Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 127 insertions, 0 deletions

diff --git a/man/systemd-timesyncd.service.xml b/man/systemd-timesyncd.service.xml
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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-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
+
+  <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 (NTP) 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 (roughly) monotonically advances even if the system lacks a
+    battery-buffered RTC chip.</para>
+
+    <para>The <filename>systemd-timesyncd</filename> service implements SNTP only. This minimalistic service
+    will step the system clock for large offsets or slowly adjust it for smaller deltas. Complex use cases
+    that require full NTP support (and where SNTP is not sufficient) 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
+    further 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>
+
+    <para><filename>systemd-timesyncd</filename> initialization delays the start of units that are ordered
+    after <filename>time-set.target</filename> (see
+    <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+    details) until the local time has been updated from <filename>/var/lib/systemd/timesync/clock</filename>
+    (see below) in order to make it roughly monotonic. It does not delay other units until synchronization
+    with an accurate reference time sources has been reached. Use
+    <citerefentry><refentrytitle>systemd-time-wait-sync.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    to achieve that, which will delay start of units that are ordered after
+    <filename>time-sync.target</filename> until synchronization to an accurate reference clock is
+    reached.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Files</title>
+
+    <variablelist>
+      <varlistentry>
+        <term><filename>/var/lib/systemd/timesync/clock</filename></term>
+
+        <listitem>
+          <para>The modification time ("mtime") of this file is updated on each successful NTP
+          synchronization or after each <varname>SaveIntervalSec=</varname> time interval, as specified in
+          <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+          <para>When initializing, the local clock is advanced to the modification time of this file (if the
+          file timestamp is in the past this adjustment is not made). If the file does not exist yet, the
+          clock is instead advanced to the modification time of <filename>/usr/lib/clock-epoch</filename> –
+          if it exists – or to a time derived from the source tree at build time. This mechanism is used to
+          ensure that the system clock remains somewhat reasonably initialized and roughly monotonic across
+          reboots, in case no battery-buffered local RTC is available.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/usr/lib/clock-epoch</filename></term>
+
+        <listitem><para>The modification time ("mtime") of this file is used for advancing the system clock
+        in case <filename>/var/lib/systemd/timesync/clock</filename> does not exist yet, see
+        above.</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
+          with accurate reference clocks.</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>systemd.special</refentrytitle><manvolnum>7</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>