Bdtyktl

poweroff complains that it can't connect to systemd via DBus (of course, it's not alive). I did sync followed by kill $$, thinking that pid 1 dying would cue the kernel to poweroff, but that caused a kernel panic. I then held the power button to force the poweroff.

What's the most proper way to power-off in this scenario?

1. Unmount the filesystems that you had mounted. The root filesystem is a special case; for this you can use mount / -o remount,ro. umount / also happens to work on Linux, because it is effectively converted to the former command.


2. poweroff -f

The systemd-specific equivalent of poweroff -f is systemctl poweroff -f -f.

That said, you don't need to worry about it too much, unless

1. You have mounted an old filesystem like FAT - as used by the EFI system partition - or ext2, which does not implement journalling or equivalent. With a modern filesystem, sync is supposed to be enough, and the filesystem will recover quickly on the next boot.


2. or you might have left a running process that writes to the filesystem, and you had intended to shut it down cleanly. In that case it's useful to umount the filesystems, because it will show a busy error to remind you about the remaining writer.

Ok, so it just occurred to me that I had the option to exec init. From there, I would probably be able to later poweroff. I wonder if there are better alternatives, though.

#exec /sbin/init 

is what I use when I can't use "init 0" or any init command which is usually in single user mode to change root passwd.