558 lines
12 KiB
HTML
558 lines
12 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>fsync()--Synchronize Changes to File</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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<!-- 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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<!-- 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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<!-- 020618 EMIG Updates for NFS threadsafety, V5R3 -->
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<!-- 020514 JET This file has undergone html cleanup -->
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<!-- 020718 MFENLON: updated for QFileSvr.400 threadsafety, V5R3 -->
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<!-- 020918 Rosckes: Added ENOTAVAIL errno description, V5R3 -->
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<!-- 050328 JTROUS: fix enums, no change flag, V5R4 -->
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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 --><!-- 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>fsync()--Synchronize Changes to File</h2>
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<div class="box" style="width: 70%;">
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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 fsync(int <em>file_descriptor</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 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>fsync()</strong> function transfers all data for the file
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indicated by the open file descriptor <em>file_descriptor</em> to the storage
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device associated with <em>file_descriptor</em>. <strong>fsync()</strong> does
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not return until the transfer is complete, or until an error is detected.</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>file_descriptor</em></strong></dt>
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<dd>(Input) The file descriptor of the file that is to have its modified data
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written to permanent storage.</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> or <strong>creat()</strong>.</p>
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<br>
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<h3>Return Value</h3>
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<dl compact>
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<dt><em>0</em></dt>
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<dd><strong>fsync()</strong> was successful.</dd>
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<dt><em>-1</em></dt>
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<dd><strong>fsync()</strong> was not successful. The <em>errno</em> global
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variable is set to indicate the error.</dd>
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</dl>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>fsync()</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#EINVAL">EINVAL</a>]</em></td>
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<td align="left" valign="top">
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<p>For example, the file type is not valid for this operation.</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#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><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#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#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>If interaction with a file server is required to access the object, <em>
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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>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ECONNREFUSED">ECONNREFUSED</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#ECONNRESET">ECONNRESET</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#EHOSTDOWN">EHOSTDOWN</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#EHOSTUNREACH">EHOSTUNREACH</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#ENETDOWN">ENETDOWN</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#ENETRESET">ENETRESET</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#ENETUNREACH">ENETUNREACH</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#ETIMEDOUT">ETIMEDOUT</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#EUNATCH">EUNATCH</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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||
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<p>The following messages may be sent from this function:</p>
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<table width="100%">
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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>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td width="15%" valign="top">CPE3418 E</td>
|
||
|
|
<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPFA0D4 E</td>
|
||
|
|
<td valign="top">File system error occurred. Error number &1.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPF3CF2 E</td>
|
||
|
|
<td valign="top">Error(s) occurred during running of &1 API.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPF9872 E</td>
|
||
|
|
<td valign="top">Program or service program &1 in library &2 ended.
|
||
|
|
Reason code &3.</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<h3><a name="usage_notes">Usage Notes</a></h3>
|
||
|
|
|
||
|
|
<ol type="1">
|
||
|
|
<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.<br>
|
||
|
|
</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>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
</ul>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>Using this function on a character special file will result in a return
|
||
|
|
value of -1 and the errno global value set to EINVAL.</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>)<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>
|
||
|
|
<a href="fclear.htm">fclear()</a>--Write (Binary Zeros) to Descriptor<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="fclear64.htm">fclear64()</a>--Write (Binary Zeros) to Descriptor (Large File Enabled)
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="open.htm">open()</a>--Open File<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="write.htm">write()</a>--Write to Descriptor</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>fsync()</strong>:</p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
#include <unistd.h>
|
||
|
|
#include <sys/types.h>
|
||
|
|
#include <sys/stat.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
|
||
|
|
#define mega_string_len 250000
|
||
|
|
|
||
|
|
main() {
|
||
|
|
char *mega_string;
|
||
|
|
int file_descriptor;
|
||
|
|
int ret;
|
||
|
|
char fn[]="fsync.file";
|
||
|
|
|
||
|
|
if ((mega_string = (char*) malloc(mega_string_len)) == NULL)
|
||
|
|
perror("malloc() error");
|
||
|
|
else if ((file_descriptor = creat(fn, S_IWUSR)) < 0)
|
||
|
|
perror("creat() error");
|
||
|
|
else {
|
||
|
|
memset(mega_string, 's', mega_string_len);
|
||
|
|
if ((ret = write(file_descriptor,
|
||
|
|
mega_string, mega_string_len)) == -1)
|
||
|
|
perror("write() error");
|
||
|
|
else {
|
||
|
|
printf("write() wrote %d bytes\n", ret);
|
||
|
|
if (fsync(file_descriptor) != 0)
|
||
|
|
perror("fsync() error");
|
||
|
|
else if ((ret = write(file_descriptor,
|
||
|
|
mega_string, mega_string_len)) == -1)
|
||
|
|
perror("write() error");
|
||
|
|
else
|
||
|
|
printf("write() wrote %d bytes\n", ret);
|
||
|
|
}
|
||
|
|
close(file_descriptor);
|
||
|
|
unlink(fn);
|
||
|
|
}
|
||
|
|
free(mega_string);
|
||
|
|
}
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p><strong>Output:</strong></p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
write() wrote 250000 bytes
|
||
|
|
write() wrote 250000 bytes
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<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>
|
||
|
|
|