232 lines
6.4 KiB
HTML
232 lines
6.4 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<!-- Begin Header records -->
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<title>adjtime()--Adjust System Clock</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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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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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 type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>adjtime()--Adjust System Clock</h2>
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<div class="box" style="width: 70%;">
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<br>
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Syntax
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<pre>
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#include <sys/time.h>
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int adjtime (struct timeval *delta,
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struct timeval *olddelta);
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</pre>
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<br>
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Service Program Name: QWCTZUTC<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>adjtime()</strong> function makes small adjustments to the system clock, either slowing it down or speeding it up by the time specified in the <em>delta</em> parameter up to a maximum of two hours. If <em>delta</em> is negative, the clock is slowed down by incrementing it more slowly than normal until the correction is complete. If <em>delta</em> is positive, the clock is sped up by incrementing it more quickly than normal until the correction is complete. If <em>olddelta</em> is not NULL, the amount of time still to be corrected from a previous <strong>adjtime()</strong> call is returned in the structure it points to.
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</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>delta</strong></dt>
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<dd>(Input)
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<p>A pointer to a timeval structure that contains the amount of time for adjusting the clock.</p>
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</dd>
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<dt><strong>olddelta</strong></dt>
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<dd>(Output)
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<p>A pointer to a timeval structure that contains the amount of time still to be corrected from a previous call to <strong>adjtime()</strong>.</p>
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</dd>
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</dl>
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<br>
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<h3>Authorities and Locks</h3>
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<dl>
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<dt><em>Special Authority</em></dt>
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<dd>*ALLOBJ<br>
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<br>
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</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 width="5%" valign=top><strong>0</strong></td>
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<td width="95%"><strong>adjtime()</strong> was successful. The requested adjustment was initiated and the value returned in the structure pointed to by the <em>olddelta</em> parameter is the amount of time still to be corrected from a previous <strong>adjtime()</strong>.</td>
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</tr>
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<tr>
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<td valign=top><strong>-1</strong></td>
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<td><strong>adjtime()</strong> was not successful. The <em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>adjtime()</strong> is not successful, <em>errno</em> usually indicates one of the following errors. Under some conditions, <em>errno</em> could indicate an error other than those listed here.</p>
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><em>[EACCES]</em></td>
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<td align="left" valign="top">Permission denied.
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<p>An attempt was made to access an object in a way forbidden by its object
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access permissions.</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"><em>[EINVAL]</em></td>
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<td align="left" valign="top">An invalid parameter was found.
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<p>A parameter passed to this function is not valid.</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"><em>[EFAULT]</em></td>
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<td align="left" valign="top">The address used for an argument is not correct.
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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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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EPERM]</em></td>
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<td align="left" valign="top">Operation not permitted.
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<p>You must have appropriate privileges or be the owner of the object or other
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resource to do the requested 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"><em>[ENOTSUP]</em></td>
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<td align="left" valign="top">Operation not supported.
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<p>The operation is not supported.</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"><em>[EUNKNOWN]</em></td>
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<td align="left" valign="top">Unknown system state.
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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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</td>
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</tr>
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</table>
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<br>
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<h3>Error Messages</h3>
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<p>None.</p>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>sys/time.h</strong>> file (see <a href=
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"unix13.htm">Header Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="gettod.htm">gettimeofday()--Get Current UTC Time</a><br>
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<br>
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</li>
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<li><a href="settod.htm">settimeofday()--Set System Clock</a></li>
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</ul>
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<br>
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<h3><a name="example.htm">Example</a></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 initiates a system clock adjustment:</p>
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<pre>
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#include <sys/time.h>
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#include <stdio.h>
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#include <errno.h>
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int main(int argc, char *argv[])
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{
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struct timeval adj, old;
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int rc;
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/* Speed up the clock by 1.5 seconds. */
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adj.tv_sec=1;
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adj.tv_usec=500000;
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rc=adjtime(&adj, &old);
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if(rc==0) {
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printf("adjtime() successful. "
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"Olddelta = %u.%06u\n",
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old.tv_sec, old.tv_usec);
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}
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else {
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printf("adjtime() failed, errno = %d\n",errno);
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return -1;
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}
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return 0;
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}
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</pre>
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<strong>Example Output:</strong>
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<pre>
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adjtime() successful. Olddelta = 0.000000
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</pre>
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<br>
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<hr>
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API introduced: V4R2
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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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