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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
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diff --git a/share/doc/gcc/Environment-Variables.html b/share/doc/gcc/Environment-Variables.html new file mode 100644 index 0000000..b14c527 --- /dev/null +++ b/share/doc/gcc/Environment-Variables.html @@ -0,0 +1,356 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +Copyright (C) 1988-2023 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; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(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. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Using the GNU Compiler Collection (GCC): Environment Variables</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): Environment Variables"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Environment Variables"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Invoking-GCC.html#Invoking-GCC" rel="up" title="Invoking GCC"> +<link href="Precompiled-Headers.html#Precompiled-Headers" rel="next" title="Precompiled Headers"> +<link href="Spec-Files.html#Spec-Files" rel="previous" title="Spec Files"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Environment-Variables"></a> +<div class="header"> +<p> +Next: <a href="Precompiled-Headers.html#Precompiled-Headers" accesskey="n" rel="next">Precompiled Headers</a>, Previous: <a href="Spec-Files.html#Spec-Files" accesskey="p" rel="previous">Spec Files</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="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Environment-Variables-Affecting-GCC"></a> +<h3 class="section">3.21 Environment Variables Affecting GCC</h3> +<a name="index-environment-variables"></a> + +<p>This section describes several environment variables that affect how GCC +operates. Some of them work by specifying directories or prefixes to use +when searching for various kinds of files. Some are used to specify other +aspects of the compilation environment. +</p> +<p>Note that you can also specify places to search using options such as +<samp>-B</samp>, <samp>-I</samp> and <samp>-L</samp> (see <a href="Directory-Options.html#Directory-Options">Directory Options</a>). These +take precedence over places specified using environment variables, which +in turn take precedence over those specified by the configuration of GCC. +See <a href="http://gcc.gnu.org/onlinedocs/gccint/Driver.html#Driver">Controlling the Compilation Driver <samp>gcc</samp></a> in <cite>GNU Compiler Collection (GCC) Internals</cite>. +</p> +<dl compact="compact"> +<dd><a name="index-LANG"></a> +<a name="index-LC_005fCTYPE"></a> +<a name="index-LC_005fMESSAGES"></a> +<a name="index-LC_005fALL"></a> +<a name="index-locale"></a> +</dd> +<dt><code>LANG</code></dt> +<dt><code>LC_CTYPE</code></dt> +<dt><code>LC_MESSAGES</code></dt> +<dt><code>LC_ALL</code></dt> +<dd><p>These environment variables control the way that GCC uses +localization information which allows GCC to work with different +national conventions. GCC inspects the locale categories +<code>LC_CTYPE</code> and <code>LC_MESSAGES</code> if it has been configured to do +so. These locale categories can be set to any value supported by your +installation. A typical value is ‘<samp>en_GB.UTF-8</samp>’ for English in the United +Kingdom encoded in UTF-8. +</p> +<p>The <code>LC_CTYPE</code> environment variable specifies character +classification. GCC uses it to determine the character boundaries in +a string; this is needed for some multibyte encodings that contain quote +and escape characters that are otherwise interpreted as a string +end or escape. +</p> +<p>The <code>LC_MESSAGES</code> environment variable specifies the language to +use in diagnostic messages. +</p> +<p>If the <code>LC_ALL</code> environment variable is set, it overrides the value +of <code>LC_CTYPE</code> and <code>LC_MESSAGES</code>; otherwise, <code>LC_CTYPE</code> +and <code>LC_MESSAGES</code> default to the value of the <code>LANG</code> +environment variable. If none of these variables are set, GCC +defaults to traditional C English behavior. +</p> +<a name="index-TMPDIR"></a> +</dd> +<dt><code>TMPDIR</code></dt> +<dd><p>If <code>TMPDIR</code> is set, it specifies the directory to use for temporary +files. GCC uses temporary files to hold the output of one stage of +compilation which is to be used as input to the next stage: for example, +the output of the preprocessor, which is the input to the compiler +proper. +</p> +<a name="index-GCC_005fCOMPARE_005fDEBUG"></a> +</dd> +<dt><code>GCC_COMPARE_DEBUG</code></dt> +<dd><p>Setting <code>GCC_COMPARE_DEBUG</code> is nearly equivalent to passing +<samp>-fcompare-debug</samp> to the compiler driver. See the documentation +of this option for more details. +</p> +<a name="index-GCC_005fEXEC_005fPREFIX"></a> +</dd> +<dt><code>GCC_EXEC_PREFIX</code></dt> +<dd><p>If <code>GCC_EXEC_PREFIX</code> is set, it specifies a prefix to use in the +names of the subprograms executed by the compiler. No slash is added +when this prefix is combined with the name of a subprogram, but you can +specify a prefix that ends with a slash if you wish. +</p> +<p>If <code>GCC_EXEC_PREFIX</code> is not set, GCC attempts to figure out +an appropriate prefix to use based on the pathname it is invoked with. +</p> +<p>If GCC cannot find the subprogram using the specified prefix, it +tries looking in the usual places for the subprogram. +</p> +<p>The default value of <code>GCC_EXEC_PREFIX</code> is +<samp><var>prefix</var>/lib/gcc/</samp> where <var>prefix</var> is the prefix to +the installed compiler. In many cases <var>prefix</var> is the value +of <code>prefix</code> when you ran the <samp>configure</samp> script. +</p> +<p>Other prefixes specified with <samp>-B</samp> take precedence over this prefix. +</p> +<p>This prefix is also used for finding files such as <samp>crt0.o</samp> that are +used for linking. +</p> +<p>In addition, the prefix is used in an unusual way in finding the +directories to search for header files. For each of the standard +directories whose name normally begins with ‘<samp>/usr/local/lib/gcc</samp>’ +(more precisely, with the value of <code>GCC_INCLUDE_DIR</code>), GCC tries +replacing that beginning with the specified prefix to produce an +alternate directory name. Thus, with <samp>-Bfoo/</samp>, GCC searches +<samp>foo/bar</samp> just before it searches the standard directory +<samp>/usr/local/lib/bar</samp>. +If a standard directory begins with the configured +<var>prefix</var> then the value of <var>prefix</var> is replaced by +<code>GCC_EXEC_PREFIX</code> when looking for header files. +</p> +<a name="index-COMPILER_005fPATH"></a> +</dd> +<dt><code>COMPILER_PATH</code></dt> +<dd><p>The value of <code>COMPILER_PATH</code> is a colon-separated list of +directories, much like <code>PATH</code>. GCC tries the directories thus +specified when searching for subprograms, if it cannot find the +subprograms using <code>GCC_EXEC_PREFIX</code>. +</p> +<a name="index-LIBRARY_005fPATH"></a> +</dd> +<dt><code>LIBRARY_PATH</code></dt> +<dd><p>The value of <code>LIBRARY_PATH</code> is a colon-separated list of +directories, much like <code>PATH</code>. When configured as a native compiler, +GCC tries the directories thus specified when searching for special +linker files, if it cannot find them using <code>GCC_EXEC_PREFIX</code>. Linking +using GCC also uses these directories when searching for ordinary +libraries for the <samp>-l</samp> option (but directories specified with +<samp>-L</samp> come first). +</p> +<a name="index-LANG-1"></a> +<a name="index-locale-definition"></a> +</dd> +<dt><code>LANG</code></dt> +<dd><p>This variable is used to pass locale information to the compiler. One way in +which this information is used is to determine the character set to be used +when character literals, string literals and comments are parsed in C and C++. +When the compiler is configured to allow multibyte characters, +the following values for <code>LANG</code> are recognized: +</p> +<dl compact="compact"> +<dt>‘<samp>C-JIS</samp>’</dt> +<dd><p>Recognize JIS characters. +</p></dd> +<dt>‘<samp>C-SJIS</samp>’</dt> +<dd><p>Recognize SJIS characters. +</p></dd> +<dt>‘<samp>C-EUCJP</samp>’</dt> +<dd><p>Recognize EUCJP characters. +</p></dd> +</dl> + +<p>If <code>LANG</code> is not defined, or if it has some other value, then the +compiler uses <code>mblen</code> and <code>mbtowc</code> as defined by the default locale to +recognize and translate multibyte characters. +</p> +<a name="index-GCC_005fEXTRA_005fDIAGNOSTIC_005fOUTPUT"></a> +</dd> +<dt><code>GCC_EXTRA_DIAGNOSTIC_OUTPUT</code></dt> +<dd><p>If <code>GCC_EXTRA_DIAGNOSTIC_OUTPUT</code> is set to one of the following values, +then additional text will be emitted to stderr when fix-it hints are +emitted. <samp>-fdiagnostics-parseable-fixits</samp> and +<samp>-fno-diagnostics-parseable-fixits</samp> take precedence over this +environment variable. +</p> +<dl compact="compact"> +<dt>‘<samp>fixits-v1</samp>’</dt> +<dd><p>Emit parseable fix-it hints, equivalent to +<samp>-fdiagnostics-parseable-fixits</samp>. In particular, columns are +expressed as a count of bytes, starting at byte 1 for the initial column. +</p> +</dd> +<dt>‘<samp>fixits-v2</samp>’</dt> +<dd><p>As <code>fixits-v1</code>, but columns are expressed as display columns, +as per <samp>-fdiagnostics-column-unit=display</samp>. +</p></dd> +</dl> + +</dd> +</dl> + +<p>Some additional environment variables affect the behavior of the +preprocessor. +</p> + + + +<dl compact="compact"> +<dt><code>CPATH</code> +<a name="index-CPATH"></a> +</dt> +<dt><code>C_INCLUDE_PATH</code> +<a name="index-C_005fINCLUDE_005fPATH"></a> +</dt> +<dt><code>CPLUS_INCLUDE_PATH</code> +<a name="index-CPLUS_005fINCLUDE_005fPATH"></a> +</dt> +<dt><code>OBJC_INCLUDE_PATH</code> +<a name="index-OBJC_005fINCLUDE_005fPATH"></a> +</dt> +<dd><p>Each variable’s value is a list of directories separated by a special +character, much like <code>PATH</code>, 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> +<p><code>CPATH</code> specifies a list of directories to be searched as if +specified with <samp>-I</samp>, but after any paths given with <samp>-I</samp> +options on the command line. This environment variable is used +regardless of which language is being preprocessed. +</p> +<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>-isystem</samp>, but after any +paths given with <samp>-isystem</samp> options on the command line. +</p> +<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 +<code>CPATH</code> is <code>:/special/include</code>, that has the same +effect as ‘<samp><span class="nolinebreak">-I.</span> <span class="nolinebreak">-I/special/include</span><!-- /@w --></samp>’. +</p> + +<a name="index-dependencies-for-make-as-output"></a> +</dd> +<dt><code>DEPENDENCIES_OUTPUT</code> +<a name="index-DEPENDENCIES_005fOUTPUT"></a> +</dt> +<dd><p>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> +<p>The value of <code>DEPENDENCIES_OUTPUT</code> 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> +<p>In other words, this environment variable is equivalent to combining +the options <samp>-MM</samp> and <samp>-MF</samp> +(see <a href="Preprocessor-Options.html#Preprocessor-Options">Preprocessor Options</a>), +with an optional <samp>-MT</samp> switch too. +</p> +<a name="index-dependencies-for-make-as-output-1"></a> +</dd> +<dt><code>SUNPRO_DEPENDENCIES</code> +<a name="index-SUNPRO_005fDEPENDENCIES"></a> +</dt> +<dd><p>This variable is the same as <code>DEPENDENCIES_OUTPUT</code> (see above), +except that system header files are not ignored, so it implies +<samp>-M</samp> rather than <samp>-MM</samp>. However, the dependence on the +main input file is omitted. +See <a href="Preprocessor-Options.html#Preprocessor-Options">Preprocessor Options</a>. +</p> +</dd> +<dt><code>SOURCE_DATE_EPOCH</code> +<a name="index-SOURCE_005fDATE_005fEPOCH"></a> +</dt> +<dd><p>If this variable is set, its value specifies a UNIX timestamp to be +used in replacement of the current date and time in the <code>__DATE__</code> +and <code>__TIME__</code> macros, so that the embedded timestamps become +reproducible. +</p> +<p>The value of <code>SOURCE_DATE_EPOCH</code> must be a UNIX timestamp, +defined as the number of seconds (excluding leap seconds) since +01 Jan 1970 00:00:00 represented in ASCII; identical to the output of +<code>date +%s</code> on GNU/Linux and other systems that support the +<code>%s</code> extension in the <code>date</code> command. +</p> +<p>The value should be a known timestamp such as the last modification +time of the source or package and it should be set by the build +process. +</p> +</dd> +</dl> + + +<hr> +<div class="header"> +<p> +Next: <a href="Precompiled-Headers.html#Precompiled-Headers" accesskey="n" rel="next">Precompiled Headers</a>, Previous: <a href="Spec-Files.html#Spec-Files" accesskey="p" rel="previous">Spec Files</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="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |