In macOS 14.0 and earlier, the shutdown command had a -u choice for dealing with UPS-initiated emergency shutdowns. From the person web page of 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 unclean shutdown to allow a later automated energy on. OS X makes use of this mode robotically with supported UPSs in emergency shutdowns.
On macOS 14.4 and later, this feature was eliminated. The truth is, Apple publishes the supply code of the shutdown utility on GitHub, and commit 49dcc07 (“14.4”) successfully removes all code that handles the -u choice.
Certain sufficient, by shutting down a machine working macOS 14.4 or later with command shutdown -uh now, the 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 (working macOS 15.1) robotically shut down. I waited for the UPS to fully run out of battery and, once I plugged it again in, the Mac mini did not restart, even when the “Begin up robotically after an influence failure” choice is enabled in Settings.
If my expertise is confirmed, it signifies that Apple didn’t simply take away the choice to manually simulate a unclean shutdown, however they eliminated the characteristic solely, even within the case of precise UPS-initiated shutdowns.
Does anyone have insights on why this characteristic was eliminated, and the way can we set off a unclean shutdown on macOS 14.4 or later?
As of now, it seems to be like there isn’t a manner of robotically restarting a desktop Mac after an emergency shutdown.