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next set of documentation updates (word splitting), rearrange a test in readline's tilde expansion to avoid touching uninitialized data

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Chet Ramey
2024-10-22 15:40:46 -04:00
parent 261c6e8cc6
commit 474743f2da
21 changed files with 4581 additions and 4506 deletions
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doc/bashref.html
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@@ -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 5.3, 15 October 2024).
the Bash shell (version 5.3, 20 October 2024).
This is Edition 5.3, last updated 15 October 2024,
This is Edition 5.3, last updated 20 October 2024,
of The GNU Bash Reference Manual,
for Bash, Version 5.3.
@@ -77,10 +77,10 @@ Next: <a href="#Introduction" accesskey="n" rel="next">Introduction</a>, Previou
<h1 class="top" id="Bash-Features-1"><span>Bash Features<a class="copiable-link" href="#Bash-Features-1"> &para;</a></span></h1>
<p>This text is a brief description of the features that are present in
the Bash shell (version 5.3, 15 October 2024).
the Bash shell (version 5.3, 20 October 2024).
The Bash home page is <a class="url" href="http://www.gnu.org/software/bash/">http://www.gnu.org/software/bash/</a>.
</p>
<p>This is Edition 5.3, last updated 15 October 2024,
<p>This is Edition 5.3, last updated 20 October 2024,
of <cite class="cite">The GNU Bash Reference Manual</cite>,
for <code class="code">Bash</code>, Version 5.3.
</p>
@@ -430,6 +430,11 @@ is primarily concerned with the Shell and Utilities portion of the
<dd><p>A space or tab character.
</p>
</dd>
<dt><code class="code">whitespace</code></dt>
<dd><p>A character belonging to the <code class="code">space</code> character class in the
current locale, or for which <code class="code">isspace()</code> returns true.
</p>
</dd>
<dt><a id="index-builtin-1"></a><span><code class="code">builtin</code><a class="copiable-link" href="#index-builtin-1"> &para;</a></span></dt>
<dd><p>A command that is implemented internally by the shell itself, rather
than by an executable program somewhere in the file system.
@@ -3329,45 +3334,54 @@ Next: <a href="#Filename-Expansion" accesskey="n" rel="next">Filename Expansion<
<p>The shell scans the results of parameter expansion, command substitution,
and arithmetic expansion that did not occur within double quotes for
word splitting.
Words that were not expanded are not split.
</p>
<p>The shell treats each character of <code class="env">$IFS</code> as a delimiter, and splits
the results of the other expansions into words using these characters
as field terminators.
<p>The shell treats each character of <code class="env">$IFS</code> as a delimiter,
and splits the results of the other expansions into fields
using these characters as field terminators.
</p>
<p>If <code class="env">IFS</code> is unset, or its value is exactly <code class="code">&lt;space&gt;&lt;tab&gt;&lt;newline&gt;</code>,
the default, then sequences of
<code class="code">space</code>, <code class="code">tab</code>, and <code class="code">newline</code>
at the beginning and end of the results of the previous
expansions are ignored, and any sequence of <code class="env">IFS</code>
characters not at the beginning or end delimits words.
If <code class="env">IFS</code> has a value other than the default, then sequences of
the whitespace characters <code class="code">space</code>, <code class="code">tab</code>, and <code class="code">newline</code>
present the value of <code class="env">IFS</code> (an <code class="env">IFS</code> whitespace character)
are ignored at the beginning and end of the word.
Any character in <code class="env">IFS</code> that is not <code class="env">IFS</code>
whitespace, along with any adjacent <code class="env">IFS</code>
whitespace characters, delimits a field. A sequence of <code class="env">IFS</code>
whitespace characters is also treated as a delimiter.
<p>An <em class="dfn">IFS whitespace</em> character is whitespace as defined above
(see <a class="pxref" href="#Definitions">Definitions</a>) that appears in the value of <code class="env">IFS</code>.
Space, tab, and newline are always considered IFS whitespace, even
if they don&rsquo;t appear in the locale&rsquo;s <code class="code">space</code> category.
</p>
<p>If the value of <code class="env">IFS</code> is null, no word splitting occurs.
If <code class="env">IFS</code> is unset, word splitting behaves as if it contained
the default value <code class="code">&lt;space&gt;&lt;tab&gt;&lt;newline&gt;</code>.
<p>If <code class="env">IFS</code> is unset, word splitting behaves as if its value were
<code class="code">&lt;space&gt;&lt;tab&gt;&lt;newline&gt;</code>,
and treats these characters as IFS whitespace.
If the value of <code class="env">IFS</code> is null, no word splitting occurs,
but implicit null arguments (see below) are still removed.
</p>
<p>Word splitting begins by removing sequences of IFS whitespace characters
from the beginning and end of the results of the previous expansions,
then splits the remaining words.
</p>
<p>If the value of <code class="env">IFS</code> consists solely of IFS whitespace,
any sequence of IFS whitespace characters delimits a field,
so a field consists of characters that are not unquoted IFS
whitespace, and null fields result only from quoting.
</p>
<p>If <code class="env">IFS</code> contains a non-whitespace character, then any
character in the value of <code class="env">IFS</code> that is not IFS whitespace,
along with any adjacent IFS whitespace characters, delimits a field.
This means that adjacent non-IFS-whitespace delimiters produce a
null field.
A sequence of IFS whitespace characters also delimits a field.
</p>
<p>Explicit null arguments (<code class="code">&quot;&quot;</code> or <code class="code">''</code>) are retained
and passed to commands as empty strings.
Unquoted implicit null arguments, resulting from the expansion of
parameters that have no values, are removed.
If a parameter with no value is expanded within double quotes, a
null argument results and is retained
and passed to a command as an empty string.
When a quoted null argument appears as part of a word whose expansion is
non-null, the null argument is removed.
Expanding a parameter with no value within double quotes
produces a null field,
which is retained and passed to a command as an empty string.
</p>
<p>When a quoted null argument appears as part of a word whose expansion
is non-null, word splitting removes the null argument portion,
leaving the non-null expansion.
That is, the word
<code class="code">-d''</code> becomes <code class="code">-d</code> after word splitting and
null argument removal.
</p>
<p>Note that if no expansion occurs, no splitting is performed.
</p>
<hr>
</div>
<div class="subsection-level-extent" id="Filename-Expansion">