SYSTEMD-SUSPEND.SERVICE(8)  systemd-suspend.service SYSTEMD-SUSPEND.SERVICE(8)

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

SYNOPSIS
	   systemd-suspend.service
	   systemd-hibernate.service
	   systemd-hybrid-sleep.service
	   systemd-suspend-then-hibernate.service
	   /usr/lib/systemd/system-sleep

DESCRIPTION
       systemd-suspend.service is a system service that is pulled in by
       suspend.target and is responsible for the actual system suspend.
       Similarly, systemd-hibernate.service is pulled in by hibernate.target
       to execute the actual hibernation. Finally,
       systemd-hybrid-sleep.service is pulled in by hybrid-sleep.target to
       execute hybrid hibernation with system suspend and pulled in by
       suspend-then-hibernate.target 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 /usr/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 user.slice will be frozen while the executables are running,
       so they should not attempt to communicate with any user services
       expecting a reply.

       Note that scripts or binaries dropped in /usr/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 Locks[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).

       Note that by default these services freeze user.slice while they run.
       This prevents the execution of any process in any of the user sessions
       while the system is entering into and resuming from sleep. Thus, this
       prevents the hooks in /usr/lib/systemd/system-sleep/, or any other
       process for that matter, from communicating with any user session
       process during sleep.

OPTIONS
       systemd-sleep understands the following commands:

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

       --version
	   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.

	   Added in version 203.

SEE ALSO
       systemd-sleep.conf(5), systemd(1), systemctl(1), systemd.special(7),
       systemd-halt.service(8)

NOTES
	1. Inhibitor Locks
	   https://systemd.io/INHIBITOR_LOCKS

systemd 258					    SYSTEMD-SUSPEND.SERVICE(8)