How to Disable GUI Boot in Ubuntu 12.04

Following the steps I followed to enable console boot in Ubuntu 12.04
Step 1 First update your repository by running

sudo apt-get update

Step 2 There is some bug in old version of lightdm, so we need to upgrade the same. To do so run,

sudo apt-get install lightdm

Step 3 Now we have to modify grub config.
Step 3a Open /etc/default/grub with your faviourite editor and change

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

GRUB_CMDLINE_LINUX_DEFAULT="text"

Step 3b Also comment GRUB_HIDDEN_TIMEOUT=0 This line is for unhiding the GRUB menu

Step 4 Now we will upgrade GRUB configuration

sudo update-grub

Step 5 Now restart your machine. Voilla you will be in console mode

At any time you need after booting your system you want to change to gui mode the run

startx

If you want to restore Ubuntu’s GUI mode then

Open /etc/default/grub with your faviourite editor and change

GRUB_CMDLINE_LINUX_DEFAULT="text"

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Update GRUB by running

sudo update-grub

That’s it