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

Redshift is a handy command-line utility designed to adjust the color temperature of your computer screen based on your environment. This can reduce eye strain and help you maintain healthy sleep patterns, especially if you spend long hours in front of your screen both during the day and at night. Redshift dynamically changes the screen’s color temperature to adapt to varying lighting conditions, taking into account factors such as the time of day and your geographical location.

Use Case 1: Adjust Color Temperature Based on Time of Day

Code:

redshift -t 5700:3600

Motivation:

The human eye is incredibly sensitive to changes in lighting, particularly the blue light emitted by screens. During the day, a higher color temperature around 5700K can mimic natural daylight, providing a neutral and bright tone that’s suitable for productivity. At night, reducing the color temperature to around 3600K introduces a warmer light, which helps minimize blue light exposure and can contribute to better sleep quality by not interfering with the body’s melatonin production.

Explanation:

• -t 5700:3600: This argument sets the target color temperature for day and night. 5700 denotes the color temperature during the day, while 3600 is used at night. This ensures your device’s display adjusts to a comfortable and eye-friendly hue regardless of the time.

Example Output:

Scheduled values: Daytime: 5700K Nighttime: 3600K
Transitioning to daytime settings at brightness 1.0

Use Case 2: Set Custom Location

Code:

redshift -l latitude:longitude

Motivation:

Accurate location settings are vital for Redshift to properly determine sunrise and sunset times, allowing it to adjust your display settings accordingly. By specifying a custom location, users who travel frequently, use a VPN, or live in unconventional timezones can ensure that their screen’s color temperature changes align with the local outdoor environment.

Explanation:

• -l latitude:longitude: This argument takes latitude and longitude as parameters. Providing these values allows Redshift to calculate the precise timing for dawn and dusk based on your geographical position, leading to accurate screen adjustments.

Example Output:

Using location: Latitude 12.34, Longitude 56.78
Solar elevation angle: -6 degrees

Use Case 3: Adjust Screen Brightness Based on Time of Day

Code:

redshift -b 0.7:0.4

Motivation:

Screen brightness can have a substantial impact on comfort and visual appeal. During daytime, users may require higher brightness levels (e.g., 70%) to counteract ambient light. Conversely, lower brightness (e.g., 40%) at night reduces glare, which can prevent eye strain and help maintain a more conducive sleep atmosphere.

Explanation:

• -b 0.7:0.4: This argument sets the screen brightness level for day and night. A brightness level of 0.7 means 70% brightness during the day, while 0.4 represents 40% brightness at night. This helps achieve optimal display settings according to ambient lighting conditions.

Example Output:

Brightness has been set: Daytime: 70% Nighttime: 40%

Use Case 4: Set Custom Gamma Levels

Code:

redshift -g red:green:blue

Motivation:

Gamma correction helps manage the luminance of colors on your screen. By customizing gamma levels, users can adjust how colors are displayed—a crucial feature for graphic designers, photographers, or anyone who deals with visual media. Each color channel (red, green, blue) can be individually modified to achieve the desired color balance.

Explanation:

• -g red:green:blue: This argument specifies gamma levels for each color channel. By setting these values between 0 and 1, users can fine-tune the intensity and contrast of colors on their display, tailoring them to personal preference or professional requirements.

Example Output:

Custom gamma levels set: Red 0.9, Green 0.7, Blue 0.8

Use Case 5: Purge Temperature Changes and Set Constant Temperature

Code:

redshift -PO temperature

Motivation:

Occasionally, you might want to eliminate any dynamic temperature adjustments and maintain a single, consistent color temperature. This mode might be preferable for users who have specific color requirements that must not change, or in scenarios where environmental shifts are negligible, and a constant setting is more practical.

Explanation:

• -P: This option purges any existing dynamic temperature changes and stops any scheduled adjustments.
• -O temperature: This option sets the display to a constant color temperature immediately. This temperature remains unchanged until modified again manually.

Example Output:

One-shot mode activated: Constant temperature set to 5000K

Conclusion:

Redshift is a versatile tool designed to automatically adjust monitor settings in line with the time of day, user location, and specific visual needs. By catering to various use cases such as specifying temperatures, modifying brightness and gamma, and setting a static temperature, Redshift can significantly enhance viewing comfort, reduce eye strain, and help improve sleep quality.