Great idea! ddcutil can communicate with the monitor using the Display Data Channel (DDC) protocol and is often effective for adjusting settings like brightness on external monitors, including Apple Cinema Displays.

Here’s how you can set it up and use it:

1. Install ddcutil

On Arch Linux, install ddcutil from the official repositories:

sudo pacman -S ddcutil

2. Detect Displays

Run the following command to detect available displays and supported features:

ddcutil detect

This should return information about your display, such as model number and supported DDC commands.

3. Adjust Brightness

Once the display is detected, you can adjust the brightness using the following command:

ddcutil setvcp 10 <value>

Here, 10 is the VCP (Virtual Control Panel) code for brightness, and <value> is a number between 0 and 100 (for percentage brightness).

For example, to set brightness to 20%:

ddcutil setvcp 10 20

4. Check Current Brightness

If you want to check the current brightness level:

ddcutil getvcp 10

Troubleshooting

  • You may need to run the ddcutil commands as root (sudo), depending on your system permissions.
  • If the display is not detected, ensure that DDC is enabled on your monitor. Some monitors may require specific cables (e.g., DisplayPort works better than HDMI for DDC).

And not just Apple Cinema! Cool, now I can control all my screens.