6 bash - GNU Bourne-Again SHell
8 S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
9 b
\bba
\bas
\bsh
\bh [options] [command_string | file]
11 C
\bCO
\bOP
\bPY
\bYR
\bRI
\bIG
\bGH
\bHT
\bT
12 Bash is Copyright (C) 1989-2013 by the Free Software Foundation, Inc.
14 D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
15 B
\bBa
\bas
\bsh
\bh is an s
\bsh
\bh-compatible command language interpreter that executes
16 commands read from the standard input or from a file. B
\bBa
\bas
\bsh
\bh also incor-
17 porates useful features from the _
\bK_
\bo_
\br_
\bn and _
\bC shells (k
\bks
\bsh
\bh and c
\bcs
\bsh
\bh).
19 B
\bBa
\bas
\bsh
\bh is intended to be a conformant implementation of the Shell and
20 Utilities portion of the IEEE POSIX specification (IEEE Standard
21 1003.1). B
\bBa
\bas
\bsh
\bh can be configured to be POSIX-conformant by default.
23 O
\bOP
\bPT
\bTI
\bIO
\bON
\bNS
\bS
24 All of the single-character shell options documented in the descrip-
25 tion of the s
\bse
\bet
\bt builtin command can be used as options when the shell
26 is invoked. In addition, b
\bba
\bas
\bsh
\bh interprets the following options when it
29 -
\b-c
\bc If the -
\b-c
\bc option is present, then commands are read from the
30 first non-option argument _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b__
\bs_
\bt_
\br_
\bi_
\bn_
\bg. If there are argu-
31 ments after the _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b__
\bs_
\bt_
\br_
\bi_
\bn_
\bg, they are assigned to the
32 positional parameters, starting with $
\b$0
\b0.
33 -
\b-i
\bi If the -
\b-i
\bi option is present, the shell is _
\bi_
\bn_
\bt_
\be_
\br_
\ba_
\bc_
\bt_
\bi_
\bv_
\be.
34 -
\b-l
\bl Make b
\bba
\bas
\bsh
\bh act as if it had been invoked as a login shell (see
35 I
\bIN
\bNV
\bVO
\bOC
\bCA
\bAT
\bTI
\bIO
\bON
\bN below).
36 -
\b-r
\br If the -
\b-r
\br option is present, the shell becomes _
\br_
\be_
\bs_
\bt_
\br_
\bi_
\bc_
\bt_
\be_
\bd
37 (see R
\bRE
\bES
\bST
\bTR
\bRI
\bIC
\bCT
\bTE
\bED
\bD S
\bSH
\bHE
\bEL
\bLL
\bL below).
38 -
\b-s
\bs If the -
\b-s
\bs option is present, or if no arguments remain after
39 option processing, then commands are read from the standard
40 input. This option allows the positional parameters to be
41 set when invoking an interactive shell.
42 -
\b-D
\bD A list of all double-quoted strings preceded by $
\b$ is printed
43 on the standard output. These are the strings that are sub-
44 ject to language translation when the current locale is not C
\bC
45 or P
\bPO
\bOS
\bSI
\bIX
\bX. This implies the -
\b-n
\bn option; no commands will be
47 [
\b[-
\b-+
\b+]
\b]O
\bO [
\b[_
\bs_
\bh_
\bo_
\bp_
\bt_
\b__
\bo_
\bp_
\bt_
\bi_
\bo_
\bn]
\b]
48 _
\bs_
\bh_
\bo_
\bp_
\bt_
\b__
\bo_
\bp_
\bt_
\bi_
\bo_
\bn is one of the shell options accepted by the
49 s
\bsh
\bho
\bop
\bpt
\bt builtin (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). If
50 _
\bs_
\bh_
\bo_
\bp_
\bt_
\b__
\bo_
\bp_
\bt_
\bi_
\bo_
\bn is present, -
\b-O
\bO sets the value of that option; +
\b+O
\bO
51 unsets it. If _
\bs_
\bh_
\bo_
\bp_
\bt_
\b__
\bo_
\bp_
\bt_
\bi_
\bo_
\bn is not supplied, the names and
52 values of the shell options accepted by s
\bsh
\bho
\bop
\bpt
\bt are printed on
53 the standard output. If the invocation option is +
\b+O
\bO, the
54 output is displayed in a format that may be reused as input.
55 -
\b--
\b- A -
\b--
\b- signals the end of options and disables further option
56 processing. Any arguments after the -
\b--
\b- are treated as file-
57 names and arguments. An argument of -
\b- is equivalent to -
\b--
\b-.
59 B
\bBa
\bas
\bsh
\bh also interprets a number of multi-character options. These
60 options must appear on the command line before the single-character
61 options to be recognized.
63 -
\b--
\b-d
\bde
\beb
\bbu
\bug
\bgg
\bge
\ber
\br
64 Arrange for the debugger profile to be executed before the shell
65 starts. Turns on extended debugging mode (see the description
66 of the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg option to the s
\bsh
\bho
\bop
\bpt
\bt builtin below).
67 -
\b--
\b-d
\bdu
\bum
\bmp
\bp-
\b-p
\bpo
\bo-
\b-s
\bst
\btr
\bri
\bin
\bng
\bgs
\bs
68 Equivalent to -
\b-D
\bD, but the output is in the GNU _
\bg_
\be_
\bt_
\bt_
\be_
\bx_
\bt p
\bpo
\bo (por-
69 table object) file format.
70 -
\b--
\b-d
\bdu
\bum
\bmp
\bp-
\b-s
\bst
\btr
\bri
\bin
\bng
\bgs
\bs
71 Equivalent to -
\b-D
\bD.
72 -
\b--
\b-h
\bhe
\bel
\blp
\bp Display a usage message on standard output and exit success-
74 -
\b--
\b-i
\bin
\bni
\bit
\bt-
\b-f
\bfi
\bil
\ble
\be _
\bf_
\bi_
\bl_
\be
75 -
\b--
\b-r
\brc
\bcf
\bfi
\bil
\ble
\be _
\bf_
\bi_
\bl_
\be
76 Execute commands from _
\bf_
\bi_
\bl_
\be instead of the standard personal ini-
77 tialization file _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc if the shell is interactive (see
78 I
\bIN
\bNV
\bVO
\bOC
\bCA
\bAT
\bTI
\bIO
\bON
\bN below).
80 -
\b--
\b-l
\blo
\bog
\bgi
\bin
\bn
81 Equivalent to -
\b-l
\bl.
83 -
\b--
\b-n
\bno
\boe
\bed
\bdi
\bit
\bti
\bin
\bng
\bg
84 Do not use the GNU r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be library to read command lines when
85 the shell is interactive.
87 -
\b--
\b-n
\bno
\bop
\bpr
\bro
\bof
\bfi
\bil
\ble
\be
88 Do not read either the system-wide startup file _
\b/_
\be_
\bt_
\bc_
\b/_
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be or
89 any of the personal initialization files _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be,
90 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bl_
\bo_
\bg_
\bi_
\bn, or _
\b~_
\b/_
\b._
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be. By default, b
\bba
\bas
\bsh
\bh reads these
91 files when it is invoked as a login shell (see I
\bIN
\bNV
\bVO
\bOC
\bCA
\bAT
\bTI
\bIO
\bON
\bN
94 -
\b--
\b-n
\bno
\bor
\brc
\bc Do not read and execute the personal initialization file
95 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc if the shell is interactive. This option is on by
96 default if the shell is invoked as s
\bsh
\bh.
98 -
\b--
\b-p
\bpo
\bos
\bsi
\bix
\bx
99 Change the behavior of b
\bba
\bas
\bsh
\bh where the default operation differs
100 from the POSIX standard to match the standard (_
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be). See
101 S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO below for a reference to a document that details how
102 posix mode affects bash's behavior.
104 -
\b--
\b-r
\bre
\bes
\bst
\btr
\bri
\bic
\bct
\bte
\bed
\bd
105 The shell becomes restricted (see R
\bRE
\bES
\bST
\bTR
\bRI
\bIC
\bCT
\bTE
\bED
\bD S
\bSH
\bHE
\bEL
\bLL
\bL below).
107 -
\b--
\b-v
\bve
\ber
\brb
\bbo
\bos
\bse
\be
108 Equivalent to -
\b-v
\bv.
110 -
\b--
\b-v
\bve
\ber
\brs
\bsi
\bio
\bon
\bn
111 Show version information for this instance of b
\bba
\bas
\bsh
\bh on the stan-
112 dard output and exit successfully.
114 A
\bAR
\bRG
\bGU
\bUM
\bME
\bEN
\bNT
\bTS
\bS
115 If arguments remain after option processing, and neither the -
\b-c
\bc nor the
116 -
\b-s
\bs option has been supplied, the first argument is assumed to be the
117 name of a file containing shell commands. If b
\bba
\bas
\bsh
\bh is invoked in this
118 fashion, $
\b$0
\b0 is set to the name of the file, and the positional parame-
119 ters are set to the remaining arguments. B
\bBa
\bas
\bsh
\bh reads and executes com-
120 mands from this file, then exits. B
\bBa
\bas
\bsh
\bh's exit status is the exit sta-
121 tus of the last command executed in the script. If no commands are
122 executed, the exit status is 0. An attempt is first made to open the
123 file in the current directory, and, if no file is found, then the shell
124 searches the directories in P
\bPA
\bAT
\bTH
\bH for the script.
126 I
\bIN
\bNV
\bVO
\bOC
\bCA
\bAT
\bTI
\bIO
\bON
\bN
127 A _
\bl_
\bo_
\bg_
\bi_
\bn _
\bs_
\bh_
\be_
\bl_
\bl is one whose first character of argument zero is a -
\b-, or
128 one started with the -
\b--
\b-l
\blo
\bog
\bgi
\bin
\bn option.
130 An _
\bi_
\bn_
\bt_
\be_
\br_
\ba_
\bc_
\bt_
\bi_
\bv_
\be shell is one started without non-option arguments and
131 without the -
\b-c
\bc option whose standard input and error are both connected
132 to terminals (as determined by _
\bi_
\bs_
\ba_
\bt_
\bt_
\by(3)), or one started with the -
\b-i
\bi
133 option. P
\bPS
\bS1
\b1 is set and $
\b$-
\b- includes i
\bi if b
\bba
\bas
\bsh
\bh is interactive, allowing
134 a shell script or a startup file to test this state.
136 The following paragraphs describe how b
\bba
\bas
\bsh
\bh executes its startup files.
137 If any of the files exist but cannot be read, b
\bba
\bas
\bsh
\bh reports an error.
138 Tildes are expanded in filenames as described below under T
\bTi
\bil
\bld
\bde
\be E
\bEx
\bxp
\bpa
\ban
\bn-
\b-
139 s
\bsi
\bio
\bon
\bn in the E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN section.
141 When b
\bba
\bas
\bsh
\bh is invoked as an interactive login shell, or as a non-inter-
142 active shell with the -
\b--
\b-l
\blo
\bog
\bgi
\bin
\bn option, it first reads and executes com-
143 mands from the file _
\b/_
\be_
\bt_
\bc_
\b/_
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be, if that file exists. After reading
144 that file, it looks for _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be, _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bl_
\bo_
\bg_
\bi_
\bn, and _
\b~_
\b/_
\b._
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be,
145 in that order, and reads and executes commands from the first one that
146 exists and is readable. The -
\b--
\b-n
\bno
\bop
\bpr
\bro
\bof
\bfi
\bil
\ble
\be option may be used when the
147 shell is started to inhibit this behavior.
149 When a login shell exits, b
\bba
\bas
\bsh
\bh reads and executes commands from the
150 file _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bl_
\bo_
\bg_
\bo_
\bu_
\bt, if it exists.
152 When an interactive shell that is not a login shell is started, b
\bba
\bas
\bsh
\bh
153 reads and executes commands from _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc, if that file exists. This
154 may be inhibited by using the -
\b--
\b-n
\bno
\bor
\brc
\bc option. The -
\b--
\b-r
\brc
\bcf
\bfi
\bil
\ble
\be _
\bf_
\bi_
\bl_
\be option
155 will force b
\bba
\bas
\bsh
\bh to read and execute commands from _
\bf_
\bi_
\bl_
\be instead of
156 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc.
158 When b
\bba
\bas
\bsh
\bh is started non-interactively, to run a shell script, for
159 example, it looks for the variable B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV in the environment, expands
160 its value if it appears there, and uses the expanded value as the name
161 of a file to read and execute. B
\bBa
\bas
\bsh
\bh behaves as if the following com-
163 if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
164 but the value of the P
\bPA
\bAT
\bTH
\bH variable is not used to search for the file-
167 If b
\bba
\bas
\bsh
\bh is invoked with the name s
\bsh
\bh, it tries to mimic the startup
168 behavior of historical versions of s
\bsh
\bh as closely as possible, while
169 conforming to the POSIX standard as well. When invoked as an interac-
170 tive login shell, or a non-interactive shell with the -
\b--
\b-l
\blo
\bog
\bgi
\bin
\bn option,
171 it first attempts to read and execute commands from _
\b/_
\be_
\bt_
\bc_
\b/_
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be and
172 _
\b~_
\b/_
\b._
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be, in that order. The -
\b--
\b-n
\bno
\bop
\bpr
\bro
\bof
\bfi
\bil
\ble
\be option may be used to
173 inhibit this behavior. When invoked as an interactive shell with the
174 name s
\bsh
\bh, b
\bba
\bas
\bsh
\bh looks for the variable E
\bEN
\bNV
\bV, expands its value if it is
175 defined, and uses the expanded value as the name of a file to read and
176 execute. Since a shell invoked as s
\bsh
\bh does not attempt to read and exe-
177 cute commands from any other startup files, the -
\b--
\b-r
\brc
\bcf
\bfi
\bil
\ble
\be option has no
178 effect. A non-interactive shell invoked with the name s
\bsh
\bh does not
179 attempt to read any other startup files. When invoked as s
\bsh
\bh, b
\bba
\bas
\bsh
\bh
180 enters _
\bp_
\bo_
\bs_
\bi_
\bx mode after the startup files are read.
182 When b
\bba
\bas
\bsh
\bh is started in _
\bp_
\bo_
\bs_
\bi_
\bx mode, as with the -
\b--
\b-p
\bpo
\bos
\bsi
\bix
\bx command line
183 option, it follows the POSIX standard for startup files. In this mode,
184 interactive shells expand the E
\bEN
\bNV
\bV variable and commands are read and
185 executed from the file whose name is the expanded value. No other
186 startup files are read.
188 B
\bBa
\bas
\bsh
\bh attempts to determine when it is being run with its standard input
189 connected to a network connection, as when executed by the remote shell
190 daemon, usually _
\br_
\bs_
\bh_
\bd, or the secure shell daemon _
\bs_
\bs_
\bh_
\bd. If b
\bba
\bas
\bsh
\bh deter-
191 mines it is being run in this fashion, it reads and executes commands
192 from _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc, if that file exists and is readable. It will not do
193 this if invoked as s
\bsh
\bh. The -
\b--
\b-n
\bno
\bor
\brc
\bc option may be used to inhibit this
194 behavior, and the -
\b--
\b-r
\brc
\bcf
\bfi
\bil
\ble
\be option may be used to force another file to
195 be read, but neither _
\br_
\bs_
\bh_
\bd nor _
\bs_
\bs_
\bh_
\bd generally invoke the shell with
196 those options or allow them to be specified.
198 If the shell is started with the effective user (group) id not equal to
199 the real user (group) id, and the -
\b-p
\bp option is not supplied, no startup
200 files are read, shell functions are not inherited from the environment,
201 the S
\bSH
\bHE
\bEL
\bLL
\bLO
\bOP
\bPT
\bTS
\bS, B
\bBA
\bAS
\bSH
\bHO
\bOP
\bPT
\bTS
\bS, C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH, and G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE variables, if they
202 appear in the environment, are ignored, and the effective user id is
203 set to the real user id. If the -
\b-p
\bp option is supplied at invocation,
204 the startup behavior is the same, but the effective user id is not
207 D
\bDE
\bEF
\bFI
\bIN
\bNI
\bIT
\bTI
\bIO
\bON
\bNS
\bS
208 The following definitions are used throughout the rest of this docu-
210 b
\bbl
\bla
\ban
\bnk
\bk A space or tab.
211 w
\bwo
\bor
\brd
\bd A sequence of characters considered as a single unit by the
212 shell. Also known as a t
\bto
\bok
\bke
\ben
\bn.
213 n
\bna
\bam
\bme
\be A _
\bw_
\bo_
\br_
\bd consisting only of alphanumeric characters and under-
214 scores, and beginning with an alphabetic character or an under-
215 score. Also referred to as an i
\bid
\bde
\ben
\bnt
\bti
\bif
\bfi
\bie
\ber
\br.
216 m
\bme
\bet
\bta
\bac
\bch
\bha
\bar
\bra
\bac
\bct
\bte
\ber
\br
217 A character that, when unquoted, separates words. One of the
219 |
\b| &
\b& ;
\b; (
\b( )
\b) <
\b< >
\b> s
\bsp
\bpa
\bac
\bce
\be t
\bta
\bab
\bb
220 c
\bco
\bon
\bnt
\btr
\bro
\bol
\bl o
\bop
\bpe
\ber
\bra
\bat
\bto
\bor
\br
221 A _
\bt_
\bo_
\bk_
\be_
\bn that performs a control function. It is one of the fol-
223 |
\b||
\b| &
\b& &
\b&&
\b& ;
\b; ;
\b;;
\b; (
\b( )
\b) |
\b| |
\b|&
\b& <
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b>
225 R
\bRE
\bES
\bSE
\bER
\bRV
\bVE
\bED
\bD W
\bWO
\bOR
\bRD
\bDS
\bS
226 _
\bR_
\be_
\bs_
\be_
\br_
\bv_
\be_
\bd _
\bw_
\bo_
\br_
\bd_
\bs are words that have a special meaning to the shell. The
227 following words are recognized as reserved when unquoted and either the
228 first word of a simple command (see S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR below) or the third
229 word of a c
\bca
\bas
\bse
\be or f
\bfo
\bor
\br command:
231 !
\b! c
\bca
\bas
\bse
\be c
\bco
\bop
\bpr
\bro
\boc
\bc d
\bdo
\bo d
\bdo
\bon
\bne
\be e
\bel
\bli
\bif
\bf e
\bel
\bls
\bse
\be e
\bes
\bsa
\bac
\bc f
\bfi
\bi f
\bfo
\bor
\br f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn i
\bif
\bf i
\bin
\bn s
\bse
\bel
\ble
\bec
\bct
\bt
232 t
\bth
\bhe
\ben
\bn u
\bun
\bnt
\bti
\bil
\bl w
\bwh
\bhi
\bil
\ble
\be {
\b{ }
\b} t
\bti
\bim
\bme
\be [
\b[[
\b[ ]
\b]]
\b]
234 S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR
235 S
\bSi
\bim
\bmp
\bpl
\ble
\be C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs
236 A _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is a sequence of optional variable assignments fol-
237 lowed by b
\bbl
\bla
\ban
\bnk
\bk-separated words and redirections, and terminated by a
238 _
\bc_
\bo_
\bn_
\bt_
\br_
\bo_
\bl _
\bo_
\bp_
\be_
\br_
\ba_
\bt_
\bo_
\br. The first word specifies the command to be executed,
239 and is passed as argument zero. The remaining words are passed as
240 arguments to the invoked command.
242 The return value of a _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is its exit status, or 128+_
\bn if
243 the command is terminated by signal _
\bn.
245 P
\bPi
\bip
\bpe
\bel
\bli
\bin
\bne
\bes
\bs
246 A _
\bp_
\bi_
\bp_
\be_
\bl_
\bi_
\bn_
\be is a sequence of one or more commands separated by one of
247 the control operators |
\b| or |
\b|&
\b&. The format for a pipeline is:
249 [t
\bti
\bim
\bme
\be [-
\b-p
\bp]] [ ! ] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [ [|
\b|||
\b|&
\b&] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2 ... ]
251 The standard output of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is connected via a pipe to the standard
252 input of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2. This connection is performed before any redirec-
253 tions specified by the command (see R
\bRE
\bED
\bDI
\bIR
\bRE
\bEC
\bCT
\bTI
\bIO
\bON
\bN below). If |
\b|&
\b& is used,
254 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd's standard error, in addition to its standard output, is con-
255 nected to _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2's standard input through the pipe; it is shorthand
256 for 2
\b2>
\b>&
\b&1
\b1 |
\b|. This implicit redirection of the standard error to the
257 standard output is performed after any redirections specified by the
260 The return status of a pipeline is the exit status of the last command,
261 unless the p
\bpi
\bip
\bpe
\bef
\bfa
\bai
\bil
\bl option is enabled. If p
\bpi
\bip
\bpe
\bef
\bfa
\bai
\bil
\bl is enabled, the
262 pipeline's return status is the value of the last (rightmost) command
263 to exit with a non-zero status, or zero if all commands exit success-
264 fully. If the reserved word !
\b! precedes a pipeline, the exit status of
265 that pipeline is the logical negation of the exit status as described
266 above. The shell waits for all commands in the pipeline to terminate
267 before returning a value.
269 If the t
\bti
\bim
\bme
\be reserved word precedes a pipeline, the elapsed as well as
270 user and system time consumed by its execution are reported when the
271 pipeline terminates. The -
\b-p
\bp option changes the output format to that
272 specified by POSIX. When the shell is in _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be, it does not rec-
273 ognize t
\bti
\bim
\bme
\be as a reserved word if the next token begins with a `-'.
274 The T
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT variable may be set to a format string that specifies
275 how the timing information should be displayed; see the description of
276 T
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT under S
\bSh
\bhe
\bel
\bll
\bl V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs below.
278 When the shell is in _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be, t
\bti
\bim
\bme
\be may be followed by a newline. In
279 this case, the shell displays the total user and system time consumed
280 by the shell and its children. The T
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT variable may be used to
281 specify the format of the time information.
283 Each command in a pipeline is executed as a separate process (i.e., in
287 A _
\bl_
\bi_
\bs_
\bt is a sequence of one or more pipelines separated by one of the
288 operators ;
\b;, &
\b&, &
\b&&
\b&, or |
\b||
\b|, and optionally terminated by one of ;
\b;, &
\b&, or
289 <
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b>.
291 Of these list operators, &
\b&&
\b& and |
\b||
\b| have equal precedence, followed by ;
\b;
292 and &
\b&, which have equal precedence.
294 A sequence of one or more newlines may appear in a _
\bl_
\bi_
\bs_
\bt instead of a
295 semicolon to delimit commands.
297 If a command is terminated by the control operator &
\b&, the shell exe-
298 cutes the command in the _
\bb_
\ba_
\bc_
\bk_
\bg_
\br_
\bo_
\bu_
\bn_
\bd in a subshell. The shell does not
299 wait for the command to finish, and the return status is 0. Commands
300 separated by a ;
\b; are executed sequentially; the shell waits for each
301 command to terminate in turn. The return status is the exit status of
302 the last command executed.
304 AND and OR lists are sequences of one of more pipelines separated by
305 the &
\b&&
\b& and |
\b||
\b| control operators, respectively. AND and OR lists are
306 executed with left associativity. An AND list has the form
308 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b1 &
\b&&
\b& _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2
310 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2 is executed if, and only if, _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b1 returns an exit status
313 An OR list has the form
315 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b1 |
\b||
\b| _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2
318 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b2 is executed if and only if _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd_
\b1 returns a non-zero exit
319 status. The return status of AND and OR lists is the exit status of
320 the last command executed in the list.
322 C
\bCo
\bom
\bmp
\bpo
\bou
\bun
\bnd
\bd C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs
323 A _
\bc_
\bo_
\bm_
\bp_
\bo_
\bu_
\bn_
\bd _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is one of the following. In most cases a _
\bl_
\bi_
\bs_
\bt in a
324 command's description may be separated from the rest of the command by
325 one or more newlines, and may be followed by a newline in place of a
328 (_
\bl_
\bi_
\bs_
\bt) _
\bl_
\bi_
\bs_
\bt is executed in a subshell environment (see C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD E
\bEX
\bXE
\bEC
\bCU
\bU-
\b-
329 T
\bTI
\bIO
\bON
\bN E
\bEN
\bNV
\bVI
\bIR
\bRO
\bON
\bNM
\bME
\bEN
\bNT
\bT below). Variable assignments and builtin com-
330 mands that affect the shell's environment do not remain in
331 effect after the command completes. The return status is the
332 exit status of _
\bl_
\bi_
\bs_
\bt.
334 { _
\bl_
\bi_
\bs_
\bt; }
335 _
\bl_
\bi_
\bs_
\bt is simply executed in the current shell environment. _
\bl_
\bi_
\bs_
\bt
336 must be terminated with a newline or semicolon. This is known
337 as a _
\bg_
\br_
\bo_
\bu_
\bp _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd. The return status is the exit status of
338 _
\bl_
\bi_
\bs_
\bt. Note that unlike the metacharacters (
\b( and )
\b), {
\b{ and }
\b} are
339 _
\br_
\be_
\bs_
\be_
\br_
\bv_
\be_
\bd _
\bw_
\bo_
\br_
\bd_
\bs and must occur where a reserved word is permitted
340 to be recognized. Since they do not cause a word break, they
341 must be separated from _
\bl_
\bi_
\bs_
\bt by whitespace or another shell
344 ((_
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn))
345 The _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn is evaluated according to the rules described
346 below under A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN. If the value of the expres-
347 sion is non-zero, the return status is 0; otherwise the return
348 status is 1. This is exactly equivalent to l
\ble
\bet
\bt "
\b"_
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn"
\b".
350 [
\b[[
\b[ _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn ]
\b]]
\b]
351 Return a status of 0 or 1 depending on the evaluation of the
352 conditional expression _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn. Expressions are composed of
353 the primaries described below under C
\bCO
\bON
\bND
\bDI
\bIT
\bTI
\bIO
\bON
\bNA
\bAL
\bL E
\bEX
\bXP
\bPR
\bRE
\bES
\bSS
\bSI
\bIO
\bON
\bNS
\bS.
354 Word splitting and pathname expansion are not performed on the
355 words between the [
\b[[
\b[ and ]
\b]]
\b]; tilde expansion, parameter and
356 variable expansion, arithmetic expansion, command substitution,
357 process substitution, and quote removal are performed. Condi-
358 tional operators such as -
\b-f
\bf must be unquoted to be recognized as
361 When used with [
\b[[
\b[, the <
\b< and >
\b> operators sort lexicographically
362 using the current locale.
364 When the =
\b==
\b= and !
\b!=
\b= operators are used, the string to the right
365 of the operator is considered a pattern and matched according to
366 the rules described below under P
\bPa
\bat
\btt
\bte
\ber
\brn
\bn M
\bMa
\bat
\btc
\bch
\bhi
\bin
\bng
\bg, as if the e
\bex
\bxt
\bt-
\b-
367 g
\bgl
\blo
\bob
\bb shell option were enabled. The =
\b= operator is equivalent to
368 =
\b==
\b=. If the shell option n
\bno
\boc
\bca
\bas
\bse
\bem
\bma
\bat
\btc
\bch
\bh is enabled, the match is
369 performed without regard to the case of alphabetic characters.
370 The return value is 0 if the string matches (=
\b==
\b=) or does not
371 match (!
\b!=
\b=) the pattern, and 1 otherwise. Any part of the pat-
372 tern may be quoted to force the quoted portion to be matched as
375 An additional binary operator, =
\b=~
\b~, is available, with the same
376 precedence as =
\b==
\b= and !
\b!=
\b=. When it is used, the string to the
377 right of the operator is considered an extended regular expres-
378 sion and matched accordingly (as in _
\br_
\be_
\bg_
\be_
\bx(3)). The return value
379 is 0 if the string matches the pattern, and 1 otherwise. If the
380 regular expression is syntactically incorrect, the conditional
381 expression's return value is 2. If the shell option n
\bno
\boc
\bca
\bas
\bse
\bem
\bma
\bat
\btc
\bch
\bh
382 is enabled, the match is performed without regard to the case of
383 alphabetic characters. Any part of the pattern may be quoted to
384 force the quoted portion to be matched as a string. Bracket
385 expressions in regular expressions must be treated carefully,
386 since normal quoting characters lose their meanings between
387 brackets. If the pattern is stored in a shell variable, quoting
388 the variable expansion forces the entire pattern to be matched
389 as a string. Substrings matched by parenthesized subexpressions
390 within the regular expression are saved in the array variable
391 B
\bBA
\bAS
\bSH
\bH_
\b_R
\bRE
\bEM
\bMA
\bAT
\bTC
\bCH
\bH. The element of B
\bBA
\bAS
\bSH
\bH_
\b_R
\bRE
\bEM
\bMA
\bAT
\bTC
\bCH
\bH with index 0 is the
392 portion of the string matching the entire regular expression.
393 The element of B
\bBA
\bAS
\bSH
\bH_
\b_R
\bRE
\bEM
\bMA
\bAT
\bTC
\bCH
\bH with index _
\bn is the portion of the
394 string matching the _
\bnth parenthesized subexpression.
396 Expressions may be combined using the following operators,
397 listed in decreasing order of precedence:
399 (
\b( _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn )
\b)
400 Returns the value of _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn. This may be used to
401 override the normal precedence of operators.
402 !
\b! _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn
403 True if _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn is false.
404 _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b1 &
\b&&
\b& _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b2
405 True if both _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b1 and _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b2 are true.
406 _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b1 |
\b||
\b| _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b2
407 True if either _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b1 or _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b2 is true.
409 The &
\b&&
\b& and |
\b||
\b| operators do not evaluate _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b2 if the value
410 of _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn_
\b1 is sufficient to determine the return value of
411 the entire conditional expression.
413 f
\bfo
\bor
\br _
\bn_
\ba_
\bm_
\be [ [ i
\bin
\bn [ _
\bw_
\bo_
\br_
\bd _
\b._
\b._
\b. ] ] ; ] d
\bdo
\bo _
\bl_
\bi_
\bs_
\bt ; d
\bdo
\bon
\bne
\be
414 The list of words following i
\bin
\bn is expanded, generating a list of
415 items. The variable _
\bn_
\ba_
\bm_
\be is set to each element of this list in
416 turn, and _
\bl_
\bi_
\bs_
\bt is executed each time. If the i
\bin
\bn _
\bw_
\bo_
\br_
\bd is omit-
417 ted, the f
\bfo
\bor
\br command executes _
\bl_
\bi_
\bs_
\bt once for each positional
418 parameter that is set (see P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS below). The return status
419 is the exit status of the last command that executes. If the
420 expansion of the items following i
\bin
\bn results in an empty list, no
421 commands are executed, and the return status is 0.
423 f
\bfo
\bor
\br (( _
\be_
\bx_
\bp_
\br_
\b1 ; _
\be_
\bx_
\bp_
\br_
\b2 ; _
\be_
\bx_
\bp_
\br_
\b3 )) ; d
\bdo
\bo _
\bl_
\bi_
\bs_
\bt ; d
\bdo
\bon
\bne
\be
424 First, the arithmetic expression _
\be_
\bx_
\bp_
\br_
\b1 is evaluated according to
425 the rules described below under A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN. The
426 arithmetic expression _
\be_
\bx_
\bp_
\br_
\b2 is then evaluated repeatedly until
427 it evaluates to zero. Each time _
\be_
\bx_
\bp_
\br_
\b2 evaluates to a non-zero
428 value, _
\bl_
\bi_
\bs_
\bt is executed and the arithmetic expression _
\be_
\bx_
\bp_
\br_
\b3 is
429 evaluated. If any expression is omitted, it behaves as if it
430 evaluates to 1. The return value is the exit status of the last
431 command in _
\bl_
\bi_
\bs_
\bt that is executed, or false if any of the expres-
434 s
\bse
\bel
\ble
\bec
\bct
\bt _
\bn_
\ba_
\bm_
\be [ i
\bin
\bn _
\bw_
\bo_
\br_
\bd ] ; d
\bdo
\bo _
\bl_
\bi_
\bs_
\bt ; d
\bdo
\bon
\bne
\be
435 The list of words following i
\bin
\bn is expanded, generating a list of
436 items. The set of expanded words is printed on the standard
437 error, each preceded by a number. If the i
\bin
\bn _
\bw_
\bo_
\br_
\bd is omitted,
438 the positional parameters are printed (see P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS below).
439 The P
\bPS
\bS3
\b3 prompt is then displayed and a line read from the stan-
440 dard input. If the line consists of a number corresponding to
441 one of the displayed words, then the value of _
\bn_
\ba_
\bm_
\be is set to
442 that word. If the line is empty, the words and prompt are dis-
443 played again. If EOF is read, the command completes. Any other
444 value read causes _
\bn_
\ba_
\bm_
\be to be set to null. The line read is
445 saved in the variable R
\bRE
\bEP
\bPL
\bLY
\bY. The _
\bl_
\bi_
\bs_
\bt is executed after each
446 selection until a b
\bbr
\bre
\bea
\bak
\bk command is executed. The exit status of
447 s
\bse
\bel
\ble
\bec
\bct
\bt is the exit status of the last command executed in _
\bl_
\bi_
\bs_
\bt,
448 or zero if no commands were executed.
450 c
\bca
\bas
\bse
\be _
\bw_
\bo_
\br_
\bd i
\bin
\bn [ [(] _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn [ |
\b| _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn ] ... ) _
\bl_
\bi_
\bs_
\bt ;; ] ... e
\bes
\bsa
\bac
\bc
451 A c
\bca
\bas
\bse
\be command first expands _
\bw_
\bo_
\br_
\bd, and tries to match it against
452 each _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn in turn, using the same matching rules as for path-
453 name expansion (see P
\bPa
\bat
\bth
\bhn
\bna
\bam
\bme
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn below). The _
\bw_
\bo_
\br_
\bd is
454 expanded using tilde expansion, parameter and variable expan-
455 sion, arithmetic substitution, command substitution, process
456 substitution and quote removal. Each _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn examined is
457 expanded using tilde expansion, parameter and variable expan-
458 sion, arithmetic substitution, command substitution, and process
459 substitution. If the shell option n
\bno
\boc
\bca
\bas
\bse
\bem
\bma
\bat
\btc
\bch
\bh is enabled, the
460 match is performed without regard to the case of alphabetic
461 characters. When a match is found, the corresponding _
\bl_
\bi_
\bs_
\bt is
462 executed. If the ;
\b;;
\b; operator is used, no subsequent matches are
463 attempted after the first pattern match. Using ;
\b;&
\b& in place of
464 ;
\b;;
\b; causes execution to continue with the _
\bl_
\bi_
\bs_
\bt associated with
465 the next set of patterns. Using ;
\b;;
\b;&
\b& in place of ;
\b;;
\b; causes the
466 shell to test the next pattern list in the statement, if any,
467 and execute any associated _
\bl_
\bi_
\bs_
\bt on a successful match. The exit
468 status is zero if no pattern matches. Otherwise, it is the exit
469 status of the last command executed in _
\bl_
\bi_
\bs_
\bt.
471 i
\bif
\bf _
\bl_
\bi_
\bs_
\bt; t
\bth
\bhe
\ben
\bn _
\bl_
\bi_
\bs_
\bt; [ e
\bel
\bli
\bif
\bf _
\bl_
\bi_
\bs_
\bt; t
\bth
\bhe
\ben
\bn _
\bl_
\bi_
\bs_
\bt; ] ... [ e
\bel
\bls
\bse
\be _
\bl_
\bi_
\bs_
\bt; ] f
\bfi
\bi
472 The i
\bif
\bf _
\bl_
\bi_
\bs_
\bt is executed. If its exit status is zero, the t
\bth
\bhe
\ben
\bn
473 _
\bl_
\bi_
\bs_
\bt is executed. Otherwise, each e
\bel
\bli
\bif
\bf _
\bl_
\bi_
\bs_
\bt is executed in
474 turn, and if its exit status is zero, the corresponding t
\bth
\bhe
\ben
\bn
475 _
\bl_
\bi_
\bs_
\bt is executed and the command completes. Otherwise, the e
\bel
\bls
\bse
\be
476 _
\bl_
\bi_
\bs_
\bt is executed, if present. The exit status is the exit sta-
477 tus of the last command executed, or zero if no condition tested
480 w
\bwh
\bhi
\bil
\ble
\be _
\bl_
\bi_
\bs_
\bt_
\b-_
\b1; d
\bdo
\bo _
\bl_
\bi_
\bs_
\bt_
\b-_
\b2; d
\bdo
\bon
\bne
\be
481 u
\bun
\bnt
\bti
\bil
\bl _
\bl_
\bi_
\bs_
\bt_
\b-_
\b1; d
\bdo
\bo _
\bl_
\bi_
\bs_
\bt_
\b-_
\b2; d
\bdo
\bon
\bne
\be
482 The w
\bwh
\bhi
\bil
\ble
\be command continuously executes the list _
\bl_
\bi_
\bs_
\bt_
\b-_
\b2 as long
483 as the last command in the list _
\bl_
\bi_
\bs_
\bt_
\b-_
\b1 returns an exit status of
484 zero. The u
\bun
\bnt
\bti
\bil
\bl command is identical to the w
\bwh
\bhi
\bil
\ble
\be command,
485 except that the test is negated; _
\bl_
\bi_
\bs_
\bt_
\b-_
\b2 is executed as long as
486 the last command in _
\bl_
\bi_
\bs_
\bt_
\b-_
\b1 returns a non-zero exit status. The
487 exit status of the w
\bwh
\bhi
\bil
\ble
\be and u
\bun
\bnt
\bti
\bil
\bl commands is the exit status
488 of the last command executed in _
\bl_
\bi_
\bs_
\bt_
\b-_
\b2, or zero if none was exe-
491 C
\bCo
\bop
\bpr
\bro
\boc
\bce
\bes
\bss
\bse
\bes
\bs
492 A _
\bc_
\bo_
\bp_
\br_
\bo_
\bc_
\be_
\bs_
\bs is a shell command preceded by the c
\bco
\bop
\bpr
\bro
\boc
\bc reserved word. A
493 coprocess is executed asynchronously in a subshell, as if the command
494 had been terminated with the &
\b& control operator, with a two-way pipe
495 established between the executing shell and the coprocess.
497 The format for a coprocess is:
499 c
\bco
\bop
\bpr
\bro
\boc
\bc [_
\bN_
\bA_
\bM_
\bE] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\br_
\be_
\bd_
\bi_
\br_
\be_
\bc_
\bt_
\bi_
\bo_
\bn_
\bs]
501 This creates a coprocess named _
\bN_
\bA_
\bM_
\bE. If _
\bN_
\bA_
\bM_
\bE is not supplied, the
502 default name is C
\bCO
\bOP
\bPR
\bRO
\bOC
\bC. _
\bN_
\bA_
\bM_
\bE must not be supplied if _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is a _
\bs_
\bi_
\bm_
\b-
503 _
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd (see above); otherwise, it is interpreted as the first word
504 of the simple command. When the coprocess is executed, the shell cre-
505 ates an array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) named _
\bN_
\bA_
\bM_
\bE in the context of
506 the executing shell. The standard output of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is connected via a
507 pipe to a file descriptor in the executing shell, and that file
508 descriptor is assigned to _
\bN_
\bA_
\bM_
\bE[0]. The standard input of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is
509 connected via a pipe to a file descriptor in the executing shell, and
510 that file descriptor is assigned to _
\bN_
\bA_
\bM_
\bE[1]. This pipe is established
511 before any redirections specified by the command (see R
\bRE
\bED
\bDI
\bIR
\bRE
\bEC
\bCT
\bTI
\bIO
\bON
\bN
512 below). The file descriptors can be utilized as arguments to shell
513 commands and redirections using standard word expansions. The file
514 descriptors are not available in subshells. The process ID of the
515 shell spawned to execute the coprocess is available as the value of the
516 variable _
\bN_
\bA_
\bM_
\bE_PID. The w
\bwa
\bai
\bit
\bt builtin command may be used to wait for
517 the coprocess to terminate.
519 Since the coprocess is created as an asynchronous command, the c
\bco
\bop
\bpr
\bro
\boc
\bc
520 command always returns success. The return status of a coprocess is
521 the exit status of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd.
523 S
\bSh
\bhe
\bel
\bll
\bl F
\bFu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn D
\bDe
\bef
\bfi
\bin
\bni
\bit
\bti
\bio
\bon
\bns
\bs
524 A shell function is an object that is called like a simple command and
525 executes a compound command with a new set of positional parameters.
526 Shell functions are declared as follows:
528 _
\bn_
\ba_
\bm_
\be () _
\bc_
\bo_
\bm_
\bp_
\bo_
\bu_
\bn_
\bd_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\br_
\be_
\bd_
\bi_
\br_
\be_
\bc_
\bt_
\bi_
\bo_
\bn]
529 f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn _
\bn_
\ba_
\bm_
\be [()] _
\bc_
\bo_
\bm_
\bp_
\bo_
\bu_
\bn_
\bd_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\br_
\be_
\bd_
\bi_
\br_
\be_
\bc_
\bt_
\bi_
\bo_
\bn]
530 This defines a function named _
\bn_
\ba_
\bm_
\be. The reserved word f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn
531 is optional. If the f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn reserved word is supplied, the
532 parentheses are optional. The _
\bb_
\bo_
\bd_
\by of the function is the com-
533 pound command _
\bc_
\bo_
\bm_
\bp_
\bo_
\bu_
\bn_
\bd_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd (see C
\bCo
\bom
\bmp
\bpo
\bou
\bun
\bnd
\bd C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs above).
534 That command is usually a _
\bl_
\bi_
\bs_
\bt of commands between { and }, but
535 may be any command listed under C
\bCo
\bom
\bmp
\bpo
\bou
\bun
\bnd
\bd C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs above. _
\bc_
\bo_
\bm_
\b-
536 _
\bp_
\bo_
\bu_
\bn_
\bd_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is executed whenever _
\bn_
\ba_
\bm_
\be is specified as the name
537 of a simple command. When in _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be, _
\bn_
\ba_
\bm_
\be may not be the
538 name of one of the POSIX _
\bs_
\bp_
\be_
\bc_
\bi_
\ba_
\bl _
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn_
\bs. Any redirections
539 (see R
\bRE
\bED
\bDI
\bIR
\bRE
\bEC
\bCT
\bTI
\bIO
\bON
\bN below) specified when a function is defined are
540 performed when the function is executed. The exit status of a
541 function definition is zero unless a syntax error occurs or a
542 readonly function with the same name already exists. When exe-
543 cuted, the exit status of a function is the exit status of the
544 last command executed in the body. (See F
\bFU
\bUN
\bNC
\bCT
\bTI
\bIO
\bON
\bNS
\bS below.)
546 C
\bCO
\bOM
\bMM
\bME
\bEN
\bNT
\bTS
\bS
547 In a non-interactive shell, or an interactive shell in which the i
\bin
\bnt
\bte
\ber
\br-
\b-
548 a
\bac
\bct
\bti
\biv
\bve
\be_
\b_c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bts
\bs option to the s
\bsh
\bho
\bop
\bpt
\bt builtin is enabled (see S
\bSH
\bHE
\bEL
\bLL
\bL
549 B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below), a word beginning with #
\b# causes that word and
550 all remaining characters on that line to be ignored. An interactive
551 shell without the i
\bin
\bnt
\bte
\ber
\bra
\bac
\bct
\bti
\biv
\bve
\be_
\b_c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bts
\bs option enabled does not allow
552 comments. The i
\bin
\bnt
\bte
\ber
\bra
\bac
\bct
\bti
\biv
\bve
\be_
\b_c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bts
\bs option is on by default in interac-
555 Q
\bQU
\bUO
\bOT
\bTI
\bIN
\bNG
\bG
556 _
\bQ_
\bu_
\bo_
\bt_
\bi_
\bn_
\bg is used to remove the special meaning of certain characters or
557 words to the shell. Quoting can be used to disable special treatment
558 for special characters, to prevent reserved words from being recognized
559 as such, and to prevent parameter expansion.
561 Each of the _
\bm_
\be_
\bt_
\ba_
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br_
\bs listed above under D
\bDE
\bEF
\bFI
\bIN
\bNI
\bIT
\bTI
\bIO
\bON
\bNS
\bS has special
562 meaning to the shell and must be quoted if it is to represent itself.
564 When the command history expansion facilities are being used (see H
\bHI
\bIS
\bS-
\b-
565 T
\bTO
\bOR
\bRY
\bY E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below), the _
\bh_
\bi_
\bs_
\bt_
\bo_
\br_
\by _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn character, usually !
\b!, must
566 be quoted to prevent history expansion.
568 There are three quoting mechanisms: the _
\be_
\bs_
\bc_
\ba_
\bp_
\be _
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br, single
569 quotes, and double quotes.
571 A non-quoted backslash (\
\b\) is the _
\be_
\bs_
\bc_
\ba_
\bp_
\be _
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br. It preserves the
572 literal value of the next character that follows, with the exception of
573 <newline>. If a \
\b\<newline> pair appears, and the backslash is not
574 itself quoted, the \
\b\<newline> is treated as a line continuation (that
575 is, it is removed from the input stream and effectively ignored).
577 Enclosing characters in single quotes preserves the literal value of
578 each character within the quotes. A single quote may not occur between
579 single quotes, even when preceded by a backslash.
581 Enclosing characters in double quotes preserves the literal value of
582 all characters within the quotes, with the exception of $
\b$, `
\b`, \
\b\, and,
583 when history expansion is enabled, !
\b!. The characters $
\b$ and `
\b` retain
584 their special meaning within double quotes. The backslash retains its
585 special meaning only when followed by one of the following characters:
586 $
\b$, `
\b`, "
\b", \
\b\, or <
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b>. A double quote may be quoted within double
587 quotes by preceding it with a backslash. If enabled, history expansion
588 will be performed unless an !
\b! appearing in double quotes is escaped
589 using a backslash. The backslash preceding the !
\b! is not removed.
591 The special parameters *
\b* and @
\b@ have special meaning when in double
592 quotes (see P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS below).
594 Words of the form $
\b$'_
\bs_
\bt_
\br_
\bi_
\bn_
\bg' are treated specially. The word expands to
595 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg, with backslash-escaped characters replaced as specified by the
596 ANSI C standard. Backslash escape sequences, if present, are decoded
598 \
\b\a
\ba alert (bell)
601 \
\b\E
\bE an escape character
604 \
\b\r
\br carriage return
605 \
\b\t
\bt horizontal tab
606 \
\b\v
\bv vertical tab
608 \
\b\'
\b' single quote
609 \
\b\"
\b" double quote
610 \
\b\_
\bn_
\bn_
\bn the eight-bit character whose value is the octal value
611 _
\bn_
\bn_
\bn (one to three digits)
612 \
\b\x
\bx_
\bH_
\bH the eight-bit character whose value is the hexadecimal
613 value _
\bH_
\bH (one or two hex digits)
614 \
\b\u
\bu_
\bH_
\bH_
\bH_
\bH the Unicode (ISO/IEC 10646) character whose value is the
615 hexadecimal value _
\bH_
\bH_
\bH_
\bH (one to four hex digits)
616 \
\b\U
\bU_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH
617 the Unicode (ISO/IEC 10646) character whose value is the
618 hexadecimal value _
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH (one to eight hex digits)
619 \
\b\c
\bc_
\bx a control-_
\bx character
621 The expanded result is single-quoted, as if the dollar sign had not
624 A double-quoted string preceded by a dollar sign ($
\b$"_
\bs_
\bt_
\br_
\bi_
\bn_
\bg") will cause
625 the string to be translated according to the current locale. If the
626 current locale is C
\bC or P
\bPO
\bOS
\bSI
\bIX
\bX, the dollar sign is ignored. If the
627 string is translated and replaced, the replacement is double-quoted.
629 P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS
630 A _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is an entity that stores values. It can be a _
\bn_
\ba_
\bm_
\be, a num-
631 ber, or one of the special characters listed below under S
\bSp
\bpe
\bec
\bci
\bia
\bal
\bl P
\bPa
\bar
\bra
\bam
\bm-
\b-
632 e
\bet
\bte
\ber
\brs
\bs. A _
\bv_
\ba_
\br_
\bi_
\ba_
\bb_
\bl_
\be is a parameter denoted by a _
\bn_
\ba_
\bm_
\be. A variable has a
633 _
\bv_
\ba_
\bl_
\bu_
\be and zero or more _
\ba_
\bt_
\bt_
\br_
\bi_
\bb_
\bu_
\bt_
\be_
\bs. Attributes are assigned using the
634 d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin command (see d
\bde
\bec
\bcl
\bla
\bar
\bre
\be below in S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS).
636 A parameter is set if it has been assigned a value. The null string is
637 a valid value. Once a variable is set, it may be unset only by using
638 the u
\bun
\bns
\bse
\bet
\bt builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
640 A _
\bv_
\ba_
\br_
\bi_
\ba_
\bb_
\bl_
\be may be assigned to by a statement of the form
642 _
\bn_
\ba_
\bm_
\be=[_
\bv_
\ba_
\bl_
\bu_
\be]
644 If _
\bv_
\ba_
\bl_
\bu_
\be is not given, the variable is assigned the null string. All
645 _
\bv_
\ba_
\bl_
\bu_
\be_
\bs undergo tilde expansion, parameter and variable expansion, com-
646 mand substitution, arithmetic expansion, and quote removal (see E
\bEX
\bXP
\bPA
\bAN
\bN-
\b-
647 S
\bSI
\bIO
\bON
\bN below). If the variable has its i
\bin
\bnt
\bte
\beg
\bge
\ber
\br attribute set, then _
\bv_
\ba_
\bl_
\bu_
\be
648 is evaluated as an arithmetic expression even if the $((...)) expansion
649 is not used (see A
\bAr
\bri
\bit
\bth
\bhm
\bme
\bet
\bti
\bic
\bc E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn below). Word splitting is not
650 performed, with the exception of "
\b"$
\b$@
\b@"
\b" as explained below under S
\bSp
\bpe
\bec
\bci
\bia
\bal
\bl
651 P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\brs
\bs. Pathname expansion is not performed. Assignment state-
652 ments may also appear as arguments to the a
\bal
\bli
\bia
\bas
\bs, d
\bde
\bec
\bcl
\bla
\bar
\bre
\be, t
\bty
\byp
\bpe
\bes
\bse
\bet
\bt,
653 e
\bex
\bxp
\bpo
\bor
\brt
\bt, r
\bre
\bea
\bad
\bdo
\bon
\bnl
\bly
\by, and l
\blo
\boc
\bca
\bal
\bl builtin commands. When in _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be,
654 these builtins may appear in a command after one or more instances of
655 the c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd builtin and retain these assignment statement properties.
657 In the context where an assignment statement is assigning a value to a
658 shell variable or array index, the += operator can be used to append to
659 or add to the variable's previous value. When += is applied to a vari-
660 able for which the _
\bi_
\bn_
\bt_
\be_
\bg_
\be_
\br attribute has been set, _
\bv_
\ba_
\bl_
\bu_
\be is evaluated
661 as an arithmetic expression and added to the variable's current value,
662 which is also evaluated. When += is applied to an array variable using
663 compound assignment (see A
\bAr
\brr
\bra
\bay
\bys
\bs below), the variable's value is not
664 unset (as it is when using =), and new values are appended to the array
665 beginning at one greater than the array's maximum index (for indexed
666 arrays) or added as additional key-value pairs in an associative array.
667 When applied to a string-valued variable, _
\bv_
\ba_
\bl_
\bu_
\be is expanded and
668 appended to the variable's value.
670 A variable can be assigned the _
\bn_
\ba_
\bm_
\be_
\br_
\be_
\bf attribute using the -
\b-n
\bn option to
671 the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be or l
\blo
\boc
\bca
\bal
\bl builtin commands (see the descriptions of d
\bde
\bec
\bcl
\bla
\bar
\bre
\be
672 and l
\blo
\boc
\bca
\bal
\bl below) to create a _
\bn_
\ba_
\bm_
\be_
\br_
\be_
\bf, or a reference to another vari-
673 able. This allows variables to be manipulated indirectly. Whenever
674 the nameref variable is referenced or assigned to, the operation is
675 actually performed on the variable specified by the nameref variable's
676 value. A nameref is commonly used within shell functions to refer to a
677 variable whose name is passed as an argument to the function. For
678 instance, if a variable name is passed to a shell function as its first
681 inside the function creates a nameref variable r
\bre
\bef
\bf whose value is the
682 variable name passed as the first argument. References and assignments
683 to r
\bre
\bef
\bf are treated as references and assignments to the variable whose
684 name was passed as $
\b$1
\b1. If the control variable in a f
\bfo
\bor
\br loop has the
685 nameref attribute, the list of words can be a list of shell variables,
686 and a name reference will be established for each word in the list, in
687 turn, when the loop is executed. Array variables cannot be given the
688 -
\b-n
\bn attribute. However, nameref variables can reference array variables
689 and subscripted array variables. Namerefs can be unset using the -
\b-n
\bn
690 option to the u
\bun
\bns
\bse
\bet
\bt builtin. Otherwise, if u
\bun
\bns
\bse
\bet
\bt is executed with the
691 name of a nameref variable as an argument, the variable referenced by
692 the nameref variable will be unset.
694 P
\bPo
\bos
\bsi
\bit
\bti
\bio
\bon
\bna
\bal
\bl P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\brs
\bs
695 A _
\bp_
\bo_
\bs_
\bi_
\bt_
\bi_
\bo_
\bn_
\ba_
\bl _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is a parameter denoted by one or more digits,
696 other than the single digit 0. Positional parameters are assigned from
697 the shell's arguments when it is invoked, and may be reassigned using
698 the s
\bse
\bet
\bt builtin command. Positional parameters may not be assigned to
699 with assignment statements. The positional parameters are temporarily
700 replaced when a shell function is executed (see F
\bFU
\bUN
\bNC
\bCT
\bTI
\bIO
\bON
\bNS
\bS below).
702 When a positional parameter consisting of more than a single digit is
703 expanded, it must be enclosed in braces (see E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below).
705 S
\bSp
\bpe
\bec
\bci
\bia
\bal
\bl P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\brs
\bs
706 The shell treats several parameters specially. These parameters may
707 only be referenced; assignment to them is not allowed.
708 *
\b* Expands to the positional parameters, starting from one. When
709 the expansion is not within double quotes, each positional
710 parameter expands to a separate word. In contexts where it is
711 performed, those words are subject to further word splitting and
712 pathname expansion. When the expansion occurs within double
713 quotes, it expands to a single word with the value of each
714 parameter separated by the first character of the I
\bIF
\bFS
\bS special
715 variable. That is, "$
\b$*
\b*" is equivalent to "$
\b$1
\b1_
\bc$
\b$2
\b2_
\bc.
\b..
\b..
\b.", where _
\bc
716 is the first character of the value of the I
\bIF
\bFS
\bS variable. If I
\bIF
\bFS
\bS
717 is unset, the parameters are separated by spaces. If I
\bIF
\bFS
\bS is
718 null, the parameters are joined without intervening separators.
719 @
\b@ Expands to the positional parameters, starting from one. When
720 the expansion occurs within double quotes, each parameter
721 expands to a separate word. That is, "$
\b$@
\b@" is equivalent to "$
\b$1
\b1"
722 "$
\b$2
\b2" ... If the double-quoted expansion occurs within a word,
723 the expansion of the first parameter is joined with the begin-
724 ning part of the original word, and the expansion of the last
725 parameter is joined with the last part of the original word.
726 When there are no positional parameters, "$
\b$@
\b@" and $
\b$@
\b@ expand to
727 nothing (i.e., they are removed).
728 #
\b# Expands to the number of positional parameters in decimal.
729 ?
\b? Expands to the exit status of the most recently executed fore-
731 -
\b- Expands to the current option flags as specified upon invoca-
732 tion, by the s
\bse
\bet
\bt builtin command, or those set by the shell
733 itself (such as the -
\b-i
\bi option).
734 $
\b$ Expands to the process ID of the shell. In a () subshell, it
735 expands to the process ID of the current shell, not the sub-
737 !
\b! Expands to the process ID of the job most recently placed into
738 the background, whether executed as an asynchronous command or
739 using the b
\bbg
\bg builtin (see J
\bJO
\bOB
\bB C
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL below).
740 0
\b0 Expands to the name of the shell or shell script. This is set
741 at shell initialization. If b
\bba
\bas
\bsh
\bh is invoked with a file of com-
742 mands, $
\b$0
\b0 is set to the name of that file. If b
\bba
\bas
\bsh
\bh is started
743 with the -
\b-c
\bc option, then $
\b$0
\b0 is set to the first argument after
744 the string to be executed, if one is present. Otherwise, it is
745 set to the filename used to invoke b
\bba
\bas
\bsh
\bh, as given by argument
747 _
\b_ At shell startup, set to the absolute pathname used to invoke
748 the shell or shell script being executed as passed in the envi-
749 ronment or argument list. Subsequently, expands to the last
750 argument to the previous command, after expansion. Also set to
751 the full pathname used to invoke each command executed and
752 placed in the environment exported to that command. When check-
753 ing mail, this parameter holds the name of the mail file cur-
754 rently being checked.
756 S
\bSh
\bhe
\bel
\bll
\bl V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs
757 The following variables are set by the shell:
759 B
\bBA
\bAS
\bSH
\bH Expands to the full filename used to invoke this instance of
761 B
\bBA
\bAS
\bSH
\bHO
\bOP
\bPT
\bTS
\bS
762 A colon-separated list of enabled shell options. Each word in
763 the list is a valid argument for the -
\b-s
\bs option to the s
\bsh
\bho
\bop
\bpt
\bt
764 builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). The options
765 appearing in B
\bBA
\bAS
\bSH
\bHO
\bOP
\bPT
\bTS
\bS are those reported as _
\bo_
\bn by s
\bsh
\bho
\bop
\bpt
\bt. If
766 this variable is in the environment when b
\bba
\bas
\bsh
\bh starts up, each
767 shell option in the list will be enabled before reading any
768 startup files. This variable is read-only.
769 B
\bBA
\bAS
\bSH
\bHP
\bPI
\bID
\bD
770 Expands to the process ID of the current b
\bba
\bas
\bsh
\bh process. This
771 differs from $
\b$$
\b$ under certain circumstances, such as subshells
772 that do not require b
\bba
\bas
\bsh
\bh to be re-initialized.
773 B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAL
\bLI
\bIA
\bAS
\bSE
\bES
\bS
774 An associative array variable whose members correspond to the
775 internal list of aliases as maintained by the a
\bal
\bli
\bia
\bas
\bs builtin.
776 Elements added to this array appear in the alias list; unsetting
777 array elements cause aliases to be removed from the alias list.
778 B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGC
\bC
779 An array variable whose values are the number of parameters in
780 each frame of the current b
\bba
\bas
\bsh
\bh execution call stack. The number
781 of parameters to the current subroutine (shell function or
782 script executed with .
\b. or s
\bso
\bou
\bur
\brc
\bce
\be) is at the top of the stack.
783 When a subroutine is executed, the number of parameters passed
784 is pushed onto B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGC
\bC. The shell sets B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGC
\bC only when in
785 extended debugging mode (see the description of the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg
786 option to the s
\bsh
\bho
\bop
\bpt
\bt builtin below)
787 B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGV
\bV
788 An array variable containing all of the parameters in the cur-
789 rent b
\bba
\bas
\bsh
\bh execution call stack. The final parameter of the last
790 subroutine call is at the top of the stack; the first parameter
791 of the initial call is at the bottom. When a subroutine is exe-
792 cuted, the parameters supplied are pushed onto B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGV
\bV. The
793 shell sets B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGV
\bV only when in extended debugging mode (see
794 the description of the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg option to the s
\bsh
\bho
\bop
\bpt
\bt builtin
796 B
\bBA
\bAS
\bSH
\bH_
\b_C
\bCM
\bMD
\bDS
\bS
797 An associative array variable whose members correspond to the
798 internal hash table of commands as maintained by the h
\bha
\bas
\bsh
\bh
799 builtin. Elements added to this array appear in the hash table;
800 unsetting array elements cause commands to be removed from the
802 B
\bBA
\bAS
\bSH
\bH_
\b_C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD
803 The command currently being executed or about to be executed,
804 unless the shell is executing a command as the result of a trap,
805 in which case it is the command executing at the time of the
807 B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN_
\b_S
\bST
\bTR
\bRI
\bIN
\bNG
\bG
808 The command argument to the -
\b-c
\bc invocation option.
809 B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO
810 An array variable whose members are the line numbers in source
811 files where each corresponding member of F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE was invoked.
812 $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO[
\b[_
\b$_
\bi]
\b]}
\b} is the line number in the source file
813 ($
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE[
\b[_
\b$_
\bi_
\b+_
\b1]
\b]}
\b}) where $
\b${
\b{F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE[
\b[_
\b$_
\bi]
\b]}
\b} was called (or
814 $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO[
\b[_
\b$_
\bi_
\b-_
\b1]
\b]}
\b} if referenced within another shell func-
815 tion). Use L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO to obtain the current line number.
816 B
\bBA
\bAS
\bSH
\bH_
\b_R
\bRE
\bEM
\bMA
\bAT
\bTC
\bCH
\bH
817 An array variable whose members are assigned by the =
\b=~
\b~ binary
818 operator to the [
\b[[
\b[ conditional command. The element with index
819 0 is the portion of the string matching the entire regular
820 expression. The element with index _
\bn is the portion of the
821 string matching the _
\bnth parenthesized subexpression. This vari-
823 B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE
824 An array variable whose members are the source filenames where
825 the corresponding shell function names in the F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE array
826 variable are defined. The shell function $
\b${
\b{F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE[
\b[_
\b$_
\bi]
\b]}
\b} is
827 defined in the file $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE[
\b[_
\b$_
\bi]
\b]}
\b} and called from
828 $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE[
\b[_
\b$_
\bi_
\b+_
\b1]
\b]}
\b}.
829 B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSU
\bUB
\bBS
\bSH
\bHE
\bEL
\bLL
\bL
830 Incremented by one within each subshell or subshell environment
831 when the shell begins executing in that environment. The ini-
833 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO
834 A readonly array variable whose members hold version information
835 for this instance of b
\bba
\bas
\bsh
\bh. The values assigned to the array
836 members are as follows:
837 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[0]
\b] The major version number (the _
\br_
\be_
\bl_
\be_
\ba_
\bs_
\be).
838 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[1]
\b] The minor version number (the _
\bv_
\be_
\br_
\bs_
\bi_
\bo_
\bn).
839 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[2]
\b] The patch level.
840 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[3]
\b] The build version.
841 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[4]
\b] The release status (e.g., _
\bb_
\be_
\bt_
\ba_
\b1).
842 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIN
\bNF
\bFO
\bO[
\b[5]
\b] The value of M
\bMA
\bAC
\bCH
\bHT
\bTY
\bYP
\bPE
\bE.
843 B
\bBA
\bAS
\bSH
\bH_
\b_V
\bVE
\bER
\bRS
\bSI
\bIO
\bON
\bN
844 Expands to a string describing the version of this instance of
846 C
\bCO
\bOM
\bMP
\bP_
\b_C
\bCW
\bWO
\bOR
\bRD
\bD
847 An index into $
\b${
\b{C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDS
\bS}
\b} of the word containing the current
848 cursor position. This variable is available only in shell func-
849 tions invoked by the programmable completion facilities (see
850 P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn below).
851 C
\bCO
\bOM
\bMP
\bP_
\b_K
\bKE
\bEY
\bY
852 The key (or final key of a key sequence) used to invoke the cur-
853 rent completion function.
854 C
\bCO
\bOM
\bMP
\bP_
\b_L
\bLI
\bIN
\bNE
\bE
855 The current command line. This variable is available only in
856 shell functions and external commands invoked by the pro-
857 grammable completion facilities (see P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn
859 C
\bCO
\bOM
\bMP
\bP_
\b_P
\bPO
\bOI
\bIN
\bNT
\bT
860 The index of the current cursor position relative to the begin-
861 ning of the current command. If the current cursor position is
862 at the end of the current command, the value of this variable is
863 equal to $
\b${
\b{#
\b#C
\bCO
\bOM
\bMP
\bP_
\b_L
\bLI
\bIN
\bNE
\bE}
\b}. This variable is available only in
864 shell functions and external commands invoked by the pro-
865 grammable completion facilities (see P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn
867 C
\bCO
\bOM
\bMP
\bP_
\b_T
\bTY
\bYP
\bPE
\bE
868 Set to an integer value corresponding to the type of completion
869 attempted that caused a completion function to be called: _
\bT_
\bA_
\bB,
870 for normal completion, _
\b?, for listing completions after succes-
871 sive tabs, _
\b!, for listing alternatives on partial word comple-
872 tion, _
\b@, to list completions if the word is not unmodified, or
873 _
\b%, for menu completion. This variable is available only in
874 shell functions and external commands invoked by the pro-
875 grammable completion facilities (see P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn
877 C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDB
\bBR
\bRE
\bEA
\bAK
\bKS
\bS
878 The set of characters that the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be library treats as word
879 separators when performing word completion. If C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDB
\bBR
\bRE
\bEA
\bAK
\bKS
\bS
880 is unset, it loses its special properties, even if it is subse-
882 C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDS
\bS
883 An array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) consisting of the individ-
884 ual words in the current command line. The line is split into
885 words as r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be would split it, using C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDB
\bBR
\bRE
\bEA
\bAK
\bKS
\bS as
886 described above. This variable is available only in shell func-
887 tions invoked by the programmable completion facilities (see
888 P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn below).
889 C
\bCO
\bOP
\bPR
\bRO
\bOC
\bC An array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) created to hold the file
890 descriptors for output from and input to an unnamed coprocess
891 (see C
\bCo
\bop
\bpr
\bro
\boc
\bce
\bes
\bss
\bse
\bes
\bs above).
892 D
\bDI
\bIR
\bRS
\bST
\bTA
\bAC
\bCK
\bK
893 An array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) containing the current con-
894 tents of the directory stack. Directories appear in the stack
895 in the order they are displayed by the d
\bdi
\bir
\brs
\bs builtin. Assigning
896 to members of this array variable may be used to modify directo-
897 ries already in the stack, but the p
\bpu
\bus
\bsh
\bhd
\bd and p
\bpo
\bop
\bpd
\bd builtins must
898 be used to add and remove directories. Assignment to this vari-
899 able will not change the current directory. If D
\bDI
\bIR
\bRS
\bST
\bTA
\bAC
\bCK
\bK is
900 unset, it loses its special properties, even if it is subse-
902 E
\bEU
\bUI
\bID
\bD Expands to the effective user ID of the current user, initial-
903 ized at shell startup. This variable is readonly.
904 F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE
905 An array variable containing the names of all shell functions
906 currently in the execution call stack. The element with index 0
907 is the name of any currently-executing shell function. The bot-
908 tom-most element (the one with the highest index) is "main".
909 This variable exists only when a shell function is executing.
910 Assignments to F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE have no effect and return an error sta-
911 tus. If F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE is unset, it loses its special properties,
912 even if it is subsequently reset.
914 This variable can be used with B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO and B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE.
915 Each element of F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE has corresponding elements in
916 B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO and B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE to describe the call stack. For
917 instance, $
\b${
\b{F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE[
\b[_
\b$_
\bi]
\b]}
\b} was called from the file
918 $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_S
\bSO
\bOU
\bUR
\bRC
\bCE
\bE[
\b[_
\b$_
\bi_
\b+_
\b1]
\b]}
\b} at line number $
\b${
\b{B
\bBA
\bAS
\bSH
\bH_
\b_L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO[
\b[_
\b$_
\bi]
\b]}
\b}. The
919 c
\bca
\bal
\bll
\ble
\ber
\br builtin displays the current call stack using this infor-
921 G
\bGR
\bRO
\bOU
\bUP
\bPS
\bS An array variable containing the list of groups of which the
922 current user is a member. Assignments to G
\bGR
\bRO
\bOU
\bUP
\bPS
\bS have no effect
923 and return an error status. If G
\bGR
\bRO
\bOU
\bUP
\bPS
\bS is unset, it loses its
924 special properties, even if it is subsequently reset.
925 H
\bHI
\bIS
\bST
\bTC
\bCM
\bMD
\bD
926 The history number, or index in the history list, of the current
927 command. If H
\bHI
\bIS
\bST
\bTC
\bCM
\bMD
\bD is unset, it loses its special properties,
928 even if it is subsequently reset.
929 H
\bHO
\bOS
\bST
\bTN
\bNA
\bAM
\bME
\bE
930 Automatically set to the name of the current host.
931 H
\bHO
\bOS
\bST
\bTT
\bTY
\bYP
\bPE
\bE
932 Automatically set to a string that uniquely describes the type
933 of machine on which b
\bba
\bas
\bsh
\bh is executing. The default is system-
935 L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO Each time this parameter is referenced, the shell substitutes a
936 decimal number representing the current sequential line number
937 (starting with 1) within a script or function. When not in a
938 script or function, the value substituted is not guaranteed to
939 be meaningful. If L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO is unset, it loses its special proper-
940 ties, even if it is subsequently reset.
941 M
\bMA
\bAC
\bCH
\bHT
\bTY
\bYP
\bPE
\bE
942 Automatically set to a string that fully describes the system
943 type on which b
\bba
\bas
\bsh
\bh is executing, in the standard GNU _
\bc_
\bp_
\bu_
\b-_
\bc_
\bo_
\bm_
\b-
944 _
\bp_
\ba_
\bn_
\by_
\b-_
\bs_
\by_
\bs_
\bt_
\be_
\bm format. The default is system-dependent.
945 M
\bMA
\bAP
\bPF
\bFI
\bIL
\bLE
\bE
946 An array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) created to hold the text
947 read by the m
\bma
\bap
\bpf
\bfi
\bil
\ble
\be builtin when no variable name is supplied.
948 O
\bOL
\bLD
\bDP
\bPW
\bWD
\bD The previous working directory as set by the c
\bcd
\bd command.
949 O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG The value of the last option argument processed by the g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs
950 builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
951 O
\bOP
\bPT
\bTI
\bIN
\bND
\bD The index of the next argument to be processed by the g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs
952 builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
953 O
\bOS
\bST
\bTY
\bYP
\bPE
\bE Automatically set to a string that describes the operating sys-
954 tem on which b
\bba
\bas
\bsh
\bh is executing. The default is system-depen-
956 P
\bPI
\bIP
\bPE
\bES
\bST
\bTA
\bAT
\bTU
\bUS
\bS
957 An array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs below) containing a list of exit
958 status values from the processes in the most-recently-executed
959 foreground pipeline (which may contain only a single command).
960 P
\bPP
\bPI
\bID
\bD The process ID of the shell's parent. This variable is read-
962 P
\bPW
\bWD
\bD The current working directory as set by the c
\bcd
\bd command.
963 R
\bRA
\bAN
\bND
\bDO
\bOM
\bM Each time this parameter is referenced, a random integer between
964 0 and 32767 is generated. The sequence of random numbers may be
965 initialized by assigning a value to R
\bRA
\bAN
\bND
\bDO
\bOM
\bM. If R
\bRA
\bAN
\bND
\bDO
\bOM
\bM is unset,
966 it loses its special properties, even if it is subsequently
968 R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE_
\b_L
\bLI
\bIN
\bNE
\bE
969 The contents of the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be line buffer, for use with "bind -x"
970 (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
971 R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE_
\b_P
\bPO
\bOI
\bIN
\bNT
\bT
972 The position of the insertion point in the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be line buffer,
973 for use with "bind -x" (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
974 R
\bRE
\bEP
\bPL
\bLY
\bY Set to the line of input read by the r
\bre
\bea
\bad
\bd builtin command when
975 no arguments are supplied.
976 S
\bSE
\bEC
\bCO
\bON
\bND
\bDS
\bS
977 Each time this parameter is referenced, the number of seconds
978 since shell invocation is returned. If a value is assigned to
979 S
\bSE
\bEC
\bCO
\bON
\bND
\bDS
\bS, the value returned upon subsequent references is the
980 number of seconds since the assignment plus the value assigned.
981 If S
\bSE
\bEC
\bCO
\bON
\bND
\bDS
\bS is unset, it loses its special properties, even if it
982 is subsequently reset.
983 S
\bSH
\bHE
\bEL
\bLL
\bLO
\bOP
\bPT
\bTS
\bS
984 A colon-separated list of enabled shell options. Each word in
985 the list is a valid argument for the -
\b-o
\bo option to the s
\bse
\bet
\bt
986 builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). The options
987 appearing in S
\bSH
\bHE
\bEL
\bLL
\bLO
\bOP
\bPT
\bTS
\bS are those reported as _
\bo_
\bn by s
\bse
\bet
\bt -
\b-o
\bo. If
988 this variable is in the environment when b
\bba
\bas
\bsh
\bh starts up, each
989 shell option in the list will be enabled before reading any
990 startup files. This variable is read-only.
991 S
\bSH
\bHL
\bLV
\bVL
\bL Incremented by one each time an instance of b
\bba
\bas
\bsh
\bh is started.
992 U
\bUI
\bID
\bD Expands to the user ID of the current user, initialized at shell
993 startup. This variable is readonly.
995 The following variables are used by the shell. In some cases, b
\bba
\bas
\bsh
\bh
996 assigns a default value to a variable; these cases are noted below.
998 B
\bBA
\bAS
\bSH
\bH_
\b_C
\bCO
\bOM
\bMP
\bPA
\bAT
\bT
999 The value is used to set the shell's compatibility level. See
1000 the description of the s
\bsh
\bho
\bop
\bpt
\bt builtin below under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN
1001 C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS for a description of the various compatibility levels
1002 and their effects. The value may be a decimal number (e.g.,
1003 4.2) or an integer (e.g., 42) corresponding to the desired com-
1004 patibility level. If B
\bBA
\bAS
\bSH
\bH_
\b_C
\bCO
\bOM
\bMP
\bPA
\bAT
\bT is unset or set to the empty
1005 string, the compatibility level is set to the default for the
1006 current version. If B
\bBA
\bAS
\bSH
\bH_
\b_C
\bCO
\bOM
\bMP
\bPA
\bAT
\bT is set to a value that is not
1007 one of the valid compatibility levels, the shell prints an error
1008 message and sets the compatibility level to the default for the
1009 current version. The valid compatibility levels correspond to
1010 the compatibility options accepted by the s
\bsh
\bho
\bop
\bpt
\bt builtin
1011 described below (for example, c
\bco
\bom
\bmp
\bpa
\bat
\bt4
\b42
\b2 means that 4.2 and 42 are
1012 valid values). The current version is also a valid value.
1013 B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV
1014 If this parameter is set when b
\bba
\bas
\bsh
\bh is executing a shell script,
1015 its value is interpreted as a filename containing commands to
1016 initialize the shell, as in _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc. The value of B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV is
1017 subjected to parameter expansion, command substitution, and
1018 arithmetic expansion before being interpreted as a filename.
1019 P
\bPA
\bAT
\bTH
\bH is not used to search for the resultant filename.
1020 B
\bBA
\bAS
\bSH
\bH_
\b_X
\bXT
\bTR
\bRA
\bAC
\bCE
\bEF
\bFD
\bD
1021 If set to an integer corresponding to a valid file descriptor,
1022 b
\bba
\bas
\bsh
\bh will write the trace output generated when _
\bs_
\be_
\bt _
\b-_
\bx is
1023 enabled to that file descriptor. The file descriptor is closed
1024 when B
\bBA
\bAS
\bSH
\bH_
\b_X
\bXT
\bTR
\bRA
\bAC
\bCE
\bEF
\bFD
\bD is unset or assigned a new value. Unsetting
1025 B
\bBA
\bAS
\bSH
\bH_
\b_X
\bXT
\bTR
\bRA
\bAC
\bCE
\bEF
\bFD
\bD or assigning it the empty string causes the trace
1026 output to be sent to the standard error. Note that setting
1027 B
\bBA
\bAS
\bSH
\bH_
\b_X
\bXT
\bTR
\bRA
\bAC
\bCE
\bEF
\bFD
\bD to 2 (the standard error file descriptor) and then
1028 unsetting it will result in the standard error being closed.
1029 C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH The search path for the c
\bcd
\bd command. This is a colon-separated
1030 list of directories in which the shell looks for destination
1031 directories specified by the c
\bcd
\bd command. A sample value is
1033 C
\bCH
\bHI
\bIL
\bLD
\bD_
\b_M
\bMA
\bAX
\bX
1034 Set the number of exited child status values for the shell to
1035 remember. Bash will not allow this value to be decreased below
1036 a POSIX-mandated minimum, and there is a maximum value (cur-
1037 rently 8192) that this may not exceed. The minimum value is
1039 C
\bCO
\bOL
\bLU
\bUM
\bMN
\bNS
\bS
1040 Used by the s
\bse
\bel
\ble
\bec
\bct
\bt compound command to determine the terminal
1041 width when printing selection lists. Automatically set if the
1042 c
\bch
\bhe
\bec
\bck
\bkw
\bwi
\bin
\bns
\bsi
\biz
\bze
\be option is enabled or in an interactive shell upon
1043 receipt of a S
\bSI
\bIG
\bGW
\bWI
\bIN
\bNC
\bCH
\bH.
1044 C
\bCO
\bOM
\bMP
\bPR
\bRE
\bEP
\bPL
\bLY
\bY
1045 An array variable from which b
\bba
\bas
\bsh
\bh reads the possible completions
1046 generated by a shell function invoked by the programmable com-
1047 pletion facility (see P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn below). Each
1048 array element contains one possible completion.
1049 E
\bEM
\bMA
\bAC
\bCS
\bS If b
\bba
\bas
\bsh
\bh finds this variable in the environment when the shell
1050 starts with value "t", it assumes that the shell is running in
1051 an Emacs shell buffer and disables line editing.
1052 E
\bEN
\bNV
\bV Similar to B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV; used when the shell is invoked in POSIX
1054 F
\bFC
\bCE
\bED
\bDI
\bIT
\bT The default editor for the f
\bfc
\bc builtin command.
1055 F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE
1056 A colon-separated list of suffixes to ignore when performing
1057 filename completion (see R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE below). A filename whose suf-
1058 fix matches one of the entries in F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is excluded from the
1059 list of matched filenames. A sample value is ".o:~".
1060 F
\bFU
\bUN
\bNC
\bCN
\bNE
\bES
\bST
\bT
1061 If set to a numeric value greater than 0, defines a maximum
1062 function nesting level. Function invocations that exceed this
1063 nesting level will cause the current command to abort.
1064 G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE
1065 A colon-separated list of patterns defining the set of filenames
1066 to be ignored by pathname expansion. If a filename matched by a
1067 pathname expansion pattern also matches one of the patterns in
1068 G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE, it is removed from the list of matches.
1069 H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL
1070 A colon-separated list of values controlling how commands are
1071 saved on the history list. If the list of values includes
1072 _
\bi_
\bg_
\bn_
\bo_
\br_
\be_
\bs_
\bp_
\ba_
\bc_
\be, lines which begin with a s
\bsp
\bpa
\bac
\bce
\be character are not
1073 saved in the history list. A value of _
\bi_
\bg_
\bn_
\bo_
\br_
\be_
\bd_
\bu_
\bp_
\bs causes lines
1074 matching the previous history entry to not be saved. A value of
1075 _
\bi_
\bg_
\bn_
\bo_
\br_
\be_
\bb_
\bo_
\bt_
\bh is shorthand for _
\bi_
\bg_
\bn_
\bo_
\br_
\be_
\bs_
\bp_
\ba_
\bc_
\be and _
\bi_
\bg_
\bn_
\bo_
\br_
\be_
\bd_
\bu_
\bp_
\bs. A value
1076 of _
\be_
\br_
\ba_
\bs_
\be_
\bd_
\bu_
\bp_
\bs causes all previous lines matching the current line
1077 to be removed from the history list before that line is saved.
1078 Any value not in the above list is ignored. If H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL is
1079 unset, or does not include a valid value, all lines read by the
1080 shell parser are saved on the history list, subject to the value
1081 of H
\bHI
\bIS
\bST
\bTI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE. The second and subsequent lines of a multi-line
1082 compound command are not tested, and are added to the history
1083 regardless of the value of H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL.
1084 H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE
1085 The name of the file in which command history is saved (see H
\bHI
\bIS
\bS-
\b-
1086 T
\bTO
\bOR
\bRY
\bY below). The default value is _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bh_
\bi_
\bs_
\bt_
\bo_
\br_
\by. If unset,
1087 the command history is not saved when a shell exits.
1088 H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bES
\bSI
\bIZ
\bZE
\bE
1089 The maximum number of lines contained in the history file. When
1090 this variable is assigned a value, the history file is trun-
1091 cated, if necessary, to contain no more than that number of
1092 lines by removing the oldest entries. The history file is also
1093 truncated to this size after writing it when a shell exits. If
1094 the value is 0, the history file is truncated to zero size.
1095 Non-numeric values and numeric values less than zero inhibit
1096 truncation. The shell sets the default value to the value of
1097 H
\bHI
\bIS
\bST
\bTS
\bSI
\bIZ
\bZE
\bE after reading any startup files.
1098 H
\bHI
\bIS
\bST
\bTI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE
1099 A colon-separated list of patterns used to decide which command
1100 lines should be saved on the history list. Each pattern is
1101 anchored at the beginning of the line and must match the com-
1102 plete line (no implicit `*
\b*' is appended). Each pattern is
1103 tested against the line after the checks specified by H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bN-
\b-
1104 T
\bTR
\bRO
\bOL
\bL are applied. In addition to the normal shell pattern
1105 matching characters, `&
\b&' matches the previous history line. `&
\b&'
1106 may be escaped using a backslash; the backslash is removed
1107 before attempting a match. The second and subsequent lines of a
1108 multi-line compound command are not tested, and are added to the
1109 history regardless of the value of H
\bHI
\bIS
\bST
\bTI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE.
1110 H
\bHI
\bIS
\bST
\bTS
\bSI
\bIZ
\bZE
\bE
1111 The number of commands to remember in the command history (see
1112 H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY below). If the value is 0, commands are not saved in
1113 the history list. Numeric values less than zero result in every
1114 command being saved on the history list (there is no limit).
1115 The shell sets the default value to 500 after reading any
1117 H
\bHI
\bIS
\bST
\bTT
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT
1118 If this variable is set and not null, its value is used as a
1119 format string for _
\bs_
\bt_
\br_
\bf_
\bt_
\bi_
\bm_
\be(3) to print the time stamp associated
1120 with each history entry displayed by the h
\bhi
\bis
\bst
\bto
\bor
\bry
\by builtin. If
1121 this variable is set, time stamps are written to the history
1122 file so they may be preserved across shell sessions. This uses
1123 the history comment character to distinguish timestamps from
1124 other history lines.
1125 H
\bHO
\bOM
\bME
\bE The home directory of the current user; the default argument for
1126 the c
\bcd
\bd builtin command. The value of this variable is also used
1127 when performing tilde expansion.
1128 H
\bHO
\bOS
\bST
\bTF
\bFI
\bIL
\bLE
\bE
1129 Contains the name of a file in the same format as _
\b/_
\be_
\bt_
\bc_
\b/_
\bh_
\bo_
\bs_
\bt_
\bs
1130 that should be read when the shell needs to complete a hostname.
1131 The list of possible hostname completions may be changed while
1132 the shell is running; the next time hostname completion is
1133 attempted after the value is changed, b
\bba
\bas
\bsh
\bh adds the contents of
1134 the new file to the existing list. If H
\bHO
\bOS
\bST
\bTF
\bFI
\bIL
\bLE
\bE is set, but has
1135 no value, or does not name a readable file, b
\bba
\bas
\bsh
\bh attempts to
1136 read _
\b/_
\be_
\bt_
\bc_
\b/_
\bh_
\bo_
\bs_
\bt_
\bs to obtain the list of possible hostname comple-
1137 tions. When H
\bHO
\bOS
\bST
\bTF
\bFI
\bIL
\bLE
\bE is unset, the hostname list is cleared.
1138 I
\bIF
\bFS
\bS The _
\bI_
\bn_
\bt_
\be_
\br_
\bn_
\ba_
\bl _
\bF_
\bi_
\be_
\bl_
\bd _
\bS_
\be_
\bp_
\ba_
\br_
\ba_
\bt_
\bo_
\br that is used for word splitting
1139 after expansion and to split lines into words with the r
\bre
\bea
\bad
\bd
1140 builtin command. The default value is ``<space><tab><new-
1142 I
\bIG
\bGN
\bNO
\bOR
\bRE
\bEE
\bEO
\bOF
\bF
1143 Controls the action of an interactive shell on receipt of an E
\bEO
\bOF
\bF
1144 character as the sole input. If set, the value is the number of
1145 consecutive E
\bEO
\bOF
\bF characters which must be typed as the first
1146 characters on an input line before b
\bba
\bas
\bsh
\bh exits. If the variable
1147 exists but does not have a numeric value, or has no value, the
1148 default value is 10. If it does not exist, E
\bEO
\bOF
\bF signifies the
1149 end of input to the shell.
1150 I
\bIN
\bNP
\bPU
\bUT
\bTR
\bRC
\bC
1151 The filename for the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be startup file, overriding the
1152 default of _
\b~_
\b/_
\b._
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc (see R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE below).
1153 L
\bLA
\bAN
\bNG
\bG Used to determine the locale category for any category not
1154 specifically selected with a variable starting with L
\bLC
\bC_
\b_.
1155 L
\bLC
\bC_
\b_A
\bAL
\bLL
\bL This variable overrides the value of L
\bLA
\bAN
\bNG
\bG and any other L
\bLC
\bC_
\b_
1156 variable specifying a locale category.
1157 L
\bLC
\bC_
\b_C
\bCO
\bOL
\bLL
\bLA
\bAT
\bTE
\bE
1158 This variable determines the collation order used when sorting
1159 the results of pathname expansion, and determines the behavior
1160 of range expressions, equivalence classes, and collating
1161 sequences within pathname expansion and pattern matching.
1162 L
\bLC
\bC_
\b_C
\bCT
\bTY
\bYP
\bPE
\bE
1163 This variable determines the interpretation of characters and
1164 the behavior of character classes within pathname expansion and
1166 L
\bLC
\bC_
\b_M
\bME
\bES
\bSS
\bSA
\bAG
\bGE
\bES
\bS
1167 This variable determines the locale used to translate double-
1168 quoted strings preceded by a $
\b$.
1169 L
\bLC
\bC_
\b_N
\bNU
\bUM
\bME
\bER
\bRI
\bIC
\bC
1170 This variable determines the locale category used for number
1172 L
\bLI
\bIN
\bNE
\bES
\bS Used by the s
\bse
\bel
\ble
\bec
\bct
\bt compound command to determine the column
1173 length for printing selection lists. Automatically set if the
1174 c
\bch
\bhe
\bec
\bck
\bkw
\bwi
\bin
\bns
\bsi
\biz
\bze
\be option is enabled or in an interactive shell upon
1175 receipt of a S
\bSI
\bIG
\bGW
\bWI
\bIN
\bNC
\bCH
\bH.
1176 M
\bMA
\bAI
\bIL
\bL If this parameter is set to a file or directory name and the
1177 M
\bMA
\bAI
\bIL
\bLP
\bPA
\bAT
\bTH
\bH variable is not set, b
\bba
\bas
\bsh
\bh informs the user of the
1178 arrival of mail in the specified file or Maildir-format direc-
1180 M
\bMA
\bAI
\bIL
\bLC
\bCH
\bHE
\bEC
\bCK
\bK
1181 Specifies how often (in seconds) b
\bba
\bas
\bsh
\bh checks for mail. The
1182 default is 60 seconds. When it is time to check for mail, the
1183 shell does so before displaying the primary prompt. If this
1184 variable is unset, or set to a value that is not a number
1185 greater than or equal to zero, the shell disables mail checking.
1186 M
\bMA
\bAI
\bIL
\bLP
\bPA
\bAT
\bTH
\bH
1187 A colon-separated list of filenames to be checked for mail. The
1188 message to be printed when mail arrives in a particular file may
1189 be specified by separating the filename from the message with a
1190 `?'. When used in the text of the message, $
\b$_
\b_ expands to the
1191 name of the current mailfile. Example:
1192 M
\bMA
\bAI
\bIL
\bLP
\bPA
\bAT
\bTH
\bH='/var/mail/bfox?"You have mail":~/shell-mail?"$_ has
1194 B
\bBa
\bas
\bsh
\bh supplies a default value for this variable, but the loca-
1195 tion of the user mail files that it uses is system dependent
1196 (e.g., /var/mail/$
\b$U
\bUS
\bSE
\bER
\bR).
1197 O
\bOP
\bPT
\bTE
\bER
\bRR
\bR If set to the value 1, b
\bba
\bas
\bsh
\bh displays error messages generated by
1198 the g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs builtin command (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
1199 O
\bOP
\bPT
\bTE
\bER
\bRR
\bR is initialized to 1 each time the shell is invoked or a
1200 shell script is executed.
1201 P
\bPA
\bAT
\bTH
\bH The search path for commands. It is a colon-separated list of
1202 directories in which the shell looks for commands (see C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD
1203 E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN below). A zero-length (null) directory name in the
1204 value of P
\bPA
\bAT
\bTH
\bH indicates the current directory. A null directory
1205 name may appear as two adjacent colons, or as an initial or
1206 trailing colon. The default path is system-dependent, and is
1207 set by the administrator who installs b
\bba
\bas
\bsh
\bh. A common value is
1208 ``/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin''.
1209 P
\bPO
\bOS
\bSI
\bIX
\bXL
\bLY
\bY_
\b_C
\bCO
\bOR
\bRR
\bRE
\bEC
\bCT
\bT
1210 If this variable is in the environment when b
\bba
\bas
\bsh
\bh starts, the
1211 shell enters _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be before reading the startup files, as if
1212 the -
\b--
\b-p
\bpo
\bos
\bsi
\bix
\bx invocation option had been supplied. If it is set
1213 while the shell is running, b
\bba
\bas
\bsh
\bh enables _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be, as if the
1214 command _
\bs_
\be_
\bt _
\b-_
\bo _
\bp_
\bo_
\bs_
\bi_
\bx had been executed.
1215 P
\bPR
\bRO
\bOM
\bMP
\bPT
\bT_
\b_C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD
1216 If set, the value is executed as a command prior to issuing each
1218 P
\bPR
\bRO
\bOM
\bMP
\bPT
\bT_
\b_D
\bDI
\bIR
\bRT
\bTR
\bRI
\bIM
\bM
1219 If set to a number greater than zero, the value is used as the
1220 number of trailing directory components to retain when expanding
1221 the \
\b\w
\bw and \
\b\W
\bW prompt string escapes (see P
\bPR
\bRO
\bOM
\bMP
\bPT
\bTI
\bIN
\bNG
\bG below).
1222 Characters removed are replaced with an ellipsis.
1223 P
\bPS
\bS1
\b1 The value of this parameter is expanded (see P
\bPR
\bRO
\bOM
\bMP
\bPT
\bTI
\bIN
\bNG
\bG below)
1224 and used as the primary prompt string. The default value is
1225 ``\
\b\s
\bs-
\b-\
\b\v
\bv\
\b\$
\b$ ''.
1226 P
\bPS
\bS2
\b2 The value of this parameter is expanded as with P
\bPS
\bS1
\b1 and used as
1227 the secondary prompt string. The default is ``>
\b> ''.
1228 P
\bPS
\bS3
\b3 The value of this parameter is used as the prompt for the s
\bse
\bel
\ble
\bec
\bct
\bt
1229 command (see S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR above).
1230 P
\bPS
\bS4
\b4 The value of this parameter is expanded as with P
\bPS
\bS1
\b1 and the
1231 value is printed before each command b
\bba
\bas
\bsh
\bh displays during an
1232 execution trace. The first character of P
\bPS
\bS4
\b4 is replicated mul-
1233 tiple times, as necessary, to indicate multiple levels of indi-
1234 rection. The default is ``+
\b+ ''.
1235 S
\bSH
\bHE
\bEL
\bLL
\bL The full pathname to the shell is kept in this environment vari-
1236 able. If it is not set when the shell starts, b
\bba
\bas
\bsh
\bh assigns to
1237 it the full pathname of the current user's login shell.
1238 T
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT
1239 The value of this parameter is used as a format string specify-
1240 ing how the timing information for pipelines prefixed with the
1241 t
\bti
\bim
\bme
\be reserved word should be displayed. The %
\b% character intro-
1242 duces an escape sequence that is expanded to a time value or
1243 other information. The escape sequences and their meanings are
1244 as follows; the braces denote optional portions.
1245 %
\b%%
\b% A literal %
\b%.
1246 %
\b%[
\b[_
\bp]
\b][
\b[l
\bl]
\b]R
\bR The elapsed time in seconds.
1247 %
\b%[
\b[_
\bp]
\b][
\b[l
\bl]
\b]U
\bU The number of CPU seconds spent in user mode.
1248 %
\b%[
\b[_
\bp]
\b][
\b[l
\bl]
\b]S
\bS The number of CPU seconds spent in system mode.
1249 %
\b%P
\bP The CPU percentage, computed as (%U + %S) / %R.
1251 The optional _
\bp is a digit specifying the _
\bp_
\br_
\be_
\bc_
\bi_
\bs_
\bi_
\bo_
\bn, the number
1252 of fractional digits after a decimal point. A value of 0 causes
1253 no decimal point or fraction to be output. At most three places
1254 after the decimal point may be specified; values of _
\bp greater
1255 than 3 are changed to 3. If _
\bp is not specified, the value 3 is
1258 The optional l
\bl specifies a longer format, including minutes, of
1259 the form _
\bM_
\bMm_
\bS_
\bS._
\bF_
\bFs. The value of _
\bp determines whether or not
1260 the fraction is included.
1262 If this variable is not set, b
\bba
\bas
\bsh
\bh acts as if it had the value
1263 $
\b$'
\b'\
\b\n
\bnr
\bre
\bea
\bal
\bl\
\b\t
\bt%
\b%3
\b3l
\blR
\bR\
\b\n
\bnu
\bus
\bse
\ber
\br\
\b\t
\bt%
\b%3
\b3l
\blU
\bU\
\b\n
\bns
\bsy
\bys
\bs\
\b\t
\bt%
\b%3
\b3l
\blS
\bS'
\b'. If the value is null,
1264 no timing information is displayed. A trailing newline is added
1265 when the format string is displayed.
1266 T
\bTM
\bMO
\bOU
\bUT
\bT If set to a value greater than zero, T
\bTM
\bMO
\bOU
\bUT
\bT is treated as the
1267 default timeout for the r
\bre
\bea
\bad
\bd builtin. The s
\bse
\bel
\ble
\bec
\bct
\bt command termi-
1268 nates if input does not arrive after T
\bTM
\bMO
\bOU
\bUT
\bT seconds when input is
1269 coming from a terminal. In an interactive shell, the value is
1270 interpreted as the number of seconds to wait for a line of input
1271 after issuing the primary prompt. B
\bBa
\bas
\bsh
\bh terminates after waiting
1272 for that number of seconds if a complete line of input does not
1274 T
\bTM
\bMP
\bPD
\bDI
\bIR
\bR If set, b
\bba
\bas
\bsh
\bh uses its value as the name of a directory in which
1275 b
\bba
\bas
\bsh
\bh creates temporary files for the shell's use.
1276 a
\bau
\but
\bto
\bo_
\b_r
\bre
\bes
\bsu
\bum
\bme
\be
1277 This variable controls how the shell interacts with the user and
1278 job control. If this variable is set, single word simple com-
1279 mands without redirections are treated as candidates for resump-
1280 tion of an existing stopped job. There is no ambiguity allowed;
1281 if there is more than one job beginning with the string typed,
1282 the job most recently accessed is selected. The _
\bn_
\ba_
\bm_
\be of a
1283 stopped job, in this context, is the command line used to start
1284 it. If set to the value _
\be_
\bx_
\ba_
\bc_
\bt, the string supplied must match
1285 the name of a stopped job exactly; if set to _
\bs_
\bu_
\bb_
\bs_
\bt_
\br_
\bi_
\bn_
\bg, the
1286 string supplied needs to match a substring of the name of a
1287 stopped job. The _
\bs_
\bu_
\bb_
\bs_
\bt_
\br_
\bi_
\bn_
\bg value provides functionality analo-
1288 gous to the %
\b%?
\b? job identifier (see J
\bJO
\bOB
\bB C
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL below). If set
1289 to any other value, the supplied string must be a prefix of a
1290 stopped job's name; this provides functionality analogous to the
1291 %
\b%_
\bs_
\bt_
\br_
\bi_
\bn_
\bg job identifier.
1292 h
\bhi
\bis
\bst
\btc
\bch
\bha
\bar
\brs
\bs
1293 The two or three characters which control history expansion and
1294 tokenization (see H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below). The first character
1295 is the _
\bh_
\bi_
\bs_
\bt_
\bo_
\br_
\by _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn character, the character which signals
1296 the start of a history expansion, normally `!
\b!'. The second
1297 character is the _
\bq_
\bu_
\bi_
\bc_
\bk _
\bs_
\bu_
\bb_
\bs_
\bt_
\bi_
\bt_
\bu_
\bt_
\bi_
\bo_
\bn character, which is used as
1298 shorthand for re-running the previous command entered, substi-
1299 tuting one string for another in the command. The default is
1300 `^
\b^'. The optional third character is the character which indi-
1301 cates that the remainder of the line is a comment when found as
1302 the first character of a word, normally `#
\b#'. The history com-
1303 ment character causes history substitution to be skipped for the
1304 remaining words on the line. It does not necessarily cause the
1305 shell parser to treat the rest of the line as a comment.
1307 A
\bAr
\brr
\bra
\bay
\bys
\bs
1308 B
\bBa
\bas
\bsh
\bh provides one-dimensional indexed and associative array variables.
1309 Any variable may be used as an indexed array; the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin will
1310 explicitly declare an array. There is no maximum limit on the size of
1311 an array, nor any requirement that members be indexed or assigned con-
1312 tiguously. Indexed arrays are referenced using integers (including
1313 arithmetic expressions) and are zero-based; associative arrays are
1314 referenced using arbitrary strings. Unless otherwise noted, indexed
1315 array indices must be non-negative integers.
1317 An indexed array is created automatically if any variable is assigned
1318 to using the syntax _
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]=_
\bv_
\ba_
\bl_
\bu_
\be. The _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt is treated as
1319 an arithmetic expression that must evaluate to a number. To explicitly
1320 declare an indexed array, use d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-a
\ba _
\bn_
\ba_
\bm_
\be (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bM-
\b-
1321 M
\bMA
\bAN
\bND
\bDS
\bS below). d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-a
\ba _
\bn_
\ba_
\bm_
\be[
\b[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]
\b] is also accepted; the _
\bs_
\bu_
\bb_
\b-
1322 _
\bs_
\bc_
\br_
\bi_
\bp_
\bt is ignored.
1324 Associative arrays are created using d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-A
\bA _
\bn_
\ba_
\bm_
\be.
1326 Attributes may be specified for an array variable using the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be and
1327 r
\bre
\bea
\bad
\bdo
\bon
\bnl
\bly
\by builtins. Each attribute applies to all members of an array.
1329 Arrays are assigned to using compound assignments of the form
1330 _
\bn_
\ba_
\bm_
\be=(
\b(value_
\b1 ... value_
\bn)
\b), where each _
\bv_
\ba_
\bl_
\bu_
\be is of the form [_
\bs_
\bu_
\bb_
\b-
1331 _
\bs_
\bc_
\br_
\bi_
\bp_
\bt]=_
\bs_
\bt_
\br_
\bi_
\bn_
\bg. Indexed array assignments do not require anything but
1332 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg. When assigning to indexed arrays, if the optional brackets and
1333 subscript are supplied, that index is assigned to; otherwise the index
1334 of the element assigned is the last index assigned to by the statement
1335 plus one. Indexing starts at zero.
1337 When assigning to an associative array, the subscript is required.
1339 This syntax is also accepted by the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin. Individual array
1340 elements may be assigned to using the _
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]=_
\bv_
\ba_
\bl_
\bu_
\be syntax
1341 introduced above. When assigning to an indexed array, if _
\bn_
\ba_
\bm_
\be is sub-
1342 scripted by a negative number, that number is interpreted as relative
1343 to one greater than the maximum index of _
\bn_
\ba_
\bm_
\be, so negative indices
1344 count back from the end of the array, and an index of -1 references the
1347 Any element of an array may be referenced using ${_
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]}.
1348 The braces are required to avoid conflicts with pathname expansion. If
1349 _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt is @
\b@ or *
\b*, the word expands to all members of _
\bn_
\ba_
\bm_
\be. These
1350 subscripts differ only when the word appears within double quotes. If
1351 the word is double-quoted, ${_
\bn_
\ba_
\bm_
\be[*]} expands to a single word with the
1352 value of each array member separated by the first character of the I
\bIF
\bFS
\bS
1353 special variable, and ${_
\bn_
\ba_
\bm_
\be[@]} expands each element of _
\bn_
\ba_
\bm_
\be to a sep-
1354 arate word. When there are no array members, ${_
\bn_
\ba_
\bm_
\be[@]} expands to
1355 nothing. If the double-quoted expansion occurs within a word, the
1356 expansion of the first parameter is joined with the beginning part of
1357 the original word, and the expansion of the last parameter is joined
1358 with the last part of the original word. This is analogous to the
1359 expansion of the special parameters *
\b* and @
\b@ (see S
\bSp
\bpe
\bec
\bci
\bia
\bal
\bl P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\brs
\bs
1360 above). ${#_
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]} expands to the length of ${_
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\b-
1361 _
\bs_
\bc_
\br_
\bi_
\bp_
\bt]}. If _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt is *
\b* or @
\b@, the expansion is the number of ele-
1362 ments in the array. Referencing an array variable without a subscript
1363 is equivalent to referencing the array with a subscript of 0. If the
1364 _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt used to reference an element of an indexed array evaluates to
1365 a number less than zero, it is interpreted as relative to one greater
1366 than the maximum index of the array, so negative indices count back
1367 from the end of the array, and an index of -1 references the last ele-
1370 An array variable is considered set if a subscript has been assigned a
1371 value. The null string is a valid value.
1373 It is possible to obtain the keys (indices) of an array as well as the
1374 values. ${!
\b!_
\bn_
\ba_
\bm_
\be[_
\b@]} and ${!
\b!_
\bn_
\ba_
\bm_
\be[_
\b*]} expand to the indices assigned in
1375 array variable _
\bn_
\ba_
\bm_
\be. The treatment when in double quotes is similar to
1376 the expansion of the special parameters _
\b@ and _
\b* within double quotes.
1378 The u
\bun
\bns
\bse
\bet
\bt builtin is used to destroy arrays. u
\bun
\bns
\bse
\bet
\bt _
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt]
1379 destroys the array element at index _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt. Negative subscripts to
1380 indexed arrays are interpreted as described above. Care must be taken
1381 to avoid unwanted side effects caused by pathname expansion. u
\bun
\bns
\bse
\bet
\bt
1382 _
\bn_
\ba_
\bm_
\be, where _
\bn_
\ba_
\bm_
\be is an array, or u
\bun
\bns
\bse
\bet
\bt _
\bn_
\ba_
\bm_
\be[_
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt], where _
\bs_
\bu_
\bb_
\bs_
\bc_
\br_
\bi_
\bp_
\bt
1383 is *
\b* or @
\b@, removes the entire array.
1385 The d
\bde
\bec
\bcl
\bla
\bar
\bre
\be, l
\blo
\boc
\bca
\bal
\bl, and r
\bre
\bea
\bad
\bdo
\bon
\bnl
\bly
\by builtins each accept a -
\b-a
\ba option to
1386 specify an indexed array and a -
\b-A
\bA option to specify an associative
1387 array. If both options are supplied, -
\b-A
\bA takes precedence. The r
\bre
\bea
\bad
\bd
1388 builtin accepts a -
\b-a
\ba option to assign a list of words read from the
1389 standard input to an array. The s
\bse
\bet
\bt and d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtins display array
1390 values in a way that allows them to be reused as assignments.
1392 E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN
1393 Expansion is performed on the command line after it has been split into
1394 words. There are seven kinds of expansion performed: _
\bb_
\br_
\ba_
\bc_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn,
1395 _
\bt_
\bi_
\bl_
\bd_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn, _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br _
\ba_
\bn_
\bd _
\bv_
\ba_
\br_
\bi_
\ba_
\bb_
\bl_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn, _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd _
\bs_
\bu_
\bb_
\bs_
\bt_
\bi_
\bt_
\bu_
\b-
1396 _
\bt_
\bi_
\bo_
\bn, _
\ba_
\br_
\bi_
\bt_
\bh_
\bm_
\be_
\bt_
\bi_
\bc _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn, _
\bw_
\bo_
\br_
\bd _
\bs_
\bp_
\bl_
\bi_
\bt_
\bt_
\bi_
\bn_
\bg, and _
\bp_
\ba_
\bt_
\bh_
\bn_
\ba_
\bm_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn.
1398 The order of expansions is: brace expansion; tilde expansion, parameter
1399 and variable expansion, arithmetic expansion, and command substitution
1400 (done in a left-to-right fashion); word splitting; and pathname expan-
1403 On systems that can support it, there is an additional expansion avail-
1404 able: _
\bp_
\br_
\bo_
\bc_
\be_
\bs_
\bs _
\bs_
\bu_
\bb_
\bs_
\bt_
\bi_
\bt_
\bu_
\bt_
\bi_
\bo_
\bn. This is performed at the same time as
1405 tilde, parameter, variable, and arithmetic expansion and command sub-
1408 Only brace expansion, word splitting, and pathname expansion can change
1409 the number of words of the expansion; other expansions expand a single
1410 word to a single word. The only exceptions to this are the expansions
1411 of "$
\b$@
\b@" and "$
\b${
\b{_
\bn_
\ba_
\bm_
\be[
\b[@
\b@]
\b]}
\b}" as explained above (see P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS).
1413 B
\bBr
\bra
\bac
\bce
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
1414 _
\bB_
\br_
\ba_
\bc_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn is a mechanism by which arbitrary strings may be gener-
1415 ated. This mechanism is similar to _
\bp_
\ba_
\bt_
\bh_
\bn_
\ba_
\bm_
\be _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn, but the file-
1416 names generated need not exist. Patterns to be brace expanded take the
1417 form of an optional _
\bp_
\br_
\be_
\ba_
\bm_
\bb_
\bl_
\be, followed by either a series of comma-sep-
1418 arated strings or a sequence expression between a pair of braces, fol-
1419 lowed by an optional _
\bp_
\bo_
\bs_
\bt_
\bs_
\bc_
\br_
\bi_
\bp_
\bt. The preamble is prefixed to each
1420 string contained within the braces, and the postscript is then appended
1421 to each resulting string, expanding left to right.
1423 Brace expansions may be nested. The results of each expanded string
1424 are not sorted; left to right order is preserved. For example,
1425 a{
\b{d,c,b}
\b}e expands into `ade ace abe'.
1427 A sequence expression takes the form {
\b{_
\bx.
\b..
\b._
\by[
\b[.
\b..
\b._
\bi_
\bn_
\bc_
\br]
\b]}
\b}, where _
\bx and _
\by are
1428 either integers or single characters, and _
\bi_
\bn_
\bc_
\br, an optional increment,
1429 is an integer. When integers are supplied, the expression expands to
1430 each number between _
\bx and _
\by, inclusive. Supplied integers may be pre-
1431 fixed with _
\b0 to force each term to have the same width. When either _
\bx
1432 or _
\by begins with a zero, the shell attempts to force all generated
1433 terms to contain the same number of digits, zero-padding where neces-
1434 sary. When characters are supplied, the expression expands to each
1435 character lexicographically between _
\bx and _
\by, inclusive, using the
1436 default C locale. Note that both _
\bx and _
\by must be of the same type.
1437 When the increment is supplied, it is used as the difference between
1438 each term. The default increment is 1 or -1 as appropriate.
1440 Brace expansion is performed before any other expansions, and any char-
1441 acters special to other expansions are preserved in the result. It is
1442 strictly textual. B
\bBa
\bas
\bsh
\bh does not apply any syntactic interpretation to
1443 the context of the expansion or the text between the braces.
1445 A correctly-formed brace expansion must contain unquoted opening and
1446 closing braces, and at least one unquoted comma or a valid sequence
1447 expression. Any incorrectly formed brace expansion is left unchanged.
1448 A {
\b{ or ,
\b, may be quoted with a backslash to prevent its being considered
1449 part of a brace expression. To avoid conflicts with parameter expan-
1450 sion, the string $
\b${
\b{ is not considered eligible for brace expansion.
1452 This construct is typically used as shorthand when the common prefix of
1453 the strings to be generated is longer than in the above example:
1455 mkdir /usr/local/src/bash/{old,new,dist,bugs}
1457 chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
1459 Brace expansion introduces a slight incompatibility with historical
1460 versions of s
\bsh
\bh. s
\bsh
\bh does not treat opening or closing braces specially
1461 when they appear as part of a word, and preserves them in the output.
1462 B
\bBa
\bas
\bsh
\bh removes braces from words as a consequence of brace expansion.
1463 For example, a word entered to s
\bsh
\bh as _
\bf_
\bi_
\bl_
\be_
\b{_
\b1_
\b,_
\b2_
\b} appears identically in
1464 the output. The same word is output as _
\bf_
\bi_
\bl_
\be_
\b1 _
\bf_
\bi_
\bl_
\be_
\b2 after expansion by
1465 b
\bba
\bas
\bsh
\bh. If strict compatibility with s
\bsh
\bh is desired, start b
\bba
\bas
\bsh
\bh with the
1466 +
\b+B
\bB option or disable brace expansion with the +
\b+B
\bB option to the s
\bse
\bet
\bt com-
1467 mand (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
1469 T
\bTi
\bil
\bld
\bde
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
1470 If a word begins with an unquoted tilde character (`~
\b~'), all of the
1471 characters preceding the first unquoted slash (or all characters, if
1472 there is no unquoted slash) are considered a _
\bt_
\bi_
\bl_
\bd_
\be_
\b-_
\bp_
\br_
\be_
\bf_
\bi_
\bx. If none of
1473 the characters in the tilde-prefix are quoted, the characters in the
1474 tilde-prefix following the tilde are treated as a possible _
\bl_
\bo_
\bg_
\bi_
\bn _
\bn_
\ba_
\bm_
\be.
1475 If this login name is the null string, the tilde is replaced with the
1476 value of the shell parameter H
\bHO
\bOM
\bME
\bE. If H
\bHO
\bOM
\bME
\bE is unset, the home direc-
1477 tory of the user executing the shell is substituted instead. Other-
1478 wise, the tilde-prefix is replaced with the home directory associated
1479 with the specified login name.
1481 If the tilde-prefix is a `~+', the value of the shell variable P
\bPW
\bWD
\bD
1482 replaces the tilde-prefix. If the tilde-prefix is a `~-', the value of
1483 the shell variable O
\bOL
\bLD
\bDP
\bPW
\bWD
\bD, if it is set, is substituted. If the char-
1484 acters following the tilde in the tilde-prefix consist of a number _
\bN,
1485 optionally prefixed by a `+' or a `-', the tilde-prefix is replaced
1486 with the corresponding element from the directory stack, as it would be
1487 displayed by the d
\bdi
\bir
\brs
\bs builtin invoked with the tilde-prefix as an argu-
1488 ment. If the characters following the tilde in the tilde-prefix con-
1489 sist of a number without a leading `+' or `-', `+' is assumed.
1491 If the login name is invalid, or the tilde expansion fails, the word is
1494 Each variable assignment is checked for unquoted tilde-prefixes immedi-
1495 ately following a :
\b: or the first =
\b=. In these cases, tilde expansion is
1496 also performed. Consequently, one may use filenames with tildes in
1497 assignments to P
\bPA
\bAT
\bTH
\bH, M
\bMA
\bAI
\bIL
\bLP
\bPA
\bAT
\bTH
\bH, and C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH, and the shell assigns the
1500 P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\br E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
1501 The `$
\b$' character introduces parameter expansion, command substitution,
1502 or arithmetic expansion. The parameter name or symbol to be expanded
1503 may be enclosed in braces, which are optional but serve to protect the
1504 variable to be expanded from characters immediately following it which
1505 could be interpreted as part of the name.
1507 When braces are used, the matching ending brace is the first `}
\b}' not
1508 escaped by a backslash or within a quoted string, and not within an
1509 embedded arithmetic expansion, command substitution, or parameter
1512 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br}
1513 The value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is substituted. The braces are required
1514 when _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is a positional parameter with more than one
1515 digit, or when _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is followed by a character which is not
1516 to be interpreted as part of its name. The _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is a shell
1517 parameter as described above P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS) or an array reference
1518 (A
\bAr
\brr
\bra
\bay
\bys
\bs).
1520 If the first character of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is an exclamation point (!
\b!), it
1521 introduces a level of variable indirection. B
\bBa
\bas
\bsh
\bh uses the value of the
1522 variable formed from the rest of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br as the name of the variable;
1523 this variable is then expanded and that value is used in the rest of
1524 the substitution, rather than the value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br itself. This is
1525 known as _
\bi_
\bn_
\bd_
\bi_
\br_
\be_
\bc_
\bt _
\be_
\bx_
\bp_
\ba_
\bn_
\bs_
\bi_
\bo_
\bn. The exceptions to this are the expansions
1526 of ${!
\b!_
\bp_
\br_
\be_
\bf_
\bi_
\bx*
\b*} and ${!
\b!_
\bn_
\ba_
\bm_
\be[_
\b@]} described below. The exclamation point
1527 must immediately follow the left brace in order to introduce indirec-
1530 In each of the cases below, _
\bw_
\bo_
\br_
\bd is subject to tilde expansion, parame-
1531 ter expansion, command substitution, and arithmetic expansion.
1533 When not performing substring expansion, using the forms documented
1534 below (e.g., :
\b:-
\b-), b
\bba
\bas
\bsh
\bh tests for a parameter that is unset or null.
1535 Omitting the colon results in a test only for a parameter that is
1538 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:-
\b-_
\bw_
\bo_
\br_
\bd}
1539 U
\bUs
\bse
\be D
\bDe
\bef
\bfa
\bau
\bul
\blt
\bt V
\bVa
\bal
\blu
\bue
\bes
\bs. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is unset or null, the expan-
1540 sion of _
\bw_
\bo_
\br_
\bd is substituted. Otherwise, the value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br
1542 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:=
\b=_
\bw_
\bo_
\br_
\bd}
1543 A
\bAs
\bss
\bsi
\big
\bgn
\bn D
\bDe
\bef
\bfa
\bau
\bul
\blt
\bt V
\bVa
\bal
\blu
\bue
\bes
\bs. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is unset or null, the
1544 expansion of _
\bw_
\bo_
\br_
\bd is assigned to _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br. The value of _
\bp_
\ba_
\br_
\ba_
\bm_
\b-
1545 _
\be_
\bt_
\be_
\br is then substituted. Positional parameters and special
1546 parameters may not be assigned to in this way.
1547 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:?
\b?_
\bw_
\bo_
\br_
\bd}
1548 D
\bDi
\bis
\bsp
\bpl
\bla
\bay
\by E
\bEr
\brr
\bro
\bor
\br i
\bif
\bf N
\bNu
\bul
\bll
\bl o
\bor
\br U
\bUn
\bns
\bse
\bet
\bt. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is null or unset,
1549 the expansion of _
\bw_
\bo_
\br_
\bd (or a message to that effect if _
\bw_
\bo_
\br_
\bd is
1550 not present) is written to the standard error and the shell, if
1551 it is not interactive, exits. Otherwise, the value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br
1553 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:+
\b+_
\bw_
\bo_
\br_
\bd}
1554 U
\bUs
\bse
\be A
\bAl
\blt
\bte
\ber
\brn
\bna
\bat
\bte
\be V
\bVa
\bal
\blu
\bue
\be. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is null or unset, nothing is
1555 substituted, otherwise the expansion of _
\bw_
\bo_
\br_
\bd is substituted.
1556 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:_
\bo_
\bf_
\bf_
\bs_
\be_
\bt}
1557 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br:
\b:_
\bo_
\bf_
\bf_
\bs_
\be_
\bt:
\b:_
\bl_
\be_
\bn_
\bg_
\bt_
\bh}
1558 S
\bSu
\bub
\bbs
\bst
\btr
\bri
\bin
\bng
\bg E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn. Expands to up to _
\bl_
\be_
\bn_
\bg_
\bt_
\bh characters of the
1559 value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br starting at the character specified by _
\bo_
\bf_
\bf_
\b-
1560 _
\bs_
\be_
\bt. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@, an indexed array subscripted by @
\b@ or *
\b*,
1561 or an associative array name, the results differ as described
1562 below. If _
\bl_
\be_
\bn_
\bg_
\bt_
\bh is omitted, expands to the substring of the
1563 value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br starting at the character specified by _
\bo_
\bf_
\bf_
\bs_
\be_
\bt
1564 and extending to the end of the value. _
\bl_
\be_
\bn_
\bg_
\bt_
\bh and _
\bo_
\bf_
\bf_
\bs_
\be_
\bt are
1565 arithmetic expressions (see A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN below).
1567 If _
\bo_
\bf_
\bf_
\bs_
\be_
\bt evaluates to a number less than zero, the value is
1568 used as an offset in characters from the end of the value of
1569 _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br. If _
\bl_
\be_
\bn_
\bg_
\bt_
\bh evaluates to a number less than zero, it
1570 is interpreted as an offset in characters from the end of the
1571 value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br rather than a number of characters, and the
1572 expansion is the characters between _
\bo_
\bf_
\bf_
\bs_
\be_
\bt and that result.
1573 Note that a negative offset must be separated from the colon by
1574 at least one space to avoid being confused with the :
\b:-
\b- expan-
1577 If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@, the result is _
\bl_
\be_
\bn_
\bg_
\bt_
\bh positional parameters
1578 beginning at _
\bo_
\bf_
\bf_
\bs_
\be_
\bt. A negative _
\bo_
\bf_
\bf_
\bs_
\be_
\bt is taken relative to one
1579 greater than the greatest positional parameter, so an offset of
1580 -1 evaluates to the last positional parameter. It is an expan-
1581 sion error if _
\bl_
\be_
\bn_
\bg_
\bt_
\bh evaluates to a number less than zero.
1583 If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is an indexed array name subscripted by @ or *, the
1584 result is the _
\bl_
\be_
\bn_
\bg_
\bt_
\bh members of the array beginning with
1585 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br[_
\bo_
\bf_
\bf_
\bs_
\be_
\bt]}. A negative _
\bo_
\bf_
\bf_
\bs_
\be_
\bt is taken relative to
1586 one greater than the maximum index of the specified array. It
1587 is an expansion error if _
\bl_
\be_
\bn_
\bg_
\bt_
\bh evaluates to a number less than
1590 Substring expansion applied to an associative array produces
1593 Substring indexing is zero-based unless the positional parame-
1594 ters are used, in which case the indexing starts at 1 by
1595 default. If _
\bo_
\bf_
\bf_
\bs_
\be_
\bt is 0, and the positional parameters are
1596 used, $
\b$0
\b0 is prefixed to the list.
1598 ${!
\b!_
\bp_
\br_
\be_
\bf_
\bi_
\bx*
\b*}
1599 ${!
\b!_
\bp_
\br_
\be_
\bf_
\bi_
\bx@
\b@}
1600 N
\bNa
\bam
\bme
\bes
\bs m
\bma
\bat
\btc
\bch
\bhi
\bin
\bng
\bg p
\bpr
\bre
\bef
\bfi
\bix
\bx. Expands to the names of variables whose
1601 names begin with _
\bp_
\br_
\be_
\bf_
\bi_
\bx, separated by the first character of the
1602 I
\bIF
\bFS
\bS special variable. When _
\b@ is used and the expansion appears
1603 within double quotes, each variable name expands to a separate
1606 ${!
\b!_
\bn_
\ba_
\bm_
\be[_
\b@]}
1607 ${!
\b!_
\bn_
\ba_
\bm_
\be[_
\b*]}
1608 L
\bLi
\bis
\bst
\bt o
\bof
\bf a
\bar
\brr
\bra
\bay
\by k
\bke
\bey
\bys
\bs. If _
\bn_
\ba_
\bm_
\be is an array variable, expands to
1609 the list of array indices (keys) assigned in _
\bn_
\ba_
\bm_
\be. If _
\bn_
\ba_
\bm_
\be is
1610 not an array, expands to 0 if _
\bn_
\ba_
\bm_
\be is set and null otherwise.
1611 When _
\b@ is used and the expansion appears within double quotes,
1612 each key expands to a separate word.
1614 ${#
\b#_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br}
1615 P
\bPa
\bar
\bra
\bam
\bme
\bet
\bte
\ber
\br l
\ble
\ben
\bng
\bgt
\bth
\bh. The length in characters of the value of
1616 _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is substituted. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is *
\b* or @
\b@, the value
1617 substituted is the number of positional parameters. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\b-
1618 _
\bt_
\be_
\br is an array name subscripted by *
\b* or @
\b@, the value substi-
1619 tuted is the number of elements in the array. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is
1620 an indexed array name subscripted by a negative number, that
1621 number is interpreted as relative to one greater than the maxi-
1622 mum index of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br, so negative indices count back from the
1623 end of the array, and an index of -1 references the last ele-
1626 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br#
\b#_
\bw_
\bo_
\br_
\bd}
1627 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br#
\b##
\b#_
\bw_
\bo_
\br_
\bd}
1628 R
\bRe
\bem
\bmo
\bov
\bve
\be m
\bma
\bat
\btc
\bch
\bhi
\bin
\bng
\bg p
\bpr
\bre
\bef
\bfi
\bix
\bx p
\bpa
\bat
\btt
\bte
\ber
\brn
\bn. The _
\bw_
\bo_
\br_
\bd is expanded to produce
1629 a pattern just as in pathname expansion. If the pattern matches
1630 the beginning of the value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br, then the result of the
1631 expansion is the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br with the shortest
1632 matching pattern (the ``#
\b#'' case) or the longest matching pat-
1633 tern (the ``#
\b##
\b#'' case) deleted. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@ or *
\b*, the
1634 pattern removal operation is applied to each positional parame-
1635 ter in turn, and the expansion is the resultant list. If _
\bp_
\ba_
\br_
\ba_
\bm_
\b-
1636 _
\be_
\bt_
\be_
\br is an array variable subscripted with @
\b@ or *
\b*, the pattern
1637 removal operation is applied to each member of the array in
1638 turn, and the expansion is the resultant list.
1640 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br%
\b%_
\bw_
\bo_
\br_
\bd}
1641 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br%
\b%%
\b%_
\bw_
\bo_
\br_
\bd}
1642 R
\bRe
\bem
\bmo
\bov
\bve
\be m
\bma
\bat
\btc
\bch
\bhi
\bin
\bng
\bg s
\bsu
\buf
\bff
\bfi
\bix
\bx p
\bpa
\bat
\btt
\bte
\ber
\brn
\bn. The _
\bw_
\bo_
\br_
\bd is expanded to produce
1643 a pattern just as in pathname expansion. If the pattern matches
1644 a trailing portion of the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br, then the
1645 result of the expansion is the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br with
1646 the shortest matching pattern (the ``%
\b%'' case) or the longest
1647 matching pattern (the ``%
\b%%
\b%'' case) deleted. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@
1648 or *
\b*, the pattern removal operation is applied to each posi-
1649 tional parameter in turn, and the expansion is the resultant
1650 list. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is an array variable subscripted with @
\b@ or
1651 *
\b*, the pattern removal operation is applied to each member of
1652 the array in turn, and the expansion is the resultant list.
1654 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br/
\b/_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn/
\b/_
\bs_
\bt_
\br_
\bi_
\bn_
\bg}
1655 P
\bPa
\bat
\btt
\bte
\ber
\brn
\bn s
\bsu
\bub
\bbs
\bst
\bti
\bit
\btu
\but
\bti
\bio
\bon
\bn. The _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn is expanded to produce a pat-
1656 tern just as in pathname expansion. _
\bP_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is expanded and
1657 the longest match of _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn against its value is replaced with
1658 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg. If _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn begins with /
\b/, all matches of _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn are
1659 replaced with _
\bs_
\bt_
\br_
\bi_
\bn_
\bg. Normally only the first match is
1660 replaced. If _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn begins with #
\b#, it must match at the begin-
1661 ning of the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br. If _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn begins with
1662 %
\b%, it must match at the end of the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br.
1663 If _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is null, matches of _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn are deleted and the /
\b/ fol-
1664 lowing _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn may be omitted. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@ or *
\b*, the sub-
1665 stitution operation is applied to each positional parameter in
1666 turn, and the expansion is the resultant list. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is
1667 an array variable subscripted with @
\b@ or *
\b*, the substitution
1668 operation is applied to each member of the array in turn, and
1669 the expansion is the resultant list.
1671 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br^
\b^_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn}
1672 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br^
\b^^
\b^_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn}
1673 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br,
\b,_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn}
1674 ${_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br,
\b,,
\b,_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn}
1675 C
\bCa
\bas
\bse
\be m
\bmo
\bod
\bdi
\bif
\bfi
\bic
\bca
\bat
\bti
\bio
\bon
\bn. This expansion modifies the case of alpha-
1676 betic characters in _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br. The _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn is expanded to pro-
1677 duce a pattern just as in pathname expansion. Each character in
1678 the expanded value of _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is tested against _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn, and,
1679 if it matches the pattern, its case is converted. The pattern
1680 should not attempt to match more than one character. The ^
\b^
1681 operator converts lowercase letters matching _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn to upper-
1682 case; the ,
\b, operator converts matching uppercase letters to low-
1683 ercase. The ^
\b^^
\b^ and ,
\b,,
\b, expansions convert each matched character
1684 in the expanded value; the ^
\b^ and ,
\b, expansions match and convert
1685 only the first character in the expanded value. If _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn is
1686 omitted, it is treated like a ?
\b?, which matches every character.
1687 If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is @
\b@ or *
\b*, the case modification operation is
1688 applied to each positional parameter in turn, and the expansion
1689 is the resultant list. If _
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br is an array variable sub-
1690 scripted with @
\b@ or *
\b*, the case modification operation is applied
1691 to each member of the array in turn, and the expansion is the
1694 C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bd S
\bSu
\bub
\bbs
\bst
\bti
\bit
\btu
\but
\bti
\bio
\bon
\bn
1695 _
\bC_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd _
\bs_
\bu_
\bb_
\bs_
\bt_
\bi_
\bt_
\bu_
\bt_
\bi_
\bo_
\bn allows the output of a command to replace the com-
1696 mand name. There are two forms:
1698 $
\b$(
\b(_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd)
\b)
1700 `
\b`_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd`
\b`
1702 B
\bBa
\bas
\bsh
\bh performs the expansion by executing _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd and replacing the com-
1703 mand substitution with the standard output of the command, with any
1704 trailing newlines deleted. Embedded newlines are not deleted, but they
1705 may be removed during word splitting. The command substitution $
\b$(
\b(c
\bca
\bat
\bt
1706 _
\bf_
\bi_
\bl_
\be)
\b) can be replaced by the equivalent but faster $
\b$(
\b(<
\b< _
\bf_
\bi_
\bl_
\be)
\b).
1708 When the old-style backquote form of substitution is used, backslash
1709 retains its literal meaning except when followed by $
\b$, `
\b`, or \
\b\. The
1710 first backquote not preceded by a backslash terminates the command sub-
1711 stitution. When using the $(_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd) form, all characters between the
1712 parentheses make up the command; none are treated specially.
1714 Command substitutions may be nested. To nest when using the backquoted
1715 form, escape the inner backquotes with backslashes.
1717 If the substitution appears within double quotes, word splitting and
1718 pathname expansion are not performed on the results.
1720 A
\bAr
\bri
\bit
\bth
\bhm
\bme
\bet
\bti
\bic
\bc E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
1721 Arithmetic expansion allows the evaluation of an arithmetic expression
1722 and the substitution of the result. The format for arithmetic expan-
1725 $
\b$(
\b((
\b(_
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn)
\b))
\b)
1727 The _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn is treated as if it were within double quotes, but a
1728 double quote inside the parentheses is not treated specially. All
1729 tokens in the expression undergo parameter and variable expansion, com-
1730 mand substitution, and quote removal. The result is treated as the
1731 arithmetic expression to be evaluated. Arithmetic expansions may be
1734 The evaluation is performed according to the rules listed below under
1735 A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN. If _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\bs_
\bi_
\bo_
\bn is invalid, b
\bba
\bas
\bsh
\bh prints a message
1736 indicating failure and no substitution occurs.
1738 P
\bPr
\bro
\boc
\bce
\bes
\bss
\bs S
\bSu
\bub
\bbs
\bst
\bti
\bit
\btu
\but
\bti
\bio
\bon
\bn
1739 _
\bP_
\br_
\bo_
\bc_
\be_
\bs_
\bs _
\bs_
\bu_
\bb_
\bs_
\bt_
\bi_
\bt_
\bu_
\bt_
\bi_
\bo_
\bn is supported on systems that support named pipes
1740 (_
\bF_
\bI_
\bF_
\bO_
\bs) or the /
\b/d
\bde
\bev
\bv/
\b/f
\bfd
\bd method of naming open files. It takes the form
1741 of <
\b<(
\b(_
\bl_
\bi_
\bs_
\bt)
\b) or >
\b>(
\b(_
\bl_
\bi_
\bs_
\bt)
\b). The process _
\bl_
\bi_
\bs_
\bt is run with its input or out-
1742 put connected to a _
\bF_
\bI_
\bF_
\bO or some file in /
\b/d
\bde
\bev
\bv/
\b/f
\bfd
\bd. The name of this file
1743 is passed as an argument to the current command as the result of the
1744 expansion. If the >
\b>(
\b(_
\bl_
\bi_
\bs_
\bt)
\b) form is used, writing to the file will pro-
1745 vide input for _
\bl_
\bi_
\bs_
\bt. If the <
\b<(
\b(_
\bl_
\bi_
\bs_
\bt)
\b) form is used, the file passed as
1746 an argument should be read to obtain the output of _
\bl_
\bi_
\bs_
\bt.
1748 When available, process substitution is performed simultaneously with
1749 parameter and variable expansion, command substitution, and arithmetic
1752 W
\bWo
\bor
\brd
\bd S
\bSp
\bpl
\bli
\bit
\btt
\bti
\bin
\bng
\bg
1753 The shell scans the results of parameter expansion, command substitu-
1754 tion, and arithmetic expansion that did not occur within double quotes
1755 for _
\bw_
\bo_
\br_
\bd _
\bs_
\bp_
\bl_
\bi_
\bt_
\bt_
\bi_
\bn_
\bg.
1757 The shell treats each character of I
\bIF
\bFS
\bS as a delimiter, and splits the
1758 results of the other expansions into words using these characters as
1759 field terminators. If I
\bIF
\bFS
\bS is unset, or its value is exactly
1760 <
\b<s
\bsp
\bpa
\bac
\bce
\be>
\b><
\b<t
\bta
\bab
\bb>
\b><
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b>, the default, then sequences of <
\b<s
\bsp
\bpa
\bac
\bce
\be>
\b>, <
\b<t
\bta
\bab
\bb>
\b>,
1761 and <
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b> at the beginning and end of the results of the previous
1762 expansions are ignored, and any sequence of I
\bIF
\bFS
\bS characters not at the
1763 beginning or end serves to delimit words. If I
\bIF
\bFS
\bS has a value other
1764 than the default, then sequences of the whitespace characters s
\bsp
\bpa
\bac
\bce
\be and
1765 t
\bta
\bab
\bb are ignored at the beginning and end of the word, as long as the
1766 whitespace character is in the value of I
\bIF
\bFS
\bS (an I
\bIF
\bFS
\bS whitespace charac-
1767 ter). Any character in I
\bIF
\bFS
\bS that is not I
\bIF
\bFS
\bS whitespace, along with any
1768 adjacent I
\bIF
\bFS
\bS whitespace characters, delimits a field. A sequence of
1769 I
\bIF
\bFS
\bS whitespace characters is also treated as a delimiter. If the value
1770 of I
\bIF
\bFS
\bS is null, no word splitting occurs.
1772 Explicit null arguments ("
\b""
\b" or '
\b''
\b') are retained. Unquoted implicit
1773 null arguments, resulting from the expansion of parameters that have no
1774 values, are removed. If a parameter with no value is expanded within
1775 double quotes, a null argument results and is retained.
1777 Note that if no expansion occurs, no splitting is performed.
1779 P
\bPa
\bat
\bth
\bhn
\bna
\bam
\bme
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
1780 After word splitting, unless the -
\b-f
\bf option has been set, b
\bba
\bas
\bsh
\bh scans
1781 each word for the characters *
\b*, ?
\b?, and [
\b[. If one of these characters
1782 appears, then the word is regarded as a _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn, and replaced with an
1783 alphabetically sorted list of filenames matching the pattern (see P
\bPa
\bat
\bt-
\b-
1784 t
\bte
\ber
\brn
\bn M
\bMa
\bat
\btc
\bch
\bhi
\bin
\bng
\bg below). If no matching filenames are found, and the
1785 shell option n
\bnu
\bul
\bll
\blg
\bgl
\blo
\bob
\bb is not enabled, the word is left unchanged. If
1786 the n
\bnu
\bul
\bll
\blg
\bgl
\blo
\bob
\bb option is set, and no matches are found, the word is
1787 removed. If the f
\bfa
\bai
\bil
\blg
\bgl
\blo
\bob
\bb shell option is set, and no matches are
1788 found, an error message is printed and the command is not executed. If
1789 the shell option n
\bno
\boc
\bca
\bas
\bse
\beg
\bgl
\blo
\bob
\bb is enabled, the match is performed without
1790 regard to the case of alphabetic characters. When a pattern is used
1791 for pathname expansion, the character `
\b``
\b`.
\b.'
\b''
\b' at the start of a name or
1792 immediately following a slash must be matched explicitly, unless the
1793 shell option d
\bdo
\bot
\btg
\bgl
\blo
\bob
\bb is set. When matching a pathname, the slash char-
1794 acter must always be matched explicitly. In other cases, the `
\b``
\b`.
\b.'
\b''
\b'
1795 character is not treated specially. See the description of s
\bsh
\bho
\bop
\bpt
\bt below
1796 under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS for a description of the n
\bno
\boc
\bca
\bas
\bse
\beg
\bgl
\blo
\bob
\bb, n
\bnu
\bul
\bll
\bl-
\b-
1797 g
\bgl
\blo
\bob
\bb, f
\bfa
\bai
\bil
\blg
\bgl
\blo
\bob
\bb, and d
\bdo
\bot
\btg
\bgl
\blo
\bob
\bb shell options.
1799 The G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE shell variable may be used to restrict the set of file-
1800 names matching a _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn. If G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is set, each matching filename
1801 that also matches one of the patterns in G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is removed from the
1802 list of matches. The filenames `
\b``
\b`.
\b.'
\b''
\b' and `
\b``
\b`.
\b..
\b.'
\b''
\b' are always ignored
1803 when G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is set and not null. However, setting G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE to a
1804 non-null value has the effect of enabling the d
\bdo
\bot
\btg
\bgl
\blo
\bob
\bb shell option, so
1805 all other filenames beginning with a `
\b``
\b`.
\b.'
\b''
\b' will match. To get the old
1806 behavior of ignoring filenames beginning with a `
\b``
\b`.
\b.'
\b''
\b', make `
\b``
\b`.
\b.*
\b*'
\b''
\b' one
1807 of the patterns in G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE. The d
\bdo
\bot
\btg
\bgl
\blo
\bob
\bb option is disabled when
1808 G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is unset.
1810 P
\bPa
\bat
\btt
\bte
\ber
\brn
\bn M
\bMa
\bat
\btc
\bch
\bhi
\bin
\bng
\bg
1812 Any character that appears in a pattern, other than the special pattern
1813 characters described below, matches itself. The NUL character may not
1814 occur in a pattern. A backslash escapes the following character; the
1815 escaping backslash is discarded when matching. The special pattern
1816 characters must be quoted if they are to be matched literally.
1818 The special pattern characters have the following meanings:
1820 *
\b* Matches any string, including the null string. When the
1821 g
\bgl
\blo
\bob
\bbs
\bst
\bta
\bar
\br shell option is enabled, and *
\b* is used in a
1822 pathname expansion context, two adjacent *
\b*s used as a
1823 single pattern will match all files and zero or more
1824 directories and subdirectories. If followed by a /
\b/, two
1825 adjacent *
\b*s will match only directories and subdirecto-
1827 ?
\b? Matches any single character.
1828 [
\b[.
\b..
\b..
\b.]
\b] Matches any one of the enclosed characters. A pair of
1829 characters separated by a hyphen denotes a _
\br_
\ba_
\bn_
\bg_
\be _
\be_
\bx_
\bp_
\br_
\be_
\bs_
\b-
1830 _
\bs_
\bi_
\bo_
\bn; any character that falls between those two charac-
1831 ters, inclusive, using the current locale's collating
1832 sequence and character set, is matched. If the first
1833 character following the [
\b[ is a !
\b! or a ^
\b^ then any charac-
1834 ter not enclosed is matched. The sorting order of char-
1835 acters in range expressions is determined by the current
1836 locale and the values of the L
\bLC
\bC_
\b_C
\bCO
\bOL
\bLL
\bLA
\bAT
\bTE
\bE or L
\bLC
\bC_
\b_A
\bAL
\bLL
\bL shell
1837 variables, if set. To obtain the traditional interpreta-
1838 tion of range expressions, where [
\b[a
\ba-
\b-d
\bd]
\b] is equivalent to
1839 [
\b[a
\bab
\bbc
\bcd
\bd]
\b], set value of the L
\bLC
\bC_
\b_A
\bAL
\bLL
\bL shell variable to C
\bC, or
1840 enable the g
\bgl
\blo
\bob
\bba
\bas
\bsc
\bci
\bii
\bir
\bra
\ban
\bng
\bge
\bes
\bs shell option. A -
\b- may be
1841 matched by including it as the first or last character in
1842 the set. A ]
\b] may be matched by including it as the first
1843 character in the set.
1845 Within [
\b[ and ]
\b], _
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br _
\bc_
\bl_
\ba_
\bs_
\bs_
\be_
\bs can be specified using
1846 the syntax [
\b[:
\b:_
\bc_
\bl_
\ba_
\bs_
\bs:
\b:]
\b], where _
\bc_
\bl_
\ba_
\bs_
\bs is one of the following
1847 classes defined in the POSIX standard:
1848 a
\bal
\bln
\bnu
\bum
\bm a
\bal
\blp
\bph
\bha
\ba a
\bas
\bsc
\bci
\bii
\bi b
\bbl
\bla
\ban
\bnk
\bk c
\bcn
\bnt
\btr
\brl
\bl d
\bdi
\big
\bgi
\bit
\bt g
\bgr
\bra
\bap
\bph
\bh l
\blo
\bow
\bwe
\ber
\br p
\bpr
\bri
\bin
\bnt
\bt
1849 p
\bpu
\bun
\bnc
\bct
\bt s
\bsp
\bpa
\bac
\bce
\be u
\bup
\bpp
\bpe
\ber
\br w
\bwo
\bor
\brd
\bd x
\bxd
\bdi
\big
\bgi
\bit
\bt
1850 A character class matches any character belonging to that
1851 class. The w
\bwo
\bor
\brd
\bd character class matches letters, digits,
1852 and the character _.
1854 Within [
\b[ and ]
\b], an _
\be_
\bq_
\bu_
\bi_
\bv_
\ba_
\bl_
\be_
\bn_
\bc_
\be _
\bc_
\bl_
\ba_
\bs_
\bs can be specified
1855 using the syntax [
\b[=
\b=_
\bc=
\b=]
\b], which matches all characters with
1856 the same collation weight (as defined by the current
1857 locale) as the character _
\bc.
1859 Within [
\b[ and ]
\b], the syntax [
\b[.
\b._
\bs_
\by_
\bm_
\bb_
\bo_
\bl.
\b.]
\b] matches the collat-
1860 ing symbol _
\bs_
\by_
\bm_
\bb_
\bo_
\bl.
1862 If the e
\bex
\bxt
\btg
\bgl
\blo
\bob
\bb shell option is enabled using the s
\bsh
\bho
\bop
\bpt
\bt builtin, several
1863 extended pattern matching operators are recognized. In the following
1864 description, a _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt is a list of one or more patterns separated
1865 by a |
\b|. Composite patterns may be formed using one or more of the fol-
1866 lowing sub-patterns:
1868 ?
\b?(
\b(_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt)
\b)
1869 Matches zero or one occurrence of the given patterns
1870 *
\b*(
\b(_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt)
\b)
1871 Matches zero or more occurrences of the given patterns
1872 +
\b+(
\b(_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt)
\b)
1873 Matches one or more occurrences of the given patterns
1874 @
\b@(
\b(_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt)
\b)
1875 Matches one of the given patterns
1876 !
\b!(
\b(_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn_
\b-_
\bl_
\bi_
\bs_
\bt)
\b)
1877 Matches anything except one of the given patterns
1879 Q
\bQu
\buo
\bot
\bte
\be R
\bRe
\bem
\bmo
\bov
\bva
\bal
\bl
1880 After the preceding expansions, all unquoted occurrences of the charac-
1881 ters \
\b\, '
\b', and "
\b" that did not result from one of the above expansions
1884 R
\bRE
\bED
\bDI
\bIR
\bRE
\bEC
\bCT
\bTI
\bIO
\bON
\bN
1885 Before a command is executed, its input and output may be _
\br_
\be_
\bd_
\bi_
\br_
\be_
\bc_
\bt_
\be_
\bd
1886 using a special notation interpreted by the shell. Redirection allows
1887 commands' file handles to be duplicated, opened, closed, made to refer
1888 to different files, and can change the files the command reads from and
1889 writes to. Redirection may also be used to modify file handles in the
1890 current shell execution environment. The following redirection opera-
1891 tors may precede or appear anywhere within a _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd or may fol-
1892 low a _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd. Redirections are processed in the order they appear,
1895 Each redirection that may be preceded by a file descriptor number may
1896 instead be preceded by a word of the form {_
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be}. In this case, for
1897 each redirection operator except >&- and <&-, the shell will allocate a
1898 file descriptor greater than or equal to 10 and assign it to _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be.
1899 If >&- or <&- is preceded by {_
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be}, the value of _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be defines
1900 the file descriptor to close.
1902 In the following descriptions, if the file descriptor number is omit-
1903 ted, and the first character of the redirection operator is <
\b<, the re-
1904 direction refers to the standard input (file descriptor 0). If the
1905 first character of the redirection operator is >
\b>, the redirection
1906 refers to the standard output (file descriptor 1).
1908 The word following the redirection operator in the following descrip-
1909 tions, unless otherwise noted, is subjected to brace expansion, tilde
1910 expansion, parameter and variable expansion, command substitution,
1911 arithmetic expansion, quote removal, pathname expansion, and word
1912 splitting. If it expands to more than one word, b
\bba
\bas
\bsh
\bh reports an error.
1914 Note that the order of redirections is significant. For example, the
1917 ls >
\b> dirlist 2>
\b>&
\b&1
1919 directs both standard output and standard error to the file _
\bd_
\bi_
\br_
\bl_
\bi_
\bs_
\bt,
1922 ls 2>
\b>&
\b&1 >
\b> dirlist
1924 directs only the standard output to file _
\bd_
\bi_
\br_
\bl_
\bi_
\bs_
\bt, because the standard
1925 error was duplicated from the standard output before the standard out-
1926 put was redirected to _
\bd_
\bi_
\br_
\bl_
\bi_
\bs_
\bt.
1928 B
\bBa
\bas
\bsh
\bh handles several filenames specially when they are used in redirec-
1929 tions, as described in the following table:
1931 /
\b/d
\bde
\bev
\bv/
\b/f
\bfd
\bd/
\b/_
\bf_
\bd
1932 If _
\bf_
\bd is a valid integer, file descriptor _
\bf_
\bd is dupli-
1934 /
\b/d
\bde
\bev
\bv/
\b/s
\bst
\btd
\bdi
\bin
\bn
1935 File descriptor 0 is duplicated.
1936 /
\b/d
\bde
\bev
\bv/
\b/s
\bst
\btd
\bdo
\bou
\but
\bt
1937 File descriptor 1 is duplicated.
1938 /
\b/d
\bde
\bev
\bv/
\b/s
\bst
\btd
\bde
\ber
\brr
\br
1939 File descriptor 2 is duplicated.
1940 /
\b/d
\bde
\bev
\bv/
\b/t
\btc
\bcp
\bp/
\b/_
\bh_
\bo_
\bs_
\bt/
\b/_
\bp_
\bo_
\br_
\bt
1941 If _
\bh_
\bo_
\bs_
\bt is a valid hostname or Internet address, and _
\bp_
\bo_
\br_
\bt
1942 is an integer port number or service name, b
\bba
\bas
\bsh
\bh attempts
1943 to open the corresponding TCP socket.
1944 /
\b/d
\bde
\bev
\bv/
\b/u
\bud
\bdp
\bp/
\b/_
\bh_
\bo_
\bs_
\bt/
\b/_
\bp_
\bo_
\br_
\bt
1945 If _
\bh_
\bo_
\bs_
\bt is a valid hostname or Internet address, and _
\bp_
\bo_
\br_
\bt
1946 is an integer port number or service name, b
\bba
\bas
\bsh
\bh attempts
1947 to open the corresponding UDP socket.
1949 A failure to open or create a file causes the redirection to fail.
1951 Redirections using file descriptors greater than 9 should be used with
1952 care, as they may conflict with file descriptors the shell uses inter-
1955 R
\bRe
\bed
\bdi
\bir
\bre
\bec
\bct
\bti
\bin
\bng
\bg I
\bIn
\bnp
\bpu
\but
\bt
1956 Redirection of input causes the file whose name results from the expan-
1957 sion of _
\bw_
\bo_
\br_
\bd to be opened for reading on file descriptor _
\bn, or the
1958 standard input (file descriptor 0) if _
\bn is not specified.
1960 The general format for redirecting input is:
1962 [_
\bn]<
\b<_
\bw_
\bo_
\br_
\bd
1964 R
\bRe
\bed
\bdi
\bir
\bre
\bec
\bct
\bti
\bin
\bng
\bg O
\bOu
\but
\btp
\bpu
\but
\bt
1965 Redirection of output causes the file whose name results from the
1966 expansion of _
\bw_
\bo_
\br_
\bd to be opened for writing on file descriptor _
\bn, or the
1967 standard output (file descriptor 1) if _
\bn is not specified. If the file
1968 does not exist it is created; if it does exist it is truncated to zero
1971 The general format for redirecting output is:
1973 [_
\bn]>
\b>_
\bw_
\bo_
\br_
\bd
1975 If the redirection operator is >
\b>, and the n
\bno
\boc
\bcl
\blo
\bob
\bbb
\bbe
\ber
\br option to the s
\bse
\bet
\bt
1976 builtin has been enabled, the redirection will fail if the file whose
1977 name results from the expansion of _
\bw_
\bo_
\br_
\bd exists and is a regular file.
1978 If the redirection operator is >
\b>|
\b|, or the redirection operator is >
\b> and
1979 the n
\bno
\boc
\bcl
\blo
\bob
\bbb
\bbe
\ber
\br option to the s
\bse
\bet
\bt builtin command is not enabled, the re-
1980 direction is attempted even if the file named by _
\bw_
\bo_
\br_
\bd exists.
1982 A
\bAp
\bpp
\bpe
\ben
\bnd
\bdi
\bin
\bng
\bg R
\bRe
\bed
\bdi
\bir
\bre
\bec
\bct
\bte
\bed
\bd O
\bOu
\but
\btp
\bpu
\but
\bt
1983 Redirection of output in this fashion causes the file whose name
1984 results from the expansion of _
\bw_
\bo_
\br_
\bd to be opened for appending on file
1985 descriptor _
\bn, or the standard output (file descriptor 1) if _
\bn is not
1986 specified. If the file does not exist it is created.
1988 The general format for appending output is:
1990 [_
\bn]>
\b>>
\b>_
\bw_
\bo_
\br_
\bd
1993 R
\bRe
\bed
\bdi
\bir
\bre
\bec
\bct
\bti
\bin
\bng
\bg S
\bSt
\bta
\ban
\bnd
\bda
\bar
\brd
\bd O
\bOu
\but
\btp
\bpu
\but
\bt a
\ban
\bnd
\bd S
\bSt
\bta
\ban
\bnd
\bda
\bar
\brd
\bd E
\bEr
\brr
\bro
\bor
\br
1994 This construct allows both the standard output (file descriptor 1) and
1995 the standard error output (file descriptor 2) to be redirected to the
1996 file whose name is the expansion of _
\bw_
\bo_
\br_
\bd.
1998 There are two formats for redirecting standard output and standard
2001 &
\b&>
\b>_
\bw_
\bo_
\br_
\bd
2003 >
\b>&
\b&_
\bw_
\bo_
\br_
\bd
2005 Of the two forms, the first is preferred. This is semantically equiva-
2008 >
\b>_
\bw_
\bo_
\br_
\bd 2>
\b>&
\b&1
2010 When using the second form, _
\bw_
\bo_
\br_
\bd may not expand to a number or -
\b-. If
2011 it does, other redirection operators apply (see D
\bDu
\bup
\bpl
\bli
\bic
\bca
\bat
\bti
\bin
\bng
\bg F
\bFi
\bil
\ble
\be
2012 D
\bDe
\bes
\bsc
\bcr
\bri
\bip
\bpt
\bto
\bor
\brs
\bs below) for compatibility reasons.
2014 A
\bAp
\bpp
\bpe
\ben
\bnd
\bdi
\bin
\bng
\bg S
\bSt
\bta
\ban
\bnd
\bda
\bar
\brd
\bd O
\bOu
\but
\btp
\bpu
\but
\bt a
\ban
\bnd
\bd S
\bSt
\bta
\ban
\bnd
\bda
\bar
\brd
\bd E
\bEr
\brr
\bro
\bor
\br
2015 This construct allows both the standard output (file descriptor 1) and
2016 the standard error output (file descriptor 2) to be appended to the
2017 file whose name is the expansion of _
\bw_
\bo_
\br_
\bd.
2019 The format for appending standard output and standard error is:
2021 &
\b&>
\b>>
\b>_
\bw_
\bo_
\br_
\bd
2023 This is semantically equivalent to
2025 >
\b>>
\b>_
\bw_
\bo_
\br_
\bd 2>
\b>&
\b&1
2027 (see D
\bDu
\bup
\bpl
\bli
\bic
\bca
\bat
\bti
\bin
\bng
\bg F
\bFi
\bil
\ble
\be D
\bDe
\bes
\bsc
\bcr
\bri
\bip
\bpt
\bto
\bor
\brs
\bs below).
2029 H
\bHe
\ber
\bre
\be D
\bDo
\boc
\bcu
\bum
\bme
\ben
\bnt
\bts
\bs
2030 This type of redirection instructs the shell to read input from the
2031 current source until a line containing only _
\bd_
\be_
\bl_
\bi_
\bm_
\bi_
\bt_
\be_
\br (with no trailing
2032 blanks) is seen. All of the lines read up to that point are then used
2033 as the standard input for a command.
2035 The format of here-documents is:
2037 <
\b<<
\b<[-
\b-]_
\bw_
\bo_
\br_
\bd
2038 _
\bh_
\be_
\br_
\be_
\b-_
\bd_
\bo_
\bc_
\bu_
\bm_
\be_
\bn_
\bt
2039 _
\bd_
\be_
\bl_
\bi_
\bm_
\bi_
\bt_
\be_
\br
2041 No parameter and variable expansion, command substitution, arithmetic
2042 expansion, or pathname expansion is performed on _
\bw_
\bo_
\br_
\bd. If any charac-
2043 ters in _
\bw_
\bo_
\br_
\bd are quoted, the _
\bd_
\be_
\bl_
\bi_
\bm_
\bi_
\bt_
\be_
\br is the result of quote removal
2044 on _
\bw_
\bo_
\br_
\bd, and the lines in the here-document are not expanded. If _
\bw_
\bo_
\br_
\bd
2045 is unquoted, all lines of the here-document are subjected to parameter
2046 expansion, command substitution, and arithmetic expansion, the charac-
2047 ter sequence \
\b\<
\b<n
\bne
\bew
\bwl
\bli
\bin
\bne
\be>
\b> is ignored, and \
\b\ must be used to quote the
2048 characters \
\b\, $
\b$, and `
\b`.
2050 If the redirection operator is <
\b<<
\b<-
\b-, then all leading tab characters are
2051 stripped from input lines and the line containing _
\bd_
\be_
\bl_
\bi_
\bm_
\bi_
\bt_
\be_
\br. This
2052 allows here-documents within shell scripts to be indented in a natural
2055 H
\bHe
\ber
\bre
\be S
\bSt
\btr
\bri
\bin
\bng
\bgs
\bs
2056 A variant of here documents, the format is:
2058 <
\b<<
\b<<
\b<_
\bw_
\bo_
\br_
\bd
2060 The _
\bw_
\bo_
\br_
\bd undergoes brace expansion, tilde expansion, parameter and
2061 variable expansion, command substitution, arithmetic expansion, and
2062 quote removal. Pathname expansion and word splitting are not per-
2063 formed. The result is supplied as a single string to the command on
2066 D
\bDu
\bup
\bpl
\bli
\bic
\bca
\bat
\bti
\bin
\bng
\bg F
\bFi
\bil
\ble
\be D
\bDe
\bes
\bsc
\bcr
\bri
\bip
\bpt
\bto
\bor
\brs
\bs
2067 The redirection operator
2069 [_
\bn]<
\b<&
\b&_
\bw_
\bo_
\br_
\bd
2071 is used to duplicate input file descriptors. If _
\bw_
\bo_
\br_
\bd expands to one or
2072 more digits, the file descriptor denoted by _
\bn is made to be a copy of
2073 that file descriptor. If the digits in _
\bw_
\bo_
\br_
\bd do not specify a file
2074 descriptor open for input, a redirection error occurs. If _
\bw_
\bo_
\br_
\bd evalu-
2075 ates to -
\b-, file descriptor _
\bn is closed. If _
\bn is not specified, the
2076 standard input (file descriptor 0) is used.
2080 [_
\bn]>
\b>&
\b&_
\bw_
\bo_
\br_
\bd
2082 is used similarly to duplicate output file descriptors. If _
\bn is not
2083 specified, the standard output (file descriptor 1) is used. If the
2084 digits in _
\bw_
\bo_
\br_
\bd do not specify a file descriptor open for output, a re-
2085 direction error occurs. If _
\bw_
\bo_
\br_
\bd evaluates to -
\b-, file descriptor _
\bn is
2086 closed. As a special case, if _
\bn is omitted, and _
\bw_
\bo_
\br_
\bd does not expand
2087 to one or more digits or -
\b-, the standard output and standard error are
2088 redirected as described previously.
2090 M
\bMo
\bov
\bvi
\bin
\bng
\bg F
\bFi
\bil
\ble
\be D
\bDe
\bes
\bsc
\bcr
\bri
\bip
\bpt
\bto
\bor
\brs
\bs
2091 The redirection operator
2093 [_
\bn]<
\b<&
\b&_
\bd_
\bi_
\bg_
\bi_
\bt-
\b-
2095 moves the file descriptor _
\bd_
\bi_
\bg_
\bi_
\bt to file descriptor _
\bn, or the standard
2096 input (file descriptor 0) if _
\bn is not specified. _
\bd_
\bi_
\bg_
\bi_
\bt is closed after
2097 being duplicated to _
\bn.
2099 Similarly, the redirection operator
2101 [_
\bn]>
\b>&
\b&_
\bd_
\bi_
\bg_
\bi_
\bt-
\b-
2103 moves the file descriptor _
\bd_
\bi_
\bg_
\bi_
\bt to file descriptor _
\bn, or the standard
2104 output (file descriptor 1) if _
\bn is not specified.
2106 O
\bOp
\bpe
\ben
\bni
\bin
\bng
\bg F
\bFi
\bil
\ble
\be D
\bDe
\bes
\bsc
\bcr
\bri
\bip
\bpt
\bto
\bor
\brs
\bs f
\bfo
\bor
\br R
\bRe
\bea
\bad
\bdi
\bin
\bng
\bg a
\ban
\bnd
\bd W
\bWr
\bri
\bit
\bti
\bin
\bng
\bg
2107 The redirection operator
2109 [_
\bn]<
\b<>
\b>_
\bw_
\bo_
\br_
\bd
2111 causes the file whose name is the expansion of _
\bw_
\bo_
\br_
\bd to be opened for
2112 both reading and writing on file descriptor _
\bn, or on file descriptor 0
2113 if _
\bn is not specified. If the file does not exist, it is created.
2115 A
\bAL
\bLI
\bIA
\bAS
\bSE
\bES
\bS
2116 _
\bA_
\bl_
\bi_
\ba_
\bs_
\be_
\bs allow a string to be substituted for a word when it is used as
2117 the first word of a simple command. The shell maintains a list of
2118 aliases that may be set and unset with the a
\bal
\bli
\bia
\bas
\bs and u
\bun
\bna
\bal
\bli
\bia
\bas
\bs builtin
2119 commands (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). The first word of each
2120 simple command, if unquoted, is checked to see if it has an alias. If
2121 so, that word is replaced by the text of the alias. The characters /
\b/,
2122 $
\b$, `
\b`, and =
\b= and any of the shell _
\bm_
\be_
\bt_
\ba_
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br_
\bs or quoting characters
2123 listed above may not appear in an alias name. The replacement text may
2124 contain any valid shell input, including shell metacharacters. The
2125 first word of the replacement text is tested for aliases, but a word
2126 that is identical to an alias being expanded is not expanded a second
2127 time. This means that one may alias l
\bls
\bs to l
\bls
\bs -
\b-F
\bF, for instance, and
2128 b
\bba
\bas
\bsh
\bh does not try to recursively expand the replacement text. If the
2129 last character of the alias value is a _
\bb_
\bl_
\ba_
\bn_
\bk, then the next command
2130 word following the alias is also checked for alias expansion.
2132 Aliases are created and listed with the a
\bal
\bli
\bia
\bas
\bs command, and removed with
2133 the u
\bun
\bna
\bal
\bli
\bia
\bas
\bs command.
2135 There is no mechanism for using arguments in the replacement text. If
2136 arguments are needed, a shell function should be used (see F
\bFU
\bUN
\bNC
\bCT
\bTI
\bIO
\bON
\bNS
\bS
2139 Aliases are not expanded when the shell is not interactive, unless the
2140 e
\bex
\bxp
\bpa
\ban
\bnd
\bd_
\b_a
\bal
\bli
\bia
\bas
\bse
\bes
\bs shell option is set using s
\bsh
\bho
\bop
\bpt
\bt (see the description of
2141 s
\bsh
\bho
\bop
\bpt
\bt under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
2143 The rules concerning the definition and use of aliases are somewhat
2144 confusing. B
\bBa
\bas
\bsh
\bh always reads at least one complete line of input
2145 before executing any of the commands on that line. Aliases are
2146 expanded when a command is read, not when it is executed. Therefore,
2147 an alias definition appearing on the same line as another command does
2148 not take effect until the next line of input is read. The commands
2149 following the alias definition on that line are not affected by the new
2150 alias. This behavior is also an issue when functions are executed.
2151 Aliases are expanded when a function definition is read, not when the
2152 function is executed, because a function definition is itself a com-
2153 pound command. As a consequence, aliases defined in a function are not
2154 available until after that function is executed. To be safe, always
2155 put alias definitions on a separate line, and do not use a
\bal
\bli
\bia
\bas
\bs in com-
2158 For almost every purpose, aliases are superseded by shell functions.
2160 F
\bFU
\bUN
\bNC
\bCT
\bTI
\bIO
\bON
\bNS
\bS
2161 A shell function, defined as described above under S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR,
2162 stores a series of commands for later execution. When the name of a
2163 shell function is used as a simple command name, the list of commands
2164 associated with that function name is executed. Functions are executed
2165 in the context of the current shell; no new process is created to
2166 interpret them (contrast this with the execution of a shell script).
2167 When a function is executed, the arguments to the function become the
2168 positional parameters during its execution. The special parameter #
\b# is
2169 updated to reflect the change. Special parameter 0
\b0 is unchanged. The
2170 first element of the F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE variable is set to the name of the func-
2171 tion while the function is executing.
2173 All other aspects of the shell execution environment are identical
2174 between a function and its caller with these exceptions: the D
\bDE
\bEB
\bBU
\bUG
\bG and
2175 R
\bRE
\bET
\bTU
\bUR
\bRN
\bN traps (see the description of the t
\btr
\bra
\bap
\bp builtin under S
\bSH
\bHE
\bEL
\bLL
\bL
2176 B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below) are not inherited unless the function has been
2177 given the t
\btr
\bra
\bac
\bce
\be attribute (see the description of the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin
2178 below) or the -
\b-o
\bo f
\bfu
\bun
\bnc
\bct
\btr
\bra
\bac
\bce
\be shell option has been enabled with the s
\bse
\bet
\bt
2179 builtin (in which case all functions inherit the D
\bDE
\bEB
\bBU
\bUG
\bG and R
\bRE
\bET
\bTU
\bUR
\bRN
\bN
2180 traps), and the E
\bER
\bRR
\bR trap is not inherited unless the -
\b-o
\bo e
\ber
\brr
\brt
\btr
\bra
\bac
\bce
\be shell
2181 option has been enabled.
2183 Variables local to the function may be declared with the l
\blo
\boc
\bca
\bal
\bl builtin
2184 command. Ordinarily, variables and their values are shared between the
2185 function and its caller.
2187 The F
\bFU
\bUN
\bNC
\bCN
\bNE
\bES
\bST
\bT variable, if set to a numeric value greater than 0,
2188 defines a maximum function nesting level. Function invocations that
2189 exceed the limit cause the entire command to abort.
2191 If the builtin command r
\bre
\bet
\btu
\bur
\brn
\bn is executed in a function, the function
2192 completes and execution resumes with the next command after the func-
2193 tion call. Any command associated with the R
\bRE
\bET
\bTU
\bUR
\bRN
\bN trap is executed
2194 before execution resumes. When a function completes, the values of the
2195 positional parameters and the special parameter #
\b# are restored to the
2196 values they had prior to the function's execution.
2198 Function names and definitions may be listed with the -
\b-f
\bf option to the
2199 d
\bde
\bec
\bcl
\bla
\bar
\bre
\be or t
\bty
\byp
\bpe
\bes
\bse
\bet
\bt builtin commands. The -
\b-F
\bF option to d
\bde
\bec
\bcl
\bla
\bar
\bre
\be or t
\bty
\byp
\bpe
\be-
\b-
2200 s
\bse
\bet
\bt will list the function names only (and optionally the source file
2201 and line number, if the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg shell option is enabled). Functions
2202 may be exported so that subshells automatically have them defined with
2203 the -
\b-f
\bf option to the e
\bex
\bxp
\bpo
\bor
\brt
\bt builtin. A function definition may be
2204 deleted using the -
\b-f
\bf option to the u
\bun
\bns
\bse
\bet
\bt builtin. Note that shell
2205 functions and variables with the same name may result in multiple iden-
2206 tically-named entries in the environment passed to the shell's chil-
2207 dren. Care should be taken in cases where this may cause a problem.
2209 Functions may be recursive. The F
\bFU
\bUN
\bNC
\bCN
\bNE
\bES
\bST
\bT variable may be used to limit
2210 the depth of the function call stack and restrict the number of func-
2211 tion invocations. By default, no limit is imposed on the number of
2214 A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN
2215 The shell allows arithmetic expressions to be evaluated, under certain
2216 circumstances (see the l
\ble
\bet
\bt and d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin commands and A
\bAr
\bri
\bit
\bth
\bhm
\bme
\bet
\bti
\bic
\bc
2217 E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn). Evaluation is done in fixed-width integers with no check
2218 for overflow, though division by 0 is trapped and flagged as an error.
2219 The operators and their precedence, associativity, and values are the
2220 same as in the C language. The following list of operators is grouped
2221 into levels of equal-precedence operators. The levels are listed in
2222 order of decreasing precedence.
2224 _
\bi_
\bd+
\b++
\b+ _
\bi_
\bd-
\b--
\b-
2225 variable post-increment and post-decrement
2226 +
\b++
\b+_
\bi_
\bd -
\b--
\b-_
\bi_
\bd
2227 variable pre-increment and pre-decrement
2228 -
\b- +
\b+ unary minus and plus
2229 !
\b! ~
\b~ logical and bitwise negation
2230 *
\b**
\b* exponentiation
2231 *
\b* /
\b/ %
\b% multiplication, division, remainder
2232 +
\b+ -
\b- addition, subtraction
2233 <
\b<<
\b< >
\b>>
\b> left and right bitwise shifts
2234 <
\b<=
\b= >
\b>=
\b= <
\b< >
\b>
2236 =
\b==
\b= !
\b!=
\b= equality and inequality
2238 ^
\b^ bitwise exclusive OR
2240 &
\b&&
\b& logical AND
2242 _
\be_
\bx_
\bp_
\br?
\b?_
\be_
\bx_
\bp_
\br:
\b:_
\be_
\bx_
\bp_
\br
2243 conditional operator
2244 =
\b= *
\b*=
\b= /
\b/=
\b= %
\b%=
\b= +
\b+=
\b= -
\b-=
\b= <
\b<<
\b<=
\b= >
\b>>
\b>=
\b= &
\b&=
\b= ^
\b^=
\b= |
\b|=
\b=
2246 _
\be_
\bx_
\bp_
\br_
\b1 ,
\b, _
\be_
\bx_
\bp_
\br_
\b2
2249 Shell variables are allowed as operands; parameter expansion is per-
2250 formed before the expression is evaluated. Within an expression, shell
2251 variables may also be referenced by name without using the parameter
2252 expansion syntax. A shell variable that is null or unset evaluates to
2253 0 when referenced by name without using the parameter expansion syntax.
2254 The value of a variable is evaluated as an arithmetic expression when
2255 it is referenced, or when a variable which has been given the _
\bi_
\bn_
\bt_
\be_
\bg_
\be_
\br
2256 attribute using d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-i
\bi is assigned a value. A null value evaluates
2257 to 0. A shell variable need not have its _
\bi_
\bn_
\bt_
\be_
\bg_
\be_
\br attribute turned on
2258 to be used in an expression.
2260 Constants with a leading 0 are interpreted as octal numbers. A leading
2261 0x or 0X denotes hexadecimal. Otherwise, numbers take the form
2262 [_
\bb_
\ba_
\bs_
\be_
\b#]n, where the optional _
\bb_
\ba_
\bs_
\be is a decimal number between 2 and 64
2263 representing the arithmetic base, and _
\bn is a number in that base. If
2264 _
\bb_
\ba_
\bs_
\be_
\b# is omitted, then base 10 is used. When specifying _
\bn, the digits
2265 greater< than 9 are represented by the lowercase letters, the uppercase
2266 letters, @, and _, in that order. If _
\bb_
\ba_
\bs_
\be is less than or equal to 36,
2267 lowercase and uppercase letters may be used interchangeably to repre-
2268 sent numbers between 10 and 35.
2270 Operators are evaluated in order of precedence. Sub-expressions in
2271 parentheses are evaluated first and may override the precedence rules
2274 C
\bCO
\bON
\bND
\bDI
\bIT
\bTI
\bIO
\bON
\bNA
\bAL
\bL E
\bEX
\bXP
\bPR
\bRE
\bES
\bSS
\bSI
\bIO
\bON
\bNS
\bS
2275 Conditional expressions are used by the [
\b[[
\b[ compound command and the
2276 t
\bte
\bes
\bst
\bt and [
\b[ builtin commands to test file attributes and perform string
2277 and arithmetic comparisons. Expressions are formed from the following
2278 unary or binary primaries. If any _
\bf_
\bi_
\bl_
\be argument to one of the pri-
2279 maries is of the form _
\b/_
\bd_
\be_
\bv_
\b/_
\bf_
\bd_
\b/_
\bn, then file descriptor _
\bn is checked. If
2280 the _
\bf_
\bi_
\bl_
\be argument to one of the primaries is one of _
\b/_
\bd_
\be_
\bv_
\b/_
\bs_
\bt_
\bd_
\bi_
\bn,
2281 _
\b/_
\bd_
\be_
\bv_
\b/_
\bs_
\bt_
\bd_
\bo_
\bu_
\bt, or _
\b/_
\bd_
\be_
\bv_
\b/_
\bs_
\bt_
\bd_
\be_
\br_
\br, file descriptor 0, 1, or 2, respectively,
2284 Unless otherwise specified, primaries that operate on files follow sym-
2285 bolic links and operate on the target of the link, rather than the link
2288 When used with [
\b[[
\b[, the <
\b< and >
\b> operators sort lexicographically using
2289 the current locale. The t
\bte
\bes
\bst
\bt command sorts using ASCII ordering.
2291 -
\b-a
\ba _
\bf_
\bi_
\bl_
\be
2292 True if _
\bf_
\bi_
\bl_
\be exists.
2293 -
\b-b
\bb _
\bf_
\bi_
\bl_
\be
2294 True if _
\bf_
\bi_
\bl_
\be exists and is a block special file.
2295 -
\b-c
\bc _
\bf_
\bi_
\bl_
\be
2296 True if _
\bf_
\bi_
\bl_
\be exists and is a character special file.
2297 -
\b-d
\bd _
\bf_
\bi_
\bl_
\be
2298 True if _
\bf_
\bi_
\bl_
\be exists and is a directory.
2299 -
\b-e
\be _
\bf_
\bi_
\bl_
\be
2300 True if _
\bf_
\bi_
\bl_
\be exists.
2301 -
\b-f
\bf _
\bf_
\bi_
\bl_
\be
2302 True if _
\bf_
\bi_
\bl_
\be exists and is a regular file.
2303 -
\b-g
\bg _
\bf_
\bi_
\bl_
\be
2304 True if _
\bf_
\bi_
\bl_
\be exists and is set-group-id.
2305 -
\b-h
\bh _
\bf_
\bi_
\bl_
\be
2306 True if _
\bf_
\bi_
\bl_
\be exists and is a symbolic link.
2307 -
\b-k
\bk _
\bf_
\bi_
\bl_
\be
2308 True if _
\bf_
\bi_
\bl_
\be exists and its ``sticky'' bit is set.
2309 -
\b-p
\bp _
\bf_
\bi_
\bl_
\be
2310 True if _
\bf_
\bi_
\bl_
\be exists and is a named pipe (FIFO).
2311 -
\b-r
\br _
\bf_
\bi_
\bl_
\be
2312 True if _
\bf_
\bi_
\bl_
\be exists and is readable.
2313 -
\b-s
\bs _
\bf_
\bi_
\bl_
\be
2314 True if _
\bf_
\bi_
\bl_
\be exists and has a size greater than zero.
2315 -
\b-t
\bt _
\bf_
\bd True if file descriptor _
\bf_
\bd is open and refers to a terminal.
2316 -
\b-u
\bu _
\bf_
\bi_
\bl_
\be
2317 True if _
\bf_
\bi_
\bl_
\be exists and its set-user-id bit is set.
2318 -
\b-w
\bw _
\bf_
\bi_
\bl_
\be
2319 True if _
\bf_
\bi_
\bl_
\be exists and is writable.
2320 -
\b-x
\bx _
\bf_
\bi_
\bl_
\be
2321 True if _
\bf_
\bi_
\bl_
\be exists and is executable.
2322 -
\b-G
\bG _
\bf_
\bi_
\bl_
\be
2323 True if _
\bf_
\bi_
\bl_
\be exists and is owned by the effective group id.
2324 -
\b-L
\bL _
\bf_
\bi_
\bl_
\be
2325 True if _
\bf_
\bi_
\bl_
\be exists and is a symbolic link.
2326 -
\b-N
\bN _
\bf_
\bi_
\bl_
\be
2327 True if _
\bf_
\bi_
\bl_
\be exists and has been modified since it was last
2329 -
\b-O
\bO _
\bf_
\bi_
\bl_
\be
2330 True if _
\bf_
\bi_
\bl_
\be exists and is owned by the effective user id.
2331 -
\b-S
\bS _
\bf_
\bi_
\bl_
\be
2332 True if _
\bf_
\bi_
\bl_
\be exists and is a socket.
2333 _
\bf_
\bi_
\bl_
\be_
\b1 -
\b-e
\bef
\bf _
\bf_
\bi_
\bl_
\be_
\b2
2334 True if _
\bf_
\bi_
\bl_
\be_
\b1 and _
\bf_
\bi_
\bl_
\be_
\b2 refer to the same device and inode num-
2336 _
\bf_
\bi_
\bl_
\be_
\b1 -n
\bnt
\bt _
\bf_
\bi_
\bl_
\be_
\b2
2337 True if _
\bf_
\bi_
\bl_
\be_
\b1 is newer (according to modification date) than
2338 _
\bf_
\bi_
\bl_
\be_
\b2, or if _
\bf_
\bi_
\bl_
\be_
\b1 exists and _
\bf_
\bi_
\bl_
\be_
\b2 does not.
2339 _
\bf_
\bi_
\bl_
\be_
\b1 -o
\bot
\bt _
\bf_
\bi_
\bl_
\be_
\b2
2340 True if _
\bf_
\bi_
\bl_
\be_
\b1 is older than _
\bf_
\bi_
\bl_
\be_
\b2, or if _
\bf_
\bi_
\bl_
\be_
\b2 exists and _
\bf_
\bi_
\bl_
\be_
\b1
2342 -
\b-o
\bo _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be
2343 True if the shell option _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be is enabled. See the list of
2344 options under the description of the -
\b-o
\bo option to the s
\bse
\bet
\bt
2346 -
\b-v
\bv _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be
2347 True if the shell variable _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be is set (has been assigned a
2349 -
\b-R
\bR _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be
2350 True if the shell variable _
\bv_
\ba_
\br_
\bn_
\ba_
\bm_
\be is set and is a name refer-
2352 -
\b-z
\bz _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
2353 True if the length of _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is zero.
2354 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
2355 -
\b-n
\bn _
\bs_
\bt_
\br_
\bi_
\bn_
\bg
2356 True if the length of _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is non-zero.
2358 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 =
\b==
\b= _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
2359 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 =
\b= _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
2360 True if the strings are equal. =
\b= should be used with the t
\bte
\bes
\bst
\bt
2361 command for POSIX conformance. When used with the [
\b[[
\b[ command,
2362 this performs pattern matching as described above (C
\bCo
\bom
\bmp
\bpo
\bou
\bun
\bnd
\bd C
\bCo
\bom
\bm-
\b-
2363 m
\bma
\ban
\bnd
\bds
\bs).
2365 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 !
\b!=
\b= _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
2366 True if the strings are not equal.
2368 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 <
\b< _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
2369 True if _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 sorts before _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2 lexicographically.
2371 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 >
\b> _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2
2372 True if _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 sorts after _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2 lexicographically.
2374 _
\ba_
\br_
\bg_
\b1 O
\bOP
\bP _
\ba_
\br_
\bg_
\b2
2375 O
\bOP
\bP is one of -
\b-e
\beq
\bq, -
\b-n
\bne
\be, -
\b-l
\blt
\bt, -
\b-l
\ble
\be, -
\b-g
\bgt
\bt, or -
\b-g
\bge
\be. These arithmetic
2376 binary operators return true if _
\ba_
\br_
\bg_
\b1 is equal to, not equal to,
2377 less than, less than or equal to, greater than, or greater than
2378 or equal to _
\ba_
\br_
\bg_
\b2, respectively. _
\bA_
\br_
\bg_
\b1 and _
\ba_
\br_
\bg_
\b2 may be positive
2379 or negative integers.
2381 S
\bSI
\bIM
\bMP
\bPL
\bLE
\bE C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN
2382 When a simple command is executed, the shell performs the following
2383 expansions, assignments, and redirections, from left to right.
2385 1. The words that the parser has marked as variable assignments
2386 (those preceding the command name) and redirections are saved
2387 for later processing.
2389 2. The words that are not variable assignments or redirections are
2390 expanded. If any words remain after expansion, the first word
2391 is taken to be the name of the command and the remaining words
2394 3. Redirections are performed as described above under R
\bRE
\bED
\bDI
\bIR
\bRE
\bEC
\bCT
\bTI
\bIO
\bON
\bN.
2396 4. The text after the =
\b= in each variable assignment undergoes tilde
2397 expansion, parameter expansion, command substitution, arithmetic
2398 expansion, and quote removal before being assigned to the vari-
2401 If no command name results, the variable assignments affect the current
2402 shell environment. Otherwise, the variables are added to the environ-
2403 ment of the executed command and do not affect the current shell envi-
2404 ronment. If any of the assignments attempts to assign a value to a
2405 readonly variable, an error occurs, and the command exits with a non-
2408 If no command name results, redirections are performed, but do not
2409 affect the current shell environment. A redirection error causes the
2410 command to exit with a non-zero status.
2412 If there is a command name left after expansion, execution proceeds as
2413 described below. Otherwise, the command exits. If one of the expan-
2414 sions contained a command substitution, the exit status of the command
2415 is the exit status of the last command substitution performed. If
2416 there were no command substitutions, the command exits with a status of
2419 C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN
2420 After a command has been split into words, if it results in a simple
2421 command and an optional list of arguments, the following actions are
2424 If the command name contains no slashes, the shell attempts to locate
2425 it. If there exists a shell function by that name, that function is
2426 invoked as described above in F
\bFU
\bUN
\bNC
\bCT
\bTI
\bIO
\bON
\bNS
\bS. If the name does not match a
2427 function, the shell searches for it in the list of shell builtins. If
2428 a match is found, that builtin is invoked.
2430 If the name is neither a shell function nor a builtin, and contains no
2431 slashes, b
\bba
\bas
\bsh
\bh searches each element of the P
\bPA
\bAT
\bTH
\bH for a directory con-
2432 taining an executable file by that name. B
\bBa
\bas
\bsh
\bh uses a hash table to
2433 remember the full pathnames of executable files (see h
\bha
\bas
\bsh
\bh under S
\bSH
\bHE
\bEL
\bLL
\bL
2434 B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). A full search of the directories in P
\bPA
\bAT
\bTH
\bH is
2435 performed only if the command is not found in the hash table. If the
2436 search is unsuccessful, the shell searches for a defined shell function
2437 named c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd_
\b_n
\bno
\bot
\bt_
\b_f
\bfo
\bou
\bun
\bnd
\bd_
\b_h
\bha
\ban
\bnd
\bdl
\ble
\be. If that function exists, it is invoked
2438 with the original command and the original command's arguments as its
2439 arguments, and the function's exit status becomes the exit status of
2440 the shell. If that function is not defined, the shell prints an error
2441 message and returns an exit status of 127.
2443 If the search is successful, or if the command name contains one or
2444 more slashes, the shell executes the named program in a separate execu-
2445 tion environment. Argument 0 is set to the name given, and the remain-
2446 ing arguments to the command are set to the arguments given, if any.
2448 If this execution fails because the file is not in executable format,
2449 and the file is not a directory, it is assumed to be a _
\bs_
\bh_
\be_
\bl_
\bl _
\bs_
\bc_
\br_
\bi_
\bp_
\bt, a
2450 file containing shell commands. A subshell is spawned to execute it.
2451 This subshell reinitializes itself, so that the effect is as if a new
2452 shell had been invoked to handle the script, with the exception that
2453 the locations of commands remembered by the parent (see h
\bha
\bas
\bsh
\bh below
2454 under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS) are retained by the child.
2456 If the program is a file beginning with #
\b#!
\b!, the remainder of the first
2457 line specifies an interpreter for the program. The shell executes the
2458 specified interpreter on operating systems that do not handle this exe-
2459 cutable format themselves. The arguments to the interpreter consist of
2460 a single optional argument following the interpreter name on the first
2461 line of the program, followed by the name of the program, followed by
2462 the command arguments, if any.
2464 C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN E
\bEN
\bNV
\bVI
\bIR
\bRO
\bON
\bNM
\bME
\bEN
\bNT
\bT
2465 The shell has an _
\be_
\bx_
\be_
\bc_
\bu_
\bt_
\bi_
\bo_
\bn _
\be_
\bn_
\bv_
\bi_
\br_
\bo_
\bn_
\bm_
\be_
\bn_
\bt, which consists of the follow-
2468 +
\bo open files inherited by the shell at invocation, as modified by
2469 redirections supplied to the e
\bex
\bxe
\bec
\bc builtin
2471 +
\bo the current working directory as set by c
\bcd
\bd, p
\bpu
\bus
\bsh
\bhd
\bd, or p
\bpo
\bop
\bpd
\bd, or
2472 inherited by the shell at invocation
2474 +
\bo the file creation mode mask as set by u
\bum
\bma
\bas
\bsk
\bk or inherited from
2477 +
\bo current traps set by t
\btr
\bra
\bap
\bp
2479 +
\bo shell parameters that are set by variable assignment or with s
\bse
\bet
\bt
2480 or inherited from the shell's parent in the environment
2482 +
\bo shell functions defined during execution or inherited from the
2483 shell's parent in the environment
2485 +
\bo options enabled at invocation (either by default or with com-
2486 mand-line arguments) or by s
\bse
\bet
\bt
2488 +
\bo options enabled by s
\bsh
\bho
\bop
\bpt
\bt
2490 +
\bo shell aliases defined with a
\bal
\bli
\bia
\bas
\bs
2492 +
\bo various process IDs, including those of background jobs, the
2493 value of $
\b$$
\b$, and the value of P
\bPP
\bPI
\bID
\bD
2495 When a simple command other than a builtin or shell function is to be
2496 executed, it is invoked in a separate execution environment that con-
2497 sists of the following. Unless otherwise noted, the values are inher-
2498 ited from the shell.
2501 +
\bo the shell's open files, plus any modifications and additions
2502 specified by redirections to the command
2504 +
\bo the current working directory
2506 +
\bo the file creation mode mask
2508 +
\bo shell variables and functions marked for export, along with
2509 variables exported for the command, passed in the environment
2511 +
\bo traps caught by the shell are reset to the values inherited from
2512 the shell's parent, and traps ignored by the shell are ignored
2514 A command invoked in this separate environment cannot affect the
2515 shell's execution environment.
2517 Command substitution, commands grouped with parentheses, and asynchro-
2518 nous commands are invoked in a subshell environment that is a duplicate
2519 of the shell environment, except that traps caught by the shell are
2520 reset to the values that the shell inherited from its parent at invoca-
2521 tion. Builtin commands that are invoked as part of a pipeline are also
2522 executed in a subshell environment. Changes made to the subshell envi-
2523 ronment cannot affect the shell's execution environment.
2525 Subshells spawned to execute command substitutions inherit the value of
2526 the -
\b-e
\be option from the parent shell. When not in _
\bp_
\bo_
\bs_
\bi_
\bx mode, b
\bba
\bas
\bsh
\bh
2527 clears the -
\b-e
\be option in such subshells.
2529 If a command is followed by a &
\b& and job control is not active, the
2530 default standard input for the command is the empty file _
\b/_
\bd_
\be_
\bv_
\b/_
\bn_
\bu_
\bl_
\bl.
2531 Otherwise, the invoked command inherits the file descriptors of the
2532 calling shell as modified by redirections.
2534 E
\bEN
\bNV
\bVI
\bIR
\bRO
\bON
\bNM
\bME
\bEN
\bNT
\bT
2535 When a program is invoked it is given an array of strings called the
2536 _
\be_
\bn_
\bv_
\bi_
\br_
\bo_
\bn_
\bm_
\be_
\bn_
\bt. This is a list of _
\bn_
\ba_
\bm_
\be-_
\bv_
\ba_
\bl_
\bu_
\be pairs, of the form
2537 _
\bn_
\ba_
\bm_
\be=_
\bv_
\ba_
\bl_
\bu_
\be.
2539 The shell provides several ways to manipulate the environment. On
2540 invocation, the shell scans its own environment and creates a parameter
2541 for each name found, automatically marking it for _
\be_
\bx_
\bp_
\bo_
\br_
\bt to child pro-
2542 cesses. Executed commands inherit the environment. The e
\bex
\bxp
\bpo
\bor
\brt
\bt and
2543 d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-x
\bx commands allow parameters and functions to be added to and
2544 deleted from the environment. If the value of a parameter in the envi-
2545 ronment is modified, the new value becomes part of the environment,
2546 replacing the old. The environment inherited by any executed command
2547 consists of the shell's initial environment, whose values may be modi-
2548 fied in the shell, less any pairs removed by the u
\bun
\bns
\bse
\bet
\bt command, plus
2549 any additions via the e
\bex
\bxp
\bpo
\bor
\brt
\bt and d
\bde
\bec
\bcl
\bla
\bar
\bre
\be -
\b-x
\bx commands.
2551 The environment for any _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd or function may be augmented
2552 temporarily by prefixing it with parameter assignments, as described
2553 above in P
\bPA
\bAR
\bRA
\bAM
\bME
\bET
\bTE
\bER
\bRS
\bS. These assignment statements affect only the envi-
2554 ronment seen by that command.
2556 If the -
\b-k
\bk option is set (see the s
\bse
\bet
\bt builtin command below), then _
\ba_
\bl_
\bl
2557 parameter assignments are placed in the environment for a command, not
2558 just those that precede the command name.
2560 When b
\bba
\bas
\bsh
\bh invokes an external command, the variable _
\b_ is set to the
2561 full filename of the command and passed to that command in its environ-
2564 E
\bEX
\bXI
\bIT
\bT S
\bST
\bTA
\bAT
\bTU
\bUS
\bS
2565 The exit status of an executed command is the value returned by the
2566 _
\bw_
\ba_
\bi_
\bt_
\bp_
\bi_
\bd system call or equivalent function. Exit statuses fall between
2567 0 and 255, though, as explained below, the shell may use values above
2568 125 specially. Exit statuses from shell builtins and compound commands
2569 are also limited to this range. Under certain circumstances, the shell
2570 will use special values to indicate specific failure modes.
2572 For the shell's purposes, a command which exits with a zero exit status
2573 has succeeded. An exit status of zero indicates success. A non-zero
2574 exit status indicates failure. When a command terminates on a fatal
2575 signal _
\bN, b
\bba
\bas
\bsh
\bh uses the value of 128+_
\bN as the exit status.
2577 If a command is not found, the child process created to execute it
2578 returns a status of 127. If a command is found but is not executable,
2579 the return status is 126.
2581 If a command fails because of an error during expansion or redirection,
2582 the exit status is greater than zero.
2584 Shell builtin commands return a status of 0 (_
\bt_
\br_
\bu_
\be) if successful, and
2585 non-zero (_
\bf_
\ba_
\bl_
\bs_
\be) if an error occurs while they execute. All builtins
2586 return an exit status of 2 to indicate incorrect usage.
2588 B
\bBa
\bas
\bsh
\bh itself returns the exit status of the last command executed,
2589 unless a syntax error occurs, in which case it exits with a non-zero
2590 value. See also the e
\bex
\bxi
\bit
\bt builtin command below.
2592 S
\bSI
\bIG
\bGN
\bNA
\bAL
\bLS
\bS
2593 When b
\bba
\bas
\bsh
\bh is interactive, in the absence of any traps, it ignores
2594 S
\bSI
\bIG
\bGT
\bTE
\bER
\bRM
\bM (so that k
\bki
\bil
\bll
\bl 0
\b0 does not kill an interactive shell), and S
\bSI
\bIG
\bGI
\bIN
\bNT
\bT
2595 is caught and handled (so that the w
\bwa
\bai
\bit
\bt builtin is interruptible). In
2596 all cases, b
\bba
\bas
\bsh
\bh ignores S
\bSI
\bIG
\bGQ
\bQU
\bUI
\bIT
\bT. If job control is in effect, b
\bba
\bas
\bsh
\bh
2597 ignores S
\bSI
\bIG
\bGT
\bTT
\bTI
\bIN
\bN, S
\bSI
\bIG
\bGT
\bTT
\bTO
\bOU
\bU, and S
\bSI
\bIG
\bGT
\bTS
\bST
\bTP
\bP.
2599 Non-builtin commands run by b
\bba
\bas
\bsh
\bh have signal handlers set to the values
2600 inherited by the shell from its parent. When job control is not in
2601 effect, asynchronous commands ignore S
\bSI
\bIG
\bGI
\bIN
\bNT
\bT and S
\bSI
\bIG
\bGQ
\bQU
\bUI
\bIT
\bT in addition to
2602 these inherited handlers. Commands run as a result of command substi-
2603 tution ignore the keyboard-generated job control signals S
\bSI
\bIG
\bGT
\bTT
\bTI
\bIN
\bN, S
\bSI
\bIG
\bGT
\bT-
\b-
2604 T
\bTO
\bOU
\bU, and S
\bSI
\bIG
\bGT
\bTS
\bST
\bTP
\bP.
2606 The shell exits by default upon receipt of a S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP. Before exiting,
2607 an interactive shell resends the S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP to all jobs, running or
2608 stopped. Stopped jobs are sent S
\bSI
\bIG
\bGC
\bCO
\bON
\bNT
\bT to ensure that they receive the
2609 S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP. To prevent the shell from sending the signal to a particular
2610 job, it should be removed from the jobs table with the d
\bdi
\bis
\bso
\bow
\bwn
\bn builtin
2611 (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below) or marked to not receive S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP
2612 using d
\bdi
\bis
\bso
\bow
\bwn
\bn -
\b-h
\bh.
2614 If the h
\bhu
\bup
\bpo
\bon
\bne
\bex
\bxi
\bit
\bt shell option has been set with s
\bsh
\bho
\bop
\bpt
\bt, b
\bba
\bas
\bsh
\bh sends a
2615 S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP to all jobs when an interactive login shell exits.
2617 If b
\bba
\bas
\bsh
\bh is waiting for a command to complete and receives a signal for
2618 which a trap has been set, the trap will not be executed until the com-
2619 mand completes. When b
\bba
\bas
\bsh
\bh is waiting for an asynchronous command via
2620 the w
\bwa
\bai
\bit
\bt builtin, the reception of a signal for which a trap has been
2621 set will cause the w
\bwa
\bai
\bit
\bt builtin to return immediately with an exit sta-
2622 tus greater than 128, immediately after which the trap is executed.
2624 J
\bJO
\bOB
\bB C
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL
2625 _
\bJ_
\bo_
\bb _
\bc_
\bo_
\bn_
\bt_
\br_
\bo_
\bl refers to the ability to selectively stop (_
\bs_
\bu_
\bs_
\bp_
\be_
\bn_
\bd) the
2626 execution of processes and continue (_
\br_
\be_
\bs_
\bu_
\bm_
\be) their execution at a later
2627 point. A user typically employs this facility via an interactive
2628 interface supplied jointly by the operating system kernel's terminal
2629 driver and b
\bba
\bas
\bsh
\bh.
2631 The shell associates a _
\bj_
\bo_
\bb with each pipeline. It keeps a table of
2632 currently executing jobs, which may be listed with the j
\bjo
\bob
\bbs
\bs command.
2633 When b
\bba
\bas
\bsh
\bh starts a job asynchronously (in the _
\bb_
\ba_
\bc_
\bk_
\bg_
\br_
\bo_
\bu_
\bn_
\bd), it prints a
2634 line that looks like:
2638 indicating that this job is job number 1 and that the process ID of the
2639 last process in the pipeline associated with this job is 25647. All of
2640 the processes in a single pipeline are members of the same job. B
\bBa
\bas
\bsh
\bh
2641 uses the _
\bj_
\bo_
\bb abstraction as the basis for job control.
2643 To facilitate the implementation of the user interface to job control,
2644 the operating system maintains the notion of a _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bt_
\be_
\br_
\bm_
\bi_
\bn_
\ba_
\bl _
\bp_
\br_
\bo_
\bc_
\be_
\bs_
\bs
2645 _
\bg_
\br_
\bo_
\bu_
\bp _
\bI_
\bD. Members of this process group (processes whose process group
2646 ID is equal to the current terminal process group ID) receive keyboard-
2647 generated signals such as S
\bSI
\bIG
\bGI
\bIN
\bNT
\bT. These processes are said to be in
2648 the _
\bf_
\bo_
\br_
\be_
\bg_
\br_
\bo_
\bu_
\bn_
\bd. _
\bB_
\ba_
\bc_
\bk_
\bg_
\br_
\bo_
\bu_
\bn_
\bd processes are those whose process group ID
2649 differs from the terminal's; such processes are immune to keyboard-gen-
2650 erated signals. Only foreground processes are allowed to read from or,
2651 if the user so specifies with stty tostop, write to the terminal.
2652 Background processes which attempt to read from (write to when stty
2653 tostop is in effect) the terminal are sent a S
\bSI
\bIG
\bGT
\bTT
\bTI
\bIN
\bN (
\b(S
\bSI
\bIG
\bGT
\bTT
\bTO
\bOU
\bU)
\b) signal
2654 by the kernel's terminal driver, which, unless caught, suspends the
2657 If the operating system on which b
\bba
\bas
\bsh
\bh is running supports job control,
2658 b
\bba
\bas
\bsh
\bh contains facilities to use it. Typing the _
\bs_
\bu_
\bs_
\bp_
\be_
\bn_
\bd character (typ-
2659 ically ^
\b^Z
\bZ, Control-Z) while a process is running causes that process to
2660 be stopped and returns control to b
\bba
\bas
\bsh
\bh. Typing the _
\bd_
\be_
\bl_
\ba_
\by_
\be_
\bd _
\bs_
\bu_
\bs_
\bp_
\be_
\bn_
\bd
2661 character (typically ^
\b^Y
\bY, Control-Y) causes the process to be stopped
2662 when it attempts to read input from the terminal, and control to be
2663 returned to b
\bba
\bas
\bsh
\bh. The user may then manipulate the state of this job,
2664 using the b
\bbg
\bg command to continue it in the background, the f
\bfg
\bg command
2665 to continue it in the foreground, or the k
\bki
\bil
\bll
\bl command to kill it. A ^
\b^Z
\bZ
2666 takes effect immediately, and has the additional side effect of causing
2667 pending output and typeahead to be discarded.
2669 There are a number of ways to refer to a job in the shell. The charac-
2670 ter %
\b% introduces a job specification (_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc). Job number _
\bn may be
2671 referred to as %
\b%n
\bn. A job may also be referred to using a prefix of the
2672 name used to start it, or using a substring that appears in its command
2673 line. For example, %
\b%c
\bce
\be refers to a stopped c
\bce
\be job. If a prefix
2674 matches more than one job, b
\bba
\bas
\bsh
\bh reports an error. Using %
\b%?
\b?c
\bce
\be, on the
2675 other hand, refers to any job containing the string c
\bce
\be in its command
2676 line. If the substring matches more than one job, b
\bba
\bas
\bsh
\bh reports an
2677 error. The symbols %
\b%%
\b% and %
\b%+
\b+ refer to the shell's notion of the _
\bc_
\bu_
\br_
\b-
2678 _
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb, which is the last job stopped while it was in the foreground
2679 or started in the background. The _
\bp_
\br_
\be_
\bv_
\bi_
\bo_
\bu_
\bs _
\bj_
\bo_
\bb may be referenced using
2680 %
\b%-
\b-. If there is only a single job, %
\b%+
\b+ and %
\b%-
\b- can both be used to refer
2681 to that job. In output pertaining to jobs (e.g., the output of the
2682 j
\bjo
\bob
\bbs
\bs command), the current job is always flagged with a +
\b+, and the pre-
2683 vious job with a -
\b-. A single % (with no accompanying job specifica-
2684 tion) also refers to the current job.
2686 Simply naming a job can be used to bring it into the foreground: %
\b%1
\b1 is
2687 a synonym for `
\b``
\b`f
\bfg
\bg %
\b%1
\b1'
\b''
\b', bringing job 1 from the background into the
2688 foreground. Similarly, `
\b``
\b`%
\b%1
\b1 &
\b&'
\b''
\b' resumes job 1 in the background,
2689 equivalent to `
\b``
\b`b
\bbg
\bg %
\b%1
\b1'
\b''
\b'.
2691 The shell learns immediately whenever a job changes state. Normally,
2692 b
\bba
\bas
\bsh
\bh waits until it is about to print a prompt before reporting changes
2693 in a job's status so as to not interrupt any other output. If the -
\b-b
\bb
2694 option to the s
\bse
\bet
\bt builtin command is enabled, b
\bba
\bas
\bsh
\bh reports such changes
2695 immediately. Any trap on S
\bSI
\bIG
\bGC
\bCH
\bHL
\bLD
\bD is executed for each child that
2698 If an attempt to exit b
\bba
\bas
\bsh
\bh is made while jobs are stopped (or, if the
2699 c
\bch
\bhe
\bec
\bck
\bkj
\bjo
\bob
\bbs
\bs shell option has been enabled using the s
\bsh
\bho
\bop
\bpt
\bt builtin, run-
2700 ning), the shell prints a warning message, and, if the c
\bch
\bhe
\bec
\bck
\bkj
\bjo
\bob
\bbs
\bs option
2701 is enabled, lists the jobs and their statuses. The j
\bjo
\bob
\bbs
\bs command may
2702 then be used to inspect their status. If a second attempt to exit is
2703 made without an intervening command, the shell does not print another
2704 warning, and any stopped jobs are terminated.
2706 P
\bPR
\bRO
\bOM
\bMP
\bPT
\bTI
\bIN
\bNG
\bG
2707 When executing interactively, b
\bba
\bas
\bsh
\bh displays the primary prompt P
\bPS
\bS1
\b1 when
2708 it is ready to read a command, and the secondary prompt P
\bPS
\bS2
\b2 when it
2709 needs more input to complete a command. B
\bBa
\bas
\bsh
\bh allows these prompt
2710 strings to be customized by inserting a number of backslash-escaped
2711 special characters that are decoded as follows:
2712 \
\b\a
\ba an ASCII bell character (07)
2713 \
\b\d
\bd the date in "Weekday Month Date" format (e.g., "Tue May
2715 \
\b\D
\bD{
\b{_
\bf_
\bo_
\br_
\bm_
\ba_
\bt}
\b}
2716 the _
\bf_
\bo_
\br_
\bm_
\ba_
\bt is passed to _
\bs_
\bt_
\br_
\bf_
\bt_
\bi_
\bm_
\be(3) and the result is
2717 inserted into the prompt string; an empty _
\bf_
\bo_
\br_
\bm_
\ba_
\bt results
2718 in a locale-specific time representation. The braces are
2720 \
\b\e
\be an ASCII escape character (033)
2721 \
\b\h
\bh the hostname up to the first `.'
2722 \
\b\H
\bH the hostname
2723 \
\b\j
\bj the number of jobs currently managed by the shell
2724 \
\b\l
\bl the basename of the shell's terminal device name
2726 \
\b\r
\br carriage return
2727 \
\b\s
\bs the name of the shell, the basename of $
\b$0
\b0 (the portion
2728 following the final slash)
2729 \
\b\t
\bt the current time in 24-hour HH:MM:SS format
2730 \
\b\T
\bT the current time in 12-hour HH:MM:SS format
2731 \
\b\@
\b@ the current time in 12-hour am/pm format
2732 \
\b\A
\bA the current time in 24-hour HH:MM format
2733 \
\b\u
\bu the username of the current user
2734 \
\b\v
\bv the version of b
\bba
\bas
\bsh
\bh (e.g., 2.00)
2735 \
\b\V
\bV the release of b
\bba
\bas
\bsh
\bh, version + patch level (e.g., 2.00.0)
2736 \
\b\w
\bw the current working directory, with $
\b$H
\bHO
\bOM
\bME
\bE abbreviated
2737 with a tilde (uses the value of the P
\bPR
\bRO
\bOM
\bMP
\bPT
\bT_
\b_D
\bDI
\bIR
\bRT
\bTR
\bRI
\bIM
\bM vari-
2739 \
\b\W
\bW the basename of the current working directory, with $
\b$H
\bHO
\bOM
\bME
\bE
2740 abbreviated with a tilde
2741 \
\b\!
\b! the history number of this command
2742 \
\b\#
\b# the command number of this command
2743 \
\b\$
\b$ if the effective UID is 0, a #
\b#, otherwise a $
\b$
2744 \
\b\_
\bn_
\bn_
\bn the character corresponding to the octal number _
\bn_
\bn_
\bn
2745 \
\b\\
\b\ a backslash
2746 \
\b\[
\b[ begin a sequence of non-printing characters, which could
2747 be used to embed a terminal control sequence into the
2749 \
\b\]
\b] end a sequence of non-printing characters
2751 The command number and the history number are usually different: the
2752 history number of a command is its position in the history list, which
2753 may include commands restored from the history file (see H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY
2754 below), while the command number is the position in the sequence of
2755 commands executed during the current shell session. After the string
2756 is decoded, it is expanded via parameter expansion, command substitu-
2757 tion, arithmetic expansion, and quote removal, subject to the value of
2758 the p
\bpr
\bro
\bom
\bmp
\bpt
\btv
\bva
\bar
\brs
\bs shell option (see the description of the s
\bsh
\bho
\bop
\bpt
\bt command
2759 under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
2761 R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE
2762 This is the library that handles reading input when using an interac-
2763 tive shell, unless the -
\b--
\b-n
\bno
\boe
\bed
\bdi
\bit
\bti
\bin
\bng
\bg option is given at shell invocation.
2764 Line editing is also used when using the -
\b-e
\be option to the r
\bre
\bea
\bad
\bd builtin.
2765 By default, the line editing commands are similar to those of Emacs. A
2766 vi-style line editing interface is also available. Line editing can be
2767 enabled at any time using the -
\b-o
\bo e
\bem
\bma
\bac
\bcs
\bs or -
\b-o
\bo v
\bvi
\bi options to the s
\bse
\bet
\bt
2768 builtin (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). To turn off line editing
2769 after the shell is running, use the +
\b+o
\bo e
\bem
\bma
\bac
\bcs
\bs or +
\b+o
\bo v
\bvi
\bi options to the
2770 s
\bse
\bet
\bt builtin.
2772 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be N
\bNo
\bot
\bta
\bat
\bti
\bio
\bon
\bn
2773 In this section, the Emacs-style notation is used to denote keystrokes.
2774 Control keys are denoted by C-_
\bk_
\be_
\by, e.g., C-n means Control-N. Simi-
2775 larly, _
\bm_
\be_
\bt_
\ba keys are denoted by M-_
\bk_
\be_
\by, so M-x means Meta-X. (On key-
2776 boards without a _
\bm_
\be_
\bt_
\ba key, M-_
\bx means ESC _
\bx, i.e., press the Escape key
2777 then the _
\bx key. This makes ESC the _
\bm_
\be_
\bt_
\ba _
\bp_
\br_
\be_
\bf_
\bi_
\bx. The combination M-C-_
\bx
2778 means ESC-Control-_
\bx, or press the Escape key then hold the Control key
2779 while pressing the _
\bx key.)
2781 Readline commands may be given numeric _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs, which normally act as
2782 a repeat count. Sometimes, however, it is the sign of the argument
2783 that is significant. Passing a negative argument to a command that
2784 acts in the forward direction (e.g., k
\bki
\bil
\bll
\bl-
\b-l
\bli
\bin
\bne
\be) causes that command to
2785 act in a backward direction. Commands whose behavior with arguments
2786 deviates from this are noted below.
2788 When a command is described as _
\bk_
\bi_
\bl_
\bl_
\bi_
\bn_
\bg text, the text deleted is saved
2789 for possible future retrieval (_
\by_
\ba_
\bn_
\bk_
\bi_
\bn_
\bg). The killed text is saved in a
2790 _
\bk_
\bi_
\bl_
\bl _
\br_
\bi_
\bn_
\bg. Consecutive kills cause the text to be accumulated into one
2791 unit, which can be yanked all at once. Commands which do not kill text
2792 separate the chunks of text on the kill ring.
2794 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be I
\bIn
\bni
\bit
\bti
\bia
\bal
\bli
\biz
\bza
\bat
\bti
\bio
\bon
\bn
2795 Readline is customized by putting commands in an initialization file
2796 (the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file). The name of this file is taken from the value of
2797 the I
\bIN
\bNP
\bPU
\bUT
\bTR
\bRC
\bC variable. If that variable is unset, the default is
2798 _
\b~_
\b/_
\b._
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc. When a program which uses the readline library starts up,
2799 the initialization file is read, and the key bindings and variables are
2800 set. There are only a few basic constructs allowed in the readline
2801 initialization file. Blank lines are ignored. Lines beginning with a
2802 #
\b# are comments. Lines beginning with a $
\b$ indicate conditional con-
2803 structs. Other lines denote key bindings and variable settings.
2805 The default key-bindings may be changed with an _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file. Other
2806 programs that use this library may add their own commands and bindings.
2808 For example, placing
2810 M-Control-u: universal-argument
2812 C-Meta-u: universal-argument
2813 into the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc would make M-C-u execute the readline command _
\bu_
\bn_
\bi_
\bv_
\be_
\br_
\b-
2814 _
\bs_
\ba_
\bl_
\b-_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt.
2816 The following symbolic character names are recognized: _
\bR_
\bU_
\bB_
\bO_
\bU_
\bT, _
\bD_
\bE_
\bL,
2817 _
\bE_
\bS_
\bC, _
\bL_
\bF_
\bD, _
\bN_
\bE_
\bW_
\bL_
\bI_
\bN_
\bE, _
\bR_
\bE_
\bT, _
\bR_
\bE_
\bT_
\bU_
\bR_
\bN, _
\bS_
\bP_
\bC, _
\bS_
\bP_
\bA_
\bC_
\bE, and _
\bT_
\bA_
\bB.
2819 In addition to command names, readline allows keys to be bound to a
2820 string that is inserted when the key is pressed (a _
\bm_
\ba_
\bc_
\br_
\bo).
2822 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be K
\bKe
\bey
\by B
\bBi
\bin
\bnd
\bdi
\bin
\bng
\bgs
\bs
2823 The syntax for controlling key bindings in the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file is simple.
2824 All that is required is the name of the command or the text of a macro
2825 and a key sequence to which it should be bound. The name may be speci-
2826 fied in one of two ways: as a symbolic key name, possibly with _
\bM_
\be_
\bt_
\ba_
\b- or
2827 _
\bC_
\bo_
\bn_
\bt_
\br_
\bo_
\bl_
\b- prefixes, or as a key sequence.
2829 When using the form k
\bke
\bey
\byn
\bna
\bam
\bme
\be:_
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be or _
\bm_
\ba_
\bc_
\br_
\bo, _
\bk_
\be_
\by_
\bn_
\ba_
\bm_
\be is the name
2830 of a key spelled out in English. For example:
2832 Control-u: universal-argument
2833 Meta-Rubout: backward-kill-word
2834 Control-o: "> output"
2836 In the above example, _
\bC_
\b-_
\bu is bound to the function u
\bun
\bni
\biv
\bve
\ber
\brs
\bsa
\bal
\bl-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt,
2837 _
\bM_
\b-_
\bD_
\bE_
\bL is bound to the function b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-k
\bki
\bil
\bll
\bl-
\b-w
\bwo
\bor
\brd
\bd, and _
\bC_
\b-_
\bo is bound to
2838 run the macro expressed on the right hand side (that is, to insert the
2839 text ``> output'' into the line).
2841 In the second form, "
\b"k
\bke
\bey
\bys
\bse
\beq
\bq"
\b":_
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be or _
\bm_
\ba_
\bc_
\br_
\bo, k
\bke
\bey
\bys
\bse
\beq
\bq differs
2842 from k
\bke
\bey
\byn
\bna
\bam
\bme
\be above in that strings denoting an entire key sequence may
2843 be specified by placing the sequence within double quotes. Some GNU
2844 Emacs style key escapes can be used, as in the following example, but
2845 the symbolic character names are not recognized.
2847 "\C-u": universal-argument
2848 "\C-x\C-r": re-read-init-file
2849 "\e[11~": "Function Key 1"
2851 In this example, _
\bC_
\b-_
\bu is again bound to the function u
\bun
\bni
\biv
\bve
\ber
\brs
\bsa
\bal
\bl-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt.
2852 _
\bC_
\b-_
\bx _
\bC_
\b-_
\br is bound to the function r
\bre
\be-
\b-r
\bre
\bea
\bad
\bd-
\b-i
\bin
\bni
\bit
\bt-
\b-f
\bfi
\bil
\ble
\be, and _
\bE_
\bS_
\bC _
\b[ _
\b1 _
\b1 _
\b~ is
2853 bound to insert the text ``Function Key 1''.
2855 The full set of GNU Emacs style escape sequences is
2856 \
\b\C
\bC-
\b- control prefix
2857 \
\b\M
\bM-
\b- meta prefix
2858 \
\b\e
\be an escape character
2863 In addition to the GNU Emacs style escape sequences, a second set of
2864 backslash escapes is available:
2865 \
\b\a
\ba alert (bell)
2870 \
\b\r
\br carriage return
2871 \
\b\t
\bt horizontal tab
2872 \
\b\v
\bv vertical tab
2873 \
\b\_
\bn_
\bn_
\bn the eight-bit character whose value is the octal value
2874 _
\bn_
\bn_
\bn (one to three digits)
2875 \
\b\x
\bx_
\bH_
\bH the eight-bit character whose value is the hexadecimal
2876 value _
\bH_
\bH (one or two hex digits)
2878 When entering the text of a macro, single or double quotes must be used
2879 to indicate a macro definition. Unquoted text is assumed to be a func-
2880 tion name. In the macro body, the backslash escapes described above
2881 are expanded. Backslash will quote any other character in the macro
2882 text, including " and '.
2884 B
\bBa
\bas
\bsh
\bh allows the current readline key bindings to be displayed or modi-
2885 fied with the b
\bbi
\bin
\bnd
\bd builtin command. The editing mode may be switched
2886 during interactive use by using the -
\b-o
\bo option to the s
\bse
\bet
\bt builtin com-
2887 mand (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below).
2889 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs
2890 Readline has variables that can be used to further customize its behav-
2891 ior. A variable may be set in the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file with a statement of the
2894 s
\bse
\bet
\bt _
\bv_
\ba_
\br_
\bi_
\ba_
\bb_
\bl_
\be_
\b-_
\bn_
\ba_
\bm_
\be _
\bv_
\ba_
\bl_
\bu_
\be
2896 Except where noted, readline variables can take the values O
\bOn
\bn or O
\bOf
\bff
\bf
2897 (without regard to case). Unrecognized variable names are ignored.
2898 When a variable value is read, empty or null values, "on" (case-insen-
2899 sitive), and "1" are equivalent to O
\bOn
\bn. All other values are equivalent
2900 to O
\bOf
\bff
\bf. The variables and their default values are:
2902 b
\bbe
\bel
\bll
\bl-
\b-s
\bst
\bty
\byl
\ble
\be (
\b(a
\bau
\bud
\bdi
\bib
\bbl
\ble
\be)
\b)
2903 Controls what happens when readline wants to ring the terminal
2904 bell. If set to n
\bno
\bon
\bne
\be, readline never rings the bell. If set to
2905 v
\bvi
\bis
\bsi
\bib
\bbl
\ble
\be, readline uses a visible bell if one is available. If
2906 set to a
\bau
\bud
\bdi
\bib
\bbl
\ble
\be, readline attempts to ring the terminal's bell.
2907 b
\bbi
\bin
\bnd
\bd-
\b-t
\btt
\bty
\by-
\b-s
\bsp
\bpe
\bec
\bci
\bia
\bal
\bl-
\b-c
\bch
\bha
\bar
\brs
\bs (
\b(O
\bOn
\bn)
\b)
2908 If set to O
\bOn
\bn, readline attempts to bind the control characters
2909 treated specially by the kernel's terminal driver to their read-
2911 c
\bco
\bol
\blo
\bor
\bre
\bed
\bd-
\b-s
\bst
\bta
\bat
\bts
\bs (
\b(O
\bOf
\bff
\bf)
\b)
2912 If set to O
\bOn
\bn, readline displays possible completions using dif-
2913 ferent colors to indicate their file type. The color defini-
2914 tions are taken from the value of the L
\bLS
\bS_
\b_C
\bCO
\bOL
\bLO
\bOR
\bRS
\bS environment
2916 c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt-
\b-b
\bbe
\beg
\bgi
\bin
\bn (
\b(`
\b``
\b`#
\b#'
\b''
\b')
\b)
2917 The string that is inserted when the readline i
\bin
\bns
\bse
\ber
\brt
\bt-
\b-c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt
2918 command is executed. This command is bound to M
\bM-
\b-#
\b# in emacs mode
2919 and to #
\b# in vi command mode.
2920 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn-
\b-i
\big
\bgn
\bno
\bor
\bre
\be-
\b-c
\bca
\bas
\bse
\be (
\b(O
\bOf
\bff
\bf)
\b)
2921 If set to O
\bOn
\bn, readline performs filename matching and completion
2922 in a case-insensitive fashion.
2923 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn-
\b-p
\bpr
\bre
\bef
\bfi
\bix
\bx-
\b-d
\bdi
\bis
\bsp
\bpl
\bla
\bay
\by-
\b-l
\ble
\ben
\bng
\bgt
\bth
\bh (
\b(0
\b0)
\b)
2924 The length in characters of the common prefix of a list of pos-
2925 sible completions that is displayed without modification. When
2926 set to a value greater than zero, common prefixes longer than
2927 this value are replaced with an ellipsis when displaying possi-
2929 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn-
\b-q
\bqu
\bue
\ber
\bry
\by-
\b-i
\bit
\bte
\bem
\bms
\bs (
\b(1
\b10
\b00
\b0)
\b)
2930 This determines when the user is queried about viewing the num-
2931 ber of possible completions generated by the p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\be-
\b-
2932 t
\bti
\bio
\bon
\bns
\bs command. It may be set to any integer value greater than
2933 or equal to zero. If the number of possible completions is
2934 greater than or equal to the value of this variable, the user is
2935 asked whether or not he wishes to view them; otherwise they are
2936 simply listed on the terminal.
2937 c
\bco
\bon
\bnv
\bve
\ber
\brt
\bt-
\b-m
\bme
\bet
\bta
\ba (
\b(O
\bOn
\bn)
\b)
2938 If set to O
\bOn
\bn, readline will convert characters with the eighth
2939 bit set to an ASCII key sequence by stripping the eighth bit and
2940 prefixing an escape character (in effect, using escape as the
2941 _
\bm_
\be_
\bt_
\ba _
\bp_
\br_
\be_
\bf_
\bi_
\bx).
2942 d
\bdi
\bis
\bsa
\bab
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn (
\b(O
\bOf
\bff
\bf)
\b)
2943 If set to O
\bOn
\bn, readline will inhibit word completion. Completion
2944 characters will be inserted into the line as if they had been
2945 mapped to s
\bse
\bel
\blf
\bf-
\b-i
\bin
\bns
\bse
\ber
\brt
\bt.
2946 e
\bed
\bdi
\bit
\bti
\bin
\bng
\bg-
\b-m
\bmo
\bod
\bde
\be (
\b(e
\bem
\bma
\bac
\bcs
\bs)
\b)
2947 Controls whether readline begins with a set of key bindings sim-
2948 ilar to _
\bE_
\bm_
\ba_
\bc_
\bs or _
\bv_
\bi. e
\bed
\bdi
\bit
\bti
\bin
\bng
\bg-
\b-m
\bmo
\bod
\bde
\be can be set to either e
\bem
\bma
\bac
\bcs
\bs or
2950 e
\bec
\bch
\bho
\bo-
\b-c
\bco
\bon
\bnt
\btr
\bro
\bol
\bl-
\b-c
\bch
\bha
\bar
\bra
\bac
\bct
\bte
\ber
\brs
\bs (
\b(O
\bOn
\bn)
\b)
2951 When set to O
\bOn
\bn, on operating systems that indicate they support
2952 it, readline echoes a character corresponding to a signal gener-
2953 ated from the keyboard.
2954 e
\ben
\bna
\bab
\bbl
\ble
\be-
\b-k
\bke
\bey
\byp
\bpa
\bad
\bd (
\b(O
\bOf
\bff
\bf)
\b)
2955 When set to O
\bOn
\bn, readline will try to enable the application key-
2956 pad when it is called. Some systems need this to enable the
2958 e
\ben
\bna
\bab
\bbl
\ble
\be-
\b-m
\bme
\bet
\bta
\ba-
\b-k
\bke
\bey
\by (
\b(O
\bOn
\bn)
\b)
2959 When set to O
\bOn
\bn, readline will try to enable any meta modifier
2960 key the terminal claims to support when it is called. On many
2961 terminals, the meta key is used to send eight-bit characters.
2962 e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-t
\bti
\bil
\bld
\bde
\be (
\b(O
\bOf
\bff
\bf)
\b)
2963 If set to O
\bOn
\bn, tilde expansion is performed when readline
2964 attempts word completion.
2965 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-p
\bpr
\bre
\bes
\bse
\ber
\brv
\bve
\be-
\b-p
\bpo
\boi
\bin
\bnt
\bt (
\b(O
\bOf
\bff
\bf)
\b)
2966 If set to O
\bOn
\bn, the history code attempts to place point at the
2967 same location on each history line retrieved with p
\bpr
\bre
\bev
\bvi
\bio
\bou
\bus
\bs-
\b-h
\bhi
\bis
\bs-
\b-
2968 t
\bto
\bor
\bry
\by or n
\bne
\bex
\bxt
\bt-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by.
2969 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-s
\bsi
\biz
\bze
\be (
\b(0
\b0)
\b)
2970 Set the maximum number of history entries saved in the history
2971 list. If set to zero, any existing history entries are deleted
2972 and no new entries are saved. If set to a value less than zero,
2973 the number of history entries is not limited. By default, the
2974 number of history entries is not limited.
2975 h
\bho
\bor
\bri
\biz
\bzo
\bon
\bnt
\bta
\bal
\bl-
\b-s
\bsc
\bcr
\bro
\bol
\bll
\bl-
\b-m
\bmo
\bod
\bde
\be (
\b(O
\bOf
\bff
\bf)
\b)
2976 When set to O
\bOn
\bn, makes readline use a single line for display,
2977 scrolling the input horizontally on a single screen line when it
2978 becomes longer than the screen width rather than wrapping to a
2980 i
\bin
\bnp
\bpu
\but
\bt-
\b-m
\bme
\bet
\bta
\ba (
\b(O
\bOf
\bff
\bf)
\b)
2981 If set to O
\bOn
\bn, readline will enable eight-bit input (that is, it
2982 will not strip the high bit from the characters it reads),
2983 regardless of what the terminal claims it can support. The name
2984 m
\bme
\bet
\bta
\ba-
\b-f
\bfl
\bla
\bag
\bg is a synonym for this variable.
2985 i
\bis
\bse
\bea
\bar
\brc
\bch
\bh-
\b-t
\bte
\ber
\brm
\bmi
\bin
\bna
\bat
\bto
\bor
\brs
\bs (
\b(`
\b``
\b`C
\bC-
\b-[
\b[C
\bC-
\b-J
\bJ'
\b''
\b')
\b)
2986 The string of characters that should terminate an incremental
2987 search without subsequently executing the character as a com-
2988 mand. If this variable has not been given a value, the charac-
2989 ters _
\bE_
\bS_
\bC and _
\bC_
\b-_
\bJ will terminate an incremental search.
2990 k
\bke
\bey
\bym
\bma
\bap
\bp (
\b(e
\bem
\bma
\bac
\bcs
\bs)
\b)
2991 Set the current readline keymap. The set of valid keymap names
2992 is _
\be_
\bm_
\ba_
\bc_
\bs_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bm_
\be_
\bt_
\ba_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bc_
\bt_
\bl_
\bx_
\b, _
\bv_
\bi_
\b, _
\bv_
\bi_
\b-_
\bc_
\bo_
\bm_
\b-
2993 _
\bm_
\ba_
\bn_
\bd, and _
\bv_
\bi_
\b-_
\bi_
\bn_
\bs_
\be_
\br_
\bt. _
\bv_
\bi is equivalent to _
\bv_
\bi_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd; _
\be_
\bm_
\ba_
\bc_
\bs is
2994 equivalent to _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd. The default value is _
\be_
\bm_
\ba_
\bc_
\bs; the
2995 value of e
\bed
\bdi
\bit
\bti
\bin
\bng
\bg-
\b-m
\bmo
\bod
\bde
\be also affects the default keymap.
2996 k
\bke
\bey
\bys
\bse
\beq
\bq-
\b-t
\bti
\bim
\bme
\beo
\bou
\but
\bt (
\b(5
\b50
\b00
\b0)
\b)
2997 Specifies the duration _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be will wait for a character when
2998 reading an ambiguous key sequence (one that can form a complete
2999 key sequence using the input read so far, or can take additional
3000 input to complete a longer key sequence). If no input is
3001 received within the timeout, _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be will use the shorter but
3002 complete key sequence. The value is specified in milliseconds,
3003 so a value of 1000 means that _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be will wait one second for
3004 additional input. If this variable is set to a value less than
3005 or equal to zero, or to a non-numeric value, _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be will wait
3006 until another key is pressed to decide which key sequence to
3008 m
\bma
\bar
\brk
\bk-
\b-d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bri
\bie
\bes
\bs (
\b(O
\bOn
\bn)
\b)
3009 If set to O
\bOn
\bn, completed directory names have a slash appended.
3010 m
\bma
\bar
\brk
\bk-
\b-m
\bmo
\bod
\bdi
\bif
\bfi
\bie
\bed
\bd-
\b-l
\bli
\bin
\bne
\bes
\bs (
\b(O
\bOf
\bff
\bf)
\b)
3011 If set to O
\bOn
\bn, history lines that have been modified are dis-
3012 played with a preceding asterisk (*
\b*).
3013 m
\bma
\bar
\brk
\bk-
\b-s
\bsy
\bym
\bml
\bli
\bin
\bnk
\bke
\bed
\bd-
\b-d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bri
\bie
\bes
\bs (
\b(O
\bOf
\bff
\bf)
\b)
3014 If set to O
\bOn
\bn, completed names which are symbolic links to direc-
3015 tories have a slash appended (subject to the value of
3016 m
\bma
\bar
\brk
\bk-
\b-d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bri
\bie
\bes
\bs).
3017 m
\bma
\bat
\btc
\bch
\bh-
\b-h
\bhi
\bid
\bdd
\bde
\ben
\bn-
\b-f
\bfi
\bil
\ble
\bes
\bs (
\b(O
\bOn
\bn)
\b)
3018 This variable, when set to O
\bOn
\bn, causes readline to match files
3019 whose names begin with a `.' (hidden files) when performing
3020 filename completion. If set to O
\bOf
\bff
\bf, the leading `.' must be
3021 supplied by the user in the filename to be completed.
3022 m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-d
\bdi
\bis
\bsp
\bpl
\bla
\bay
\by-
\b-p
\bpr
\bre
\bef
\bfi
\bix
\bx (
\b(O
\bOf
\bff
\bf)
\b)
3023 If set to O
\bOn
\bn, menu completion displays the common prefix of the
3024 list of possible completions (which may be empty) before cycling
3026 o
\bou
\but
\btp
\bpu
\but
\bt-
\b-m
\bme
\bet
\bta
\ba (
\b(O
\bOf
\bff
\bf)
\b)
3027 If set to O
\bOn
\bn, readline will display characters with the eighth
3028 bit set directly rather than as a meta-prefixed escape sequence.
3029 p
\bpa
\bag
\bge
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(O
\bOn
\bn)
\b)
3030 If set to O
\bOn
\bn, readline uses an internal _
\bm_
\bo_
\br_
\be-like pager to dis-
3031 play a screenful of possible completions at a time.
3032 p
\bpr
\bri
\bin
\bnt
\bt-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs-
\b-h
\bho
\bor
\bri
\biz
\bzo
\bon
\bnt
\bta
\bal
\bll
\bly
\by (
\b(O
\bOf
\bff
\bf)
\b)
3033 If set to O
\bOn
\bn, readline will display completions with matches
3034 sorted horizontally in alphabetical order, rather than down the
3036 r
\bre
\bev
\bve
\ber
\brt
\bt-
\b-a
\bal
\bll
\bl-
\b-a
\bat
\bt-
\b-n
\bne
\bew
\bwl
\bli
\bin
\bne
\be (
\b(O
\bOf
\bff
\bf)
\b)
3037 If set to O
\bOn
\bn, readline will undo all changes to history lines
3038 before returning when a
\bac
\bcc
\bce
\bep
\bpt
\bt-
\b-l
\bli
\bin
\bne
\be is executed. By default, his-
3039 tory lines may be modified and retain individual undo lists
3040 across calls to r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be.
3041 s
\bsh
\bho
\bow
\bw-
\b-a
\bal
\bll
\bl-
\b-i
\bif
\bf-
\b-a
\bam
\bmb
\bbi
\big
\bgu
\buo
\bou
\bus
\bs (
\b(O
\bOf
\bff
\bf)
\b)
3042 This alters the default behavior of the completion functions.
3043 If set to O
\bOn
\bn, words which have more than one possible completion
3044 cause the matches to be listed immediately instead of ringing
3046 s
\bsh
\bho
\bow
\bw-
\b-a
\bal
\bll
\bl-
\b-i
\bif
\bf-
\b-u
\bun
\bnm
\bmo
\bod
\bdi
\bif
\bfi
\bie
\bed
\bd (
\b(O
\bOf
\bff
\bf)
\b)
3047 This alters the default behavior of the completion functions in
3048 a fashion similar to s
\bsh
\bho
\bow
\bw-
\b-a
\bal
\bll
\bl-
\b-i
\bif
\bf-
\b-a
\bam
\bmb
\bbi
\big
\bgu
\buo
\bou
\bus
\bs. If set to O
\bOn
\bn, words
3049 which have more than one possible completion without any possi-
3050 ble partial completion (the possible completions don't share a
3051 common prefix) cause the matches to be listed immediately
3052 instead of ringing the bell.
3053 s
\bsh
\bho
\bow
\bw-
\b-m
\bmo
\bod
\bde
\be-
\b-i
\bin
\bn-
\b-p
\bpr
\bro
\bom
\bmp
\bpt
\bt (
\b(O
\bOf
\bff
\bf)
\b)
3054 If set to O
\bOn
\bn, add a character to the beginning of the prompt
3055 indicating the editing mode: emacs (@), vi command (:) or vi
3057 s
\bsk
\bki
\bip
\bp-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\bed
\bd-
\b-t
\bte
\bex
\bxt
\bt (
\b(O
\bOf
\bff
\bf)
\b)
3058 If set to O
\bOn
\bn, this alters the default completion behavior when
3059 inserting a single match into the line. It's only active when
3060 performing completion in the middle of a word. If enabled,
3061 readline does not insert characters from the completion that
3062 match characters after point in the word being completed, so
3063 portions of the word following the cursor are not duplicated.
3064 v
\bvi
\bis
\bsi
\bib
\bbl
\ble
\be-
\b-s
\bst
\bta
\bat
\bts
\bs (
\b(O
\bOf
\bff
\bf)
\b)
3065 If set to O
\bOn
\bn, a character denoting a file's type as reported by
3066 _
\bs_
\bt_
\ba_
\bt(2) is appended to the filename when listing possible com-
3069 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be C
\bCo
\bon
\bnd
\bdi
\bit
\bti
\bio
\bon
\bna
\bal
\bl C
\bCo
\bon
\bns
\bst
\btr
\bru
\buc
\bct
\bts
\bs
3070 Readline implements a facility similar in spirit to the conditional
3071 compilation features of the C preprocessor which allows key bindings
3072 and variable settings to be performed as the result of tests. There
3073 are four parser directives used.
3075 $
\b$i
\bif
\bf The $
\b$i
\bif
\bf construct allows bindings to be made based on the edit-
3076 ing mode, the terminal being used, or the application using
3077 readline. The text of the test extends to the end of the line;
3078 no characters are required to isolate it.
3080 m
\bmo
\bod
\bde
\be The m
\bmo
\bod
\bde
\be=
\b= form of the $
\b$i
\bif
\bf directive is used to test
3081 whether readline is in emacs or vi mode. This may be
3082 used in conjunction with the s
\bse
\bet
\bt k
\bke
\bey
\bym
\bma
\bap
\bp command, for
3083 instance, to set bindings in the _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd and
3084 _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bc_
\bt_
\bl_
\bx keymaps only if readline is starting out in
3087 t
\bte
\ber
\brm
\bm The t
\bte
\ber
\brm
\bm=
\b= form may be used to include terminal-specific
3088 key bindings, perhaps to bind the key sequences output by
3089 the terminal's function keys. The word on the right side
3090 of the =
\b= is tested against the both full name of the ter-
3091 minal and the portion of the terminal name before the
3092 first -
\b-. This allows _
\bs_
\bu_
\bn to match both _
\bs_
\bu_
\bn and _
\bs_
\bu_
\bn_
\b-_
\bc_
\bm_
\bd,
3095 a
\bap
\bpp
\bpl
\bli
\bic
\bca
\bat
\bti
\bio
\bon
\bn
3096 The a
\bap
\bpp
\bpl
\bli
\bic
\bca
\bat
\bti
\bio
\bon
\bn construct is used to include application-
3097 specific settings. Each program using the readline
3098 library sets the _
\ba_
\bp_
\bp_
\bl_
\bi_
\bc_
\ba_
\bt_
\bi_
\bo_
\bn _
\bn_
\ba_
\bm_
\be, and an initialization
3099 file can test for a particular value. This could be used
3100 to bind key sequences to functions useful for a specific
3101 program. For instance, the following command adds a key
3102 sequence that quotes the current or previous word in
3106 # Quote the current or previous word
3107 "\C-xq": "\eb\"\ef\""
3108 $
\b$e
\ben
\bnd
\bdi
\bif
\bf
3110 $
\b$e
\ben
\bnd
\bdi
\bif
\bf This command, as seen in the previous example, terminates an $
\b$i
\bif
\bf
3113 $
\b$e
\bel
\bls
\bse
\be Commands in this branch of the $
\b$i
\bif
\bf directive are executed if the
3116 $
\b$i
\bin
\bnc
\bcl
\blu
\bud
\bde
\be
3117 This directive takes a single filename as an argument and reads
3118 commands and bindings from that file. For example, the follow-
3119 ing directive would read _
\b/_
\be_
\bt_
\bc_
\b/_
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc:
3121 $
\b$i
\bin
\bnc
\bcl
\blu
\bud
\bde
\be _
\b/_
\be_
\bt_
\bc_
\b/_
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc
3123 S
\bSe
\bea
\bar
\brc
\bch
\bhi
\bin
\bng
\bg
3124 Readline provides commands for searching through the command history
3125 (see H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY below) for lines containing a specified string. There are
3126 two search modes: _
\bi_
\bn_
\bc_
\br_
\be_
\bm_
\be_
\bn_
\bt_
\ba_
\bl and _
\bn_
\bo_
\bn_
\b-_
\bi_
\bn_
\bc_
\br_
\be_
\bm_
\be_
\bn_
\bt_
\ba_
\bl.
3128 Incremental searches begin before the user has finished typing the
3129 search string. As each character of the search string is typed, read-
3130 line displays the next entry from the history matching the string typed
3131 so far. An incremental search requires only as many characters as
3132 needed to find the desired history entry. The characters present in
3133 the value of the i
\bis
\bse
\bea
\bar
\brc
\bch
\bh-
\b-t
\bte
\ber
\brm
\bmi
\bin
\bna
\bat
\bto
\bor
\brs
\bs variable are used to terminate an
3134 incremental search. If that variable has not been assigned a value the
3135 Escape and Control-J characters will terminate an incremental search.
3136 Control-G will abort an incremental search and restore the original
3137 line. When the search is terminated, the history entry containing the
3138 search string becomes the current line.
3140 To find other matching entries in the history list, type Control-S or
3141 Control-R as appropriate. This will search backward or forward in the
3142 history for the next entry matching the search string typed so far.
3143 Any other key sequence bound to a readline command will terminate the
3144 search and execute that command. For instance, a _
\bn_
\be_
\bw_
\bl_
\bi_
\bn_
\be will termi-
3145 nate the search and accept the line, thereby executing the command from
3148 Readline remembers the last incremental search string. If two Control-
3149 Rs are typed without any intervening characters defining a new search
3150 string, any remembered search string is used.
3152 Non-incremental searches read the entire search string before starting
3153 to search for matching history lines. The search string may be typed
3154 by the user or be part of the contents of the current line.
3156 R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bd N
\bNa
\bam
\bme
\bes
\bs
3157 The following is a list of the names of the commands and the default
3158 key sequences to which they are bound. Command names without an accom-
3159 panying key sequence are unbound by default. In the following descrip-
3160 tions, _
\bp_
\bo_
\bi_
\bn_
\bt refers to the current cursor position, and _
\bm_
\ba_
\br_
\bk refers to
3161 a cursor position saved by the s
\bse
\bet
\bt-
\b-m
\bma
\bar
\brk
\bk command. The text between the
3162 point and mark is referred to as the _
\br_
\be_
\bg_
\bi_
\bo_
\bn.
3164 C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs f
\bfo
\bor
\br M
\bMo
\bov
\bvi
\bin
\bng
\bg
3165 b
\bbe
\beg
\bgi
\bin
\bnn
\bni
\bin
\bng
\bg-
\b-o
\bof
\bf-
\b-l
\bli
\bin
\bne
\be (
\b(C
\bC-
\b-a
\ba)
\b)
3166 Move to the start of the current line.
3167 e
\ben
\bnd
\bd-
\b-o
\bof
\bf-
\b-l
\bli
\bin
\bne
\be (
\b(C
\bC-
\b-e
\be)
\b)
3168 Move to the end of the line.
3169 f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-c
\bch
\bha
\bar
\br (
\b(C
\bC-
\b-f
\bf)
\b)
3170 Move forward a character.
3171 b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-c
\bch
\bha
\bar
\br (
\b(C
\bC-
\b-b
\bb)
\b)
3172 Move back a character.
3173 f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-f
\bf)
\b)
3174 Move forward to the end of the next word. Words are composed of
3175 alphanumeric characters (letters and digits).
3176 b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-b
\bb)
\b)
3177 Move back to the start of the current or previous word. Words
3178 are composed of alphanumeric characters (letters and digits).
3179 s
\bsh
\bhe
\bel
\bll
\bl-
\b-f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd
3180 Move forward to the end of the next word. Words are delimited
3181 by non-quoted shell metacharacters.
3182 s
\bsh
\bhe
\bel
\bll
\bl-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd
3183 Move back to the start of the current or previous word. Words
3184 are delimited by non-quoted shell metacharacters.
3185 c
\bcl
\ble
\bea
\bar
\br-
\b-s
\bsc
\bcr
\bre
\bee
\ben
\bn (
\b(C
\bC-
\b-l
\bl)
\b)
3186 Clear the screen leaving the current line at the top of the
3187 screen. With an argument, refresh the current line without
3188 clearing the screen.
3189 r
\bre
\bed
\bdr
\bra
\baw
\bw-
\b-c
\bcu
\bur
\brr
\bre
\ben
\bnt
\bt-
\b-l
\bli
\bin
\bne
\be
3190 Refresh the current line.
3192 C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs f
\bfo
\bor
\br M
\bMa
\ban
\bni
\bip
\bpu
\bul
\bla
\bat
\bti
\bin
\bng
\bg t
\bth
\bhe
\be H
\bHi
\bis
\bst
\bto
\bor
\bry
\by
3193 a
\bac
\bcc
\bce
\bep
\bpt
\bt-
\b-l
\bli
\bin
\bne
\be (
\b(N
\bNe
\bew
\bwl
\bli
\bin
\bne
\be,
\b, R
\bRe
\bet
\btu
\bur
\brn
\bn)
\b)
3194 Accept the line regardless of where the cursor is. If this line
3195 is non-empty, add it to the history list according to the state
3196 of the H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL variable. If the line is a modified history
3197 line, then restore the history line to its original state.
3198 p
\bpr
\bre
\bev
\bvi
\bio
\bou
\bus
\bs-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(C
\bC-
\b-p
\bp)
\b)
3199 Fetch the previous command from the history list, moving back in
3201 n
\bne
\bex
\bxt
\bt-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(C
\bC-
\b-n
\bn)
\b)
3202 Fetch the next command from the history list, moving forward in
3204 b
\bbe
\beg
\bgi
\bin
\bnn
\bni
\bin
\bng
\bg-
\b-o
\bof
\bf-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(M
\bM-
\b-<
\b<)
\b)
3205 Move to the first line in the history.
3206 e
\ben
\bnd
\bd-
\b-o
\bof
\bf-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(M
\bM-
\b->
\b>)
\b)
3207 Move to the end of the input history, i.e., the line currently
3209 r
\bre
\bev
\bve
\ber
\brs
\bse
\be-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(C
\bC-
\b-r
\br)
\b)
3210 Search backward starting at the current line and moving `up'
3211 through the history as necessary. This is an incremental
3213 f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(C
\bC-
\b-s
\bs)
\b)
3214 Search forward starting at the current line and moving `down'
3215 through the history as necessary. This is an incremental
3217 n
\bno
\bon
\bn-
\b-i
\bin
\bnc
\bcr
\bre
\bem
\bme
\ben
\bnt
\bta
\bal
\bl-
\b-r
\bre
\bev
\bve
\ber
\brs
\bse
\be-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(M
\bM-
\b-p
\bp)
\b)
3218 Search backward through the history starting at the current line
3219 using a non-incremental search for a string supplied by the
3221 n
\bno
\bon
\bn-
\b-i
\bin
\bnc
\bcr
\bre
\bem
\bme
\ben
\bnt
\bta
\bal
\bl-
\b-f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(M
\bM-
\b-n
\bn)
\b)
3222 Search forward through the history using a non-incremental
3223 search for a string supplied by the user.
3224 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd
3225 Search forward through the history for the string of characters
3226 between the start of the current line and the point. This is a
3227 non-incremental search.
3228 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd
3229 Search backward through the history for the string of characters
3230 between the start of the current line and the point. This is a
3231 non-incremental search.
3232 y
\bya
\ban
\bnk
\bk-
\b-n
\bnt
\bth
\bh-
\b-a
\bar
\brg
\bg (
\b(M
\bM-
\b-C
\bC-
\b-y
\by)
\b)
3233 Insert the first argument to the previous command (usually the
3234 second word on the previous line) at point. With an argument _
\bn,
3235 insert the _
\bnth word from the previous command (the words in the
3236 previous command begin with word 0). A negative argument
3237 inserts the _
\bnth word from the end of the previous command. Once
3238 the argument _
\bn is computed, the argument is extracted as if the
3239 "!_
\bn" history expansion had been specified.
3240 y
\bya
\ban
\bnk
\bk-
\b-l
\bla
\bas
\bst
\bt-
\b-a
\bar
\brg
\bg (
\b(M
\bM-
\b-.
\b.,
\b, M
\bM-
\b-_
\b_)
\b)
3241 Insert the last argument to the previous command (the last word
3242 of the previous history entry). With a numeric argument, behave
3243 exactly like y
\bya
\ban
\bnk
\bk-
\b-n
\bnt
\bth
\bh-
\b-a
\bar
\brg
\bg. Successive calls to y
\bya
\ban
\bnk
\bk-
\b-l
\bla
\bas
\bst
\bt-
\b-a
\bar
\brg
\bg
3244 move back through the history list, inserting the last word (or
3245 the word specified by the argument to the first call) of each
3246 line in turn. Any numeric argument supplied to these successive
3247 calls determines the direction to move through the history. A
3248 negative argument switches the direction through the history
3249 (back or forward). The history expansion facilities are used to
3250 extract the last word, as if the "!$" history expansion had been
3252 s
\bsh
\bhe
\bel
\bll
\bl-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-l
\bli
\bin
\bne
\be (
\b(M
\bM-
\b-C
\bC-
\b-e
\be)
\b)
3253 Expand the line as the shell does. This performs alias and his-
3254 tory expansion as well as all of the shell word expansions. See
3255 H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below for a description of history expansion.
3256 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-l
\bli
\bin
\bne
\be (
\b(M
\bM-
\b-^
\b^)
\b)
3257 Perform history expansion on the current line. See H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY
3258 E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below for a description of history expansion.
3259 m
\bma
\bag
\bgi
\bic
\bc-
\b-s
\bsp
\bpa
\bac
\bce
\be
3260 Perform history expansion on the current line and insert a
3261 space. See H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN below for a description of history
3263 a
\bal
\bli
\bia
\bas
\bs-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-l
\bli
\bin
\bne
\be
3264 Perform alias expansion on the current line. See A
\bAL
\bLI
\bIA
\bAS
\bSE
\bES
\bS above
3265 for a description of alias expansion.
3266 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by-
\b-a
\ban
\bnd
\bd-
\b-a
\bal
\bli
\bia
\bas
\bs-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-l
\bli
\bin
\bne
\be
3267 Perform history and alias expansion on the current line.
3268 i
\bin
\bns
\bse
\ber
\brt
\bt-
\b-l
\bla
\bas
\bst
\bt-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt (
\b(M
\bM-
\b-.
\b.,
\b, M
\bM-
\b-_
\b_)
\b)
3269 A synonym for y
\bya
\ban
\bnk
\bk-
\b-l
\bla
\bas
\bst
\bt-
\b-a
\bar
\brg
\bg.
3270 o
\bop
\bpe
\ber
\bra
\bat
\bte
\be-
\b-a
\ban
\bnd
\bd-
\b-g
\bge
\bet
\bt-
\b-n
\bne
\bex
\bxt
\bt (
\b(C
\bC-
\b-o
\bo)
\b)
3271 Accept the current line for execution and fetch the next line
3272 relative to the current line from the history for editing. Any
3273 argument is ignored.
3274 e
\bed
\bdi
\bit
\bt-
\b-a
\ban
\bnd
\bd-
\b-e
\bex
\bxe
\bec
\bcu
\but
\bte
\be-
\b-c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd (
\b(C
\bC-
\b-x
\bxC
\bC-
\b-e
\be)
\b)
3275 Invoke an editor on the current command line, and execute the
3276 result as shell commands. B
\bBa
\bas
\bsh
\bh attempts to invoke $
\b$V
\bVI
\bIS
\bSU
\bUA
\bAL
\bL,
3277 $
\b$E
\bED
\bDI
\bIT
\bTO
\bOR
\bR, and _
\be_
\bm_
\ba_
\bc_
\bs as the editor, in that order.
3279 C
\bCo
\bom
\bmm
\bma
\ban
\bnd
\bds
\bs f
\bfo
\bor
\br C
\bCh
\bha
\ban
\bng
\bgi
\bin
\bng
\bg T
\bTe
\bex
\bxt
\bt
3280 _
\be_
\bn_
\bd_
\b-_
\bo_
\bf_
\b-_
\bf_
\bi_
\bl_
\be (
\b(u
\bus
\bsu
\bua
\bal
\bll
\bly
\by C
\bC-
\b-d
\bd)
\b)
3281 The character indicating end-of-file as set, for example, by
3282 ``stty''. If this character is read when there are no charac-
3283 ters on the line, and point is at the beginning of the line,
3284 Readline interprets it as the end of input and returns E
\bEO
\bOF
\bF.
3285 d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br (
\b(C
\bC-
\b-d
\bd)
\b)
3286 Delete the character at point. If this function is bound to the
3287 same character as the tty E
\bEO
\bOF
\bF character, as C
\bC-
\b-d
\bd commonly is, see
3288 above for the effects.
3289 b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br (
\b(R
\bRu
\bub
\bbo
\bou
\but
\bt)
\b)
3290 Delete the character behind the cursor. When given a numeric
3291 argument, save the deleted text on the kill ring.
3292 f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br
3293 Delete the character under the cursor, unless the cursor is at
3294 the end of the line, in which case the character behind the cur-
3296 q
\bqu
\buo
\bot
\bte
\bed
\bd-
\b-i
\bin
\bns
\bse
\ber
\brt
\bt (
\b(C
\bC-
\b-q
\bq,
\b, C
\bC-
\b-v
\bv)
\b)
3297 Add the next character typed to the line verbatim. This is how
3298 to insert characters like C
\bC-
\b-q
\bq, for example.
3299 t
\bta
\bab
\bb-
\b-i
\bin
\bns
\bse
\ber
\brt
\bt (
\b(C
\bC-
\b-v
\bv T
\bTA
\bAB
\bB)
\b)
3300 Insert a tab character.
3301 s
\bse
\bel
\blf
\bf-
\b-i
\bin
\bns
\bse
\ber
\brt
\bt (
\b(a
\ba,
\b, b
\bb,
\b, A
\bA,
\b, 1
\b1,
\b, !
\b!,
\b, .
\b..
\b..
\b.)
\b)
3302 Insert the character typed.
3303 t
\btr
\bra
\ban
\bns
\bsp
\bpo
\bos
\bse
\be-
\b-c
\bch
\bha
\bar
\brs
\bs (
\b(C
\bC-
\b-t
\bt)
\b)
3304 Drag the character before point forward over the character at
3305 point, moving point forward as well. If point is at the end of
3306 the line, then this transposes the two characters before point.
3307 Negative arguments have no effect.
3308 t
\btr
\bra
\ban
\bns
\bsp
\bpo
\bos
\bse
\be-
\b-w
\bwo
\bor
\brd
\bds
\bs (
\b(M
\bM-
\b-t
\bt)
\b)
3309 Drag the word before point past the word after point, moving
3310 point over that word as well. If point is at the end of the
3311 line, this transposes the last two words on the line.
3312 u
\bup
\bpc
\bca
\bas
\bse
\be-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-u
\bu)
\b)
3313 Uppercase the current (or following) word. With a negative
3314 argument, uppercase the previous word, but do not move point.
3315 d
\bdo
\bow
\bwn
\bnc
\bca
\bas
\bse
\be-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-l
\bl)
\b)
3316 Lowercase the current (or following) word. With a negative
3317 argument, lowercase the previous word, but do not move point.
3318 c
\bca
\bap
\bpi
\bit
\bta
\bal
\bli
\biz
\bze
\be-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-c
\bc)
\b)
3319 Capitalize the current (or following) word. With a negative
3320 argument, capitalize the previous word, but do not move point.
3321 o
\bov
\bve
\ber
\brw
\bwr
\bri
\bit
\bte
\be-
\b-m
\bmo
\bod
\bde
\be
3322 Toggle overwrite mode. With an explicit positive numeric argu-
3323 ment, switches to overwrite mode. With an explicit non-positive
3324 numeric argument, switches to insert mode. This command affects
3325 only e
\bem
\bma
\bac
\bcs
\bs mode; v
\bvi
\bi mode does overwrite differently. Each call
3326 to _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be_
\b(_
\b) starts in insert mode. In overwrite mode, charac-
3327 ters bound to s
\bse
\bel
\blf
\bf-
\b-i
\bin
\bns
\bse
\ber
\brt
\bt replace the text at point rather than
3328 pushing the text to the right. Characters bound to b
\bba
\bac
\bck
\bk-
\b-
3329 w
\bwa
\bar
\brd
\bd-
\b-d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br replace the character before point with a
3330 space. By default, this command is unbound.
3332 K
\bKi
\bil
\bll
\bli
\bin
\bng
\bg a
\ban
\bnd
\bd Y
\bYa
\ban
\bnk
\bki
\bin
\bng
\bg
3333 k
\bki
\bil
\bll
\bl-
\b-l
\bli
\bin
\bne
\be (
\b(C
\bC-
\b-k
\bk)
\b)
3334 Kill the text from point to the end of the line.
3335 b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-k
\bki
\bil
\bll
\bl-
\b-l
\bli
\bin
\bne
\be (
\b(C
\bC-
\b-x
\bx R
\bRu
\bub
\bbo
\bou
\but
\bt)
\b)
3336 Kill backward to the beginning of the line.
3337 u
\bun
\bni
\bix
\bx-
\b-l
\bli
\bin
\bne
\be-
\b-d
\bdi
\bis
\bsc
\bca
\bar
\brd
\bd (
\b(C
\bC-
\b-u
\bu)
\b)
3338 Kill backward from point to the beginning of the line. The
3339 killed text is saved on the kill-ring.
3340 k
\bki
\bil
\bll
\bl-
\b-w
\bwh
\bho
\bol
\ble
\be-
\b-l
\bli
\bin
\bne
\be
3341 Kill all characters on the current line, no matter where point
3343 k
\bki
\bil
\bll
\bl-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-d
\bd)
\b)
3344 Kill from point to the end of the current word, or if between
3345 words, to the end of the next word. Word boundaries are the
3346 same as those used by f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3347 b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-k
\bki
\bil
\bll
\bl-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-R
\bRu
\bub
\bbo
\bou
\but
\bt)
\b)
3348 Kill the word behind point. Word boundaries are the same as
3349 those used by b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3350 s
\bsh
\bhe
\bel
\bll
\bl-
\b-k
\bki
\bil
\bll
\bl-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-d
\bd)
\b)
3351 Kill from point to the end of the current word, or if between
3352 words, to the end of the next word. Word boundaries are the
3353 same as those used by s
\bsh
\bhe
\bel
\bll
\bl-
\b-f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3354 s
\bsh
\bhe
\bel
\bll
\bl-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-k
\bki
\bil
\bll
\bl-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-R
\bRu
\bub
\bbo
\bou
\but
\bt)
\b)
3355 Kill the word behind point. Word boundaries are the same as
3356 those used by s
\bsh
\bhe
\bel
\bll
\bl-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3357 u
\bun
\bni
\bix
\bx-
\b-w
\bwo
\bor
\brd
\bd-
\b-r
\bru
\bub
\bbo
\bou
\but
\bt (
\b(C
\bC-
\b-w
\bw)
\b)
3358 Kill the word behind point, using white space as a word bound-
3359 ary. The killed text is saved on the kill-ring.
3360 u
\bun
\bni
\bix
\bx-
\b-f
\bfi
\bil
\ble
\ben
\bna
\bam
\bme
\be-
\b-r
\bru
\bub
\bbo
\bou
\but
\bt
3361 Kill the word behind point, using white space and the slash
3362 character as the word boundaries. The killed text is saved on
3364 d
\bde
\bel
\ble
\bet
\bte
\be-
\b-h
\bho
\bor
\bri
\biz
\bzo
\bon
\bnt
\bta
\bal
\bl-
\b-s
\bsp
\bpa
\bac
\bce
\be (
\b(M
\bM-
\b-\
\b\)
\b)
3365 Delete all spaces and tabs around point.
3366 k
\bki
\bil
\bll
\bl-
\b-r
\bre
\beg
\bgi
\bio
\bon
\bn
3367 Kill the text in the current region.
3368 c
\bco
\bop
\bpy
\by-
\b-r
\bre
\beg
\bgi
\bio
\bon
\bn-
\b-a
\bas
\bs-
\b-k
\bki
\bil
\bll
\bl
3369 Copy the text in the region to the kill buffer.
3370 c
\bco
\bop
\bpy
\by-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd
3371 Copy the word before point to the kill buffer. The word bound-
3372 aries are the same as b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3373 c
\bco
\bop
\bpy
\by-
\b-f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd
3374 Copy the word following point to the kill buffer. The word
3375 boundaries are the same as f
\bfo
\bor
\brw
\bwa
\bar
\brd
\bd-
\b-w
\bwo
\bor
\brd
\bd.
3376 y
\bya
\ban
\bnk
\bk (
\b(C
\bC-
\b-y
\by)
\b)
3377 Yank the top of the kill ring into the buffer at point.
3378 y
\bya
\ban
\bnk
\bk-
\b-p
\bpo
\bop
\bp (
\b(M
\bM-
\b-y
\by)
\b)
3379 Rotate the kill ring, and yank the new top. Only works follow-
3380 ing y
\bya
\ban
\bnk
\bk or y
\bya
\ban
\bnk
\bk-
\b-p
\bpo
\bop
\bp.
3382 N
\bNu
\bum
\bme
\ber
\bri
\bic
\bc A
\bAr
\brg
\bgu
\bum
\bme
\ben
\bnt
\bts
\bs
3383 d
\bdi
\big
\bgi
\bit
\bt-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt (
\b(M
\bM-
\b-0
\b0,
\b, M
\bM-
\b-1
\b1,
\b, .
\b..
\b..
\b.,
\b, M
\bM-
\b--
\b-)
\b)
3384 Add this digit to the argument already accumulating, or start a
3385 new argument. M-- starts a negative argument.
3386 u
\bun
\bni
\biv
\bve
\ber
\brs
\bsa
\bal
\bl-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt
3387 This is another way to specify an argument. If this command is
3388 followed by one or more digits, optionally with a leading minus
3389 sign, those digits define the argument. If the command is fol-
3390 lowed by digits, executing u
\bun
\bni
\biv
\bve
\ber
\brs
\bsa
\bal
\bl-
\b-a
\bar
\brg
\bgu
\bum
\bme
\ben
\bnt
\bt again ends the
3391 numeric argument, but is otherwise ignored. As a special case,
3392 if this command is immediately followed by a character that is
3393 neither a digit or minus sign, the argument count for the next
3394 command is multiplied by four. The argument count is initially
3395 one, so executing this function the first time makes the argu-
3396 ment count four, a second time makes the argument count sixteen,
3399 C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bin
\bng
\bg
3400 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be (
\b(T
\bTA
\bAB
\bB)
\b)
3401 Attempt to perform completion on the text before point. B
\bBa
\bas
\bsh
\bh
3402 attempts completion treating the text as a variable (if the text
3403 begins with $
\b$), username (if the text begins with ~
\b~), hostname
3404 (if the text begins with @
\b@), or command (including aliases and
3405 functions) in turn. If none of these produces a match, filename
3406 completion is attempted.
3407 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(M
\bM-
\b-?
\b?)
\b)
3408 List the possible completions of the text before point.
3409 i
\bin
\bns
\bse
\ber
\brt
\bt-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(M
\bM-
\b-*
\b*)
\b)
3410 Insert all completions of the text before point that would have
3411 been generated by p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs.
3412 m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be
3413 Similar to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be, but replaces the word to be completed with
3414 a single match from the list of possible completions. Repeated
3415 execution of m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be steps through the list of possible
3416 completions, inserting each match in turn. At the end of the
3417 list of completions, the bell is rung (subject to the setting of
3418 b
\bbe
\bel
\bll
\bl-
\b-s
\bst
\bty
\byl
\ble
\be) and the original text is restored. An argument of _
\bn
3419 moves _
\bn positions forward in the list of matches; a negative
3420 argument may be used to move backward through the list. This
3421 command is intended to be bound to T
\bTA
\bAB
\bB, but is unbound by
3423 m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd
3424 Identical to m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be, but moves backward through the list
3425 of possible completions, as if m
\bme
\ben
\bnu
\bu-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be had been given a
3426 negative argument. This command is unbound by default.
3427 d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br-
\b-o
\bor
\br-
\b-l
\bli
\bis
\bst
\bt
3428 Deletes the character under the cursor if not at the beginning
3429 or end of the line (like d
\bde
\bel
\ble
\bet
\bte
\be-
\b-c
\bch
\bha
\bar
\br). If at the end of the
3430 line, behaves identically to p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs. This command
3431 is unbound by default.
3432 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-f
\bfi
\bil
\ble
\ben
\bna
\bam
\bme
\be (
\b(M
\bM-
\b-/
\b/)
\b)
3433 Attempt filename completion on the text before point.
3434 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-f
\bfi
\bil
\ble
\ben
\bna
\bam
\bme
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx /
\b/)
\b)
3435 List the possible completions of the text before point, treating
3437 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-u
\bus
\bse
\ber
\brn
\bna
\bam
\bme
\be (
\b(M
\bM-
\b-~
\b~)
\b)
3438 Attempt completion on the text before point, treating it as a
3440 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-u
\bus
\bse
\ber
\brn
\bna
\bam
\bme
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx ~
\b~)
\b)
3441 List the possible completions of the text before point, treating
3443 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-v
\bva
\bar
\bri
\bia
\bab
\bbl
\ble
\be (
\b(M
\bM-
\b-$
\b$)
\b)
3444 Attempt completion on the text before point, treating it as a
3446 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-v
\bva
\bar
\bri
\bia
\bab
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx $
\b$)
\b)
3447 List the possible completions of the text before point, treating
3448 it as a shell variable.
3449 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-h
\bho
\bos
\bst
\btn
\bna
\bam
\bme
\be (
\b(M
\bM-
\b-@
\b@)
\b)
3450 Attempt completion on the text before point, treating it as a
3452 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-h
\bho
\bos
\bst
\btn
\bna
\bam
\bme
\be-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx @
\b@)
\b)
3453 List the possible completions of the text before point, treating
3455 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd (
\b(M
\bM-
\b-!
\b!)
\b)
3456 Attempt completion on the text before point, treating it as a
3457 command name. Command completion attempts to match the text
3458 against aliases, reserved words, shell functions, shell
3459 builtins, and finally executable filenames, in that order.
3460 p
\bpo
\bos
\bss
\bsi
\bib
\bbl
\ble
\be-
\b-c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx !
\b!)
\b)
3461 List the possible completions of the text before point, treating
3462 it as a command name.
3463 d
\bdy
\byn
\bna
\bam
\bmi
\bic
\bc-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-h
\bhi
\bis
\bst
\bto
\bor
\bry
\by (
\b(M
\bM-
\b-T
\bTA
\bAB
\bB)
\b)
3464 Attempt completion on the text before point, comparing the text
3465 against lines from the history list for possible completion
3467 d
\bda
\bab
\bbb
\bbr
\bre
\bev
\bv-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd
3468 Attempt menu completion on the text before point, comparing the
3469 text against lines from the history list for possible completion
3471 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-i
\bin
\bnt
\bto
\bo-
\b-b
\bbr
\bra
\bac
\bce
\bes
\bs (
\b(M
\bM-
\b-{
\b{)
\b)
3472 Perform filename completion and insert the list of possible com-
3473 pletions enclosed within braces so the list is available to the
3474 shell (see B
\bBr
\bra
\bac
\bce
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn above).
3476 K
\bKe
\bey
\byb
\bbo
\boa
\bar
\brd
\bd M
\bMa
\bac
\bcr
\bro
\bos
\bs
3477 s
\bst
\bta
\bar
\brt
\bt-
\b-k
\bkb
\bbd
\bd-
\b-m
\bma
\bac
\bcr
\bro
\bo (
\b(C
\bC-
\b-x
\bx (
\b()
\b)
3478 Begin saving the characters typed into the current keyboard
3480 e
\ben
\bnd
\bd-
\b-k
\bkb
\bbd
\bd-
\b-m
\bma
\bac
\bcr
\bro
\bo (
\b(C
\bC-
\b-x
\bx )
\b))
\b)
3481 Stop saving the characters typed into the current keyboard macro
3482 and store the definition.
3483 c
\bca
\bal
\bll
\bl-
\b-l
\bla
\bas
\bst
\bt-
\b-k
\bkb
\bbd
\bd-
\b-m
\bma
\bac
\bcr
\bro
\bo (
\b(C
\bC-
\b-x
\bx e
\be)
\b)
3484 Re-execute the last keyboard macro defined, by making the char-
3485 acters in the macro appear as if typed at the keyboard.
3486 p
\bpr
\bri
\bin
\bnt
\bt-
\b-l
\bla
\bas
\bst
\bt-
\b-k
\bkb
\bbd
\bd-
\b-m
\bma
\bac
\bcr
\bro
\bo (
\b()
\b)
3487 Print the last keyboard macro defined in a format suitable for
3488 the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file.
3490 M
\bMi
\bis
\bsc
\bce
\bel
\bll
\bla
\ban
\bne
\beo
\bou
\bus
\bs
3491 r
\bre
\be-
\b-r
\bre
\bea
\bad
\bd-
\b-i
\bin
\bni
\bit
\bt-
\b-f
\bfi
\bil
\ble
\be (
\b(C
\bC-
\b-x
\bx C
\bC-
\b-r
\br)
\b)
3492 Read in the contents of the _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file, and incorporate any
3493 bindings or variable assignments found there.
3494 a
\bab
\bbo
\bor
\brt
\bt (
\b(C
\bC-
\b-g
\bg)
\b)
3495 Abort the current editing command and ring the terminal's bell
3496 (subject to the setting of b
\bbe
\bel
\bll
\bl-
\b-s
\bst
\bty
\byl
\ble
\be).
3497 d
\bdo
\bo-
\b-u
\bup
\bpp
\bpe
\ber
\brc
\bca
\bas
\bse
\be-
\b-v
\bve
\ber
\brs
\bsi
\bio
\bon
\bn (
\b(M
\bM-
\b-a
\ba,
\b, M
\bM-
\b-b
\bb,
\b, M
\bM-
\b-_
\bx,
\b, .
\b..
\b..
\b.)
\b)
3498 If the metafied character _
\bx is lowercase, run the command that
3499 is bound to the corresponding uppercase character.
3500 p
\bpr
\bre
\bef
\bfi
\bix
\bx-
\b-m
\bme
\bet
\bta
\ba (
\b(E
\bES
\bSC
\bC)
\b)
3501 Metafy the next character typed. E
\bES
\bSC
\bC f
\bf is equivalent to M
\bMe
\bet
\bta
\ba-
\b-f
\bf.
3502 u
\bun
\bnd
\bdo
\bo (
\b(C
\bC-
\b-_
\b_,
\b, C
\bC-
\b-x
\bx C
\bC-
\b-u
\bu)
\b)
3503 Incremental undo, separately remembered for each line.
3504 r
\bre
\bev
\bve
\ber
\brt
\bt-
\b-l
\bli
\bin
\bne
\be (
\b(M
\bM-
\b-r
\br)
\b)
3505 Undo all changes made to this line. This is like executing the
3506 u
\bun
\bnd
\bdo
\bo command enough times to return the line to its initial
3508 t
\bti
\bil
\bld
\bde
\be-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd (
\b(M
\bM-
\b-&
\b&)
\b)
3509 Perform tilde expansion on the current word.
3510 s
\bse
\bet
\bt-
\b-m
\bma
\bar
\brk
\bk (
\b(C
\bC-
\b-@
\b@,
\b, M
\bM-
\b-<
\b<s
\bsp
\bpa
\bac
\bce
\be>
\b>)
\b)
3511 Set the mark to the point. If a numeric argument is supplied,
3512 the mark is set to that position.
3513 e
\bex
\bxc
\bch
\bha
\ban
\bng
\bge
\be-
\b-p
\bpo
\boi
\bin
\bnt
\bt-
\b-a
\ban
\bnd
\bd-
\b-m
\bma
\bar
\brk
\bk (
\b(C
\bC-
\b-x
\bx C
\bC-
\b-x
\bx)
\b)
3514 Swap the point with the mark. The current cursor position is
3515 set to the saved position, and the old cursor position is saved
3517 c
\bch
\bha
\bar
\bra
\bac
\bct
\bte
\ber
\br-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh (
\b(C
\bC-
\b-]
\b])
\b)
3518 A character is read and point is moved to the next occurrence of
3519 that character. A negative count searches for previous occur-
3521 c
\bch
\bha
\bar
\bra
\bac
\bct
\bte
\ber
\br-
\b-s
\bse
\bea
\bar
\brc
\bch
\bh-
\b-b
\bba
\bac
\bck
\bkw
\bwa
\bar
\brd
\bd (
\b(M
\bM-
\b-C
\bC-
\b-]
\b])
\b)
3522 A character is read and point is moved to the previous occur-
3523 rence of that character. A negative count searches for subse-
3525 s
\bsk
\bki
\bip
\bp-
\b-c
\bcs
\bsi
\bi-
\b-s
\bse
\beq
\bqu
\bue
\ben
\bnc
\bce
\be
3526 Read enough characters to consume a multi-key sequence such as
3527 those defined for keys like Home and End. Such sequences begin
3528 with a Control Sequence Indicator (CSI), usually ESC-[. If this
3529 sequence is bound to "\[", keys producing such sequences will
3530 have no effect unless explicitly bound to a readline command,
3531 instead of inserting stray characters into the editing buffer.
3532 This is unbound by default, but usually bound to ESC-[.
3533 i
\bin
\bns
\bse
\ber
\brt
\bt-
\b-c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt (
\b(M
\bM-
\b-#
\b#)
\b)
3534 Without a numeric argument, the value of the readline c
\bco
\bom
\bm-
\b-
3535 m
\bme
\ben
\bnt
\bt-
\b-b
\bbe
\beg
\bgi
\bin
\bn variable is inserted at the beginning of the current
3536 line. If a numeric argument is supplied, this command acts as a
3537 toggle: if the characters at the beginning of the line do not
3538 match the value of c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt-
\b-b
\bbe
\beg
\bgi
\bin
\bn, the value is inserted, other-
3539 wise the characters in c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt-
\b-b
\bbe
\beg
\bgi
\bin
\bn are deleted from the begin-
3540 ning of the line. In either case, the line is accepted as if a
3541 newline had been typed. The default value of c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bt-
\b-b
\bbe
\beg
\bgi
\bin
\bn
3542 causes this command to make the current line a shell comment.
3543 If a numeric argument causes the comment character to be
3544 removed, the line will be executed by the shell.
3545 g
\bgl
\blo
\bob
\bb-
\b-c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be-
\b-w
\bwo
\bor
\brd
\bd (
\b(M
\bM-
\b-g
\bg)
\b)
3546 The word before point is treated as a pattern for pathname
3547 expansion, with an asterisk implicitly appended. This pattern
3548 is used to generate a list of matching filenames for possible
3550 g
\bgl
\blo
\bob
\bb-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-w
\bwo
\bor
\brd
\bd (
\b(C
\bC-
\b-x
\bx *
\b*)
\b)
3551 The word before point is treated as a pattern for pathname
3552 expansion, and the list of matching filenames is inserted,
3553 replacing the word. If a numeric argument is supplied, an
3554 asterisk is appended before pathname expansion.
3555 g
\bgl
\blo
\bob
\bb-
\b-l
\bli
\bis
\bst
\bt-
\b-e
\bex
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bns
\bs (
\b(C
\bC-
\b-x
\bx g
\bg)
\b)
3556 The list of expansions that would have been generated by
3557 g
\bgl
\blo
\bob
\bb-
\b-e
\bex
\bxp
\bpa
\ban
\bnd
\bd-
\b-w
\bwo
\bor
\brd
\bd is displayed, and the line is redrawn. If a
3558 numeric argument is supplied, an asterisk is appended before
3560 d
\bdu
\bum
\bmp
\bp-
\b-f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bns
\bs
3561 Print all of the functions and their key bindings to the read-
3562 line output stream. If a numeric argument is supplied, the out-
3563 put is formatted in such a way that it can be made part of an
3564 _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file.
3565 d
\bdu
\bum
\bmp
\bp-
\b-v
\bva
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs
3566 Print all of the settable readline variables and their values to
3567 the readline output stream. If a numeric argument is supplied,
3568 the output is formatted in such a way that it can be made part
3569 of an _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file.
3570 d
\bdu
\bum
\bmp
\bp-
\b-m
\bma
\bac
\bcr
\bro
\bos
\bs
3571 Print all of the readline key sequences bound to macros and the
3572 strings they output. If a numeric argument is supplied, the
3573 output is formatted in such a way that it can be made part of an
3574 _
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc file.
3575 d
\bdi
\bis
\bsp
\bpl
\bla
\bay
\by-
\b-s
\bsh
\bhe
\bel
\bll
\bl-
\b-v
\bve
\ber
\brs
\bsi
\bio
\bon
\bn (
\b(C
\bC-
\b-x
\bx C
\bC-
\b-v
\bv)
\b)
3576 Display version information about the current instance of b
\bba
\bas
\bsh
\bh.
3578 P
\bPr
\bro
\bog
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn
3579 When word completion is attempted for an argument to a command for
3580 which a completion specification (a _
\bc_
\bo_
\bm_
\bp_
\bs_
\bp_
\be_
\bc) has been defined using
3581 the c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be builtin (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below), the pro-
3582 grammable completion facilities are invoked.
3584 First, the command name is identified. If the command word is the
3585 empty string (completion attempted at the beginning of an empty line),
3586 any compspec defined with the -
\b-E
\bE option to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be is used. If a
3587 compspec has been defined for that command, the compspec is used to
3588 generate the list of possible completions for the word. If the command
3589 word is a full pathname, a compspec for the full pathname is searched
3590 for first. If no compspec is found for the full pathname, an attempt
3591 is made to find a compspec for the portion following the final slash.
3592 If those searches do not result in a compspec, any compspec defined
3593 with the -
\b-D
\bD option to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be is used as the default.
3595 Once a compspec has been found, it is used to generate the list of
3596 matching words. If a compspec is not found, the default b
\bba
\bas
\bsh
\bh comple-
3597 tion as described above under C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bin
\bng
\bg is performed.
3599 First, the actions specified by the compspec are used. Only matches
3600 which are prefixed by the word being completed are returned. When the
3601 -
\b-f
\bf or -
\b-d
\bd option is used for filename or directory name completion, the
3602 shell variable F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE is used to filter the matches.
3604 Any completions specified by a pathname expansion pattern to the -
\b-G
\bG
3605 option are generated next. The words generated by the pattern need not
3606 match the word being completed. The G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE shell variable is not
3607 used to filter the matches, but the F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE variable is used.
3609 Next, the string specified as the argument to the -
\b-W
\bW option is consid-
3610 ered. The string is first split using the characters in the I
\bIF
\bFS
\bS spe-
3611 cial variable as delimiters. Shell quoting is honored. Each word is
3612 then expanded using brace expansion, tilde expansion, parameter and
3613 variable expansion, command substitution, and arithmetic expansion, as
3614 described above under E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN. The results are split using the rules
3615 described above under W
\bWo
\bor
\brd
\bd S
\bSp
\bpl
\bli
\bit
\btt
\bti
\bin
\bng
\bg. The results of the expansion are
3616 prefix-matched against the word being completed, and the matching words
3617 become the possible completions.
3619 After these matches have been generated, any shell function or command
3620 specified with the -
\b-F
\bF and -
\b-C
\bC options is invoked. When the command or
3621 function is invoked, the C
\bCO
\bOM
\bMP
\bP_
\b_L
\bLI
\bIN
\bNE
\bE, C
\bCO
\bOM
\bMP
\bP_
\b_P
\bPO
\bOI
\bIN
\bNT
\bT, C
\bCO
\bOM
\bMP
\bP_
\b_K
\bKE
\bEY
\bY, and C
\bCO
\bOM
\bMP
\bP_
\b_T
\bTY
\bYP
\bPE
\bE
3622 variables are assigned values as described above under S
\bSh
\bhe
\bel
\bll
\bl V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs.
3623 If a shell function is being invoked, the C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDS
\bS and C
\bCO
\bOM
\bMP
\bP_
\b_C
\bCW
\bWO
\bOR
\bRD
\bD
3624 variables are also set. When the function or command is invoked, the
3625 first argument ($
\b$1
\b1) is the name of the command whose arguments are
3626 being completed, the second argument ($
\b$2
\b2) is the word being completed,
3627 and the third argument ($
\b$3
\b3) is the word preceding the word being com-
3628 pleted on the current command line. No filtering of the generated com-
3629 pletions against the word being completed is performed; the function or
3630 command has complete freedom in generating the matches.
3632 Any function specified with -
\b-F
\bF is invoked first. The function may use
3633 any of the shell facilities, including the c
\bco
\bom
\bmp
\bpg
\bge
\ben
\bn builtin described
3634 below, to generate the matches. It must put the possible completions
3635 in the C
\bCO
\bOM
\bMP
\bPR
\bRE
\bEP
\bPL
\bLY
\bY array variable, one per array element.
3637 Next, any command specified with the -
\b-C
\bC option is invoked in an envi-
3638 ronment equivalent to command substitution. It should print a list of
3639 completions, one per line, to the standard output. Backslash may be
3640 used to escape a newline, if necessary.
3642 After all of the possible completions are generated, any filter speci-
3643 fied with the -
\b-X
\bX option is applied to the list. The filter is a pat-
3644 tern as used for pathname expansion; a &
\b& in the pattern is replaced
3645 with the text of the word being completed. A literal &
\b& may be escaped
3646 with a backslash; the backslash is removed before attempting a match.
3647 Any completion that matches the pattern will be removed from the list.
3648 A leading !
\b! negates the pattern; in this case any completion not match-
3649 ing the pattern will be removed.
3651 Finally, any prefix and suffix specified with the -
\b-P
\bP and -
\b-S
\bS options are
3652 added to each member of the completion list, and the result is returned
3653 to the readline completion code as the list of possible completions.
3655 If the previously-applied actions do not generate any matches, and the
3656 -
\b-o
\bo d
\bdi
\bir
\brn
\bna
\bam
\bme
\bes
\bs option was supplied to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be when the compspec was
3657 defined, directory name completion is attempted.
3659 If the -
\b-o
\bo p
\bpl
\blu
\bus
\bsd
\bdi
\bir
\brs
\bs option was supplied to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be when the compspec
3660 was defined, directory name completion is attempted and any matches are
3661 added to the results of the other actions.
3663 By default, if a compspec is found, whatever it generates is returned
3664 to the completion code as the full set of possible completions. The
3665 default b
\bba
\bas
\bsh
\bh completions are not attempted, and the readline default of
3666 filename completion is disabled. If the -
\b-o
\bo b
\bba
\bas
\bsh
\bhd
\bde
\bef
\bfa
\bau
\bul
\blt
\bt option was sup-
3667 plied to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be when the compspec was defined, the b
\bba
\bas
\bsh
\bh default com-
3668 pletions are attempted if the compspec generates no matches. If the -
\b-o
\bo
3669 d
\bde
\bef
\bfa
\bau
\bul
\blt
\bt option was supplied to c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be when the compspec was defined,
3670 readline's default completion will be performed if the compspec (and,
3671 if attempted, the default b
\bba
\bas
\bsh
\bh completions) generate no matches.
3673 When a compspec indicates that directory name completion is desired,
3674 the programmable completion functions force readline to append a slash
3675 to completed names which are symbolic links to directories, subject to
3676 the value of the m
\bma
\bar
\brk
\bk-
\b-d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bri
\bie
\bes
\bs readline variable, regardless of the
3677 setting of the m
\bma
\bar
\brk
\bk-
\b-s
\bsy
\bym
\bml
\bli
\bin
\bnk
\bke
\bed
\bd-
\b-d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bri
\bie
\bes
\bs readline variable.
3679 There is some support for dynamically modifying completions. This is
3680 most useful when used in combination with a default completion speci-
3681 fied with c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be -
\b-D
\bD. It's possible for shell functions executed as
3682 completion handlers to indicate that completion should be retried by
3683 returning an exit status of 124. If a shell function returns 124, and
3684 changes the compspec associated with the command on which completion is
3685 being attempted (supplied as the first argument when the function is
3686 executed), programmable completion restarts from the beginning, with an
3687 attempt to find a new compspec for that command. This allows a set of
3688 completions to be built dynamically as completion is attempted, rather
3689 than being loaded all at once.
3691 For instance, assuming that there is a library of compspecs, each kept
3692 in a file corresponding to the name of the command, the following
3693 default completion function would load completions dynamically:
3695 _completion_loader()
3697 . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124
3699 complete -D -F _completion_loader -o bashdefault -o default
3702 H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY
3703 When the -
\b-o
\bo h
\bhi
\bis
\bst
\bto
\bor
\bry
\by option to the s
\bse
\bet
\bt builtin is enabled, the shell
3704 provides access to the _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd _
\bh_
\bi_
\bs_
\bt_
\bo_
\br_
\by, the list of commands previously
3705 typed. The value of the H
\bHI
\bIS
\bST
\bTS
\bSI
\bIZ
\bZE
\bE variable is used as the number of
3706 commands to save in a history list. The text of the last H
\bHI
\bIS
\bST
\bTS
\bSI
\bIZ
\bZE
\bE com-
3707 mands (default 500) is saved. The shell stores each command in the
3708 history list prior to parameter and variable expansion (see E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN
3709 above) but after history expansion is performed, subject to the values
3710 of the shell variables H
\bHI
\bIS
\bST
\bTI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE and H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL.
3712 On startup, the history is initialized from the file named by the vari-
3713 able H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE (default _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bh_
\bi_
\bs_
\bt_
\bo_
\br_
\by). The file named by the value
3714 of H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE is truncated, if necessary, to contain no more than the
3715 number of lines specified by the value of H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bES
\bSI
\bIZ
\bZE
\bE. If H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE-
\b-
3716 S
\bSI
\bIZ
\bZE
\bE is unset, or set to null, a non-numeric value, or a numeric value
3717 less than zero, the history file is not truncated. When the history
3718 file is read, lines beginning with the history comment character fol-
3719 lowed immediately by a digit are interpreted as timestamps for the pre-
3720 ceding history line. These timestamps are optionally displayed depend-
3721 ing on the value of the H
\bHI
\bIS
\bST
\bTT
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT variable. When a shell with
3722 history enabled exits, the last $
\b$H
\bHI
\bIS
\bST
\bTS
\bSI
\bIZ
\bZE
\bE lines are copied from the
3723 history list to $
\b$H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE. If the h
\bhi
\bis
\bst
\bta
\bap
\bpp
\bpe
\ben
\bnd
\bd shell option is enabled
3724 (see the description of s
\bsh
\bho
\bop
\bpt
\bt under S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below), the
3725 lines are appended to the history file, otherwise the history file is
3726 overwritten. If H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE is unset, or if the history file is
3727 unwritable, the history is not saved. If the H
\bHI
\bIS
\bST
\bTT
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT variable
3728 is set, time stamps are written to the history file, marked with the
3729 history comment character, so they may be preserved across shell ses-
3730 sions. This uses the history comment character to distinguish time-
3731 stamps from other history lines. After saving the history, the history
3732 file is truncated to contain no more than H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bES
\bSI
\bIZ
\bZE
\bE lines. If H
\bHI
\bIS
\bST
\bT-
\b-
3733 F
\bFI
\bIL
\bLE
\bES
\bSI
\bIZ
\bZE
\bE is unset, or set to null, a non-numeric value, or a numeric
3734 value less than zero, the history file is not truncated.
3736 The builtin command f
\bfc
\bc (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below) may be used
3737 to list or edit and re-execute a portion of the history list. The h
\bhi
\bis
\bs-
\b-
3738 t
\bto
\bor
\bry
\by builtin may be used to display or modify the history list and
3739 manipulate the history file. When using command-line editing, search
3740 commands are available in each editing mode that provide access to the
3743 The shell allows control over which commands are saved on the history
3744 list. The H
\bHI
\bIS
\bST
\bTC
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL and H
\bHI
\bIS
\bST
\bTI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE variables may be set to cause the
3745 shell to save only a subset of the commands entered. The c
\bcm
\bmd
\bdh
\bhi
\bis
\bst
\bt shell
3746 option, if enabled, causes the shell to attempt to save each line of a
3747 multi-line command in the same history entry, adding semicolons where
3748 necessary to preserve syntactic correctness. The l
\bli
\bit
\bth
\bhi
\bis
\bst
\bt shell option
3749 causes the shell to save the command with embedded newlines instead of
3750 semicolons. See the description of the s
\bsh
\bho
\bop
\bpt
\bt builtin below under S
\bSH
\bHE
\bEL
\bLL
\bL
3751 B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS for information on setting and unsetting shell
3754 H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY E
\bEX
\bXP
\bPA
\bAN
\bNS
\bSI
\bIO
\bON
\bN
3755 The shell supports a history expansion feature that is similar to the
3756 history expansion in c
\bcs
\bsh
\bh.
\b. This section describes what syntax features
3757 are available. This feature is enabled by default for interactive
3758 shells, and can be disabled using the +
\b+H
\bH option to the s
\bse
\bet
\bt builtin com-
3759 mand (see S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS below). Non-interactive shells do not
3760 perform history expansion by default.
3762 History expansions introduce words from the history list into the input
3763 stream, making it easy to repeat commands, insert the arguments to a
3764 previous command into the current input line, or fix errors in previous
3767 History expansion is performed immediately after a complete line is
3768 read, before the shell breaks it into words. It takes place in two
3769 parts. The first is to determine which line from the history list to
3770 use during substitution. The second is to select portions of that line
3771 for inclusion into the current one. The line selected from the history
3772 is the _
\be_
\bv_
\be_
\bn_
\bt, and the portions of that line that are acted upon are
3773 _
\bw_
\bo_
\br_
\bd_
\bs. Various _
\bm_
\bo_
\bd_
\bi_
\bf_
\bi_
\be_
\br_
\bs are available to manipulate the selected
3774 words. The line is broken into words in the same fashion as when read-
3775 ing input, so that several _
\bm_
\be_
\bt_
\ba_
\bc_
\bh_
\ba_
\br_
\ba_
\bc_
\bt_
\be_
\br-separated words surrounded by
3776 quotes are considered one word. History expansions are introduced by
3777 the appearance of the history expansion character, which is !
\b! by
3778 default. Only backslash (\
\b\) and single quotes can quote the history
3779 expansion character.
3781 Several characters inhibit history expansion if found immediately fol-
3782 lowing the history expansion character, even if it is unquoted: space,
3783 tab, newline, carriage return, and =
\b=. If the e
\bex
\bxt
\btg
\bgl
\blo
\bob
\bb shell option is
3784 enabled, (
\b( will also inhibit expansion.
3786 Several shell options settable with the s
\bsh
\bho
\bop
\bpt
\bt builtin may be used to
3787 tailor the behavior of history expansion. If the h
\bhi
\bis
\bst
\btv
\bve
\ber
\bri
\bif
\bfy
\by shell
3788 option is enabled (see the description of the s
\bsh
\bho
\bop
\bpt
\bt builtin below), and
3789 r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used, history substitutions are not immediately
3790 passed to the shell parser. Instead, the expanded line is reloaded
3791 into the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be editing buffer for further modification. If r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be
3792 is being used, and the h
\bhi
\bis
\bst
\btr
\bre
\bee
\bed
\bdi
\bit
\bt shell option is enabled, a failed
3793 history substitution will be reloaded into the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be editing buffer
3794 for correction. The -
\b-p
\bp option to the h
\bhi
\bis
\bst
\bto
\bor
\bry
\by builtin command may be
3795 used to see what a history expansion will do before using it. The -
\b-s
\bs
3796 option to the h
\bhi
\bis
\bst
\bto
\bor
\bry
\by builtin may be used to add commands to the end of
3797 the history list without actually executing them, so that they are
3798 available for subsequent recall.
3800 The shell allows control of the various characters used by the history
3801 expansion mechanism (see the description of h
\bhi
\bis
\bst
\btc
\bch
\bha
\bar
\brs
\bs above under S
\bSh
\bhe
\bel
\bll
\bl
3802 V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs). The shell uses the history comment character to mark his-
3803 tory timestamps when writing the history file.
3805 E
\bEv
\bve
\ben
\bnt
\bt D
\bDe
\bes
\bsi
\big
\bgn
\bna
\bat
\bto
\bor
\brs
\bs
3806 An event designator is a reference to a command line entry in the his-
3807 tory list. Unless the reference is absolute, events are relative to
3808 the current position in the history list.
3810 !
\b! Start a history substitution, except when followed by a b
\bbl
\bla
\ban
\bnk
\bk,
3811 newline, carriage return, = or ( (when the e
\bex
\bxt
\btg
\bgl
\blo
\bob
\bb shell option
3812 is enabled using the s
\bsh
\bho
\bop
\bpt
\bt builtin).
3813 !
\b!_
\bn Refer to command line _
\bn.
3814 !
\b!-
\b-_
\bn Refer to the current command minus _
\bn.
3815 !
\b!!
\b! Refer to the previous command. This is a synonym for `!-1'.
3816 !
\b!_
\bs_
\bt_
\br_
\bi_
\bn_
\bg
3817 Refer to the most recent command preceding the current position
3818 in the history list starting with _
\bs_
\bt_
\br_
\bi_
\bn_
\bg.
3819 !
\b!?
\b?_
\bs_
\bt_
\br_
\bi_
\bn_
\bg[
\b[?
\b?]
\b]
3820 Refer to the most recent command preceding the current position
3821 in the history list containing _
\bs_
\bt_
\br_
\bi_
\bn_
\bg. The trailing ?
\b? may be
3822 omitted if _
\bs_
\bt_
\br_
\bi_
\bn_
\bg is followed immediately by a newline.
3823 ^
\b^_
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1^
\b^_
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2^
\b^
3824 Quick substitution. Repeat the previous command, replacing
3825 _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1 with _
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2. Equivalent to ``!!:s/_
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b1/_
\bs_
\bt_
\br_
\bi_
\bn_
\bg_
\b2/''
3826 (see M
\bMo
\bod
\bdi
\bif
\bfi
\bie
\ber
\brs
\bs below).
3827 !
\b!#
\b# The entire command line typed so far.
3829 W
\bWo
\bor
\brd
\bd D
\bDe
\bes
\bsi
\big
\bgn
\bna
\bat
\bto
\bor
\brs
\bs
3830 Word designators are used to select desired words from the event. A :
\b:
3831 separates the event specification from the word designator. It may be
3832 omitted if the word designator begins with a ^
\b^, $
\b$, *
\b*, -
\b-, or %
\b%. Words
3833 are numbered from the beginning of the line, with the first word being
3834 denoted by 0 (zero). Words are inserted into the current line sepa-
3835 rated by single spaces.
3837 0
\b0 (
\b(z
\bze
\ber
\bro
\bo)
\b)
3838 The zeroth word. For the shell, this is the command word.
3839 _
\bn The _
\bnth word.
3840 ^
\b^ The first argument. That is, word 1.
3841 $
\b$ The last word. This is usually the last argument, but will
3842 expand to the zeroth word if there is only one word in the line.
3843 %
\b% The word matched by the most recent `?_
\bs_
\bt_
\br_
\bi_
\bn_
\bg?' search.
3844 _
\bx-
\b-_
\by A range of words; `-_
\by' abbreviates `0-_
\by'.
3845 *
\b* All of the words but the zeroth. This is a synonym for `_
\b1_
\b-_
\b$'.
3846 It is not an error to use *
\b* if there is just one word in the
3847 event; the empty string is returned in that case.
3848 x
\bx*
\b* Abbreviates _
\bx_
\b-_
\b$.
3849 x
\bx-
\b- Abbreviates _
\bx_
\b-_
\b$ like x
\bx*
\b*, but omits the last word.
3851 If a word designator is supplied without an event specification, the
3852 previous command is used as the event.
3854 M
\bMo
\bod
\bdi
\bif
\bfi
\bie
\ber
\brs
\bs
3855 After the optional word designator, there may appear a sequence of one
3856 or more of the following modifiers, each preceded by a `:'.
3858 h
\bh Remove a trailing filename component, leaving only the head.
3859 t
\bt Remove all leading filename components, leaving the tail.
3860 r
\br Remove a trailing suffix of the form _
\b._
\bx_
\bx_
\bx, leaving the basename.
3861 e
\be Remove all but the trailing suffix.
3862 p
\bp Print the new command but do not execute it.
3863 q
\bq Quote the substituted words, escaping further substitutions.
3864 x
\bx Quote the substituted words as with q
\bq, but break into words at
3865 b
\bbl
\bla
\ban
\bnk
\bks
\bs and newlines.
3866 s
\bs/
\b/_
\bo_
\bl_
\bd/
\b/_
\bn_
\be_
\bw/
\b/
3867 Substitute _
\bn_
\be_
\bw for the first occurrence of _
\bo_
\bl_
\bd in the event
3868 line. Any delimiter can be used in place of /. The final
3869 delimiter is optional if it is the last character of the event
3870 line. The delimiter may be quoted in _
\bo_
\bl_
\bd and _
\bn_
\be_
\bw with a single
3871 backslash. If & appears in _
\bn_
\be_
\bw, it is replaced by _
\bo_
\bl_
\bd. A sin-
3872 gle backslash will quote the &. If _
\bo_
\bl_
\bd is null, it is set to
3873 the last _
\bo_
\bl_
\bd substituted, or, if no previous history substitu-
3874 tions took place, the last _
\bs_
\bt_
\br_
\bi_
\bn_
\bg in a !
\b!?
\b?_
\bs_
\bt_
\br_
\bi_
\bn_
\bg[
\b[?
\b?]
\b] search.
3875 &
\b& Repeat the previous substitution.
3876 g
\bg Cause changes to be applied over the entire event line. This is
3877 used in conjunction with `:
\b:s
\bs' (e.g., `:
\b:g
\bgs
\bs/
\b/_
\bo_
\bl_
\bd/
\b/_
\bn_
\be_
\bw/
\b/') or `:
\b:&
\b&'.
3878 If used with `:
\b:s
\bs', any delimiter can be used in place of /, and
3879 the final delimiter is optional if it is the last character of
3880 the event line. An a
\ba may be used as a synonym for g
\bg.
3881 G
\bG Apply the following `s
\bs' modifier once to each word in the event
3884 S
\bSH
\bHE
\bEL
\bLL
\bL B
\bBU
\bUI
\bIL
\bLT
\bTI
\bIN
\bN C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bDS
\bS
3885 Unless otherwise noted, each builtin command documented in this section
3886 as accepting options preceded by -
\b- accepts -
\b--
\b- to signify the end of the
3887 options. The :
\b:, t
\btr
\bru
\bue
\be, f
\bfa
\bal
\bls
\bse
\be, and t
\bte
\bes
\bst
\bt builtins do not accept options
3888 and do not treat -
\b--
\b- specially. The e
\bex
\bxi
\bit
\bt, l
\blo
\bog
\bgo
\bou
\but
\bt, b
\bbr
\bre
\bea
\bak
\bk, c
\bco
\bon
\bnt
\bti
\bin
\bnu
\bue
\be, l
\ble
\bet
\bt,
3889 and s
\bsh
\bhi
\bif
\bft
\bt builtins accept and process arguments beginning with -
\b- with-
3890 out requiring -
\b--
\b-. Other builtins that accept arguments but are not
3891 specified as accepting options interpret arguments beginning with -
\b- as
3892 invalid options and require -
\b--
\b- to prevent this interpretation.
3893 :
\b: [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
3894 No effect; the command does nothing beyond expanding _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs
3895 and performing any specified redirections. A zero exit code is
3898 .
\b. _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
3899 s
\bso
\bou
\bur
\brc
\bce
\be _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
3900 Read and execute commands from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be in the current shell
3901 environment and return the exit status of the last command exe-
3902 cuted from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be. If _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be does not contain a slash,
3903 filenames in P
\bPA
\bAT
\bTH
\bH are used to find the directory containing
3904 _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be. The file searched for in P
\bPA
\bAT
\bTH
\bH need not be executable.
3905 When b
\bba
\bas
\bsh
\bh is not in _
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be, the current directory is
3906 searched if no file is found in P
\bPA
\bAT
\bTH
\bH. If the s
\bso
\bou
\bur
\brc
\bce
\bep
\bpa
\bat
\bth
\bh option
3907 to the s
\bsh
\bho
\bop
\bpt
\bt builtin command is turned off, the P
\bPA
\bAT
\bTH
\bH is not
3908 searched. If any _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs are supplied, they become the posi-
3909 tional parameters when _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be is executed. Otherwise the
3910 positional parameters are unchanged. The return status is the
3911 status of the last command exited within the script (0 if no
3912 commands are executed), and false if _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be is not found or
3915 a
\bal
\bli
\bia
\bas
\bs [-
\b-p
\bp] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
3916 A
\bAl
\bli
\bia
\bas
\bs with no arguments or with the -
\b-p
\bp option prints the list of
3917 aliases in the form a
\bal
\bli
\bia
\bas
\bs _
\bn_
\ba_
\bm_
\be=_
\bv_
\ba_
\bl_
\bu_
\be on standard output. When
3918 arguments are supplied, an alias is defined for each _
\bn_
\ba_
\bm_
\be whose
3919 _
\bv_
\ba_
\bl_
\bu_
\be is given. A trailing space in _
\bv_
\ba_
\bl_
\bu_
\be causes the next word
3920 to be checked for alias substitution when the alias is expanded.
3921 For each _
\bn_
\ba_
\bm_
\be in the argument list for which no _
\bv_
\ba_
\bl_
\bu_
\be is sup-
3922 plied, the name and value of the alias is printed. A
\bAl
\bli
\bia
\bas
\bs
3923 returns true unless a _
\bn_
\ba_
\bm_
\be is given for which no alias has been
3926 b
\bbg
\bg [_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc ...]
3927 Resume each suspended job _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc in the background, as if it
3928 had been started with &
\b&. If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not present, the shell's
3929 notion of the _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb is used. b
\bbg
\bg _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc returns 0 unless
3930 run when job control is disabled or, when run with job control
3931 enabled, any specified _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc was not found or was started
3932 without job control.
3934 b
\bbi
\bin
\bnd
\bd [-
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp] [-
\b-l
\blp
\bps
\bsv
\bvP
\bPS
\bSV
\bVX
\bX]
3935 b
\bbi
\bin
\bnd
\bd [-
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp] [-
\b-q
\bq _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn] [-
\b-u
\bu _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn] [-
\b-r
\br _
\bk_
\be_
\by_
\bs_
\be_
\bq]
3936 b
\bbi
\bin
\bnd
\bd [-
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp] -
\b-f
\bf _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
3937 b
\bbi
\bin
\bnd
\bd [-
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp] -
\b-x
\bx _
\bk_
\be_
\by_
\bs_
\be_
\bq:_
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd
3938 b
\bbi
\bin
\bnd
\bd [-
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp] _
\bk_
\be_
\by_
\bs_
\be_
\bq:_
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be
3939 b
\bbi
\bin
\bnd
\bd _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd
3940 Display current r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be key and function bindings, bind a key
3941 sequence to a r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be function or macro, or set a r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be
3942 variable. Each non-option argument is a command as it would
3943 appear in _
\b._
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc, but each binding or command must be passed
3944 as a separate argument; e.g., '"\C-x\C-r": re-read-init-file'.
3945 Options, if supplied, have the following meanings:
3946 -
\b-m
\bm _
\bk_
\be_
\by_
\bm_
\ba_
\bp
3947 Use _
\bk_
\be_
\by_
\bm_
\ba_
\bp as the keymap to be affected by the subsequent
3948 bindings. Acceptable _
\bk_
\be_
\by_
\bm_
\ba_
\bp names are _
\be_
\bm_
\ba_
\bc_
\bs_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bs_
\bt_
\ba_
\bn_
\b-
3949 _
\bd_
\ba_
\br_
\bd_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bm_
\be_
\bt_
\ba_
\b, _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bc_
\bt_
\bl_
\bx_
\b, _
\bv_
\bi_
\b, _
\bv_
\bi_
\b-_
\bm_
\bo_
\bv_
\be_
\b, _
\bv_
\bi_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd,
3950 and _
\bv_
\bi_
\b-_
\bi_
\bn_
\bs_
\be_
\br_
\bt. _
\bv_
\bi is equivalent to _
\bv_
\bi_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd; _
\be_
\bm_
\ba_
\bc_
\bs is
3951 equivalent to _
\be_
\bm_
\ba_
\bc_
\bs_
\b-_
\bs_
\bt_
\ba_
\bn_
\bd_
\ba_
\br_
\bd.
3952 -
\b-l
\bl List the names of all r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be functions.
3953 -
\b-p
\bp Display r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be function names and bindings in such a
3954 way that they can be re-read.
3955 -
\b-P
\bP List current r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be function names and bindings.
3956 -
\b-s
\bs Display r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be key sequences bound to macros and the
3957 strings they output in such a way that they can be re-
3959 -
\b-S
\bS Display r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be key sequences bound to macros and the
3960 strings they output.
3961 -
\b-v
\bv Display r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be variable names and values in such a way
3962 that they can be re-read.
3963 -
\b-V
\bV List current r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be variable names and values.
3964 -
\b-f
\bf _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
3965 Read key bindings from _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be.
3966 -
\b-q
\bq _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn
3967 Query about which keys invoke the named _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn.
3968 -
\b-u
\bu _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn
3969 Unbind all keys bound to the named _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn.
3970 -
\b-r
\br _
\bk_
\be_
\by_
\bs_
\be_
\bq
3971 Remove any current binding for _
\bk_
\be_
\by_
\bs_
\be_
\bq.
3972 -
\b-x
\bx _
\bk_
\be_
\by_
\bs_
\be_
\bq:
\b:_
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd
3973 Cause _
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd to be executed whenever _
\bk_
\be_
\by_
\bs_
\be_
\bq is
3974 entered. When _
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is executed, the shell sets
3975 the R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE_
\b_L
\bLI
\bIN
\bNE
\bE variable to the contents of the r
\bre
\bea
\bad
\bd-
\b-
3976 l
\bli
\bin
\bne
\be line buffer and the R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE_
\b_P
\bPO
\bOI
\bIN
\bNT
\bT variable to the
3977 current location of the insertion point. If the executed
3978 command changes the value of R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE_
\b_L
\bLI
\bIN
\bNE
\bE or R
\bRE
\bEA
\bAD
\bD-
\b-
3979 L
\bLI
\bIN
\bNE
\bE_
\b_P
\bPO
\bOI
\bIN
\bNT
\bT, those new values will be reflected in the
3981 -
\b-X
\bX List all key sequences bound to shell commands and the
3982 associated commands in a format that can be reused as
3985 The return value is 0 unless an unrecognized option is given or
3988 b
\bbr
\bre
\bea
\bak
\bk [_
\bn]
3989 Exit from within a f
\bfo
\bor
\br, w
\bwh
\bhi
\bil
\ble
\be, u
\bun
\bnt
\bti
\bil
\bl, or s
\bse
\bel
\ble
\bec
\bct
\bt loop. If _
\bn is
3990 specified, break _
\bn levels. _
\bn must be >= 1. If _
\bn is greater
3991 than the number of enclosing loops, all enclosing loops are
3992 exited. The return value is 0 unless _
\bn is not greater than or
3995 b
\bbu
\bui
\bil
\blt
\bti
\bin
\bn _
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
3996 Execute the specified shell builtin, passing it _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs, and
3997 return its exit status. This is useful when defining a function
3998 whose name is the same as a shell builtin, retaining the func-
3999 tionality of the builtin within the function. The c
\bcd
\bd builtin is
4000 commonly redefined this way. The return status is false if
4001 _
\bs_
\bh_
\be_
\bl_
\bl_
\b-_
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn is not a shell builtin command.
4003 c
\bca
\bal
\bll
\ble
\ber
\br [_
\be_
\bx_
\bp_
\br]
4004 Returns the context of any active subroutine call (a shell func-
4005 tion or a script executed with the .
\b. or s
\bso
\bou
\bur
\brc
\bce
\be builtins). With-
4006 out _
\be_
\bx_
\bp_
\br, c
\bca
\bal
\bll
\ble
\ber
\br displays the line number and source filename of
4007 the current subroutine call. If a non-negative integer is sup-
4008 plied as _
\be_
\bx_
\bp_
\br, c
\bca
\bal
\bll
\ble
\ber
\br displays the line number, subroutine name,
4009 and source file corresponding to that position in the current
4010 execution call stack. This extra information may be used, for
4011 example, to print a stack trace. The current frame is frame 0.
4012 The return value is 0 unless the shell is not executing a sub-
4013 routine call or _
\be_
\bx_
\bp_
\br does not correspond to a valid position in
4016 c
\bcd
\bd [-
\b-L
\bL|[-
\b-P
\bP [-
\b-e
\be]] [-@]] [_
\bd_
\bi_
\br]
4017 Change the current directory to _
\bd_
\bi_
\br. if _
\bd_
\bi_
\br is not supplied,
4018 the value of the H
\bHO
\bOM
\bME
\bE shell variable is the default. Any addi-
4019 tional arguments following _
\bd_
\bi_
\br are ignored. The variable C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH
4020 defines the search path for the directory containing _
\bd_
\bi_
\br: each
4021 directory name in C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH is searched for _
\bd_
\bi_
\br. Alternative
4022 directory names in C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH are separated by a colon (:). A null
4023 directory name in C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH is the same as the current directory,
4024 i.e., ``.
\b.''. If _
\bd_
\bi_
\br begins with a slash (/), then C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH is not
4025 used. The -
\b-P
\bP option causes c
\bcd
\bd to use the physical directory
4026 structure by resolving symbolic links while traversing _
\bd_
\bi_
\br and
4027 before processing instances of _
\b._
\b. in _
\bd_
\bi_
\br (see also the -
\b-P
\bP option
4028 to the s
\bse
\bet
\bt builtin command); the -
\b-L
\bL option forces symbolic links
4029 to be followed by resolving the link after processing instances
4030 of _
\b._
\b. in _
\bd_
\bi_
\br. If _
\b._
\b. appears in _
\bd_
\bi_
\br, it is processed by removing
4031 the immediately previous pathname component from _
\bd_
\bi_
\br, back to a
4032 slash or the beginning of _
\bd_
\bi_
\br. If the -
\b-e
\be option is supplied
4033 with -
\b-P
\bP, and the current working directory cannot be success-
4034 fully determined after a successful directory change, c
\bcd
\bd will
4035 return an unsuccessful status. On systems that support it, the
4036 -
\b-@
\b@ option presents the extended attributes associated with a
4037 file as a directory. An argument of -
\b- is converted to $
\b$O
\bOL
\bLD
\bDP
\bPW
\bWD
\bD
4038 before the directory change is attempted. If a non-empty direc-
4039 tory name from C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH is used, or if -
\b- is the first argument,
4040 and the directory change is successful, the absolute pathname of
4041 the new working directory is written to the standard output.
4042 The return value is true if the directory was successfully
4043 changed; false otherwise.
4045 c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd [-
\b-p
\bpV
\bVv
\bv] _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\ba_
\br_
\bg ...]
4046 Run _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd with _
\ba_
\br_
\bg_
\bs suppressing the normal shell function
4047 lookup. Only builtin commands or commands found in the P
\bPA
\bAT
\bTH
\bH are
4048 executed. If the -
\b-p
\bp option is given, the search for _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is
4049 performed using a default value for P
\bPA
\bAT
\bTH
\bH that is guaranteed to
4050 find all of the standard utilities. If either the -
\b-V
\bV or -
\b-v
\bv
4051 option is supplied, a description of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is printed. The -
\b-v
\bv
4052 option causes a single word indicating the command or filename
4053 used to invoke _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd to be displayed; the -
\b-V
\bV option produces a
4054 more verbose description. If the -
\b-V
\bV or -
\b-v
\bv option is supplied,
4055 the exit status is 0 if _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd was found, and 1 if not. If
4056 neither option is supplied and an error occurred or _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd can-
4057 not be found, the exit status is 127. Otherwise, the exit sta-
4058 tus of the c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd builtin is the exit status of _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd.
4060 c
\bco
\bom
\bmp
\bpg
\bge
\ben
\bn [_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [_
\bw_
\bo_
\br_
\bd]
4061 Generate possible completion matches for _
\bw_
\bo_
\br_
\bd according to the
4062 _
\bo_
\bp_
\bt_
\bi_
\bo_
\bns, which may be any option accepted by the c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be
4063 builtin with the exception of -
\b-p
\bp and -
\b-r
\br, and write the matches
4064 to the standard output. When using the -
\b-F
\bF or -
\b-C
\bC options, the
4065 various shell variables set by the programmable completion
4066 facilities, while available, will not have useful values.
4068 The matches will be generated in the same way as if the pro-
4069 grammable completion code had generated them directly from a
4070 completion specification with the same flags. If _
\bw_
\bo_
\br_
\bd is speci-
4071 fied, only those completions matching _
\bw_
\bo_
\br_
\bd will be displayed.
4073 The return value is true unless an invalid option is supplied,
4074 or no matches were generated.
4076 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be [-
\b-a
\bab
\bbc
\bcd
\bde
\bef
\bfg
\bgj
\bjk
\bks
\bsu
\buv
\bv] [-
\b-o
\bo _
\bc_
\bo_
\bm_
\bp_
\b-_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [-
\b-D
\bDE
\bE] [-
\b-A
\bA _
\ba_
\bc_
\bt_
\bi_
\bo_
\bn] [-
\b-G
\bG _
\bg_
\bl_
\bo_
\bb_
\b-
4077 _
\bp_
\ba_
\bt] [-
\b-W
\bW _
\bw_
\bo_
\br_
\bd_
\bl_
\bi_
\bs_
\bt] [-
\b-F
\bF _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn] [-
\b-C
\bC _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd]
4078 [-
\b-X
\bX _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt] [-
\b-P
\bP _
\bp_
\br_
\be_
\bf_
\bi_
\bx] [-
\b-S
\bS _
\bs_
\bu_
\bf_
\bf_
\bi_
\bx] _
\bn_
\ba_
\bm_
\be [_
\bn_
\ba_
\bm_
\be _
\b._
\b._
\b.]
4079 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be -
\b-p
\bpr
\br [-
\b-D
\bDE
\bE] [_
\bn_
\ba_
\bm_
\be ...]
4080 Specify how arguments to each _
\bn_
\ba_
\bm_
\be should be completed. If the
4081 -
\b-p
\bp option is supplied, or if no options are supplied, existing
4082 completion specifications are printed in a way that allows them
4083 to be reused as input. The -
\b-r
\br option removes a completion spec-
4084 ification for each _
\bn_
\ba_
\bm_
\be, or, if no _
\bn_
\ba_
\bm_
\bes are supplied, all com-
4085 pletion specifications. The -
\b-D
\bD option indicates that the
4086 remaining options and actions should apply to the ``default''
4087 command completion; that is, completion attempted on a command
4088 for which no completion has previously been defined. The -
\b-E
\bE
4089 option indicates that the remaining options and actions should
4090 apply to ``empty'' command completion; that is, completion
4091 attempted on a blank line.
4093 The process of applying these completion specifications when
4094 word completion is attempted is described above under P
\bPr
\bro
\bo-
\b-
4095 g
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn.
4097 Other options, if specified, have the following meanings. The
4098 arguments to the -
\b-G
\bG, -
\b-W
\bW, and -
\b-X
\bX options (and, if necessary, the
4099 -
\b-P
\bP and -
\b-S
\bS options) should be quoted to protect them from expan-
4100 sion before the c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be builtin is invoked.
4101 -
\b-o
\bo _
\bc_
\bo_
\bm_
\bp_
\b-_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn
4102 The _
\bc_
\bo_
\bm_
\bp_
\b-_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn controls several aspects of the comp-
4103 spec's behavior beyond the simple generation of comple-
4104 tions. _
\bc_
\bo_
\bm_
\bp_
\b-_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn may be one of:
4105 b
\bba
\bas
\bsh
\bhd
\bde
\bef
\bfa
\bau
\bul
\blt
\bt
4106 Perform the rest of the default b
\bba
\bas
\bsh
\bh completions
4107 if the compspec generates no matches.
4108 d
\bde
\bef
\bfa
\bau
\bul
\blt
\bt Use readline's default filename completion if
4109 the compspec generates no matches.
4110 d
\bdi
\bir
\brn
\bna
\bam
\bme
\bes
\bs
4111 Perform directory name completion if the comp-
4112 spec generates no matches.
4113 f
\bfi
\bil
\ble
\ben
\bna
\bam
\bme
\bes
\bs
4114 Tell readline that the compspec generates file-
4115 names, so it can perform any filename-specific
4116 processing (like adding a slash to directory
4117 names, quoting special characters, or suppress-
4118 ing trailing spaces). Intended to be used with
4120 n
\bno
\boq
\bqu
\buo
\bot
\bte
\be Tell readline not to quote the completed words
4121 if they are filenames (quoting filenames is the
4123 n
\bno
\bos
\bsp
\bpa
\bac
\bce
\be Tell readline not to append a space (the
4124 default) to words completed at the end of the
4126 p
\bpl
\blu
\bus
\bsd
\bdi
\bir
\brs
\bs
4127 After any matches defined by the compspec are
4128 generated, directory name completion is
4129 attempted and any matches are added to the
4130 results of the other actions.
4131 -
\b-A
\bA _
\ba_
\bc_
\bt_
\bi_
\bo_
\bn
4132 The _
\ba_
\bc_
\bt_
\bi_
\bo_
\bn may be one of the following to generate a
4133 list of possible completions:
4134 a
\bal
\bli
\bia
\bas
\bs Alias names. May also be specified as -
\b-a
\ba.
4135 a
\bar
\brr
\bra
\bay
\byv
\bva
\bar
\br
4136 Array variable names.
4137 b
\bbi
\bin
\bnd
\bdi
\bin
\bng
\bg R
\bRe
\bea
\bad
\bdl
\bli
\bin
\bne
\be key binding names.
4138 b
\bbu
\bui
\bil
\blt
\bti
\bin
\bn Names of shell builtin commands. May also be
4139 specified as -
\b-b
\bb.
4140 c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd Command names. May also be specified as -
\b-c
\bc.
4141 d
\bdi
\bir
\bre
\bec
\bct
\bto
\bor
\bry
\by
4142 Directory names. May also be specified as -
\b-d
\bd.
4143 d
\bdi
\bis
\bsa
\bab
\bbl
\ble
\bed
\bd
4144 Names of disabled shell builtins.
4145 e
\ben
\bna
\bab
\bbl
\ble
\bed
\bd Names of enabled shell builtins.
4146 e
\bex
\bxp
\bpo
\bor
\brt
\bt Names of exported shell variables. May also be
4147 specified as -
\b-e
\be.
4148 f
\bfi
\bil
\ble
\be File names. May also be specified as -
\b-f
\bf.
4149 f
\bfu
\bun
\bnc
\bct
\bti
\bio
\bon
\bn
4150 Names of shell functions.
4151 g
\bgr
\bro
\bou
\bup
\bp Group names. May also be specified as -
\b-g
\bg.
4152 h
\bhe
\bel
\blp
\bpt
\bto
\bop
\bpi
\bic
\bc
4153 Help topics as accepted by the h
\bhe
\bel
\blp
\bp builtin.
4154 h
\bho
\bos
\bst
\btn
\bna
\bam
\bme
\be
4155 Hostnames, as taken from the file specified by
4156 the H
\bHO
\bOS
\bST
\bTF
\bFI
\bIL
\bLE
\bE shell variable.
4157 j
\bjo
\bob
\bb Job names, if job control is active. May also
4158 be specified as -
\b-j
\bj.
4159 k
\bke
\bey
\byw
\bwo
\bor
\brd
\bd Shell reserved words. May also be specified as
4161 r
\bru
\bun
\bnn
\bni
\bin
\bng
\bg Names of running jobs, if job control is active.
4162 s
\bse
\ber
\brv
\bvi
\bic
\bce
\be Service names. May also be specified as -
\b-s
\bs.
4163 s
\bse
\bet
\bto
\bop
\bpt
\bt Valid arguments for the -
\b-o
\bo option to the s
\bse
\bet
\bt
4165 s
\bsh
\bho
\bop
\bpt
\bt Shell option names as accepted by the s
\bsh
\bho
\bop
\bpt
\bt
4167 s
\bsi
\big
\bgn
\bna
\bal
\bl Signal names.
4168 s
\bst
\bto
\bop
\bpp
\bpe
\bed
\bd Names of stopped jobs, if job control is active.
4169 u
\bus
\bse
\ber
\br User names. May also be specified as -
\b-u
\bu.
4170 v
\bva
\bar
\bri
\bia
\bab
\bbl
\ble
\be
4171 Names of all shell variables. May also be spec-
4173 -
\b-C
\bC _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd
4174 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is executed in a subshell environment, and its
4175 output is used as the possible completions.
4176 -
\b-F
\bF _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn
4177 The shell function _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn is executed in the current
4178 shell environment. When the function is executed, the
4179 first argument ($
\b$1
\b1) is the name of the command whose
4180 arguments are being completed, the second argument ($
\b$2
\b2)
4181 is the word being completed, and the third argument ($
\b$3
\b3)
4182 is the word preceding the word being completed on the
4183 current command line. When it finishes, the possible
4184 completions are retrieved from the value of the C
\bCO
\bOM
\bMP
\bPR
\bRE
\bE-
\b-
4185 P
\bPL
\bLY
\bY array variable.
4186 -
\b-G
\bG _
\bg_
\bl_
\bo_
\bb_
\bp_
\ba_
\bt
4187 The pathname expansion pattern _
\bg_
\bl_
\bo_
\bb_
\bp_
\ba_
\bt is expanded to
4188 generate the possible completions.
4189 -
\b-P
\bP _
\bp_
\br_
\be_
\bf_
\bi_
\bx
4190 _
\bp_
\br_
\be_
\bf_
\bi_
\bx is added at the beginning of each possible com-
4191 pletion after all other options have been applied.
4192 -
\b-S
\bS _
\bs_
\bu_
\bf_
\bf_
\bi_
\bx
4193 _
\bs_
\bu_
\bf_
\bf_
\bi_
\bx is appended to each possible completion after all
4194 other options have been applied.
4195 -
\b-W
\bW _
\bw_
\bo_
\br_
\bd_
\bl_
\bi_
\bs_
\bt
4196 The _
\bw_
\bo_
\br_
\bd_
\bl_
\bi_
\bs_
\bt is split using the characters in the I
\bIF
\bFS
\bS
4197 special variable as delimiters, and each resultant word
4198 is expanded. The possible completions are the members
4199 of the resultant list which match the word being com-
4201 -
\b-X
\bX _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt
4202 _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt is a pattern as used for pathname expansion.
4203 It is applied to the list of possible completions gener-
4204 ated by the preceding options and arguments, and each
4205 completion matching _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt is removed from the list.
4206 A leading !
\b! in _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt negates the pattern; in this
4207 case, any completion not matching _
\bf_
\bi_
\bl_
\bt_
\be_
\br_
\bp_
\ba_
\bt is removed.
4209 The return value is true unless an invalid option is supplied,
4210 an option other than -
\b-p
\bp or -
\b-r
\br is supplied without a _
\bn_
\ba_
\bm_
\be argu-
4211 ment, an attempt is made to remove a completion specification
4212 for a _
\bn_
\ba_
\bm_
\be for which no specification exists, or an error occurs
4213 adding a completion specification.
4215 c
\bco
\bom
\bmp
\bpo
\bop
\bpt
\bt [-
\b-o
\bo _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [-
\b-D
\bDE
\bE] [+
\b+o
\bo _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [_
\bn_
\ba_
\bm_
\be]
4216 Modify completion options for each _
\bn_
\ba_
\bm_
\be according to the
4217 _
\bo_
\bp_
\bt_
\bi_
\bo_
\bns, or for the currently-executing completion if no _
\bn_
\ba_
\bm_
\bes
4218 are supplied. If no _
\bo_
\bp_
\bt_
\bi_
\bo_
\bns are given, display the completion
4219 options for each _
\bn_
\ba_
\bm_
\be or the current completion. The possible
4220 values of _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn are those valid for the c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be builtin
4221 described above. The -
\b-D
\bD option indicates that the remaining
4222 options should apply to the ``default'' command completion; that
4223 is, completion attempted on a command for which no completion
4224 has previously been defined. The -
\b-E
\bE option indicates that the
4225 remaining options should apply to ``empty'' command completion;
4226 that is, completion attempted on a blank line.
4228 The return value is true unless an invalid option is supplied,
4229 an attempt is made to modify the options for a _
\bn_
\ba_
\bm_
\be for which no
4230 completion specification exists, or an output error occurs.
4232 c
\bco
\bon
\bnt
\bti
\bin
\bnu
\bue
\be [_
\bn]
4233 Resume the next iteration of the enclosing f
\bfo
\bor
\br, w
\bwh
\bhi
\bil
\ble
\be, u
\bun
\bnt
\bti
\bil
\bl, or
4234 s
\bse
\bel
\ble
\bec
\bct
\bt loop. If _
\bn is specified, resume at the _
\bnth enclosing
4235 loop. _
\bn must be >= 1. If _
\bn is greater than the number of
4236 enclosing loops, the last enclosing loop (the ``top-level''
4237 loop) is resumed. The return value is 0 unless _
\bn is not greater
4240 d
\bde
\bec
\bcl
\bla
\bar
\bre
\be [-
\b-a
\baA
\bAf
\bfF
\bFg
\bgi
\bil
\bln
\bnr
\brt
\btu
\bux
\bx] [-
\b-p
\bp] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
4241 t
\bty
\byp
\bpe
\bes
\bse
\bet
\bt [-
\b-a
\baA
\bAf
\bfF
\bFg
\bgi
\bil
\bln
\bnr
\brt
\btu
\bux
\bx] [-
\b-p
\bp] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
4242 Declare variables and/or give them attributes. If no _
\bn_
\ba_
\bm_
\bes are
4243 given then display the values of variables. The -
\b-p
\bp option will
4244 display the attributes and values of each _
\bn_
\ba_
\bm_
\be. When -
\b-p
\bp is used
4245 with _
\bn_
\ba_
\bm_
\be arguments, additional options, other than -
\b-f
\bf and -
\b-F
\bF,
4246 are ignored. When -
\b-p
\bp is supplied without _
\bn_
\ba_
\bm_
\be arguments, it
4247 will display the attributes and values of all variables having
4248 the attributes specified by the additional options. If no other
4249 options are supplied with -
\b-p
\bp, d
\bde
\bec
\bcl
\bla
\bar
\bre
\be will display the
4250 attributes and values of all shell variables. The -
\b-f
\bf option
4251 will restrict the display to shell functions. The -
\b-F
\bF option
4252 inhibits the display of function definitions; only the function
4253 name and attributes are printed. If the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg shell option
4254 is enabled using s
\bsh
\bho
\bop
\bpt
\bt, the source file name and line number
4255 where the function is defined are displayed as well. The -
\b-F
\bF
4256 option implies -
\b-f
\bf. The -
\b-g
\bg option forces variables to be created
4257 or modified at the global scope, even when d
\bde
\bec
\bcl
\bla
\bar
\bre
\be is executed
4258 in a shell function. It is ignored in all other cases. The
4259 following options can be used to restrict output to variables
4260 with the specified attribute or to give variables attributes:
4261 -
\b-a
\ba Each _
\bn_
\ba_
\bm_
\be is an indexed array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs
4263 -
\b-A
\bA Each _
\bn_
\ba_
\bm_
\be is an associative array variable (see A
\bAr
\brr
\bra
\bay
\bys
\bs
4265 -
\b-f
\bf Use function names only.
4266 -
\b-i
\bi The variable is treated as an integer; arithmetic evalua-
4267 tion (see A
\bAR
\bRI
\bIT
\bTH
\bHM
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN above) is performed when
4268 the variable is assigned a value.
4269 -
\b-l
\bl When the variable is assigned a value, all upper-case
4270 characters are converted to lower-case. The upper-case
4271 attribute is disabled.
4272 -
\b-n
\bn Give each _
\bn_
\ba_
\bm_
\be the _
\bn_
\ba_
\bm_
\be_
\br_
\be_
\bf attribute, making it a name
4273 reference to another variable. That other variable is
4274 defined by the value of _
\bn_
\ba_
\bm_
\be. All references and assign-
4275 ments to _
\bn_
\ba_
\bm_
\be, except for changing the -
\b-n
\bn attribute
4276 itself, are performed on the variable referenced by
4277 _
\bn_
\ba_
\bm_
\be's value. The -
\b-n
\bn attribute cannot be applied to
4279 -
\b-r
\br Make _
\bn_
\ba_
\bm_
\bes readonly. These names cannot then be assigned
4280 values by subsequent assignment statements or unset.
4281 -
\b-t
\bt Give each _
\bn_
\ba_
\bm_
\be the _
\bt_
\br_
\ba_
\bc_
\be attribute. Traced functions
4282 inherit the D
\bDE
\bEB
\bBU
\bUG
\bG and R
\bRE
\bET
\bTU
\bUR
\bRN
\bN traps from the calling
4283 shell. The trace attribute has no special meaning for
4285 -
\b-u
\bu When the variable is assigned a value, all lower-case
4286 characters are converted to upper-case. The lower-case
4287 attribute is disabled.
4288 -
\b-x
\bx Mark _
\bn_
\ba_
\bm_
\bes for export to subsequent commands via the
4291 Using `+' instead of `-' turns off the attribute instead, with
4292 the exceptions that +
\b+a
\ba may not be used to destroy an array vari-
4293 able and +
\b+r
\br will not remove the readonly attribute. When used
4294 in a function, d
\bde
\bec
\bcl
\bla
\bar
\bre
\be and t
\bty
\byp
\bpe
\bes
\bse
\bet
\bt make each _
\bn_
\ba_
\bm_
\be local, as with
4295 the l
\blo
\boc
\bca
\bal
\bl command, unless the -
\b-g
\bg option is supplied. If a vari-
4296 able name is followed by =_
\bv_
\ba_
\bl_
\bu_
\be, the value of the variable is
4297 set to _
\bv_
\ba_
\bl_
\bu_
\be. When using -
\b-a
\ba or -
\b-A
\bA and the compound assignment
4298 syntax to create array variables, additional attributes do not
4299 take effect until subsequent assignments. The return value is 0
4300 unless an invalid option is encountered, an attempt is made to
4301 define a function using ``-f foo=bar'', an attempt is made to
4302 assign a value to a readonly variable, an attempt is made to
4303 assign a value to an array variable without using the compound
4304 assignment syntax (see A
\bAr
\brr
\bra
\bay
\bys
\bs above), one of the _
\bn_
\ba_
\bm_
\be_
\bs is not a
4305 valid shell variable name, an attempt is made to turn off read-
4306 only status for a readonly variable, an attempt is made to turn
4307 off array status for an array variable, or an attempt is made to
4308 display a non-existent function with -
\b-f
\bf.
4310 d
\bdi
\bir
\brs
\bs [
\b[-
\b-c
\bcl
\blp
\bpv
\bv]
\b] [
\b[+
\b+_
\bn]
\b] [
\b[-
\b-_
\bn]
\b]
4311 Without options, displays the list of currently remembered
4312 directories. The default display is on a single line with
4313 directory names separated by spaces. Directories are added to
4314 the list with the p
\bpu
\bus
\bsh
\bhd
\bd command; the p
\bpo
\bop
\bpd
\bd command removes
4315 entries from the list.
4316 -
\b-c
\bc Clears the directory stack by deleting all of the
4318 -
\b-l
\bl Produces a listing using full pathnames; the default
4319 listing format uses a tilde to denote the home directory.
4320 -
\b-p
\bp Print the directory stack with one entry per line.
4321 -
\b-v
\bv Print the directory stack with one entry per line, pre-
4322 fixing each entry with its index in the stack.
4323 +
\b+_
\bn Displays the _
\bnth entry counting from the left of the list
4324 shown by d
\bdi
\bir
\brs
\bs when invoked without options, starting with
4326 -
\b-_
\bn Displays the _
\bnth entry counting from the right of the
4327 list shown by d
\bdi
\bir
\brs
\bs when invoked without options, starting
4330 The return value is 0 unless an invalid option is supplied or _
\bn
4331 indexes beyond the end of the directory stack.
4333 d
\bdi
\bis
\bso
\bow
\bwn
\bn [-
\b-a
\bar
\br] [-
\b-h
\bh] [_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc ...]
4334 Without options, remove each _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc from the table of active
4335 jobs. If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not present, and neither the -
\b-a
\ba nor the -
\b-r
\br
4336 option is supplied, the _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb is used. If the -
\b-h
\bh option
4337 is given, each _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not removed from the table, but is
4338 marked so that S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP is not sent to the job if the shell
4339 receives a S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP. If no _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is supplied, the -
\b-a
\ba option
4340 means to remove or mark all jobs; the -
\b-r
\br option without a _
\bj_
\bo_
\bb_
\b-
4341 _
\bs_
\bp_
\be_
\bc argument restricts operation to running jobs. The return
4342 value is 0 unless a _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc does not specify a valid job.
4344 e
\bec
\bch
\bho
\bo [-
\b-n
\bne
\beE
\bE] [_
\ba_
\br_
\bg ...]
4345 Output the _
\ba_
\br_
\bgs, separated by spaces, followed by a newline.
4346 The return status is 0 unless a write error occurs. If -
\b-n
\bn is
4347 specified, the trailing newline is suppressed. If the -
\b-e
\be option
4348 is given, interpretation of the following backslash-escaped
4349 characters is enabled. The -
\b-E
\bE option disables the interpreta-
4350 tion of these escape characters, even on systems where they are
4351 interpreted by default. The x
\bxp
\bpg
\bg_
\b_e
\bec
\bch
\bho
\bo shell option may be used
4352 to dynamically determine whether or not e
\bec
\bch
\bho
\bo expands these
4353 escape characters by default. e
\bec
\bch
\bho
\bo does not interpret -
\b--
\b- to
4354 mean the end of options. e
\bec
\bch
\bho
\bo interprets the following escape
4356 \
\b\a
\ba alert (bell)
4358 \
\b\c
\bc suppress further output
4360 \
\b\E
\bE an escape character
4363 \
\b\r
\br carriage return
4364 \
\b\t
\bt horizontal tab
4365 \
\b\v
\bv vertical tab
4367 \
\b\0
\b0_
\bn_
\bn_
\bn the eight-bit character whose value is the octal value
4368 _
\bn_
\bn_
\bn (zero to three octal digits)
4369 \
\b\x
\bx_
\bH_
\bH the eight-bit character whose value is the hexadecimal
4370 value _
\bH_
\bH (one or two hex digits)
4371 \
\b\u
\bu_
\bH_
\bH_
\bH_
\bH the Unicode (ISO/IEC 10646) character whose value is the
4372 hexadecimal value _
\bH_
\bH_
\bH_
\bH (one to four hex digits)
4373 \
\b\U
\bU_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH
4374 the Unicode (ISO/IEC 10646) character whose value is the
4375 hexadecimal value _
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH_
\bH (one to eight hex digits)
4377 e
\ben
\bna
\bab
\bbl
\ble
\be [-
\b-a
\ba] [-
\b-d
\bdn
\bnp
\bps
\bs] [-
\b-f
\bf _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be] [_
\bn_
\ba_
\bm_
\be ...]
4378 Enable and disable builtin shell commands. Disabling a builtin
4379 allows a disk command which has the same name as a shell builtin
4380 to be executed without specifying a full pathname, even though
4381 the shell normally searches for builtins before disk commands.
4382 If -
\b-n
\bn is used, each _
\bn_
\ba_
\bm_
\be is disabled; otherwise, _
\bn_
\ba_
\bm_
\be_
\bs are
4383 enabled. For example, to use the t
\bte
\bes
\bst
\bt binary found via the P
\bPA
\bAT
\bTH
\bH
4384 instead of the shell builtin version, run ``enable -n test''.
4385 The -
\b-f
\bf option means to load the new builtin command _
\bn_
\ba_
\bm_
\be from
4386 shared object _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be, on systems that support dynamic loading.
4387 The -
\b-d
\bd option will delete a builtin previously loaded with -
\b-f
\bf.
4388 If no _
\bn_
\ba_
\bm_
\be arguments are given, or if the -
\b-p
\bp option is supplied,
4389 a list of shell builtins is printed. With no other option argu-
4390 ments, the list consists of all enabled shell builtins. If -
\b-n
\bn
4391 is supplied, only disabled builtins are printed. If -
\b-a
\ba is sup-
4392 plied, the list printed includes all builtins, with an indica-
4393 tion of whether or not each is enabled. If -
\b-s
\bs is supplied, the
4394 output is restricted to the POSIX _
\bs_
\bp_
\be_
\bc_
\bi_
\ba_
\bl builtins. The return
4395 value is 0 unless a _
\bn_
\ba_
\bm_
\be is not a shell builtin or there is an
4396 error loading a new builtin from a shared object.
4398 e
\bev
\bva
\bal
\bl [_
\ba_
\br_
\bg ...]
4399 The _
\ba_
\br_
\bgs are read and concatenated together into a single com-
4400 mand. This command is then read and executed by the shell, and
4401 its exit status is returned as the value of e
\bev
\bva
\bal
\bl. If there are
4402 no _
\ba_
\br_
\bg_
\bs, or only null arguments, e
\bev
\bva
\bal
\bl returns 0.
4404 e
\bex
\bxe
\bec
\bc [-
\b-c
\bcl
\bl] [-
\b-a
\ba _
\bn_
\ba_
\bm_
\be] [_
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]]
4405 If _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is specified, it replaces the shell. No new process
4406 is created. The _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs become the arguments to _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd. If
4407 the -
\b-l
\bl option is supplied, the shell places a dash at the begin-
4408 ning of the zeroth argument passed to _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd. This is what
4409 _
\bl_
\bo_
\bg_
\bi_
\bn(1) does. The -
\b-c
\bc option causes _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd to be executed with
4410 an empty environment. If -
\b-a
\ba is supplied, the shell passes _
\bn_
\ba_
\bm_
\be
4411 as the zeroth argument to the executed command. If _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd can-
4412 not be executed for some reason, a non-interactive shell exits,
4413 unless the e
\bex
\bxe
\bec
\bcf
\bfa
\bai
\bil
\bl shell option is enabled. In that case, it
4414 returns failure. An interactive shell returns failure if the
4415 file cannot be executed. If _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is not specified, any redi-
4416 rections take effect in the current shell, and the return status
4417 is 0. If there is a redirection error, the return status is 1.
4419 e
\bex
\bxi
\bit
\bt [_
\bn]
4420 Cause the shell to exit with a status of _
\bn. If _
\bn is omitted,
4421 the exit status is that of the last command executed. A trap on
4422 E
\bEX
\bXI
\bIT
\bT is executed before the shell terminates.
4424 e
\bex
\bxp
\bpo
\bor
\brt
\bt [-
\b-f
\bfn
\bn] [_
\bn_
\ba_
\bm_
\be[=_
\bw_
\bo_
\br_
\bd]] ...
4425 e
\bex
\bxp
\bpo
\bor
\brt
\bt -
\b-p
\bp
4426 The supplied _
\bn_
\ba_
\bm_
\be_
\bs are marked for automatic export to the envi-
4427 ronment of subsequently executed commands. If the -
\b-f
\bf option is
4428 given, the _
\bn_
\ba_
\bm_
\be_
\bs refer to functions. If no _
\bn_
\ba_
\bm_
\be_
\bs are given, or
4429 if the -
\b-p
\bp option is supplied, a list of names of all exported
4430 variables is printed. The -
\b-n
\bn option causes the export property
4431 to be removed from each _
\bn_
\ba_
\bm_
\be. If a variable name is followed by
4432 =_
\bw_
\bo_
\br_
\bd, the value of the variable is set to _
\bw_
\bo_
\br_
\bd. e
\bex
\bxp
\bpo
\bor
\brt
\bt returns
4433 an exit status of 0 unless an invalid option is encountered, one
4434 of the _
\bn_
\ba_
\bm_
\be_
\bs is not a valid shell variable name, or -
\b-f
\bf is sup-
4435 plied with a _
\bn_
\ba_
\bm_
\be that is not a function.
4437 f
\bfc
\bc [-
\b-e
\be _
\be_
\bn_
\ba_
\bm_
\be] [-
\b-l
\bln
\bnr
\br] [_
\bf_
\bi_
\br_
\bs_
\bt] [_
\bl_
\ba_
\bs_
\bt]
4438 f
\bfc
\bc -
\b-s
\bs [_
\bp_
\ba_
\bt=_
\br_
\be_
\bp] [_
\bc_
\bm_
\bd]
4439 The first form selects a range of commands from _
\bf_
\bi_
\br_
\bs_
\bt to _
\bl_
\ba_
\bs_
\bt
4440 from the history list and displays or edits and re-executes
4441 them. _
\bF_
\bi_
\br_
\bs_
\bt and _
\bl_
\ba_
\bs_
\bt may be specified as a string (to locate
4442 the last command beginning with that string) or as a number (an
4443 index into the history list, where a negative number is used as
4444 an offset from the current command number). If _
\bl_
\ba_
\bs_
\bt is not
4445 specified it is set to the current command for listing (so that
4446 ``fc -l -10'' prints the last 10 commands) and to _
\bf_
\bi_
\br_
\bs_
\bt other-
4447 wise. If _
\bf_
\bi_
\br_
\bs_
\bt is not specified it is set to the previous com-
4448 mand for editing and -16 for listing.
4450 The -
\b-n
\bn option suppresses the command numbers when listing. The
4451 -
\b-r
\br option reverses the order of the commands. If the -
\b-l
\bl option
4452 is given, the commands are listed on standard output. Other-
4453 wise, the editor given by _
\be_
\bn_
\ba_
\bm_
\be is invoked on a file containing
4454 those commands. If _
\be_
\bn_
\ba_
\bm_
\be is not given, the value of the F
\bFC
\bCE
\bED
\bDI
\bIT
\bT
4455 variable is used, and the value of E
\bED
\bDI
\bIT
\bTO
\bOR
\bR if F
\bFC
\bCE
\bED
\bDI
\bIT
\bT is not set.
4456 If neither variable is set, _
\bv_
\bi is used. When editing is com-
4457 plete, the edited commands are echoed and executed.
4459 In the second form, _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is re-executed after each instance
4460 of _
\bp_
\ba_
\bt is replaced by _
\br_
\be_
\bp. _
\bC_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd is intepreted the same as
4461 _
\bf_
\bi_
\br_
\bs_
\bt above. A useful alias to use with this is ``r="fc -s"'',
4462 so that typing ``r cc'' runs the last command beginning with
4463 ``cc'' and typing ``r'' re-executes the last command.
4465 If the first form is used, the return value is 0 unless an
4466 invalid option is encountered or _
\bf_
\bi_
\br_
\bs_
\bt or _
\bl_
\ba_
\bs_
\bt specify history
4467 lines out of range. If the -
\b-e
\be option is supplied, the return
4468 value is the value of the last command executed or failure if an
4469 error occurs with the temporary file of commands. If the second
4470 form is used, the return status is that of the command re-exe-
4471 cuted, unless _
\bc_
\bm_
\bd does not specify a valid history line, in
4472 which case f
\bfc
\bc returns failure.
4474 f
\bfg
\bg [_
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc]
4475 Resume _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc in the foreground, and make it the current job.
4476 If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is not present, the shell's notion of the _
\bc_
\bu_
\br_
\br_
\be_
\bn_
\bt _
\bj_
\bo_
\bb
4477 is used. The return value is that of the command placed into
4478 the foreground, or failure if run when job control is disabled
4479 or, when run with job control enabled, if _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc does not spec-
4480 ify a valid job or _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc specifies a job that was started
4481 without job control.
4483 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg _
\bn_
\ba_
\bm_
\be [_
\ba_
\br_
\bg_
\bs]
4484 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs is used by shell procedures to parse positional parame-
4485 ters. _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg contains the option characters to be recog-
4486 nized; if a character is followed by a colon, the option is
4487 expected to have an argument, which should be separated from it
4488 by white space. The colon and question mark characters may not
4489 be used as option characters. Each time it is invoked, g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs
4490 places the next option in the shell variable _
\bn_
\ba_
\bm_
\be, initializing
4491 _
\bn_
\ba_
\bm_
\be if it does not exist, and the index of the next argument to
4492 be processed into the variable O
\bOP
\bPT
\bTI
\bIN
\bND
\bD. O
\bOP
\bPT
\bTI
\bIN
\bND
\bD is initialized to
4493 1 each time the shell or a shell script is invoked. When an
4494 option requires an argument, g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs places that argument into
4495 the variable O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG. The shell does not reset O
\bOP
\bPT
\bTI
\bIN
\bND
\bD automati-
4496 cally; it must be manually reset between multiple calls to
4497 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs within the same shell invocation if a new set of parame-
4500 When the end of options is encountered, g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs exits with a
4501 return value greater than zero. O
\bOP
\bPT
\bTI
\bIN
\bND
\bD is set to the index of
4502 the first non-option argument, and _
\bn_
\ba_
\bm_
\be is set to ?.
4504 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs normally parses the positional parameters, but if more
4505 arguments are given in _
\ba_
\br_
\bg_
\bs, g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs parses those instead.
4507 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs can report errors in two ways. If the first character
4508 of _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg is a colon, _
\bs_
\bi_
\bl_
\be_
\bn_
\bt error reporting is used. In
4509 normal operation, diagnostic messages are printed when invalid
4510 options or missing option arguments are encountered. If the
4511 variable O
\bOP
\bPT
\bTE
\bER
\bRR
\bR is set to 0, no error messages will be dis-
4512 played, even if the first character of _
\bo_
\bp_
\bt_
\bs_
\bt_
\br_
\bi_
\bn_
\bg is not a colon.
4514 If an invalid option is seen, g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs places ? into _
\bn_
\ba_
\bm_
\be and, if
4515 not silent, prints an error message and unsets O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG. If
4516 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs is silent, the option character found is placed in
4517 O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG and no diagnostic message is printed.
4519 If a required argument is not found, and g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs is not silent,
4520 a question mark (?
\b?) is placed in _
\bn_
\ba_
\bm_
\be, O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG is unset, and a
4521 diagnostic message is printed. If g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs is silent, then a
4522 colon (:
\b:) is placed in _
\bn_
\ba_
\bm_
\be and O
\bOP
\bPT
\bTA
\bAR
\bRG
\bG is set to the option
4525 g
\bge
\bet
\bto
\bop
\bpt
\bts
\bs returns true if an option, specified or unspecified, is
4526 found. It returns false if the end of options is encountered or
4529 h
\bha
\bas
\bsh
\bh [-
\b-l
\blr
\br] [-
\b-p
\bp _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be] [-
\b-d
\bdt
\bt] [_
\bn_
\ba_
\bm_
\be]
4530 Each time h
\bha
\bas
\bsh
\bh is invoked, the full pathname of the command _
\bn_
\ba_
\bm_
\be
4531 is determined by searching the directories in $
\b$P
\bPA
\bAT
\bTH
\bH and remem-
4532 bered. Any previously-remembered pathname is discarded. If the
4533 -
\b-p
\bp option is supplied, no path search is performed, and _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be
4534 is used as the full filename of the command. The -
\b-r
\br option
4535 causes the shell to forget all remembered locations. The -
\b-d
\bd
4536 option causes the shell to forget the remembered location of
4537 each _
\bn_
\ba_
\bm_
\be. If the -
\b-t
\bt option is supplied, the full pathname to
4538 which each _
\bn_
\ba_
\bm_
\be corresponds is printed. If multiple _
\bn_
\ba_
\bm_
\be argu-
4539 ments are supplied with -
\b-t
\bt, the _
\bn_
\ba_
\bm_
\be is printed before the
4540 hashed full pathname. The -
\b-l
\bl option causes output to be dis-
4541 played in a format that may be reused as input. If no arguments
4542 are given, or if only -
\b-l
\bl is supplied, information about remem-
4543 bered commands is printed. The return status is true unless a
4544 _
\bn_
\ba_
\bm_
\be is not found or an invalid option is supplied.
4546 h
\bhe
\bel
\blp
\bp [-
\b-d
\bdm
\bms
\bs] [_
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn]
4547 Display helpful information about builtin commands. If _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn
4548 is specified, h
\bhe
\bel
\blp
\bp gives detailed help on all commands matching
4549 _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn; otherwise help for all the builtins and shell control
4550 structures is printed.
4551 -
\b-d
\bd Display a short description of each _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn
4552 -
\b-m
\bm Display the description of each _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn in a manpage-like
4554 -
\b-s
\bs Display only a short usage synopsis for each _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn
4556 The return status is 0 unless no command matches _
\bp_
\ba_
\bt_
\bt_
\be_
\br_
\bn.
4558 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by [
\b[_
\bn]
\b]
4559 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by -
\b-c
\bc
4560 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by -
\b-d
\bd _
\bo_
\bf_
\bf_
\bs_
\be_
\bt
4561 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by -
\b-a
\ban
\bnr
\brw
\bw [_
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be]
4562 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by -
\b-p
\bp _
\ba_
\br_
\bg [_
\ba_
\br_
\bg _
\b._
\b._
\b.]
4563 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by -
\b-s
\bs _
\ba_
\br_
\bg [_
\ba_
\br_
\bg _
\b._
\b._
\b.]
4564 With no options, display the command history list with line num-
4565 bers. Lines listed with a *
\b* have been modified. An argument of
4566 _
\bn lists only the last _
\bn lines. If the shell variable H
\bHI
\bIS
\bST
\bTT
\bTI
\bIM
\bME
\bE-
\b-
4567 F
\bFO
\bOR
\bRM
\bMA
\bAT
\bT is set and not null, it is used as a format string for
4568 _
\bs_
\bt_
\br_
\bf_
\bt_
\bi_
\bm_
\be(3) to display the time stamp associated with each dis-
4569 played history entry. No intervening blank is printed between
4570 the formatted time stamp and the history line. If _
\bf_
\bi_
\bl_
\be_
\bn_
\ba_
\bm_
\be is
4571 supplied, it is used as the name of the history file; if not,
4572 the value of H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE is used. Options, if supplied, have the
4574 -
\b-c
\bc Clear the history list by deleting all the entries.
4575 -
\b-d
\bd _
\bo_
\bf_
\bf_
\bs_
\be_
\bt
4576 Delete the history entry at position _
\bo_
\bf_
\bf_
\bs_
\be_
\bt.
4577 -
\b-a
\ba Append the ``new'' history lines (history lines entered
4578 since the beginning of the current b
\bba
\bas
\bsh
\bh session) to the
4580 -
\b-n
\bn Read the history lines not already read from the history
4581 file into the current history list. These are lines
4582 appended to the history file since the beginning of the
4583 current b
\bba
\bas
\bsh
\bh session.
4584 -
\b-r
\br Read the contents of the history file and append them to
4585 the current history list.
4586 -
\b-w
\bw Write the current history list to the history file, over-
4587 writing the history file's contents.
4588 -
\b-p
\bp Perform history substitution on the following _
\ba_
\br_
\bg_
\bs and
4589 display the result on the standard output. Does not
4590 store the results in the history list. Each _
\ba_
\br_
\bg must be
4591 quoted to disable normal history expansion.
4592 -
\b-s
\bs Store the _
\ba_
\br_
\bg_
\bs in the history list as a single entry.
4593 The last command in the history list is removed before
4594 the _
\ba_
\br_
\bg_
\bs are added.
4596 If the H
\bHI
\bIS
\bST
\bTT
\bTI
\bIM
\bME
\bEF
\bFO
\bOR
\bRM
\bMA
\bAT
\bT variable is set, the time stamp informa-
4597 tion associated with each history entry is written to the his-
4598 tory file, marked with the history comment character. When the
4599 history file is read, lines beginning with the history comment
4600 character followed immediately by a digit are interpreted as
4601 timestamps for the previous history line. The return value is 0
4602 unless an invalid option is encountered, an error occurs while
4603 reading or writing the history file, an invalid _
\bo_
\bf_
\bf_
\bs_
\be_
\bt is sup-
4604 plied as an argument to -
\b-d
\bd, or the history expansion supplied as
4605 an argument to -
\b-p
\bp fails.
4607 j
\bjo
\bob
\bbs
\bs [-
\b-l
\bln
\bnp
\bpr
\brs
\bs] [ _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc ... ]
4608 j
\bjo
\bob
\bbs
\bs -
\b-x
\bx _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd [ _
\ba_
\br_
\bg_
\bs ... ]
4609 The first form lists the active jobs. The options have the fol-
4611 -
\b-l
\bl List process IDs in addition to the normal information.
4612 -
\b-n
\bn Display information only about jobs that have changed
4613 status since the user was last notified of their status.
4614 -
\b-p
\bp List only the process ID of the job's process group
4616 -
\b-r
\br Display only running jobs.
4617 -
\b-s
\bs Display only stopped jobs.
4619 If _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is given, output is restricted to information about
4620 that job. The return status is 0 unless an invalid option is
4621 encountered or an invalid _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc is supplied.
4623 If the -
\b-x
\bx option is supplied, j
\bjo
\bob
\bbs
\bs replaces any _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc found in
4624 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd or _
\ba_
\br_
\bg_
\bs with the corresponding process group ID, and
4625 executes _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd passing it _
\ba_
\br_
\bg_
\bs, returning its exit status.
4627 k
\bki
\bil
\bll
\bl [-
\b-s
\bs _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc | -
\b-n
\bn _
\bs_
\bi_
\bg_
\bn_
\bu_
\bm | -
\b-_
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc] [_
\bp_
\bi_
\bd | _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc] ...
4628 k
\bki
\bil
\bll
\bl -
\b-l
\bl [_
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc | _
\be_
\bx_
\bi_
\bt_
\b__
\bs_
\bt_
\ba_
\bt_
\bu_
\bs]
4629 Send the signal named by _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc or _
\bs_
\bi_
\bg_
\bn_
\bu_
\bm to the processes
4630 named by _
\bp_
\bi_
\bd or _
\bj_
\bo_
\bb_
\bs_
\bp_
\be_
\bc. _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is either a case-insensitive
4631 signal name such as S
\bSI
\bIG
\bGK
\bKI
\bIL
\bLL
\bL (with or without the S
\bSI
\bIG
\bG prefix) or
4632 a signal number; _
\bs_
\bi_
\bg_
\bn_
\bu_
\bm is a signal number. If _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is not
4633 present, then S
\bSI
\bIG
\bGT
\bTE
\bER
\bRM
\bM is assumed. An argument of -
\b-l
\bl lists the
4634 signal names. If any arguments are supplied when -
\b-l
\bl is given,
4635 the names of the signals corresponding to the arguments are
4636 listed, and the return status is 0. The _
\be_
\bx_
\bi_
\bt_
\b__
\bs_
\bt_
\ba_
\bt_
\bu_
\bs argument to
4637 -
\b-l
\bl is a number specifying either a signal number or the exit
4638 status of a process terminated by a signal. k
\bki
\bil
\bll
\bl returns true
4639 if at least one signal was successfully sent, or false if an
4640 error occurs or an invalid option is encountered.
4642 l
\ble
\bet
\bt _
\ba_
\br_
\bg [_
\ba_
\br_
\bg ...]
4643 Each _
\ba_
\br_
\bg is an arithmetic expression to be evaluated (see A
\bAR
\bRI
\bIT
\bTH
\bH-
\b-
4644 M
\bME
\bET
\bTI
\bIC
\bC E
\bEV
\bVA
\bAL
\bLU
\bUA
\bAT
\bTI
\bIO
\bON
\bN above). If the last _
\ba_
\br_
\bg evaluates to 0, l
\ble
\bet
\bt
4645 returns 1; 0 is returned otherwise.
4647 l
\blo
\boc
\bca
\bal
\bl [_
\bo_
\bp_
\bt_
\bi_
\bo_
\bn] [_
\bn_
\ba_
\bm_
\be[=_
\bv_
\ba_
\bl_
\bu_
\be] ...]
4648 For each argument, a local variable named _
\bn_
\ba_
\bm_
\be is created, and
4649 assigned _
\bv_
\ba_
\bl_
\bu_
\be. The _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn can be any of the options accepted
4650 by d
\bde
\bec
\bcl
\bla
\bar
\bre
\be. When l
\blo
\boc
\bca
\bal
\bl is used within a function, it causes the
4651 variable _
\bn_
\ba_
\bm_
\be to have a visible scope restricted to that func-
4652 tion and its children. With no operands, l
\blo
\boc
\bca
\bal
\bl writes a list of
4653 local variables to the standard output. It is an error to use
4654 l
\blo
\boc
\bca
\bal
\bl when not within a function. The return status is 0 unless
4655 l
\blo
\boc
\bca
\bal
\bl is used outside a function, an invalid _
\bn_
\ba_
\bm_
\be is supplied,
4656 or _
\bn_
\ba_
\bm_
\be is a readonly variable.
4658 l
\blo
\bog
\bgo
\bou
\but
\bt Exit a login shell.
4660 m
\bma
\bap
\bpf
\bfi
\bil
\ble
\be [-
\b-n
\bn _
\bc_
\bo_
\bu_
\bn_
\bt] [-
\b-O
\bO _
\bo_
\br_
\bi_
\bg_
\bi_
\bn] [-
\b-s
\bs _
\bc_
\bo_
\bu_
\bn_
\bt] [-
\b-t
\bt] [-
\b-u
\bu _
\bf_
\bd] [-
\b-C
\bC _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk]
4661 [-
\b-c
\bc _
\bq_
\bu_
\ba_
\bn_
\bt_
\bu_
\bm] [_
\ba_
\br_
\br_
\ba_
\by]
4662 r
\bre
\bea
\bad
\bda
\bar
\brr
\bra
\bay
\by [-
\b-n
\bn _
\bc_
\bo_
\bu_
\bn_
\bt] [-
\b-O
\bO _
\bo_
\br_
\bi_
\bg_
\bi_
\bn] [-
\b-s
\bs _
\bc_
\bo_
\bu_
\bn_
\bt] [-
\b-t
\bt] [-
\b-u
\bu _
\bf_
\bd] [-
\b-C
\bC _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk]
4663 [-
\b-c
\bc _
\bq_
\bu_
\ba_
\bn_
\bt_
\bu_
\bm] [_
\ba_
\br_
\br_
\ba_
\by]
4664 Read lines from the standard input into the indexed array vari-
4665 able _
\ba_
\br_
\br_
\ba_
\by, or from file descriptor _
\bf_
\bd if the -
\b-u
\bu option is sup-
4666 plied. The variable M
\bMA
\bAP
\bPF
\bFI
\bIL
\bLE
\bE is the default _
\ba_
\br_
\br_
\ba_
\by. Options, if
4667 supplied, have the following meanings:
4668 -
\b-n
\bn Copy at most _
\bc_
\bo_
\bu_
\bn_
\bt lines. If _
\bc_
\bo_
\bu_
\bn_
\bt is 0, all lines are
4670 -
\b-O
\bO Begin assigning to _
\ba_
\br_
\br_
\ba_
\by at index _
\bo_
\br_
\bi_
\bg_
\bi_
\bn. The default
4672 -
\b-s
\bs Discard the first _
\bc_
\bo_
\bu_
\bn_
\bt lines read.
4673 -
\b-t
\bt Remove a trailing newline from each line read.
4674 -
\b-u
\bu Read lines from file descriptor _
\bf_
\bd instead of the stan-
4676 -
\b-C
\bC Evaluate _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk each time _
\bq_
\bu_
\ba_
\bn_
\bt_
\bu_
\bm lines are read. The
4677 -
\b-c
\bc option specifies _
\bq_
\bu_
\ba_
\bn_
\bt_
\bu_
\bm.
4678 -
\b-c
\bc Specify the number of lines read between each call to
4679 _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk.
4681 If -
\b-C
\bC is specified without -
\b-c
\bc, the default quantum is 5000.
4682 When _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk is evaluated, it is supplied the index of the next
4683 array element to be assigned and the line to be assigned to that
4684 element as additional arguments. _
\bc_
\ba_
\bl_
\bl_
\bb_
\ba_
\bc_
\bk is evaluated after
4685 the line is read but before the array element is assigned.
4687 If not supplied with an explicit origin, m
\bma
\bap
\bpf
\bfi
\bil
\ble
\be will clear
4688 _
\ba_
\br_
\br_
\ba_
\by before assigning to it.
4690 m
\bma
\bap
\bpf
\bfi
\bil
\ble
\be returns successfully unless an invalid option or option
4691 argument is supplied, _
\ba_
\br_
\br_
\ba_
\by is invalid or unassignable, or if
4692 _
\ba_
\br_
\br_
\ba_
\by is not an indexed array.
4694 p
\bpo
\bop
\bpd
\bd [-n
\bn] [+_
\bn] [-_
\bn]
4695 Removes entries from the directory stack. With no arguments,
4696 removes the top directory from the stack, and performs a c
\bcd
\bd to
4697 the new top directory. Arguments, if supplied, have the follow-
4699 -
\b-n
\bn Suppresses the normal change of directory when removing
4700 directories from the stack, so that only the stack is
4702 +
\b+_
\bn Removes the _
\bnth entry counting from the left of the list
4703 shown by d
\bdi
\bir
\brs
\bs, starting with zero. For example: ``popd
4704 +0'' removes the first directory, ``popd +1'' the second.
4705 -
\b-_
\bn Removes the _
\bnth entry counting from the right of the list
4706 shown by d
\bdi
\bir
\brs
\bs, starting with zero. For example: ``popd
4707 -0'' removes the last directory, ``popd -1'' the next to
4710 If the p
\bpo
\bop
\bpd
\bd command is successful, a d
\bdi
\bir
\brs
\bs is performed as well,
4711 and the return status is 0. p
\bpo
\bop
\bpd
\bd returns false if an invalid
4712 option is encountered, the directory stack is empty, a non-exis-
4713 tent directory stack entry is specified, or the directory change
4716 p
\bpr
\bri
\bin
\bnt
\btf
\bf [-
\b-v
\bv _
\bv_
\ba_
\br] _
\bf_
\bo_
\br_
\bm_
\ba_
\bt [_
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs]
4717 Write the formatted _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs to the standard output under the
4718 control of the _
\bf_
\bo_
\br_
\bm_
\ba_
\bt. The -
\b-v
\bv option causes the output to be
4719 assigned to the variable _
\bv_
\ba_
\br rather than being printed to the
4722 The _
\bf_
\bo_
\br_
\bm_
\ba_
\bt is a character string which contains three types of
4723 objects: plain characters, which are simply copied to standard
4724 output, character escape sequences, which are converted and
4725 copied to the standard output, and format specifications, each
4726 of which causes printing of the next successive _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt. In
4727 addition to the standard _
\bp_
\br_
\bi_
\bn_
\bt_
\bf(1) format specifications, p
\bpr
\bri
\bin
\bnt
\btf
\bf
4728 interprets the following extensions:
4729 %
\b%b
\bb causes p
\bpr
\bri
\bin
\bnt
\btf
\bf to expand backslash escape sequences in the
4730 corresponding _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt (except that \
\b\c
\bc terminates output,
4731 backslashes in \
\b\'
\b', \
\b\"
\b", and \
\b\?
\b? are not removed, and octal
4732 escapes beginning with \
\b\0
\b0 may contain up to four digits).
4733 %
\b%q
\bq causes p
\bpr
\bri
\bin
\bnt
\btf
\bf to output the corresponding _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt in a
4734 format that can be reused as shell input.
4735 %
\b%(
\b(_
\bd_
\ba_
\bt_
\be_
\bf_
\bm_
\bt)
\b)T
\bT
4736 causes p
\bpr
\bri
\bin
\bnt
\btf
\bf to output the date-time string resulting
4737 from using _
\bd_
\ba_
\bt_
\be_
\bf_
\bm_
\bt as a format string for _
\bs_
\bt_
\br_
\bf_
\bt_
\bi_
\bm_
\be(3).
4738 The corresponding _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt is an integer representing the
4739 number of seconds since the epoch. Two special argument
4740 values may be used: -1 represents the current time, and
4741 -2 represents the time the shell was invoked. If no
4742 argument is specified, conversion behaves as if -1 had
4743 been given. This is an exception to the usual p
\bpr
\bri
\bin
\bnt
\btf
\bf
4746 Arguments to non-string format specifiers are treated as C con-
4747 stants, except that a leading plus or minus sign is allowed, and
4748 if the leading character is a single or double quote, the value
4749 is the ASCII value of the following character.
4751 The _
\bf_
\bo_
\br_
\bm_
\ba_
\bt is reused as necessary to consume all of the _
\ba_
\br_
\bg_
\bu_
\b-
4752 _
\bm_
\be_
\bn_
\bt_
\bs. If the _
\bf_
\bo_
\br_
\bm_
\ba_
\bt requires more _
\ba_
\br_
\bg_
\bu_
\bm_
\be_
\bn_
\bt_
\bs than are supplied,
4753 the extra format specifications behave as if a zero value or
4754 null string, as appropriate, had been supplied. The return
4755 value is zero on success, non-zero on failure.
4757 p
\bpu
\bus
\bsh
\bhd
\bd [-
\b-n
\bn] [+_
\bn] [-_
\bn]
4758 p
\bpu
\bus
\bsh
\bhd
\bd [-
\b-n
\bn] [_
\bd_
\bi_
\br]
4759 Adds a directory to the top of the directory stack, or rotates
4760 the stack, making the new top of the stack the current working
4761 directory. With no arguments, exchanges the top two directories
4762 and returns 0, unless the directory stack is empty. Arguments,
4763 if supplied, have the following meanings:
4764 -
\b-n
\bn Suppresses the normal change of directory when adding
4765 directories to the stack, so that only the stack is
4767 +
\b+_
\bn Rotates the stack so that the _
\bnth directory (counting
4768 from the left of the list shown by d
\bdi
\bir
\brs
\bs, starting with
4769 zero) is at the top.
4770 -
\b-_
\bn Rotates the stack so that the _
\bnth directory (counting
4771 from the right of the list shown by d
\bdi
\bir
\brs
\bs, starting with
4772 zero) is at the top.
4773 _
\bd_
\bi_
\br Adds _
\bd_
\bi_
\br to the directory stack at the top, making it the
4774 new current working directory as if it had been supplied
4775 as the argument to the c
\bcd
\bd builtin.
4777 If the p
\bpu
\bus
\bsh
\bhd
\bd command is successful, a d
\bdi
\bir
\brs
\bs is performed as well.
4778 If the first form is used, p
\bpu
\bus
\bsh
\bhd
\bd returns 0 unless the cd to _
\bd_
\bi_
\br
4779 fails. With the second form, p
\bpu
\bus
\bsh
\bhd
\bd returns 0 unless the direc-
4780 tory stack is empty, a non-existent directory stack element is
4781 specified, or the directory change to the specified new current
4784 p
\bpw
\bwd
\bd [-
\b-L
\bLP
\bP]
4785 Print the absolute pathname of the current working directory.
4786 The pathname printed contains no symbolic links if the -
\b-P
\bP option
4787 is supplied or the -
\b-o
\bo p
\bph
\bhy
\bys
\bsi
\bic
\bca
\bal
\bl option to the s
\bse
\bet
\bt builtin command
4788 is enabled. If the -
\b-L
\bL option is used, the pathname printed may
4789 contain symbolic links. The return status is 0 unless an error
4790 occurs while reading the name of the current directory or an
4791 invalid option is supplied.
4793 r
\bre
\bea
\bad
\bd [-
\b-e
\ber
\brs
\bs] [-
\b-a
\ba _
\ba_
\bn_
\ba_
\bm_
\be] [-
\b-d
\bd _
\bd_
\be_
\bl_
\bi_
\bm] [-
\b-i
\bi _
\bt_
\be_
\bx_
\bt] [-
\b-n
\bn _
\bn_
\bc_
\bh_
\ba_
\br_
\bs] [-
\b-N
\bN _
\bn_
\bc_
\bh_
\ba_
\br_
\bs] [-
\b-p
\bp
4794 _
\bp_
\br_
\bo_
\bm_
\bp_
\bt] [-
\b-t
\bt _
\bt_
\bi_
\bm_
\be_
\bo_
\bu_
\bt] [-
\b-u
\bu _
\bf_
\bd] [_
\bn_
\ba_
\bm_
\be ...]
4795 One line is read from the standard input, or from the file
4796 descriptor _
\bf_
\bd supplied as an argument to the -
\b-u
\bu option, and the
4797 first word is assigned to the first _
\bn_
\ba_
\bm_
\be, the second word to the
4798 second _
\bn_
\ba_
\bm_
\be, and so on, with leftover words and their interven-
4799 ing separators assigned to the last _
\bn_
\ba_
\bm_
\be. If there are fewer
4800 words read from the input stream than names, the remaining names
4801 are assigned empty values. The characters in I
\bIF
\bFS
\bS are used to
4802 split the line into words using the same rules the shell uses
4803 for expansion (described above under W
\bWo
\bor
\brd
\bd S
\bSp
\bpl
\bli
\bit
\btt
\bti
\bin
\bng
\bg). The back-
4804 slash character (\
\b\) may be used to remove any special meaning
4805 for the next character read and for line continuation. Options,
4806 if supplied, have the following meanings:
4807 -
\b-a
\ba _
\ba_
\bn_
\ba_
\bm_
\be
4808 The words are assigned to sequential indices of the array
4809 variable _
\ba_
\bn_
\ba_
\bm_
\be, starting at 0. _
\ba_
\bn_
\ba_
\bm_
\be is unset before any
4810 new values are assigned. Other _
\bn_
\ba_
\bm_
\be arguments are
4812 -
\b-d
\bd _
\bd_
\be_
\bl_
\bi_
\bm
4813 The first character of _
\bd_
\be_
\bl_
\bi_
\bm is used to terminate the
4814 input line, rather than newline.
4815 -
\b-e
\be If the standard input is coming from a terminal, r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be
4816 (see R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE above) is used to obtain the line. Read-
4817 line uses the current (or default, if line editing was
4818 not previously active) editing settings.
4819 -
\b-i
\bi _
\bt_
\be_
\bx_
\bt
4820 If r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used to read the line, _
\bt_
\be_
\bx_
\bt is
4821 placed into the editing buffer before editing begins.
4822 -
\b-n
\bn _
\bn_
\bc_
\bh_
\ba_
\br_
\bs
4823 r
\bre
\bea
\bad
\bd returns after reading _
\bn_
\bc_
\bh_
\ba_
\br_
\bs characters rather than
4824 waiting for a complete line of input, but honor a delim-
4825 iter if fewer than _
\bn_
\bc_
\bh_
\ba_
\br_
\bs characters are read before the
4827 -
\b-N
\bN _
\bn_
\bc_
\bh_
\ba_
\br_
\bs
4828 r
\bre
\bea
\bad
\bd returns after reading exactly _
\bn_
\bc_
\bh_
\ba_
\br_
\bs characters
4829 rather than waiting for a complete line of input, unless
4830 EOF is encountered or r
\bre
\bea
\bad
\bd times out. Delimiter charac-
4831 ters encountered in the input are not treated specially
4832 and do not cause r
\bre
\bea
\bad
\bd to return until _
\bn_
\bc_
\bh_
\ba_
\br_
\bs characters
4834 -
\b-p
\bp _
\bp_
\br_
\bo_
\bm_
\bp_
\bt
4835 Display _
\bp_
\br_
\bo_
\bm_
\bp_
\bt on standard error, without a trailing new-
4836 line, before attempting to read any input. The prompt is
4837 displayed only if input is coming from a terminal.
4838 -
\b-r
\br Backslash does not act as an escape character. The back-
4839 slash is considered to be part of the line. In particu-
4840 lar, a backslash-newline pair may not be used as a line
4842 -
\b-s
\bs Silent mode. If input is coming from a terminal, charac-
4843 ters are not echoed.
4844 -
\b-t
\bt _
\bt_
\bi_
\bm_
\be_
\bo_
\bu_
\bt
4845 Cause r
\bre
\bea
\bad
\bd to time out and return failure if a complete
4846 line of input (or a specified number of characters) is
4847 not read within _
\bt_
\bi_
\bm_
\be_
\bo_
\bu_
\bt seconds. _
\bt_
\bi_
\bm_
\be_
\bo_
\bu_
\bt may be a deci-
4848 mal number with a fractional portion following the deci-
4849 mal point. This option is only effective if r
\bre
\bea
\bad
\bd is
4850 reading input from a terminal, pipe, or other special
4851 file; it has no effect when reading from regular files.
4852 If r
\bre
\bea
\bad
\bd times out, r
\bre
\bea
\bad
\bd saves any partial input read into
4853 the specified variable _
\bn_
\ba_
\bm_
\be. If _
\bt_
\bi_
\bm_
\be_
\bo_
\bu_
\bt is 0, r
\bre
\bea
\bad
\bd
4854 returns immediately, without trying to read any data.
4855 The exit status is 0 if input is available on the speci-
4856 fied file descriptor, non-zero otherwise. The exit sta-
4857 tus is greater than 128 if the timeout is exceeded.
4858 -
\b-u
\bu _
\bf_
\bd Read input from file descriptor _
\bf_
\bd.
4860 If no _
\bn_
\ba_
\bm_
\be_
\bs are supplied, the line read is assigned to the vari-
4861 able R
\bRE
\bEP
\bPL
\bLY
\bY. The return code is zero, unless end-of-file is
4862 encountered, r
\bre
\bea
\bad
\bd times out (in which case the return code is
4863 greater than 128), a variable assignment error (such as assign-
4864 ing to a readonly variable) occurs, or an invalid file descrip-
4865 tor is supplied as the argument to -
\b-u
\bu.
4867 r
\bre
\bea
\bad
\bdo
\bon
\bnl
\bly
\by [-
\b-a
\baA
\bAf
\bf] [-
\b-p
\bp] [_
\bn_
\ba_
\bm_
\be[=_
\bw_
\bo_
\br_
\bd] ...]
4868 The given _
\bn_
\ba_
\bm_
\be_
\bs are marked readonly; the values of these _
\bn_
\ba_
\bm_
\be_
\bs
4869 may not be changed by subsequent assignment. If the -
\b-f
\bf option
4870 is supplied, the functions corresponding to the _
\bn_
\ba_
\bm_
\be_
\bs are so
4871 marked. The -
\b-a
\ba option restricts the variables to indexed
4872 arrays; the -
\b-A
\bA option restricts the variables to associative
4873 arrays. If both options are supplied, -
\b-A
\bA takes precedence. If
4874 no _
\bn_
\ba_
\bm_
\be arguments are given, or if the -
\b-p
\bp option is supplied, a
4875 list of all readonly names is printed. The other options may be
4876 used to restrict the output to a subset of the set of readonly
4877 names. The -
\b-p
\bp option causes output to be displayed in a format
4878 that may be reused as input. If a variable name is followed by
4879 =_
\bw_
\bo_
\br_
\bd, the value of the variable is set to _
\bw_
\bo_
\br_
\bd. The return
4880 status is 0 unless an invalid option is encountered, one of the
4881 _
\bn_
\ba_
\bm_
\be_
\bs is not a valid shell variable name, or -
\b-f
\bf is supplied with
4882 a _
\bn_
\ba_
\bm_
\be that is not a function.
4884 r
\bre
\bet
\btu
\bur
\brn
\bn [_
\bn]
4885 Causes a function to stop executing and return the value speci-
4886 fied by _
\bn to its caller. If _
\bn is omitted, the return status is
4887 that of the last command executed in the function body. If
4888 r
\bre
\bet
\btu
\bur
\brn
\bn is used outside a function, but during execution of a
4889 script by the .
\b. (s
\bso
\bou
\bur
\brc
\bce
\be) command, it causes the shell to stop
4890 executing that script and return either _
\bn or the exit status of
4891 the last command executed within the script as the exit status
4892 of the script. If _
\bn is supplied, the return value is its least
4893 significant 8 bits. The return status is non-zero if r
\bre
\bet
\btu
\bur
\brn
\bn is
4894 supplied a non-numeric argument, or is used outside a function
4895 and not during execution of a script by .
\b. or s
\bso
\bou
\bur
\brc
\bce
\be. Any com-
4896 mand associated with the R
\bRE
\bET
\bTU
\bUR
\bRN
\bN trap is executed before execu-
4897 tion resumes after the function or script.
4899 s
\bse
\bet
\bt [-
\b--
\b-a
\bab
\bbe
\bef
\bfh
\bhk
\bkm
\bmn
\bnp
\bpt
\btu
\buv
\bvx
\bxB
\bBC
\bCE
\bEH
\bHP
\bPT
\bT] [-
\b-o
\bo _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be] [_
\ba_
\br_
\bg ...]
4900 s
\bse
\bet
\bt [+
\b+a
\bab
\bbe
\bef
\bfh
\bhk
\bkm
\bmn
\bnp
\bpt
\btu
\buv
\bvx
\bxB
\bBC
\bCE
\bEH
\bHP
\bPT
\bT] [+
\b+o
\bo _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be] [_
\ba_
\br_
\bg ...]
4901 Without options, the name and value of each shell variable are
4902 displayed in a format that can be reused as input for setting or
4903 resetting the currently-set variables. Read-only variables can-
4904 not be reset. In _
\bp_
\bo_
\bs_
\bi_
\bx mode, only shell variables are listed.
4905 The output is sorted according to the current locale. When
4906 options are specified, they set or unset shell attributes. Any
4907 arguments remaining after option processing are treated as val-
4908 ues for the positional parameters and are assigned, in order, to
4909 $
\b$1
\b1, $
\b$2
\b2, .
\b..
\b..
\b. $
\b$_
\bn. Options, if specified, have the following
4911 -
\b-a
\ba Automatically mark variables and functions which are
4912 modified or created for export to the environment of
4913 subsequent commands.
4914 -
\b-b
\bb Report the status of terminated background jobs immedi-
4915 ately, rather than before the next primary prompt. This
4916 is effective only when job control is enabled.
4917 -
\b-e
\be Exit immediately if a _
\bp_
\bi_
\bp_
\be_
\bl_
\bi_
\bn_
\be (which may consist of a
4918 single _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd), a _
\bl_
\bi_
\bs_
\bt, or a _
\bc_
\bo_
\bm_
\bp_
\bo_
\bu_
\bn_
\bd _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd
4919 (see S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR above), exits with a non-zero sta-
4920 tus. The shell does not exit if the command that fails
4921 is part of the command list immediately following a
4922 w
\bwh
\bhi
\bil
\ble
\be or u
\bun
\bnt
\bti
\bil
\bl keyword, part of the test following the
4923 i
\bif
\bf or e
\bel
\bli
\bif
\bf reserved words, part of any command executed
4924 in a &
\b&&
\b& or |
\b||
\b| list except the command following the
4925 final &
\b&&
\b& or |
\b||
\b|, any command in a pipeline but the last,
4926 or if the command's return value is being inverted with
4927 !
\b!. If a compound command other than a subshell returns
4928 a non-zero status because a command failed while -
\b-e
\be was
4929 being ignored, the shell does not exit. A trap on E
\bER
\bRR
\bR,
4930 if set, is executed before the shell exits. This option
4931 applies to the shell environment and each subshell envi-
4932 ronment separately (see C
\bCO
\bOM
\bMM
\bMA
\bAN
\bND
\bD E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN E
\bEN
\bNV
\bVI
\bIR
\bRO
\bON
\bNM
\bME
\bEN
\bNT
\bT
4933 above), and may cause subshells to exit before executing
4934 all the commands in the subshell.
4936 If a compound command or shell function executes in a
4937 context where -
\b-e
\be is being ignored, none of the commands
4938 executed within the compound command or function body
4939 will be affected by the -
\b-e
\be setting, even if -
\b-e
\be is set
4940 and a command returns a failure status. If a compound
4941 command or shell function sets -
\b-e
\be while executing in a
4942 context where -
\b-e
\be is ignored, that setting will not have
4943 any effect until the compound command or the command
4944 containing the function call completes.
4945 -
\b-f
\bf Disable pathname expansion.
4946 -
\b-h
\bh Remember the location of commands as they are looked up
4947 for execution. This is enabled by default.
4948 -
\b-k
\bk All arguments in the form of assignment statements are
4949 placed in the environment for a command, not just those
4950 that precede the command name.
4951 -
\b-m
\bm Monitor mode. Job control is enabled. This option is
4952 on by default for interactive shells on systems that
4953 support it (see J
\bJO
\bOB
\bB C
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL above). All processes run
4954 in a separate process group. When a background job com-
4955 pletes, the shell prints a line containing its exit sta-
4957 -
\b-n
\bn Read commands but do not execute them. This may be used
4958 to check a shell script for syntax errors. This is
4959 ignored by interactive shells.
4960 -
\b-o
\bo _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be
4961 The _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be can be one of the following:
4962 a
\bal
\bll
\ble
\bex
\bxp
\bpo
\bor
\brt
\bt
4964 b
\bbr
\bra
\bac
\bce
\bee
\bex
\bxp
\bpa
\ban
\bnd
\bd
4966 e
\bem
\bma
\bac
\bcs
\bs Use an emacs-style command line editing inter-
4967 face. This is enabled by default when the shell
4968 is interactive, unless the shell is started with
4969 the -
\b--
\b-n
\bno
\boe
\bed
\bdi
\bit
\bti
\bin
\bng
\bg option. This also affects the
4970 editing interface used for r
\bre
\bea
\bad
\bd -
\b-e
\be.
4971 e
\ber
\brr
\bre
\bex
\bxi
\bit
\bt Same as -
\b-e
\be.
4972 e
\ber
\brr
\brt
\btr
\bra
\bac
\bce
\be
4974 f
\bfu
\bun
\bnc
\bct
\btr
\bra
\bac
\bce
\be
4976 h
\bha
\bas
\bsh
\bha
\bal
\bll
\bl Same as -
\b-h
\bh.
4977 h
\bhi
\bis
\bst
\bte
\bex
\bxp
\bpa
\ban
\bnd
\bd
4979 h
\bhi
\bis
\bst
\bto
\bor
\bry
\by Enable command history, as described above under
4980 H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY. This option is on by default in inter-
4982 i
\big
\bgn
\bno
\bor
\bre
\bee
\beo
\bof
\bf
4983 The effect is as if the shell command
4984 ``IGNOREEOF=10'' had been executed (see S
\bSh
\bhe
\bel
\bll
\bl
4985 V
\bVa
\bar
\bri
\bia
\bab
\bbl
\ble
\bes
\bs above).
4986 k
\bke
\bey
\byw
\bwo
\bor
\brd
\bd Same as -
\b-k
\bk.
4987 m
\bmo
\bon
\bni
\bit
\bto
\bor
\br Same as -
\b-m
\bm.
4988 n
\bno
\boc
\bcl
\blo
\bob
\bbb
\bbe
\ber
\br
4990 n
\bno
\boe
\bex
\bxe
\bec
\bc Same as -
\b-n
\bn.
4991 n
\bno
\bog
\bgl
\blo
\bob
\bb Same as -
\b-f
\bf.
4992 n
\bno
\bol
\blo
\bog
\bg Currently ignored.
4993 n
\bno
\bot
\bti
\bif
\bfy
\by Same as -
\b-b
\bb.
4994 n
\bno
\bou
\bun
\bns
\bse
\bet
\bt Same as -
\b-u
\bu.
4995 o
\bon
\bne
\bec
\bcm
\bmd
\bd Same as -
\b-t
\bt.
4996 p
\bph
\bhy
\bys
\bsi
\bic
\bca
\bal
\bl
4998 p
\bpi
\bip
\bpe
\bef
\bfa
\bai
\bil
\bl
4999 If set, the return value of a pipeline is the
5000 value of the last (rightmost) command to exit
5001 with a non-zero status, or zero if all commands
5002 in the pipeline exit successfully. This option
5003 is disabled by default.
5004 p
\bpo
\bos
\bsi
\bix
\bx Change the behavior of b
\bba
\bas
\bsh
\bh where the default
5005 operation differs from the POSIX standard to
5006 match the standard (_
\bp_
\bo_
\bs_
\bi_
\bx _
\bm_
\bo_
\bd_
\be). See S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
5007 below for a reference to a document that details
5008 how posix mode affects bash's behavior.
5009 p
\bpr
\bri
\biv
\bvi
\bil
\ble
\beg
\bge
\bed
\bd
5011 v
\bve
\ber
\brb
\bbo
\bos
\bse
\be Same as -
\b-v
\bv.
5012 v
\bvi
\bi Use a vi-style command line editing interface.
5013 This also affects the editing interface used for
5014 r
\bre
\bea
\bad
\bd -
\b-e
\be.
5015 x
\bxt
\btr
\bra
\bac
\bce
\be Same as -
\b-x
\bx.
5016 If -
\b-o
\bo is supplied with no _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be, the values of the
5017 current options are printed. If +
\b+o
\bo is supplied with no
5018 _
\bo_
\bp_
\bt_
\bi_
\bo_
\bn_
\b-_
\bn_
\ba_
\bm_
\be, a series of s
\bse
\bet
\bt commands to recreate the
5019 current option settings is displayed on the standard
5021 -
\b-p
\bp Turn on _
\bp_
\br_
\bi_
\bv_
\bi_
\bl_
\be_
\bg_
\be_
\bd mode. In this mode, the $
\b$E
\bEN
\bNV
\bV and
5022 $
\b$B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV files are not processed, shell functions are
5023 not inherited from the environment, and the S
\bSH
\bHE
\bEL
\bLL
\bLO
\bOP
\bPT
\bTS
\bS,
5024 B
\bBA
\bAS
\bSH
\bHO
\bOP
\bPT
\bTS
\bS, C
\bCD
\bDP
\bPA
\bAT
\bTH
\bH, and G
\bGL
\bLO
\bOB
\bBI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE variables, if they
5025 appear in the environment, are ignored. If the shell is
5026 started with the effective user (group) id not equal to
5027 the real user (group) id, and the -
\b-p
\bp option is not sup-
5028 plied, these actions are taken and the effective user id
5029 is set to the real user id. If the -
\b-p
\bp option is sup-
5030 plied at startup, the effective user id is not reset.
5031 Turning this option off causes the effective user and
5032 group ids to be set to the real user and group ids.
5033 -
\b-t
\bt Exit after reading and executing one command.
5034 -
\b-u
\bu Treat unset variables and parameters other than the spe-
5035 cial parameters "@" and "*" as an error when performing
5036 parameter expansion. If expansion is attempted on an
5037 unset variable or parameter, the shell prints an error
5038 message, and, if not interactive, exits with a non-zero
5040 -
\b-v
\bv Print shell input lines as they are read.
5041 -
\b-x
\bx After expanding each _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd, f
\bfo
\bor
\br command, c
\bca
\bas
\bse
\be
5042 command, s
\bse
\bel
\ble
\bec
\bct
\bt command, or arithmetic f
\bfo
\bor
\br command, dis-
5043 play the expanded value of P
\bPS
\bS4
\b4, followed by the command
5044 and its expanded arguments or associated word list.
5045 -
\b-B
\bB The shell performs brace expansion (see B
\bBr
\bra
\bac
\bce
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn
5046 above). This is on by default.
5047 -
\b-C
\bC If set, b
\bba
\bas
\bsh
\bh does not overwrite an existing file with
5048 the >
\b>, >
\b>&
\b&, and <
\b<>
\b> redirection operators. This may be
5049 overridden when creating output files by using the redi-
5050 rection operator >
\b>|
\b| instead of >
\b>.
5051 -
\b-E
\bE If set, any trap on E
\bER
\bRR
\bR is inherited by shell functions,
5052 command substitutions, and commands executed in a sub-
5053 shell environment. The E
\bER
\bRR
\bR trap is normally not inher-
5055 -
\b-H
\bH Enable !
\b! style history substitution. This option is on
5056 by default when the shell is interactive.
5057 -
\b-P
\bP If set, the shell does not resolve symbolic links when
5058 executing commands such as c
\bcd
\bd that change the current
5059 working directory. It uses the physical directory
5060 structure instead. By default, b
\bba
\bas
\bsh
\bh follows the logical
5061 chain of directories when performing commands which
5062 change the current directory.
5063 -
\b-T
\bT If set, any traps on D
\bDE
\bEB
\bBU
\bUG
\bG and R
\bRE
\bET
\bTU
\bUR
\bRN
\bN are inherited by
5064 shell functions, command substitutions, and commands
5065 executed in a subshell environment. The D
\bDE
\bEB
\bBU
\bUG
\bG and
5066 R
\bRE
\bET
\bTU
\bUR
\bRN
\bN traps are normally not inherited in such cases.
5067 -
\b--
\b- If no arguments follow this option, then the positional
5068 parameters are unset. Otherwise, the positional parame-
5069 ters are set to the _
\ba_
\br_
\bgs, even if some of them begin
5071 -
\b- Signal the end of options, cause all remaining _
\ba_
\br_
\bgs to
5072 be assigned to the positional parameters. The -
\b-x
\bx and -
\b-v
\bv
5073 options are turned off. If there are no _
\ba_
\br_
\bgs, the posi-
5074 tional parameters remain unchanged.
5076 The options are off by default unless otherwise noted. Using +
5077 rather than - causes these options to be turned off. The
5078 options can also be specified as arguments to an invocation of
5079 the shell. The current set of options may be found in $
\b$-
\b-. The
5080 return status is always true unless an invalid option is encoun-
5083 s
\bsh
\bhi
\bif
\bft
\bt [_
\bn]
5084 The positional parameters from _
\bn+1 ... are renamed to $
\b$1
\b1 .
\b..
\b..
\b..
\b.
5085 Parameters represented by the numbers $
\b$#
\b# down to $
\b$#
\b#-_
\bn+1 are
5086 unset. _
\bn must be a non-negative number less than or equal to
5087 $
\b$#
\b#. If _
\bn is 0, no parameters are changed. If _
\bn is not given,
5088 it is assumed to be 1. If _
\bn is greater than $
\b$#
\b#, the positional
5089 parameters are not changed. The return status is greater than
5090 zero if _
\bn is greater than $
\b$#
\b# or less than zero; otherwise 0.
5092 s
\bsh
\bho
\bop
\bpt
\bt [-
\b-p
\bpq
\bqs
\bsu
\bu] [-
\b-o
\bo] [_
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be ...]
5093 Toggle the values of settings controlling optional shell behav-
5094 ior. The settings can be either those listed below, or, if the
5095 -
\b-o
\bo option is used, those available with the -
\b-o
\bo option to the s
\bse
\bet
\bt
5096 builtin command. With no options, or with the -
\b-p
\bp option, a list
5097 of all settable options is displayed, with an indication of
5098 whether or not each is set. The -
\b-p
\bp option causes output to be
5099 displayed in a form that may be reused as input. Other options
5100 have the following meanings:
5101 -
\b-s
\bs Enable (set) each _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be.
5102 -
\b-u
\bu Disable (unset) each _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be.
5103 -
\b-q
\bq Suppresses normal output (quiet mode); the return status
5104 indicates whether the _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be is set or unset. If multi-
5105 ple _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be arguments are given with -
\b-q
\bq, the return sta-
5106 tus is zero if all _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be_
\bs are enabled; non-zero other-
5108 -
\b-o
\bo Restricts the values of _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be to be those defined for
5109 the -
\b-o
\bo option to the s
\bse
\bet
\bt builtin.
5111 If either -
\b-s
\bs or -
\b-u
\bu is used with no _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be arguments, s
\bsh
\bho
\bop
\bpt
\bt
5112 shows only those options which are set or unset, respectively.
5113 Unless otherwise noted, the s
\bsh
\bho
\bop
\bpt
\bt options are disabled (unset)
5116 The return status when listing options is zero if all _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be_
\bs
5117 are enabled, non-zero otherwise. When setting or unsetting
5118 options, the return status is zero unless an _
\bo_
\bp_
\bt_
\bn_
\ba_
\bm_
\be is not a
5121 The list of s
\bsh
\bho
\bop
\bpt
\bt options is:
5123 a
\bau
\but
\bto
\boc
\bcd
\bd If set, a command name that is the name of a directory
5124 is executed as if it were the argument to the c
\bcd
\bd com-
5125 mand. This option is only used by interactive shells.
5126 c
\bcd
\bda
\bab
\bbl
\ble
\be_
\b_v
\bva
\bar
\brs
\bs
5127 If set, an argument to the c
\bcd
\bd builtin command that is
5128 not a directory is assumed to be the name of a variable
5129 whose value is the directory to change to.
5130 c
\bcd
\bds
\bsp
\bpe
\bel
\bll
\bl If set, minor errors in the spelling of a directory com-
5131 ponent in a c
\bcd
\bd command will be corrected. The errors
5132 checked for are transposed characters, a missing charac-
5133 ter, and one character too many. If a correction is
5134 found, the corrected filename is printed, and the com-
5135 mand proceeds. This option is only used by interactive
5137 c
\bch
\bhe
\bec
\bck
\bkh
\bha
\bas
\bsh
\bh
5138 If set, b
\bba
\bas
\bsh
\bh checks that a command found in the hash ta-
5139 ble exists before trying to execute it. If a hashed
5140 command no longer exists, a normal path search is per-
5142 c
\bch
\bhe
\bec
\bck
\bkj
\bjo
\bob
\bbs
\bs
5143 If set, b
\bba
\bas
\bsh
\bh lists the status of any stopped and running
5144 jobs before exiting an interactive shell. If any jobs
5145 are running, this causes the exit to be deferred until a
5146 second exit is attempted without an intervening command
5147 (see J
\bJO
\bOB
\bB C
\bCO
\bON
\bNT
\bTR
\bRO
\bOL
\bL above). The shell always postpones
5148 exiting if any jobs are stopped.
5149 c
\bch
\bhe
\bec
\bck
\bkw
\bwi
\bin
\bns
\bsi
\biz
\bze
\be
5150 If set, b
\bba
\bas
\bsh
\bh checks the window size after each command
5151 and, if necessary, updates the values of L
\bLI
\bIN
\bNE
\bES
\bS and C
\bCO
\bOL
\bL-
\b-
5153 c
\bcm
\bmd
\bdh
\bhi
\bis
\bst
\bt If set, b
\bba
\bas
\bsh
\bh attempts to save all lines of a multiple-
5154 line command in the same history entry. This allows
5155 easy re-editing of multi-line commands.
5156 c
\bco
\bom
\bmp
\bpa
\bat
\bt3
\b31
\b1
5157 If set, b
\bba
\bas
\bsh
\bh changes its behavior to that of version 3.1
5158 with respect to quoted arguments to the [
\b[[
\b[ conditional
5159 command's =
\b=~
\b~ operator and locale-specific string compar-
5160 ison when using the [
\b[[
\b[ conditional command's <
\b< and >
\b>
5161 operators. Bash versions prior to bash-4.1 use ASCII
5162 collation and _
\bs_
\bt_
\br_
\bc_
\bm_
\bp(3); bash-4.1 and later use the cur-
5163 rent locale's collation sequence and _
\bs_
\bt_
\br_
\bc_
\bo_
\bl_
\bl(3).
5164 c
\bco
\bom
\bmp
\bpa
\bat
\bt3
\b32
\b2
5165 If set, b
\bba
\bas
\bsh
\bh changes its behavior to that of version 3.2
5166 with respect to locale-specific string comparison when
5167 using the [
\b[[
\b[ conditional command's <
\b< and >
\b> operators
5168 (see previous item).
5169 c
\bco
\bom
\bmp
\bpa
\bat
\bt4
\b40
\b0
5170 If set, b
\bba
\bas
\bsh
\bh changes its behavior to that of version 4.0
5171 with respect to locale-specific string comparison when
5172 using the [
\b[[
\b[ conditional command's <
\b< and >
\b> operators
5173 (see description of c
\bco
\bom
\bmp
\bpa
\bat
\bt3
\b31
\b1) and the effect of inter-
5174 rupting a command list. Bash versions 4.0 and later
5175 interrupt the list as if the shell received the inter-
5176 rupt; previous versions continue with the next command
5178 c
\bco
\bom
\bmp
\bpa
\bat
\bt4
\b41
\b1
5179 If set, b
\bba
\bas
\bsh
\bh, when in _
\bp_
\bo_
\bs_
\bi_
\bx mode, treats a single quote
5180 in a double-quoted parameter expansion as a special
5181 character. The single quotes must match (an even num-
5182 ber) and the characters between the single quotes are
5183 considered quoted. This is the behavior of posix mode
5184 through version 4.1. The default bash behavior remains
5185 as in previous versions.
5186 c
\bco
\bom
\bmp
\bpa
\bat
\bt4
\b42
\b2
5187 If set, b
\bba
\bas
\bsh
\bh does not process the replacement string in
5188 the pattern substitution word expansion using quote
5190 c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be_
\b_f
\bfu
\bul
\bll
\blq
\bqu
\buo
\bot
\bte
\be
5191 If set, b
\bba
\bas
\bsh
\bh quotes all shell metacharacters in file-
5192 names and directory names when performing completion.
5193 If not set, b
\bba
\bas
\bsh
\bh removes metacharacters such as the dol-
5194 lar sign from the set of characters that will be quoted
5195 in completed filenames when these metacharacters appear
5196 in shell variable references in words to be completed.
5197 This means that dollar signs in variable names that
5198 expand to directories will not be quoted; however, any
5199 dollar signs appearing in filenames will not be quoted,
5200 either. This is active only when bash is using back-
5201 slashes to quote completed filenames. This variable is
5202 set by default, which is the default bash behavior in
5203 versions through 4.2.
5204 d
\bdi
\bir
\bre
\bex
\bxp
\bpa
\ban
\bnd
\bd
5205 If set, b
\bba
\bas
\bsh
\bh replaces directory names with the results
5206 of word expansion when performing filename completion.
5207 This changes the contents of the readline editing
5208 buffer. If not set, b
\bba
\bas
\bsh
\bh attempts to preserve what the
5210 d
\bdi
\bir
\brs
\bsp
\bpe
\bel
\bll
\bl
5211 If set, b
\bba
\bas
\bsh
\bh attempts spelling correction on directory
5212 names during word completion if the directory name ini-
5213 tially supplied does not exist.
5214 d
\bdo
\bot
\btg
\bgl
\blo
\bob
\bb If set, b
\bba
\bas
\bsh
\bh includes filenames beginning with a `.' in
5215 the results of pathname expansion.
5216 e
\bex
\bxe
\bec
\bcf
\bfa
\bai
\bil
\bl
5217 If set, a non-interactive shell will not exit if it can-
5218 not execute the file specified as an argument to the
5219 e
\bex
\bxe
\bec
\bc builtin command. An interactive shell does not
5220 exit if e
\bex
\bxe
\bec
\bc fails.
5221 e
\bex
\bxp
\bpa
\ban
\bnd
\bd_
\b_a
\bal
\bli
\bia
\bas
\bse
\bes
\bs
5222 If set, aliases are expanded as described above under
5223 A
\bAL
\bLI
\bIA
\bAS
\bSE
\bES
\bS. This option is enabled by default for interac-
5225 e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg
5226 If set, behavior intended for use by debuggers is
5228 1
\b1.
\b. The -
\b-F
\bF option to the d
\bde
\bec
\bcl
\bla
\bar
\bre
\be builtin displays the
5229 source file name and line number corresponding to
5230 each function name supplied as an argument.
5231 2
\b2.
\b. If the command run by the D
\bDE
\bEB
\bBU
\bUG
\bG trap returns a
5232 non-zero value, the next command is skipped and
5234 3
\b3.
\b. If the command run by the D
\bDE
\bEB
\bBU
\bUG
\bG trap returns a
5235 value of 2, and the shell is executing in a sub-
5236 routine (a shell function or a shell script exe-
5237 cuted by the .
\b. or s
\bso
\bou
\bur
\brc
\bce
\be builtins), a call to
5238 r
\bre
\bet
\btu
\bur
\brn
\bn is simulated.
5239 4
\b4.
\b. B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGC
\bC and B
\bBA
\bAS
\bSH
\bH_
\b_A
\bAR
\bRG
\bGV
\bV are updated as described
5240 in their descriptions above.
5241 5
\b5.
\b. Function tracing is enabled: command substitu-
5242 tion, shell functions, and subshells invoked with
5243 (
\b( _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd )
\b) inherit the D
\bDE
\bEB
\bBU
\bUG
\bG and R
\bRE
\bET
\bTU
\bUR
\bRN
\bN traps.
5244 6
\b6.
\b. Error tracing is enabled: command substitution,
5245 shell functions, and subshells invoked with (
\b(
5246 _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd )
\b) inherit the E
\bER
\bRR
\bR trap.
5247 e
\bex
\bxt
\btg
\bgl
\blo
\bob
\bb If set, the extended pattern matching features described
5248 above under P
\bPa
\bat
\bth
\bhn
\bna
\bam
\bme
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn are enabled.
5249 e
\bex
\bxt
\btq
\bqu
\buo
\bot
\bte
\be
5250 If set, $
\b$'_
\bs_
\bt_
\br_
\bi_
\bn_
\bg' and $
\b$"_
\bs_
\bt_
\br_
\bi_
\bn_
\bg" quoting is performed
5251 within $
\b${
\b{_
\bp_
\ba_
\br_
\ba_
\bm_
\be_
\bt_
\be_
\br}
\b} expansions enclosed in double
5252 quotes. This option is enabled by default.
5253 f
\bfa
\bai
\bil
\blg
\bgl
\blo
\bob
\bb
5254 If set, patterns which fail to match filenames during
5255 pathname expansion result in an expansion error.
5256 f
\bfo
\bor
\brc
\bce
\be_
\b_f
\bfi
\big
\bgn
\bno
\bor
\bre
\be
5257 If set, the suffixes specified by the F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE shell
5258 variable cause words to be ignored when performing word
5259 completion even if the ignored words are the only possi-
5260 ble completions. See S
\bSH
\bHE
\bEL
\bLL
\bL V
\bVA
\bAR
\bRI
\bIA
\bAB
\bBL
\bLE
\bES
\bS above for a
5261 description of F
\bFI
\bIG
\bGN
\bNO
\bOR
\bRE
\bE. This option is enabled by
5263 g
\bgl
\blo
\bob
\bba
\bas
\bsc
\bci
\bii
\bir
\bra
\ban
\bng
\bge
\bes
\bs
5264 If set, range expressions used in pattern matching
5265 bracket expressions (see P
\bPa
\bat
\btt
\bte
\ber
\brn
\bn M
\bMa
\bat
\btc
\bch
\bhi
\bin
\bng
\bg above) behave
5266 as if in the traditional C locale when performing com-
5267 parisons. That is, the current locale's collating
5268 sequence is not taken into account, so b
\bb will not col-
5269 late between A
\bA and B
\bB, and upper-case and lower-case
5270 ASCII characters will collate together.
5271 g
\bgl
\blo
\bob
\bbs
\bst
\bta
\bar
\br
5272 If set, the pattern *
\b**
\b* used in a pathname expansion con-
5273 text will match all files and zero or more directories
5274 and subdirectories. If the pattern is followed by a /
\b/,
5275 only directories and subdirectories match.
5276 g
\bgn
\bnu
\bu_
\b_e
\ber
\brr
\brf
\bfm
\bmt
\bt
5277 If set, shell error messages are written in the standard
5278 GNU error message format.
5279 h
\bhi
\bis
\bst
\bta
\bap
\bpp
\bpe
\ben
\bnd
\bd
5280 If set, the history list is appended to the file named
5281 by the value of the H
\bHI
\bIS
\bST
\bTF
\bFI
\bIL
\bLE
\bE variable when the shell
5282 exits, rather than overwriting the file.
5283 h
\bhi
\bis
\bst
\btr
\bre
\bee
\bed
\bdi
\bit
\bt
5284 If set, and r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used, a user is given the
5285 opportunity to re-edit a failed history substitution.
5286 h
\bhi
\bis
\bst
\btv
\bve
\ber
\bri
\bif
\bfy
\by
5287 If set, and r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used, the results of his-
5288 tory substitution are not immediately passed to the
5289 shell parser. Instead, the resulting line is loaded
5290 into the r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be editing buffer, allowing further modi-
5292 h
\bho
\bos
\bst
\btc
\bco
\bom
\bmp
\bpl
\ble
\bet
\bte
\be
5293 If set, and r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used, b
\bba
\bas
\bsh
\bh will attempt to
5294 perform hostname completion when a word containing a @
\b@
5295 is being completed (see C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bin
\bng
\bg under R
\bRE
\bEA
\bAD
\bDL
\bLI
\bIN
\bNE
\bE
5296 above). This is enabled by default.
5297 h
\bhu
\bup
\bpo
\bon
\bne
\bex
\bxi
\bit
\bt
5298 If set, b
\bba
\bas
\bsh
\bh will send S
\bSI
\bIG
\bGH
\bHU
\bUP
\bP to all jobs when an inter-
5299 active login shell exits.
5300 i
\bin
\bnt
\bte
\ber
\bra
\bac
\bct
\bti
\biv
\bve
\be_
\b_c
\bco
\bom
\bmm
\bme
\ben
\bnt
\bts
\bs
5301 If set, allow a word beginning with #
\b# to cause that word
5302 and all remaining characters on that line to be ignored
5303 in an interactive shell (see C
\bCO
\bOM
\bMM
\bME
\bEN
\bNT
\bTS
\bS above). This
5304 option is enabled by default.
5305 l
\bla
\bas
\bst
\btp
\bpi
\bip
\bpe
\be
5306 If set, and job control is not active, the shell runs
5307 the last command of a pipeline not executed in the back-
5308 ground in the current shell environment.
5309 l
\bli
\bit
\bth
\bhi
\bis
\bst
\bt If set, and the c
\bcm
\bmd
\bdh
\bhi
\bis
\bst
\bt option is enabled, multi-line
5310 commands are saved to the history with embedded newlines
5311 rather than using semicolon separators where possible.
5312 l
\blo
\bog
\bgi
\bin
\bn_
\b_s
\bsh
\bhe
\bel
\bll
\bl
5313 The shell sets this option if it is started as a login
5314 shell (see I
\bIN
\bNV
\bVO
\bOC
\bCA
\bAT
\bTI
\bIO
\bON
\bN above). The value may not be
5316 m
\bma
\bai
\bil
\blw
\bwa
\bar
\brn
\bn
5317 If set, and a file that b
\bba
\bas
\bsh
\bh is checking for mail has
5318 been accessed since the last time it was checked, the
5319 message ``The mail in _
\bm_
\ba_
\bi_
\bl_
\bf_
\bi_
\bl_
\be has been read'' is dis-
5321 n
\bno
\bo_
\b_e
\bem
\bmp
\bpt
\bty
\by_
\b_c
\bcm
\bmd
\bd_
\b_c
\bco
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn
5322 If set, and r
\bre
\bea
\bad
\bdl
\bli
\bin
\bne
\be is being used, b
\bba
\bas
\bsh
\bh will not
5323 attempt to search the P
\bPA
\bAT
\bTH
\bH for possible completions when
5324 completion is attempted on an empty line.
5325 n
\bno
\boc
\bca
\bas
\bse
\beg
\bgl
\blo
\bob
\bb
5326 If set, b
\bba
\bas
\bsh
\bh matches filenames in a case-insensitive
5327 fashion when performing pathname expansion (see P
\bPa
\bat
\bth
\bhn
\bna
\bam
\bme
\be
5328 E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn above).
5329 n
\bno
\boc
\bca
\bas
\bse
\bem
\bma
\bat
\btc
\bch
\bh
5330 If set, b
\bba
\bas
\bsh
\bh matches patterns in a case-insensitive
5331 fashion when performing matching while executing c
\bca
\bas
\bse
\be or
5332 [
\b[[
\b[ conditional commands.
5333 n
\bnu
\bul
\bll
\blg
\bgl
\blo
\bob
\bb
5334 If set, b
\bba
\bas
\bsh
\bh allows patterns which match no files (see
5335 P
\bPa
\bat
\bth
\bhn
\bna
\bam
\bme
\be E
\bEx
\bxp
\bpa
\ban
\bns
\bsi
\bio
\bon
\bn above) to expand to a null string,
5336 rather than themselves.
5337 p
\bpr
\bro
\bog
\bgc
\bco
\bom
\bmp
\bp
5338 If set, the programmable completion facilities (see P
\bPr
\bro
\bo-
\b-
5339 g
\bgr
\bra
\bam
\bmm
\bma
\bab
\bbl
\ble
\be C
\bCo
\bom
\bmp
\bpl
\ble
\bet
\bti
\bio
\bon
\bn above) are enabled. This option is
5341 p
\bpr
\bro
\bom
\bmp
\bpt
\btv
\bva
\bar
\brs
\bs
5342 If set, prompt strings undergo parameter expansion, com-
5343 mand substitution, arithmetic expansion, and quote
5344 removal after being expanded as described in P
\bPR
\bRO
\bOM
\bMP
\bPT
\bTI
\bIN
\bNG
\bG
5345 above. This option is enabled by default.
5346 r
\bre
\bes
\bst
\btr
\bri
\bic
\bct
\bte
\bed
\bd_
\b_s
\bsh
\bhe
\bel
\bll
\bl
5347 The shell sets this option if it is started in
5348 restricted mode (see R
\bRE
\bES
\bST
\bTR
\bRI
\bIC
\bCT
\bTE
\bED
\bD S
\bSH
\bHE
\bEL
\bLL
\bL below). The value
5349 may not be changed. This is not reset when the startup
5350 files are executed, allowing the startup files to dis-
5351 cover whether or not a shell is restricted.
5352 s
\bsh
\bhi
\bif
\bft
\bt_
\b_v
\bve
\ber
\brb
\bbo
\bos
\bse
\be
5353 If set, the s
\bsh
\bhi
\bif
\bft
\bt builtin prints an error message when
5354 the shift count exceeds the number of positional parame-
5356 s
\bso
\bou
\bur
\brc
\bce
\bep
\bpa
\bat
\bth
\bh
5357 If set, the s
\bso
\bou
\bur
\brc
\bce
\be (.
\b.) builtin uses the value of P
\bPA
\bAT
\bTH
\bH to
5358 find the directory containing the file supplied as an
5359 argument. This option is enabled by default.
5360 x
\bxp
\bpg
\bg_
\b_e
\bec
\bch
\bho
\bo
5361 If set, the e
\bec
\bch
\bho
\bo builtin expands backslash-escape
5362 sequences by default.
5364 s
\bsu
\bus
\bsp
\bpe
\ben
\bnd
\bd [-
\b-f
\bf]
5365 Suspend the execution of this shell until it receives a S
\bSI
\bIG
\bGC
\bCO
\bON
\bNT
\bT
5366 signal. A login shell cannot be suspended; the -
\b-f
\bf option can be
5367 used to override this and force the suspension. The return sta-
5368 tus is 0 unless the shell is a login shell and -
\b-f
\bf is not sup-
5369 plied, or if job control is not enabled.
5371 t
\bte
\bes
\bst
\bt _
\be_
\bx_
\bp_
\br
5372 [
\b[ _
\be_
\bx_
\bp_
\br ]
\b]
5373 Return a status of 0 (true) or 1 (false) depending on the evalu-
5374 ation of the conditional expression _
\be_
\bx_
\bp_
\br. Each operator and op-
5375 erand must be a separate argument. Expressions are composed of
5376 the primaries described above under C
\bCO
\bON
\bND
\bDI
\bIT
\bTI
\bIO
\bON
\bNA
\bAL
\bL E
\bEX
\bXP
\bPR
\bRE
\bES
\bSS
\bSI
\bIO
\bON
\bNS
\bS.
5377 t
\bte
\bes
\bst
\bt does not accept any options, nor does it accept and ignore
5378 an argument of -
\b--
\b- as signifying the end of options.
5380 Expressions may be combined using the following operators,
5381 listed in decreasing order of precedence. The evaluation
5382 depends on the number of arguments; see below. Operator prece-
5383 dence is used when there are five or more arguments.
5384 !
\b! _
\be_
\bx_
\bp_
\br True if _
\be_
\bx_
\bp_
\br is false.
5385 (
\b( _
\be_
\bx_
\bp_
\br )
\b)
5386 Returns the value of _
\be_
\bx_
\bp_
\br. This may be used to override
5387 the normal precedence of operators.
5388 _
\be_
\bx_
\bp_
\br_
\b1 -a
\ba _
\be_
\bx_
\bp_
\br_
\b2
5389 True if both _
\be_
\bx_
\bp_
\br_
\b1 and _
\be_
\bx_
\bp_
\br_
\b2 are true.
5390 _
\be_
\bx_
\bp_
\br_
\b1 -o
\bo _
\be_
\bx_
\bp_
\br_
\b2
5391 True if either _
\be_
\bx_
\bp_
\br_
\b1 or _
\be_
\bx_
\bp_
\br_
\b2 is true.
5393 t
\bte
\bes
\bst
\bt and [
\b[ evaluate conditional expressions using a set of rules
5394 based on the number of arguments.
5397 The expression is false.
5399 The expression is true if and only if the argument is not
5402 If the first argument is !
\b!, the expression is true if and
5403 only if the second argument is null. If the first argu-
5404 ment is one of the unary conditional operators listed
5405 above under C
\bCO
\bON
\bND
\bDI
\bIT
\bTI
\bIO
\bON
\bNA
\bAL
\bL E
\bEX
\bXP
\bPR
\bRE
\bES
\bSS
\bSI
\bIO
\bON
\bNS
\bS, the expression is
5406 true if the unary test is true. If the first argument is
5407 not a valid unary conditional operator, the expression is
5410 The following conditions are applied in the order listed.
5411 If the second argument is one of the binary conditional
5412 operators listed above under C
\bCO
\bON
\bND
\bDI
\bIT
\bTI
\bIO
\bON
\bNA
\bAL
\bL E
\bEX
\bXP
\bPR
\bRE
\bES
\bSS
\bSI
\bIO
\bON
\bNS
\bS, the
5413 result of the expression is the result of the binary test
5414 using the first and third arguments as operands. The -
\b-a
\ba
5415 and -
\b-o
\bo operators are considered binary operators when
5416 there are three arguments. If the first argument is !
\b!,
5417 the value is the negation of the two-argument test using
5418 the second and third arguments. If the first argument is
5419 exactly (
\b( and the third argument is exactly )
\b), the result
5420 is the one-argument test of the second argument. Other-
5421 wise, the expression is false.
5423 If the first argument is !
\b!, the result is the negation of
5424 the three-argument expression composed of the remaining
5425 arguments. Otherwise, the expression is parsed and eval-
5426 uated according to precedence using the rules listed
5429 The expression is parsed and evaluated according to
5430 precedence using the rules listed above.
5432 When used with t
\bte
\bes
\bst
\bt or [
\b[, the <
\b< and >
\b> operators sort lexico-
5433 graphically using ASCII ordering.
5435 t
\bti
\bim
\bme
\bes
\bs Print the accumulated user and system times for the shell and
5436 for processes run from the shell. The return status is 0.
5438 t
\btr
\bra
\bap
\bp [-
\b-l
\blp
\bp] [[_
\ba_
\br_
\bg] _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc ...]
5439 The command _
\ba_
\br_
\bg is to be read and executed when the shell
5440 receives signal(s) _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc. If _
\ba_
\br_
\bg is absent (and there is a
5441 single _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc) or -
\b-, each specified signal is reset to its
5442 original disposition (the value it had upon entrance to the
5443 shell). If _
\ba_
\br_
\bg is the null string the signal specified by each
5444 _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is ignored by the shell and by the commands it invokes.
5445 If _
\ba_
\br_
\bg is not present and -
\b-p
\bp has been supplied, then the trap
5446 commands associated with each _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc are displayed. If no
5447 arguments are supplied or if only -
\b-p
\bp is given, t
\btr
\bra
\bap
\bp prints the
5448 list of commands associated with each signal. The -
\b-l
\bl option
5449 causes the shell to print a list of signal names and their cor-
5450 responding numbers. Each _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is either a signal name
5451 defined in <_
\bs_
\bi_
\bg_
\bn_
\ba_
\bl_
\b._
\bh>, or a signal number. Signal names are
5452 case insensitive and the S
\bSI
\bIG
\bG prefix is optional.
5454 If a _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is E
\bEX
\bXI
\bIT
\bT (0) the command _
\ba_
\br_
\bg is executed on exit
5455 from the shell. If a _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is D
\bDE
\bEB
\bBU
\bUG
\bG, the command _
\ba_
\br_
\bg is exe-
5456 cuted before every _
\bs_
\bi_
\bm_
\bp_
\bl_
\be _
\bc_
\bo_
\bm_
\bm_
\ba_
\bn_
\bd, _
\bf_
\bo_
\br command, _
\bc_
\ba_
\bs_
\be command,
5457 _
\bs_
\be_
\bl_
\be_
\bc_
\bt command, every arithmetic _
\bf_
\bo_
\br command, and before the
5458 first command executes in a shell function (see S
\bSH
\bHE
\bEL
\bLL
\bL G
\bGR
\bRA
\bAM
\bMM
\bMA
\bAR
\bR
5459 above). Refer to the description of the e
\bex
\bxt
\btd
\bde
\beb
\bbu
\bug
\bg option to the
5460 s
\bsh
\bho
\bop
\bpt
\bt builtin for details of its effect on the D
\bDE
\bEB
\bBU
\bUG
\bG trap. If a
5461 _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is R
\bRE
\bET
\bTU
\bUR
\bRN
\bN, the command _
\ba_
\br_
\bg is executed each time a shell
5462 function or a script executed with the .
\b. or s
\bso
\bou
\bur
\brc
\bce
\be builtins fin-
5465 If a _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is E
\bER
\bRR
\bR, the command _
\ba_
\br_
\bg is executed whenever a a
5466 pipeline (which may consist of a single simple command), a list,
5467 or a compound command returns a non-zero exit status, subject to
5468 the following conditions. The E
\bER
\bRR
\bR trap is not executed if the
5469 failed command is part of the command list immediately following
5470 a w
\bwh
\bhi
\bil
\ble
\be or u
\bun
\bnt
\bti
\bil
\bl keyword, part of the test in an _
\bi_
\bf statement,
5471 part of a command executed in a &
\b&&
\b& or |
\b||
\b| list except the command
5472 following the final &
\b&&
\b& or |
\b||
\b|, any command in a pipeline but the
5473 last, or if the command's return value is being inverted using
5474 !
\b!. These are the same conditions obeyed by the e
\ber
\brr
\bre
\bex
\bxi
\bit
\bt (-
\b-e
\be)
5477 Signals ignored upon entry to the shell cannot be trapped or
5478 reset. Trapped signals that are not being ignored are reset to
5479 their original values in a subshell or subshell environment when
5480 one is created. The return status is false if any _
\bs_
\bi_
\bg_
\bs_
\bp_
\be_
\bc is
5481 invalid; otherwise t
\btr
\bra
\bap
\bp returns true.
5483 t
\bty
\byp
\bpe
\be [-
\b-a
\baf
\bft
\btp
\bpP
\bP] _
\bn_
\ba_
\bm_
\be [_
\bn_
\ba_
\bm_
\be ...]
5484 With no options, indicate how each _
\bn_
\ba_
\bm_
\be would be interpreted if
5485 used as a command name. If the -
\b-t
\bt option is used, t
\bty
\byp
\bpe
\be prints a
5486 string which is one of _
\ba_
\bl_
\bi_
\ba_
\bs, _
\bk_
\be_
\by_
\bw_
\bo_
\br_
\bd, _
\bf_
\bu_
\bn_
\bc_
\bt_
\bi_
\bo_
\bn, _
\bb_
\bu_
\bi_
\bl_
\bt_
\bi_
\bn, or
5487 _
\bf_
\bi_
\bl_
\be if _
\bn_
\ba_
\bm_
\be is an alias, shell reserved word, function,
5488 builtin, or disk file, respectively. If the _
\bn_
\ba_
\bm_
\be is not found,
5489 then nothing is printed, and an exit status of false is
5490 returned. If the -
\b-p
\bp option is used, t
\bty
\byp
\bpe
\be either returns the
5491 name of the disk file that would be executed if _
\bn_
\ba_
\bm_
\be were speci-
5492 fied as a command name, or nothing if ``type -t name'' would not
5493 return _
\bf_
\bi_
\bl_
\be. The -
\b-P
\bP option forces a P
\bPA
\bAT
\bTH
\bH search for each _
\bn_
\ba_
\bm_
\be,
5494 even if ``type -t name'' would not return _
\bf_
\bi_
\bl_
\be. If a command is
5495 hashed, -
\b-p
\bp and -
\b-P
\bP print the hashed value, which is not necessar-
5496 ily the file that appears first in P
\bPA
\bAT
\bTH
\bH. If the -
\b-a
\ba option is
5497 used, t
\bty
\byp
\bpe
\be prints all of the places that contain an executable
5498 named _
\bn_
\ba_
\bm_
\be. This includes aliases and functions, if and only if
5499 the -
\b-p
\bp option is not also used. The table of hashed commands is
5500 not consulted when using -
\b-a
\ba. The -
\b-f
\bf option suppresses shell
5501 function lookup, as with the c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd builtin. t
\bty
\byp
\bpe
\be returns true
5502 if all of the arguments are found, false if any are not found.
5504 u
\bul
\bli
\bim
\bmi
\bit
\bt [-
\b-H
\bHS
\bST
\bTa
\bab
\bbc
\bcd
\bde
\bef
\bfi
\bil
\blm
\bmn
\bnp
\bpq
\bqr
\brs
\bst
\btu
\buv
\bvx
\bx [_
\bl_
\bi_
\bm_
\bi_
\bt]]
5505 Provides control over the resources available to the shell and
5506 to processes started by it, on systems that allow such control.
5507 The -
\b-H
\bH and -
\b-S
\bS options specify that the hard or soft limit is set
5508 for the given resource. A hard limit cannot be increased by a
5509 non-root user once it is set; a soft limit may be increased up
5510 to the value of the hard limit. If neither -
\b-H
\bH nor -
\b-S
\bS is speci-
5511 fied, both the soft and hard limits are set. The value of _
\bl_
\bi_
\bm_
\bi_
\bt
5512 can be a number in the unit specified for the resource or one of
5513 the special values h
\bha
\bar
\brd
\bd, s
\bso
\bof
\bft
\bt, or u
\bun
\bnl
\bli
\bim
\bmi
\bit
\bte
\bed
\bd, which stand for the
5514 current hard limit, the current soft limit, and no limit,
5515 respectively. If _
\bl_
\bi_
\bm_
\bi_
\bt is omitted, the current value of the
5516 soft limit of the resource is printed, unless the -
\b-H
\bH option is
5517 given. When more than one resource is specified, the limit name
5518 and unit are printed before the value. Other options are inter-
5520 -
\b-a
\ba All current limits are reported
5521 -
\b-b
\bb The maximum socket buffer size
5522 -
\b-c
\bc The maximum size of core files created
5523 -
\b-d
\bd The maximum size of a process's data segment
5524 -
\b-e
\be The maximum scheduling priority ("nice")
5525 -
\b-f
\bf The maximum size of files written by the shell and its
5527 -
\b-i
\bi The maximum number of pending signals
5528 -
\b-l
\bl The maximum size that may be locked into memory
5529 -
\b-m
\bm The maximum resident set size (many systems do not honor
5531 -
\b-n
\bn The maximum number of open file descriptors (most systems
5532 do not allow this value to be set)
5533 -
\b-p
\bp The pipe size in 512-byte blocks (this may not be set)
5534 -
\b-q
\bq The maximum number of bytes in POSIX message queues
5535 -
\b-r
\br The maximum real-time scheduling priority
5536 -
\b-s
\bs The maximum stack size
5537 -
\b-t
\bt The maximum amount of cpu time in seconds
5538 -
\b-u
\bu The maximum number of processes available to a single
5540 -
\b-v
\bv The maximum amount of virtual memory available to the
5541 shell and, on some systems, to its children
5542 -
\b-x
\bx The maximum number of file locks
5543 -
\b-T
\bT The maximum number of threads
5545 If _
\bl_
\bi_
\bm_
\bi_
\bt is given, and the -
\b-a
\ba option is not used, _
\bl_
\bi_
\bm_
\bi_
\bt is the
5546 new value of the specified resource. If no option is given,
5547 then -
\b-f
\bf is assumed. Values are in 1024-byte increments, except
5548 for -
\b-t
\bt, which is in seconds; -
\b-p
\bp, which is in units of 512-byte
5549 blocks; and -
\b-T
\bT, -
\b-b
\bb, -
\b-n
\bn, and -
\b-u
\bu, which are unscaled values. The
5550 return status is 0 unless an invalid option or argument is sup-
5551 plied, or an error occurs while setting a new limit.
5553 u
\bum
\bma
\bas
\bsk
\bk [-
\b-p
\bp] [-
\b-S
\bS] [_
\bm_
\bo_
\bd_
\be]
5554 The user file-creation mask is set to _
\bm_
\bo_
\bd_
\be. If _
\bm_
\bo_
\bd_
\be begins with
5555 a digit, it is interpreted as an octal number; otherwise it is
5556 interpreted as a symbolic mode mask similar to that accepted by
5557 _
\bc_
\bh_
\bm_
\bo_
\bd(1). If _
\bm_
\bo_
\bd_
\be is omitted, the current value of the mask is
5558 printed. The -
\b-S
\bS option causes the mask to be printed in sym-
5559 bolic form; the default output is an octal number. If the -
\b-p
\bp
5560 option is supplied, and _
\bm_
\bo_
\bd_
\be is omitted, the output is in a form
5561 that may be reused as input. The return status is 0 if the mode
5562 was successfully changed or if no _
\bm_
\bo_
\bd_
\be argument was supplied,
5563 and false otherwise.
5565 u
\bun
\bna
\bal
\bli
\bia
\bas
\bs [-a
\ba] [_
\bn_
\ba_
\bm_
\be ...]
5566 Remove each _
\bn_
\ba_
\bm_
\be from the list of defined aliases. If -
\b-a
\ba is
5567 supplied, all alias definitions are removed. The return value
5568 is true unless a supplied _
\bn_
\ba_
\bm_
\be is not a defined alias.
5570 u
\bun
\bns
\bse
\bet
\bt [-f
\bfv
\bv] [-n
\bn] [_
\bn_
\ba_
\bm_
\be ...]
5571 For each _
\bn_
\ba_
\bm_
\be, remove the corresponding variable or function.
5572 If the -
\b-v
\bv option is given, each _
\bn_
\ba_
\bm_
\be refers to a shell variable,
5573 and that variable is removed. Read-only variables may not be
5574 unset. If -
\b-f
\bf is specified, each _
\bn_
\ba_
\bm_
\be refers to a shell func-
5575 tion, and the function definition is removed. If the -
\b-n
\bn option
5576 is supplied, and _
\bn_
\ba_
\bm_
\be is a variable with the _
\bn_
\ba_
\bm_
\be_
\br_
\be_
\bf attribute,
5577 _
\bn_
\ba_
\bm_
\be will be unset rather than the variable it references. -
\b-n
\bn
5578 has no effect if the -
\b-f
\bf option is supplied. If no options are
5579 supplied, each _
\bn_
\ba_
\bm_
\be refers to a variable; if there is no vari-
5580 able by that name, any function with that name is unset. Each
5581 unset variable or function is removed from the environment
5582 passed to subsequent commands. If any of C
\bCO
\bOM
\bMP
\bP_
\b_W
\bWO
\bOR
\bRD
\bDB
\bBR
\bRE
\bEA
\bAK
\bKS
\bS, R
\bRA
\bAN
\bN-
\b-
5583 D
\bDO
\bOM
\bM, S
\bSE
\bEC
\bCO
\bON
\bND
\bDS
\bS, L
\bLI
\bIN
\bNE
\bEN
\bNO
\bO, H
\bHI
\bIS
\bST
\bTC
\bCM
\bMD
\bD, F
\bFU
\bUN
\bNC
\bCN
\bNA
\bAM
\bME
\bE, G
\bGR
\bRO
\bOU
\bUP
\bPS
\bS, or D
\bDI
\bIR
\bRS
\bST
\bTA
\bAC
\bCK
\bK are
5584 unset, they lose their special properties, even if they are sub-
5585 sequently reset. The exit status is true unless a _
\bn_
\ba_
\bm_
\be is read-
5588 w
\bwa
\bai
\bit
\bt [-
\b-n
\bn] [_
\bn _
\b._
\b._
\b.]
5589 Wait for each specified child process and return its termination
5590 status. Each _
\bn may be a process ID or a job specification; if a
5591 job spec is given, all processes in that job's pipeline are
5592 waited for. If _
\bn is not given, all currently active child pro-
5593 cesses are waited for, and the return status is zero. If the -
\b-n
\bn
5594 option is supplied, w
\bwa
\bai
\bit
\bt waits for any job to terminate and
5595 returns its exit status. If _
\bn specifies a non-existent process
5596 or job, the return status is 127. Otherwise, the return status
5597 is the exit status of the last process or job waited for.
5599 R
\bRE
\bES
\bST
\bTR
\bRI
\bIC
\bCT
\bTE
\bED
\bD S
\bSH
\bHE
\bEL
\bLL
\bL
5600 If b
\bba
\bas
\bsh
\bh is started with the name r
\brb
\bba
\bas
\bsh
\bh, or the -
\b-r
\br option is supplied at
5601 invocation, the shell becomes restricted. A restricted shell is used
5602 to set up an environment more controlled than the standard shell. It
5603 behaves identically to b
\bba
\bas
\bsh
\bh with the exception that the following are
5604 disallowed or not performed:
5606 +
\bo changing directories with c
\bcd
\bd
5608 +
\bo setting or unsetting the values of S
\bSH
\bHE
\bEL
\bLL
\bL, P
\bPA
\bAT
\bTH
\bH, E
\bEN
\bNV
\bV, or B
\bBA
\bAS
\bSH
\bH_
\b_E
\bEN
\bNV
\bV
5610 +
\bo specifying command names containing /
\b/
5612 +
\bo specifying a filename containing a /
\b/ as an argument to the .
\b.
5615 +
\bo specifying a filename containing a slash as an argument to the
5616 -
\b-p
\bp option to the h
\bha
\bas
\bsh
\bh builtin command
5618 +
\bo importing function definitions from the shell environment at
5621 +
\bo parsing the value of S
\bSH
\bHE
\bEL
\bLL
\bLO
\bOP
\bPT
\bTS
\bS from the shell environment at
5624 +
\bo redirecting output using the >, >|, <>, >&, &>, and >> redirect-
5627 +
\bo using the e
\bex
\bxe
\bec
\bc builtin command to replace the shell with another
5630 +
\bo adding or deleting builtin commands with the -
\b-f
\bf and -
\b-d
\bd options
5631 to the e
\ben
\bna
\bab
\bbl
\ble
\be builtin command
5633 +
\bo using the e
\ben
\bna
\bab
\bbl
\ble
\be builtin command to enable disabled shell
5636 +
\bo specifying the -
\b-p
\bp option to the c
\bco
\bom
\bmm
\bma
\ban
\bnd
\bd builtin command
5638 +
\bo turning off restricted mode with s
\bse
\bet
\bt +
\b+r
\br or s
\bse
\bet
\bt +
\b+o
\bo r
\bre
\bes
\bst
\btr
\bri
\bic
\bct
\bte
\bed
\bd.
5640 These restrictions are enforced after any startup files are read.
5642 When a command that is found to be a shell script is executed (see C
\bCO
\bOM
\bM-
\b-
5643 M
\bMA
\bAN
\bND
\bD E
\bEX
\bXE
\bEC
\bCU
\bUT
\bTI
\bIO
\bON
\bN above), r
\brb
\bba
\bas
\bsh
\bh turns off any restrictions in the shell
5644 spawned to execute the script.
5646 S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
5647 _
\bB_
\ba_
\bs_
\bh _
\bR_
\be_
\bf_
\be_
\br_
\be_
\bn_
\bc_
\be _
\bM_
\ba_
\bn_
\bu_
\ba_
\bl, Brian Fox and Chet Ramey
5648 _
\bT_
\bh_
\be _
\bG_
\bn_
\bu _
\bR_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be _
\bL_
\bi_
\bb_
\br_
\ba_
\br_
\by, Brian Fox and Chet Ramey
5649 _
\bT_
\bh_
\be _
\bG_
\bn_
\bu _
\bH_
\bi_
\bs_
\bt_
\bo_
\br_
\by _
\bL_
\bi_
\bb_
\br_
\ba_
\br_
\by, Brian Fox and Chet Ramey
5650 _
\bP_
\bo_
\br_
\bt_
\ba_
\bb_
\bl_
\be _
\bO_
\bp_
\be_
\br_
\ba_
\bt_
\bi_
\bn_
\bg _
\bS_
\by_
\bs_
\bt_
\be_
\bm _
\bI_
\bn_
\bt_
\be_
\br_
\bf_
\ba_
\bc_
\be _
\b(_
\bP_
\bO_
\bS_
\bI_
\bX_
\b) _
\bP_
\ba_
\br_
\bt _
\b2_
\b: _
\bS_
\bh_
\be_
\bl_
\bl _
\ba_
\bn_
\bd _
\bU_
\bt_
\bi_
\bl_
\bi_
\b-
5651 _
\bt_
\bi_
\be_
\bs, IEEE --
5652 http://pubs.opengroup.org/onlinepubs/9699919799/
5653 http://tiswww.case.edu/~chet/bash/POSIX -- a description of posix mode
5654 _
\bs_
\bh(1), _
\bk_
\bs_
\bh(1), _
\bc_
\bs_
\bh(1)
5655 _
\be_
\bm_
\ba_
\bc_
\bs(1), _
\bv_
\bi(1)
5656 _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be(3)
5658 F
\bFI
\bIL
\bLE
\bES
\bS
5659 _
\b/_
\bb_
\bi_
\bn_
\b/_
\bb_
\ba_
\bs_
\bh
5660 The b
\bba
\bas
\bsh
\bh executable
5661 _
\b/_
\be_
\bt_
\bc_
\b/_
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be
5662 The systemwide initialization file, executed for login shells
5663 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bp_
\br_
\bo_
\bf_
\bi_
\bl_
\be
5664 The personal initialization file, executed for login shells
5665 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\br_
\bc
5666 The individual per-interactive-shell startup file
5667 _
\b~_
\b/_
\b._
\bb_
\ba_
\bs_
\bh_
\b__
\bl_
\bo_
\bg_
\bo_
\bu_
\bt
5668 The individual login shell cleanup file, executed when a login
5670 _
\b~_
\b/_
\b._
\bi_
\bn_
\bp_
\bu_
\bt_
\br_
\bc
5671 Individual _
\br_
\be_
\ba_
\bd_
\bl_
\bi_
\bn_
\be initialization file
5673 A
\bAU
\bUT
\bTH
\bHO
\bOR
\bRS
\bS
5674 Brian Fox, Free Software Foundation
5677 Chet Ramey, Case Western Reserve University
5680 B
\bBU
\bUG
\bG R
\bRE
\bEP
\bPO
\bOR
\bRT
\bTS
\bS
5681 If you find a bug in b
\bba
\bas
\bsh
\bh,
\b, you should report it. But first, you should
5682 make sure that it really is a bug, and that it appears in the latest
5683 version of b
\bba
\bas
\bsh
\bh. The latest version is always available from
5684 _
\bf_
\bt_
\bp_
\b:_
\b/_
\b/_
\bf_
\bt_
\bp_
\b._
\bg_
\bn_
\bu_
\b._
\bo_
\br_
\bg_
\b/_
\bp_
\bu_
\bb_
\b/_
\bg_
\bn_
\bu_
\b/_
\bb_
\ba_
\bs_
\bh_
\b/.
5686 Once you have determined that a bug actually exists, use the _
\bb_
\ba_
\bs_
\bh_
\bb_
\bu_
\bg
5687 command to submit a bug report. If you have a fix, you are encouraged
5688 to mail that as well! Suggestions and `philosophical' bug reports may
5689 be mailed to _
\bb_
\bu_
\bg_
\b-_
\bb_
\ba_
\bs_
\bh_
\b@_
\bg_
\bn_
\bu_
\b._
\bo_
\br_
\bg or posted to the Usenet newsgroup
5690 g
\bgn
\bnu
\bu.
\b.b
\bba
\bas
\bsh
\bh.
\b.b
\bbu
\bug
\bg.
5692 ALL bug reports should include:
5694 The version number of b
\bba
\bas
\bsh
\bh
5695 The hardware and operating system
5696 The compiler used to compile
5697 A description of the bug behaviour
5698 A short script or `recipe' which exercises the bug
5700 _
\bb_
\ba_
\bs_
\bh_
\bb_
\bu_
\bg inserts the first three items automatically into the template
5701 it provides for filing a bug report.
5703 Comments and bug reports concerning this manual page should be directed
5704 to _
\bc_
\bh_
\be_
\bt_
\b._
\br_
\ba_
\bm_
\be_
\by_
\b@_
\bc_
\ba_
\bs_
\be_
\b._
\be_
\bd_
\bu.
5707 It's too big and too slow.
5709 There are some subtle differences between b
\bba
\bas
\bsh
\bh and traditional versions
5710 of s
\bsh
\bh, mostly because of the P
\bPO
\bOS
\bSI
\bIX
\bX specification.
5712 Aliases are confusing in some uses.
5714 Shell builtin commands and functions are not stoppable/restartable.
5716 Compound commands and command sequences of the form `a ; b ; c' are not
5717 handled gracefully when process suspension is attempted. When a
5718 process is stopped, the shell immediately executes the next command in
5719 the sequence. It suffices to place the sequence of commands between
5720 parentheses to force it into a subshell, which may be stopped as a
5723 Array variables may not (yet) be exported.
5725 There may be only one active coprocess at a time.
5729 GNU Bash 4.3 2014 February 2 BASH(1)