Terminal commands for hard- reboot & shutdown

So i had the unfortunate scenario where I could not reboot or shutdown a Ubuntu server via the command line and no "out of band" access methods were available.

Luckily the following saved me:

Terminal command for hard-shutdown

sudo sh -c "echo o > /proc/sysrq-trigger"

Terminal command for hard-restart

sudo sh -c "echo b > /proc/sysrq-trigger"