How To Adjust Monitor Brightness From Command Line In Linux

If you’re running Linux and prefer using the command line, adjusting your monitor’s brightness without a GUI is not only possible—it’s often faster and more efficient. Whether you’re scripting your system setup, working on a headless machine, or just like keeping your hands on the keyboard, here’s how to control your screen brightness via the terminal.

Method 1: Using xrandr (for X11 systems)

If you’re running a desktop environment that uses X11 (which many do), xrandr is the go-to tool.

Step 1: Find your display name

Open a terminal and run:

xrandr --current

Look for the connected display—usually something like eDP-1, HDMI-1, or DP-1.

Step 2: Set brightness

Once you have the display name, adjust the brightness (0.0 to 1.0):

xrandr --output eDP-1 --brightness 0.7

This example sets brightness to 70%. Note: this doesn’t change hardware brightness, just software gamma, which may affect video playback and color accuracy.

Method 2: Writing directly to /sys/class/backlight (for hardware-level control)

This method is more reliable on laptops and adjusts actual backlight brightness.

Step 1: Find the backlight device

Run:

ls /sys/class/backlight/

You’ll see a folder like intel_backlight or acpi_video0.

Step 2: Check current and max brightness

cat /sys/class/backlight/intel_backlight/max_brightness
cat /sys/class/backlight/intel_backlight/brightness

Step 3: Set brightness

You need root permissions:

echo 300 | sudo tee /sys/class/backlight/intel_backlight/brightness

Replace 300 with a value between 0 and the max brightness you found earlier.

⚠️ Important: Be careful not to set brightness too low or you might not see your screen at all.

Method 3: Using brightnessctl (more user-friendly)

If you want a safer tool that handles permissions and scales brightness levels automatically:

Step 1: Install it

On Ubuntu/Debian:

sudo apt install brightnessctl

On Arch:

sudo pacman -S brightnessctl

Step 2: Use it

brightnessctl set 50%
brightnessctl set +10%
brightnessctl set 300   # raw value

You can also check current settings with:

brightnessctl

Wrap-Up

Command-line brightness control in Linux gives you flexibility, especially when working with scripts, automation, or minimal setups. Whether you prefer direct control through /sys, a simpler interface like brightnessctl, or quick gamma adjustments with xrandr, there’s a method that fits your needs.

Have questions or want to see how this fits into a script or startup config? Drop a comment below.