systemd-suspend.service, systemd-hibernate.service, systemd-hybrid-sleep.service, systemd-suspend-then-hibernate.service, systemd-sleep — System sleep state logic
systemd-suspend.service
systemd-hibernate.service
systemd-hybrid-sleep.service
systemd-suspend-then-hibernate.service
/usr/lib/systemd/system-sleep
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.
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
/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
interface.
Note that
systemd-suspend.service
,
systemd-hibernate.service
, and
systemd-hybrid-sleep.service
systemd-suspend-then-hibernate.service
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-sleep.conf(5).