Linux za Sve forum

Although most Linux distros are stable, there are some hard times when your system hangs, and leaves you in a frozen state. Your mouse, keyboard may not work, and so, you are unable to shutdown safely. At most of the time at these situations, we mostly reboot, but such force shutdowns may be harmful for your hard disk drives. There is a simple way where you can safely reboot your Linux box when it becomes unresponsive.

To do so, you will need to press the Alt key and SysRq key together. The SysRq key is mostly located at the topmost row of your keyboard, somewhere near the number keys. Now hold down Alt and keeping it pressed, press the SysRq key. Now you need to type reisub with your other hand. Make sure you keep a gap of few seconds between each letters while typing, this will ensure all the actions are completed successfully. The meaning of each key press are given below:

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.

You can learn more about this feature here.

For this to work, SysRq must be enabled in your kernel. To check it, type this in terminal:

cat /proc/sys/kernel/sysrq

If the above command returns 1, it is activated, otherwise you will need to enable it using

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