Makes certain low-level commands available "no matter what" (usually), such as dropping disk caches, unmounting, or rebooting.
aka System request
How to use SysRq ∞
Tap the hotkey you wish
Rebooting, no matter what ∞
|unRaw||(take control of keyboard back from X),|
|tErminate||(send SIGTERM to all processes, allowing them to terminate gracefully),|
|kIll||(send SIGKILL to all processes, forcing them to terminate immediately),|
|Sync||(flush data to disk),|
|Unmount||(remount all filesystems read-only),|
I've had my system hang on the LILO screen when rebooting, forcing a hard reboot.