NAME

       systemd-halt.service, systemd-poweroff.service, systemd-reboot.service, systemd-kexec.service, systemd-
       shutdown - System shutdown logic

SYNOPSIS

       systemd-halt.service

       systemd-poweroff.service

       systemd-reboot.service

       systemd-kexec.service

       /lib/systemd/systemd-shutdown

       /lib/systemd/system-shutdown/

DESCRIPTION

       systemd-halt.service is a system service that is pulled in by halt.target and is responsible for the
       actual system halt. Similarly, systemd-poweroff.service is pulled in by poweroff.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 /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, 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.

       Immediately before executing the actual system halt/poweroff/reboot/kexec systemd-shutdown will run all
       executables in /lib/systemd/system-shutdown/ and pass one arguments to them: either "halt", "poweroff",
       "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 systemd-halt.service (and the related units) should never be executed directly. Instead,
       trigger system shutdown with a command such as "systemctl halt" or suchlike.

SEE ALSO

       systemd(1), systemctl(1), systemd.special(7), reboot(2), systemd-suspend.service(8), bootup(7)