Mostly just a post so I don’t lose this information again in the future… I have a headless machine that I use as a file server amongst other things and I have found that after a system update it now reboots after a two second delay when issued with the “poweroff” command. This post is the answer:
The article is a bit out-of-date and not directly relevant to my circumstances, but the script provided works perfectly:
case “$1” in
stop) for i in /sys/bus/*/devices/*/power/control ; do echo on > $i ; done
Put this in “/etc/rc0.d/K32power-control-on” and give it execute permissions and it works like a charm. Many thanks to the user “Inspired”.