052d159a8b
4.2.8p12 --> 4.2.8p13 MFC after: immediately Security: CVE-2019-8936 VuXML: c2576e14-36e2-11e9-9eda-206a8a720317 Obtained from: nwtime.org
703 lines
31 KiB
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703 lines
31 KiB
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</head>
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<body lang="en">
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<h1 class="settitle" align="center">Sntp User’s Manual</h1>
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<a name="Top"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-Description" accesskey="n" rel="next">sntp Description</a>, 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>
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</div>
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<a name="Simple-Network-Time-Protocol-User-Manual"></a>
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<h1 class="top">Simple Network Time Protocol User Manual</h1>
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<p>This document describes the use of the NTP Project’s <code>sntp</code> program,
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that can be used to query a Network Time Protocol (NTP) server and
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display the time offset of the system clock relative to the server
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clock. Run as root, it can correct the system clock to this offset as
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well. It can be run as an interactive command or from a cron job.
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</p>
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<p>This document applies to version 4.2.8p13 of <code>sntp</code>.
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</p>
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<p>The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
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IETF specification.
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</p>
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<a name="SEC_Overview"></a>
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<h2 class="shortcontents-heading">Short Table of Contents</h2>
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<div class="shortcontents">
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<ul class="no-bullet">
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<li><a name="stoc-Description" href="#toc-Description">1 Description</a></li>
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</ul>
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</div>
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<table class="menu" border="0" cellspacing="0">
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<tr><td align="left" valign="top">• <a href="#sntp-Description" accesskey="1">sntp Description</a>:</td><td> </td><td align="left" valign="top">Description
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-Invocation" accesskey="2">sntp Invocation</a>:</td><td> </td><td align="left" valign="top">Invoking sntp
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#Usage" accesskey="3">Usage</a>:</td><td> </td><td align="left" valign="top">Usage
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</td></tr>
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</table>
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<hr>
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<a name="sntp-Description"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-Invocation" accesskey="n" rel="next">sntp Invocation</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p>
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</div>
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<a name="Description"></a>
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<h2 class="chapter">1 Description</h2>
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<p>By default, <code>sntp</code> writes the local data and time (i.e., not UTC) to the
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standard output in the format:
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</p>
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<div class="example">
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<pre class="example">1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
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</pre></div>
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<p>where
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YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
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(+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC),
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and
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the +4.567 +/- 0.089 secs indicates the time offset and
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error bound of the system clock relative to the server clock.
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</p>
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<table class="menu" border="0" cellspacing="0">
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<tr><td align="left" valign="top">• <a href="#sntp-Invocation" accesskey="1">sntp Invocation</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#Usage" accesskey="2">Usage</a>:</td><td> </td><td align="left" valign="top">
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</td></tr>
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</table>
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<hr>
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<a name="sntp-Invocation"></a>
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<div class="header">
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<p>
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Next: <a href="#Usage" accesskey="n" rel="next">Usage</a>, Previous: <a href="#sntp-Description" accesskey="p" rel="prev">sntp Description</a>, Up: <a href="#sntp-Description" accesskey="u" rel="up">sntp Description</a> </p>
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</div>
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<a name="Invoking-sntp"></a>
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<h3 class="section">1.1 Invoking sntp</h3>
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<a name="index-sntp"></a>
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<a name="index-standard-Simple-Network-Time-Protocol-client-program"></a>
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<p><code>sntp</code>
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can be used as an SNTP client to query a NTP or SNTP server and either display
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the time or set the local system’s time (given suitable privilege). It can be
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run as an interactive command or from a
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<code>cron</code>
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job.
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</p>
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<p>NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
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are defined and described by RFC 5905.
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</p>
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<p>The default is to write the estimated correct local date and time (i.e. not
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UTC) to the standard output in a format like:
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</p>
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<p><code>'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'</code>
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</p>
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<p>where the
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<code>'(+0800)'</code>
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means that to get to UTC from the reported local time one must
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add 8 hours and 0 minutes,
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the
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<code>'+4.567'</code>
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indicates the local clock is 4.567 seconds behind the correct time
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(so 4.567 seconds must be added to the local clock to get it to be correct).
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Note that the number of decimals printed for this value will change
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based on the reported precision of the server.
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<code>'+/- 0.089'</code>
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is the reported
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<em>synchronization</em> <em>distance</em>
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(in seconds), which represents the maximum error due to all causes.
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If the server does not report valid data needed to calculate the
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synchronization distance, this will be reported as
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<code>'+/- ?'</code>.
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If the
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<em>host</em>
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is different from the
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<em>IP</em>,
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both will be displayed.
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Otherwise, only the
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<em>IP</em>
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is displayed.
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Finally, the
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<em>stratum</em>
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of the host is reported
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and the leap indicator is decoded and displayed.
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</p>
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<p>This section was generated by <strong>AutoGen</strong>,
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using the <code>agtexi-cmd</code> template and the option descriptions for the <code>sntp</code> program.
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This software is released under the NTP license, <http://ntp.org/license>.
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</p>
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<table class="menu" border="0" cellspacing="0">
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<tr><td align="left" valign="top">• <a href="#sntp-usage" accesskey="1">sntp usage</a>:</td><td> </td><td align="left" valign="top">sntp help/usage (<samp>--help</samp>)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-ipv4" accesskey="2">sntp ipv4</a>:</td><td> </td><td align="left" valign="top">ipv4 option (-4)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-ipv6" accesskey="3">sntp ipv6</a>:</td><td> </td><td align="left" valign="top">ipv6 option (-6)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-authentication" accesskey="4">sntp authentication</a>:</td><td> </td><td align="left" valign="top">authentication option (-a)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-broadcast" accesskey="5">sntp broadcast</a>:</td><td> </td><td align="left" valign="top">broadcast option (-b)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-concurrent" accesskey="6">sntp concurrent</a>:</td><td> </td><td align="left" valign="top">concurrent option (-c)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-gap" accesskey="7">sntp gap</a>:</td><td> </td><td align="left" valign="top">gap option (-g)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-kod" accesskey="8">sntp kod</a>:</td><td> </td><td align="left" valign="top">kod option (-K)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-keyfile" accesskey="9">sntp keyfile</a>:</td><td> </td><td align="left" valign="top">keyfile option (-k)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-logfile">sntp logfile</a>:</td><td> </td><td align="left" valign="top">logfile option (-l)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-steplimit">sntp steplimit</a>:</td><td> </td><td align="left" valign="top">steplimit option (-M)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-ntpversion">sntp ntpversion</a>:</td><td> </td><td align="left" valign="top">ntpversion option (-o)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-usereservedport">sntp usereservedport</a>:</td><td> </td><td align="left" valign="top">usereservedport option (-r)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-timeout">sntp timeout</a>:</td><td> </td><td align="left" valign="top">timeout option (-t)
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-wait">sntp wait</a>:</td><td> </td><td align="left" valign="top">wait option
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-config">sntp config</a>:</td><td> </td><td align="left" valign="top">presetting/configuring sntp
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-exit-status">sntp exit status</a>:</td><td> </td><td align="left" valign="top">exit status
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-Usage">sntp Usage</a>:</td><td> </td><td align="left" valign="top">Usage
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</td></tr>
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<tr><td align="left" valign="top">• <a href="#sntp-Authors">sntp Authors</a>:</td><td> </td><td align="left" valign="top">Authors
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</td></tr>
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</table>
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<hr>
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<a name="sntp-usage"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-ipv4" accesskey="n" rel="next">sntp ipv4</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
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</div>
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<a name="sntp-help_002fusage-_0028_002d_002dhelp_0029"></a>
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<h4 class="subsection">1.1.1 sntp help/usage (<samp>--help</samp>)</h4>
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<a name="index-sntp-help"></a>
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<p>This is the automatically generated usage text for sntp.
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</p>
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<p>The text printed is the same whether selected with the <code>help</code> option
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(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>). <code>more-help</code> will print
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the usage text by passing it through a pager program.
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<code>more-help</code> is disabled on platforms without a working
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<code>fork(2)</code> function. The <code>PAGER</code> environment variable is
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used to select the program, defaulting to <samp>more</samp>. Both will exit
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with a status code of 0.
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</p>
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<div class="example">
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<pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.8p13
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Usage: sntp [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
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[ hostname-or-IP ...]
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Flg Arg Option-Name Description
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-4 no ipv4 Force IPv4 DNS name resolution
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- prohibits the option 'ipv6'
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-6 no ipv6 Force IPv6 DNS name resolution
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- prohibits the option 'ipv4'
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-a Num authentication Enable authentication with the key auth-keynumber
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-b Str broadcast Listen to the address specified for broadcast time sync
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- may appear multiple times
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-c Str concurrent Concurrently query all IPs returned for host-name
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- may appear multiple times
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-d no debug-level Increase debug verbosity level
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- may appear multiple times
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-D Num set-debug-level Set the debug verbosity level
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- may appear multiple times
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-g Num gap The gap (in milliseconds) between time requests
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-K Fil kod KoD history filename
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-k Fil keyfile Look in this file for the key specified with -a
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-l Fil logfile Log to specified logfile
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-M Num steplimit Adjustments less than steplimit msec will be slewed
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- it must be in the range:
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greater than or equal to 0
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-o Num ntpversion Send int as our NTP protocol version
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- it must be in the range:
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0 to 7
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-r no usereservedport Use the NTP Reserved Port (port 123)
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-S no step OK to 'step' the time with settimeofday(2)
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-s no slew OK to 'slew' the time with adjtime(2)
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-t Num timeout The number of seconds to wait for responses
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no wait Wait for pending replies (if not setting the time)
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- disabled as '--no-wait'
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- enabled by default
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opt version output version information and exit
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-? no help display extended usage information and exit
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-! no more-help extended usage information passed thru pager
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-> opt save-opts save the option state to a config file
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-< Str load-opts load options from a config file
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- disabled as '--no-load-opts'
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- may appear multiple times
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Options are specified by doubled hyphens and their name or by a single
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hyphen and the flag character.
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The following option preset mechanisms are supported:
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- reading file $HOME/.ntprc
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- reading file ./.ntprc
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- examining environment variables named SNTP_*
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Please send bug reports to: <http://bugs.ntp.org, bugs@ntp.org>
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</pre></div>
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<hr>
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<a name="sntp-ipv4"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-ipv6" accesskey="n" rel="next">sntp ipv6</a>, Previous: <a href="#sntp-usage" accesskey="p" rel="prev">sntp usage</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
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</div>
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<a name="ipv4-option-_0028_002d4_0029"></a>
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<h4 class="subsection">1.1.2 ipv4 option (-4)</h4>
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<a name="index-sntp_002dipv4"></a>
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<p>This is the “force ipv4 dns name resolution” option.
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</p>
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<p>This option has some usage constraints. It:
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</p><ul>
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<li> must not appear in combination with any of the following options:
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ipv6.
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</li></ul>
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<p>Force DNS resolution of the following host names on the command line
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to the IPv4 namespace.
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</p><hr>
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<a name="sntp-ipv6"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-authentication" accesskey="n" rel="next">sntp authentication</a>, Previous: <a href="#sntp-ipv4" accesskey="p" rel="prev">sntp ipv4</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
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</div>
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<a name="ipv6-option-_0028_002d6_0029"></a>
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<h4 class="subsection">1.1.3 ipv6 option (-6)</h4>
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<a name="index-sntp_002dipv6"></a>
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<p>This is the “force ipv6 dns name resolution” option.
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</p>
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<p>This option has some usage constraints. It:
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</p><ul>
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<li> must not appear in combination with any of the following options:
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ipv4.
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</li></ul>
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<p>Force DNS resolution of the following host names on the command line
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to the IPv6 namespace.
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</p><hr>
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<a name="sntp-authentication"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-broadcast" accesskey="n" rel="next">sntp broadcast</a>, Previous: <a href="#sntp-ipv6" accesskey="p" rel="prev">sntp ipv6</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
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</div>
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<a name="authentication-option-_0028_002da_0029"></a>
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<h4 class="subsection">1.1.4 authentication option (-a)</h4>
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<a name="index-sntp_002dauthentication"></a>
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<p>This is the “enable authentication with the key <var>auth-keynumber</var>” option.
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This option takes a number argument <samp>auth-keynumber</samp>.
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Enable authentication using the key specified in this option’s
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argument. The argument of this option is the <samp>keyid</samp>, a
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number specified in the <samp>keyfile</samp> as this key’s identifier.
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See the <samp>keyfile</samp> option (<samp>-k</samp>) for more details.
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</p><hr>
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<a name="sntp-broadcast"></a>
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<div class="header">
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<p>
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Next: <a href="#sntp-concurrent" accesskey="n" rel="next">sntp concurrent</a>, Previous: <a href="#sntp-authentication" accesskey="p" rel="prev">sntp authentication</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
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</div>
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<a name="broadcast-option-_0028_002db_0029"></a>
|
|
<h4 class="subsection">1.1.5 broadcast option (-b)</h4>
|
|
<a name="index-sntp_002dbroadcast"></a>
|
|
|
|
<p>This is the “listen to the address specified for broadcast time sync” option.
|
|
This option takes a string argument <samp>broadcast-address</samp>.
|
|
</p>
|
|
<p>This option has some usage constraints. It:
|
|
</p><ul>
|
|
<li> may appear an unlimited number of times.
|
|
</li></ul>
|
|
|
|
<p>If specified <code>sntp</code> will listen to the specified address
|
|
for NTP broadcasts. The default maximum wait time
|
|
can (and probably should) be modified with <samp>-t</samp>.
|
|
</p><hr>
|
|
<a name="sntp-concurrent"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-gap" accesskey="n" rel="next">sntp gap</a>, Previous: <a href="#sntp-broadcast" accesskey="p" rel="prev">sntp broadcast</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="concurrent-option-_0028_002dc_0029"></a>
|
|
<h4 class="subsection">1.1.6 concurrent option (-c)</h4>
|
|
<a name="index-sntp_002dconcurrent"></a>
|
|
|
|
<p>This is the “concurrently query all ips returned for host-name” option.
|
|
This option takes a string argument <samp>host-name</samp>.
|
|
</p>
|
|
<p>This option has some usage constraints. It:
|
|
</p><ul>
|
|
<li> may appear an unlimited number of times.
|
|
</li></ul>
|
|
|
|
<p>Requests from an NTP "client" to a "server" should never be sent
|
|
more rapidly than one every 2 seconds. By default, any IPs returned
|
|
as part of a DNS lookup are assumed to be for a single instance of
|
|
<code>ntpd</code>, and therefore <code>sntp</code> will send queries to these IPs
|
|
one after another, with a 2-second gap in between each query.
|
|
</p>
|
|
<p>The <samp>-c</samp> or <samp>--concurrent</samp> flag says that any IPs
|
|
returned for the DNS lookup of the supplied host-name are on
|
|
different machines, so we can send concurrent queries.
|
|
</p><hr>
|
|
<a name="sntp-gap"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-kod" accesskey="n" rel="next">sntp kod</a>, Previous: <a href="#sntp-concurrent" accesskey="p" rel="prev">sntp concurrent</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="gap-option-_0028_002dg_0029"></a>
|
|
<h4 class="subsection">1.1.7 gap option (-g)</h4>
|
|
<a name="index-sntp_002dgap"></a>
|
|
|
|
<p>This is the “the gap (in milliseconds) between time requests” option.
|
|
This option takes a number argument <samp>milliseconds</samp>.
|
|
Since we’re only going to use the first valid response we get and
|
|
there is benefit to specifying a good number of servers to query,
|
|
separate the queries we send out by the specified number of
|
|
milliseconds.
|
|
</p><hr>
|
|
<a name="sntp-kod"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-keyfile" accesskey="n" rel="next">sntp keyfile</a>, Previous: <a href="#sntp-gap" accesskey="p" rel="prev">sntp gap</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="kod-option-_0028_002dK_0029"></a>
|
|
<h4 class="subsection">1.1.8 kod option (-K)</h4>
|
|
<a name="index-sntp_002dkod"></a>
|
|
|
|
<p>This is the “kod history filename” option.
|
|
This option takes a file argument <samp>file-name</samp>.
|
|
Specifies the filename to be used for the persistent history of KoD
|
|
responses received from servers. If the file does not exist, a
|
|
warning message will be displayed. The file will not be created.
|
|
</p><hr>
|
|
<a name="sntp-keyfile"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-logfile" accesskey="n" rel="next">sntp logfile</a>, Previous: <a href="#sntp-kod" accesskey="p" rel="prev">sntp kod</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="keyfile-option-_0028_002dk_0029"></a>
|
|
<h4 class="subsection">1.1.9 keyfile option (-k)</h4>
|
|
<a name="index-sntp_002dkeyfile"></a>
|
|
|
|
<p>This is the “look in this file for the key specified with <samp>-a</samp>” option.
|
|
This option takes a file argument <samp>file-name</samp>.
|
|
This option specifies the keyfile.
|
|
<code>sntp</code> will search for the key specified with <samp>-a</samp>
|
|
<samp>keyno</samp> in this file. See <code>ntp.keys(5)</code> for more
|
|
information.
|
|
</p><hr>
|
|
<a name="sntp-logfile"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-steplimit" accesskey="n" rel="next">sntp steplimit</a>, Previous: <a href="#sntp-keyfile" accesskey="p" rel="prev">sntp keyfile</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="logfile-option-_0028_002dl_0029"></a>
|
|
<h4 class="subsection">1.1.10 logfile option (-l)</h4>
|
|
<a name="index-sntp_002dlogfile"></a>
|
|
|
|
<p>This is the “log to specified logfile” option.
|
|
This option takes a file argument <samp>file-name</samp>.
|
|
This option causes the client to write log messages to the specified
|
|
<samp>logfile</samp>.
|
|
</p><hr>
|
|
<a name="sntp-steplimit"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-ntpversion" accesskey="n" rel="next">sntp ntpversion</a>, Previous: <a href="#sntp-logfile" accesskey="p" rel="prev">sntp logfile</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="steplimit-option-_0028_002dM_0029"></a>
|
|
<h4 class="subsection">1.1.11 steplimit option (-M)</h4>
|
|
<a name="index-sntp_002dsteplimit"></a>
|
|
|
|
<p>This is the “adjustments less than <var>steplimit</var> msec will be slewed” option.
|
|
This option takes a number argument.
|
|
If the time adjustment is less than <samp>steplimit</samp> milliseconds,
|
|
slew the amount using <code>adjtime(2)</code>. Otherwise, step the
|
|
correction using <code>settimeofday(2)</code>. The default value is 0,
|
|
which means all adjustments will be stepped. This is a feature, as
|
|
different situations demand different values.
|
|
</p><hr>
|
|
<a name="sntp-ntpversion"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-usereservedport" accesskey="n" rel="next">sntp usereservedport</a>, Previous: <a href="#sntp-steplimit" accesskey="p" rel="prev">sntp steplimit</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="ntpversion-option-_0028_002do_0029"></a>
|
|
<h4 class="subsection">1.1.12 ntpversion option (-o)</h4>
|
|
<a name="index-sntp_002dntpversion"></a>
|
|
|
|
<p>This is the “send <var>int</var> as our ntp protocol version” option.
|
|
This option takes a number argument.
|
|
When sending requests to a remote server, tell them we are running
|
|
NTP protocol version <samp>ntpversion</samp> .
|
|
</p><hr>
|
|
<a name="sntp-usereservedport"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-timeout" accesskey="n" rel="next">sntp timeout</a>, Previous: <a href="#sntp-ntpversion" accesskey="p" rel="prev">sntp ntpversion</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="usereservedport-option-_0028_002dr_0029"></a>
|
|
<h4 class="subsection">1.1.13 usereservedport option (-r)</h4>
|
|
<a name="index-sntp_002dusereservedport"></a>
|
|
|
|
<p>This is the “use the ntp reserved port (port 123)” option.
|
|
Use port 123, which is reserved for NTP, for our network
|
|
communications.
|
|
</p><hr>
|
|
<a name="sntp-timeout"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-wait" accesskey="n" rel="next">sntp wait</a>, Previous: <a href="#sntp-usereservedport" accesskey="p" rel="prev">sntp usereservedport</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="timeout-option-_0028_002dt_0029"></a>
|
|
<h4 class="subsection">1.1.14 timeout option (-t)</h4>
|
|
<a name="index-sntp_002dtimeout"></a>
|
|
|
|
<p>This is the “the number of seconds to wait for responses” option.
|
|
This option takes a number argument <samp>seconds</samp>.
|
|
When waiting for a reply, <code>sntp</code> will wait the number
|
|
of seconds specified before giving up. The default should be
|
|
more than enough for a unicast response. If <code>sntp</code> is
|
|
only waiting for a broadcast response a longer timeout is
|
|
likely needed.
|
|
</p><hr>
|
|
<a name="sntp-wait"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-config" accesskey="n" rel="next">sntp config</a>, Previous: <a href="#sntp-timeout" accesskey="p" rel="prev">sntp timeout</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="wait-option"></a>
|
|
<h4 class="subsection">1.1.15 wait option</h4>
|
|
<a name="index-sntp_002dwait"></a>
|
|
|
|
<p>This is the “wait for pending replies (if not setting the time)” option.
|
|
</p>
|
|
<p>This option has some usage constraints. It:
|
|
</p><ul>
|
|
<li> can be disabled with –no-wait.
|
|
</li><li> It is enabled by default.
|
|
</li></ul>
|
|
|
|
<p>If we are not setting the time, wait for all pending responses.
|
|
</p>
|
|
|
|
<hr>
|
|
<a name="sntp-config"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-exit-status" accesskey="n" rel="next">sntp exit status</a>, Previous: <a href="#sntp-wait" accesskey="p" rel="prev">sntp wait</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="presetting_002fconfiguring-sntp"></a>
|
|
<h4 class="subsection">1.1.16 presetting/configuring sntp</h4>
|
|
|
|
<p>Any option that is not marked as <i>not presettable</i> may be preset by
|
|
loading values from configuration ("rc" or "ini") files, and values from environment variables named <code>SNTP</code> and <code>SNTP_<OPTION_NAME></code>. <code><OPTION_NAME></code> must be one of
|
|
the options listed above in upper case and segmented with underscores.
|
|
The <code>SNTP</code> variable will be tokenized and parsed like
|
|
the command line. The remaining variables are tested for existence and their
|
|
values are treated like option arguments.
|
|
</p>
|
|
|
|
<p><code>libopts</code> will search in 2 places for configuration files:
|
|
</p><ul>
|
|
<li> $HOME
|
|
</li><li> $PWD
|
|
</li></ul>
|
|
<p>The environment variables <code>HOME</code>, and <code>PWD</code>
|
|
are expanded and replaced when <samp>sntp</samp> runs.
|
|
For any of these that are plain files, they are simply processed.
|
|
For any that are directories, then a file named <samp>.ntprc</samp> is searched for
|
|
within that directory and processed.
|
|
</p>
|
|
<p>Configuration files may be in a wide variety of formats.
|
|
The basic format is an option name followed by a value (argument) on the
|
|
same line. Values may be separated from the option name with a colon,
|
|
equal sign or simply white space. Values may be continued across multiple
|
|
lines by escaping the newline with a backslash.
|
|
</p>
|
|
<p>Multiple programs may also share the same initialization file.
|
|
Common options are collected at the top, followed by program specific
|
|
segments. The segments are separated by lines like:
|
|
</p><div class="example">
|
|
<pre class="example">[SNTP]
|
|
</pre></div>
|
|
<p>or by
|
|
</p><div class="example">
|
|
<pre class="example"><?program sntp>
|
|
</pre></div>
|
|
<p>Do not mix these styles within one configuration file.
|
|
</p>
|
|
<p>Compound values and carefully constructed string values may also be
|
|
specified using XML syntax:
|
|
</p><div class="example">
|
|
<pre class="example"><option-name>
|
|
<sub-opt>...&lt;...&gt;...</sub-opt>
|
|
</option-name>
|
|
</pre></div>
|
|
<p>yielding an <code>option-name.sub-opt</code> string value of
|
|
</p><div class="example">
|
|
<pre class="example">"...<...>..."
|
|
</pre></div>
|
|
<p><code>AutoOpts</code> does not track suboptions. You simply note that it is a
|
|
hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching
|
|
the associated name/value pair list (see: optionFindValue).
|
|
</p>
|
|
<p>The command line options relating to configuration and/or usage help are:
|
|
</p>
|
|
<a name="version-_0028_002d_0029"></a>
|
|
<h4 class="subsubheading">version (-)</h4>
|
|
|
|
<p>Print the program version to standard out, optionally with licensing
|
|
information, then exit 0. The optional argument specifies how much licensing
|
|
detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument.
|
|
Only the first letter of the argument is examined:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dt>‘<samp>version</samp>’</dt>
|
|
<dd><p>Only print the version. This is the default.
|
|
</p></dd>
|
|
<dt>‘<samp>copyright</samp>’</dt>
|
|
<dd><p>Name the copyright usage licensing terms.
|
|
</p></dd>
|
|
<dt>‘<samp>verbose</samp>’</dt>
|
|
<dd><p>Print the full copyright usage licensing terms.
|
|
</p></dd>
|
|
</dl>
|
|
|
|
<hr>
|
|
<a name="sntp-exit-status"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-Usage" accesskey="n" rel="next">sntp Usage</a>, Previous: <a href="#sntp-config" accesskey="p" rel="prev">sntp config</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="sntp-exit-status-1"></a>
|
|
<h4 class="subsection">1.1.17 sntp 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>
|
|
<dt>‘<samp>66 (EX_NOINPUT)</samp>’</dt>
|
|
<dd><p>A specified configuration file could not be loaded.
|
|
</p></dd>
|
|
<dt>‘<samp>70 (EX_SOFTWARE)</samp>’</dt>
|
|
<dd><p>libopts had an internal operational error. Please report
|
|
it to autogen-users@lists.sourceforge.net. Thank you.
|
|
</p></dd>
|
|
</dl>
|
|
<hr>
|
|
<a name="sntp-Usage"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="#sntp-Authors" accesskey="n" rel="next">sntp Authors</a>, Previous: <a href="#sntp-exit-status" accesskey="p" rel="prev">sntp exit status</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="sntp-Usage-1"></a>
|
|
<h4 class="subsection">1.1.18 sntp Usage</h4>
|
|
<hr>
|
|
<a name="sntp-Authors"></a>
|
|
<div class="header">
|
|
<p>
|
|
Previous: <a href="#sntp-Usage" accesskey="p" rel="prev">sntp Usage</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
|
|
</div>
|
|
<a name="sntp-Authors-1"></a>
|
|
<h4 class="subsection">1.1.19 sntp Authors</h4>
|
|
|
|
<hr>
|
|
<a name="Usage"></a>
|
|
<div class="header">
|
|
<p>
|
|
Previous: <a href="#sntp-Invocation" accesskey="p" rel="prev">sntp Invocation</a>, Up: <a href="#sntp-Description" accesskey="u" rel="up">sntp Description</a> </p>
|
|
</div>
|
|
<a name="Usage-1"></a>
|
|
<h3 class="section">1.2 Usage</h3>
|
|
|
|
<p>The simplest use of this program is as an unprivileged command to
|
|
check the current time, offset, and error in the local clock.
|
|
For example:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">sntp ntpserver.somewhere
|
|
</pre></div>
|
|
|
|
<p>With suitable privilege, it can be run as a command or in a
|
|
<code>crom</code> job to reset the local clock from a reliable server, like
|
|
the <code>ntpdate</code> and <code>rdate</code> commands.
|
|
For example:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">sntp -a ntpserver.somewhere
|
|
</pre></div>
|
|
<hr>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|