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systemd/man/systemd-timesyncd.service.xml

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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Copyright 2014 Kay Sievers
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<refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
<refentryinfo>
<title>systemd-timesyncd.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Kay</firstname>
<surname>Sievers</surname>
<email>kay@vrfy.org</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-timesyncd.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-timesyncd.service</refname>
<refname>systemd-timesyncd</refname>
<refpurpose>Network Time Synchronization</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-timesyncd.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-timesyncd</filename> is a system service
that may be used to synchronize the local system clock with a
remote Network Time Protocol server. It also saves the local time
to disk every time the clock has been synchronized and uses this
to possibly advance the system realtime clock on subsequent
reboots to ensure it monotonically advances even if the system
lacks a battery-buffered RTC chip.</para>
<para>The NTP servers contacted are determined from the global
settings in
<citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
the per-link static settings in <filename>.network</filename>
files, and the per-link dynamic settings received over DHCP. See
<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more details.</para>
<para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>set-ntp</command> command may be used to enable and
start, or disable and stop this service.</para>
</refsect1>
<refsect1>
<title>Files</title>
<variablelist>
<varlistentry>
<term><filename>/var/lib/systemd/clock</filename></term>
<listitem>
<para>This file contains the timestamp of the last successful
synchronization.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>