systemd/man/systemd-suspend.service.xml

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<refentry id="systemd-suspend.service"
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-suspend.service</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-suspend.service</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-suspend.service</refname>
    <refname>systemd-hibernate.service</refname>
    <refname>systemd-hybrid-sleep.service</refname>
    <refname>systemd-suspend-then-hibernate.service</refname>
    <refname>systemd-sleep</refname>
    <refpurpose>System sleep state logic</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><simplelist>
      <member><filename>systemd-suspend.service</filename></member>
      <member><filename>systemd-hibernate.service</filename></member>
      <member><filename>systemd-hybrid-sleep.service</filename></member>
      <member><filename>systemd-suspend-then-hibernate.service</filename></member>
      <member><filename>/usr/lib/systemd/system-sleep</filename></member>
    </simplelist></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><filename>systemd-suspend.service</filename> is a system
    service that is pulled in by <filename>suspend.target</filename>
    and is responsible for the actual system suspend. Similarly,
    <filename>systemd-hibernate.service</filename> is pulled in by
    <filename>hibernate.target</filename> to execute the actual
    hibernation. Finally,
    <filename>systemd-hybrid-sleep.service</filename> is pulled in by
    <filename>hybrid-sleep.target</filename> to execute hybrid
    hibernation with system suspend and pulled in by
    <filename>suspend-then-hibernate.target</filename> to execute system suspend
    with a timeout that will activate hibernate later.</para>

    <para>Immediately before entering system suspend and/or
    hibernation <filename>systemd-suspend.service</filename> (and the
    other mentioned units, respectively) will run all executables in
    <filename>/usr/lib/systemd/system-sleep/</filename> and pass two
    arguments to them. The first argument will be
    <literal>pre</literal>, the second either
    <literal>suspend</literal>, <literal>hibernate</literal>,
    <literal>hybrid-sleep</literal>, or <literal>suspend-then-hibernate</literal>
    depending on the chosen action. An environment variable called <literal>SYSTEMD_SLEEP_ACTION</literal>
    will be set and contain the sleep action that is processing. This is primarily helpful for
    <literal>suspend-then-hibernate</literal> where the value of the variable will be <literal>suspend</literal>, <literal>hibernate</literal>,
    or <literal>suspend-after-failed-hibernate</literal> in cases where hibernation has failed.
    Immediately after leaving system suspend and/or hibernation the
    same executables are run, but the first argument is now
    <literal>post</literal>. All executables in this directory are
    executed in parallel, and execution of the action is not continued
    until all executables have finished. Note that <filename>user.slice</filename> will
    be frozen while the executables are running, so they should not attempt to
    communicate with any user services expecting a reply.</para>

    <para>Note that scripts or binaries dropped in
    <filename>/usr/lib/systemd/system-sleep/</filename> are intended
    for local use only and should be considered hacks. If applications
    want to react to system suspend/hibernation and resume, they should rather use the
    <ulink url="https://systemd.io/INHIBITOR_LOCKS">Inhibitor Locks</ulink>.</para>

    <para>Note that <filename>systemd-suspend.service</filename>,
    <filename>systemd-hibernate.service</filename>, <filename>systemd-hybrid-sleep.service</filename>, and
    <filename>systemd-suspend-then-hibernate.service</filename> should never be executed directly. Instead,
    trigger system sleep with a command such as <command>systemctl suspend</command> or <command>systemctl
    hibernate</command>.</para>

    <para>Internally, this service will echo a string like
    <literal>mem</literal> into <filename>/sys/power/state</filename>,
    to trigger the actual system suspend. What exactly is written
    where can be configured in the [Sleep] section
    of <filename>/etc/systemd/sleep.conf</filename> or a
    <filename>sleep.conf.d</filename> file. See
    <citerefentry><refentrytitle>systemd-sleep.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>

    <para>Note that by default these services freeze <filename>user.slice</filename> while they run. This prevents
    the execution of any process in any of the user sessions while the system is entering into and resuming from
    sleep. Thus, this prevents the hooks in <filename>/usr/lib/systemd/system-sleep/</filename>, or any other process
    for that matter, from communicating with any user session process during sleep.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para><command>systemd-sleep</command> understands the
    following commands:</para>

    <variablelist>
      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />

      <varlistentry>
        <term><option>suspend</option></term>
        <term><option>hibernate</option></term>
        <term><option>suspend-then-hibernate</option></term>
        <term><option>hybrid-sleep</option></term>

        <listitem><para>Suspend, hibernate, suspend then hibernate, or put the
        system to hybrid sleep.</para>

        <xi:include href="version-info.xml" xpointer="v203"/>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd-sleep.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-halt.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>

</refentry>