Open the Terminal:

You can find Terminal in Applications > Utilities > Terminal, or you can search for it using Spotlight (Command + Space, then type "Terminal"). Disable Automatic Brightness Adjustment:

You can disable automatic brightness adjustments by running this command:

bash sudo defaults write /Library/Preferences/com.apple.iokit.AmbientLightSensor "AutomaticBrightness" -bool false You'll need to enter your administrator password when prompted since this command requires superuser privileges.

Reboot your Mac:

Changes may not take effect until you restart your Mac. To Re-enable Automatic Adjustment:

If you want to turn it back on, you can run:

bash sudo defaults write /Library/Preferences/com.apple.iokit.AmbientLightSensor "AutomaticBrightness" -bool true Using brightness Utility:

If you're looking for a way to control screen brightness via the command line, you can also use a third-party command-line tool called brightness. You can install it using Homebrew:

bash brew install brightness Once installed, you can adjust brightness as follows:

bash brightness 0.5 This command sets the brightness to 50%; you can replace 0.5 with any value between 0 (minimum brightness) and 1 (maximum brightness).