Is there any way to temporarily disable GUI (X server) when booting an Ubuntu 16.04 LTS installation?
There are various guides advising to add text option onto the line GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub or directly on the linux line in GRUB. These methods work well in Ubuntu 14.04 LTS but I always end up in LightDM when trying them in 16.04 LTS.
1 Answer
To boot Ubuntu 16.04 Desktop without X one time, add systemd.unit=multi-user.target to the linux command line in GRUB.
To make this the default, use
sudo systemctl set-default multi-user.target To return to default booting into X, use
sudo systemctl set-default graphical.target To see the current default target,
sudo systemctl get-default 
