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<h2 class="chapter">3 GCC Command Options</h2>
<p><a name="index-GCC-command-options-67"></a><a name="index-command-options-68"></a><a name="index-options_002c-GCC-command-69"></a>
<!-- man begin DESCRIPTION -->
When you invoke GCC, it normally does preprocessing, compilation,
assembly and linking. The “overall options” allow you to stop this
process at an intermediate stage. For example, the <samp><span class="option">-c</span></samp> option
says not to run the linker. Then the output consists of object files
output by the assembler.
<p>Other options are passed on to one stage of processing. Some options
control the preprocessor and others the compiler itself. Yet other
options control the assembler and linker; most of these are not
documented here, since you rarely need to use any of them.
<p><a name="index-C-compilation-options-70"></a>Most of the command-line options that you can use with GCC are useful
for C programs; when an option is only useful with another language
(usually C++), the explanation says so explicitly. If the description
for a particular option does not mention a source language, you can use
that option with all supported languages.
<p><a name="index-C_002b_002b-compilation-options-71"></a>See <a href="Invoking-G_002b_002b.html#Invoking-G_002b_002b">Compiling C++ Programs</a>, for a summary of special
options for compiling C++ programs.
<p><a name="index-grouping-options-72"></a><a name="index-options_002c-grouping-73"></a>The <samp><span class="command">gcc</span></samp> program accepts options and file names as operands. Many
options have multi-letter names; therefore multiple single-letter options
may <em>not</em> be grouped: <samp><span class="option">-dv</span></samp> is very different from ‘<samp><span class="samp">-d -v</span></samp>’<!-- /@w -->.
<p><a name="index-order-of-options-74"></a><a name="index-options_002c-order-75"></a>You can mix options and other arguments. For the most part, the order
you use doesn't matter. Order does matter when you use several
options of the same kind; for example, if you specify <samp><span class="option">-L</span></samp> more
than once, the directories are searched in the order specified. Also,
the placement of the <samp><span class="option">-l</span></samp> option is significant.
<p>Many options have long names starting with ‘<samp><span class="samp">-f</span></samp>’ or with
‘<samp><span class="samp">-W</span></samp>’—for example,
<samp><span class="option">-fmove-loop-invariants</span></samp>, <samp><span class="option">-Wformat</span></samp> and so on. Most of
these have both positive and negative forms; the negative form of
<samp><span class="option">-ffoo</span></samp> is <samp><span class="option">-fno-foo</span></samp>. This manual documents
only one of these two forms, whichever one is not the default.
<!-- man end -->
<p>See <a href="Option-Index.html#Option-Index">Option Index</a>, for an index to GCC's options.
<ul class="menu">
<li><a accesskey="1" href="Option-Summary.html#Option-Summary">Option Summary</a>: Brief list of all options, without explanations.
<li><a accesskey="2" href="Overall-Options.html#Overall-Options">Overall Options</a>: Controlling the kind of output:
an executable, object files, assembler files,
or preprocessed source.
<li><a accesskey="3" href="Invoking-G_002b_002b.html#Invoking-G_002b_002b">Invoking G++</a>: Compiling C++ programs.
<li><a accesskey="4" href="C-Dialect-Options.html#C-Dialect-Options">C Dialect Options</a>: Controlling the variant of C language compiled.
<li><a accesskey="5" href="C_002b_002b-Dialect-Options.html#C_002b_002b-Dialect-Options">C++ Dialect Options</a>: Variations on C++.
<li><a accesskey="6" href="Objective_002dC-and-Objective_002dC_002b_002b-Dialect-Options.html#Objective_002dC-and-Objective_002dC_002b_002b-Dialect-Options">Objective-C and Objective-C++ Dialect Options</a>: Variations on Objective-C
and Objective-C++.
<li><a accesskey="7" href="Language-Independent-Options.html#Language-Independent-Options">Language Independent Options</a>: Controlling how diagnostics should be
formatted.
<li><a accesskey="8" href="Warning-Options.html#Warning-Options">Warning Options</a>: How picky should the compiler be?
<li><a accesskey="9" href="Debugging-Options.html#Debugging-Options">Debugging Options</a>: Symbol tables, measurements, and debugging dumps.
<li><a href="Optimize-Options.html#Optimize-Options">Optimize Options</a>: How much optimization?
<li><a href="Preprocessor-Options.html#Preprocessor-Options">Preprocessor Options</a>: Controlling header files and macro definitions.
Also, getting dependency information for Make.
<li><a href="Assembler-Options.html#Assembler-Options">Assembler Options</a>: Passing options to the assembler.
<li><a href="Link-Options.html#Link-Options">Link Options</a>: Specifying libraries and so on.
<li><a href="Directory-Options.html#Directory-Options">Directory Options</a>: Where to find header files and libraries.
Where to find the compiler executable files.
<li><a href="Spec-Files.html#Spec-Files">Spec Files</a>: How to pass switches to sub-processes.
<li><a href="Target-Options.html#Target-Options">Target Options</a>: Running a cross-compiler, or an old version of GCC.
<li><a href="Submodel-Options.html#Submodel-Options">Submodel Options</a>: Specifying minor hardware or convention variations,
such as 68010 vs 68020.
<li><a href="Code-Gen-Options.html#Code-Gen-Options">Code Gen Options</a>: Specifying conventions for function calls, data layout
and register usage.
<li><a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>: Env vars that affect GCC.
<li><a href="Precompiled-Headers.html#Precompiled-Headers">Precompiled Headers</a>: Compiling a header once, and using it many times.
</ul>
<!-- man begin OPTIONS -->
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