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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>getenv</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_005_524"> </a>NAME</h4><blockquote>getenv - get value of an environment variable</blockquote><h4><a name = "tag_000_005_525"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="stdlib.h.html">stdlib.h</a>>char *getenv(const char *<i>name</i>);</code></pre></blockquote><h4><a name = "tag_000_005_526"> </a>DESCRIPTION</h4><blockquote>The<i>getenv()</i>function searches the environment list for a string of the form"<i>name=value</i>",and returns a pointer to a string containing the<i>value</i>for the specified name.If the specified name cannot be found, a null pointer is returned.The string pointed to must not be modified by the application, butmay be overwritten by a subsequent call to<i>getenv()</i>or<i><a href="putenv.html">putenv()</a></i>but will not be overwritten by a call to any other function in this document.<p>This interface need not be reentrant.</blockquote><h4><a name = "tag_000_005_527"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>getenv()</i>returns a pointer to a string containing the<i>value</i>for the specified<i>name</i>.If the specified name cannot be found a null pointer is returned.<p>The return value from<i>getenv()</i>may point to static data which may be overwritten by subsequent calls to<i>getenv()</i>or<i><a href="putenv.html">putenv()</a></i>.</blockquote><h4><a name = "tag_000_005_528"> </a>ERRORS</h4><blockquote>No errors are defined.</blockquote><h4><a name = "tag_000_005_529"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_530"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_531"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_532"> </a>SEE ALSO</h4><blockquote><i><a href="exec.html">exec</a></i>,<i><a href="putenv.html">putenv()</a></i>,<i><a href="stdlib.h.html"><stdlib.h></a></i>,the <b>XBD</b> specification, <a href="../xbd/envvar.html"><b>Environment Variables</b> </a>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from Issue 1 of the SVID.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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