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diff --git a/doc/bashref.html b/doc/bashref.html index c0496399..fea2ed77 100644 --- a/doc/bashref.html +++ b/doc/bashref.html @@ -4,9 +4,9 @@ <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!-- This text is a brief description of the features that are present in -the Bash shell (version 5.2, 17 April 2023). +the Bash shell (version 5.2, 14 May 2023). -This is Edition 5.2, last updated 17 April 2023, +This is Edition 5.2, last updated 14 May 2023, of The GNU Bash Reference Manual, for Bash, Version 5.2. @@ -77,10 +77,10 @@ Next: <a href="#Introduction" accesskey="n" rel="next">Introduction</a>, Previou <span id="Bash-Features-1"></span><h1 class="top">Bash Features</h1> <p>This text is a brief description of the features that are present in -the Bash shell (version 5.2, 17 April 2023). +the Bash shell (version 5.2, 14 May 2023). The Bash home page is <a href="http://www.gnu.org/software/bash/">http://www.gnu.org/software/bash/</a>. </p> -<p>This is Edition 5.2, last updated 17 April 2023, +<p>This is Edition 5.2, last updated 14 May 2023, of <cite>The GNU Bash Reference Manual</cite>, for <code>Bash</code>, Version 5.2. </p> @@ -737,8 +737,8 @@ Next: <a href="#Locale-Translation" accesskey="n" rel="next">Locale-Specific Tra <span id="ANSI_002dC-Quoting-1"></span><h4 class="subsubsection">3.1.2.4 ANSI-C Quoting</h4> <span id="index-quoting_002c-ANSI"></span> -<p>Character sequences of the form $’<var>string</var>’ are treated as a special -kind of single quotes. +<p>Character sequences of the form <code>$'<var>string</var>'</code> are treated as +a special kind of single quotes. The sequence expands to <var>string</var>, with backslash-escaped characters in <var>string</var> replaced as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows: @@ -3049,24 +3049,25 @@ Next: <a href="#Arithmetic-Expansion" accesskey="n" rel="next">Arithmetic Expans <p>Command substitution allows the output of a command to replace the command itself. -Command substitution occurs when a command is enclosed as follows: +The standard form of command substitution occurs when a command is +enclosed as follows: </p><div class="example"> <pre class="example">$(<var>command</var>) </pre></div> -<p>or +<p>or (deprecated) </p><div class="example"> -<pre class="example">`<var>command</var>` +<pre class="example">`<var>command</var>`. </pre></div> -<p>Bash performs the expansion by executing <var>command</var> in a subshell environment -and replacing the command substitution with the standard output of the -command, with any trailing newlines deleted. +<p>Bash performs the expansion by executing <var>command</var> in a subshell +environment and replacing the command substitution with the standard +output of the command, with any trailing newlines deleted. Embedded newlines are not deleted, but they may be removed during word splitting. The command substitution <code>$(cat <var>file</var>)</code> can be replaced by the equivalent but faster <code>$(< <var>file</var>)</code>. </p> -<p>When the old-style backquote form of substitution is used, +<p>With the old-style backquote form of substitution, backslash retains its literal meaning except when followed by ‘<samp>$</samp>’, ‘<samp>`</samp>’, or ‘<samp>\</samp>’. The first backquote not preceded by a backslash terminates the @@ -3074,11 +3075,70 @@ command substitution. When using the <code>$(<var>command</var>)</code> form, all characters between the parentheses make up the command; none are treated specially. </p> +<p>There is an alternate form of command substitution: +</p> +<div class="example"> +<pre class="example">${<var>C</var> <var>command</var>; } +</pre></div> + +<p>which executes <var>command</var> in the current execution environment. +This means that side effects of <var>command</var> take effect immediately +in the current execution environment and persist in the current +environment after the command completes (e.g., the <code>exit</code> builtin +will exit the shell). +</p> +<p>The character <var>C</var> following the open brace must be a space, tab, +newline, ‘<samp>(</samp>’, or ‘<samp>|</samp>’, and the close brace must be in a position +where a reserved word may appear (i.e., preceded by a command terminator +such as semicolon). +Bash allows the close brace to be joined to the remaining characters in +the word without being followed by a shell metacharacter as a reserved +word would usually require. +</p> +<p>This type of command substitution superficially resembles executing an +unnamed shell function: local variables are created as when a shell +function is executing, and the <code>return</code> builtin forces +<var>command</var> to complete; +however, the rest of the execution environment, +including the positional parameters, is shared with the caller. +</p> +<p>If the first character following the open brace is a ‘<samp>(</samp>’, +<var>command</var> is executed in a subshell, and <var>command</var> must be +terminated by a ‘<samp>)</samp>’. This is similar to the <code>(</code> compound +command (see <a href="#Command-Grouping">Grouping Commands</a>). +If the first character is a ‘<samp>|</samp>’, the construct expands to the +value of the <code>REPLY</code> shell variable after <var>command</var> executes, +without removing any trailing newlines, +and the standard output of <var>command</var> remains the same as in the +calling shell. +Bash creates <code>REPLY</code> as an initially-unset local variable when +<var>command</var> executes, and restores <code>REPLY</code> to the value it had +before the command substitution after <var>command</var> completes, +as with any local variable. +</p> +<p>For example, this construct expands to ‘<samp>12345</samp>’, and leaves the +shell variable <code>X</code> unchanged in the current execution environment: +</p> +<div class="example"> +<pre class="example">${ local X=12345 ; echo $X; } +</pre></div> + +<p>(not declaring <code>X</code> as local would modify its value in the current +environment, as with normal shell function execution), +while this construct does not require any output to expand to +‘<samp>12345</samp>’: +</p> +<div class="example"> +<pre class="example">${| REPLY=12345; } +</pre></div> + +<p>and restores <code>REPLY</code> to the value it had before the command substitution. +</p> <p>Command substitutions may be nested. To nest when using the backquoted form, escape the inner backquotes with backslashes. </p> -<p>If the substitution appears within double quotes, word splitting and -filename expansion are not performed on the results. +<p>If the substitution appears within double quotes, Bash does not perform +word splitting and filename expansion on the results. </p> <hr> </div> @@ -7294,6 +7354,9 @@ inode change time, and number of blocks, respectively. <p>For example, a value of <code>-mtime</code> sorts the results in descending order by modification time (newest first). </p> +<p>A sort specifier of ‘<samp>nosort</samp>’ disables sorting completely; the results +are returned in the order they are read from the file system,. +</p> <p>If the sort specifier is missing, it defaults to <var>name</var>, so a value of ‘<samp>+</samp>’ is equivalent to the null string, and a value of ‘<samp>-</samp>’ sorts by name in descending order. @@ -9656,16 +9719,6 @@ has no special effect </li></ul> </dd> -<dt><span><code>compat32</code></span></dt> -<dd><ul> -<li> interrupting a command list such as "a ; b ; c" causes the execution -of the next command in the list (in bash-4.0 and later versions, -the shell acts as if it received the interrupt, so -interrupting one command in a list aborts the execution of the -entire list) -</li></ul> - -</dd> <dt><span><code>compat40</code></span></dt> <dd><ul> <li> the ‘<samp><</samp>’ and ‘<samp>></samp>’ operators to the <code>[[</code> command do not |