systemd/man/timedatectl.xml

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        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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<refentry id="timedatectl" conditional='ENABLE_TIMEDATED'>

        <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>
        </refsect1>

        <refsect1>
                <title>Options</title>

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

                <variablelist>
                        <varlistentry>
                                <term><option>-h</option></term>
                                <term><option>--help</option></term>

                                <listitem><para>Prints a short help
                                text and exits.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--version</option></term>

                                <listitem><para>Prints a short version
                                string and exits.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--no-pager</option></term>

                                <listitem><para>Do not pipe output into a
                                pager.</para></listitem>
                        </varlistentry>

                        <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>-P</option></term>
                                <term><option>--privileged</option></term>

                                <listitem><para>Acquire privileges via PolicyKit
                                before executing the operation.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-H</option></term>
                                <term><option>--host</option></term>

                                <listitem><para>Execute the operation
                                remotely. Specify a hostname, or
                                username and hostname separated by <literal>@</literal>,
                                to connect to. This will use SSH to
                                talk to a remote
                                system.</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>
                </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.</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><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 NTP based
                                network time synchronization is
                                enabled (if
                                available).</para></listitem>
                        </varlistentry>

                </variablelist>

        </refsect1>

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

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

        <refsect1>
                <title>Environment</title>

                <variablelist class='environment-variables'>
                        <varlistentry>
                                <term><varname>$SYSTEMD_PAGER</varname></term>
                                <listitem><para>Pager to use when
                                <option>--no-pager</option> is not given;
                                overrides <varname>$PAGER</varname>.  Setting
                                this to an empty string or the value
                                <literal>cat</literal> is equivalent to passing
                                <option>--no-pager</option>.</para></listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Examples</title>
                <para>Show current settings:
                <programlisting>
$ timedatectl
      Local time: Fri, 2012-11-02 09:26:46 CET
  Universal time: Fri, 2012-11-02 08:26:46 UTC
        RTC time: Fri, 2012-11-02 08:26:45
        Timezone: Europe/Warsaw
      UTC offset: +0100
     NTP enabled: no
NTP synchronized: no
 RTC in local TZ: no
      DST active: no
 Last DST change: CEST → CET, DST became inactive
                  Sun, 2012-10-28 02:59:59 CEST
                  Sun, 2012-10-28 02:00:00 CET
 Next DST change: CET → CEST, DST will become active
                  the clock will jump one hour forward
                  Sun, 2013-03-31 01:59:59 CET
                  Sun, 2013-03-31 03:00:00 CEST
                </programlisting>
                </para>

                <para>Enable an NTP daemon (chronyd):
                <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 chronyd.service
chronyd.service - NTP client/server
          Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled)
          Active: active (running) since Fri, 2012-11-02 09:36:25 CET; 5s ago
...
                </programlisting>
                </para>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><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>
                </para>
        </refsect1>

</refentry>