In macOS 14.0 and earlier, the shutdown command had a -u choice to deal with emergency shutdowns initiated by UPS. From the person web page shutdown on an previous Mac:
-u The system is halted up till the purpose of eradicating system energy, however waits earlier than eradicating energy for five minutes in order that an exterior UPS (uninterruptible energy provide) can forcibly take away energy. This simulates a grimy shutdown to allow a later automated energy on. OS X makes use of this mode routinely with supported UPSs in emergency shutdowns.
In macOS 14.4 and later, this feature was eliminated. In actual fact, Apple publishes the supply code of the shutdown utility on GitHuband commit 49dcc07 (“14.4”) successfully removes all code that handles the -u possibility.
Successfully shutting down a machine operating macOS 14.4 or later with the command shutdown -uh nowThe next message is printed to the console:
shutdown: -u has no impact
Anecdotally, I can say that I simulated an influence loss on my UPS till my Mac mini (operating macOS 15.1) routinely shut down. I waited for the UPS to utterly run out of battery, and after I plugged it again in, the Mac mini did. No restart, even when the “Begin routinely after an influence outage” possibility is enabled in Settings.
If my expertise is confirmed, it implies that Apple didn’t merely take away the choice to by hand They simulated a grimy shutdown, however eliminated the function fully, even within the case of precise UPS-initiated shutdowns.
How can we trigger a grimy shutdown in macOS 14.4 or later?
As of now, there seems to be no technique to routinely restart a desktop Mac after an emergency shutdown.
