REISUB - the gentle Linux restart

According to Lifehacker a frozen Linux system that’s not responding to the Ctrl-Alt-Delete three-finger-salute can be restarted more safely than by pushing the power button, which is usually the next step.

Holding down Alt and SysRq (which is the Print Screen key) while slowly typing REISUB will get you safely restarted. REISUO will do a shutdown rather than a restart.

Sounds like either an April Fools joke or some very strange magic akin to the old BIOS beeps we used to use to diagnose PC faults so bad that nothing would boot. Wikipedia comes to the rescue with an in-depth listing of all the SysRq keys.

  • R: Switch the keyboard from raw mode to XLATE mode
  • E: Send the SIGTERM signal to all processes except init
  • I: Send the SIGKILL signal to all processes except init
  • S: Sync all mounted filesystems
  • U: Remount all mounted filesystems in read-only mode
  • B: Immediately reboot the system, without unmounting partitions or syncing

(Discovered originally here)

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  1. Raising Elephants Is So Utterly Boring is a good mnemonic aid for the REISUB combo

    — Björn · Tue 01 Dec 2009 · #

  2. I like it! What a great idea.

    — Andrew Kember · Wed 02 Dec 2009 · #

  3. “Reboot Even If System Utterly Broken” seems a little more apt…

    — Jacob · Tue 22 Dec 2009 · #

  4. Very good. A tailor-made mnemonic.

    — Andrew Kember · Tue 22 Dec 2009 · #

  5. uh, it’s “busier”, backwards. as in i’d be busier if this ******* system wasn’t so broken. wtf do elephants have to do with it?

    — mnemonic help, anyone?? · Sat 26 Dec 2009 · #

  6. I never knew such commands existed! I’m going to have to remember this next time a linux server explodes, thankyou!

    — Timos · Thu 14 Jan 2010 · #

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