Provided by: systemd_251.4-1ubuntu7_amd64 bug


       systemd-suspend.service, systemd-hibernate.service, systemd-hybrid-sleep.service, systemd-
       suspend-then-hibernate.service, systemd-sleep - System sleep state logic








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

       Immediately before entering system suspend and/or hibernation systemd-suspend.service (and
       the other mentioned units, respectively) will run all executables in
       /lib/systemd/system-sleep/ and pass two arguments to them. The first argument will be
       "pre", the second either "suspend", "hibernate", "hybrid-sleep", or
       "suspend-then-hibernate" depending on the chosen action. An environment variable called
       "SYSTEMD_SLEEP_ACTION" will be set and contain the sleep action that is processing. This
       is primarily helpful for "suspend-then-hibernate" where the value of the variable will be
       "suspend", "hibernate", or "suspend-after-failed-hibernate" 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 "post". All executables in this directory are
       executed in parallel, and execution of the action is not continued until all executables
       have finished.

       Note that scripts or binaries dropped in /lib/systemd/system-sleep/ 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 Inhibitor interface[1].

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

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


       systemd-sleep understands the following commands:

       -h, --help
           Print a short help text and exit.

           Print a short version string and exit.

       suspend, hibernate, suspend-then-hibernate, hybrid-sleep
           Suspend, hibernate, suspend then hibernate, or put the system to hybrid sleep.


       systemd-sleep.conf(5), systemd(1), systemctl(1), systemd.special(7), systemd-


        1. Inhibitor interface