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This part of the copyright blurb stems from the GPL use recommendations: https://www.gnu.org/licenses/gpl-howto.en.html The concept appears to originate in times where version control was per file, instead of per tree, and was a way to glue the files together. Ultimately, we nowadays don't live in that world anymore, and this information is entirely useless anyway, as people are very welcome to copy these files into any projects they like, and they shouldn't have to change bits that are part of our copyright header for that. hence, let's just get rid of this old cruft, and shorten our codebase a bit.
119 lines
4.6 KiB
XML
119 lines
4.6 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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SPDX-License-Identifier: LGPL-2.1+
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Copyright 2014 Kay Sievers
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-->
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<refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
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<refentryinfo>
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<title>systemd-timesyncd.service</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Kay</firstname>
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<surname>Sievers</surname>
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<email>kay@vrfy.org</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-timesyncd.service</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-timesyncd.service</refname>
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<refname>systemd-timesyncd</refname>
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<refpurpose>Network Time Synchronization</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd-timesyncd.service</filename></para>
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<para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-timesyncd</filename> is a system service
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that may be used to synchronize the local system clock with a
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remote Network Time Protocol server. It also saves the local time
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to disk every time the clock has been synchronized and uses this
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to possibly advance the system realtime clock on subsequent
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reboots to ensure it monotonically advances even if the system
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lacks a battery-buffered RTC chip.</para>
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<para>The <filename>systemd-timesyncd</filename> service
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specifically implements only SNTP. This minimalistic
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service will set the system clock for large offsets or
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slowly adjust it for smaller deltas. More complex use
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cases are not covered by <filename>systemd-timesyncd</filename>.</para>
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<para>The NTP servers contacted are determined from the global
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settings in
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<citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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the per-link static settings in <filename>.network</filename>
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files, and the per-link dynamic settings received over DHCP. See
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<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more details.</para>
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<para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>set-ntp</command> command may be used to enable and
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start, or disable and stop this service.</para>
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<para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>timesync-status</command> or <command>show-timesync</command> command can be used to show the
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current status of this service.</para>
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</refsect1>
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<refsect1>
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<title>Files</title>
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<variablelist>
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<varlistentry>
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<term><filename>/var/lib/systemd/timesync/clock</filename></term>
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<listitem>
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<para>The modification time of this file indicates the timestamp of the last successful
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synchronization (or at least the systemd build date, in case synchronization was not
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possible).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/run/systemd/timesync/synchronized</filename></term>
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<listitem>
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<para>A file that is touched on each successful synchronization, to assist
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<filename>systemd-time-wait-sync</filename> and other applications to detecting synchronization
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events.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-time-wait-sync.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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