tty (console): disable monitor

Question

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".

Solution

I don't think that's possible, as the driver(s) used for the virtual consoles are not that flexible. Once the *fb kernel driver is loaded its settings cannot be changed and once the fbcon module is loaded the *fb wouldn't unload (for me).

However, you just want to enable/disable a monitor and not a full equivalent to xrandr on the console, I think. There is the program vbetool which can interact with hardware a little. Depending on your hardware this tool can enable/disable your lcd panel.

The Linux kernel documentation knows a little about this. In Documentation/power/video.txt lists some alternative tools as well.

Comments

[Admin]

Does your laptop's display selecting key (Fn + F2 on my HP Mini 110) do anything?

[Emanuel Berg]

On my F8, it says (in Fn font and color) "CRT/LCD" which sounds as concerning monitors, but nothing happens when I press the keys. It could be that the Fn key is not configured (I never used it, and I have a keyboard configuration based on an external keyboard) -- unless the Fn stuff is completely in the hardware. In either case, I would like it more - like the xrandr solution for X: transparent, and automatically invoked.

[Gilles 'SO- stop being evil']

I'm not sure if that's possible. The console video driver is pretty basic. There's little point in not booting into X nowadays: I recommend booting into xdm/gdm/kdm/….

[Emanuel Berg]

Yes, I'm not going to stop using X. The first command I give is xinit in 95 out of 100 cases. Still, I'd like to examine if it is possible to disable the monitor.

[Emanuel Berg]

100% correct: sudo vbetool dpms off shuts my laptop monitor off, but doesn't affect the projector.

[Emanuel Berg]

@user1129682: Do you know how to make this option default? Or maybe how to always run it before you get to the tty login prompt? I put it in .profile - it works, but requires the super user password each time.

[Emanuel Berg]

@user1129682: Never mind, found it: /etc/rc.local