Home > Tutorial > Fix a Frozen System with the Magic SysRq Keys

Fix a Frozen System with the Magic SysRq Keys

September 11, 2007 Leave a comment Go to comments

You finally got your Linux environment to crash. Ctrl+Alt+Backspace does nothing, nor do the F-keys. You know you shouldn’t have installed that bad driver, but you did it anyway.

So you reach for the power button.

Stop.

Mashing in the power button to reboot could cause a problem if your hard drive is still being written to, and usually causes more problems than it solves. The Linux kernel includes a secret method of restarting your PC should it ever stop doing its job.

  1. Hold down the Alt and SysRq (Print Screen) keys.
  2. While holding those down, type the following in order. Nothing will appear to happen until the last letter is pressed: REISUB
  3. Watch your computer reboot magically.

What the individual keys do in that sequence are not as important as what it does as a whole: stops all programs, unmounts all drives, and reboots. A lot safer than just cutting the power.

Here it is again: REISUB. Remember that, as it will save you a lot of time when you are configuring a system and something gets messed up. Need a mnemonic? Try Raising Elephants Is So Utterly Boring.

As an aside, don’t try this if you just want to reboot. A normal reboot, if it can be done, should always be used instead of the REISUB keys.

REISUB

Categories: Tutorial Tags:
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: