244 lines
7.1 KiB
HTML
244 lines
7.1 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>getenv()--Get Value of Environment Variable</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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<!-- UNIX1 SCRIPT A converted by B2H R4.1 (346) (CMS) by V2DCIJB at -->
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<!-- RCHVMW2 on 1 Jun 1999 at 16:17:47 -->
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<!-- This file has undergone html cleanup on 04/29/02 by JET -->
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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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<!-- Java sync-link -->
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>getenv()--Get Value of Environment Variable</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax
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<pre>
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#include <stdlib.h>
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char *getenv(const char <em>*name</em>);
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</pre>
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Service Program Name: QP0ZCPA<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. See Usage Notes for more information.<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>getenv()</strong> function searches the job-level environment
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list for a string of the form <samp>name=value</samp>, where <samp>name</samp>
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is the environment variable and <samp>value</samp> is the value of the
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variable.</p>
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<p>The <em>name</em> parameter does not include the equal (=) symbol or the
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<samp>value</samp> of the environment variable <samp>name=value</samp>
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pair.</p>
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<br>
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<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
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<!-- Instead, use the commented out coding below to indicate NONE. -->
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<h3>Authorities and Locks</h3>
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<!-- Use this if there are no authorities and locks. -->
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>name</em></strong></dt>
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<dd>(Input) The name of an environment variable.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<table width="100%">
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<tr>
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<td align="left" valign="top" width="10%"><strong><em>value</em></strong></td>
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<td align="left" valign="top" width="90%"><strong>getenv()</strong>
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successfully found the environment string. The value returned is a pointer to
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the string containing the <samp>value</samp> for the specified <samp>
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name</samp> in the current environment.</td>
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</tr>
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<tr>
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<td align="left" valign="top" width="10%"><strong><em>NULL</em></strong></td>
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<td align="left" valign="top" width="90%"><strong>getenv()</strong> could not
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find the environment string. The <em>errno</em> variable is set to indicate the
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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>getenv()</strong> is not successful, <em>errno</em> indicates one
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of the following errors.</p>
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<dl compact>
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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>A referenced object is damaged. The object cannot be used.</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>[ENOENT]</em></dt>
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<dd>
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<p>No such path or directory.</p>
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<p>The directory or a component of the path name specified does not exist.</p>
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<p>A named file or directory does not exist or is an empty string.</p>
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<p>No entry found for name specified.</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>Usage Notes</h3>
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<ol>
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<li>Although <strong>getenv()</strong> is threadsafe, if a thread calls an
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environment variable function while another thread is accessing an environment
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variable from the environ array the thread may see undefined results. The
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environ array can be accessed directly or by using a pointer returned from the
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<strong>getenv()</strong> or <strong>Qp0zGetEnv()</strong> functions. The
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environment contents are only protected during calls to the environment
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variable functions.<br>
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<br>
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</li>
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<li>All environment variables are stored with an associated CCSID (coded
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character set identifier). Unless a different CCSID is specified, such as by
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using <strong>Qp0zPutEnv()</strong>, the default CCSID for the job is used as
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the CCSID associated with each environment variable string.<br>
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<br>
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</li>
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<li>No translation is done based on the CCSID. The CCSID is just stored and
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retrieved as an integer value associated with each environment variable.</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="evputenv.htm">putenv()</a>--Change or Add Environment
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Variable</li>
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<li><a href="evdltenv.htm">Qp0zDltEnv()</a>--Delete an Environment
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Variable</li>
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<li><a href="evdltsev.htm">Qp0zDltSysEnv()</a>--Delete a System-Level
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Environment Variable</li>
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<li><a href="evgetall.htm">Qp0zGetAllSysEnv()</a>--Get All System-Level
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Environment Variables</li>
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<li><a href="evgenvxt.htm">Qp0zGetEnv()</a>--Get Value of Environment Variable
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(Extended)</li>
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<li><a href="evgetsev.htm">Qp0zGetSysEnv()</a>--Get Value of System-Level
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Environment Variable</li>
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<li><a href="evinenv.htm">Qp0zInitEnv()</a>--Initialize Environment for
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Variables</li>
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<li><a href="evpenvxt.htm">Qp0zPutEnv()</a>--Change or Add Environment Variable
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(Extended)</li>
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<li><a href="evputsev.htm">Qp0zPutSysEnv()</a>--Change or Add a System-Level
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Environment</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>See the example of using <strong>getenv()</strong> in <a href=
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"evputenv.htm">putenv()</a>--Change or Add Environment Variable.</p>
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<p>For other examples, see the following:</p>
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<ul>
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<li><a href="../apiref/apiexusvar.htm">Using Environment Variables</a><br>
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</li>
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<li><a href="../apiref/apiexuspro.htm">Using the Spawn Process and Wait for Child
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Process APIs</a><br>
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</li>
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<li><a href="spawnu.htm#spawnuexmp">Using the Spawn Process (using NLS-enabled
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path name)</a></li>
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</ul>
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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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