246 lines
6.4 KiB
HTML
246 lines
6.4 KiB
HTML
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<!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>shmdt()-Detach Shared Memory Segment from Calling Process</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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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Direct1 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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<!-- This file has undergone html cleanup on 05/01/02 by JET -->
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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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<!--End Header Records -->
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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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<a name="Top_Of_Page"></a>
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<h2>shmdt()--Detach Shared Memory Segment from Calling Process</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/shm.h>
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int shmdt(const void *shmaddr);
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</pre>
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<br>
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Service Program Name: QP0ZUSHR<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 <strong>shmdt()</strong> function detaches the shared memory segment
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specified by <em>shmaddr</em> from the calling job. The <em>shmaddr</em>
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is the value returned by the <a href="ipcshmat.htm">shmat</a> function.<br>
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</p>
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<p>The system maintains status information about a shared memory segment which can
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be retrieved with the <a href="ipcshmct.htm">shmctl()</a> function. When a shared
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memory segment is successfully detached, the system sets the members of the
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<samp>shmid_ds</samp> structure as follows:<p>
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<ul>
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<li><samp>shm_nattch</samp> is decremented by 1.<p></li>
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<li><samp>shm_lpid</samp> is set to the process ID of the calling thread.<p></li>
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<li><samp>shm_dtime</samp> is set to the current time.</li>
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</ul>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>shmaddr</strong></dt>
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<dd>(Input) Address of the shared memory segment to be detached.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p><strong><a name="TBLAHDT1">Authorization Required for
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shmdt()</a></strong></p>
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<table border cellpadding="5">
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<!-- cols="60 20 20" -->
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<tr>
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<th align="left" valign="bottom">Object Referred to</th>
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<th align="left" valign="bottom">Authority Required</th>
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<th align="left" valign="bottom">errno</th>
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</tr>
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<tr>
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<td align="left" valign="top">Shared memory segment to be detached</td>
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<td align="left" valign="top">None</td>
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<td align="left" valign="top">None</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top"><strong>shmdt()</strong> was successful.</td>
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</tr>
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<tr>
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<td align="left" valign="top" nowrap><em>-1</em></td>
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<td align="left" valign="top"><strong>shmdt()</strong> was not successful. The
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<em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>shmdt()</strong> is not successful, <em>errno</em> usually
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indicates one of the following errors. Under some conditions, <em>errno</em>
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could indicate an error other than those listed here.</p>
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<dl>
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<dt><em>[EDAMAGE]</em></dt>
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<dd>
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<p>A damaged object was encountered.</p>
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<p>The shared memory segment has been damaged by a previous shared memory
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operation.</p>
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</dd>
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<dt><em>[EFAULT]</em></dt>
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<dd>
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<p>The address used for an argument is not correct.</p>
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<p>In attempting to use an argument in a call, the system detected an address
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that is not valid.</p>
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<p>While attempting to access a parameter passed to this function, the system
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detected an address that is not valid.</p>
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</dd>
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<dt><em>[EINVAL]</em></dt>
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<dd>
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<p>The value specified for the argument is not correct.</p>
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<p>A function was passed incorrect argument values, or an operation was
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attempted on an object and the operation specified is not supported for that
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type of object.</p>
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<p>An argument value is not valid, out of range, or NULL.</p>
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<p>The value of <em>shmaddr</em> is not the start address of a
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shared memory segment.</p>
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</dd>
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<dt><em>[ENOSYS]</em></dt>
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<dd>
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<p>Function not implemented.</p>
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<p>An attempt was made to use a function that is not available in this
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implementation for any object or any arguments.</p>
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<p>The function is not implemented.</p>
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</dd>
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<dt><em>[EUNKNOWN]</em></dt>
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<dd>
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<p>Unknown system state.</p>
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<p>The operation failed because of an unknown system state. See any messages in
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the job log and correct any errors that are indicated, then retry the
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operation.</p>
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</dd>
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</dl>
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<br>
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<h3>Error Messages</h3>
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<p>None.</p>
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<br>
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<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
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<ol>
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<li>This function does not delete the shared memory segment. To delete a shared
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memory segment, use the <strong>shmctl()</strong> function with the <em>cmd</em>
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parameter set to IPC_RMID.</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>The <<strong>sys/shm.h</strong>> file (see <a href="unix13.htm">
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Header Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="ipcshmat.htm">shmat()</a>--Attach Shared Memory Segment to Current
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Process<br>
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<br>
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</li>
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<li><a href="ipcshmct.htm">shmctl()</a>--Perform Shared Memory Control
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Operations<br>
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<br>
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</li>
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<li><a href="ipcshmgt.htm">shmget()</a>--Get ID of Shared Memory Segment with
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Key</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<p>For an example of using this function, see <a href="../apiref/apiexusmem.htm">
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Using Semaphores and Shared Memory</a> in Examples: APIs.</p>
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<br>
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<hr>
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API introduced: V3R6
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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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