I installed Ubuntu on to a laptop which has since been repurposed to be a family server. I disabled lightdm at startup by deleting
/etc/init/lightdm.conf, since running an X server is a waste of resources I could otherwise put to a more server-y use (like filesystem cache or running some more virtual machines). However, this means that the laptop's built-in display is constantly left on, with plymouth animating its start-up animation, which burns a surprising amount of CPU and heats up the machine (since the display's backlight is on).
Switching to a virtual console works, but it still leaves plymouth running and leaves the monitor running.
Is there a way to tell plymouth that it's done, and that the display should sleep?