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enable support for using `&' in the pattern substitution replacement string

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This commit is contained in:
Chet Ramey
2021-10-04 15:30:21 -04:00
parent 70d7c6430d
commit f188aa6a01
22 changed files with 518 additions and 209 deletions
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doc/bash.0
+32 -15
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@@ -1827,17 +1827,32 @@ EEXXPPAANNSSIIOONN
turn, and the expansion is the resultant list.
${_p_a_r_a_m_e_t_e_r//_p_a_t_t_e_r_n//_s_t_r_i_n_g}
${_p_a_r_a_m_e_t_e_r////_p_a_t_t_e_r_n//_s_t_r_i_n_g}
${_p_a_r_a_m_e_t_e_r//##_p_a_t_t_e_r_n//_s_t_r_i_n_g}
${_p_a_r_a_m_e_t_e_r//%%_p_a_t_t_e_r_n//_s_t_r_i_n_g}
PPaatttteerrnn ssuubbssttiittuuttiioonn. The _p_a_t_t_e_r_n is expanded to produce a pat-
tern just as in pathname expansion, _P_a_r_a_m_e_t_e_r is expanded and
tern just as in pathname expansion. _P_a_r_a_m_e_t_e_r is expanded and
the longest match of _p_a_t_t_e_r_n against its value is replaced with
_s_t_r_i_n_g. The match is performed using the rules described under
PPaatttteerrnn MMaattcchhiinngg below. If _p_a_t_t_e_r_n begins with //, all matches
of _p_a_t_t_e_r_n are replaced with _s_t_r_i_n_g. Normally only the first
match is replaced. If _p_a_t_t_e_r_n begins with ##, it must match at
the beginning of the expanded value of _p_a_r_a_m_e_t_e_r. If _p_a_t_t_e_r_n
begins with %%, it must match at the end of the expanded value of
_p_a_r_a_m_e_t_e_r. If _s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are deleted
and the // following _p_a_t_t_e_r_n may be omitted. If the nnooccaasseemmaattcchh
_s_t_r_i_n_g. _s_t_r_i_n_g undergoes tilde expansion, parameter and vari-
able expansion, arithmetic expansion, command and process sub-
stitution, and quote removal. The match is performed using the
rules described under PPaatttteerrnn MMaattcchhiinngg below. In the first form
above, only the first match is replaced. If there are two
slashes separating _p_a_r_a_m_e_t_e_r and _p_a_t_t_e_r_n (the second form
above), all matches of _p_a_t_t_e_r_n are replaced with _s_t_r_i_n_g. If
_p_a_t_t_e_r_n is preceded by ## (the third form above), it must match
at the beginning of the expanded value of _p_a_r_a_m_e_t_e_r. If _p_a_t_t_e_r_n
is preceded by %% (the fourth form above), it must match at the
end of the expanded value of _p_a_r_a_m_e_t_e_r. If the expansion of
_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
null, matches of _p_a_t_t_e_r_n are deleted and the // following _p_a_t_t_e_r_n
may be omitted. Any unquoted instances of && in _s_t_r_i_n_g are re-
placed with the matching portion of _p_a_t_t_e_r_n. Backslash is used
to quote && in _s_t_r_i_n_g; users should take care if _s_t_r_i_n_g is dou-
ble-quoted to avoid unwanted interactions between the backslash
and double-quoting. Pattern substitution performs the check for
&& before expanding _s_t_r_i_n_g to catch backslashes escaping the &&
before they are removed by the expansion. If the nnooccaasseemmaattcchh
shell option is enabled, the match is performed without regard
to the case of alphabetic characters. If _p_a_r_a_m_e_t_e_r is @@ or **,
the substitution operation is applied to each positional parame-
@@ -2695,11 +2710,13 @@ SSIIMMPPLLEE CCOOMMMMAANNDD EEXXPPAANNSSIIOONN
able.
If no command name results, the variable assignments affect the current
shell environment. Otherwise, the variables are added to the environ-
ment of the executed command and do not affect the current shell envi-
ronment. If any of the assignments attempts to assign a value to a
readonly variable, an error occurs, and the command exits with a non-
zero status.
shell environment. In the case of such a command (one that consists
only of assignment statements and redirections), assignment statements
are performed before redirections. Otherwise, the variables are added
to the environment of the executed command and do not affect the cur-
rent shell environment. If any of the assignments attempts to assign a
value to a readonly variable, an error occurs, and the command exits
with a non-zero status.
If no command name results, redirections are performed, but do not af-
fect the current shell environment. A redirection error causes the
@@ -6517,4 +6534,4 @@ BBUUGGSS
GNU Bash 5.1 2021 August 23 BASH(1)
GNU Bash 5.1 2021 October 1 BASH(1)
doc/bash.1
+36 -10
View File
@@ -5,12 +5,12 @@
.\" Case Western Reserve University
.\" chet.ramey@case.edu
.\"
.\" Last Change: Mon Aug 23 10:08:28 EDT 2021
.\" Last Change: Fri Oct 1 14:20:30 EDT 2021
.\"
.\" bash_builtins, strip all but Built-Ins section
.if \n(zZ=1 .ig zZ
.if \n(zY=1 .ig zY
.TH BASH 1 "2021 August 23" "GNU Bash 5.1"
.TH BASH 1 "2021 October 1" "GNU Bash 5.1"
.\"
.\" There's some problem with having a `@'
.\" in a tagged paragraph with the BSD man macros.
@@ -3336,22 +3336,48 @@ the pattern removal operation is applied to each member of the
array in turn, and the expansion is the resultant list.
.TP
${\fIparameter\fP\fB/\fP\fIpattern\fP\fB/\fP\fIstring\fP}
.PD 0
.TP
${\fIparameter\fP\fB//\fP\fIpattern\fP\fB/\fP\fIstring\fP}
.TP
${\fIparameter\fP\fB/#\fP\fIpattern\fP\fB/\fP\fIstring\fP}
.TP
${\fIparameter\fP\fB/%\fP\fIpattern\fP\fB/\fP\fIstring\fP}
.PD
\fBPattern substitution\fP.
The \fIpattern\fP is expanded to produce a pattern just as in
pathname expansion,
pathname expansion.
\fIParameter\fP is expanded and the longest match of \fIpattern\fP
against its value is replaced with \fIstring\fP.
\fIstring\fP undergoes tilde expansion, parameter and variable expansion,
arithmetic expansion, command and process substitution, and quote removal.
The match is performed using the rules described under
.B Pattern Matching
below.
If \fIpattern\fP begins with \fB/\fP, all matches of \fIpattern\fP are
replaced with \fIstring\fP. Normally only the first match is replaced.
If \fIpattern\fP begins with \fB#\fP, it must match at the beginning
of the expanded value of \fIparameter\fP.
If \fIpattern\fP begins with \fB%\fP, it must match at the end
of the expanded value of \fIparameter\fP.
If \fIstring\fP is null, matches of \fIpattern\fP are deleted
In the first form above, only the first match is replaced.
If there are two slashes separating \fIparameter\fP and \fIpattern\fP
(the second form above), all matches of \fIpattern\fP are
replaced with \fIstring\fP.
If \fIpattern\fP is preceded by \fB#\fP (the third form above),
it must match at the beginning of the expanded value of \fIparameter\fP.
If \fIpattern\fP is preceded by \fB%\fP (the fourth form above),
it must match at the end of the expanded value of \fIparameter\fP.
If the expansion of \fIstring\fP is null,
matches of \fIpattern\fP are deleted.
If \fIstring\fP is null,
matches of \fIpattern\fP are deleted
and the \fB/\fP following \fIpattern\fP may be omitted.
Any unquoted instances of \fB&\fP in \fIstring\fP are replaced with the
matching portion of \fIpattern\fP.
Backslash is used to quote \fB&\fP in \fIstring\fP; the backslash is removed
in order to permit a literal \fB&\fP in the replacement string.
Users should take care
if \fIstring\fP is double-quoted to avoid unwanted interactions between
the backslash and double-quoting.
Pattern substitution performs the check for \fB&\fP after expanding
\fIstring\fP; shell programmers should quote backslashes intended to escape
the \fB&\fP and inhibit replacement so they survive any quote removal
performed by the expansion of \fIstring\fP.
If the
.B nocasematch
shell option is enabled, the match is performed without regard to the case
doc/bashref.info
+200 -137
View File
@@ -1,10 +1,10 @@
This is bashref.info, produced by makeinfo version 6.7 from
This is bashref.info, produced by makeinfo version 6.8 from
bashref.texi.
This text is a brief description of the features that are present in the
Bash shell (version 5.1, 23 August 2021).
Bash shell (version 5.1, 1 October 2021).
This is Edition 5.1, last updated 23 August 2021, of 'The GNU Bash
This is Edition 5.1, last updated 1 October 2021, of 'The GNU Bash
Reference Manual', for 'Bash', Version 5.1.
Copyright (C) 1988-2021 Free Software Foundation, Inc.
@@ -27,10 +27,10 @@ Bash Features
*************
This text is a brief description of the features that are present in the
Bash shell (version 5.1, 23 August 2021). The Bash home page is
Bash shell (version 5.1, 1 October 2021). The Bash home page is
<http://www.gnu.org/software/bash/>.
This is Edition 5.1, last updated 23 August 2021, of 'The GNU Bash
This is Edition 5.1, last updated 1 October 2021, of 'The GNU Bash
Reference Manual', for 'Bash', Version 5.1.
Bash contains features that appear in other popular shells, and some
@@ -1831,22 +1831,39 @@ omitted, the operator tests only for existence.
If PARAMETER is unset or null, the expansion of WORD is
substituted. Otherwise, the value of PARAMETER is substituted.
$ v=123
$ echo ${v-unset}
123
'${PARAMETER:=WORD}'
If PARAMETER is unset or null, the expansion of WORD is assigned to
PARAMETER. The value of PARAMETER is then substituted. Positional
parameters and special parameters may not be assigned to in this
way.
$ var=
$ : ${var:=DEFAULT}
$ echo $var
DEFAULT
'${PARAMETER:?WORD}'
If PARAMETER is null or unset, the expansion of WORD (or a message
to that effect if WORD is not present) is written to the standard
error and the shell, if it is not interactive, exits. Otherwise,
the value of PARAMETER is substituted.
$ var=
$ : ${var:?var is unset or null}
bash: var: var is unset or null
'${PARAMETER:+WORD}'
If PARAMETER is null or unset, nothing is substituted, otherwise
the expansion of WORD is substituted.
$ var=123
$ echo ${var:+var is set and not null}
var is set and not null
'${PARAMETER:OFFSET}'
'${PARAMETER:OFFSET:LENGTH}'
This is referred to as Substring Expansion. It expands to up to
@@ -2037,26 +2054,66 @@ omitted, the operator tests only for existence.
array in turn, and the expansion is the resultant list.
'${PARAMETER/PATTERN/STRING}'
'${PARAMETER//PATTERN/STRING}'
'${PARAMETER/#PATTERN/STRING}'
'${PARAMETER/%PATTERN/STRING}'
The PATTERN is expanded to produce a pattern just as in filename
expansion. PARAMETER is expanded and the longest match of PATTERN
against its value is replaced with STRING. The match is performed
according to the rules described below (*note Pattern Matching::).
If PATTERN begins with '/', all matches of PATTERN are replaced
with STRING. Normally only the first match is replaced. If
PATTERN begins with '#', it must match at the beginning of the
expanded value of PARAMETER. If PATTERN begins with '%', it must
match at the end of the expanded value of PARAMETER. If STRING is
null, matches of PATTERN are deleted and the '/' following PATTERN
may be omitted. If the 'nocasematch' shell option (see the
description of 'shopt' in *note The Shopt Builtin::) is enabled,
the match is performed without regard to the case of alphabetic
characters. If PARAMETER is '@' or '*', the substitution operation
is applied to each positional parameter in turn, and the expansion
is the resultant list. If PARAMETER is an array variable
subscripted with '@' or '*', the substitution operation is applied
to each member of the array in turn, and the expansion is the
resultant list.
against its value is replaced with STRING. STRING undergoes tilde
expansion, parameter and variable expansion, arithmetic expansion,
command and process substitution, and quote removal. The match is
performed according to the rules described below (*note Pattern
Matching::).
In the first form above, only the first match is replaced. If
there are two slashes separating PARAMETER and PATTERN (the second
form above), all matches of PATTERN are replaced with STRING. If
PATTERN is preceded by '#' (the third form above), it must match at
the beginning of the expanded value of PARAMETER. If PATTERN is
preceded by '%' (the fourth form above), it must match at the end
of the expanded value of PARAMETER. If the expansion of STRING is
null, matches of PATTERN are deleted. If STRING is null, matches
of PATTERN are deleted and the '/' following PATTERN may be
omitted.
Any unquoted instances of '&' in STRING are replaced with the
matching portion of PATTERN. This is intended to duplicate a
common 'sed' idiom. Backslash is used to quote '&' in STRING;
users should take care if STRING is double-quoted to avoid unwanted
interactions between the backslash and double-quoting. For
instance,
var=abcdef
echo ${var/abc/& }
echo "${var/abc/& }"
echo ${var/abc/"& "}
will display three lines of "abc def", while
var=abcdef
echo ${var/abc/\& }
echo "${var/abc/\& }"
echo ${var/abc/"\& "}
will display two lines of "& def" and a third line of "\& def".
This is because '&' is not one of the characters for which
backslash is special in double quotes, and the expansion of STRING
is performed in a context that doesn't take the enclosing double
quotes into account. It should rarely be necessary to enclose only
STRING in double quotes.
Pattern substitution performs the check for '&' before expanding
STRING to catch backslashes escaping the '&' before they are
removed by the expansion.
If the 'nocasematch' shell option (see the description of 'shopt'
in *note The Shopt Builtin::) is enabled, the match is performed
without regard to the case of alphabetic characters. If PARAMETER
is '@' or '*', the substitution operation is applied to each
positional parameter in turn, and the expansion is the resultant
list. If PARAMETER is an array variable subscripted with '@' or
'*', the substitution operation is applied to each member of the
array in turn, and the expansion is the resultant list.
'${PARAMETER^PATTERN}'
'${PARAMETER^^PATTERN}'
@@ -2067,18 +2124,22 @@ omitted, the operator tests only for existence.
filename expansion. Each character in the expanded value of
PARAMETER is tested against PATTERN, and, if it matches the
pattern, its case is converted. The pattern should not attempt to
match more than one character. The '^' operator converts lowercase
letters matching PATTERN to uppercase; the ',' operator converts
matching uppercase letters to lowercase. The '^^' and ',,'
expansions convert each matched character in the expanded value;
the '^' and ',' expansions match and convert only the first
character in the expanded value. If PATTERN is omitted, it is
treated like a '?', which matches every character. If PARAMETER is
'@' or '*', the case modification operation is applied to each
positional parameter in turn, and the expansion is the resultant
list. If PARAMETER is an array variable subscripted with '@' or
'*', the case modification operation is applied to each member of
the array in turn, and the expansion is the resultant list.
match more than one character.
The '^' operator converts lowercase letters matching PATTERN to
uppercase; the ',' operator converts matching uppercase letters to
lowercase. The '^^' and ',,' expansions convert each matched
character in the expanded value; the '^' and ',' expansions match
and convert only the first character in the expanded value. If
PATTERN is omitted, it is treated like a '?', which matches every
character.
If PARAMETER is '@' or '*', the case modification operation is
applied to each positional parameter in turn, and the expansion is
the resultant list. If PARAMETER is an array variable subscripted
with '@' or '*', the case modification operation is applied to each
member of the array in turn, and the expansion is the resultant
list.
'${PARAMETER@OPERATOR}'
The expansion is either a transformation of the value of PARAMETER
@@ -2697,11 +2758,13 @@ following order.
expansion, and quote removal before being assigned to the variable.
If no command name results, the variable assignments affect the
current shell environment. Otherwise, the variables are added to the
environment of the executed command and do not affect the current shell
environment. If any of the assignments attempts to assign a value to a
readonly variable, an error occurs, and the command exits with a
non-zero status.
current shell environment. In the case of such a command (one that
consists only of assignment statements and redirections), assignment
statements are performed before redirections. Otherwise, the variables
are added to the environment of the executed command and do not affect
the current shell environment. If any of the assignments attempts to
assign a value to a readonly variable, an error occurs, and the command
exits with a non-zero status.
If no command name results, redirections are performed, but do not
affect the current shell environment. A redirection error causes the
@@ -12264,103 +12327,103 @@ Node: Shell Expansions69743
Node: Brace Expansion71870
Node: Tilde Expansion74604
Node: Shell Parameter Expansion77225
Node: Command Substitution92528
Node: Arithmetic Expansion93883
Node: Process Substitution94851
Node: Word Splitting95971
Node: Filename Expansion97915
Node: Pattern Matching100515
Node: Quote Removal105123
Node: Redirections105418
Node: Executing Commands115078
Node: Simple Command Expansion115748
Node: Command Search and Execution117702
Node: Command Execution Environment120080
Node: Environment123115
Node: Exit Status124778
Node: Signals126562
Node: Shell Scripts128529
Node: Shell Builtin Commands131556
Node: Bourne Shell Builtins133594
Node: Bash Builtins155055
Node: Modifying Shell Behavior185872
Node: The Set Builtin186217
Node: The Shopt Builtin196630
Node: Special Builtins212059
Node: Shell Variables213038
Node: Bourne Shell Variables213475
Node: Bash Variables215579
Node: Bash Features248394
Node: Invoking Bash249407
Node: Bash Startup Files255420
Node: Interactive Shells260523
Node: What is an Interactive Shell?260933
Node: Is this Shell Interactive?261582
Node: Interactive Shell Behavior262397
Node: Bash Conditional Expressions265910
Node: Shell Arithmetic270552
Node: Aliases273496
Node: Arrays276109
Node: The Directory Stack282118
Node: Directory Stack Builtins282902
Node: Controlling the Prompt287162
Node: The Restricted Shell290127
Node: Bash POSIX Mode292724
Node: Shell Compatibility Mode303997
Node: Job Control310653
Node: Job Control Basics311113
Node: Job Control Builtins316115
Node: Job Control Variables321515
Node: Command Line Editing322671
Node: Introduction and Notation324342
Node: Readline Interaction325965
Node: Readline Bare Essentials327156
Node: Readline Movement Commands328939
Node: Readline Killing Commands329899
Node: Readline Arguments331817
Node: Searching332861
Node: Readline Init File335047
Node: Readline Init File Syntax336308
Node: Conditional Init Constructs357588
Node: Sample Init File361784
Node: Bindable Readline Commands364908
Node: Commands For Moving366112
Node: Commands For History368163
Node: Commands For Text373157
Node: Commands For Killing376806
Node: Numeric Arguments379839
Node: Commands For Completion380978
Node: Keyboard Macros385169
Node: Miscellaneous Commands385856
Node: Readline vi Mode391795
Node: Programmable Completion392702
Node: Programmable Completion Builtins400482
Node: A Programmable Completion Example411177
Node: Using History Interactively416424
Node: Bash History Facilities417108
Node: Bash History Builtins420113
Node: History Interaction425121
Node: Event Designators428741
Node: Word Designators430095
Node: Modifiers431855
Node: Installing Bash433666
Node: Basic Installation434803
Node: Compilers and Options438061
Node: Compiling For Multiple Architectures438802
Node: Installation Names440495
Node: Specifying the System Type441313
Node: Sharing Defaults442029
Node: Operation Controls442702
Node: Optional Features443660
Node: Reporting Bugs454460
Node: Major Differences From The Bourne Shell455735
Node: GNU Free Documentation License472585
Node: Indexes497762
Node: Builtin Index498216
Node: Reserved Word Index505043
Node: Variable Index507491
Node: Function Index523983
Node: Concept Index537767
Node: Command Substitution94537
Node: Arithmetic Expansion95892
Node: Process Substitution96860
Node: Word Splitting97980
Node: Filename Expansion99924
Node: Pattern Matching102524
Node: Quote Removal107132
Node: Redirections107427
Node: Executing Commands117087
Node: Simple Command Expansion117757
Node: Command Search and Execution119867
Node: Command Execution Environment122245
Node: Environment125280
Node: Exit Status126943
Node: Signals128727
Node: Shell Scripts130694
Node: Shell Builtin Commands133721
Node: Bourne Shell Builtins135759
Node: Bash Builtins157220
Node: Modifying Shell Behavior188037
Node: The Set Builtin188382
Node: The Shopt Builtin198795
Node: Special Builtins214224
Node: Shell Variables215203
Node: Bourne Shell Variables215640
Node: Bash Variables217744
Node: Bash Features250559
Node: Invoking Bash251572
Node: Bash Startup Files257585
Node: Interactive Shells262688
Node: What is an Interactive Shell?263098
Node: Is this Shell Interactive?263747
Node: Interactive Shell Behavior264562
Node: Bash Conditional Expressions268075
Node: Shell Arithmetic272717
Node: Aliases275661
Node: Arrays278274
Node: The Directory Stack284283
Node: Directory Stack Builtins285067
Node: Controlling the Prompt289327
Node: The Restricted Shell292292
Node: Bash POSIX Mode294889
Node: Shell Compatibility Mode306162
Node: Job Control312818
Node: Job Control Basics313278
Node: Job Control Builtins318280
Node: Job Control Variables323680
Node: Command Line Editing324836
Node: Introduction and Notation326507
Node: Readline Interaction328130
Node: Readline Bare Essentials329321
Node: Readline Movement Commands331104
Node: Readline Killing Commands332064
Node: Readline Arguments333982
Node: Searching335026
Node: Readline Init File337212
Node: Readline Init File Syntax338473
Node: Conditional Init Constructs359753
Node: Sample Init File363949
Node: Bindable Readline Commands367073
Node: Commands For Moving368277
Node: Commands For History370328
Node: Commands For Text375322
Node: Commands For Killing378971
Node: Numeric Arguments382004
Node: Commands For Completion383143
Node: Keyboard Macros387334
Node: Miscellaneous Commands388021
Node: Readline vi Mode393960
Node: Programmable Completion394867
Node: Programmable Completion Builtins402647
Node: A Programmable Completion Example413342
Node: Using History Interactively418589
Node: Bash History Facilities419273
Node: Bash History Builtins422278
Node: History Interaction427286
Node: Event Designators430906
Node: Word Designators432260
Node: Modifiers434020
Node: Installing Bash435831
Node: Basic Installation436968
Node: Compilers and Options440226
Node: Compiling For Multiple Architectures440967
Node: Installation Names442660
Node: Specifying the System Type443478
Node: Sharing Defaults444194
Node: Operation Controls444867
Node: Optional Features445825
Node: Reporting Bugs456625
Node: Major Differences From The Bourne Shell457900
Node: GNU Free Documentation License474750
Node: Indexes499927
Node: Builtin Index500381
Node: Reserved Word Index507208
Node: Variable Index509656
Node: Function Index526148
Node: Concept Index539932

End Tag Table
doc/bashref.texi
+92 -8
View File
@@ -2156,6 +2156,12 @@ If @var{parameter} is unset or null, the expansion of
@var{word} is substituted. Otherwise, the value of
@var{parameter} is substituted.
@example
$ v=123
$ echo $@{v-unset@}
123
@end example
@item $@{@var{parameter}:=@var{word}@}
If @var{parameter}
is unset or null, the expansion of @var{word}
@@ -2164,6 +2170,13 @@ The value of @var{parameter} is then substituted.
Positional parameters and special parameters may not be assigned to
in this way.
@example
$ var=
$ : $@{var:=DEFAULT@}
$ echo $var
DEFAULT
@end example
@item $@{@var{parameter}:?@var{word}@}
If @var{parameter}
is null or unset, the expansion of @var{word} (or a message
@@ -2172,11 +2185,23 @@ is not present) is written to the standard error and the shell, if it
is not interactive, exits. Otherwise, the value of @var{parameter} is
substituted.
@example
$ var=
$ : $@{var:?var is unset or null@}
bash: var: var is unset or null
@end example
@item $@{@var{parameter}:+@var{word}@}
If @var{parameter}
is null or unset, nothing is substituted, otherwise the expansion of
@var{word} is substituted.
@example
$ var=123
$ echo $@{var:+var is set and not null@}
var is set and not null
@end example
@item $@{@var{parameter}:@var{offset}@}
@itemx $@{@var{parameter}:@var{offset}:@var{length}@}
This is referred to as Substring Expansion.
@@ -2389,21 +2414,78 @@ the pattern removal operation is applied to each member of the
array in turn, and the expansion is the resultant list.
@item $@{@var{parameter}/@var{pattern}/@var{string}@}
@itemx $@{@var{parameter}//@var{pattern}/@var{string}@}
@itemx $@{@var{parameter}/#@var{pattern}/@var{string}@}
@itemx $@{@var{parameter}/%@var{pattern}/@var{string}@}
The @var{pattern} is expanded to produce a pattern just as in
filename expansion.
@var{Parameter} is expanded and the longest match of @var{pattern}
against its value is replaced with @var{string}.
@var{string} undergoes tilde expansion, parameter and variable expansion,
arithmetic expansion, command and process substitution, and quote removal.
The match is performed according to the rules described below
(@pxref{Pattern Matching}).
If @var{pattern} begins with @samp{/}, all matches of @var{pattern} are
replaced with @var{string}. Normally only the first match is replaced.
If @var{pattern} begins with @samp{#}, it must match at the beginning
of the expanded value of @var{parameter}.
If @var{pattern} begins with @samp{%}, it must match at the end
of the expanded value of @var{parameter}.
If @var{string} is null, matches of @var{pattern} are deleted
In the first form above, only the first match is replaced.
If there are two slashes separating @var{parameter} and @var{pattern}
(the second form above), all matches of @var{pattern} are
replaced with @var{string}.
If @var{pattern} is preceded by @samp{#} (the third form above),
it must match at the beginning of the expanded value of @var{parameter}.
If @var{pattern} is preceded by @samp{%} (the fourth form above),
it must match at the end of the expanded value of @var{parameter}.
If the expansion of @var{string} is null,
matches of @var{pattern} are deleted.
If @var{string} is null,
matches of @var{pattern} are deleted
and the @samp{/} following @var{pattern} may be omitted.
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
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}.
For instance,
@example
var=abcdef
echo $@{var/abc/& @}
echo "$@{var/abc/& @}"
echo $@{var/abc/"& "@}
@end example
@noindent
will display three lines of "abc def", while
@example
var=abcdef
echo $@{var/abc/\& @}
echo "$@{var/abc/\& @}"
echo $@{var/abc/"\& "@}
@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.
It should rarely be necessary to enclose only @var{string} in double
quotes.
If the @code{nocasematch} shell option
(see the description of @code{shopt} in @ref{The Shopt Builtin})
is enabled, the match is performed without regard to the case
@@ -2426,6 +2508,7 @@ filename expansion.
Each character in the expanded value of @var{parameter} is tested against
@var{pattern}, and, if it matches the pattern, its case is converted.
The pattern should not attempt to match more than one character.
The @samp{^} operator converts lowercase letters matching @var{pattern}
to uppercase; the @samp{,} operator converts matching uppercase letters
to lowercase.
@@ -2434,6 +2517,7 @@ expanded value; the @samp{^} and @samp{,} expansions match and convert only
the first character in the expanded value.
If @var{pattern} is omitted, it is treated like a @samp{?}, which matches
every character.
If @var{parameter} is @samp{@@} or @samp{*},
the case modification operation is applied to each positional
parameter in turn, and the expansion is the resultant list.
doc/builtins.1
+5 -5
View File
@@ -7,14 +7,14 @@
.de FN
\fI\|\\$1\|\fP
..
.TH BASH_BUILTINS 1 "2004 Apr 20" "GNU Bash 5.0"
.TH BASH_BUILTINS 1 "2021 September 30" "GNU Bash 5.1"
.SH NAME
bash, :, ., [, alias, bg, bind, break, builtin, caller,
cd, command, compgen, complete,
compopt, continue, declare, dirs, disown, echo, enable, eval, exec, exit,
:, ., [, alias, bg, bind, break, builtin, caller,
cd, command, compgen, complete, compopt,
continue, declare, dirs, disown, echo, enable, eval, exec, exit,
export, false, fc, fg, getopts, hash, help, history, jobs, kill,
let, local, logout, mapfile, popd, printf, pushd, pwd, read,
readonly, return, set,
readarray, readonly, return, set,
shift, shopt, source, suspend, test, times, trap, true, type, typeset,
ulimit, umask, unalias, unset, wait \- bash built-in commands, see \fBbash\fR(1)
.SH BASH BUILTIN COMMANDS
doc/version.texi
+3 -3
View File
@@ -2,10 +2,10 @@
Copyright (C) 1988-2021 Free Software Foundation, Inc.
@end ignore
@set LASTCHANGE Mon Aug 23 10:07:59 EDT 2021
@set LASTCHANGE Fri Oct 1 15:32:14 EDT 2021
@set EDITION 5.1
@set VERSION 5.1
@set UPDATED 23 August 2021
@set UPDATED-MONTH August 2021
@set UPDATED 1 October 2021
@set UPDATED-MONTH October 2021