A utility that checks if you have an external display and if you're mirroring then turns display brightness to 0 if you are
TurnOffDisplayWhenMirroring
A small utility that checks if you have an external display connected and if you are currently mirroring. If both of these are true, it uses brightness to set your display brightness to 0.
You’ll need to brew install brightness and then symlink that to /usr/local/bin for TurnOffDisplayWhenMirroring to work out of the box.
I’d like to remove the need for brightness, but don’t yet know how to integrate that code into this utility.
I have this set up in Keyboard Maestro to run on login and/or system wake so when I login to my computer, it shuts the built-in display off.
Usage
Turn the display completely off
TurnOffDisplayWhenMirroring 0
Turn the display to full brightness
TurnOffDisplayWhenMirroring 1