I have a Ubuntu 12.10 VM and I do not want the Graphical desktop to boot because it is very heavy. I wish that Ubuntu boot only in text and if I wish, I should be able to start Graphical. Please let me know how I can do it?
The answer revolves arround "runlevels".
You probably want to leave the (default) runlevel at 2, which on most Linux variants is "text only", and modify the graphical environment to only launch on runlevel 3 - then you can change to start graphical by either running X, or better changing to runlevel 3 with the command telinit 3
If you "apt-get install chkconfig", you can list what is running at each runlevel using "chkconfig --list". Level "S" is a special "startup level, and it looks, from my configs, that you will need to turn x11-common off in this level to stop it on boot, and add it to level 3. (You can do this with chkconfig or by fiddling with symlinks in /etc/rc[RUNLEVEL].d