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<a name="Input-Section-Wildcards"></a>
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<p>
Next: <a href="Input-Section-Common.html#Input-Section-Common" accesskey="n" rel="next">Input Section Common</a>, Previous: <a href="Input-Section-Basics.html#Input-Section-Basics" accesskey="p" rel="prev">Input Section Basics</a>, Up: <a href="Input-Section.html#Input-Section" accesskey="u" rel="up">Input Section</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Input-Section-Wildcard-Patterns"></a>
<h4 class="subsubsection">3.6.4.2 Input Section Wildcard Patterns</h4>
<a name="index-input-section-wildcards"></a>
<a name="index-wildcard-file-name-patterns"></a>
<a name="index-file-name-wildcard-patterns"></a>
<a name="index-section-name-wildcard-patterns"></a>
<p>In an input section description, either the file name or the section
name or both may be wildcard patterns.
</p>
<p>The file name of &lsquo;<samp>*</samp>&rsquo; seen in many examples is a simple wildcard
pattern for the file name.
</p>
<p>The wildcard patterns are like those used by the Unix shell.
</p>
<dl compact="compact">
<dt>&lsquo;<samp>*</samp>&rsquo;</dt>
<dd><p>matches any number of characters
</p></dd>
<dt>&lsquo;<samp>?</samp>&rsquo;</dt>
<dd><p>matches any single character
</p></dd>
<dt>&lsquo;<samp>[<var>chars</var>]</samp>&rsquo;</dt>
<dd><p>matches a single instance of any of the <var>chars</var>; the &lsquo;<samp>-</samp>&rsquo;
character may be used to specify a range of characters, as in
&lsquo;<samp>[a-z]</samp>&rsquo; to match any lower case letter
</p></dd>
<dt>&lsquo;<samp>\</samp>&rsquo;</dt>
<dd><p>quotes the following character
</p></dd>
</dl>

<p>When a file name is matched with a wildcard, the wildcard characters
will not match a &lsquo;<samp>/</samp>&rsquo; character (used to separate directory names on
Unix).  A pattern consisting of a single &lsquo;<samp>*</samp>&rsquo; character is an
exception; it will always match any file name, whether it contains a
&lsquo;<samp>/</samp>&rsquo; or not.  In a section name, the wildcard characters will match
a &lsquo;<samp>/</samp>&rsquo; character.
</p>
<p>File name wildcard patterns only match files which are explicitly
specified on the command line or in an <code>INPUT</code> command.  The linker
does not search directories to expand wildcards.
</p>
<p>If a file name matches more than one wildcard pattern, or if a file name
appears explicitly and is also matched by a wildcard pattern, the linker
will use the first match in the linker script.  For example, this
sequence of input section descriptions is probably in error, because the
<samp>data.o</samp> rule will not be used:
</p><div class="smallexample">
<pre class="smallexample">.data : { *(.data) }
.data1 : { data.o(.data) }
</pre></div>

<a name="index-SORT_005fBY_005fNAME"></a>
<p>Normally, the linker will place files and sections matched by wildcards
in the order in which they are seen during the link.  You can change
this by using the <code>SORT_BY_NAME</code> keyword, which appears before a wildcard
pattern in parentheses (e.g., <code>SORT_BY_NAME(.text*)</code>).  When the
<code>SORT_BY_NAME</code> keyword is used, the linker will sort the files or sections
into ascending order by name before placing them in the output file.
</p>
<a name="index-SORT_005fBY_005fALIGNMENT"></a>
<p><code>SORT_BY_ALIGNMENT</code> is similar to <code>SORT_BY_NAME</code>.
<code>SORT_BY_ALIGNMENT</code> will sort sections into descending order of
alignment before placing them in the output file.  Placing larger
alignments before smaller alignments can reduce the amount of padding
needed.
</p>
<a name="index-SORT_005fBY_005fINIT_005fPRIORITY"></a>
<p><code>SORT_BY_INIT_PRIORITY</code> is also similar to <code>SORT_BY_NAME</code>.
<code>SORT_BY_INIT_PRIORITY</code> will sort sections into ascending
numerical order of the GCC init_priority attribute encoded in the
section name before placing them in the output file.  In
<code>.init_array.NNNNN</code> and <code>.fini_array.NNNNN</code>, <code>NNNNN</code> is
the init_priority.  In <code>.ctors.NNNNN</code> and <code>.dtors.NNNNN</code>,
<code>NNNNN</code> is 65535 minus the init_priority.
</p>
<a name="index-SORT"></a>
<p><code>SORT</code> is an alias for <code>SORT_BY_NAME</code>.
</p>
<p>When there are nested section sorting commands in linker script, there
can be at most 1 level of nesting for section sorting commands.
</p>
<ol>
<li> <code>SORT_BY_NAME</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)).
It will sort the input sections by name first, then by alignment if two
sections have the same name.
</li><li> <code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)).
It will sort the input sections by alignment first, then by name if two
sections have the same alignment.
</li><li> <code>SORT_BY_NAME</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)) is
treated the same as <code>SORT_BY_NAME</code> (wildcard section pattern).
</li><li> <code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern))
is treated the same as <code>SORT_BY_ALIGNMENT</code> (wildcard section pattern).
</li><li> All other nested section sorting commands are invalid.
</li></ol>

<p>When both command-line section sorting option and linker script
section sorting command are used, section sorting command always
takes precedence over the command-line option.
</p>
<p>If the section sorting command in linker script isn&rsquo;t nested, the
command-line option will make the section sorting command to be
treated as nested sorting command.
</p>
<ol>
<li> <code>SORT_BY_NAME</code> (wildcard section pattern ) with
<samp>--sort-sections alignment</samp> is equivalent to
<code>SORT_BY_NAME</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)).
</li><li> <code>SORT_BY_ALIGNMENT</code> (wildcard section pattern) with
<samp>--sort-section name</samp> is equivalent to
<code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)).
</li></ol>

<p>If the section sorting command in linker script is nested, the
command-line option will be ignored.
</p>
<a name="index-SORT_005fNONE"></a>
<p><code>SORT_NONE</code> disables section sorting by ignoring the command-line
section sorting option.
</p>
<p>If you ever get confused about where input sections are going, use the
&lsquo;<samp>-M</samp>&rsquo; linker option to generate a map file.  The map file shows
precisely how input sections are mapped to output sections.
</p>
<p>This example shows how wildcard patterns might be used to partition
files.  This linker script directs the linker to place all &lsquo;<samp>.text</samp>&rsquo;
sections in &lsquo;<samp>.text</samp>&rsquo; and all &lsquo;<samp>.bss</samp>&rsquo; sections in &lsquo;<samp>.bss</samp>&rsquo;.
The linker will place the &lsquo;<samp>.data</samp>&rsquo; section from all files beginning
with an upper case character in &lsquo;<samp>.DATA</samp>&rsquo;; for all other files, the
linker will place the &lsquo;<samp>.data</samp>&rsquo; section in &lsquo;<samp>.data</samp>&rsquo;.
</p><div class="smallexample">
<pre class="smallexample">SECTIONS {
  .text : { *(.text) }
  .DATA : { [A-Z]*(.data) }
  .data : { *(.data) }
  .bss : { *(.bss) }
}
</pre></div>

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Next: <a href="Input-Section-Common.html#Input-Section-Common" accesskey="n" rel="next">Input Section Common</a>, Previous: <a href="Input-Section-Basics.html#Input-Section-Basics" accesskey="p" rel="prev">Input Section Basics</a>, Up: <a href="Input-Section.html#Input-Section" accesskey="u" rel="up">Input Section</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
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