<?xml version='1.0'?> <!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-
-<!--
- This file is part of systemd.
-
- Copyright 2014 Kay Sievers
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
--->
+<!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="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
- <refentryinfo>
- <title>systemd-timesyncd.service</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Kay</firstname>
- <surname>Sievers</surname>
- <email>kay@vrfy.org</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>systemd-timesyncd.service</refentrytitle>
- <manvolnum>8</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>systemd-timesyncd.service</refname>
- <refname>systemd-timesyncd</refname>
- <refpurpose>Network Time Synchronization</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename>systemd-timesyncd.service</filename></para>
- <para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para><filename>systemd-timesyncd</filename> is a
- system service that may be used to synchronize the
- local system clock with a remote Network Time Protocol
- server. It also saves the local time to disk every
- time the clock has been synchronized and uses this to
- possibly advance the system realtime clock on
- subsequent reboots to ensure it
- monotonically advances even if the system lacks a
- battery-buffered RTC chip.</para>
-
- <para>The NTP servers contacted are determined from
- the global settings in
- <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- the per-link static settings in
- <filename>.network</filename> files, and the per-link
- dynamic settings received over DHCP. See
- <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for more details.</para>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</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>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>systemd-timesyncd.service</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-timesyncd.service</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-timesyncd.service</refname>
+ <refname>systemd-timesyncd</refname>
+ <refpurpose>Network Time Synchronization</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>systemd-timesyncd.service</filename></para>
+ <para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-timesyncd</filename> is a system service
+ that may be used to synchronize the local system clock with a
+ remote Network Time Protocol server. It also saves the local time
+ to disk every time the clock has been synchronized and uses this
+ to possibly advance the system realtime clock on subsequent
+ reboots to ensure it monotonically advances even if the system
+ lacks a battery-buffered RTC chip.</para>
+
+ <para>The <filename>systemd-timesyncd</filename> service
+ specifically implements only SNTP. This minimalistic
+ service will set the system clock for large offsets or
+ slowly adjust it for smaller deltas. More complex use
+ cases are not covered by <filename>systemd-timesyncd</filename>.</para>
+
+ <para>The NTP servers contacted are determined from the global
+ settings in
+ <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ the per-link static settings in <filename>.network</filename>
+ files, and the per-link dynamic settings received over DHCP. See
+ <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more details.</para>
+
+ <para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>set-ntp</command> command may be used to enable and
+ start, or disable and stop this service.</para>
+
+ <para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>timesync-status</command> or <command>show-timesync</command> command can be used to show the
+ current status of this service.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Files</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>/var/lib/systemd/timesync/clock</filename></term>
+
+ <listitem>
+ <para>The modification time of this file indicates the timestamp of the last successful
+ synchronization (or at least the systemd build date, in case synchronization was not
+ possible).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>/run/systemd/timesync/synchronized</filename></term>
+
+ <listitem>
+ <para>A file that is touched on each successful synchronization, to assist
+ <filename>systemd-time-wait-sync</filename> and other applications to detecting synchronization
+ events.</para>
+ </listitem>
+
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-time-wait-sync.service</refentrytitle><manvolnum>8</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>
+ </para>
+ </refsect1>
</refentry>
projects / thirdparty / systemd.git / blobdiff