mirror of
https://https.git.savannah.gnu.org/git/bash.git
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change to behavior of '&' in pattern substitution replacement string; fix for blank lines in multiline commands saved in command history
This commit is contained in:
Chet Ramey
+30
-20
@@ -9,7 +9,7 @@ SSYYNNOOPPSSIISS
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bbaasshh [options] [command_string | file]
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CCOOPPYYRRIIGGHHTT
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Bash is Copyright (C) 1989-2021 by the Free Software Foundation, Inc.
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Bash is Copyright (C) 1989-2022 by the Free Software Foundation, Inc.
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DDEESSCCRRIIPPTTIIOONN
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BBaasshh is an sshh-compatible command language interpreter that executes
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@@ -1849,24 +1849,34 @@ EEXXPPAANNSSIIOONN
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end of the expanded value of _p_a_r_a_m_e_t_e_r. If the expansion of
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_s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are deleted. If _s_t_r_i_n_g is
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null, matches of _p_a_t_t_e_r_n are deleted and the // following _p_a_t_t_e_r_n
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may be omitted. If the ppaattssuubb__rreeppllaacceemmeenntt shell option is en-
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abled using sshhoopptt, any unquoted instances of && in _s_t_r_i_n_g are re-
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placed with the matching portion of _p_a_t_t_e_r_n. Backslash is used
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to quote && in _s_t_r_i_n_g; the backslash is removed in order to per-
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mit a literal && in the replacement string. Users should take
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care if _s_t_r_i_n_g is double-quoted to avoid unwanted interactions
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between the backslash and double-quoting. Pattern substitution
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performs the check for && after expanding _s_t_r_i_n_g; shell program-
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mers should quote backslashes intended to escape the && and in-
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hibit replacement so they survive any quote removal performed by
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the expansion of _s_t_r_i_n_g. If the nnooccaasseemmaattcchh shell option is en-
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abled, the match is performed without regard to the case of al-
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phabetic characters. If _p_a_r_a_m_e_t_e_r is @@ or **, the substitution
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operation is applied to each positional parameter in turn, and
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the expansion is the resultant list. If _p_a_r_a_m_e_t_e_r is an array
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variable subscripted with @@ or **, the substitution operation is
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applied to each member of the array in turn, and the expansion
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is the resultant list.
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may be omitted.
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If the ppaattssuubb__rreeppllaacceemmeenntt shell option is enabled using sshhoopptt,
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any unquoted instances of && in _s_t_r_i_n_g are replaced with the
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matching portion of _p_a_t_t_e_r_n.
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Quoting any part of _s_t_r_i_n_g inhibits replacement in the expansion
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of the quoted portion, including replacement strings stored in
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shell variables. Backslash will escape && in _s_t_r_i_n_g; the back-
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slash is removed in order to permit a literal && in the replace-
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ment string. Backslash can also be used to escape a backslash;
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\\\\ results in a literal backslash in the replacement. Users
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should take care if _s_t_r_i_n_g is double-quoted to avoid unwanted
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||||
interactions between the backslash and double-quoting, since
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backslash has special meaning within double quotes. Pattern
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substitution performs the check for unquoted && after expanding
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_s_t_r_i_n_g; shell programmers should quote any occurrences of && they
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want to be taken literally in the replacement and ensure any in-
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stances of && they want to be replaced are unquoted.
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If the nnooccaasseemmaattcchh shell option is enabled, the match is per-
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formed without regard to the case of alphabetic characters. If
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_p_a_r_a_m_e_t_e_r is @@ or **, the substitution operation is applied to
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each positional parameter in turn, and the expansion is the re-
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sultant list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted
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with @@ or **, the substitution operation is applied to each mem-
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ber of the array in turn, and the expansion is the resultant
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list.
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${_p_a_r_a_m_e_t_e_r^^_p_a_t_t_e_r_n}
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${_p_a_r_a_m_e_t_e_r^^^^_p_a_t_t_e_r_n}
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@@ -6597,4 +6607,4 @@ BBUUGGSS
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GNU Bash 5.2 2021 December 26 BASH(1)
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GNU Bash 5.2 2022 January 17 BASH(1)
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+21
-12
@@ -5,12 +5,12 @@
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.\" Case Western Reserve University
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.\" chet.ramey@case.edu
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.\"
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.\" Last Change: Sun Dec 26 16:02:07 EST 2021
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.\" Last Change: Mon Jan 17 17:27:05 EST 2022
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.\"
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.\" bash_builtins, strip all but Built-Ins section
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.if \n(zZ=1 .ig zZ
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.if \n(zY=1 .ig zY
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.TH BASH 1 "2021 December 26" "GNU Bash 5.2"
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.TH BASH 1 "2022 January 17" "GNU Bash 5.2"
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.\"
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.\" There's some problem with having a `@'
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.\" in a tagged paragraph with the BSD man macros.
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@@ -50,8 +50,8 @@ bash \- GNU Bourne-Again SHell
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[options]
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[command_string | file]
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.SH COPYRIGHT
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.if n Bash is Copyright (C) 1989-2021 by the Free Software Foundation, Inc.
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.if t Bash is Copyright \(co 1989-2021 by the Free Software Foundation, Inc.
|
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.if n Bash is Copyright (C) 1989-2022 by the Free Software Foundation, Inc.
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.if t Bash is Copyright \(co 1989-2022 by the Free Software Foundation, Inc.
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.SH DESCRIPTION
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||||
.B Bash
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is an \fBsh\fR-compatible command language interpreter that
|
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@@ -3373,18 +3373,27 @@ matches of \fIpattern\fP are deleted.
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If \fIstring\fP is null,
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matches of \fIpattern\fP are deleted
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||||
and the \fB/\fP following \fIpattern\fP may be omitted.
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.sp 1
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If the \fBpatsub_replacement\fP shell option is enabled using \fBshopt\fP,
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any unquoted instances of \fB&\fP in \fIstring\fP are replaced with the
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matching portion of \fIpattern\fP.
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Backslash is used to quote \fB&\fP in \fIstring\fP; the backslash is removed
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.sp 1
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Quoting any part of \fIstring\fP inhibits replacement in the
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expansion of the quoted portion, including replacement strings stored
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in shell variables.
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Backslash will escape \fB&\fP in \fIstring\fP; the backslash is removed
|
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in order to permit a literal \fB&\fP in the replacement string.
|
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Users should take care
|
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if \fIstring\fP is double-quoted to avoid unwanted interactions between
|
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the backslash and double-quoting.
|
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Pattern substitution performs the check for \fB&\fP after expanding
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\fIstring\fP; shell programmers should quote backslashes intended to escape
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the \fB&\fP and inhibit replacement so they survive any quote removal
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performed by the expansion of \fIstring\fP.
|
||||
Backslash can also be used to escape a backslash; \fB\e\e\fP results in
|
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a literal backslash in the replacement.
|
||||
Users should take care if \fIstring\fP is double-quoted to avoid
|
||||
unwanted interactions between the backslash and double-quoting, since
|
||||
backslash has special meaning within double quotes.
|
||||
Pattern substitution performs the check for unquoted \fB&\fP after
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expanding \fIstring\fP;
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shell programmers should quote any occurrences of \fB&\fP
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they want to be taken literally in the replacement
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and ensure any instances of \fB&\fP they want to be replaced are unquoted.
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.sp 1
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If the
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.B nocasematch
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shell option is enabled, the match is performed without regard to the case
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+178
-158
@@ -2,9 +2,9 @@ This is bashref.info, produced by makeinfo version 6.8 from
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bashref.texi.
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This text is a brief description of the features that are present in the
|
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Bash shell (version 5.2, 26 December 2021).
|
||||
Bash shell (version 5.2, 17 January 2022).
|
||||
|
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This is Edition 5.2, last updated 26 December 2021, of 'The GNU Bash
|
||||
This is Edition 5.2, last updated 17 January 2022, of 'The GNU Bash
|
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Reference Manual', for 'Bash', Version 5.2.
|
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Copyright (C) 1988-2021 Free Software Foundation, Inc.
|
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@@ -27,10 +27,10 @@ Bash Features
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*************
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||||
|
||||
This text is a brief description of the features that are present in the
|
||||
Bash shell (version 5.2, 26 December 2021). The Bash home page is
|
||||
Bash shell (version 5.2, 17 January 2022). The Bash home page is
|
||||
<http://www.gnu.org/software/bash/>.
|
||||
|
||||
This is Edition 5.2, last updated 26 December 2021, of 'The GNU Bash
|
||||
This is Edition 5.2, last updated 17 January 2022, of 'The GNU Bash
|
||||
Reference Manual', for 'Bash', Version 5.2.
|
||||
|
||||
Bash contains features that appear in other popular shells, and some
|
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@@ -2079,38 +2079,58 @@ omitted, the operator tests only for existence.
|
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If the 'patsub_replacement' shell option is enabled using 'shopt',
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any unquoted instances of '&' in STRING are replaced with the
|
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matching portion of PATTERN. This is intended to duplicate a
|
||||
common 'sed' idiom. Backslash is used to quote '&' in STRING; the
|
||||
backslash is removed in order to permit a literal '&' in the
|
||||
replacement string. Pattern substitution performs the check for
|
||||
'&' after expanding STRING, so users should take care to quote
|
||||
backslashes intended to escape the '&' and inhibit replacement so
|
||||
they survive any quote removal performed by the expansion of
|
||||
STRING. For instance,
|
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common 'sed' idiom.
|
||||
|
||||
Quoting any part of STRING inhibits replacement in the expansion of
|
||||
the quoted portion, including replacement strings stored in shell
|
||||
variables. Backslash will escape '&' in STRING; the backslash is
|
||||
removed in order to permit a literal '&' in the replacement string.
|
||||
Users should take care if STRING is double-quoted to avoid unwanted
|
||||
interactions between the backslash and double-quoting, since
|
||||
backslash has special meaning within double quotes. Pattern
|
||||
substitution performs the check for unquoted '&' after expanding
|
||||
STRING, so users should ensure to properly quote any occurrences of
|
||||
'&' they want to be taken literally in the replacement and ensure
|
||||
any instances of '&' they want to be replaced are unquoted.
|
||||
|
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For instance,
|
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|
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var=abcdef
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rep='& '
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echo ${var/abc/& }
|
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echo "${var/abc/& }"
|
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echo ${var/abc/"& "}
|
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echo ${var/abc/$rep}
|
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echo "${var/abc/$rep}"
|
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|
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will display three lines of "abc def", while
|
||||
will display four lines of "abc def", while
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|
||||
var=abcdef
|
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rep='& '
|
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echo ${var/abc/\& }
|
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echo "${var/abc/\& }"
|
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echo ${var/abc/"\& "}
|
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echo ${var/abc/"& "}
|
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echo ${var/abc/"$rep"}
|
||||
|
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will display two lines of "abc def" and a third line of "& def".
|
||||
The first two are replaced because the backslash is removed by
|
||||
quote removal performed during the expansion of STRING (the
|
||||
expansion is performed in a context that doesn't take any enclosing
|
||||
double quotes into account, as with other word expansions). In the
|
||||
third case, the double quotes affect the expansion of '\&', and,
|
||||
because '&' is not one of the characters for which backslash is
|
||||
special in double quotes, the backslash survives the expansion,
|
||||
inhibits the replacement, but is removed because it is treated
|
||||
specially. One could use '\\&', unquoted, as the replacement
|
||||
string to achive the same effect. It should rarely be necessary to
|
||||
enclose only STRING in double quotes.
|
||||
will display four lines of "& def". Like the pattern removal
|
||||
operators, double quotes surrounding the replacement string quote
|
||||
the expanded characters, while double quotes enclosing the entire
|
||||
parameter substitution do not, since the expansion is performed in
|
||||
a context that doesn't take any enclosing double quotes into
|
||||
account.
|
||||
|
||||
Since backslash can escape '&', it can also escape a backslash in
|
||||
the replacement string. This means that '\\' will insert a literal
|
||||
backslash into the replacement, so these two 'echo' commands
|
||||
|
||||
var=abcdef
|
||||
rep='\\&xyz'
|
||||
echo ${var/abc/\\&xyz}
|
||||
echo ${var/abc/$rep}
|
||||
|
||||
will both output '\abcxyzdef'.
|
||||
|
||||
It should rarely be necessary to enclose only STRING in double
|
||||
quotes.
|
||||
|
||||
If the 'nocasematch' shell option (see the description of 'shopt'
|
||||
in *note The Shopt Builtin::) is enabled, the match is performed
|
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@@ -12423,138 +12443,138 @@ D.5 Concept Index
|
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Tag Table:
|
||||
Node: Top897
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||||
Node: Introduction2817
|
||||
Node: What is Bash?3033
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Node: What is a shell?4147
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Node: Definitions6685
|
||||
Node: Basic Shell Features9636
|
||||
Node: Shell Syntax10855
|
||||
Node: Shell Operation11881
|
||||
Node: Quoting13174
|
||||
Node: Escape Character14478
|
||||
Node: Single Quotes14963
|
||||
Node: Double Quotes15311
|
||||
Node: ANSI-C Quoting16589
|
||||
Node: Locale Translation17899
|
||||
Node: Creating Internationalized Scripts19210
|
||||
Node: Comments23327
|
||||
Node: Shell Commands23945
|
||||
Node: Reserved Words24883
|
||||
Node: Simple Commands25639
|
||||
Node: Pipelines26293
|
||||
Node: Lists29252
|
||||
Node: Compound Commands31047
|
||||
Node: Looping Constructs32059
|
||||
Node: Conditional Constructs34554
|
||||
Node: Command Grouping48898
|
||||
Node: Coprocesses50376
|
||||
Node: GNU Parallel53039
|
||||
Node: Shell Functions53956
|
||||
Node: Shell Parameters61247
|
||||
Node: Positional Parameters65635
|
||||
Node: Special Parameters66537
|
||||
Node: Shell Expansions69751
|
||||
Node: Brace Expansion71878
|
||||
Node: Tilde Expansion74612
|
||||
Node: Shell Parameter Expansion77233
|
||||
Node: Command Substitution95099
|
||||
Node: Arithmetic Expansion96454
|
||||
Node: Process Substitution97422
|
||||
Node: Word Splitting98542
|
||||
Node: Filename Expansion100486
|
||||
Node: Pattern Matching103235
|
||||
Node: Quote Removal107843
|
||||
Node: Redirections108138
|
||||
Node: Executing Commands117798
|
||||
Node: Simple Command Expansion118468
|
||||
Node: Command Search and Execution120578
|
||||
Node: Command Execution Environment122956
|
||||
Node: Environment125991
|
||||
Node: Exit Status127654
|
||||
Node: Signals129438
|
||||
Node: Shell Scripts132887
|
||||
Node: Shell Builtin Commands135914
|
||||
Node: Bourne Shell Builtins137952
|
||||
Node: Bash Builtins159413
|
||||
Node: Modifying Shell Behavior190269
|
||||
Node: The Set Builtin190614
|
||||
Node: The Shopt Builtin201215
|
||||
Node: Special Builtins217127
|
||||
Node: Shell Variables218106
|
||||
Node: Bourne Shell Variables218543
|
||||
Node: Bash Variables220647
|
||||
Node: Bash Features253463
|
||||
Node: Invoking Bash254476
|
||||
Node: Bash Startup Files260489
|
||||
Node: Interactive Shells265592
|
||||
Node: What is an Interactive Shell?266002
|
||||
Node: Is this Shell Interactive?266651
|
||||
Node: Interactive Shell Behavior267466
|
||||
Node: Bash Conditional Expressions271095
|
||||
Node: Shell Arithmetic275737
|
||||
Node: Aliases278681
|
||||
Node: Arrays281294
|
||||
Node: The Directory Stack287541
|
||||
Node: Directory Stack Builtins288325
|
||||
Node: Controlling the Prompt292585
|
||||
Node: The Restricted Shell295550
|
||||
Node: Bash POSIX Mode298160
|
||||
Node: Shell Compatibility Mode309433
|
||||
Node: Job Control317462
|
||||
Node: Job Control Basics317922
|
||||
Node: Job Control Builtins322924
|
||||
Node: Job Control Variables328324
|
||||
Node: Command Line Editing329480
|
||||
Node: Introduction and Notation331151
|
||||
Node: Readline Interaction332774
|
||||
Node: Readline Bare Essentials333965
|
||||
Node: Readline Movement Commands335748
|
||||
Node: Readline Killing Commands336708
|
||||
Node: Readline Arguments338626
|
||||
Node: Searching339670
|
||||
Node: Readline Init File341856
|
||||
Node: Readline Init File Syntax343117
|
||||
Node: Conditional Init Constructs364605
|
||||
Node: Sample Init File368801
|
||||
Node: Bindable Readline Commands371925
|
||||
Node: Commands For Moving373129
|
||||
Node: Commands For History375180
|
||||
Node: Commands For Text380174
|
||||
Node: Commands For Killing383823
|
||||
Node: Numeric Arguments386856
|
||||
Node: Commands For Completion387995
|
||||
Node: Keyboard Macros392186
|
||||
Node: Miscellaneous Commands392873
|
||||
Node: Readline vi Mode398812
|
||||
Node: Programmable Completion399719
|
||||
Node: Programmable Completion Builtins407499
|
||||
Node: A Programmable Completion Example418194
|
||||
Node: Using History Interactively423441
|
||||
Node: Bash History Facilities424125
|
||||
Node: Bash History Builtins427130
|
||||
Node: History Interaction432138
|
||||
Node: Event Designators435758
|
||||
Node: Word Designators437112
|
||||
Node: Modifiers438872
|
||||
Node: Installing Bash440683
|
||||
Node: Basic Installation441820
|
||||
Node: Compilers and Options445542
|
||||
Node: Compiling For Multiple Architectures446283
|
||||
Node: Installation Names447976
|
||||
Node: Specifying the System Type450085
|
||||
Node: Sharing Defaults450801
|
||||
Node: Operation Controls451474
|
||||
Node: Optional Features452432
|
||||
Node: Reporting Bugs463650
|
||||
Node: Major Differences From The Bourne Shell464925
|
||||
Node: GNU Free Documentation License481775
|
||||
Node: Indexes506952
|
||||
Node: Builtin Index507406
|
||||
Node: Reserved Word Index514233
|
||||
Node: Variable Index516681
|
||||
Node: Function Index533173
|
||||
Node: Concept Index546957
|
||||
Node: Top895
|
||||
Node: Introduction2813
|
||||
Node: What is Bash?3029
|
||||
Node: What is a shell?4143
|
||||
Node: Definitions6681
|
||||
Node: Basic Shell Features9632
|
||||
Node: Shell Syntax10851
|
||||
Node: Shell Operation11877
|
||||
Node: Quoting13170
|
||||
Node: Escape Character14474
|
||||
Node: Single Quotes14959
|
||||
Node: Double Quotes15307
|
||||
Node: ANSI-C Quoting16585
|
||||
Node: Locale Translation17895
|
||||
Node: Creating Internationalized Scripts19206
|
||||
Node: Comments23323
|
||||
Node: Shell Commands23941
|
||||
Node: Reserved Words24879
|
||||
Node: Simple Commands25635
|
||||
Node: Pipelines26289
|
||||
Node: Lists29248
|
||||
Node: Compound Commands31043
|
||||
Node: Looping Constructs32055
|
||||
Node: Conditional Constructs34550
|
||||
Node: Command Grouping48894
|
||||
Node: Coprocesses50372
|
||||
Node: GNU Parallel53035
|
||||
Node: Shell Functions53952
|
||||
Node: Shell Parameters61243
|
||||
Node: Positional Parameters65631
|
||||
Node: Special Parameters66533
|
||||
Node: Shell Expansions69747
|
||||
Node: Brace Expansion71874
|
||||
Node: Tilde Expansion74608
|
||||
Node: Shell Parameter Expansion77229
|
||||
Node: Command Substitution95566
|
||||
Node: Arithmetic Expansion96921
|
||||
Node: Process Substitution97889
|
||||
Node: Word Splitting99009
|
||||
Node: Filename Expansion100953
|
||||
Node: Pattern Matching103702
|
||||
Node: Quote Removal108310
|
||||
Node: Redirections108605
|
||||
Node: Executing Commands118265
|
||||
Node: Simple Command Expansion118935
|
||||
Node: Command Search and Execution121045
|
||||
Node: Command Execution Environment123423
|
||||
Node: Environment126458
|
||||
Node: Exit Status128121
|
||||
Node: Signals129905
|
||||
Node: Shell Scripts133354
|
||||
Node: Shell Builtin Commands136381
|
||||
Node: Bourne Shell Builtins138419
|
||||
Node: Bash Builtins159880
|
||||
Node: Modifying Shell Behavior190736
|
||||
Node: The Set Builtin191081
|
||||
Node: The Shopt Builtin201682
|
||||
Node: Special Builtins217594
|
||||
Node: Shell Variables218573
|
||||
Node: Bourne Shell Variables219010
|
||||
Node: Bash Variables221114
|
||||
Node: Bash Features253930
|
||||
Node: Invoking Bash254943
|
||||
Node: Bash Startup Files260956
|
||||
Node: Interactive Shells266059
|
||||
Node: What is an Interactive Shell?266469
|
||||
Node: Is this Shell Interactive?267118
|
||||
Node: Interactive Shell Behavior267933
|
||||
Node: Bash Conditional Expressions271562
|
||||
Node: Shell Arithmetic276204
|
||||
Node: Aliases279148
|
||||
Node: Arrays281761
|
||||
Node: The Directory Stack288008
|
||||
Node: Directory Stack Builtins288792
|
||||
Node: Controlling the Prompt293052
|
||||
Node: The Restricted Shell296017
|
||||
Node: Bash POSIX Mode298627
|
||||
Node: Shell Compatibility Mode309900
|
||||
Node: Job Control317929
|
||||
Node: Job Control Basics318389
|
||||
Node: Job Control Builtins323391
|
||||
Node: Job Control Variables328791
|
||||
Node: Command Line Editing329947
|
||||
Node: Introduction and Notation331618
|
||||
Node: Readline Interaction333241
|
||||
Node: Readline Bare Essentials334432
|
||||
Node: Readline Movement Commands336215
|
||||
Node: Readline Killing Commands337175
|
||||
Node: Readline Arguments339093
|
||||
Node: Searching340137
|
||||
Node: Readline Init File342323
|
||||
Node: Readline Init File Syntax343584
|
||||
Node: Conditional Init Constructs365072
|
||||
Node: Sample Init File369268
|
||||
Node: Bindable Readline Commands372392
|
||||
Node: Commands For Moving373596
|
||||
Node: Commands For History375647
|
||||
Node: Commands For Text380641
|
||||
Node: Commands For Killing384290
|
||||
Node: Numeric Arguments387323
|
||||
Node: Commands For Completion388462
|
||||
Node: Keyboard Macros392653
|
||||
Node: Miscellaneous Commands393340
|
||||
Node: Readline vi Mode399279
|
||||
Node: Programmable Completion400186
|
||||
Node: Programmable Completion Builtins407966
|
||||
Node: A Programmable Completion Example418661
|
||||
Node: Using History Interactively423908
|
||||
Node: Bash History Facilities424592
|
||||
Node: Bash History Builtins427597
|
||||
Node: History Interaction432605
|
||||
Node: Event Designators436225
|
||||
Node: Word Designators437579
|
||||
Node: Modifiers439339
|
||||
Node: Installing Bash441150
|
||||
Node: Basic Installation442287
|
||||
Node: Compilers and Options446009
|
||||
Node: Compiling For Multiple Architectures446750
|
||||
Node: Installation Names448443
|
||||
Node: Specifying the System Type450552
|
||||
Node: Sharing Defaults451268
|
||||
Node: Operation Controls451941
|
||||
Node: Optional Features452899
|
||||
Node: Reporting Bugs464117
|
||||
Node: Major Differences From The Bourne Shell465392
|
||||
Node: GNU Free Documentation License482242
|
||||
Node: Indexes507419
|
||||
Node: Builtin Index507873
|
||||
Node: Reserved Word Index514700
|
||||
Node: Variable Index517148
|
||||
Node: Function Index533640
|
||||
Node: Concept Index547424
|
||||
|
||||
End Tag Table
|
||||
|
||||
|
||||
+43
-22
@@ -2444,46 +2444,67 @@ If the @code{patsub_replacement} shell option is enabled using @code{shopt},
|
||||
any unquoted instances of @samp{&} in @var{string} are replaced with the
|
||||
matching portion of @var{pattern}.
|
||||
This is intended to duplicate a common @code{sed} idiom.
|
||||
Backslash is used to quote @samp{&} in @var{string}; the backslash is removed
|
||||
|
||||
Quoting any part of @var{string} inhibits replacement in the
|
||||
expansion of the quoted portion, including replacement strings stored
|
||||
in shell variables.
|
||||
Backslash will escape @samp{&} in @var{string}; the backslash is removed
|
||||
in order to permit a literal @samp{&} in the replacement string.
|
||||
Pattern substitution performs the check for @samp{&} after expanding
|
||||
@var{string},
|
||||
so users should take care to quote backslashes intended to escape
|
||||
the @samp{&} and inhibit replacement so they survive any quote removal
|
||||
performed by the expansion of @var{string}.
|
||||
Users should take care if @var{string} is double-quoted to avoid
|
||||
unwanted interactions between the backslash and double-quoting, since
|
||||
backslash has special meaning within double quotes.
|
||||
Pattern substitution performs the check for unquoted @samp{&} after
|
||||
expanding @var{string},
|
||||
so users should ensure to properly quote any occurrences of @samp{&}
|
||||
they want to be taken literally in the replacement
|
||||
and ensure any instances of @samp{&} they want to be replaced are unquoted.
|
||||
|
||||
For instance,
|
||||
|
||||
@example
|
||||
var=abcdef
|
||||
rep='& '
|
||||
echo $@{var/abc/& @}
|
||||
echo "$@{var/abc/& @}"
|
||||
echo $@{var/abc/"& "@}
|
||||
echo $@{var/abc/$rep@}
|
||||
echo "$@{var/abc/$rep@}"
|
||||
@end example
|
||||
|
||||
@noindent
|
||||
will display three lines of "abc def", while
|
||||
will display four lines of "abc def", while
|
||||
|
||||
@example
|
||||
var=abcdef
|
||||
rep='& '
|
||||
echo $@{var/abc/\& @}
|
||||
echo "$@{var/abc/\& @}"
|
||||
echo $@{var/abc/"\& "@}
|
||||
echo $@{var/abc/"& "@}
|
||||
echo $@{var/abc/"$rep"@}
|
||||
@end example
|
||||
|
||||
@noindent
|
||||
will display two lines of "abc def" and a third line of "& def".
|
||||
The first two are replaced because the backslash is removed by quote
|
||||
removal performed during the expansion of @var{string}
|
||||
(the expansion is performed in a
|
||||
context that doesn't take any enclosing double quotes into account, as
|
||||
with other word expansions).
|
||||
In the third case, the double quotes affect the expansion
|
||||
of @samp{\&}, and, because @samp{&} is not one of the characters for
|
||||
which backslash is special in double quotes,
|
||||
the backslash survives the expansion, inhibits the replacement,
|
||||
but is removed because it is treated specially.
|
||||
One could use @samp{\\&}, unquoted, as the replacement string to achive
|
||||
the same effect.
|
||||
will display four lines of "& def".
|
||||
Like the pattern removal operators, double quotes surrounding the
|
||||
replacement string quote the expanded characters, while double quotes
|
||||
enclosing the entire parameter substitution do not, since
|
||||
the expansion is performed in a
|
||||
context that doesn't take any enclosing double quotes into account.
|
||||
|
||||
Since backslash can escape @samp{&}, it can also escape a backslash in
|
||||
the replacement string.
|
||||
This means that @samp{\\} will insert a literal
|
||||
backslash into the replacement, so these two @code{echo} commands
|
||||
|
||||
@example
|
||||
var=abcdef
|
||||
rep='\\&xyz'
|
||||
echo $@{var/abc/\\&xyz@}
|
||||
echo $@{var/abc/$rep@}
|
||||
@end example
|
||||
|
||||
@noindent
|
||||
will both output @samp{\abcxyzdef}.
|
||||
|
||||
It should rarely be necessary to enclose only @var{string} in double
|
||||
quotes.
|
||||
|
||||
|
||||
+4
-4
@@ -1,11 +1,11 @@
|
||||
@ignore
|
||||
Copyright (C) 1988-2021 Free Software Foundation, Inc.
|
||||
Copyright (C) 1988-2022 Free Software Foundation, Inc.
|
||||
@end ignore
|
||||
|
||||
@set LASTCHANGE Sun Dec 26 16:02:48 EST 2021
|
||||
@set LASTCHANGE Mon Jan 17 17:03:25 EST 2022
|
||||
|
||||
@set EDITION 5.2
|
||||
@set VERSION 5.2
|
||||
|
||||
@set UPDATED 26 December 2021
|
||||
@set UPDATED-MONTH December 2021
|
||||
@set UPDATED 17 January 2022
|
||||
@set UPDATED-MONTH January 2022
|
||||
|
||||
Reference in New Issue
Block a user