Wie plant systemctl das Herunterfahren des Systems?

2645
patryk.beza

Wenn ich shutdown -h +30tippe, plant Linux irgendwie die Änderung des Runlevels innerhalb von 30 Minuten. Unter Debian gibt /sbin/shutdownes einen symbolischen Link zu /bin/systemctl. Meine Tests zeigen, dass shutdownsich nicht weder verwenden cron noch systemd Timer .

Wie wird das System heruntergefahren systemd?

9
Kannst du die Frage klären? Ich glaube nicht, dass ich es verstehe. Konrad Gajewski vor 8 Jahren 0

1 Antwort auf die Frage

9
bertieb

Good question. I tried what I now realise you must have tried- scheduling a shutdown and querying the systemd timers!

That showed that the shutdown was not in the systemd timers, as you noted. So then a quick perusal of the systemctl source gives us this call, as part of halt_main():

r = sd_bus_call_method( b, "org.freedesktop.login1", "/org/freedesktop/login1", "org.freedesktop.login1.Manager", "ScheduleShutdown", &error, NULL, "st", arg_action == ACTION_HALT ? "halt" : arg_action == ACTION_POWEROFF ? "poweroff" : arg_action == ACTION_KEXEC ? "kexec" : "reboot", arg_when);

(systemctl.c line 7387)

So it would appear that shutdowns are handled by logind. You can continue to pursue the details if you like- see login-dbus.c. There are methods there for scheduling, cancelling, managing shutdowns. But for a deeper understanding, you may need to know more about logind/systemd than I do.

Long story short, the shutdown info is stored (at least) in a schedule file at /run/systemd/shutdown/scheduled, the contents of mine as an example were:

USEC=1435715559055789 WARN_WALL=1 MODE=poweroff

Indicating time (in microseconds, presumably); whether to warn via wall, and which mode (cf restart, kexec etc).

Hope this points you in the right direction at least!

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