1SYSTEMD-HALT.SERVICE(8)      systemd-halt.service      SYSTEMD-HALT.SERVICE(8)
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NAME

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

10       systemd-halt.service
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12       systemd-poweroff.service
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14       systemd-reboot.service
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16       systemd-kexec.service
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18       /usr/lib/systemd/systemd-shutdown
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DESCRIPTION

21       systemd-halt.service is a system service that is pulled in by
22       halt.target and is responsible for the actual system halt. Similarly,
23       systemd-poweroff.service is pulled in by poweroff.target,
24       systemd-reboot.service by reboot.target and systemd-kexec.service by
25       kexec.target to execute the respective actions.
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27       When these services are run, they ensure that PID 1 is replaced by the
28       /usr/lib/systemd/systemd-shutdown tool which is then responsible for
29       the actual shutdown. Before shutting down, this binary will try to
30       unmount all remaining file systems, disable all remaining swap devices,
31       detach all remaining storage devices and kill all remaining processes.
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33       It is necessary to have this code in a separate binary because
34       otherwise rebooting after an upgrade might be broken — the running PID
35       1 could still depend on libraries which are not available any more,
36       thus keeping the file system busy, which then cannot be re-mounted
37       read-only.
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39       Immediately before executing the actual system
40       halt/poweroff/reboot/kexec systemd-shutdown will run all executables in
41       /usr/lib/systemd/system-shutdown/ and pass one arguments to them:
42       either "halt", "poweroff", "reboot" or "kexec", depending on the chosen
43       action. All executables in this directory are executed in parallel, and
44       execution of the action is not continued before all executables
45       finished.
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47       Note that systemd-halt.service (and the related units) should never be
48       executed directly. Instead, trigger system shutdown with a command such
49       as "systemctl halt" or suchlike.
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SEE ALSO

52       systemd(1), systemctl(1), systemd.special(7), reboot(2), systemd-
53       suspend.service(8)
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57systemd 219                                            SYSTEMD-HALT.SERVICE(8)
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