systemd/man/systemd.slice.xml

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<refentry id="systemd.slice">
  <refentryinfo>
    <title>systemd.slice</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>systemd.slice</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd.slice</refname>
    <refpurpose>Slice unit configuration</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename><replaceable>slice</replaceable>.slice</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>A unit configuration file whose name ends in
    <literal>.slice</literal> encodes information about a slice which
    is a concept for hierarchically managing resources of a group of
    processes. This management is performed by creating a node in the
    Linux Control Group (cgroup) tree. Units that manage processes
    (primarily scope and service units) may be assigned to a specific
    slice. For each slice, certain resource limits may be set that
    apply to all processes of all units contained in that
    slice. Slices are organized hierarchically in a tree. The name of
    the slice encodes the location in the tree. The name consists of a
    dash-separated series of names, which describes the path to the
    slice from the root slice. The root slice is named,
    <filename>-.slice</filename>. Example:
    <filename>foo-bar.slice</filename> is a slice that is located
    within <filename>foo.slice</filename>, which in turn is located in
    the root slice <filename>-.slice</filename>.
    </para>

    <para>Note that slice units cannot be templated, nor is possible to add multiple names to a slice unit by creating
    additional symlinks to it.</para>

    <para>By default, service and scope units are placed in
    <filename>system.slice</filename>, virtual machines and containers
    registered with
    <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    are found in <filename>machine.slice</filename>, and user sessions
    handled by
    <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    in <filename>user.slice</filename>. See
    <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    for more information.</para>

    <para>See
    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    for the common options of all unit configuration
    files. The common configuration items are configured
    in the generic [Unit] and [Install] sections. The
    slice specific configuration options are configured in
    the [Slice] section. Currently, only generic resource control settings
    as described in
    <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> are allowed.
    </para>

    <para>See the <ulink
    url="https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/">New
    Control Group Interfaces</ulink> for an introduction on how to make
    use of slice units from programs.</para>
  </refsect1>

  <refsect1>
    <title>Automatic Dependencies</title>

    <para>Slice units automatically gain dependencies of type
    <varname>After=</varname> and <varname>Requires=</varname> on
    their immediate parent slice unit.</para>

    <para>Unless <varname>DefaultDependencies=false</varname> is used in the <literal>[Unit]</literal> section, slice
    units will implicitly have dependencies of type <varname>Conflicts=</varname> and <varname>Before=</varname> on
    <filename>shutdown.target</filename>. These ensure that slice units are removed prior to system shutdown. Only
    slice units involved with early boot or late system shutdown should disable this option.
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>