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<h1 class="settitle" align="center">Ntp-wait User’s Manual</h1>
<span id="Top"></span><div class="header">
<p>
Previous: <a href="dir.html#Top" accesskey="p" rel="prev">(dir)</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> </p>
</div>
<h1 class="node-heading">Top</h1>
<p>This document describes the use of the NTP Project’s <code>ntp-wait</code> program.
</p>
<p>If there are time-sensitive applications,
the proper sequence of events is to
run <code>ntpd -g</code> as early as possible,
then invoke all of the non-time-sensitive process,
run <code>ntp-wait</code> to block
until the system’s time has stabilized and synchronized,
and only then start any applicaitons (like database servers) that require
accurate and stable time.
</p>
<p>This document applies to version 4.2.8p18 of <code>ntp-wait</code>.
</p>
<span id="SEC_Overview"></span>
<h2 class="shortcontents-heading">Short Table of Contents</h2>
<div class="shortcontents">
<li><a id="stoc-Invoking-ntp_002dwait" href="#toc-Invoking-ntp_002dwait">1 Invoking ntp-wait</a></li>
</div>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• ntp-wait Description</td><td> </td><td align="left" valign="top">Description
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Invocation" accesskey="2">ntp-wait Invocation</a></td><td> </td><td align="left" valign="top">Invoking ntp-wait
</td></tr>
</table>
<hr>
<span id="ntp_002dwait-Invocation"></span><div class="header">
<p>
Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p>
</div>
<span id="Invoking-ntp_002dwait"></span><h3 class="section">1 Invoking ntp-wait</h3>
<span id="index-ntp_002dwait"></span>
<span id="index-Wait-for-ntpd-to-stabilize-the-system-clock"></span>
<p><code>ntp-wait</code>
will send at most
<kbd>num-tries</kbd>
queries to
<code>ntpd(8)</code>,
sleeping for
<kbd>secs-between-tries</kbd>
after each status return that says
<code>ntpd(8)</code>
has not yet produced a synchronized and stable system clock.
</p>
<p><code>ntp-wait</code>
will do this quietly, unless the
<code>-v</code>
flag is provided.
This can be useful at boot time, to delay the boot sequence until after
<kbd>ntpd</kbd> <kbd>-g</kbd>
has set the time.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntp-wait</code> program.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-usage" accesskey="1">ntp-wait usage</a></td><td> </td><td align="left" valign="top">ntp-wait help/usage (<samp>--help</samp>)
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-tries" accesskey="2">ntp-wait tries</a></td><td> </td><td align="left" valign="top">tries option (-n)
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-sleep" accesskey="3">ntp-wait sleep</a></td><td> </td><td align="left" valign="top">sleep option (-s)
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-verbose" accesskey="4">ntp-wait verbose</a></td><td> </td><td align="left" valign="top">verbose option (-v)
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-exit-status" accesskey="5">ntp-wait exit status</a></td><td> </td><td align="left" valign="top">exit status
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Authors" accesskey="6">ntp-wait Authors</a></td><td> </td><td align="left" valign="top">Authors
</td></tr>
<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Notes" accesskey="7">ntp-wait Notes</a></td><td> </td><td align="left" valign="top">Notes
</td></tr>
</table>
<hr>
<span id="ntp_002dwait-usage"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-tries" accesskey="n" rel="next">ntp-wait tries</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="ntp_002dwait-help_002fusage-_0028_002d_002dhelp_0029"></span><h4 class="subsection">1.1 ntp-wait help/usage (<samp>--help</samp>)</h4>
<span id="index-ntp_002dwait-help"></span>
<p>This is the automatically generated usage text for ntp-wait.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>). <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function. The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>. Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">ntp-wait - Wait for ntpd to stabilize the system clock - Ver. 4.2.8p18
USAGE: ntp-wait [ -<flag> [<val>] | --<name>[{=| }<val>] ]...
-n, --tries=num Number of times to check ntpd
-s, --sleep=num How long to sleep between tries
-v, --verbose Be verbose
-?, --help Display usage information and exit
--more-help Pass the extended usage text through a pager
Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
</pre></div>
<hr>
<span id="ntp_002dwait-tries"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-sleep" accesskey="n" rel="next">ntp-wait sleep</a>, Previous: <a href="#ntp_002dwait-usage" accesskey="p" rel="prev">ntp-wait usage</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="tries-option-_0028_002dn_0029"></span><h4 class="subsection">1.2 tries option (-n)</h4>
<span id="index-ntp_002dwait_002dtries"></span>
<p>This is the “number of times to check ntpd” option.
This option takes a number argument.
The maximum number of times we will check <code>ntpd</code> to see if
it has been able to synchronize and stabilize the system clock.
</p><hr>
<span id="ntp_002dwait-sleep"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-verbose" accesskey="n" rel="next">ntp-wait verbose</a>, Previous: <a href="#ntp_002dwait-tries" accesskey="p" rel="prev">ntp-wait tries</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="sleep-option-_0028_002ds_0029"></span><h4 class="subsection">1.3 sleep option (-s)</h4>
<span id="index-ntp_002dwait_002dsleep"></span>
<p>This is the “how long to sleep between tries” option.
This option takes a number argument <samp>secs-between-tries</samp>.
We will sleep for <samp>secs-between-tries</samp> after each query
of <code>ntpd</code> that returns "the time is not yet stable".
</p><hr>
<span id="ntp_002dwait-verbose"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-exit-status" accesskey="n" rel="next">ntp-wait exit status</a>, Previous: <a href="#ntp_002dwait-sleep" accesskey="p" rel="prev">ntp-wait sleep</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="verbose-option-_0028_002dv_0029"></span><h4 class="subsection">1.4 verbose option (-v)</h4>
<span id="index-ntp_002dwait_002dverbose"></span>
<p>This is the “be verbose” option.
By default, <code>ntp-wait</code> is silent.
With this option, <code>ntp-wait</code> will provide status information.
</p><hr>
<span id="ntp_002dwait-exit-status"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-Authors" accesskey="n" rel="next">ntp-wait Authors</a>, Previous: <a href="#ntp_002dwait-verbose" accesskey="p" rel="prev">ntp-wait verbose</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="ntp_002dwait-exit-status-1"></span><h4 class="subsection">1.5 ntp-wait exit status</h4>
<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>‘<samp>0 (EXIT_SUCCESS)</samp>’</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>‘<samp>1 (EXIT_FAILURE)</samp>’</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<hr>
<span id="ntp_002dwait-Authors"></span><div class="header">
<p>
Next: <a href="#ntp_002dwait-Notes" accesskey="n" rel="next">ntp-wait Notes</a>, Previous: <a href="#ntp_002dwait-exit-status" accesskey="p" rel="prev">ntp-wait exit status</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="ntp_002dwait-Authors-1"></span><h4 class="subsection">1.6 ntp-wait Authors</h4>
<hr>
<span id="ntp_002dwait-Notes"></span><div class="header">
<p>
Previous: <a href="#ntp_002dwait-Authors" accesskey="p" rel="prev">ntp-wait Authors</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p>
</div>
<span id="ntp_002dwait-Notes-1"></span><h4 class="subsection">1.7 ntp-wait Notes</h4>
<hr>
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