Turn off the backlight of an external monitor

Is there a command-line way to turn off the backlight of an external monitor connected to laptop through HDMI?

This works on laptop’s monitor:

echo 10 | sudo tee '/sys/devices/pci0000:00/0000:00:01.0/0000:02:00.0/drm/card0/card0-LVDS-1/nv_backlight/brightness'

But I couldn’t find something like this for the external monitor.

Using xbacklight doesn’t work on both laptop’s monitor and external monitor (and I don’t even know if it could turn off the backlight).

Also I’m aware of xrandr --output HDMI-1 --brightness 0 and xrandr --output HDMI-1 --off but the first one still leaves the mouse cursor visible (maybe find some way to hide it?), and the second one completely turns off the monitor, which I don’t want.

Asked By: MichalH

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Ok I found a solution, not exactly what I was hoping for, but it works.

Install unclutter and use

unclutter -idle 0 -root -jitter 9999

This hides your mouse.

So the final approach is:

xrandr --output HDMI-1 --brightness 0
unclutter -idle 0 -root -jitter 9999
Answered By: MichalH