I read about the virtual terminals a little and that gave me an idea. I searched for a way to have two X sessions simultaneously.
I had a look at these sites :
1. How to run multiple user X sessions on the same computer, at the same time?
2. How to drag windows between 2 X servers?
I tried startx -- :1
but my earlier terminal (on Ctrl+Alt+F7) hung up. How do I ensure this does not happen?
My main need is to get Unity on :0
and Gnome-shell on :1
and switch between them like workspaces.
If possible, I'd like to get login screen on tty8 or get option of logging into a different account.
As per question 2, exchanging windows between sessions is not recommended as it is not easy. But if it is possible I'd like to know.
I have Ubuntu 12.04 64bit.
The above command made both sessions crashed (virtual one worked for 15 min then crashed when I switched to real).
Also, how to revert to one X session if system gets overloaded?
Update :
Tried code in answer 3 times but system never stabilizes. Either tty7 or tty8 works, but not simultaneously, for sometime before crashing.