113 lines
6.1 KiB
HTML
113 lines
6.1 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="AF_UNIX address family" />
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<meta name="abstract" content="This address family provides interprocess communications on the same system that uses the socket APIs. The address is really a path name to an entry in the file system." />
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<meta name="description" content="This address family provides interprocess communications on the same system that uses the socket APIs. The address is really a path name to an entry in the file system." />
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<meta name="DC.Relation" scheme="URI" content="address.htm" />
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<meta name="DC.Relation" scheme="URI" content="uafunix.htm" />
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<meta name="DC.Relation" scheme="URI" content="../apis/unlink.htm" />
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<meta name="DC.Relation" scheme="URI" content="cafunixccsid.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Identifier" content="cafunix" />
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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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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>AF_UNIX address family</title>
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</head>
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<body id="cafunix"><a name="cafunix"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">AF_UNIX address family</h1>
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<div><p>This address family provides interprocess communications on the
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same system that uses the socket APIs. The address is really a path name to
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an entry in the file system.</p>
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<div class="section"><p>You can create sockets in the root directory or any open file
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system but file systems such as QSYS or QDOC. The program must bind an AF_UNIX,
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SOCK_DGRAM socket to a name to receive any datagrams back. In addition, the
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program must explicitly remove the file system object with the <span class="apiname">unlink()</span> API
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when the socket is closed. </p>
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</div>
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<div class="section"><p>Sockets with the address family AF_UNIX use the sockaddr_un
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address structure. This address structure changes if you use _XOPEN_SOURCE
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macro to implement BSD 4.4/ UNIX<sup>®</sup> 98 specifications. For the sockaddr_un
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address structure, these differences are summarized in the table:</p>
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</div>
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<div class="section"><div class="p">
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. Differences between BSD 4.3 and BSD 4.4/ UNIX 98 for sockaddr_un
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address structure</caption><thead align="left"><tr><th valign="top" id="d0e44">BSD 4.3 sockaddr_un address structure</th>
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<th valign="top" id="d0e46">BSD 4.4/ UNIX 98 sockaddr_un address structure</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e44 "> <pre>struct sockaddr_un {
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short sun_family;
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char sun_path[126];
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}; </pre>
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</td>
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<td valign="top" headers="d0e46 "> <pre>struct sockaddr_un {
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uint8_t sun_len;
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sa_family_t sun_family;
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char sun_path[126];
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};</pre>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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</div>
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<div class="section"><div class="p">
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 2. AF_UNIX address structure </caption><thead align="left"><tr><th valign="top" id="d0e72">Address structure field</th>
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<th valign="top" id="d0e74">Definition</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e72 ">sun_len</td>
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<td valign="top" headers="d0e74 ">This field contains the length of the address for UNIX 98
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specifications. <div class="note"><span class="notetitle">Note:</span> The: sun_len field is only provided for BSD 4.4 compatibility.
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It is not necessary to use this field even when using BSD 4.4/ UNIX 98 compatibility.
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The field is ignored on input addresses.</div>
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</td>
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</tr>
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<tr><td valign="top" headers="d0e72 ">sun_family</td>
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<td valign="top" headers="d0e74 ">This field contains the address family.</td>
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</tr>
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<tr><td valign="top" headers="d0e72 ">sun_path</td>
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<td valign="top" headers="d0e74 ">This field contains the path name to an entry in the
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file system.</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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</div>
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<div class="section"><p>For AF_UNIX address family, protocol specifications do not apply
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because protocol standards are not involved. The communications mechanism
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the two processes use is specific to the machine.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="address.htm" title="The address family parameter on a socket() determines the format of the address structure to use on socket functions.">Socket address family</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="uafunix.htm" title="The AF_UNIX address family (sockets using the AF_UNIX or AF_UNIX_CCSID address families) can be connection-oriented (type SOCK_STREAM) or they can be connectionless (type SOCK_DGRAM).">Use AF_UNIX address family</a></div>
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<div><a href="cafunixccsid.htm" title="The AF_UNIX_CCSID family is compatible with the AF_UNIX address family and has the same limitations.">AF_UNIX_CCSID address family</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../apis/unlink.htm">unlink()</a></div>
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</div>
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</div>
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</body>
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</html>
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