4 Easy Ways To Get Yourself Out Of a Ubuntu Crash

1. Force quit freeze apps

use System Monitor or kill syntax

2. Restart 'X'

Ctrl + Alt + Backspace

3. MagicSys Keys

Alt + SysRQ + K ... this'll kill all process

4. MagicSys Key Combination

If all the three process failed..

Alt + SysRQ .. and press R, E, I, S, U, B

and this is what R E I S U B means:

R: Switch the keyboard from raw mode to XLATE mode
E: Send the SIGTERM signal to all processes except init
I: Send the SIGKILL signal to all processes except init
S: Sync all mounted filesystems
U: Remount all mounted filesystems in read-only mode
B: Immediately reboot the system, without unmounting partitions or syncing

refs:

http://maketecheasier.com/4-ways-to-get-yourself-out-of-a-ubuntu-crash/2008/09/01

http://tips4linux.com/force-a-clean-reboot-when-the-system-freezes/

add:

crash analysis tool http://magazine.redhat.com/2007/08/15/a-quick-overview-of-linux-kernel-crash-dump-analysis/