In .xinitrc, I use
xrandr --output LVDS1 --off
to disable the monitor of my laptop (I always use a projector at school).
But, before I log in with
xinit, or when I temporary go to the console (Linux virtual terminal, for example tty2 with Ctrl+Alt+F2) -- simply put, then the monitor is on, and I'd like it to be off.
I suppose it is logical that it only works during X as xrandr is an X tool. So, I need to find the console "xrandr".