So your Linux box has locked up and you can’t get a response… step in SysRq!
This wonderful key is on most keyboards and i bet you’ve hit it a low more times than you realise as it’s usually paired up with the PrtSc (PrintScreen) key. What does it do?
Well it allows you to send system requests to a linux kernel, effectively allowing you to bypass the usual GUI/CLI layers.
Unfortunately to be able to utilise this magic key it has to be compiled into the kernel with the following option enabled CONFIG_MAGIC_SYSRQ. The good news is that the majority of kernels have this option enabled but from a security point of view maybe this isn’t a good thing.
Alt + SysRq + [YourChoice] are the magic key presses required. Shown in the below table are the usual steps you should take to try to rescue a Linux system:
1 2 3 4 5 6 | unRaw - Force any application with keyboard/mouse control to give it back to you tErminate - send SIGTERM to all processes kIll - send SIGKILL to all processes Sync - send remianing data buffers to disk Unmount - remount all filesystems read-only reBoot - finally a reboot |
And the way i remember this is BUSIER backwards.
Leave a Reply
You must be logged in to post a comment.