text use runlevel
# To remove all the fancy graphics you need to get rid of `splash`.
# Uncomment to disable graphical terminal (grub-pc only)
update-grub and reboot.
But you really only need
GRUB_CMDLINE_LINUX="3". For quick test hit ESC during booting to get into the grub boot menu. Then press e and find the line which specifies kernel and add
3 at the end:
linux /vmlinuz root=/dev/mapper/ubuntu ro 3
Boot it with CTRL+x
Ideally I also want to be able to start GUI by typig a command.
One of these:
$ sudo telinit 5
$ sudo service lightdm restart
$ sudo systemctl start lightdm
Tested on Ubuntu 16.04.1 LTS.