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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>cuserid</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_002_080"> </a>NAME</h4><blockquote>cuserid - character login name of the user(<b>LEGACY</b>)</blockquote><h4><a name = "tag_000_002_081"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="stdio.h.html">stdio.h</a>>char *cuserid(char *<i>s</i>);</code></pre></blockquote><h4><a name = "tag_000_002_082"> </a>DESCRIPTION</h4><blockquote>The<i>cuserid()</i>function generates a character representation of thename associated with the real or effective user ID of the process.<p>If<i>s</i>is a null pointer, this representation is generated in an area that may bestatic (and thus overwritten by subsequent calls to<i>cuserid()</i>),the address of which is returned.If<i>s</i>is not a null pointer,<i>s</i>is assumed to point to an array of at least {L_cuserid} bytes; therepresentation is deposited in this array.The symbolic constant {L_cuserid} is defined in<i><a href="stdio.h.html"><stdio.h></a></i>and has a value greater than 0.<p>If the application uses any of the _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS interfaces, the<i>cuserid()</i>function must be called with a non-NULL parameter.</blockquote><h4><a name = "tag_000_002_083"> </a>RETURN VALUE</h4><blockquote>If<i>s</i>is not a null pointer,<i>s</i>is returned.If<i>s</i>is not a null pointer and the login name cannot be found,the null byte `\0' will be placed at<i>*s</i>.If<i>s</i>is a null pointer and the login name cannot be found,<i>cuserid()</i>returns a null pointer. If<i>s</i>is a null pointer and the login name can be found, the address of abuffer (possibly static) containing the login name is returned.</blockquote><h4><a name = "tag_000_002_084"> </a>ERRORS</h4><blockquote>No errors are defined.</blockquote><h4><a name = "tag_000_002_085"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_002_086"> </a>APPLICATION USAGE</h4><blockquote>The functionality of<i>cuserid()</i>defined in the POSIX.1-1988 standard (and Issue 3 of this specification)differs from that of historical implementations (and Issue 2 of thisspecification).In the ISO POSIX-1 standard,<i>cuserid()</i>is removed completely.In this specification, therefore, both functionalities are allowed.<p>The Issue 2 functionality can be obtained by using:<pre><code>getpwuid(getuid())</code></pre><p>The Issue 3 functionality can be obtained by using:<pre><code>getpwuid(geteuid())</code></pre></blockquote><h4><a name = "tag_000_002_087"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_002_088"> </a>SEE ALSO</h4><blockquote><i><a href="getlogin.html">getlogin()</a></i>,<i><a href="getpwnam.html">getpwnam()</a></i>,<i><a href="getpwuid.html">getpwuid()</a></i>,<i><a href="getuid.html">getuid()</a></i>,<i><a href="geteuid.html">geteuid()</a></i>,<i><a href="stdio.h.html"><stdio.h></a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from System V Release 2.0.</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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