x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SYSTEMD-POWEROFF.SERVICE(8)systemd-poweroff.serviceSYSTEMD-POWEROFF.SERVICE(8)
NAME
systemd-poweroff.service, systemd-halt.service, systemd-reboot.service,
systemd-kexec.service, systemd-shutdown - System shutdown logic
SYNOPSIS
systemd-poweroff.service
systemd-halt.service
systemd-reboot.service
systemd-kexec.service
/usr/lib/systemd/systemd-shutdown
/usr/lib/systemd/system-shutdown/
DESCRIPTION
systemd-poweroff.service is a system service that is pulled in by
poweroff.target and is responsible for the actual system power-off
operation. Similarly, systemd-halt.service is pulled in by halt.target,
systemd-reboot.service by reboot.target and systemd-kexec.service by
kexec.target to execute the respective actions.
When these services are run, they ensure that PID 1 is replaced by the
/usr/lib/systemd/systemd-shutdown tool which is then responsible for
the actual shutdown. Before shutting down, this binary will try to
unmount all remaining file systems (or at least remount them
read-only), disable all remaining swap devices, detach all remaining
storage devices and kill all remaining processes.
It is necessary to have this code in a separate binary because
otherwise rebooting after an upgrade might be broken -- the running PID
1 could still depend on libraries which are not available any more,
thus keeping the file system busy, which then cannot be re-mounted
read-only.
Shortly before executing the actual system power-off/halt/reboot/kexec
systemd-shutdown will run all executables in
/usr/lib/systemd/system-shutdown/ and pass one arguments to them:
either "poweroff", "halt", "reboot", or "kexec", depending on the
chosen action. All executables in this directory are executed in
parallel, and execution of the action is not continued before all
executables finished. Note that these executables are run after all
services have been shut down, and after most mounts have been detached
(the root file system as well as /run/ and various API file systems are
still around though). This means any programs dropped into this
directory must be prepared to run in such a limited execution
environment and not rely on external services or hierarchies such as
/var/ to be around (or writable).
Note that systemd-poweroff.service (and the related units) should never
be executed directly. Instead, trigger system shutdown with a command
such as "systemctl poweroff".
Another form of shutdown is provided by the systemd-soft-
reboot.service(8) functionality. It reboots only the OS userspace,
leaving the kernel, firmware, and hardware as it is.
SEE ALSO
systemd(1), systemctl(1), systemd.special(7), reboot(2), systemd-
suspend.service(8), systemd-soft-reboot.service(8), bootup(7)
systemd 254 SYSTEMD-POWEROFF.SERVICE(8)
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