Systemd/man/org.freedesktop.timedate1.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" >
<!-- SPDX-License-Identifier: LGPL-2.1+ -->

<refentry id="org.freedesktop.timedate1" conditional='ENABLE_TIMEDATED'
    xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>org.freedesktop.timedate1</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>org.freedesktop.timedate1</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>org.freedesktop.timedate1</refname>
    <refpurpose>The D-Bus interface of systemd-timedated</refpurpose>
  </refnamediv>

  <refsect1>
    <title>Introduction</title>

    <para>
    <citerefentry><refentrytitle>systemd-timedated.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    is a system service that can be used to control the system time and related settings.  This page
    describes the D-Bus interface.</para>
  </refsect1>

  <refsect1>
    <title>The D-Bus API</title>

    <para>The service exposes the following interfaces on the bus:</para>

    <programlisting>
$ gdbus introspect --system \
        --dest org.freedesktop.timedate1 \
        --object-path /org/freedesktop/timedate1

node /org/freedesktop/timedate1 {
  interface org.freedesktop.timedate1 {
    methods:
      SetTime(in  x usec_utc,
              in  b relative,
              in  b user_interaction);
      SetTimezone(in  s timezone,
                  in  b user_interaction);
      SetLocalRTC(in  b local_rtc,
                  in  b fix_system,
                  in  b user_interaction);
      SetNTP(in  b use_ntp,
             in  b user_interaction);
    signals:
    properties:
      readonly s Timezone = 'Europe/Berlin';
      readonly b LocalRTC = false;
      readonly b NTP = true;
  };
  interface org.freedesktop.DBus.Properties {
  };
  interface org.freedesktop.DBus.Introspectable {
  };
  interface org.freedesktop.DBus.Peer {
  };
};
    </programlisting>

    <refsect2>
      <title>Methods</title>

      <para>Use <function>SetTime()</function> to change the system clock. Pass a value of microseconds since
      the UNIX epoch (1 Jan 1970 UTC). If <varname>relative</varname> is true, the passed usec value will be
      added to the current system time, if it is false the current system time will be set to the passed usec
      value. If the system time is set with this call the RTC will be updated as well.</para>

      <para>Use <function>SetTimezone()</function> to set the system timezone. Pass a value like
      <literal>Europe/Berlin</literal> to set the timezone. Valid timezones are listed in
      <filename>/usr/share/zoneinfo/zone.tab</filename>. If the RTC is configured to be maintained in local
      time, it will be updated accordingly.</para>

      <para>Use <function>SetLocalRTC()</function> to control whether the RTC is in local time or UTC. It is
      strongly recommended to maintain the RTC in UTC. Some OSes (Windows) however maintain the RTC in local
      time, which might make it necessary to enable this feature. However, this creates various problems as
      daylight changes might be missed. If <varname>fix_system</varname> is passed <literal>true</literal>,
      the time from the RTC is read again and the system clock adjusted according to the new setting. If
      <varname>fix_system</varname> is passed <literal>false</literal> the system time is written to the RTC
      taking the new setting into account. Use <varname>fix_system=true</varname> in installers and livecds
      where the RTC is probably more reliable than the system time. Use <varname>fix_system=false</varname>
      in configuration UIs that are run during normal operation and where the system clock is probably more
      reliable than the RTC.</para>

      <para>Use <function>SetNTP()</function> to control whether the system clock is synchronized with the
      network using <filename>systemd-timesyncd</filename>. This will enable and start or disable and stop
      the chosen time synchronization service.</para>

      <para>Whenever the timezone and local_rtc settings are changed via the daemon
      <function>PropertyChanged</function> signals are sent out to which clients can subscribe. Changing the
      time settings using this interface is authenticated via PolicyKit.</para>

      <para>Note that this service will not inform you about system time changes. Use
      <citerefentry project='man-pages'><refentrytitle>timerfd</refentrytitle><manvolnum>3</manvolnum></citerefentry>
      with <constant>CLOCK_REALTIME</constant> and <constant>TFD_TIMER_CANCEL_ON_SET</constant> for that.
      </para>

      <para>The <varname>user_interaction</varname> boolean parameters can be used to control whether
      PolicyKit should interactively ask the user for authentication credentials if it needs to.</para>

      <para>The PolicyKit action for <function>SetTimezone()</function> is
      <interfacename>org.freedesktop.timedate1.set-timezone</interfacename>. For
      <function>SetLocalRTC()</function> it is
      <interfacename>org.freedesktop.timedate1.set-local-rtc</interfacename>, for
      <function>SetTime()</function> it is <interfacename>org.freedesktop.timedate1.set-time</interfacename>
      and for <function>SetNTP()</function> it is
      <interfacename>org.freedesktop.timedate1.set-ntp</interfacename>.</para>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>Versioning</title>

    <para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
    the usual interface versioning guidelines</ulink>.</para>
  </refsect1>

  <refsect1>
    <title>See also</title>

      <para><ulink url="https://lists.freedesktop.org/archives/systemd-devel/2011-May/002526.html">More information on how the system clock and RTC interact</ulink></para>
  </refsect1>
</refentry>