My computer is running Ubuntu from a Live CD and is frozen to the point where I can't even turn num lock on and off. Does the Magic SysRq key work even now? And is it something that's enables by default or does it need to be enabled by the user?

2 Answers 2


The kernel itself has certain key combinations that should be able to get you out of a frozen pickle like: ALT GR + PRT SC + K to force a log out, or ALT GR + PRT SC + O to force a safe shutdown...

  • Does it work even if the computer doesn't seem to be recognizing keyboard input?
    – Rayman
    Aug 14, 2014 at 16:23
  • Sometimes, depends on the actual error that causes hang...
    – TenPlus1
    Aug 18, 2014 at 5:39

The SysRq key codes are enabled by default and can be disabled.

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