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1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4
5 <!--
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8   Copyright 2014 Kay Sievers
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23
24 <refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
25
26   <refentryinfo>
27     <title>systemd-timesyncd.service</title>
28     <productname>systemd</productname>
29
30     <authorgroup>
31       <author>
32         <contrib>Developer</contrib>
33         <firstname>Kay</firstname>
34         <surname>Sievers</surname>
35         <email>kay@vrfy.org</email>
36       </author>
37     </authorgroup>
38   </refentryinfo>
39
40   <refmeta>
41     <refentrytitle>systemd-timesyncd.service</refentrytitle>
42     <manvolnum>8</manvolnum>
43   </refmeta>
44
45   <refnamediv>
46     <refname>systemd-timesyncd.service</refname>
47     <refname>systemd-timesyncd</refname>
48     <refpurpose>Network Time Synchronization</refpurpose>
49   </refnamediv>
50
51   <refsynopsisdiv>
52     <para><filename>systemd-timesyncd.service</filename></para>
53     <para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
54   </refsynopsisdiv>
55
56   <refsect1>
57     <title>Description</title>
58
59     <para><filename>systemd-timesyncd</filename> is a system service
60     that may be used to synchronize the local system clock with a
61     remote Network Time Protocol server. It also saves the local time
62     to disk every time the clock has been synchronized and uses this
63     to possibly advance the system realtime clock on subsequent
64     reboots to ensure it monotonically advances even if the system
65     lacks a battery-buffered RTC chip.</para>
66
67     <para>The NTP servers contacted are determined from the global
68     settings in
69     <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
70     the per-link static settings in <filename>.network</filename>
71     files, and the per-link dynamic settings received over DHCP. See
72     <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
73     for more details.</para>
74   </refsect1>
75
76   <refsect1>
77     <title>Files</title>
78
79     <variablelist>
80       <varlistentry>
81         <term><filename>/var/lib/systemd/clock</filename></term>
82
83         <listitem>
84           <para>This file contains the timestamp of last successful
85           synchronization.</para>
86         </listitem>
87       </varlistentry>
88     </variablelist>
89   </refsect1>
90
91   <refsect1>
92     <title>See Also</title>
93     <para>
94       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
95       <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
96       <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
97       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</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     </para>
102   </refsect1>
103
104 </refentry>