1<html lang="en"> 2<head> 3<title>Directory Options - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Invoking-GCC.html#Invoking-GCC" title="Invoking GCC"> 9<link rel="prev" href="Link-Options.html#Link-Options" title="Link Options"> 10<link rel="next" href="Spec-Files.html#Spec-Files" title="Spec Files"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 141998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 152010 Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation; with the 20Invariant Sections being ``Funding Free Software'', the Front-Cover 21Texts being (a) (see below), and with the Back-Cover Texts being (b) 22(see below). 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This can be used to override a system header 67file, substituting your own version, since these directories are 68searched before the system header file directories. However, you should 69not use this option to add directories that contain vendor-supplied 70system header files (use <samp><span class="option">-isystem</span></samp> for that). If you use more than 71one <samp><span class="option">-I</span></samp> option, the directories are scanned in left-to-right 72order; the standard system directories come after. 73 74 <p>If a standard system include directory, or a directory specified with 75<samp><span class="option">-isystem</span></samp>, is also specified with <samp><span class="option">-I</span></samp>, the <samp><span class="option">-I</span></samp> 76option will be ignored. The directory will still be searched but as a 77system directory at its normal position in the system include chain. 78This is to ensure that GCC's procedure to fix buggy system headers and 79the ordering for the include_next directive are not inadvertently changed. 80If you really need to change the search order for system directories, 81use the <samp><span class="option">-nostdinc</span></samp> and/or <samp><span class="option">-isystem</span></samp> options. 82 83 <br><dt><code>-iplugindir=</code><var>dir</var><dd>Set the directory to search for plugins which are passed 84by <samp><span class="option">-fplugin=</span><var>name</var></samp> instead of 85<samp><span class="option">-fplugin=</span><var>path</var><span class="option">/</span><var>name</var><span class="option">.so</span></samp>. This option is not meant 86to be used by the user, but only passed by the driver. 87 88 <br><dt><code>-iquote</code><var>dir</var><dd><a name="index-iquote-1002"></a>Add the directory <var>dir</var> to the head of the list of directories to 89be searched for header files only for the case of ‘<samp><span class="samp">#include 90"</span><var>file</var><span class="samp">"</span></samp>’; they are not searched for ‘<samp><span class="samp">#include <</span><var>file</var><span class="samp">></span></samp>’, 91otherwise just like <samp><span class="option">-I</span></samp>. 92 93 <br><dt><code>-L</code><var>dir</var><dd><a name="index-L-1003"></a>Add directory <var>dir</var> to the list of directories to be searched 94for <samp><span class="option">-l</span></samp>. 95 96 <br><dt><code>-B</code><var>prefix</var><dd><a name="index-B-1004"></a>This option specifies where to find the executables, libraries, 97include files, and data files of the compiler itself. 98 99 <p>The compiler driver program runs one or more of the subprograms 100<samp><span class="file">cpp</span></samp>, <samp><span class="file">cc1</span></samp>, <samp><span class="file">as</span></samp> and <samp><span class="file">ld</span></samp>. It tries 101<var>prefix</var> as a prefix for each program it tries to run, both with and 102without ‘<samp><var>machine</var><span class="samp">/</span><var>version</var><span class="samp">/</span></samp>’ (see <a href="Target-Options.html#Target-Options">Target Options</a>). 103 104 <p>For each subprogram to be run, the compiler driver first tries the 105<samp><span class="option">-B</span></samp> prefix, if any. If that name is not found, or if <samp><span class="option">-B</span></samp> 106was not specified, the driver tries two standard prefixes, which are 107<samp><span class="file">/usr/lib/gcc/</span></samp> and <samp><span class="file">/usr/local/lib/gcc/</span></samp>. If neither of 108those results in a file name that is found, the unmodified program 109name is searched for using the directories specified in your 110<samp><span class="env">PATH</span></samp> environment variable. 111 112 <p>The compiler will check to see if the path provided by the <samp><span class="option">-B</span></samp> 113refers to a directory, and if necessary it will add a directory 114separator character at the end of the path. 115 116 <p><samp><span class="option">-B</span></samp> prefixes that effectively specify directory names also apply 117to libraries in the linker, because the compiler translates these 118options into <samp><span class="option">-L</span></samp> options for the linker. They also apply to 119includes files in the preprocessor, because the compiler translates these 120options into <samp><span class="option">-isystem</span></samp> options for the preprocessor. In this case, 121the compiler appends ‘<samp><span class="samp">include</span></samp>’ to the prefix. 122 123 <p>The run-time support file <samp><span class="file">libgcc.a</span></samp> can also be searched for using 124the <samp><span class="option">-B</span></samp> prefix, if needed. If it is not found there, the two 125standard prefixes above are tried, and that is all. The file is left 126out of the link if it is not found by those means. 127 128 <p>Another way to specify a prefix much like the <samp><span class="option">-B</span></samp> prefix is to use 129the environment variable <samp><span class="env">GCC_EXEC_PREFIX</span></samp>. See <a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>. 130 131 <p>As a special kludge, if the path provided by <samp><span class="option">-B</span></samp> is 132<samp><span class="file">[dir/]stage</span><var>N</var><span class="file">/</span></samp>, where <var>N</var> is a number in the range 0 to 1339, then it will be replaced by <samp><span class="file">[dir/]include</span></samp>. This is to help 134with boot-strapping the compiler. 135 136 <br><dt><code>-specs=</code><var>file</var><dd><a name="index-specs-1005"></a>Process <var>file</var> after the compiler reads in the standard <samp><span class="file">specs</span></samp> 137file, in order to override the defaults that the <samp><span class="file">gcc</span></samp> driver 138program uses when determining what switches to pass to <samp><span class="file">cc1</span></samp>, 139<samp><span class="file">cc1plus</span></samp>, <samp><span class="file">as</span></samp>, <samp><span class="file">ld</span></samp>, etc. More than one 140<samp><span class="option">-specs=</span><var>file</var></samp> can be specified on the command line, and they 141are processed in order, from left to right. 142 143 <br><dt><code>--sysroot=</code><var>dir</var><dd><a name="index-sysroot-1006"></a>Use <var>dir</var> as the logical root directory for headers and libraries. 144For example, if the compiler would normally search for headers in 145<samp><span class="file">/usr/include</span></samp> and libraries in <samp><span class="file">/usr/lib</span></samp>, it will instead 146search <samp><var>dir</var><span class="file">/usr/include</span></samp> and <samp><var>dir</var><span class="file">/usr/lib</span></samp>. 147 148 <p>If you use both this option and the <samp><span class="option">-isysroot</span></samp> option, then 149the <samp><span class="option">--sysroot</span></samp> option will apply to libraries, but the 150<samp><span class="option">-isysroot</span></samp> option will apply to header files. 151 152 <p>The GNU linker (beginning with version 2.16) has the necessary support 153for this option. If your linker does not support this option, the 154header file aspect of <samp><span class="option">--sysroot</span></samp> will still work, but the 155library aspect will not. 156 157 <br><dt><code>-I-</code><dd><a name="index-I_002d-1007"></a>This option has been deprecated. Please use <samp><span class="option">-iquote</span></samp> instead for 158<samp><span class="option">-I</span></samp> directories before the <samp><span class="option">-I-</span></samp> and remove the <samp><span class="option">-I-</span></samp>. 159Any directories you specify with <samp><span class="option">-I</span></samp> options before the <samp><span class="option">-I-</span></samp> 160option are searched only for the case of ‘<samp><span class="samp">#include "</span><var>file</var><span class="samp">"</span></samp>’; 161they are not searched for ‘<samp><span class="samp">#include <</span><var>file</var><span class="samp">></span></samp>’. 162 163 <p>If additional directories are specified with <samp><span class="option">-I</span></samp> options after 164the <samp><span class="option">-I-</span></samp>, these directories are searched for all ‘<samp><span class="samp">#include</span></samp>’ 165directives. (Ordinarily <em>all</em> <samp><span class="option">-I</span></samp> directories are used 166this way.) 167 168 <p>In addition, the <samp><span class="option">-I-</span></samp> option inhibits the use of the current 169directory (where the current input file came from) as the first search 170directory for ‘<samp><span class="samp">#include "</span><var>file</var><span class="samp">"</span></samp>’. There is no way to 171override this effect of <samp><span class="option">-I-</span></samp>. With <samp><span class="option">-I.</span></samp> you can specify 172searching the directory which was current when the compiler was 173invoked. That is not exactly the same as what the preprocessor does 174by default, but it is often satisfactory. 175 176 <p><samp><span class="option">-I-</span></samp> does not inhibit the use of the standard system directories 177for header files. Thus, <samp><span class="option">-I-</span></samp> and <samp><span class="option">-nostdinc</span></samp> are 178independent. 179</dl> 180 181<!-- man end --> 182 </body></html> 183 184