693 lines
15 KiB
HTML
693 lines
15 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>close()--Close File or Socket Descriptor</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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<!-- 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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<!-- 010320 JTROUS Include Journal ERRNOs, should have in V5R1 -->
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<!-- 011022 JTROUS Changes from API Review 1, V5R2 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- 020313 JTROUS Changes for scan processing, V5R3, DCR 98680 -->
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<!-- 020618 EMIG Updates for NFS threadsafety, V5R3 -->
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<!-- This file has undergone html cleanup June 2002 by JET -->
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<!-- 020718 MFENLON: updated for QFileSvr.400 threadsafety, V5R3 -->
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<!-- 030701 JTROUS Add EDEADLK errno (due to scan mutex), v5r3a -->
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<!-- 050322 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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<!--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>close()--Close File or Socket Descriptor</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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int close(int <em>fildes</em>);
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</pre>
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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: Conditional; see <a href="#USAGE_NOTES">Usage
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Notes</a>.<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>close()</strong> function closes a descriptor, <em>fildes</em>.
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This frees the descriptor to be returned by future <strong>open()</strong>
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calls and other calls that create descriptors.</p>
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<p>When the last open descriptor for a file is closed, the file itself is
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closed. If the link count of the file is zero at that time, the space occupied
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by the file is freed and the file becomes inaccessible.</p>
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<p><strong>close()</strong> unlocks (removes) all outstanding byte locks that a
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job has on the associated file.</p>
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<p>When all file descriptors associated with a pipe or FIFO special file are
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closed, any data remaining in the pipe or FIFO is discarded and internal
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storage used is returned to the system.</p>
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<p>When <em>fildes</em> refers to a socket, <strong>close()</strong> closes the
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socket identified by the descriptor.</p>
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<p>For information about the
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exit point that can be associated with <strong>close()</strong>, see <a href=
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"ifscloseexit.htm">Integrated File System Scan on Close Exit Programs</a>. </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>fildes</em></strong></dt>
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<dd>(Input) The descriptor to be closed.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>No authorization is required. Authorization is verified during <strong>
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open()</strong>, <strong>creat()</strong>, or <strong>socket()</strong>.</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="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>close()</strong> was successful.</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"><strong>close()</strong> was not successful. The
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<em>errno</em> global 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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<h3>Error Conditions</h3>
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<p>If <strong>close()</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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<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#EACCES">EACCES</a>]</em></td>
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<td align="left" valign="top">
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<p>If you are accessing a remote file through the Network File System, update
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operations to file permissions at the server are not reflected at the client
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until updates to data that is stored locally by the Network File System take
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place. (Several options on the Add Mounted File System (ADDMFS) command
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determine the time between refresh operations of local data.) Access to a
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remote file may also fail due to different mappings of user IDs (UID) or group
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IDs (GID) on the local and remote systems.</p>
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</td>
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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#EAGAIN">EAGAIN</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBADF">EBADF</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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<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>
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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#EBUSY">EBUSY</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EDAMAGE">EDAMAGE</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EDEADLK">EDEADLK</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EINTR">EINTR</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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<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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EIO">EIO</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNDAMAGE">EJRNDAMAGE</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNENTTOOLONG">EJRNENTTOOLONG</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNINACTIVE">EJRNINACTIVE</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNRCVSPC">EJRNRCVSPC</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENEWJRN">ENEWJRN</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENEWJRNRCV">ENEWJRNRCV</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOBUFS">ENOBUFS</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOSPC">ENOSPC</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOSYS">ENOSYS</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOTAVAIL">ENOTAVAIL</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOTSAFE">ENOTSAFE</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ESCANFAILURE">ESCANFAILURE</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ESTALE">ESTALE</a>]</em></td>
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<td align="left" valign="top">
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<p>If you are accessing a remote file through the Network File System, the file
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may have been deleted at the server.</p>
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</td>
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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#EUNKNOWN">EUNKNOWN</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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<p>Additionally, if interaction with a file server is required to access the
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object, <em>errno</em> could indicate one of the following errors:</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#EADDRNOTAVAIL">EADDRNOTAVAIL</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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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ECONNABORTED">ECONNABORTED</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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|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ECONNREFUSED">ECONNREFUSED</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ECONNRESET">ECONNRESET</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EHOSTDOWN">EHOSTDOWN</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EHOSTUNREACH">EHOSTUNREACH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETDOWN">ENETDOWN</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETRESET">ENETRESET</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETUNREACH">ENETUNREACH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ETIMEDOUT">ETIMEDOUT</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EUNATCH">EUNATCH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Error Messages</h3>
|
||
|
|
|
||
|
|
<p>The following messages may be sent from this function:</p>
|
||
|
|
|
||
|
|
<table width="100%" cellpadding="5">
|
||
|
|
<!-- cols="15 85" -->
|
||
|
|
<tr>
|
||
|
|
<th align="left" valign="top" nowrap>Message ID</th>
|
||
|
|
<th align="left" valign="top">Error Message Text</th>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">CPE3418 E</td>
|
||
|
|
<td align="left" valign="top">Possible APAR condition or hardware failure.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">CPF3CF2 E</td>
|
||
|
|
<td align="left" valign="top">Error(s) occurred during running of &1
|
||
|
|
API.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">CPF9872 E</td>
|
||
|
|
<td align="left" valign="top">Program or service program &1 in library
|
||
|
|
&2 ended. Reason code &3.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">CPFA081 E</td>
|
||
|
|
<td align="left" valign="top">Unable to set return value or error code.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">CPFA0D4 E</td>
|
||
|
|
<td align="left" valign="top">File system error occurred. Error number
|
||
|
|
&1.</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
|
||
|
|
|
||
|
|
<ol>
|
||
|
|
<li>This function will fail with
|
||
|
|
error code [EBADF] when <em>fildes</em> is a scan descriptor that was passed to
|
||
|
|
one of the scan-related exit programs. See <a href="ifsopenexit.htm">Integrated
|
||
|
|
File System Scan on Open Exit Programs</a> and <a href="ifscloseexit.htm">
|
||
|
|
Integrated File System Scan on Close Exit Programs</a> for more information.
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>This function will fail with error code [ENOTSAFE] when all the following
|
||
|
|
conditions are true:<br>
|
||
|
|
<br>
|
||
|
|
<ul>
|
||
|
|
<li>Where multiple threads exist in the job.
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The object on which this function is operating resides in a file system
|
||
|
|
that is not threadsafe. Only the following file systems are threadsafe for this
|
||
|
|
function:<br>
|
||
|
|
<br>
|
||
|
|
<ul>
|
||
|
|
<li>"Root" (/)</li>
|
||
|
|
|
||
|
|
<li>QOpenSys</li>
|
||
|
|
|
||
|
|
<li>User-defined</li>
|
||
|
|
|
||
|
|
<li>QNTC</li>
|
||
|
|
|
||
|
|
<li>QSYS.LIB</li>
|
||
|
|
|
||
|
|
<li>Independent ASP QSYS.LIB</li>
|
||
|
|
|
||
|
|
<li>QOPT</li>
|
||
|
|
|
||
|
|
<li>Network File System</li>
|
||
|
|
|
||
|
|
|
||
|
|
<li>QFileSvr.400</li>
|
||
|
|
|
||
|
|
</ul>
|
||
|
|
</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>When a socket descriptor is closed, the system tries to send any queued
|
||
|
|
data associated with the socket.<br>
|
||
|
|
<br>
|
||
|
|
<ul>
|
||
|
|
<li>For <samp>AF_INET</samp> sockets, depending on
|
||
|
|
whether the <samp>SO_LINGER</samp> socket option is set, queued data may be
|
||
|
|
discarded.
|
||
|
|
|
||
|
|
<p><strong>Note:</strong> For these sockets, the default value for the <samp>
|
||
|
|
SO_LINGER</samp> socket option has the option flag set off (the system attempts
|
||
|
|
to send any queued data with an infinite wait time).</p>
|
||
|
|
</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>A socket descriptor being shared among multiple processes is not closed
|
||
|
|
until the process that issued the <em>close()</em> is the last process with
|
||
|
|
access to the socket.</li>
|
||
|
|
</ol>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Related Information</h3>
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li>The <<strong>unistd.h</strong>> file (see <a href="unix13.htm">Header
|
||
|
|
Files for UNIX-Type Functions</a>)
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="creat.htm">creat()</a>--Create or Rewrite File
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="dup.htm">dup()</a>--Duplicate Open File Descriptor
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="dup2.htm">dup2()</a>--Duplicate Open File Descriptor to Another
|
||
|
|
Descriptor
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="fcntl.htm">fcntl()</a>--Perform File Control Command
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href=
|
||
|
|
"ifscloseexit.htm">Integrated File System Scan on Close Exit Programs</a>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="open.htm">open()</a>--Open File
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="ssocko.htm">setsockopt()</a>--Set Socket Options
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="unlink.htm">unlink()</a>--Remove Link to File</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Example</h3>
|
||
|
|
|
||
|
|
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
|
||
|
|
for information pertaining to code examples.</p>
|
||
|
|
|
||
|
|
<p>The following example uses <strong>close()</strong></p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
main() {
|
||
|
|
int fd1, fd2;
|
||
|
|
char out[20]="Test string",
|
||
|
|
fn[]="test.file",
|
||
|
|
in[20];
|
||
|
|
short write_error;
|
||
|
|
|
||
|
|
memset(in, 0x00, sizeof(in));
|
||
|
|
|
||
|
|
write_error = 0;
|
||
|
|
|
||
|
|
if ( (fd1 = creat(fn,S_IRWXU)) == -1)
|
||
|
|
perror("creat() error");
|
||
|
|
else if ( (fd2 = open(fn,O_RDWR)) == -1)
|
||
|
|
perror("open() error");
|
||
|
|
else {
|
||
|
|
if (write(fd1, out, strlen(out)+1) == -1) {
|
||
|
|
perror("write() error");
|
||
|
|
write_error = 1;
|
||
|
|
}
|
||
|
|
close(fd1);
|
||
|
|
if (!write_error) {
|
||
|
|
if (read(fd2, in, sizeof(in)) == -1)
|
||
|
|
perror("read() error");
|
||
|
|
else printf("string read from file was: '%s'\n", in);
|
||
|
|
}
|
||
|
|
close(fd2);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p><strong>Output:</strong></p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
string read from file was: 'Test string'
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
API introduced: V3R1
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<center>
|
||
|
|
<table cellpadding="2" cellspacing="2">
|
||
|
|
<tr align="center">
|
||
|
|
<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
|
||
|
|
"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
</center>
|
||
|
|
</body>
|
||
|
|
</html>
|
||
|
|
|