Restarting gnome-shell

[Jaimon Jose <jjaimon yahoo com>]

Is there a way I can restart or send a signal to restart gnome-shell
from a terminal?.  I noticed that my gnome-shell freezes or crashes at
times (tried to debug a little bit attaching gdb to gnome-shell. But,
that didn't reveal much) and I don't have a way to restart gome-shell
without restarting my Xsession. (Ctrl+Alt+Bkspc).  Alt+F2+r doesn't work
as gnome-shell itself is unresponsive.  It will be convenient if I can
switch to a console (Ctrl+Alt+F1) and restart or send a signal to 
gnome-shell to restart.

Thanks for your help,
--jaimon