man/systemd-timedated.service.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   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     for information about the D-Bus API.</para>
  59   </refsect1>
  60
  61   <refsect1>
  62     <title>List of network time synchronization services</title>
  63
  64     <para><command>systemd-timesyncd</command> will look for files with a <literal>.list</literal> extension
  65     in <filename>ntp-units.d/</filename> directories. Each file is parsed as a list of unit names, one per
  66     line. Empty lines and lines with comments (<literal>#</literal>) are ignored.  Files are read from
  67     <filename>/usr/lib/systemd/ntp-units.d/</filename> and the corresponding directories under
  68     <filename>/etc/</filename>, <filename>/run/</filename>, <filename>/usr/local/lib/</filename>. Files in
  69     <filename>/etc/</filename> override files with the same name in <filename>/run/</filename>,
  70     <filename>/usr/local/lib/</filename>, and <filename>/usr/lib/</filename>. Files in
  71     <filename>/run/</filename> override files with the same name under <filename>/usr/</filename>. Packages
  72     should install their configuration files in <filename>/usr/lib/</filename> (distribution packages) or
  73     <filename>/usr/local/lib/</filename> (local installs).</para>
  74
  75     <example>
  76       <title><filename>ntp-units.d/</filename> entry for <command>systemd-timesyncd</command></title>
  77       <programlisting># /usr/lib/systemd/ntp-units.d/80-systemd-timesync.list
  78 systemd-timesyncd.service
  79 </programlisting>
  80     </example>
  81
  82     <para>If the environment variable <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname> is set,
  83     <command>systemd-timesyncd</command> will parse the contents of that variable as a colon-separated list
  84     of unit names. When set, this variable overrides the file-based list described above.</para>
  85
  86     <example>
  87       <title>An override that specifies that <command>chronyd</command> should be used if available</title>
  88       <programlisting>SYSTEMD_TIMEDATED_NTP_SERVICES=chronyd.service:systemd-timesyncd.service</programlisting>
  89     </example>
  90   </refsect1>
  91
  92   <refsect1>
  93     <title>See Also</title>
  94     <para>
  95       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  96       <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  97       <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  98       <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  99       <citerefentry><refentrytitle>systemd-timesyncd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 100     </para>
 101   </refsect1>
 102
 103 </refentry>