How can I set up Ubuntu Server 16.04 to load a GUI on demand?

Question

I would like my server to boot to command line by default but load a GUI when I need one.

I have a virtual machine set up just for testing and I got the standard UNITY GUI installed on it no problem. I also modified the /etc/default/grub file to boot to text mode. It wasn't working at first and would still boot to the GUI by default but after some research I found that disabling lightdm got me back to the normal terminal login. My issue is I can not launch back into the full GUI anymore. I can use the command 'startx' to launch into a pretty much featureless GUI but that doesn't really help me.

Answer 1

Run systemctl start lightdm to start lightdm, and by extension, the rest of the gui, when you desire. systemctl stop lightdm will shut it down.

Answer 2

Take control from the graphical login manager, use following commands:-

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

edit /etc/default/grub and change

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" 

to

GRUB_CMDLINE_LINUX_DEFAULT="text"

Then, update the grub, by following command :-

sudo update-grub

After reboot login prompt will appear instead of GNOME login terminal

To start GUI use following command :-

sudo systemctl start lightdm.service && sudo gnome-session