If you are working in kernel development or device drivers, or running code that could cause your kernel panic, you'll want this tip.

What is the magic?
	The magic SysRq key is a key combination in the Linux kernel which allows 
	the user to perform various low level commands regardless of the system's 
	state using the SysRq key.

	It is often used to recover from freezes, or to reboot a computer without
	corrupting the filesystem.

	The key combination consists of Alt+SysRq+commandkey. In  many systems the
	SysRq key is the printscreen key.

	Before stating this magic, you need to enable the SysRq key.
	echo "1" > /proc/sys/kernel/sysrq

	The above command will enable the sysrq in your system.

What and all can we do?
	As I already told the important keys are Alt+SysRq. Now we will look into the 
	commands.

	k - Kills all the process running on the current virtual console.
	s - This will attempt to sync all the mounted file system
	b - Immediately reboot the system, without unmounting partitions or syncing.
	e - Sends SIGTERM to all process except init.
	m - Output current memory information to the console.
	i - Send the SIGKILL signal to all processes except init
	r - Switch the keyboard from raw mode (the mode used by programs such as X11), 
	    to XLATE mode.
	s - sync all mounted file system.
	t - Output a list of current tasks and their information to the console.
	u - Remount all mounted filesystems in readonly mode

To perform a safe reboot of a Linux computer which hangs up, do the following.

unRaw      (take control of keyboard back from X11,  
 tErminate (send SIGTERM to all processes, allowing them to terminate gracefully),
 kIll      (send SIGILL to all processes, forcing them to terminate immediately), 
  Sync     (flush data to disk),
  Unmount  (remount all filesystems read-only),
reBoot.
	This will avoid the fsck during the next re-booting.