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systemd/man/systemd-timedated.service.xml
2020-11-09 13:23:58 +09:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!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-or-later -->
<refentry id="systemd-timedated.service" conditional='ENABLE_TIMEDATED'>
<refentryinfo>
<title>systemd-timedated.service</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-timedated.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-timedated.service</refname>
<refname>systemd-timedated</refname>
<refpurpose>Time and date bus mechanism</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-timedated.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-timedated</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-timedated.service</filename> is a system service
that may be used as a mechanism to change the system clock and
timezone, as well as to enable/disable network time synchronization.
<filename>systemd-timedated</filename> is automatically activated
on request and terminates itself when it is unused.</para>
<para>The tool
<citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
is a command line client to this service.</para>
<para><filename>systemd-timedated</filename> currently offers access to
the following four settings:
<itemizedlist>
<listitem><para>The system time</para></listitem>
<listitem><para>The system timezone</para></listitem>
<listitem><para>A boolean controlling whether the system RTC is in local or UTC
timezone</para></listitem>
<listitem><para>Whether the time synchronization service is enabled/started or
disabled/stopped, see next section.</para></listitem>
</itemizedlist></para>
<para>See
<citerefentry><refentrytitle>org.freedesktop.timedate1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>org.freedesktop.LogControl1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for information about the D-Bus API.</para>
</refsect1>
<refsect1>
<title>List of network time synchronization services</title>
<para><command>systemd-timesyncd</command> will look for files with a <literal>.list</literal> extension
in <filename>ntp-units.d/</filename> directories. Each file is parsed as a list of unit names, one per
line. Empty lines and lines with comments (<literal>#</literal>) are ignored. Files are read from
<filename>/usr/lib/systemd/ntp-units.d/</filename> and the corresponding directories under
<filename>/etc/</filename>, <filename>/run/</filename>, <filename>/usr/local/lib/</filename>. Files in
<filename>/etc/</filename> override files with the same name in <filename>/run/</filename>,
<filename>/usr/local/lib/</filename>, and <filename>/usr/lib/</filename>. Files in
<filename>/run/</filename> override files with the same name under <filename>/usr/</filename>. Packages
should install their configuration files in <filename>/usr/lib/</filename> (distribution packages) or
<filename>/usr/local/lib/</filename> (local installs).</para>
<example>
<title><filename>ntp-units.d/</filename> entry for <command>systemd-timesyncd</command></title>
<programlisting># /usr/lib/systemd/ntp-units.d/80-systemd-timesync.list
systemd-timesyncd.service
</programlisting>
</example>
<para>If the environment variable <varname>$SYSTEMD_TIMEDATED_NTP_SERVICES</varname> is set,
<command>systemd-timesyncd</command> will parse the contents of that variable as a colon-separated list
of unit names. When set, this variable overrides the file-based list described above.</para>
<example>
<title>An override that specifies that <command>chronyd</command> should be used if available</title>
<programlisting>SYSTEMD_TIMEDATED_NTP_SERVICES=chronyd.service:systemd-timesyncd.service</programlisting>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</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>,
<citerefentry><refentrytitle>systemd-timesyncd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>