man > systemd-halt.service(8)

SYSTEMD-POWEROFF.SERVICE(8)           systemd-poweroff.service           SYSTEMD-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 255                                                              SYSTEMD-POWEROFF.SERVICE(8)