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 257.9 SYSTEMD-SUSPEND.SERVICE(8)
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