You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
135 lines
7.2 KiB
HTML
135 lines
7.2 KiB
HTML
4 years ago
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Environment Variables - The C Preprocessor</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="The C Preprocessor">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="prev" href="Invocation.html#Invocation" title="Invocation">
|
||
|
|
<link rel="next" href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License" title="GNU Free Documentation License">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
Copyright (C) 1987-2015 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
||
|
|
any later version published by the Free Software Foundation. A copy of
|
||
|
|
the license is included in the
|
||
|
|
section entitled ``GNU Free Documentation License''.
|
||
|
|
|
||
|
|
This manual contains no Invariant Sections. The Front-Cover Texts are
|
||
|
|
(a) (see below), and the Back-Cover Texts are (b) (see below).
|
||
|
|
|
||
|
|
(a) The FSF's Front-Cover Text is:
|
||
|
|
|
||
|
|
A GNU Manual
|
||
|
|
|
||
|
|
(b) The FSF's Back-Cover Text is:
|
||
|
|
|
||
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
||
|
|
software. Copies published by the Free Software Foundation raise
|
||
|
|
funds for GNU development.
|
||
|
|
-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="Environment-Variables"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License">GNU Free Documentation License</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Invocation.html#Invocation">Invocation</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h2 class="chapter">13 Environment Variables</h2>
|
||
|
|
|
||
|
|
<p><a name="index-environment-variables-203"></a><!-- man begin ENVIRONMENT -->
|
||
|
|
|
||
|
|
<p>This section describes the environment variables that affect how CPP
|
||
|
|
operates. You can use them to specify directories or prefixes to use
|
||
|
|
when searching for include files, or to control dependency output.
|
||
|
|
|
||
|
|
<p>Note that you can also specify places to search using options such as
|
||
|
|
<samp><span class="option">-I</span></samp>, and control dependency output with options like
|
||
|
|
<samp><span class="option">-M</span></samp> (see <a href="Invocation.html#Invocation">Invocation</a>). These take precedence over
|
||
|
|
environment variables, which in turn take precedence over the
|
||
|
|
configuration of GCC.
|
||
|
|
|
||
|
|
<!-- Copyright (C) 1999-2015 Free Software Foundation, Inc. -->
|
||
|
|
<!-- This is part of the CPP and GCC manuals. -->
|
||
|
|
<!-- For copying conditions, see the file gcc.texi. -->
|
||
|
|
<!-- -->
|
||
|
|
<!-- Environment variables affecting the preprocessor -->
|
||
|
|
<!-- -->
|
||
|
|
<!-- If this file is included with the flag ``cppmanual'' set, it is -->
|
||
|
|
<!-- formatted for inclusion in the CPP manual; otherwise the main GCC manual. -->
|
||
|
|
<dl>
|
||
|
|
<dt><samp><span class="env">CPATH</span></samp><a name="index-CPATH-204"></a><dt><samp><span class="env">C_INCLUDE_PATH</span></samp><a name="index-C_005fINCLUDE_005fPATH-205"></a><dt><samp><span class="env">CPLUS_INCLUDE_PATH</span></samp><a name="index-CPLUS_005fINCLUDE_005fPATH-206"></a><dt><samp><span class="env">OBJC_INCLUDE_PATH</span></samp><a name="index-OBJC_005fINCLUDE_005fPATH-207"></a><dd><!-- Commented out until ObjC++ is part of GCC: -->
|
||
|
|
<!-- @itemx OBJCPLUS_INCLUDE_PATH -->
|
||
|
|
Each variable's value is a list of directories separated by a special
|
||
|
|
character, much like <samp><span class="env">PATH</span></samp>, in which to look for header files.
|
||
|
|
The special character, <code>PATH_SEPARATOR</code>, is target-dependent and
|
||
|
|
determined at GCC build time. For Microsoft Windows-based targets it is a
|
||
|
|
semicolon, and for almost all other targets it is a colon.
|
||
|
|
|
||
|
|
<p><samp><span class="env">CPATH</span></samp> specifies a list of directories to be searched as if
|
||
|
|
specified with <samp><span class="option">-I</span></samp>, but after any paths given with <samp><span class="option">-I</span></samp>
|
||
|
|
options on the command line. This environment variable is used
|
||
|
|
regardless of which language is being preprocessed.
|
||
|
|
|
||
|
|
<p>The remaining environment variables apply only when preprocessing the
|
||
|
|
particular language indicated. Each specifies a list of directories
|
||
|
|
to be searched as if specified with <samp><span class="option">-isystem</span></samp>, but after any
|
||
|
|
paths given with <samp><span class="option">-isystem</span></samp> options on the command line.
|
||
|
|
|
||
|
|
<p>In all these variables, an empty element instructs the compiler to
|
||
|
|
search its current working directory. Empty elements can appear at the
|
||
|
|
beginning or end of a path. For instance, if the value of
|
||
|
|
<samp><span class="env">CPATH</span></samp> is <code>:/special/include</code>, that has the same
|
||
|
|
effect as ‘<samp><span class="samp">-I. -I/special/include<!-- /@w --></span></samp>’.
|
||
|
|
|
||
|
|
<!-- man end -->
|
||
|
|
<p>See also <a href="Search-Path.html#Search-Path">Search Path</a>.
|
||
|
|
<!-- man begin ENVIRONMENT -->
|
||
|
|
|
||
|
|
<br><dt><samp><span class="env">DEPENDENCIES_OUTPUT</span></samp><a name="index-DEPENDENCIES_005fOUTPUT-208"></a><dd><a name="index-dependencies-for-make-as-output-209"></a>If this variable is set, its value specifies how to output
|
||
|
|
dependencies for Make based on the non-system header files processed
|
||
|
|
by the compiler. System header files are ignored in the dependency
|
||
|
|
output.
|
||
|
|
|
||
|
|
<p>The value of <samp><span class="env">DEPENDENCIES_OUTPUT</span></samp> can be just a file name, in
|
||
|
|
which case the Make rules are written to that file, guessing the target
|
||
|
|
name from the source file name. Or the value can have the form
|
||
|
|
‘<samp><var>file</var> <var>target</var></samp>’, in which case the rules are written to
|
||
|
|
file <var>file</var> using <var>target</var> as the target name.
|
||
|
|
|
||
|
|
<p>In other words, this environment variable is equivalent to combining
|
||
|
|
the options <samp><span class="option">-MM</span></samp> and <samp><span class="option">-MF</span></samp>
|
||
|
|
(see <a href="Invocation.html#Invocation">Invocation</a>),
|
||
|
|
with an optional <samp><span class="option">-MT</span></samp> switch too.
|
||
|
|
|
||
|
|
<br><dt><samp><span class="env">SUNPRO_DEPENDENCIES</span></samp><a name="index-SUNPRO_005fDEPENDENCIES-210"></a><dd><a name="index-dependencies-for-make-as-output-211"></a>This variable is the same as <samp><span class="env">DEPENDENCIES_OUTPUT</span></samp> (see above),
|
||
|
|
except that system header files are not ignored, so it implies
|
||
|
|
<samp><span class="option">-M</span></samp> rather than <samp><span class="option">-MM</span></samp>. However, the dependence on the
|
||
|
|
main input file is omitted.
|
||
|
|
See <a href="Invocation.html#Invocation">Invocation</a>.
|
||
|
|
</dl>
|
||
|
|
<!-- man end -->
|
||
|
|
|
||
|
|
<!-- Special handling for inclusion in the install manual. -->
|
||
|
|
<!-- man begin DESCRIPTION -->
|
||
|
|
</body></html>
|
||
|
|
|