man: fix link markup

[thirdparty/systemd.git] / man / org.freedesktop.timedate1.xml

<?xml version='1.0'?>
<!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 executable="systemd-timedated" node="/org/freedesktop/timedate1" interface="org.freedesktop.timedate1">
node /org/freedesktop/timedate1 {
  interface org.freedesktop.timedate1 {
    methods:
      SetTime(in  x usec_utc,
              in  b relative,
              in  b interactive);
      SetTimezone(in  s timezone,
                  in  b interactive);
      SetLocalRTC(in  b local_rtc,
                  in  b fix_system,
                  in  b interactive);
      SetNTP(in  b use_ntp,
             in  b interactive);
      ListTimezones(out as timezones);
    properties:
      readonly s Timezone = '...';
      readonly b LocalRTC = ...;
      @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
      readonly b CanNTP = ...;
      readonly b NTP = ...;
      @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
      readonly b NTPSynchronized = ...;
      @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
      readonly t TimeUSec = ...;
      @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
      readonly t RTCTimeUSec = ...;
  };
  interface org.freedesktop.DBus.Peer { ... };
  interface org.freedesktop.DBus.Introspectable { ... };
  interface org.freedesktop.DBus.Properties { ... };
};
    </programlisting>

    <!--Autogenerated cross-references for systemd.directives, do not edit-->

    <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.timedate1"/>

    <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.timedate1"/>

    <variablelist class="dbus-method" generated="True" extra-ref="SetTime()"/>

    <variablelist class="dbus-method" generated="True" extra-ref="SetTimezone()"/>

    <variablelist class="dbus-method" generated="True" extra-ref="SetLocalRTC()"/>

    <variablelist class="dbus-method" generated="True" extra-ref="SetNTP()"/>

    <variablelist class="dbus-method" generated="True" extra-ref="ListTimezones()"/>

    <variablelist class="dbus-property" generated="True" extra-ref="Timezone"/>

    <variablelist class="dbus-property" generated="True" extra-ref="LocalRTC"/>

    <variablelist class="dbus-property" generated="True" extra-ref="CanNTP"/>

    <variablelist class="dbus-property" generated="True" extra-ref="NTP"/>

    <variablelist class="dbus-property" generated="True" extra-ref="NTPSynchronized"/>

    <variablelist class="dbus-property" generated="True" extra-ref="TimeUSec"/>

    <variablelist class="dbus-property" generated="True" extra-ref="RTCTimeUSec"/>

    <!--End of Autogenerated section-->

    <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 method, 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. However, some OSes (Windows) maintain the RTC in local
      time, which might make it necessary to enable this feature. Note that this might create various problems as
      daylight changes could be missed. If <varname>fix_system</varname> is <literal>true</literal>,
      the time from the RTC is read again and the system clock is adjusted according to the new setting. If
      <varname>fix_system</varname> is <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><function>ListTimezones()</function> returns a list of time zones known on the local system as an
      array of names (<literal>["Africa/Abidjan", "Africa/Accra", ..., "UTC"]</literal>).</para>
    </refsect2>

    <refsect2>
      <title>Properties</title>

      <para><varname>Timezone</varname> shows the currently configured time zone.
      <varname>LocalRTC</varname> shows whether the RTC is configured to use UTC (false), or the local time
      zone (true). <varname>CanNTP</varname> shows whether a service to perform time synchronization over the
      network is available, and <varname>NTP</varname> shows whether such a service is enabled.</para>

      <para><varname>NTPSynchronized</varname> shows whether the kernel reports the time as synchronized
      (c.f.
      <citerefentry project="man-pages"><refentrytitle>adjtimex</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
      <varname>TimeUSec</varname> and <varname>RTCTimeUSec</varname> show the current time on the system and
      in the RTC. The purpose of those three properties is to allow remote clients to access this information
      over D-Bus. Local clients can access the information directly.</para>

      <para>Whenever the <varname>Timezone</varname> and <varname>LocalRTC</varname> settings are changed via
      the daemon, <function>PropertyChanged</function> signals are sent out to which clients can subscribe.
      </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>
    </refsect2>

    <refsect2>
      <title>Security</title>

      <para>The <varname>interactive</varname> boolean parameters can be used to control whether
      <ulink url="https://www.freedesktop.org/software/polkit/docs/latest/">polkit</ulink>
      should interactively ask the user for authentication credentials if required.</para>

      <para>The polkit 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>.
      <function>ListTimezones()</function> does not require any privileges.
      </para>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <example>
      <title>Introspect <interfacename>org.freedesktop.timedate1</interfacename> on the bus</title>

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