systemd/man/systemd-timesyncd.service.xml

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<!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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<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>
        </refsect1>

        <refsect1>
                <title>Files</title>

                <variablelist>
                        <varlistentry>
                                <term><filename>/var/lib/systemd/clock</filename></term>

                                <listitem>
                                        <para>This file contains the timestamp of 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>