1<?xml version='1.0'?> <!--*-nxml-*-->
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="systemd-timedated.service" conditional='ENABLE_TIMEDATED'>
7
8  <refentryinfo>
9    <title>systemd-timedated.service</title>
10    <productname>systemd</productname>
11  </refentryinfo>
12
13  <refmeta>
14    <refentrytitle>systemd-timedated.service</refentrytitle>
15    <manvolnum>8</manvolnum>
16  </refmeta>
17
18  <refnamediv>
19    <refname>systemd-timedated.service</refname>
20    <refname>systemd-timedated</refname>
21    <refpurpose>Time and date bus mechanism</refpurpose>
22  </refnamediv>
23
24  <refsynopsisdiv>
25    <para><filename>systemd-timedated.service</filename></para>
26    <para><filename>/usr/lib/systemd/systemd-timedated</filename></para>
27  </refsynopsisdiv>
28
29  <refsect1>
30    <title>Description</title>
31
32    <para><filename>systemd-timedated.service</filename> is a system service
33    that may be used as a mechanism to change the system clock and
34    timezone, as well as to enable/disable network time synchronization.
35    <filename>systemd-timedated</filename> is automatically activated
36    on request and terminates itself when it is unused.</para>
37
38    <para>The tool
39    <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
40    is a command line client to this service.</para>
41
42    <para><filename>systemd-timedated</filename> currently offers access to
43    the following four settings:
44    <itemizedlist>
45      <listitem><para>The system time</para></listitem>
46
47      <listitem><para>The system timezone</para></listitem>
48
49      <listitem><para>A boolean controlling whether the system RTC is in local or UTC
50      timezone</para></listitem>
51
52      <listitem><para>Whether the time synchronization service is enabled/started or
53      disabled/stopped, see next section.</para></listitem>
54    </itemizedlist></para>
55
56    <para>See
57    <citerefentry><refentrytitle>org.freedesktop.timedate1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
58    and
59    <citerefentry><refentrytitle>org.freedesktop.LogControl1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
60    for information about the D-Bus API.</para>
61  </refsect1>
62
63  <refsect1>
64    <title>List of network time synchronization services</title>
65
66    <para><command>systemd-timesyncd</command> will look for files with a <literal>.list</literal> extension
67    in <filename>ntp-units.d/</filename> directories. Each file is parsed as a list of unit names, one per
68    line. Empty lines and lines with comments (<literal>#</literal>) are ignored.  Files are read from
69    <filename>/usr/lib/systemd/ntp-units.d/</filename> and the corresponding directories under
70    <filename>/etc/</filename>, <filename>/run/</filename>, <filename>/usr/local/lib/</filename>. Files in
71    <filename>/etc/</filename> override files with the same name in <filename>/run/</filename>,
72    <filename>/usr/local/lib/</filename>, and <filename>/usr/lib/</filename>. Files in
73    <filename>/run/</filename> override files with the same name under <filename>/usr/</filename>. Packages
74    should install their configuration files in <filename>/usr/lib/</filename> (distribution packages) or
75    <filename>/usr/local/lib/</filename> (local installs).</para>
76
77    <example>
78      <title><filename>ntp-units.d/</filename> entry for <command>systemd-timesyncd</command></title>
79      <programlisting># /usr/lib/systemd/ntp-units.d/80-systemd-timesync.list
80systemd-timesyncd.service
81</programlisting>
82    </example>
83
84    <para>If the environment variable <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname> is set,
85    <command>systemd-timesyncd</command> will parse the contents of that variable as a colon-separated list
86    of unit names. When set, this variable overrides the file-based list described above.</para>
87
88    <example>
89      <title>An override that specifies that <command>chronyd</command> should be used if available</title>
90      <programlisting>SYSTEMD_TIMEDATED_NTP_SERVICES=chronyd.service:systemd-timesyncd.service</programlisting>
91    </example>
92  </refsect1>
93
94  <refsect1>
95    <title>See Also</title>
96    <para>
97      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
98      <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
99      <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
100      <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
101      <citerefentry><refentrytitle>systemd-timesyncd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
102    </para>
103  </refsect1>
104
105</refentry>
106