The Magic SysRq key

I read an article on fosswire about reisub via digg. Refreshing my memory on this kernel trick. The Magic SysRq key allows you to input basic low level commands. So if somehow your desktop froze you don't need to hit the power button. The kernel will still be alive under all those programs/processes. By holding Alt and SysRq, thats the print screen button, and typing REISUB. You can restart your pc.

REISUB is actually several low level commands:

1. Alt + SysRq + R – takes the keyboard out of raw mode.
2. Alt + SysRq + E – terminates all processes (except init).
3. Alt + SysRq + I – kills all processes (except init).
4. Alt + SysRq + S – synchronizes the disk.
5. Alt + SysRq + U – remounts all filesystems read-only.
6. Alt + SysRq + B – reboots the machine.

For other low level commands have a look at Magic SysRq key on wiki. Some of them I didn't even know.