SYSTEMD-SUSPEND.SERVICE(8) systemd-suspend.service SYSTEMD-SUSPEND.SERVICE(8)
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
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 /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. 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.
Note that systemd-suspend.service, systemd-hibernate.service, and
should never be executed directly. Instead, trigger system sleep states
with a command such as "systemctl suspend" or similar.
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-
systemd-sleep understands the following commands:
Print a short help text and exit.
Print a short version string and exit.
suspend, hibernate, hybrid-sleep, suspend-then-hibernate
Suspend, hibernate, suspend then hibernate, or put the system to
systemd-sleep.conf(5), systemd(1), systemctl(1), systemd.special(7),
1. Inhibitor interface
systemd 237 SYSTEMD-SUSPEND.SERVICE(8)
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