- <filename>systemd-suspend.service</filename> and
- <filename>systemd-hibernate.service</filename> should
- never be executed directly. Instead, trigger system
- sleep states with a command such as "<literal>systemctl
- suspend</literal>" or suchlike.</para>
+ <filename>systemd-suspend.service</filename>,
+ <filename>systemd-hibernate.service</filename> and
+ <filename>systemd-hybrid-sleep.service</filename>
+ should never be executed directly. Instead, trigger
+ system sleep states with a command such as
+ "<literal>systemctl suspend</literal>" or
+ similar.</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.</para>