How to Use the 'light' Command for Screen Backlight Control (with examples)

The ’light’ command is a handy tool for managing the backlight of your computer screen through the command line interface. This utility provides users the flexibility to adjust screen brightness with precision and ease. Whether you are in a dimly lit environment or a bright setting, using the ’light’ command allows you to quickly and effortlessly control the intensity of your screen backlight to suit your needs. Below, we will explore several use cases demonstrating how to utilize the ’light’ command effectively.

Use case 1: Get the current backlight value in percent

Code:

light

Motivation:

Understanding the current backlight level of your screen is essential for adjusting your screen brightness effectively. Knowing the percentage value helps users make informed decisions about whether they need to increase or decrease the brightness based on their surroundings. For instance, if you’re aware that your current backlight is at 70%, you may decide to lower it in a darker room to reduce eye strain.

Explanation:

• When you enter the light command without any additional arguments, it retrieves and displays the current backlight level as a percentage. This is a straightforward command aimed at providing immediate information about the brightness settings of your device.

Example Output:

70.00

This output indicates that your screen’s backlight is currently set at 70% of its maximum capacity.

Use case 2: Set the backlight value to 50 percent

Code:

light -S 50

Motivation:

There are situations where you might want to set your backlight to an exact percentage, such as 50%, to achieve a balance between visibility and power consumption. For instance, setting your screen brightness to 50% can be ideal in moderately lit environments where full brightness isn’t necessary, which can also extend battery life in laptops.

Explanation:

• The -S flag: This argument tells the command to “set” the backlight to a specific value immediately.
• 50: This is the percentage value you wish to set the backlight to.

Example Output:

No output is displayed when setting the backlight value. However, you would observe your screen brightness adjusting to the specified level.

Use case 3: Reduce 20 percent from the current backlight value

Code:

light -U 20

Motivation:

There are moments when reducing the brightness incrementally is more appropriate than setting a new value. For example, if you’re transitioning from a bright to a dim room, you might prefer to decrease brightness by 20% gradually. This approach can help minimize strain on your eyes and allow for a more comfortable viewing experience.

Explanation:

• The -U flag: This argument instructs the command to “decrease” the current backlight by a specified percentage.
• 20: The amount in percentage points you wish to decrease the current backlight setting.

Example Output:

Similarly, there is no visible terminal output after executing this command, but you will notice a decrease in the brightness of your screen by 20%.

Use case 4: Add 20 percent to the current backlight value

Code:

light -A 20

Motivation:

In some cases, like moving from indoors to outdoors, you may need to increase your screen’s backlight to improve visibility under brighter lighting conditions. Adding 20% to the current backlight setting provides an easy way to enhance screen readability without going through the effort of manually setting a new target percent.

Explanation:

• The -A flag: This argument signifies the command to “increase” the existing backlight percentage by a specified value.
• 20: The percentage points you wish to add to the current backlight setting.

Example Output:

Again, there won’t be any command-line output, but the screen will visibly brighten as the backlight is increased by 20%.

Conclusion:

The ’light’ command provides a simple yet powerful means of managing screen brightness from the command line. This tool is particularly useful for users who spend extended periods working on computers and need swift control over display settings to maintain comfort and visibility. With the ability to check current settings, set specific brightness levels, or adjust incrementally, the ’light’ command greatly enhances user interaction with their screens in any environment.