i have to close and open the lid to adjust brightness mac

If you want a command line solution, I found brightness.c which compiled cleanly using: gcc -std=c99 -o brightness brightness.c -framework IOKit -framework ApplicationServices You can adjust each monitor separately, and set keyboard shortcuts for them as well. One of my favorite tools for doing this is Shades which is 'donationware.' Lunar is not restricted to any specific display type or connection method, so it should work with most displays connected over USB-C, Thunberbolt, etc.

It also supports tweaking of brightness and contrast ranges/offsets to get exactly the desired levels. With Lunar, you can use the standard display controls (and keyboard keys!) to adjust the brightness simultaneously on the main and external display, which is exactly what I wanted. Lunar is an app which allows you to automatically sync the system display brightness with the brightness of an external monitor.

If you're using a MacBook with Touch Bar, this works for the 'brighter'/'less bright' Touch Bar buttons but NOT for the Touch Bar brightness slider.

Important note: You have to plug in the USB cable from the Display to the Macbook Pro in order that the keyboard shortcuts work. I have tested this on my MacBook Air 2011 13' and 27' Thunderbolt Display. On Apple displays, if you press Control- F1 or Control- F2 the brightness on a secondary display will adjust.

I have to close and open the lid to adjust brightness mac