Systemd/man/systemd-timesyncd.service.xml

<?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">

<!--
  This file is part of systemd.

  Copyright 2014 Kay Sievers

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<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>