test-hostname-util: add assert_se's to make coverity happy

[thirdparty/systemd.git] / man / timedatectl.xml

<?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">

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<refentry id="timedatectl" conditional='ENABLE_TIMEDATED'
  xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>timedatectl</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>timedatectl</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>timedatectl</refname>
    <refpurpose>Control the system time and date</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>timedatectl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>timedatectl</command> may be used to query and
    change the system clock and its settings.</para>

    <para>Use
    <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    to initialize the system time zone for mounted (but not booted)
    system images.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>

    <variablelist>
      <varlistentry>
        <term><option>--no-ask-password</option></term>

        <listitem><para>Do not query the user for authentication for
        privileged operations.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--adjust-system-clock</option></term>

        <listitem><para>If <command>set-local-rtc</command> is invoked
        and this option is passed, the system clock is synchronized
        from the RTC again, taking the new setting into account.
        Otherwise, the RTC is synchronized from the system
        clock.</para></listitem>
      </varlistentry>

      <xi:include href="user-system-options.xml" xpointer="host" />
      <xi:include href="user-system-options.xml" xpointer="machine" />

      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
      <xi:include href="standard-options.xml" xpointer="no-pager" />
    </variablelist>

    <para>The following commands are understood:</para>

    <variablelist>
      <varlistentry>
        <term><command>status</command></term>

        <listitem><para>Show current settings of the system clock and RTC,
        including whether network time synchronization through
        <filename>systemd-timesyncd.service</filename> is active. Even if it is
        inactive, a different service might still synchronize the clock.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>set-time [TIME]</command></term>

        <listitem><para>Set the system clock to the specified time.
        This will also update the RTC time accordingly. The time may
        be specified in the format "2012-10-30
        18:17:16".</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>set-timezone [TIMEZONE]</command></term>

        <listitem><para>Set the system time zone to the specified
        value. Available timezones can be listed with
        <command>list-timezones</command>. If the RTC is configured to
        be in the local time, this will also update the RTC time. This
        call will alter the <filename>/etc/localtime</filename>
        symlink. See
        <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for more information.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>list-timezones</command></term>

        <listitem><para>List available time zones, one per line.
        Entries from the list can be set as the system timezone with
        <command>set-timezone</command>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>set-local-rtc [BOOL]</command></term>

        <listitem><para>Takes a boolean argument. If
        <literal>0</literal>, the system is configured to maintain the
        RTC in universal time. If <literal>1</literal>, it will
        maintain the RTC in local time instead. Note that maintaining
        the RTC in the local timezone is not fully supported and will
        create various problems with time zone changes and daylight
        saving adjustments. If at all possible, keep the RTC in UTC
        mode. Note that invoking this will also synchronize the RTC
        from the system clock, unless
        <option>--adjust-system-clock</option> is passed (see above).
        This command will change the 3rd line of
        <filename>/etc/adjtime</filename>, as documented in
        <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>set-ntp [BOOL]</command></term>

        <listitem><para>Takes a boolean argument. Controls whether
        network time synchronization is active and enabled (if
        available). This enables and starts, or disables and stops the
        <filename>systemd-timesyncd.service</filename> unit. It does
        not affect the state of any other, unrelated network time
        synchronization services that might be installed on the
        system. This command is hence mostly equivalent to:
        <command>systemctl enable --now
        systemd-timesyncd.service</command> and <command>systemctl
        disable --now systemd-timesyncd.service</command>, but is
        protected by a different access policy.</para>

        <para>Note that even if time synchronization is turned off
        with this command, another unrelated system service might
        still synchronize the clock with the network. Also note that,
        strictly speaking,
        <filename>systemd-timesyncd.service</filename> does more than
        just network time synchronization, as it ensures a monotonic
        clock on systems without RTC even if no network is
        available. See
        <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        for details about this.</para></listitem>
      </varlistentry>

    </variablelist>

  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure
    code otherwise.</para>
  </refsect1>

  <xi:include href="less-variables.xml" />

  <refsect1>
    <title>Examples</title>
    <para>Show current settings:
    <programlisting>$ timedatectl
                      Local time: Thu 2017-09-21 16:08:56 CEST
                  Universal time: Thu 2017-09-21 14:08:56 UTC
                        RTC time: Thu 2017-09-21 14:08:56
                       Time zone: Europe/Warsaw (CEST, +0200)
       System clock synchronized: yes
systemd-timesyncd.service active: yes
                 RTC in local TZ: no</programlisting>
    </para>

    <para>Enable network time synchronization:
    <programlisting>$ timedatectl set-ntp true
==== AUTHENTICATING FOR org.freedesktop.timedate1.set-ntp ===
Authentication is required to control whether network time synchronization shall be enabled.
Authenticating as: user
Password: ********
==== AUTHENTICATION COMPLETE ===</programlisting>

    <programlisting>$ systemctl status systemd-timesyncd.service
● systemd-timesyncd.service - Network Time Synchronization
   Loaded: loaded (/usr/lib/systemd/system/systemd-timesyncd.service; enabled)
   Active: active (running) since Mo 2015-03-30 14:20:38 CEST; 5s ago
     Docs: man:systemd-timesyncd.service(8)
 Main PID: 595 (systemd-timesyn)
   Status: "Using Time Server 216.239.38.15:123 (time4.google.com)."
   CGroup: /system.slice/systemd-timesyncd.service
           └─595 /usr/lib/systemd/systemd-timesyncd
…</programlisting>
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>date</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-timedated.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>