Restart frozen system with Magic SysRq key

Warning: Doing this implies that you understand that changing things as root (system administrator) means that you understand what you are doing. Also that you have some ability to deal with problems should any occur. Should you encounter difficulty post your issue in forum with a descriptive title and enough accurate information so someone can help. For serious technical issues file a bug report. For faster response user should use OpenMandriva Chat.

The procedure:

Magic SysRq key is a way to restart a frozen system among other things. To restart a frozen system we use the key combination (most computers with QWERTY kbd):

Alt+SysRq+ in order reisub or Alt+PrtScn+ in order reisub

The mnemonic “Raising Elephants Is So Utterly Boring” is often used to remember this sequence. The combinations always assume the QWERTY keyboard layout. As always there are some computers that use some other key combination. Read the articles to find yours if the 2 above do not work.

Linux Magic System Request Key Hacks

Wikipedia Magic SysRq key

You can find more about this with your own internet search.

The Magic SysRq key is a kernel setting that is disabled by default by kernel developers upstream. To check if this is enabled on your system:

$ cat /proc/sys/kernel/sysrq
0

0 means disabled if you see 1 that means these are enabled.

To enable this:

sudo echo "1" > /proc/sys/kernel/sysrq

To disable:

sudo echo "0" > /proc/sys/kernel/sysrq

If that command should not work then this will. Create a file /etc/sysctl.d/51-local-sysreq.conf with:

#!/bin/bash

kernel.sysrq = 1

You can do this with Vim or in Konsole with vim or nano. Less technical users may prefer nano. Example:

Ctrl+o to write then Ctrl+x to exit. Then when you reboot you should have the Magic SysRq key enabled.

To check:

What does the key combination we gave you to restart a frozen system do:

  • r – Puts the keyboard into raw mode, taking control of it away from the X server.
  • e – Sends the terminate signal to all processes, asking them to end gracefully.
  • i – Sends the kill signal to all processes, forcing them to end immediately.
  • s – Flushes data from your cache to disk.
  • u – Remounts all file systems read-only.
  • b – Reboots your computer.

Note: Plasma desktop users can create the file using Kate or Kwrite. You will be asked for administrator password in order to save the file.