I've seen this answer, and it doesn't work. (I've tried the following shortcuts: alt+ctrl+del|Esc|F2|Backspace,I've tried alt+ctrl+R,E,I,S,U,B under normal conditions and the system didn't respond so I doubt it will when the system freezes )

The freeze is apparently caused by Firefox 58.0.1 even though I didn't installed any extension

I'm using Ubuntu 16.04 looking for any shortcut to regain control of the system instead of rebooting every time this occurs (several times a day).

I appreciate your help

Edit: As @Byte Commander have pointed out the shortcut is rather alt+SysRq+R,E,I,S,U,B and it causes a hard reboot, then I'd like instead to have control over the system to issue a kill command to the process causing the freeze.

  • 1
    It's not Alt+Ctrl+R,E,I,S,U,B, but Alt+SysRq+R,E,I,S,U,B - however, this will do an (almost) hard reboot of your system. It's like holding the power button, just that it orders the kernel to flush all disk caches to prevent corrupt file systems.
    – Byte Commander
    Feb 4, 2018 at 21:56
  • @ByteCommander, thank you for the correction. and yes I would wish to find a better alternative that let me just kill the Firefox process or the one causing the freeze. Feb 4, 2018 at 22:16
  • 2
    If your graphical session is frozen you can often switch to a TTY, this can be done with Ctrl+Alt+F1 to F6
    – stumblebee
    Feb 4, 2018 at 23:04
  • 1
    Alt+SysRq+K will kill and restart the GUI without hard booting the system. At least if things are not hung up too badly. IIRC, Ubuntu started disabling most of the magic sysrq keys by default a few releases ago and you have to fiddle with a sysctl variable to turn them back on.
    – psusi
    Feb 5, 2018 at 1:40


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