Command-line display brightness control for OS X.
This tool enables programmatic control of OS X screen brightness. You can set and retrieve hardware brightness settings with this utility.
Please note that if you cannot control your display’s brightness from Displays System Preferences, you will not be able to do it with brightness. See #11 for more information and some potential other options.
brew install brightness
git clone https://github.com/nriley/brightness.git
cd brightness
make
sudo make installTwo versions are included. Both require OS X 10.6 or later — but go back in the commit history and you’ll find things compatible with older OS X versions.
brightness.c — what you compile with the instructions above — uses documented APIs. It works on internal laptop displays. It doesn’t work on older Apple external LCDs which connect via DVI and USB. I don’t know if it works on newer external displays, such as Thunderbolt displays, because I don’t have any to test with. (Feedback welcome.)
brightness.m uses SPIs reverse-engineered from Displays System Preferences as of 2005. It does not work as of OS X 10.9, always returning 0 brightness, but does work on Mac OS X 10.6. (I do not have any plans to update it nor any hardware with which to test, but contributions are welcome.) Compilation instructions are in a comment at the top of the file.
Set 100% brightness: brightness 1
Set 50% brightness: brightness 0.5
Show current brightness: brightness -l
% brightness
usage: brightness [-m|-d display] [-v] <brightness>
or: brightness -l [-v]
% brightness -lv
display 0: main, active, awake, online, built-in, ID 0x4280a80
resolution 1680 x 1050 pt (3360 x 2100 px) @ 0.0 Hz, origin (0, 0)
physical size 286 x 179 mm
IOKit flags 0x400003; IOKit display mode ID 0x80001002
usable for desktop GUI, uses OpenGL acceleration
display 0: brightness 0.690430
% brightness -m 0.6
% brightness -l
display 0: main, active, awake, online, built-in, ID 0x4280a80
display 0: brightness 0.599609