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<a name="getenv"></a>
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<div class="header">
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<p>
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Next: <a href="itoa.html#itoa" accesskey="n" rel="next">itoa</a>, Previous: <a href="exit.html#exit" accesskey="p" rel="prev">exit</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="getenv_002d_002d_002dlook-up-environment-variable"></a>
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<h3 class="section">2.18 <code>getenv</code>—look up environment variable</h3>
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<a name="index-getenv"></a>
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<a name="index-environ"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <stdlib.h>
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char *getenv(const char *<var>name</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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<code>getenv</code> searches the list of environment variable names and values
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(using the global pointer “<code>char **environ</code>”) for a variable whose
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name matches the string at <var>name</var>. If a variable name matches,
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<code>getenv</code> returns a pointer to the associated value.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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A pointer to the (string) value of the environment variable, or
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<code>NULL</code> if there is no such environment variable.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>getenv</code> is ANSI, but the rules for properly forming names of environment
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variables vary from one system to another.
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</p>
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<p><code>getenv</code> requires a global pointer <code>environ</code>.
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