1SYSTEMD-HALT.SERVICE(8) systemd-halt.service SYSTEMD-HALT.SERVICE(8)
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6 systemd-halt.service, systemd-poweroff.service, systemd-reboot.service,
7 systemd-kexec.service, systemd-shutdown - System shutdown logic
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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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20 /usr/lib/systemd/system-shutdown/
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23 systemd-halt.service is a system service that is pulled in by
24 halt.target and is responsible for the actual system halt. Similarly,
25 systemd-poweroff.service is pulled in by poweroff.target,
26 systemd-reboot.service by reboot.target and systemd-kexec.service by
27 kexec.target to execute the respective actions.
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29 When these services are run, they ensure that PID 1 is replaced by the
30 /usr/lib/systemd/systemd-shutdown tool which is then responsible for
31 the actual shutdown. Before shutting down, this binary will try to
32 unmount all remaining file systems, disable all remaining swap devices,
33 detach all remaining storage devices and kill all remaining processes.
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35 It is necessary to have this code in a separate binary because
36 otherwise rebooting after an upgrade might be broken — the running PID
37 1 could still depend on libraries which are not available any more,
38 thus keeping the file system busy, which then cannot be re-mounted
39 read-only.
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41 Immediately before executing the actual system
42 halt/poweroff/reboot/kexec systemd-shutdown will run all executables in
43 /usr/lib/systemd/system-shutdown/ and pass one arguments to them:
44 either "halt", "poweroff", "reboot" or "kexec", depending on the chosen
45 action. All executables in this directory are executed in parallel, and
46 execution of the action is not continued before all executables
47 finished.
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49 Note that systemd-halt.service (and the related units) should never be
50 executed directly. Instead, trigger system shutdown with a command such
51 as "systemctl halt" or suchlike.
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54 systemd(1), systemctl(1), systemd.special(7), reboot(2), systemd-
55 suspend.service(8), bootup(7)
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59systemd 246 SYSTEMD-HALT.SERVICE(8)