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fixes to read/wait; revert change that processes $'...' quoting in here-documents unconditionally
This commit is contained in:
Chet Ramey
+48
-28
@@ -4,9 +4,9 @@
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This text is a brief description of the features that are present in
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the Bash shell (version 5.2, 26 December 2021).
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the Bash shell (version 5.2, 17 January 2022).
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This is Edition 5.2, last updated 26 December 2021,
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This is Edition 5.2, last updated 17 January 2022,
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of The GNU Bash Reference Manual,
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for Bash, Version 5.2.
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@@ -77,10 +77,10 @@ Next: <a href="#Introduction" accesskey="n" rel="next">Introduction</a>, Previou
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<span id="Bash-Features-1"></span><h1 class="top">Bash Features</h1>
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<p>This text is a brief description of the features that are present in
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the Bash shell (version 5.2, 26 December 2021).
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the Bash shell (version 5.2, 17 January 2022).
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The Bash home page is <a href="http://www.gnu.org/software/bash/">http://www.gnu.org/software/bash/</a>.
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</p>
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<p>This is Edition 5.2, last updated 26 December 2021,
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<p>This is Edition 5.2, last updated 17 January 2022,
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of <cite>The GNU Bash Reference Manual</cite>,
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for <code>Bash</code>, Version 5.2.
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</p>
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@@ -2845,45 +2845,65 @@ and the ‘<samp>/</samp>’ following <var>pattern</var> may be omitted
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any unquoted instances of ‘<samp>&</samp>’ in <var>string</var> are replaced with the
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matching portion of <var>pattern</var>.
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This is intended to duplicate a common <code>sed</code> idiom.
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Backslash is used to quote ‘<samp>&</samp>’ in <var>string</var>; the backslash is removed
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</p>
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<p>Quoting any part of <var>string</var> 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 ‘<samp>&</samp>’ in <var>string</var>; the backslash is removed
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in order to permit a literal ‘<samp>&</samp>’ in the replacement string.
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Pattern substitution performs the check for ‘<samp>&</samp>’ after expanding
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<var>string</var>,
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so users should take care to quote backslashes intended to escape
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the ‘<samp>&</samp>’ and inhibit replacement so they survive any quote removal
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performed by the expansion of <var>string</var>.
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For instance,
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Users should take care if <var>string</var> is double-quoted to avoid
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unwanted interactions between the backslash and double-quoting, since
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backslash has special meaning within double quotes.
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Pattern substitution performs the check for unquoted ‘<samp>&</samp>’ after
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expanding <var>string</var>,
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so users should ensure to properly quote any occurrences of ‘<samp>&</samp>’
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they want to be taken literally in the replacement
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and ensure any instances of ‘<samp>&</samp>’ they want to be replaced are unquoted.
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</p>
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<p>For instance,
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</p>
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<div class="example">
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<pre class="example">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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</pre></div>
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<p>will display three lines of "abc def", while
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<p>will display four lines of "abc def", while
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</p>
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<div class="example">
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<pre class="example">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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</pre></div>
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<p>will display two lines of "abc def" and a third line of "& def".
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The first two are replaced because the backslash is removed by quote
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removal performed during the expansion of <var>string</var>
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(the expansion is performed in a
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context that doesn’t take any enclosing double quotes into account, as
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with other word expansions).
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In the third case, the double quotes affect the expansion
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of ‘<samp>\&</samp>’, and, because ‘<samp>&</samp>’ is not one of the characters for
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which backslash is special in double quotes,
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the backslash survives the expansion, inhibits the replacement,
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but is removed because it is treated specially.
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One could use ‘<samp>\\&</samp>’, unquoted, as the replacement string to achive
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the same effect.
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It should rarely be necessary to enclose only <var>string</var> in double
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<p>will display four lines of "& def".
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Like the pattern removal operators, double quotes surrounding the
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replacement string quote the expanded characters, while double quotes
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enclosing the entire parameter substitution do not, since
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the expansion is performed in a
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context that doesn’t take any enclosing double quotes into account.
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</p>
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<p>Since backslash can escape ‘<samp>&</samp>’, it can also escape a backslash in
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the replacement string.
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This means that ‘<samp>\\</samp>’ will insert a literal
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backslash into the replacement, so these two <code>echo</code> commands
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</p>
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<div class="example">
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<pre class="example">var=abcdef
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rep='\\&xyz'
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echo ${var/abc/\\&xyz}
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echo ${var/abc/$rep}
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</pre></div>
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<p>will both output ‘<samp>\abcxyzdef</samp>’.
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</p>
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<p>It should rarely be necessary to enclose only <var>string</var> in double
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quotes.
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</p>
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<p>If the <code>nocasematch</code> shell option
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