345 lines
9.5 KiB
HTML
345 lines
9.5 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>sysconf()--Get System Configuration Variables</title>
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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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<!-- Begin Header Records ========================================== -->
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<!-- file cleaned -->
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<!-- Unix2 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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<!-- Change History: -->
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<!-- 0206?? JET This file has undergone html cleanup -->
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<!-- 050407 JTROUS: fix enums, no change flag, V5R4 -->
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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 language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<h2>sysconf()--Get System Configuration Variables</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 <unistd.h>
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long sysconf(int <strong>name</strong>);
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</pre>
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<br>
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Service Program Name: QP0LLIB1<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>sysconf()</strong> function returns the value of a system
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configuration option. The configuration option to be obtained is specified by
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<strong>name</strong>.</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 named variable whose value is to be returned.</dd>
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</dl>
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<p>The value of <strong>name</strong> can be any one of the following symbols
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defined in the <<strong>unistd.h</strong>> header file, each
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corresponding to a system configuration option:</p>
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<table cellpadding="5">
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<!-- cols="25 75" -->
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<tr>
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<td align="left" valign="top"><em>_SC_ARG_MAX</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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ARG_MAX, which indicates the maximum number of bytes of arguments and
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environment data that can be passed in an <strong>exec</strong> function.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_CHILD_MAX</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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CHILD_MAX, which indicates the maximum number of jobs that a real user ID (UID)
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can have running simultaneously.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_CLK_TCK</em></td>
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<td align="left" valign="top">Represents the CLK_TCK macro, which indicates the
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number of clock ticks in a second. CLK_TCK is defined in the
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<<strong>time.h</strong>> header file.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_JOB_CONTROL</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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the _POSIX_JOB_CONTROL macro, which indicates that certain job control
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operations are implemented by this version of the operating system. If
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_POSIX_JOB_CONTROL is defined (in the <<strong>unistd.h</strong>> header
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file), various APIs, such as <strong>setpgid()</strong>, provide more function
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than when the macro is not defined.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_NGROUPS_MAX</em></td>
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<td align="left" valign="top">Represents NGROUPS_MAX, which indicates the
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maximum number of supplementary group IDs (GIDs) that can be associated with a
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job.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_OPEN_MAX</em></td>
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<td align="left" valign="top">Represents OPEN_MAX, which indicates the maximum
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number of files that a single job can have open at one time.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_PAGESIZE</em></td>
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<td align="left" valign="top">Represents the system hardware page size. The
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symbol _SC_PAGESIZE is defined as the decimal value 11.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_PAGE_SIZE</em></td>
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<td align="left" valign="top">Represents the system hardware page size. The
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symbol _SC_PAGE_SIZE is defined as the decimal value 12.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_SAVED_IDS</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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the _POSIX_SAVED_IDS macro, which indicates that this POSIX implementation has
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a saved set UID and a saved set GID. If the macro exists, it is defined in the
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<<strong>unistd.h</strong>> header file. This symbol affects the behavior
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of such functions as <strong>setuid()</strong> and <strong>
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setgid()</strong>.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_STREAM_MAX</em></td>
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<td align="left" valign="top">Represents the STREAM_MAX macro, which indicates
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the maximum number of streams that a job can have open at one time. The macro
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is defined in the <<strong>limits.h</strong>> header file.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_TZNAME_MAX</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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the TZNAME_MAX macro, which indicates the maximum length of the name of a time
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zone. If the macro exists, it is defined in the
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<<strong>limits.h</strong>> header file.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_VERSION</em></td>
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<td align="left" valign="top">(Not supported by the iSeries server). Represents
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the _POSIX_VERSION macro, which indicates the version of the POSIX.1 standard
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that the system conforms to. If the macro exists, it is defined in the
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<<strong>unistd.h</strong>> header file.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>_SC_CCSID</em></td>
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<td align="left" valign="top">Represents the default coded character set
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identifier (CCSID) used internally for integrated file system path names. A
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CCSID uniquely identifies the coded graphic character representation of a path
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name and includes such information as the character set and code page
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identifier. The symbol _SC_CCSID is defined as the decimal value 10.</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>Authorities</h3>
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<p>No authorization is required.</p>
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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="10 90" -->
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<tr>
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<td align="left" valign="top"><em>value</em></td>
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<td align="left" valign="top"><strong>sysconf()</strong> was successful. The
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value associated with the specified option is returned.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>-1</em></td>
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<td align="left" valign="top">One of the following has occurred:
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<ul>
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<li>The variable corresponding to <strong>name</strong> is valid but is not
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supported by the system. The <strong>errno</strong> global variable is not
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changed.</li>
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<li><strong>sysconf()</strong> failed in some other way. The <strong>
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errno</strong> is set to indicate the error.</li>
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</ul>
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</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>sysconf()</strong> is not successful, <strong>errno</strong>
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usually indicates one of the following errors. Under some conditions, <strong>
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errno</strong> could indicate an error other than those listed here.</p>
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<table cellpadding="5">
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<!-- cols="25 75" -->
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<tr>
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<th align="left" valign="bottom">Error condition</th>
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<th align="left" valign="bottom">Additional information</th>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBADFID">EBADFID</a>]</em></td>
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<td align="left" valign="top">
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</td></tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EINVAL">EINVAL</a>]</em></td>
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<td align="left" valign="top">
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</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 Messages</h3>
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<p>The following messages may be sent from this function:</p>
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<table width="100%" cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top">Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td align="left" valign="top">CPE3418 E</td>
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<td align="left" valign="top">Possible APAR condition or hardware failure.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF3CF2 E</td>
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<td align="left" valign="top">Error(s) occurred during running of &1
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API.</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>Related Information</h3>
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<ul>
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<li>The <<strong>unistd.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</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>The following example determines the value of OPEN_MAX:</p>
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<pre>
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#include <stdio.h>
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#include <unistd.h>
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#include <errno.h>
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main() {
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long result;
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errno = 0;
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puts("examining OPEN_MAX limit");
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if ((result = sysconf(_SC_OPEN_MAX)) == -1)
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if (errno == 0)
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puts("OPEN_MAX is not supported.");
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else perror("sysconf() error");
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else
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printf("OPEN_MAX is %ld\n", result);
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}
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</pre>
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<br>
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<p><strong>Output:</strong></p>
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<pre>
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examining OPEN_MAX limit
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OPEN_MAX is 200
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</pre>
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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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