ibm-information-center/dist/eclipse/plugins/i5OS.ic.apis_5.4.0.1/settod.htm

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<title>settimeofday()--Set System Clock</title>
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<h2>settimeofday()--Set System Clock</h2>
<div class="box" style="width: 60%;">
<br>
&nbsp;&nbsp;Syntax<br>
<pre>
#include &lt;sys/time.h&gt;
int settimeofday (struct timeval *<var>tp</var>,
struct timezone *<var>tzp</var>);
</pre>
<br>
&nbsp;&nbsp;Service Program Name: QWCTZUTC<br>
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<br>
&nbsp;&nbsp;Default Public Authority: *USE<br>
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&nbsp;&nbsp;Threadsafe: Yes<br>
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<br>
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<p>The <strong>settimeofday()</strong> function sets the system clock to the Coordinated Universal Time (UTC) contained in the timeval structure pointed to by <var>tp</var>. The
<var>tzp</var> parameter is not used.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>tp</strong></dt>
<dd>(Input) A pointer to a timeval structure that contains the time in seconds
and microseconds since 1 January 1970, 00:00:00 UTC (epoch-1970).<br>
<br>
</dd>
<dt><strong>tzp</strong></dt>
<dd>This parameter is not used.</dd>
</dl>
<br>
<h3>Authorities and Locks</h3>
<dl>
<dt><em>Special Authority</em></dt>
<dd>*ALLOBJ</dd>
</dl>
<br>
<h3>Return Value</h3>
<table cellpadding="5">
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<tr>
<td align="left" valign="top"><em>0</em></td>
<td align="left" valign="top"><strong>settimeofday()</strong> was successful.</td>
</tr><tr>
<td align="left" valign="top"><em>-1</em></td>
<td align="left" valign="top"><strong>settimeofday()</strong> was not successful. The <var>errno</var>
variable is set to indicate the error.</td>
</tr>
</table>
<br>
<h3>Error Conditions</h3>
<p>If <strong>settimeofday()</strong> is not successful, <var>errno</var>
usually indicates one of the following errors. Under some conditions,
<var>errno</var> could indicate an error other than those listed here.</p>
<table cellpadding="5">
<!-- cols="15 85" -->
<tr>
<td align="left" valign="top"><em>[EACCES]</em></td>
<td align="left" valign="top">Permission denied.
<p>An attempt was made to access an object in a way forbidden by its object
access permissions.</p>
</td>
</tr>
<tr>
<td align="left" valign="top"><em>[EINVAL]</em></td>
<td align="left" valign="top">An invalid parameter was found.
<p>A parameter passed to this function is not valid.</p>
</td>
</tr>
<tr>
<td align="left" valign="top"><em>[EFAULT]</em></td>
<td align="left" valign="top">The address used for an argument is not correct.
<p>In attempting to use an argument in a call, the system detected an address
that is not valid.</p>
<p>While attempting to access a parameter passed to this function, the system
detected an address that is not valid.</p>
</td>
</tr>
<tr>
<td align="left" valign="top"><em>[EPERM]</em></td>
<td align="left" valign="top">Operation not permitted.
<p>You must have appropriate privileges or be the owner of the object or other
resource to do the requested operation.</p>
</td>
</tr>
<tr>
<td align="left" valign="top"><em>[EUNKNOWN]</em></td>
<td align="left" valign="top">Unknown system state.
<p>The operation failed because of an unknown system state. See any messages in
the job log and correct any errors that are indicated, then retry the
operation.</p>
</td>
</tr>
</table>
<br>
<br>
<h3>Error Messages</h3>
<p>None.</p>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>sys/time.h</strong>&gt; file (see <a href=
"unix13.htm">Header Files for UNIX-Type Functions</a>)<br>
<br>
</li>
<li><a href="adjtime.htm">adjtime()--Adjust System Clock</a><br>
<br>
</li>
<li><a href="gettod.htm">gettimeofday()--Get Current UTC Time</a></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 sets the system clock:</p>
<pre>
#include &lt;sys/time.h&gt;
#include &lt;stdio.h&gt;
#include &lt;errno.h&gt;
int main(int argc, char *argv[])
{
struct timeval now;
int rc;
now.tv_sec=866208142;
now.tv_usec=290944;
rc=settimeofday(&amp;now, NULL);
if(rc==0) {
printf(&quot;settimeofday() successful.\n&quot;);
}
else {
printf(&quot;settimeofday() failed, &quot;
&quot;errno = %d\n&quot;,errno);
return -1;
}
return 0;
}
</pre>
<strong>Example Output:</strong>
<pre>
settimeofday() successful.
</pre>
<br>
<hr>
API introduced: V4R2
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