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<h5 class="subsubsection">3.6.4.2 Input Section Wildcard Patterns</h5>

<p><a name="index-input-section-wildcards-399"></a><a name="index-wildcard-file-name-patterns-400"></a><a name="index-file-name-wildcard-patterns-401"></a><a name="index-section-name-wildcard-patterns-402"></a>In an input section description, either the file name or the section
name or both may be wildcard patterns.

   <p>The file name of &lsquo;<samp><span class="samp">*</span></samp>&rsquo; seen in many examples is a simple wildcard
pattern for the file name.

   <p>The wildcard patterns are like those used by the Unix shell.

     <dl>
<dt>&lsquo;<samp><span class="samp">*</span></samp>&rsquo;<dd>matches any number of characters
<br><dt>&lsquo;<samp><span class="samp">?</span></samp>&rsquo;<dd>matches any single character
<br><dt>&lsquo;<samp><span class="samp">[</span><var>chars</var><span class="samp">]</span></samp>&rsquo;<dd>matches a single instance of any of the <var>chars</var>; the &lsquo;<samp><span class="samp">-</span></samp>&rsquo;
character may be used to specify a range of characters, as in
&lsquo;<samp><span class="samp">[a-z]</span></samp>&rsquo; to match any lower case letter
<br><dt>&lsquo;<samp><span class="samp">\</span></samp>&rsquo;<dd>quotes the following character
</dl>

   <p>When a file name is matched with a wildcard, the wildcard characters
will not match a &lsquo;<samp><span class="samp">/</span></samp>&rsquo; character (used to separate directory names on
Unix).  A pattern consisting of a single &lsquo;<samp><span class="samp">*</span></samp>&rsquo; character is an
exception; it will always match any file name, whether it contains a
&lsquo;<samp><span class="samp">/</span></samp>&rsquo; or not.  In a section name, the wildcard characters will match
a &lsquo;<samp><span class="samp">/</span></samp>&rsquo; character.

   <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>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><span class="file">data.o</span></samp> rule will not be used:
<pre class="smallexample">     .data : { *(.data) }
     .data1 : { data.o(.data) }
</pre>
   <p><a name="index-SORT_005fBY_005fNAME-403"></a>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-404"></a><code>SORT_BY_ALIGNMENT</code> is very similar to <code>SORT_BY_NAME</code>. The
difference is <code>SORT_BY_ALIGNMENT</code> will sort sections into
ascending order by alignment before placing them in the output file.

   <p><a name="index-SORT-405"></a><code>SORT</code> is an alias for <code>SORT_BY_NAME</code>.

   <p>When there are nested section sorting commands in linker script, there
can be at most 1 level of nesting for section sorting commands.

     <ol type=1 start=1>
<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 2
sections have the same name. 
<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 2
sections have the same alignment. 
<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><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>All other nested section sorting commands are invalid.
        </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>If the section sorting command in linker script isn't nested, the
command line option will make the section sorting command to be
treated as nested sorting command.

     <ol type=1 start=1>
<li><code>SORT_BY_NAME</code> (wildcard section pattern ) with
<samp><span class="option">--sort-sections alignment</span></samp> is equivalent to
<code>SORT_BY_NAME</code> (<code>SORT_BY_ALIGNMENT</code> (wildcard section pattern)). 
<li><code>SORT_BY_ALIGNMENT</code> (wildcard section pattern) with
<samp><span class="option">--sort-section name</span></samp> is equivalent to
<code>SORT_BY_ALIGNMENT</code> (<code>SORT_BY_NAME</code> (wildcard section pattern)).
        </ol>

   <p>If the section sorting command in linker script is nested, the
command line option will be ignored.

   <p>If you ever get confused about where input sections are going, use the
&lsquo;<samp><span class="samp">-M</span></samp>&rsquo; linker option to generate a map file.  The map file shows
precisely how input sections are mapped to output sections.

   <p>This example shows how wildcard patterns might be used to partition
files.  This linker script directs the linker to place all &lsquo;<samp><span class="samp">.text</span></samp>&rsquo;
sections in &lsquo;<samp><span class="samp">.text</span></samp>&rsquo; and all &lsquo;<samp><span class="samp">.bss</span></samp>&rsquo; sections in &lsquo;<samp><span class="samp">.bss</span></samp>&rsquo;. 
The linker will place the &lsquo;<samp><span class="samp">.data</span></samp>&rsquo; section from all files beginning
with an upper case character in &lsquo;<samp><span class="samp">.DATA</span></samp>&rsquo;; for all other files, the
linker will place the &lsquo;<samp><span class="samp">.data</span></samp>&rsquo; section in &lsquo;<samp><span class="samp">.data</span></samp>&rsquo;.
<pre class="smallexample">     SECTIONS {
       .text : { *(.text) }
       .DATA : { [A-Z]*(.data) }
       .data : { *(.data) }
       .bss : { *(.bss) }
     }
</pre>
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