246 lines
12 KiB
HTML
246 lines
12 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using the GNU Compiler Collection (GCC): Directory Options</title>
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<meta name="description" content="Using the GNU Compiler Collection (GCC): Directory Options">
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<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Directory Options">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Invoking-GCC.html#Invoking-GCC" rel="up" title="Invoking GCC">
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<link href="Code-Gen-Options.html#Code-Gen-Options" rel="next" title="Code Gen Options">
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<link href="Link-Options.html#Link-Options" rel="prev" title="Link Options">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Directory-Options"></a>
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<div class="header">
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<p>
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Next: <a href="Code-Gen-Options.html#Code-Gen-Options" accesskey="n" rel="next">Code Gen Options</a>, Previous: <a href="Link-Options.html#Link-Options" accesskey="p" rel="prev">Link Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Options-for-Directory-Search"></a>
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<h3 class="section">3.15 Options for Directory Search</h3>
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<a name="index-directory-options"></a>
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<a name="index-options_002c-directory-search"></a>
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<a name="index-search-path"></a>
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<p>These options specify directories to search for header files, for
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libraries and for parts of the compiler:
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</p>
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<dl compact="compact">
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<dt><code>-I<var>dir</var></code></dt>
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<dd><a name="index-I-1"></a>
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<p>Add the directory <var>dir</var> to the head of the list of directories to be
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searched for header files. This can be used to override a system header
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file, substituting your own version, since these directories are
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searched before the system header file directories. However, you should
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not use this option to add directories that contain vendor-supplied
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system header files (use <samp>-isystem</samp> for that). If you use more than
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one <samp>-I</samp> option, the directories are scanned in left-to-right
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order; the standard system directories come after.
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</p>
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<p>If a standard system include directory, or a directory specified with
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<samp>-isystem</samp>, is also specified with <samp>-I</samp>, the <samp>-I</samp>
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option is ignored. The directory is still searched but as a
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system directory at its normal position in the system include chain.
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This is to ensure that GCC’s procedure to fix buggy system headers and
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the ordering for the <code>include_next</code> directive are not inadvertently changed.
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If you really need to change the search order for system directories,
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use the <samp>-nostdinc</samp> and/or <samp>-isystem</samp> options.
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</p>
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</dd>
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<dt><code>-iplugindir=<var>dir</var></code></dt>
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<dd><a name="index-iplugindir_003d"></a>
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<p>Set the directory to search for plugins that are passed
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by <samp>-fplugin=<var>name</var></samp> instead of
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<samp>-fplugin=<var>path</var>/<var>name</var>.so</samp>. This option is not meant
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to be used by the user, but only passed by the driver.
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</p>
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</dd>
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<dt><code>-iquote<var>dir</var></code></dt>
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<dd><a name="index-iquote-1"></a>
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<p>Add the directory <var>dir</var> to the head of the list of directories to
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be searched for header files only for the case of <code>#include
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"<var>file</var>"</code>; they are not searched for <code>#include <<var>file</var>></code>,
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otherwise just like <samp>-I</samp>.
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</p>
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</dd>
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<dt><code>-L<var>dir</var></code></dt>
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<dd><a name="index-L"></a>
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<p>Add directory <var>dir</var> to the list of directories to be searched
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for <samp>-l</samp>.
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</p>
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</dd>
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<dt><code>-B<var>prefix</var></code></dt>
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<dd><a name="index-B"></a>
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<p>This option specifies where to find the executables, libraries,
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include files, and data files of the compiler itself.
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</p>
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<p>The compiler driver program runs one or more of the subprograms
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<code>cpp</code>, <code>cc1</code>, <code>as</code> and <code>ld</code>. It tries
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<var>prefix</var> as a prefix for each program it tries to run, both with and
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without ‘<samp><var>machine</var>/<var>version</var>/</samp>’ for the corresponding target
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machine and compiler version.
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</p>
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<p>For each subprogram to be run, the compiler driver first tries the
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<samp>-B</samp> prefix, if any. If that name is not found, or if <samp>-B</samp>
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is not specified, the driver tries two standard prefixes,
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<samp>/usr/lib/gcc/</samp> and <samp>/usr/local/lib/gcc/</samp>. If neither of
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those results in a file name that is found, the unmodified program
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name is searched for using the directories specified in your
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<code>PATH</code> environment variable.
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</p>
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<p>The compiler checks to see if the path provided by <samp>-B</samp>
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refers to a directory, and if necessary it adds a directory
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separator character at the end of the path.
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</p>
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<p><samp>-B</samp> prefixes that effectively specify directory names also apply
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to libraries in the linker, because the compiler translates these
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options into <samp>-L</samp> options for the linker. They also apply to
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include files in the preprocessor, because the compiler translates these
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options into <samp>-isystem</samp> options for the preprocessor. In this case,
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the compiler appends ‘<samp>include</samp>’ to the prefix.
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</p>
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<p>The runtime support file <samp>libgcc.a</samp> can also be searched for using
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the <samp>-B</samp> prefix, if needed. If it is not found there, the two
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standard prefixes above are tried, and that is all. The file is left
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out of the link if it is not found by those means.
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</p>
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<p>Another way to specify a prefix much like the <samp>-B</samp> prefix is to use
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the environment variable <code>GCC_EXEC_PREFIX</code>. See <a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>.
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</p>
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<p>As a special kludge, if the path provided by <samp>-B</samp> is
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<samp>[dir/]stage<var>N</var>/</samp>, where <var>N</var> is a number in the range 0 to
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9, then it is replaced by <samp>[dir/]include</samp>. This is to help
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with boot-strapping the compiler.
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</p>
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</dd>
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<dt><code>-no-canonical-prefixes</code></dt>
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<dd><a name="index-no_002dcanonical_002dprefixes"></a>
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<p>Do not expand any symbolic links, resolve references to ‘<samp>/../</samp>’
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or ‘<samp>/./</samp>’, or make the path absolute when generating a relative
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prefix.
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</p>
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</dd>
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<dt><code>--sysroot=<var>dir</var></code></dt>
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<dd><a name="index-sysroot"></a>
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<p>Use <var>dir</var> as the logical root directory for headers and libraries.
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For example, if the compiler normally searches for headers in
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<samp>/usr/include</samp> and libraries in <samp>/usr/lib</samp>, it instead
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searches <samp><var>dir</var>/usr/include</samp> and <samp><var>dir</var>/usr/lib</samp>.
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</p>
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<p>If you use both this option and the <samp>-isysroot</samp> option, then
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the <samp>--sysroot</samp> option applies to libraries, but the
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<samp>-isysroot</samp> option applies to header files.
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</p>
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<p>The GNU linker (beginning with version 2.16) has the necessary support
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for this option. If your linker does not support this option, the
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header file aspect of <samp>--sysroot</samp> still works, but the
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library aspect does not.
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</p>
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</dd>
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<dt><code>--no-sysroot-suffix</code></dt>
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<dd><a name="index-no_002dsysroot_002dsuffix"></a>
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<p>For some targets, a suffix is added to the root directory specified
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with <samp>--sysroot</samp>, depending on the other options used, so that
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headers may for example be found in
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<samp><var>dir</var>/<var>suffix</var>/usr/include</samp> instead of
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<samp><var>dir</var>/usr/include</samp>. This option disables the addition of
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such a suffix.
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</p>
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</dd>
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<dt><code>-I-</code></dt>
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<dd><a name="index-I_002d-1"></a>
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<p>This option has been deprecated. Please use <samp>-iquote</samp> instead for
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<samp>-I</samp> directories before the <samp>-I-</samp> and remove the <samp>-I-</samp>
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option.
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Any directories you specify with <samp>-I</samp> options before the <samp>-I-</samp>
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option are searched only for the case of <code>#include "<var>file</var>"</code>;
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they are not searched for <code>#include <<var>file</var>></code>.
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</p>
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<p>If additional directories are specified with <samp>-I</samp> options after
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the <samp>-I-</samp> option, these directories are searched for all <code>#include</code>
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directives. (Ordinarily <em>all</em> <samp>-I</samp> directories are used
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this way.)
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</p>
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<p>In addition, the <samp>-I-</samp> option inhibits the use of the current
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directory (where the current input file came from) as the first search
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directory for <code>#include "<var>file</var>"</code>. There is no way to
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override this effect of <samp>-I-</samp>. With <samp>-I.</samp> you can specify
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searching the directory that is current when the compiler is
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invoked. That is not exactly the same as what the preprocessor does
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by default, but it is often satisfactory.
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</p>
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<p><samp>-I-</samp> does not inhibit the use of the standard system directories
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for header files. Thus, <samp>-I-</samp> and <samp>-nostdinc</samp> are
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independent.
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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="Code-Gen-Options.html#Code-Gen-Options" accesskey="n" rel="next">Code Gen Options</a>, Previous: <a href="Link-Options.html#Link-Options" accesskey="p" rel="prev">Link Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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