How to Control Screen Brightness on macOS Using the 'brightness' Command (with examples)

The ‘brightness’ command is a powerful utility designed for macOS users to manage the brightness levels of all internal and certain external displays through the command line. This tool allows users to retrieve the current brightness level, set it to a specific value, or adjust the brightness to a predetermined percentage. This capability proves especially useful for users looking to automate display settings or for those who prefer command-line interactions over GUI.

Use Case 1: Show Current Brightness Level

Code:

brightness -l

Motivation:

Knowing the current brightness level of your device’s display can be incredibly helpful, particularly when trying to ensure consistency across multiple screens or when aiming to optimize battery life on portable devices like laptops by managing the luminosity output precisely. This command empowers users to obtain immediate feedback on their display settings without navigating through graphical interfaces.

Explanation:

• brightness: This is the base command that initiates the brightness control function.
• -l: This argument is used to list all the current brightness levels of internal and compatible external displays connected to the system. It stands for ’list,’ enabling users to see the brightness settings as they are currently configured.

Example Output:

display 0: brightness level = 0.736573
display 1: brightness level = 0.844282

Here, the output shows the brightness level for two displays. Display 0 has a brightness level of around 74%, and display 1 is slightly brighter at approximately 84%.

Use Case 2: Set a Specific Brightness Level

Code:

brightness 0.8

Motivation:

Adjusting the brightness to a specific level can cater to personal preferences or environmental conditions where a particular amount of screen brightness is desired. For instance, setting a precise level can enhance productivity in different lighting conditions, aid in reducing eye strain, or save battery life, especially when there is a need to maintain a visual standard across different environments or times of day.

Explanation:

• brightness: Again, this is the primary command used to control the screen brightness.
• 0.8: This is the specific brightness level you want to set, represented as a decimal. The value should range from 0 (completely dark) to 1 (maximum brightness). In this case, 0.8 translates to setting the brightness at 80% of the display’s maximum capability.

Example Output:

The command does not return an output but will adjust the screen’s brightness to 80%. If you run brightness -l afterward, the output will reflect this new setting.

Use Case 3: Set the Brightness to 50%

Code:

brightness 0.5

Motivation:

There are situations where a mid-point brightness is ideal, such as when working indoors with moderate lighting or aiming to preserve battery life during crucial periods without completely dimming the display. This command allows for a quick adjustment to half brightness, offering a balanced approach to screen visibility and power consumption.

Explanation:

• brightness: The essential command to interface with the display’s brightness settings.
• 0.5: This argument signals that the brightness should be set to 50% of the full display capability. This is a convenient benchmark for users seeking a moderate level of screen light, providing enough visibility without being overly bright.

Example Output:

Just like setting a specific brightness, this command will not produce output. However, if subsequent verification using brightness -l is performed, you will see a brightness level of 0.5 for the displays.

Conclusion:

The ‘brightness’ command is a versatile and essential tool for macOS users who wish to control their display’s brightness easily and efficiently via the command line. Whether you’re seeking to check current settings, implement a unique brightness level, or quickly adjust to 50%, the examples given demonstrate the straightforward nature of this utility and its utility in optimizing display settings in various scenarios.