path: root/man/systemd.special.xml

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<refentry id="systemd.special">

        <refentryinfo>
                <title>systemd.special</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.special</refentrytitle>
                <manvolnum>7</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>systemd.special</refname>
                <refpurpose>special systemd units</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <para><filename>emergency.service</filename></para>
                <para><filename>local-fs.target</filename></para>
                <para><filename>network.target</filename></para>
                <para><filename>nss-lookup.target</filename></para>
                <para><filename>remote-fs.target</filename></para>
                <para><filename>rpcbind.target</filename></para>
                <para><filename>rtc-set.target</filename></para>
                <para><filename>shutdown.target</filename></para>
                <para><filename>sigpwr.target</filename></para>
                <para><filename>sockets.target</filename></para>
                <para><filename>swap.target</filename></para>
                <para><filename>syslog.target</filename></para>
                <para><filename>systemd-initctl.service</filename></para>
                <para><filename>systemd-initctl.socket</filename></para>
                <para><filename>systemd-logger.service</filename></para>
                <para><filename>systemd-logger.socket</filename></para>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para>A few units are treated specially by
                systemd. They have special internal semantics and
                cannot be renamed.</para>
        </refsect1>

        <refsect1>
                <title>Special System Units</title>

                <variablelist>
                        <varlistentry>
                                <term><filename>emergency.service</filename></term>
                                <listitem>
                                        <para>A special service unit
                                        that starts an emergency
                                        shell on the main
                                        console. This unit is supposed
                                        to be used with the kernel
                                        command line option
                                        <varname>systemd.default=</varname>
                                        and has otherwise little use.
                                        </para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>local-fs.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to all mount units that
                                        refer to local mount
                                        points. In addition, systemd
                                        adds dependencies of type
                                        Wants to those mounts listed
                                        in
                                        <filename>/etc/fstab</filename>
                                        that have the
                                        <literal>auto</literal> and
                                        <literal>comment=systemd.mount</literal>
                                        mount options set.</para>

                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$local_fs</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>network.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$network</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>nss-lookup.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$named</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>remote-fs.target</filename></term>
                                <listitem>
                                        <para>Similar to <filename>local-fs.target</filename>, but for remote mount points.</para>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$remote-fs</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>rpcbind.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$rpcbind</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>rtc-set.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$time</literal>
                                        facility.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>shutdown.target</filename></term>
                                <listitem>
                                        <para>A special target unit
                                        that terminates the services
                                        on system shutdown.</para>

                                        <para>Services that shall be
                                        terminated on system shutdown
                                        shall add Wants dependencies
                                        from this unit to their
                                        service unit during
                                        installation.</para>

                                        <para>systemd automatically
                                        adds dependencies of type
                                        Conflicts to this target unit
                                        for all SysV init scripts that
                                        shall be terminated in SysV
                                        runlevels 0 or 6.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>sigpwr.target</filename></term>
                                <listitem>
                                        <para>A special target that is
                                        started when systemd receives
                                        the SIGPWR process signal,
                                        which is normally sent by the
                                        kernel or UPS daemons when the
                                        power fails.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>sockets.target</filename></term>
                                <listitem>
                                        <para>A special target unit
                                        that sets up all service
                                        sockets.</para>

                                        <para>Services that can be
                                        socket-activated shall add
                                        Wants dependencies from this
                                        unit to their socket unit
                                        during installation.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>swap.target</filename></term>
                                <listitem>
                                        <para>Similar to
                                        <filename>local-fs.target</filename>, but for swap
                                        partitions and swap
                                        files.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>syslog.target</filename></term>
                                <listitem>
                                        <para>systemd automatically
                                        adds dependencies of type
                                        After to this target unit for
                                        all SysV init scripts with an
                                        LSB header referring to the
                                        <literal>$syslog</literal>
                                        facility.</para>

                                        <para>Administrators should
                                        ensure that this target pulls
                                        in a service unit with the
                                        name or alias of
                                        <filename>@SPECIAL_SYSLOG_NAME@</filename> (or a
                                        socket unit that activates
                                        this service).</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>systemd-initctl.service</filename></term>
                                <listitem>
                                        <para>This provides
                                        compatibility with the SysV
                                        /dev/initctl file system FIFO
                                        for communication with the
                                        init system.</para>
                                        <para>This is a
                                        socket-activated service, see
                                        <filename>system-initctl.socket</filename>.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>systemd-initctl.socket</filename></term>
                                <listitem>
                                        <para>Socket activation unit
                                        for
                                        <filename>system-initctl.service</filename>.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>systemd-logger.service</filename></term>
                                <listitem>
                                        <para>This is used internally
                                        by systemd to provide syslog
                                        logging to started
                                        processes.</para>
                                        <para>This is a
                                        socket-activated service, see
                                        <filename>system-logger.socket</filename>.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><filename>systemd-logger.socket</filename></term>
                                <listitem>
                                        <para>Socket activation unit
                                        for
                                        <filename>system-logger.service</filename>.</para>
                                </listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Special Session Units</title>

                <para>When systemd runs as a service instance, the
                following special units are available, which have
                similar definitions as their system counterparts:
                <filename>local-fs.target</filename>,
                <filename>remote-fs.target</filename>,
                <filename>shutdown.target</filename>,
                <filename>sockets.target</filename>,
                <filename>swap.target</filename>.</para>
        </refsect1>

        <refsect1>
                  <title>See Also</title>
                  <para>
                          <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                          <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                          <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                          <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                  </para>
        </refsect1>

</refentry>