How to Use the Command 'brightnessctl' (with Examples)

The brightnessctl utility is a versatile tool designed for Linux operating systems, allowing users to effortlessly manage the brightness of their device’s display and other components with adjustable brightness settings. This command line tool offers a streamlined method to both query and modify brightness levels, presenting options to list available devices, check current brightness settings, and adjust these settings up or down as needed.

Use Case 1: List Devices with Changeable Brightness

Code:

brightnessctl --list

Motivation for using the example:

Most modern laptops and desktops come with multiple devices capable of changing brightness, such as the screen backlight, keyboard backlight, or other external displays. Before attempting to manipulate the brightness of any component, it’s essential to identify which devices are available and adjustable. This command provides a comprehensive list, allowing users to understand what devices can have their brightness settings modified, avoiding unnecessary trial and error.

Explanation:

• brightnessctl: This initiates the utility, telling the system that you are about to execute a command related to brightness control.
• --list: This option tells brightnessctl to enumerate all detected devices that support brightness adjustments. It is particularly useful for verifying that the system recognizes these devices and for identifying the correct target for subsequent brightness commands.

Example output:

Available devices:
Device 'intel_backlight' of class 'backlight':
	Supported brightness levels: 0% to 100%
Device 'kbd_backlight' of class 'leds':
	Supported brightness levels: 0% to 100%

Use Case 2: Print the Current Brightness of the Display Backlight

Code:

brightnessctl get

Motivation for using the example:

Tracking the current brightness level is crucial for users who need to recreate ideal lighting conditions or monitor power consumption. Especially in environments where screen glare is a concern, knowing the exact brightness level can help maintain optimal visibility and reduce eye strain.

Explanation:

• brightnessctl: The primary command to access brightness settings.
• get: This option is used to retrieve the current brightness level of the default or specified device. It helps users confirm current settings before making adjustments, ensuring they know their baseline before alterations.

Example output:

Current brightness: 120 (50%)

Use Case 3: Set the Brightness of the Display Backlight to a Specified Percentage Within Range

Code:

brightnessctl set 50%

Motivation for using the example:

Adjusting screen brightness to a specific percentage is a common requirement for users seeking to align their device’s lighting with ambient conditions. This command provides a precise means to set brightness, whether you’re trying to conserve battery life by dimming the screen or enhance visibility by brightening it.

Explanation:

• brightnessctl: Engages the brightness adjustment tool.
• set: Indicates that the subsequent numeric value will be a target brightness level.
• 50%: The desired brightness level, expressed as a percentage of the device’s full range. The system interprets this value, adjusting the brightness proportionally.

Example output:

Setting brightness to 50%...
Brightness set to 50% (120 out of 240)

Use Case 4: Increase Brightness by a Specified Increment

Code:

brightnessctl set +10%

Motivation for using the example:

Incrementing brightness in small, specified amounts allows users to fine-tune their display to accommodate gradual changes in lighting. Whether indoors or outdoors, this command enables users to make subtle adjustments without large or disruptive changes to screen visibility.

Explanation:

• brightnessctl: Calls the brightness control utility.
• set: Signals the toolkit to adjust brightness.
• +10%: Directs the tool to increase the current brightness setting by 10%, allowing for precise local incremental changes.

Example output:

Increasing brightness by 10%...
Brightness increased to 60% (144 out of 240)

Use Case 5: Decrease Brightness by a Specified Decrement

Code:

brightnessctl set 10%-```

Motivation for using the example:

Reducing the brightness by a specific amount is beneficial in conserving energy and reducing eye strain when moving from a brightly lit environment to a dimmer one. This command precisely decreases brightness, helping users maintain comfort without guessing the new brightness level.

Explanation:

- `brightnessctl`: Invokes the command line tool focused on brightness.
- `set`: Indicates an adjustment will follow.
- `10%-`: Commands the tool to decrease the current brightness by 10%, facilitating gradual and controlled reductions in brightness.

Example output:

Decreasing brightness by 10%… Brightness decreased to 50% (120 out of 240)

## Conclusion

The `brightnessctl` utility provides a powerful and flexible set of commands for managing device brightness on Linux operating systems. From listing adjustable devices to fine-tuning brightness levels, these use cases demonstrate its utility in achieving optimal screen lighting conditions tailored to user preferences and environmental contexts. Whether for productivity, comfort, or power conservation, mastering these commands can significantly enhance the Linux user experience.