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>