Forcing grub menu to external monitor connected to laptop via HDMI/VGA

Question

Is there any way to force grub menu to show it's content in external monitor (for selecting the os to boot on win or ubuntu), I use my laptop more like a desktop with a monitor connected to it because of broken laptop fan socket. Either HDMI or VGA would work.

Answer 1

Here is a bad way to do this, for most, that may just be good for you.

On desktop, open this file as root

gksu gedit  /etc/default/grub

and find this line

GRUB_CMDLINE_LINUX_DEFAULT=...

and add a this to the end

video=LVDS-1:d

my whole line is

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

so I would add it here

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=LVDS-1:d"

Change lvds-1 for you monitors name, if it is different, find it with

xrandr -q

Save and exit, and run the command

sudo update-grub

This will disable the Laptop display for both grub and the desktop and force it to the external display, even if you remove the HDMI cable, the laptop screen will not work. You can remove the change to change it back to using the laptop screen.

I can't test this as I don't have a laptop, but I took it from an question at arch, where the issue was no laptop display after forcing grub to an external monitor.

I don't recommend this for most users who want there laptop to still be portable.

Answer 2

At the risk of sounding overly simplistic, I learned, through a bit of experimentation, that hardware engineers are aware of the issue and have responded. On my old but trusty Toshiba Satellite S55 laptop (from 2013), the monitor at boot can be selected or left up to auto-select. In auto-select mode (the default), the computer will activate an external monitor if the lid is closed on the laptop. I just tried it and it works! Definitely worth a try, but check your hardware boot settings, YMMV.