daemon. Use of this option is
recommended for services where
<varname>Type=</varname> is set to
- <option>forking</option>.</para>
+ <option>forking</option>. systemd will
+ read the PID of the main process of
+ the daemon after start-up of the
+ service. systemd will not write to the
+ file configured here.</para>
</listitem>
</varlistentry>
<para>Socket units may be used to implement on-demand
starting of services, as well as parallelized starting
of services.</para>
+
+ <para>Note that the daemon software configured for
+ socket activation with socket units needs to be able
+ to accept sockets from systemd, either via systemd's
+ native socket passing interface (see
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for details) or via the traditional
+ <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>-style
+ socket passing (i.e. sockets passed in via STDIN and
+ STDOUT, using <varname>StandardInput=socket</varname>
+ in the service file).</para>
</refsect1>
<refsect1>