In some cases, Kernel’s emergency keys can entry in conflit with others funcionalities in Ubuntu, for example, screenshot. It uses Alt + Prt Sc to get current window. Prt Sc and Sys Rq is the same key.
However, to disable them, open the file /etc/sysctl.conf as root privileges and change or append the line below to the end of the file.
Now, open the terminal and run:
sudo sysctl -p
The command above will reload the settings. To do the test, try to use one of the combination keys shown in Kernel’s Emergency keys in Ubuntu.
To finish, you must be thinking what mean kernel.sysrq=0. Don’t worry, below is the meaning of each possible values.
0 –> Disable all Sys Rq
1 –> Enable Sys Rq completely
2 –> Enable control of console logging level
4 –> Control of keyboard (SAK, unraw)
8 –> Enable debugging dumps of processes etc.
16 –> Enable sync command
32 –> Enable remount read-only
64 –> Enable signalling of processes (term, kill, oom-kill)
128 –> Allow reboot/poweroff
256 –> Allow nicing of all RT tasks
More information about that you can find in http://en.wikipedia.org/wiki/Magic_SysRq_key.
That’s it. See you next time.