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<title>LD: File Commands</title>
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<a name="File-Commands"></a>
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<div class="header">
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<p>
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Next: <a href="Format-Commands.html#Format-Commands" accesskey="n" rel="next">Format Commands</a>, Previous: <a href="Entry-Point.html#Entry-Point" accesskey="p" rel="previous">Entry Point</a>, Up: <a href="Simple-Commands.html#Simple-Commands" accesskey="u" rel="up">Simple Commands</a> [<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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</div>
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<hr>
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<a name="Commands-Dealing-with-Files"></a>
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<h4 class="subsection">3.4.2 Commands Dealing with Files</h4>
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<a name="index-linker-script-file-commands"></a>
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<p>Several linker script commands deal with files.
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</p>
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<dl compact="compact">
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<dt><code>INCLUDE <var>filename</var></code></dt>
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<dd><a name="index-INCLUDE-filename"></a>
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<a name="index-including-a-linker-script"></a>
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<p>Include the linker script <var>filename</var> at this point. The file will
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be searched for in the current directory, and in any directory specified
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with the <samp>-L</samp> option. You can nest calls to <code>INCLUDE</code> up to
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10 levels deep.
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</p>
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<p>You can place <code>INCLUDE</code> directives at the top level, in <code>MEMORY</code> or
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<code>SECTIONS</code> commands, or in output section descriptions.
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</p>
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</dd>
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<dt><code>INPUT(<var>file</var>, <var>file</var>, …)</code></dt>
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<dt><code>INPUT(<var>file</var> <var>file</var> …)</code></dt>
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<dd><a name="index-INPUT_0028files_0029"></a>
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<a name="index-input-files-in-linker-scripts"></a>
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<a name="index-input-object-files-in-linker-scripts"></a>
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<a name="index-linker-script-input-object-files"></a>
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<p>The <code>INPUT</code> command directs the linker to include the named files
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in the link, as though they were named on the command line.
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</p>
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<p>For example, if you always want to include <samp>subr.o</samp> any time you do
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a link, but you can’t be bothered to put it on every link command line,
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then you can put ‘<samp>INPUT (subr.o)</samp>’ in your linker script.
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</p>
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<p>In fact, if you like, you can list all of your input files in the linker
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script, and then invoke the linker with nothing but a ‘<samp>-T</samp>’ option.
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</p>
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<p>In case a <em>sysroot prefix</em> is configured, and the filename starts
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with the ‘<samp>/</samp>’ character, and the script being processed was
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located inside the <em>sysroot prefix</em>, the filename will be looked
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for in the <em>sysroot prefix</em>. The <em>sysroot prefix</em> can also be forced by specifying
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<code>=</code> as the first character in the filename path, or prefixing the
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filename path with <code>$SYSROOT</code>. See also the description of
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‘<samp>-L</samp>’ in <a href="Options.html#Options">Command-line Options</a>.
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</p>
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<p>If a <em>sysroot prefix</em> is not used then the linker will try to open
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the file in the directory containing the linker script. If it is not
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found the linker will then search the current directory. If it is still
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not found the linker will search through the archive library search
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path.
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</p>
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<p>If you use ‘<samp>INPUT (-l<var>file</var>)</samp>’, <code>ld</code> will transform the
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name to <code>lib<var>file</var>.a</code>, as with the command-line argument
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‘<samp>-l</samp>’.
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</p>
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<p>When you use the <code>INPUT</code> command in an implicit linker script, the
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files will be included in the link at the point at which the linker
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script file is included. This can affect archive searching.
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</p>
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</dd>
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<dt><code>GROUP(<var>file</var>, <var>file</var>, …)</code></dt>
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<dt><code>GROUP(<var>file</var> <var>file</var> …)</code></dt>
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<dd><a name="index-GROUP_0028files_0029"></a>
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<a name="index-grouping-input-files"></a>
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<p>The <code>GROUP</code> command is like <code>INPUT</code>, except that the named
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files should all be archives, and they are searched repeatedly until no
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new undefined references are created. See the description of ‘<samp>-(</samp>’
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in <a href="Options.html#Options">Command-line Options</a>.
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</p>
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</dd>
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<dt><code>AS_NEEDED(<var>file</var>, <var>file</var>, …)</code></dt>
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<dt><code>AS_NEEDED(<var>file</var> <var>file</var> …)</code></dt>
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<dd><a name="index-AS_005fNEEDED_0028files_0029"></a>
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<p>This construct can appear only inside of the <code>INPUT</code> or <code>GROUP</code>
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commands, among other filenames. The files listed will be handled
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as if they appear directly in the <code>INPUT</code> or <code>GROUP</code> commands,
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with the exception of ELF shared libraries, that will be added only
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when they are actually needed. This construct essentially enables
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<samp>--as-needed</samp> option for all the files listed inside of it
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and restores previous <samp>--as-needed</samp> resp. <samp>--no-as-needed</samp>
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setting afterwards.
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</p>
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</dd>
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<dt><code>OUTPUT(<var>filename</var>)</code></dt>
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<dd><a name="index-OUTPUT_0028filename_0029"></a>
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<a name="index-output-file-name-in-linker-script"></a>
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<p>The <code>OUTPUT</code> command names the output file. Using
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<code>OUTPUT(<var>filename</var>)</code> in the linker script is exactly like using
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‘<samp>-o <var>filename</var></samp>’ on the command line (see <a href="Options.html#Options">Command
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Line Options</a>). If both are used, the command-line option takes
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precedence.
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</p>
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<p>You can use the <code>OUTPUT</code> command to define a default name for the
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output file other than the usual default of <samp>a.out</samp>.
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</p>
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</dd>
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<dt><code>SEARCH_DIR(<var>path</var>)</code></dt>
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<dd><a name="index-SEARCH_005fDIR_0028path_0029"></a>
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<a name="index-library-search-path-in-linker-script"></a>
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<a name="index-archive-search-path-in-linker-script"></a>
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<a name="index-search-path-in-linker-script"></a>
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<p>The <code>SEARCH_DIR</code> command adds <var>path</var> to the list of paths where
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<code>ld</code> looks for archive libraries. Using
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<code>SEARCH_DIR(<var>path</var>)</code> is exactly like using ‘<samp>-L <var>path</var></samp>’
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on the command line (see <a href="Options.html#Options">Command-line Options</a>). If both
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are used, then the linker will search both paths. Paths specified using
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the command-line option are searched first.
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</p>
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</dd>
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<dt><code>STARTUP(<var>filename</var>)</code></dt>
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<dd><a name="index-STARTUP_0028filename_0029"></a>
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<a name="index-first-input-file"></a>
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<p>The <code>STARTUP</code> command is just like the <code>INPUT</code> command, except
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that <var>filename</var> will become the first input file to be linked, as
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though it were specified first on the command line. This may be useful
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when using a system in which the entry point is always the start of the
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first file.
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</p></dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Format-Commands.html#Format-Commands" accesskey="n" rel="next">Format Commands</a>, Previous: <a href="Entry-Point.html#Entry-Point" accesskey="p" rel="previous">Entry Point</a>, Up: <a href="Simple-Commands.html#Simple-Commands" accesskey="u" rel="up">Simple Commands</a> [<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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