Edit /etc/default/grub with your favourite editor, e.g. nano:

sudo nano /etc/default/grub

Find this line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Change it to:

GRUB_CMDLINE_LINUX_DEFAULT="text"

Update GRUB:

sudo update-grub

For systems that use systemd

^{This is an additional step for systemd releases, e.g. Ubuntu 15.04, the steps above for grub are still necessary.}

You need to tell systemd to not load the graphical login manager:

sudo systemctl enable multi-user.target --force
sudo systemctl set-default multi-user.target

You will still be able to use X by typing startx after you logged in.

Installing the GUI will probably cause it to start automatically, but it's very easy to boot to text mode in Ubuntu. Just open /etc/default/grub as root and add text to the

GRUB_CMDLINE_LINUX_DEFAULT=

line. Then run:

sudo update-grub

Your system will then always boot to text mode.

If you want to boot to the GUI, just press e in the boot menu and remove text from the kernel line.

If you want to start the GUI after boot, just run:

sudo /etc/init.d/lightdm start

Hope this helps :)

For 11.04 and previous versions (and perhaps later)

If you want to boot into text mode:

Edit /etc/default/grub. For example:

sudo gedit /etc/default/grub

Find this line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Add text:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash text"

Then update Grub:

sudo update-grub

Note: Removing quiet splash (i.e. GRUB_CMDLINE_LINUX_DEFAULT="") will show text during boot but then show a graphical login screen as usual. Replacing quiet splash with text will leave you at a login prompt; to start a GNOME session, use sudo /etc/init.d/gdm start or startx.

To disable GDM:
Install bum .

After installation it will be found under System>>Administration>>Bootup-Manager

Uncheck Gnome Display Manager

If you are using lightdm as a login manager it can be prevented from loading by disabling it.

You can use an override:

sudo bash -c 'echo "manual" >> /etc/init/lightdm.override'

And to start lightdm on command:

sudo start lightdm

To restore your system so that lightdm is always started on boot:

sudo rm /etc/init/lightdm.override

For more information, the upstart cookbook is your friend:

• http://upstart.ubuntu.com/cookbook/

You could use Ubuntu Server edition.

It has already beed answered in several old questions, but cannot find them just now, so I sum up the various situations here.

1. To stop an X server started by startx, simply terminate the session.

2. To stop an X server started by the Login Manager (GDM), run

   sudo service gdm stop
   

   then move to a tty, for example pressing Ctrl-Alt-F1, then login here in text mode.

3. To avoid at all the starting of the Login Manager (and X), modify

   /etc/default/grub
   

   changing the line

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
   

   to become

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash text"
   

   then update the grub configuration file with

   sudo update-grub
   

   so that the next time you go directly to text mode, and you need startx to initiate a X session, or alternatively sudo service gdm start.

I did following

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 favourite 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 un-hiding the GRUB menu

Step 4 Now we will upgrade GRUB configuration

sudo update-grub

Step 5 Ubuntu 11.10 Desktop edition use lightdm for GUI. We need to disable the same

sudo update-rc.d -f lightdm remove

Step 6 Now restart your machine.

Found at Disable GUI Boot in Ubuntu 11.10

Yes, telling the system to start in console at boot time is possible through editing grub command. When you reach grub menu, highlight Ubuntu's entry and press e.

You will see text such as in the image bellow:

Change the text quiet splash to text . Press F10 to launch. (Source: rolling-ubuntu). I have tested this on my system, 14.04, booted into text console, no lightdm in sight. Started lightdm with sudo initctl start lightdm

To avoid doing so every time, you can add permanent grub entry with such option as suggested in this answer

An alternative suggestion, is to change default runlevel and change runlevels at which lightdm starts/stops, as suggested by another answer on the same post

I noticed this thread revolves around assuming you are using LightDM as the Display Manager. Though this may be the usual DM/welcomer, that isn't part of the original question. (And he did not specify..)

In my case:

I use KDE/KDM on my server. Instead, I simply disable the upstart/service from starting under runlevel 2:

/etc/init/kdm.conf: (kdm: 4:4.8.5-0ubuntu0.3 , Upstart Version: 1.5-0ubuntu7.2)

Find:

start on ((filesystem

change

           and runlevel [!06]

to

           and runlevel [!026]

Assuming your default runlevel is 2 on fresh reboot, you will have a console and not KDM. Then you can run DM/DE manually when needed = Use 'startx' /etc. To return machine to console and exit X server completely after this, just use 'log out'.

Other dm .confs scripts are similar. (I setup my server like this.. to be able to work using a GUI occasionally - but, not pull resources when not using/needed or simply rebooting.)

EDIT

(My current system: Upstart 1.12.1 / Ubuntu 14.04)

Due to upstart the way to resolve this lately is to simply disable your Display Manager from starting on boot:

echo "manual" | sudo tee -a /etc/init/{service}.override

For lightdm:

 echo  "manual" | sudo tee -a /etc/init/lightdm.override

This can be any service in /etc/init including kdm/gdm. 'startx' to run as needed following a reboot.

ref:
How to disable lightdm?
How to enable or disable services?

I did following:

1. First update your repository by running

   sudo apt-get update
   

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
   

3. Now we have to modify grub config.

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

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
   

   to

   GRUB_CMDLINE_LINUX_DEFAULT="text"
   

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

4. Now we will upgrade GRUB configuration

   sudo update-grub
   

5. Now restart your machine.