How to force Mac to into dirty shutdown state on every power off?

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Problem :

As Far as I can tell no one has actually solved this debacle. How do you get a mac mini to power on every time the UPS it is connected to restores power? It is easy enough to have the UPS communicate that power is about to turn off so have the mac run the command halt -u, or shutdown -h -u, etc, and many solutions such as powerchute from APC guarantee that it will shutdown etc. But it is not guaranteed that the mac will turn back on. If this bit/ file was permanently set so mac the mac believed that it dirty shutdown every time, whatever hardware is responsible for the power sensing of the power restored would always boot the mac when power is restored, even if the mini was powered off during while it booted. Currently if your mini powers off without dirty shutdown being set you are boned, and you must physically press the power button on the back for it to restart, which is unacceptable if the mini is says 5000 miles away or at the bottom of the ocean. You should be able to get this functionality even if no UPS is involved just by having the mac always try to reboot when power is restored. Has anyone ever figured this out?

Solution :

Make sure you only shut down with shutdown -u, and be sure to disconnect power within the next 5 minutes. And, of course, make sure to keep “Start up automatically after a power failure” checked in System Preferences > Energy Saver.

If you try to keep that “dirty” bit set when doing a normal shutdown, it will automatically reboot the moment it finishes shutting down, unless you can magically yank power at just the right moment.

Apple’s only modern hardware designed to be booted remotely is the Xserve server, which supports Lights Out Management (LOM). See ipmitool(1) for more information.

If waiting up to 24 hours before restart is an option, you can turn on “Start Up or Wake” in System Preferences => Energy Saver => Schedule.

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