"The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low level commands regardless of the system's state. It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem."This is for safely reboot a frozen system: hold "alt + sysrq" and then sequentially: R -> E -> I -> S -> U -> B
This can be used to kill x: alt + sysrq + K
I hope we never have to use this ;-) .
