255 lines
6.7 KiB
HTML
255 lines
6.7 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>res_search()--Search for Domain Name</title>
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<!-- Begin Header Records ========================================== -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Unix8 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!--End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>res_search()--Search for Domain Name</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <resolv.h>
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int res_search(char *<em>domain_name</em>,
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int <em>class</em>,
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int <em>type</em>,
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char *<em>answer_buffer</em>,
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int <em>answer_buffer_length</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV2<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <em>res_search()</em> function is used to make a query message and wait
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for a response.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>domain_name</strong></dt>
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<dd>(Input) The pointer to the domain name.<br>
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<br>
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</dd>
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<dt><strong>class</strong></dt>
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<dd>(Input) The class of data being looked for. See <a href=
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"resmkq.htm">res_mkquery()</a> or <arpa/nameser.h> for possible
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values.<br>
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<br>
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</dd>
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<dt><strong>type</strong></dt>
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<dd>(Input) The type of request being made. See <a href=
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"resmkq.htm">res_mkquery()</a> or <arpa/nameser.h> for possible
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values.<br>
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<br>
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</dd>
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<dt><strong>answer_buffer</strong></dt>
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<dd>(Output) The pointer to an address where the response is stored.<br>
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<br>
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</dd>
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<dt><strong>answer_buffer_length</strong></dt>
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<dd>(Input) The size of the answer area.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<p><em>res_search()</em> returns an integer. Possible values are:</p>
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<ul>
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<li>-1 (unsuccessful)<br>
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<br>
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</li>
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<li>n (successful), where n is the actual size of the answer returned.</li>
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</ul>
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<h3>Authorities:</h3>
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<p>Authorization of *R (allow access to the object) to the host aliases file
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specified by the <em>HOSTALIASES</em> environment variable.</p>
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<p>You also need *X authority to each directory in the path of the host aliases
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file.</p>
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<br>
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<h3>Error Conditions</h3>
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<p>When the <em>res_search()</em> function fails, <em>errno</em> can be set to
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one of the following:</p>
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<dl>
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<dt><em>[EACCES]</em></dt>
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<dd><p>Permission denied. The process does not have the
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appropriate privileges to the host aliases file specified by the
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<em>HOSTALIASES</em> environment variable.</p></dd>
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<dt><em>[EFAULT]</em></dt>
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<dd><p>The system detected a pointer that was invalid
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while attempting to access an input pointer.</p></dd>
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<dt><em>[EINVAL]</em></dt>
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<dd><p>The <strong>_res</strong> appears to be
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initialized but the reserved field is not set to zeros.</p></dd>
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<dd><p>When the <em>res_search()</em> function fails, <em>h_errno</em> (defined in
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<strong><netdb.h></strong>) can be set to one of the following:</p>
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<dl>
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<dt><em>[HOST_NOT_FOUND]</em></dt>
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<dd><p>(Set by the call to <em>res_query()</em> ) The
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domain name specified by the <em>domain_name</em> parameter was not found. The
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return code in the response packet was NXDOMAIN.</p></dd>
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<dt><em>[TRY_AGAIN]</em></dt>
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<dd><p>Either the name server is not running or the name
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server returned SERVFAIL in the response packet.</p></dd>
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<dt><em>[NO_RECOVERY]</em></dt>
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<dd><p>(Set by the call to <em>res_query()</em> ) An
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unrecoverable error has occurred. Either the domain name could not be
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compressed because it was invalid or the name server returned FORMERR, NOTIMP,
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or REFUSED.</p></dd>
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<dt><em>[NO_DATA]</em></dt>
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<dd><p>(Set by the call to <em>res_query()</em> ) The
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domain name exists but there is no data of the requested type.</p></dd>
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</dl></dd>
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</dl>
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<br>
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<h3>Usage Notes</h3>
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<ol>
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<li>The <em>res_search()</em> function implements the default and search rules
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controlled by the RES_DEFNAMES and RES_DNSRCH options. <em>res_search()</em>
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takes the domain name received in <em>domain_name</em>, and makes it fully
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qualified (if it is not already). <em>res_search()</em> also calls
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<em>res_query()</em>, passing it the different domain names to look up, until a
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successful response is received.<br>
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<br>
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</li>
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<li><em>res_search()</em> calls <em>res_init()</em> if the
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<strong>_res</strong> structure has not been initialized.<br>
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<br>
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</li>
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<li><em>res_search()</em> expects EBCDIC data as input. The output from
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<em>res_search()</em> is also EBCDIC.<br>
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<br>
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</li>
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<li>In a thread-enabled environment, the <strong>_res</strong> structure is
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shared among all threads within a process.<br>
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<br>
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</li>
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<li><em>res_search()</em> will resolve local host aliases to a domain name
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which are then resolved with a query using DNS. See <a href=
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"reshostalias.htm">res_hostalias()</a> for more information on aliases.<br>
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<br>
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</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li><a href="hstrerror.htm">hstrerror()</a>--Retrieve Resolver Error
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Message<br>
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<br>
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</li>
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<li><a href="resnsearch.htm">res_nsearch()</a>--Search for Domain Name<br>
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<br>
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</li>
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<li><a href="reshostalias.htm">res_hostalias()</a>--Retrieve the host alias<br>
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<br>
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</li>
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<li><a href="resini.htm">res_init()</a>--Initialize _res Structure<br>
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<br>
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</li>
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<li><a href="resmkq.htm">res_mkquery()</a>--Place Domain Query in Buffer<br>
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<br>
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</li>
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<li><a href="resqry.htm">res_query()</a>--Send Domain Query<br>
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<br>
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</li>
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<li><a href="resclo.htm">res_close()--</a>Close Socket and Reset _res
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Structure<br>
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<br>
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</li>
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<li><a href="ressnd.htm">res_send()</a>--Send Buffered Domain Query<br>
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<br>
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</li>
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<li><a href="resxlt.htm">res_xlate()</a>--Translate DNS Packets</li>
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</ul>
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<br>
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<hr>
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API introduced: V3R1
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a> </td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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