobspec\fP ...] -Without options, remove each -.I jobspec -from the table of active jobs. -If -.I jobspec -is not present, and neither the \fB\-a\fP nor the \fB\-r\fP option -is supplied, 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 -.SM -.B SIGHUP -is not sent to the job if the shell receives a -.SM -.BR SIGHUP . -If no -.I jobspec -is supplied, the -.B \-a -option means to remove or mark all jobs; the -.B \-r -option without a -.I jobspec -argument restricts operation to running jobs. -The return value is 0 unless a -.I jobspec -does not specify a valid job. -.TP -\fBecho\fP [\fB\-neE\fP] [\fIarg\fP ...] -Output the \fIarg\fPs, separated by spaces, followed by a newline. -The return status is 0 unless a write error occurs. -If \fB\-n\fP is specified, the trailing newline is -suppressed. If the \fB\-e\fP option is given, interpretation of -the following backslash-escaped characters is enabled. The -.B \-E -option disables the interpretation of these escape characters, -even on systems where they are interpreted by default. -The \fBxpg_echo\fP shell option may be used to -dynamically determine whether or not \fBecho\fP expands these -escape characters by default. -.B echo -does not interpret \fB\-\-\fP to mean the end of options. -.B echo -interprets the following escape sequences: -.RS -.PD 0 -.TP -.B \ea -alert (bell) -.TP -.B \eb -backspace -.TP -.B \ec -suppress further output -.TP -.B \ee -.TP -.B \eE -an escape character -.TP -.B \ef -form feed -.TP -.B \en -new line -.TP -.B \er -carriage return -.TP -.B \et -horizontal tab -.TP -.B \ev -vertical tab -.TP -.B \e\e -backslash -.TP -.B \e0\fInnn\fP -the eight-bit character whose value is the octal value \fInnn\fP -(zero to three octal digits) -.TP -.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 -\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, -even though the shell normally searches for builtins before disk commands. -If \fB\-n\fP is used, each \fIname\fP -is disabled; otherwise, -\fInames\fP are enabled. For example, to use the -.B test -binary found via the -.SM -.B PATH -instead of the shell builtin version, run -.if t \f(CWenable -n test\fP. -.if n ``enable -n test''. -The -.B \-f -option means to load the new builtin command -.I name -from shared object -.IR filename , -on systems that support dynamic loading. The -.B \-d -option will delete a builtin previously loaded with -.BR \-f . -If no \fIname\fP arguments are given, or if the -.B \-p -option is supplied, a list of shell builtins is printed. -With no other option arguments, the list consists of all enabled -shell builtins. -If \fB\-n\fP is supplied, only disabled builtins are printed. -If \fB\-a\fP is supplied, the list printed includes all builtins, with an -indication of whether or not each is enabled. -If \fB\-s\fP is supplied, the output is restricted to the POSIX -\fIspecial\fP builtins. -The return value is 0 unless a -.I name -is not a shell builtin or there is an error loading a new builtin -from a shared object. -.TP -\fBeval\fP [\fIarg\fP ...] -The \fIarg\fPs are read and concatenated together into a single -command. This command is then read and executed by the shell, and -its exit status is returned as the value of -.BR eval . -If there are no -.IR args , -or only null arguments, -.B eval -returns 0. -.TP -\fBexec\fP [\fB\-cl\fP] [\fB\-a\fP \fIname\fP] [\fIcommand\fP [\fIarguments\fP]] -If -.I command -is specified, it replaces the shell. -No new process is created. The -.I arguments -become the arguments to \fIcommand\fP. -If the -.B \-l -option is supplied, -the shell places a dash at the beginning of the zeroth argument passed to -.IR command . -This is what -.IR login (1) -does. The -.B \-c -option causes -.I command -to be executed with an empty environment. If -.B \-a -is supplied, the shell passes -.I name -as the zeroth argument to the executed command. -If -.I command -cannot be executed for some reason, a non-interactive shell exits, -unless the -.B execfail -shell option -is enabled. In that case, it returns failure. -An interactive shell returns failure if the file cannot be executed. -If -.I command -is not specified, any redirections take effect in the current shell, -and the return status is 0. If there is a redirection error, the -return status is 1. -.TP -\fBexit\fP [\fIn\fP] -Cause the shell to exit -with a status of \fIn\fP. If -.I n -is omitted, the exit status -is that of the last command executed. -A trap on -.SM -.B EXIT -is executed before the shell terminates. -.TP -\fBexport\fP [\fB\-fn\fP\^] [\fIname\fP[=\fIword\fP]] ... -.PD 0 -.TP -.B export \-p -.PD -The supplied -.I names -are marked for automatic export to the environment of -subsequently executed commands. If the -.B \-f -option is given, -the -.I names -refer to functions. -If no -.I names -are given, or if the -.B \-p -option is supplied, a list -of names of all exported variables is printed. -The -.B \-n -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, -one of the \fInames\fP is not a valid shell variable name, or -.B \-f -is supplied with a -.I name -that is not a function. -.TP -\fBfc\fP [\fB\-e\fP \fIename\fP] [\fB\-lnr\fP] [\fIfirst\fP] [\fIlast\fP] -.PD 0 -.TP -\fBfc\fP \fB\-s\fP [\fIpat\fP=\fIrep\fP] [\fIcmd\fP] -.PD -The first form selects a range of commands from -.I first -to -.I last -from the history list and displays or edits and re-executes them. -.I First -and -.I last -may be specified as a string (to locate the last command beginning -with that string) or as a number (an index into the history list, -where a negative number is used as an offset from the current -command number). If -.I last -is not specified it is set to -the current command for listing (so that -.if n ``fc \-l \-10'' -.if t \f(CWfc \-l \-10\fP -prints the last 10 commands) and to -.I first -otherwise. -If -.I first -is not specified it is set to the previous -command for editing and \-16 for listing. -.sp 1 -The -.B \-n -option suppresses -the command numbers when listing. The -.B \-r -option reverses the order of -the commands. If the -.B \-l -option is given, -the commands are listed on -standard output. Otherwise, the editor given by -.I ename -is invoked -on a file containing those commands. If -.I ename -is not given, the -value of the -.SM -.B FCEDIT -variable is used, and -the value of -.SM -.B EDITOR -if -.SM -.B FCEDIT -is not set. If neither variable is set, -.FN vi -is used. When editing is complete, the edited commands are -echoed and executed. -.sp 1 -In the second form, \fIcommand\fP is re-executed after each instance -of \fIpat\fP is replaced by \fIrep\fP. -\fICommand\fP is intepreted the same as \fIfirst\fP above. -A useful alias to use with this is -.if n ``r="fc -s"'', -.if t \f(CWr='fc \-s'\fP, -so that typing -.if n ``r cc'' -.if t \f(CWr cc\fP -runs the last command beginning with -.if n ``cc'' -.if t \f(CWcc\fP -and typing -.if n ``r'' -.if t \f(CWr\fP -re-executes the last command. -.sp 1 -If the first form is used, the return value is 0 unless an invalid -option is encountered or -.I first -or -.I last -specify history lines out of range. -If the -.B \-e -option is supplied, the return value is the value of the last -command executed or failure if an error occurs with the temporary -file of commands. If the second form is used, the return status -is that of the command re-executed, unless -.I cmd -does not specify a valid history line, in which case -.B fc -returns failure. -.TP -\fBfg\fP [\fIjobspec\fP] -Resume -.I jobspec -in the foreground, and make it the current job. -If -.I jobspec -is not present, the shell's notion of the \fIcurrent job\fP is used. -The return value is that of the command placed into the foreground, -or failure if run when job control is disabled or, when run with -job control enabled, if -.I jobspec -does not specify a valid job or -.I jobspec -specifies a job that was started without job control. -.TP -\fBgetopts\fP \fIoptstring\fP \fIname\fP [\fIargs\fP] -.B getopts -is used by shell procedures to parse positional parameters. -.I optstring -contains the option characters to be recognized; if a character -is followed by a colon, the option is expected to have an -argument, which should be separated from it by white space. -The colon and question mark characters may not be used as -option characters. -Each time it is invoked, -.B getopts -places the next option in the shell variable -.IR name , -initializing -.I name -if it does not exist, -and the index of the next argument to be processed into the -variable -.SM -.BR OPTIND . -.SM -.B OPTIND -is initialized to 1 each time the shell or a shell script -is invoked. When an option requires an argument, -.B getopts -places that argument into the variable -.SM -.BR OPTARG . -The shell does not reset -.SM -.B OPTIND -automatically; it must be manually reset between multiple -calls to -.B getopts -within the same shell invocation if a new set of parameters -is to be used. -.sp 1 -When the end of options is encountered, \fBgetopts\fP exits with a -return value greater than zero. -.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 -given in -.IR args , -.B getopts -parses those instead. -.sp 1 -.B getopts -can report errors in two ways. If the first character of -.I optstring -is a colon, -.I silent -error reporting is used. In normal operation, diagnostic messages -are printed when invalid options or missing option arguments are -encountered. -If the variable -.SM -.B OPTERR -is set to 0, no error messages will be displayed, even if the first -character of -.I optstring -is not a colon. -.sp 1 -If an invalid option is seen, -.B getopts -places ? into -.I name -and, if not silent, -prints an error message and unsets -.SM -.BR OPTARG . -If -.B getopts -is silent, -the option character found is placed in -.SM -.B OPTARG -and no diagnostic message is printed. -.sp 1 -If a required argument is not found, and -.B getopts -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 -.B getopts -is silent, then a colon (\^\fB:\fP\^) is placed in -.I name -and -.SM -.B OPTARG -is set to the option character found. -.sp 1 -.B getopts -returns true if an option, specified or unspecified, is found. -It returns false if the end of options is encountered or an -error occurs. -.TP -\fBhash\fP [\fB\-lr\fP] [\fB\-p\fP \fIfilename\fP] [\fB\-dt\fP] [\fIname\fP] -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. Any previously-remembered pathname is discarded. -If the -.B \-p -option is supplied, no path search is performed, and -.I filename -is used as the full filename of the command. -The -.B \-r -option causes the shell to forget all -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\-dms\fP] [\fIpattern\fP] -Display helpful information about builtin commands. If -.I pattern -is specified, -.B help -gives detailed help on all commands matching -.IR pattern ; -otherwise help for all the builtins and shell control structures -is printed. -.RS -.PD 0 -.TP -.B \-d -Display a short description of each \fIpattern\fP -.TP -.B \-m -Display the description of each \fIpattern\fP in a manpage-like format -.TP -.B \-s -Display only a short usage synopsis for each \fIpattern\fP -.PD -.PP -The return status is 0 unless no command matches -.IR pattern . -.RE -.TP -\fBhistory [\fIn\fP] -.PD 0 -.TP -\fBhistory\fP \fB\-c\fP -.TP -\fBhistory \-d\fP \fIoffset\fP -.TP -\fBhistory\fP \fB\-anrw\fP [\fIfilename\fP] -.TP -\fBhistory\fP \fB\-p\fP \fIarg\fP [\fIarg ...\fP] -.TP -\fBhistory\fP \fB\-s\fP \fIarg\fP [\fIarg ...\fP] -.PD -With no options, display the command -history list with line numbers. Lines listed -with a -.B * -have been modified. An argument of -.I n -lists only the last -.I n -lines. -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 -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 -is used. Options, if supplied, have the following meanings: -.RS -.PD 0 -.TP -.B \-c -Clear the history list by deleting all the entries. -.TP -\fB\-d\fP \fIoffset\fP -Delete the history entry at position \fIoffset\fP. -.TP -.B \-a -Append the ``new'' history lines (history lines entered since the -beginning of the current \fBbash\fP session) to the history file. -.TP -.B \-n -Read the history lines not already read from the history -file into the current history list. These are lines -appended to the history file since the beginning of the -current \fBbash\fP session. -.TP -.B \-r -Read the contents of the history file -and append them to the current history list. -.TP -.B \-w -Write the current history list to the history file, overwriting the -history file's contents. -.TP -.B \-p -Perform history substitution on the following \fIargs\fP and display -the result on the standard output. -Does not store the results in the history list. -Each \fIarg\fP must be quoted to disable normal history expansion. -.TP -.B \-s -Store the -.I args -in the history list as a single entry. The last command in the -history list is removed before the -.I args -are added. -.PD -.PP -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 -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 -\fBjobs\fP [\fB\-lnprs\fP] [ \fIjobspec\fP ... ] -.PD 0 -.TP -\fBjobs\fP \fB\-x\fP \fIcommand\fP [ \fIargs\fP ... ] -.PD -The first form lists the active jobs. The options have the following -meanings: -.RS -.PD 0 -.TP -.B \-l -List process IDs -in addition to the normal information. -.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 -Display only running jobs. -.TP -.B \-s -Display only stopped jobs. -.PD -.PP -If -.I jobspec -is given, output is restricted to information about that job. -The return status is 0 unless an invalid option is encountered -or an invalid -.I jobspec -is supplied. -.PP -If the -.B \-x -option is supplied, -.B jobs -replaces any -.I jobspec -found in -.I command -or -.I args -with the corresponding process group ID, and executes -.I command -passing it -.IR args , -returning its exit status. -.RE -.TP -\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 -Send the signal named by -.I sigspec -or -.I signum -to the processes named by -.I pid -or -.IR jobspec . -.I sigspec -is either a case-insensitive signal name such as -.SM -.B SIGKILL -(with or without the -.SM -.B SIG -prefix) or a signal number; -.I signum -is a signal number. -If -.I sigspec -is not present, then -.SM -.B SIGTERM -is assumed. -An argument of -.B \-l -lists the signal names. -If any arguments are supplied when -.B \-l -is given, the names of the signals corresponding to the arguments are -listed, and the return status is 0. -The \fIexit_status\fP argument to -.B \-l -is a number specifying either a signal number or the exit status of -a process terminated by a signal. -.B kill -returns true if at least one signal was successfully sent, or false -if an error occurs or an invalid option is encountered. -.TP -\fBlet\fP \fIarg\fP [\fIarg\fP ...] -Each -.I arg -is an arithmetic expression to be evaluated (see -.SM -.B "ARITHMETIC EVALUATION" -above). -If the last -.I arg -evaluates to 0, -.B let -returns 1; 0 is returned otherwise. -.TP -\fBlocal\fP [\fIoption\fP] [\fIname\fP[=\fIvalue\fP] ...] -For each argument, a local variable named -.I name -is created, and assigned -.IR value . -The \fIoption\fP can be any of the options accepted by \fBdeclare\fP. -When -.B local -is used within a function, it causes the variable -.I name -to have a visible scope restricted to that function and its children. -With no operands, -.B local -writes a list of local variables to the standard output. It is -an error to use -.B local -when not within a function. The return status is 0 unless -.B local -is used outside a function, an invalid -.I name -is supplied, or -\fIname\fP is a readonly variable. -.TP -.B logout -Exit a login shell. -.TP -\fBmapfile\fP [\fB\-n\fP \fIcount\fP] [\fB\-O\fP \fIorigin\fP] [\fB\-s\fP \fIcount\fP] [\fB\-t\fP] [\fB\-u\fP \fIfd\fP] [\fB\-C\fP \fIcallback\fP] [\fB\-c\fP \fIquantum\fP] [\fIarray\fP] -.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 -.SM -.B MAPFILE -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 newline 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. -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, \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] -Removes entries from the directory stack. With no arguments, -removes the top directory from the stack, and performs a -.B cd -to the new top directory. -Arguments, if supplied, have the following meanings: -.RS -.PD 0 -.TP -.B \-n -Suppresses the normal change of directory when removing directories -from the stack, so that only the stack is manipulated. -.TP -\fB+\fP\fIn\fP -Removes the \fIn\fPth entry counting from the left of the list -shown by -.BR dirs , -starting with zero. For example: -.if n ``popd +0'' -.if t \f(CWpopd +0\fP -removes the first directory, -.if n ``popd +1'' -.if t \f(CWpopd +1\fP -the second. -.TP -\fB\-\fP\fIn\fP -Removes the \fIn\fPth entry counting from the right of the list -shown by -.BR dirs , -starting with zero. For example: -.if n ``popd -0'' -.if t \f(CWpopd -0\fP -removes the last directory, -.if n ``popd -1'' -.if t \f(CWpopd -1\fP -the next to last. -.PD -.PP -If the -.B popd -command is successful, a -.B dirs -is performed as well, and the return status is 0. -.B popd -returns false if an invalid option is encountered, the directory stack -is empty, a non-existent directory stack entry is specified, or the -directory change fails. -.RE -.TP -\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) 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). -.TP -.B %q -causes \fBprintf\fP to output the corresponding -\fIargument\fP in a format that can be reused as shell input. -.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. -If no argument is specified, conversion behaves as if -1 had been given. -This is an exception to the usual \fBprintf\fP behavior. -.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. -.RE -.TP -\fBpushd\fP [\fB\-n\fP] [+\fIn\fP] [\-\fIn\fP] -.PD 0 -.TP -\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 -directory. With no arguments, exchanges the top two directories -and returns 0, unless the directory stack is empty. -Arguments, if supplied, have the following meanings: -.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 -\fB\-\fP\fIn\fP -Rotates the stack so that the \fIn\fPth directory -(counting from the right of the list shown by -.BR dirs , -starting with zero) is at the top. -.TP -.I dir -Adds -.I dir -to the directory stack at the top, making it the -new current working directory as if it had been supplied as the argument -to the \fBcd\fP builtin. -.PD -.PP -If the -.B pushd -command is successful, a -.B dirs -is performed as well. -If the first form is used, -.B pushd -returns 0 unless the cd to -.I dir -fails. With the second form, -.B pushd -returns 0 unless the directory stack is empty, -a non-existent directory stack element is specified, -or the directory change to the specified new current directory -fails. -.RE -.TP -\fBpwd\fP [\fB\-LP\fP] -Print the absolute pathname of the current working directory. -The pathname printed contains no symbolic links if the -.B \-P -option is supplied or the -.B \-o physical -option to the -.B set -builtin command is enabled. -If the -.B \-L -option is used, the pathname printed may contain symbolic links. -The return status is 0 unless an error occurs while -reading the name of the current directory or an -invalid option is supplied. -.TP -\fBread\fP [\fB\-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 -.IR name , -the second word to the second -.IR name , -and so on, with leftover words and their intervening separators assigned -to the last -.IR name . -If there are fewer words read from the input stream than names, -the remaining names are assigned empty values. -The characters in -.SM -.B IFS -are used to split the line into words using the same rules the shell -uses for expansion (described above under \fBWord Splitting\fP). -The backslash character (\fB\e\fP) may be used to remove any special -meaning for the next character read and for line continuation. -Options, if supplied, have the following meanings: -.RS -.PD 0 -.TP -.B \-a \fIaname\fP -The words are assigned to sequential indices -of the array variable -.IR aname , -starting at 0. -.I aname -is unset before any new values are assigned. -Other \fIname\fP arguments are ignored. -.TP -.B \-d \fIdelim\fP -The first character of \fIdelim\fP is used to terminate the input line, -rather than newline. -.TP -.B \-e -If the standard input -is coming from a terminal, -.B readline -(see -.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, 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 -trailing newline, before attempting to read any input. The prompt -is displayed only if input is coming from a terminal. -.TP -.B \-r -Backslash does not act as an escape character. -The backslash is considered to be part of the line. -In particular, a backslash-newline pair may not be used as a line -continuation. -.TP -.B \-s -Silent mode. If input is coming from a terminal, characters are -not echoed. -.TP -.B \-t \fItimeout\fP -Cause \fBread\fP to time out and return failure if a complete line of -input (or a specified number of characters) -is not read within \fItimeout\fP seconds. -\fItimeout\fP may be a decimal number with a fractional portion following -the decimal point. -This option is only effective if \fBread\fP is reading input from a -terminal, pipe, or other special file; it has no effect when reading -from regular files. -If \fBread\fP times out, \fBread\fP saves any partial input read into -the specified variable \fIname\fP. -If \fItimeout\fP is 0, \fBread\fP returns immediately, without trying to -read any data. The exit status is 0 if input is available on -the specified file descriptor, non-zero 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 -.I names -are supplied, the line read is assigned to the variable -.SM -.BR REPLY . -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), -a variable assignment error (such as assigning to a readonly variable) occurs, -or an invalid file descriptor is supplied as the argument to \fB\-u\fP. -.RE -.TP -\fBreadonly\fP [\fB\-aAf\fP] [\fB\-p\fP] [\fIname\fP[=\fIword\fP] ...] -.PD -The given -\fInames\fP are marked readonly; the values of these -.I names -may not be changed by subsequent assignment. -If the -.B \-f -option is supplied, the functions corresponding to the -\fInames\fP are so -marked. -The -.B \-a -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 -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 -is not a valid shell variable name, or -.B \-f -is supplied with a -.I name -that is not a function. -.TP -\fBreturn\fP [\fIn\fP] -Causes a function to stop executing and return the value specified by -.I n -to its caller. -If -.I n -is omitted, the return status is that of the last command -executed in the function body. -If \fBreturn\fP is executed by a trap handler, the last command used to -determine the status is the last command executed before the trap handler. -if \fBreturn\fP is executed during a \fBDEBUG\fP trap, the last command -used to determine the status is the last command executed by the trap -handler before \fBreturn\fP was invoked. -If -.B return -is used outside a function, -but during execution of a script by the -.B . -(\fBsource\fP) command, it causes the shell to stop executing -that script and return either -.I n -or the exit status of the last command executed within the -script as the exit status of the script. -If \fIn\fP is supplied, the return value is its least significant -8 bits. -The return status is non-zero if -.B return -is supplied a non-numeric argument, or -is used outside a -function and not during execution of a script by \fB.\fP\^ or \fBsource\fP. -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\-name\fP] [\fIarg\fP ...] -.PD 0 -.TP -\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 -for setting or resetting the currently-set variables. -Read-only variables cannot be reset. -In \fIposix\fP mode, 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 option processing are treated -as values for the positional parameters and are assigned, in order, to -.BR $1 , -.BR $2 , -.B ... -.BR $\fIn\fP . -Options, if specified, have the following meanings: -.RS -.PD 0 -.TP 8 -.B \-a -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 -immediately, rather than before the next primary prompt. This is -effective only when job control is enabled. -.TP 8 -.B \-e -Exit immediately if a -\fIpipeline\fP (which may consist of a single \fIsimple command\fP), -a \fIlist\fP, -or a \fIcompound 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 the command list immediately following a -.B while -or -.B until -keyword, -part of the test following the -.B if -or -.B elif -reserved words, part of any command executed in a -.B && -or -.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 with -.BR ! . -If a compound command other than a subshell -returns a non-zero status because a command failed -while \fB\-e\fP was being ignored, the shell does not 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. -.if t .sp 0.5 -.if n .sp 1 -If a compound command or shell function executes in a context -where \fB\-e\fP is being ignored, -none of the commands executed within the compound command or function body -will be affected by the \fB\-e\fP setting, even if \fB\-e\fP is set -and a command returns a failure status. -If a compound command or shell function sets \fB\-e\fP while executing in -a context where \fB\-e\fP is ignored, that setting will not have any -effect until the compound command or the command containing the function -call completes. -.TP 8 -.B \-f -Disable pathname expansion. -.TP 8 -.B \-h -Remember the location of commands as they are looked up for execution. -This is enabled by default. -.TP 8 -.B \-k -All arguments in the form of assignment statements -are placed in the environment for a command, not just -those that precede the command name. -.TP 8 -.B \-m -Monitor mode. Job control is enabled. This option is on -by default for interactive shells on systems that support -it (see -.SM -.B JOB CONTROL -above). -All processes run in a separate process group. -When a background job completes, the shell prints a line -containing its exit status. -.TP 8 -.B \-n -Read commands but do not execute them. This may be used to -check a shell script for syntax errors. This is ignored by -interactive shells. -.TP 8 -.B \-o \fIoption\-name\fP -The \fIoption\-name\fP can be one of the following: -.RS -.TP 8 -.B allexport -Same as -.BR \-a . -.TP 8 -.B braceexpand -Same as -.BR \-B . -.TP 8 -.B emacs -Use an emacs-style command line editing interface. This is enabled -by default when the shell is interactive, unless the shell is started -with the -.B \-\-noediting -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 . -.TP 8 -.B functrace -Same as -.BR \-T . -.TP 8 -.B hashall -Same as -.BR \-h . -.TP 8 -.B histexpand -Same as -.BR \-H . -.TP 8 -.B history -Enable command history, as described above under -.SM -.BR HISTORY . -This option is on by default in interactive shells. -.TP 8 -.B ignoreeof -The effect is as if the shell command -.if t \f(CWIGNOREEOF=10\fP -.if n ``IGNOREEOF=10'' -had been executed -(see -.B Shell Variables -above). -.TP 8 -.B keyword -Same as -.BR \-k . -.TP 8 -.B monitor -Same as -.BR \-m . -.TP 8 -.B noclobber -Same as -.BR \-C . -.TP 8 -.B noexec -Same as -.BR \-n . -.TP 8 -.B noglob -Same as -.BR \-f . -.TP 8 -.B nolog -Currently ignored. -.TP 8 -.B notify -Same as -.BR \-b . -.TP 8 -.B nounset -Same as -.BR \-u . -.TP 8 -.B onecmd -Same as -.BR \-t . -.TP 8 -.B physical -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 standard to match the standard (\fIposix mode\fP). -See -.SM -.B "SEE ALSO" -below for a reference to a document that details how posix mode affects -bash's behavior. -.TP 8 -.B privileged -Same as -.BR \-p . -.TP 8 -.B verbose -Same as -.BR \-v . -.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 -.BR \-x . -.sp .5 -.PP -If -.B \-o -is supplied with no \fIoption\-name\fP, the values of the current options are -printed. -If -.B +o -is supplied with no \fIoption\-name\fP, a series of -.B set -commands to recreate the current option settings is displayed on -the standard output. -.RE -.TP 8 -.B \-p -Turn on -.I privileged -mode. In this mode, the -.SM -.B $ENV -and -.SM -.B $BASH_ENV -files are not processed, shell functions are not inherited from the -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 -real user (group) id, and the \fB\-p\fP option is not supplied, these actions -are taken and the effective user id is set to the real user id. -If the \fB\-p\fP option is supplied at startup, the effective user id is -not reset. -Turning this option off causes the effective user -and group ids to be set to the real user and group ids. -.TP 8 -.B \-t -Exit after reading and executing one command. -.TP 8 -.B \-u -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 or parameter, the shell prints an error message, and, -if not interactive, exits with a non-zero status. -.TP 8 -.B \-v -Print shell input lines as they are read. -.TP 8 -.B \-x -After expanding each \fIsimple command\fP, -\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 -or associated word list. -.TP 8 -.B \-B -The shell performs brace expansion (see -.B Brace Expansion -above). This is on by default. -.TP 8 -.B \-C -If set, -.B bash -does not overwrite an existing file with the -.BR > , -.BR >& , -and -.B <> -redirection operators. This may be overridden when -creating output files by using the redirection operator -.B >| -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 ! -style history substitution. This option is on by -default when the shell is interactive. -.TP 8 -.B \-P -If set, the shell does not resolve symbolic links when executing -commands such as -.B cd -that change the current working directory. It uses the -physical directory structure instead. By default, -.B bash -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 -\fIarg\fPs, even if some of them begin with a -.BR \- . -.TP 8 -.B \- -Signal the end of options, cause all remaining \fIarg\fPs to be -assigned to the positional parameters. The -.B \-x -and -.B \-v -options are turned off. -If there are no \fIarg\fPs, -the positional parameters remain unchanged. -.PD -.PP -The options are off by default unless otherwise noted. -Using + rather than \- causes these options to be turned off. -The options can also be specified as arguments to an invocation of -the shell. -The current set of options may be found in -.BR $\- . -The return status is always true unless an invalid option is encountered. -.RE -.TP -\fBshift\fP [\fIn\fP] -The positional parameters from \fIn\fP+1 ... are renamed to -.B $1 -.B .... -Parameters represented by the numbers \fB$#\fP -down to \fB$#\fP\-\fIn\fP+1 are unset. -.I n -must be a non-negative number less than or equal to \fB$#\fP. -If -.I n -is 0, no parameters are changed. -If -.I n -is not given, it is assumed to be 1. -If -.I n -is greater than \fB$#\fP, the positional parameters are not changed. -The return status is greater than zero if -.I n -is greater than -.B $# -or less than zero; otherwise 0. -.TP -\fBshopt\fP [\fB\-pqsu\fP] [\fB\-o\fP] [\fIoptname\fP ...] -Toggle the values of settings controlling optional shell behavior. -The settings can be either those listed below, or, if the -.B \-o -option is used, those available with the -.B \-o -option to the \fBset\fP builtin command. -With no options, or with the -.B \-p -option, a list of all settable options is displayed, with -an indication of whether or not each is set. -The \fB\-p\fP option causes output to be displayed in a form that -may be reused as input. -Other options have the following meanings: -.RS -.PD 0 -.TP -.B \-s -Enable (set) each \fIoptname\fP. -.TP -.B \-u -Disable (unset) each \fIoptname\fP. -.TP -.B \-q -Suppresses normal output (quiet mode); the return status indicates -whether the \fIoptname\fP is set or unset. -If multiple \fIoptname\fP arguments are given with -.BR \-q , -the return status is zero if all \fIoptnames\fP are enabled; non-zero -otherwise. -.TP -.B \-o -Restricts the values of \fIoptname\fP to be those defined for the -.B \-o -option to the -.B set -builtin. -.PD -.PP -If either -.B \-s -or -.B \-u -is used with no \fIoptname\fP arguments, -.B shopt -shows only those options which are set or unset, respectively. -Unless otherwise noted, the \fBshopt\fP options are disabled (unset) -by default. -.PP -The return status when listing options is zero if all \fIoptnames\fP -are enabled, non-zero otherwise. When setting or unsetting options, -the return status is zero unless an \fIoptname\fP is not a valid shell -option. -.PP -The list of \fBshopt\fP options is: -.if t .sp .5v -.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 -builtin command that -is not a directory is assumed to be the name of a variable whose -value is the directory to change to. -.TP 8 -.B cdspell -If set, minor errors in the spelling of a directory component in a -.B cd -command will be corrected. -The errors checked for are transposed characters, -a missing character, and one character too many. -If a correction is found, the corrected filename is printed, -and the command proceeds. -This option is only used by interactive shells. -.TP 8 -.B checkhash -If set, \fBbash\fP checks that a command found in the hash -table exists before trying to execute it. If a hashed command no -longer exists, a normal path search is performed. -.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 -.SM -.B "JOB CONTROL" -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 -.SM -.B LINES -and -.SM -.BR COLUMNS . -.TP 8 -.B cmdhist -If set, -.B bash -attempts to save all lines of a multiple-line -command in the same history entry. This allows -easy re-editing of multi-line commands. -.TP 8 -.B compat31 -If set, -.B bash -changes its behavior to that of version 3.1 with respect to quoted -arguments to the \fB[[\fP conditional command's \fB=~\fP operator -and 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 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 (see previous item). -.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 description of -\fBcompat31\fP) -and the effect of interrupting a command list. -Bash versions 4.0 and later interrupt the list as if the shell received the -interrupt; previous versions continue with the next command in the list. -.TP 8 -.B compat41 -If set, -.BR bash , -when in \fIposix\fP 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 compat42 -If set, -.B bash -does not process the replacement string in the pattern substitution word -expansion using quote removal. -.TP 8 -.B complete_fullquote -If set, -.B bash -quotes all shell metacharacters in filenames and directory names when -performing completion. -If not set, -.B bash -removes metacharacters such as the dollar sign from the set of -characters that will be quoted in completed filenames -when these metacharacters appear in shell variable references in words to be -completed. -This means that dollar signs in variable names that expand to directories -will not be quoted; -however, any dollar signs appearing in filenames will not be quoted, either. -This is active only when bash is using backslashes to quote completed -filenames. -This variable is set by default, which is the default bash behavior in -versions through 4.2. -.TP 8 -.B direxpand -If set, -.B bash -replaces directory names with the results of word expansion when performing -filename completion. This changes the contents of the readline editing -buffer. -If not set, -.B bash -attempts to preserve what the user typed. -.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 -includes filenames beginning with a `.' in the results of pathname -expansion. -.TP 8 -.B execfail -If set, a non-interactive shell will not exit if -it cannot execute the file specified as an argument to the -.B exec -builtin command. An interactive shell does not exit if -.B exec -fails. -.TP 8 -.B expand_aliases -If set, aliases are expanded as described above under -.SM -.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), the shell simulates -a call to \fBreturn\fP. -.TP -.B 4. -.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 -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 -\fBERR\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 -.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 -.SM -.BR FIGNORE . -This option is enabled by default. -.TP 8 -.B globasciiranges -If set, range expressions used in pattern matching bracket expressions (see -.SM -.B Pattern Matching -above) behave as if in the traditional C locale when performing -comparisons. That is, the current locale's collating sequence -is not taken into account, so -.B b -will not collate between -.B A -and -.BR B , -and upper-case and lower-case ASCII characters will collate together. -.TP 8 -.B globstar -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 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 -.SM -.B HISTFILE -variable when the shell exits, rather than overwriting the file. -.TP 8 -.B histreedit -If set, and -.B readline -is being used, a user is given the opportunity to re-edit a -failed history substitution. -.TP 8 -.B histverify -If set, and -.B readline -is being used, the results of history substitution are not immediately -passed to the shell parser. Instead, the resulting line is loaded into -the \fBreadline\fP editing buffer, allowing further modification. -.TP 8 -.B hostcomplete -If set, and -.B readline -is being used, \fBbash\fP will attempt to perform hostname completion when a -word containing a \fB@\fP is being completed (see -.B Completing -under -.SM -.B READLINE -above). -This is enabled by default. -.TP 8 -.B huponexit -If set, \fBbash\fP will send -.SM -.B SIGHUP -to all jobs when an interactive login shell exits. -.TP 8 -.B interactive_comments -If set, allow a word beginning with -.B # -to cause that word and all remaining characters on that -line to be ignored in an interactive shell (see -.SM -.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 -option is enabled, multi-line commands are saved to the history with -embedded newlines rather than using semicolon separators where possible. -.TP 8 -.B login_shell -The shell sets this option if it is started as a login shell (see -.SM -.B "INVOCATION" -above). -The value may not be changed. -.TP 8 -.B mailwarn -If set, and a file that \fBbash\fP is checking for mail has been -accessed since the last time it was checked, the message ``The mail in -\fImailfile\fP has been read'' is displayed. -.TP 8 -.B no_empty_cmd_completion -If set, and -.B readline -is being used, -.B bash -will not attempt to search the -.SM -.B PATH -for possible completions when -completion is attempted on an empty line. -.TP 8 -.B nocaseglob -If set, -.B bash -matches filenames in a case\-insensitive fashion when performing pathname -expansion (see -.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 -allows patterns which match no -files (see -.B Pathname Expansion -above) -to expand to a null string, rather than themselves. -.TP 8 -.B progcomp -If set, the programmable completion facilities (see -\fBProgrammable Completion\fP above) are enabled. -This option is enabled by default. -.TP 8 -.B promptvars -If set, prompt strings undergo -parameter expansion, command substitution, arithmetic -expansion, and quote removal after being expanded as described in -.SM -.B PROMPTING -above. This option is enabled by default. -.TP 8 -.B restricted_shell -The shell sets this option if it is started in restricted mode (see -.SM -.B "RESTRICTED SHELL" -below). -The value may not be changed. -This is not reset when the startup files are executed, allowing -the startup files to discover whether or not a shell is restricted. -.TP 8 -.B shift_verbose -If set, the -.B shift -builtin prints an error message when the shift count exceeds the -number of positional parameters. -.TP 8 -.B sourcepath -If set, the -\fBsource\fP (\fB.\fP) builtin uses the value of -.SM -.B PATH -to find the directory containing the file supplied as an argument. -This option is enabled by default. -.TP 8 -.B xpg_echo -If set, the \fBecho\fP builtin expands backslash-escape sequences -by default. -.RE -.PD -.TP -\fBsuspend\fP [\fB\-f\fP] -Suspend the execution of this shell until it receives a -.SM -.B SIGCONT -signal. A login shell cannot be suspended; the -.B \-f -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 -\fBtest\fP \fIexpr\fP -.PD 0 -.TP -\fB[\fP \fIexpr\fP \fB]\fP -Return a status of 0 (true) or 1 (false) depending on -the evaluation of the conditional expression -.IR expr . -Each operator and operand must be a separate argument. -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. -Operator precedence is used when there are five or more arguments. -.RS -.PD 0 -.TP -.B ! \fIexpr\fP -True if -.I expr -is false. -.TP -.B ( \fIexpr\fP ) -Returns the value of \fIexpr\fP. -This may be used to override the normal precedence of operators. -.TP -\fIexpr1\fP \-\fBa\fP \fIexpr2\fP -True if both -.I expr1 -and -.I expr2 -are true. -.TP -\fIexpr1\fP \-\fBo\fP \fIexpr2\fP -True if either -.I expr1 -or -.I expr2 -is true. -.PD -.PP -\fBtest\fP and \fB[\fP evaluate conditional -expressions using a set of rules based on the number of arguments. -.if t .sp 0.5 -.if n .sp 1 -.PD 0 -.TP -0 arguments -The expression is false. -.TP -1 argument -The expression is true if and only if the argument is not null. -.TP -2 arguments -If the first argument is \fB!\fP, the expression is true if and -only if the second argument is null. -If the first argument is one of the unary conditional operators listed above -under -.SM -.BR "CONDITIONAL EXPRESSIONS" , -the expression is true if the unary test is true. -If the first argument is not a valid unary conditional operator, the expression -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 -.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. -.TP -4 arguments -If the first argument is \fB!\fP, the result is the negation of -the three-argument expression composed of the remaining arguments. -Otherwise, the expression is parsed and evaluated according to -precedence using the rules listed above. -.TP -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 -.B times -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 ...] -The command -.I arg -is to be read and executed when the shell receives -signal(s) -.IR sigspec . -If -.I arg -is absent (and there is a single \fIsigspec\fP) or -.BR \- , -each specified signal is -reset to its original disposition (the value it had -upon entrance to the shell). -If -.I arg -is the null string the signal specified by each -.I sigspec -is ignored by the shell and by the commands it invokes. -If -.I arg -is not present and -.B \-p -has been supplied, then the trap commands associated with each -.I sigspec -are displayed. -If no arguments are supplied or if only -.B \-p -is given, -.B trap -prints the list of commands associated with each signal. -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 -.SM -.B SIG -prefix is optional. -.if t .sp 0.5 -.if n .sp 1 -If a -.I sigspec -is -.SM -.B EXIT -(0) the command -.I arg -is executed on exit from the shell. -If a -.I sigspec -is -.SM -.BR DEBUG , -the command -.I arg -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 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 -is executed whenever a -a pipeline (which may consist of a single simple -command), a list, or a compound command returns a -non\-zero exit status, -subject to the following conditions. -The -.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 || -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 using -.BR ! . -These are the same conditions obeyed by the \fBerrexit\fP (\fB\-e\fP) option. -.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 subshell or subshell environment when one is created. -The return status is false if any -.I sigspec -is invalid; otherwise -.B trap -returns true. -.TP -\fBtype\fP [\fB\-aftpP\fP] \fIname\fP [\fIname\fP ...] -With no options, -indicate how each -.I name -would be interpreted if used as a command name. -If the -.B \-t -option is used, -.B type -prints a string which is one of -.IR alias , -.IR keyword , -.IR function , -.IR builtin , -or -.I file -if -.I name -is an alias, shell reserved word, function, builtin, or disk file, -respectively. -If the -.I name -is not found, then nothing is printed, and an exit status of false -is returned. -If the -.B \-p -option is used, -.B type -either returns the name of the disk file -that would be executed if -.I name -were specified as a command name, -or nothing if -.if t \f(CWtype -t name\fP -.if n ``type -t name'' -would not return -.IR file . -The -.B \-P -option forces a -.SM -.B PATH -search for each \fIname\fP, even if -.if t \f(CWtype -t name\fP -.if n ``type -t name'' -would not return -.IR file . -If a command is hashed, -.B \-p -and -.B \-P -print the hashed value, which is not necessarily the file that appears -first in -.SM -.BR PATH . -If the -.B \-a -option is used, -.B type -prints all of the places that contain -an executable named -.IR name . -This includes aliases and functions, -if and only if the -.B \-p -option is not also used. -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 all of the arguments are found, false if -any are not found. -.TP -\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 \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 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 -printed, unless the \fB\-H\fP option is given. When more than one -resource is specified, the limit name and unit are printed before the value. -Other options are interpreted as follows: -.RS -.PD 0 -.TP -.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 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 -.TP -.B \-m -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 -allow this value to be set) -.TP -.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 -.B \-t -The maximum amount of cpu time in seconds -.TP -.B \-u -The maximum number of processes available to a single user -.TP -.B \-v -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 -.TP -.B \-T -The maximum number of threads -.PD -.PP -If -.I limit -is given, and the -.B \-a -option is not used, -\fIlimit\fP is the new value of the specified resource. -If no option is given, then -.B \-f -is assumed. Values are in 1024-byte increments, except for -.BR \-t , -which is in seconds; -.BR \-p , -which is in units of 512-byte blocks; -and -.BR \-T , -.BR \-b , -.BR \-n , -and -.BR \-u , -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] -The user file-creation mask is set to -.IR mode . -If -.I mode -begins with a digit, it -is interpreted as an octal number; otherwise -it is interpreted as a symbolic mode mask similar -to that accepted by -.IR chmod (1). -If -.I mode -is omitted, the current value of the mask is printed. -The -.B \-S -option causes the mask to be printed in symbolic form; the -default output is an octal number. -If the -.B \-p -option is supplied, and -.I mode -is omitted, the output is in a form that may be reused as input. -The return status is 0 if the mode was successfully changed or if -no \fImode\fP argument was supplied, and false otherwise. -.TP -\fBunalias\fP [\-\fBa\fP] [\fIname\fP ...] -Remove each \fIname\fP from the list of defined aliases. If -.B \-a -is supplied, all alias definitions are removed. The return -value is true unless a supplied -.I name -is not a defined alias. -.TP -\fBunset\fP [\-\fBfv\fP] [\-\fBn\fP] [\fIname\fP ...] -For each -.IR name , -remove the corresponding variable or function. -If the -.B \-v -option is given, each -.I name -refers to a shell variable, and that variable is removed. -Read-only variables may not be unset. -If -.B \-f -is specified, each -.I name -refers to a shell function, and the function definition -is removed. -If the -.B \-n -option is supplied, and \fIname\fP is a variable with the \fInameref\fP -attribute, \fIname\fP will be unset rather than the variable it -references. -\fB\-n\fP has no effect if the \fB\-f\fP option is supplied. -If no options are supplied, each \fIname\fP refers to a variable; if -there is no variable by that name, any function with that name is -unset. -Each unset variable or function is removed from the environment -passed to subsequent commands. -If any of -.SM -.BR COMP_WORDBREAKS , -.SM -.BR RANDOM , -.SM -.BR SECONDS , -.SM -.BR LINENO , -.SM -.BR HISTCMD , -.SM -.BR FUNCNAME , -.SM -.BR GROUPS , -or -.SM -.B DIRSTACK -are unset, they lose their special properties, even if they are -subsequently reset. The exit status is true unless a -.I name -is readonly. -.TP -\fBwait\fP [\fB\-n\fP] [\fIn ...\fP] -Wait for each specified child 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 -in that job's pipeline are waited for. If -.I n -is not given, all currently active child processes -are waited for, and the return status is zero. -If the \fB\-n\fP option is supplied, \fBwait\fP waits for any job to -terminate and returns its exit status. -If -.I n -specifies a non-existent process or job, the return status is -127. Otherwise, the return status is the exit status of the last -process or job waited for. -.\" bash_builtins -.if \n(zZ=1 .ig zZ -.SH "RESTRICTED SHELL" -.\" rbash.1 -.zY -.PP -If -.B bash -is started with the name -.BR rbash , -or the -.B \-r -option is supplied at invocation, -the shell becomes restricted. -A restricted shell is used to -set up an environment more controlled than the standard shell. -It behaves identically to -.B bash -with the exception that the following are disallowed or not performed: -.IP \(bu -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 / -.IP \(bu -specifying a filename containing a -.B / -as an argument to the -.B . -builtin command -.IP \(bu -specifying a filename containing a slash as an argument to the -.B \-p -option to the -.B hash -builtin command -.IP \(bu -importing function definitions from the shell environment at startup -.IP \(bu -parsing the value of -.SM -.B SHELLOPTS -from the shell environment at startup -.IP \(bu -redirecting output using the >, >|, <>, >&, &>, and >> redirection operators -.IP \(bu -using the -.B exec -builtin command to replace the shell with another command -.IP \(bu -adding or deleting builtin commands with the -.B \-f -and -.B \-d -options to the -.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 -.B command -builtin command -.IP \(bu -turning off restricted mode with -\fBset +r\fP or \fBset +o restricted\fP. -.PP -These restrictions are enforced after any startup files are read. -.PP -.ie \n(zY=1 When a command that is found to be a shell script is executed, -.el \{ When a command that is found to be a shell script is executed -(see -.SM -.B "COMMAND EXECUTION" -above), -\} -.B rbash -turns off any restrictions in the shell spawned to execute the -script. -.\" end of rbash.1 -.if \n(zY=1 .ig zY -.SH "SEE ALSO" -.PD 0 -.TP -\fIBash Reference Manual\fP, Brian Fox and Chet Ramey -.TP -\fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey -.TP -\fIThe Gnu History Library\fP, Brian Fox and Chet Ramey -.TP -\fIPortable Operating System Interface (POSIX) Part 2: Shell and Utilities\fP, IEEE -- -http://pubs.opengroup.org/onlinepubs/9699919799/ -.TP -http://tiswww.case.edu/~chet/bash/POSIX -- a description of posix mode -.TP -\fIsh\fP(1), \fIksh\fP(1), \fIcsh\fP(1) -.TP -\fIemacs\fP(1), \fIvi\fP(1) -.TP -\fIreadline\fP(3) -.PD -.SH FILES -.PD 0 -.TP -.FN /bin/bash -The \fBbash\fP executable -.TP -.FN /etc/profile -The systemwide initialization file, executed for login shells -.TP -.FN ~/.bash_profile -The personal initialization file, executed for login shells -.TP -.FN ~/.bashrc -The individual per-interactive-shell startup file -.TP -.FN ~/.bash_logout -The individual login shell cleanup file, executed when a login shell exits -.TP -.FN ~/.inputrc -Individual \fIreadline\fP initialization file -.PD -.SH AUTHORS -Brian Fox, Free Software Foundation -.br -bfox@gnu.org -.PP -Chet Ramey, Case Western Reserve University -.br -chet.ramey@case.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 -.BR bash . -The latest version is always available from -\fIftp://ftp.gnu.org/pub/gnu/bash/\fP. -.PP -Once you have determined that a bug actually exists, use the -.I bashbug -command to submit a bug report. -If you have a fix, you are encouraged to mail that as well! -Suggestions and `philosophical' bug reports may be mailed -to \fIbug-bash@gnu.org\fP or posted to the Usenet -newsgroup -.BR gnu.bash.bug . -.PP -ALL bug reports should include: -.PP -.PD 0 -.TP 20 -The version number of \fBbash\fR -.TP -The hardware and operating system -.TP -The compiler used to compile -.TP -A description of the bug behaviour -.TP -A short script or `recipe' which exercises the bug -.PD -.PP -.I bashbug -inserts the first three items automatically into the template -it provides for filing a bug report. -.PP -Comments and bug reports concerning -this manual page should be directed to -.IR chet.ramey@case.edu . -.SH BUGS -.PP -It's too big and too slow. -.PP -There are some subtle differences between -.B bash -and traditional versions of -.BR sh , -mostly because of the -.SM -.B POSIX -specification. -.PP -Aliases are confusing in some uses. -.PP -Shell builtin commands and functions are not stoppable/restartable. -.PP -Compound commands and command sequences of the form `a ; b ; c' -are not handled gracefully when process suspension is attempted. -When a process is stopped, the shell immediately executes the next -command in the sequence. -It suffices to place the sequence of commands between -parentheses to force it into a subshell, which may be stopped as -a unit. -.PP -Array variables may not (yet) be exported. -.PP -There may be only one active coprocess at a time. -.zZ -.zY |