Waybar DDC/CI brightness control script

README.md

Control external monitor brightness using ddcutil with Waybar integration.

Features

• Left click: Set brightness to 100%
• Right click: Set brightness to 0%
• Scroll: Fine adjustment (optional)
• Instant updates via signals

Requirements

• ddcutil installed

Usage

• Make sure to make the script executable!
• chmod +x brightness-control.sh

Waybar config

  "custom/brightness": {
    "format": "☀ {}%",
    "interval": "once",
    "signal": 9,
    "exec": "~/.config/waybar/scripts/brightness.sh get",
    "on-scroll-up": "~/.config/waybar/scripts/brightness.sh up",
    "on-scroll-down": "~/.config/waybar/scripts/brightness.sh down",
    "on-click": "~/.config/waybar/scripts/brightness.sh left_click",
    "on-click-right": "~/.config/waybar/scripts/brightness.sh right_click",
  },

brightness-control.sh

#!/bin/bash

# --- CONFIGURATION ---
DISPLAY_NUM=1
STEP=5
STATE_FILE="/tmp/waybar_brightness.tmp"
# ---------------------

# Function to send the actual DDC/CI command in the background
set_brightness_in_background() {
    pkill -f "ddcutil.*setvcp 10"
    (ddcutil --display $DISPLAY_NUM setvcp 10 $1) &
}

# Ensure state file exists, or create it by querying the monitor
if [ ! -f "$STATE_FILE" ]; then
    # ddcutil terse output format: "VCP 10 C <current> <max>"
    initial_brightness=$(ddcutil --display $DISPLAY_NUM getvcp 10 -t 2>/dev/null | awk '{print $4}')
    # Fallback to 50 if ddcutil fails or returns non-numeric
    if ! [[ "$initial_brightness" =~ ^[0-9]+$ ]]; then
        initial_brightness=50
    fi
    echo "$initial_brightness" > "$STATE_FILE"
fi

current=$(cat "$STATE_FILE")
# Validate current is a number, fallback to 50 if corrupted
if ! [[ "$current" =~ ^[0-9]+$ ]]; then
    current=50
    echo "$current" > "$STATE_FILE"
fi

case "$1" in
    "get")
        echo "$current"
        ;;
    "up")
        new_brightness=$((current + STEP > 100 ? 100 : current + STEP))
        if [ "$current" -ne "$new_brightness" ]; then
            echo "$new_brightness" > "$STATE_FILE"
            set_brightness_in_background "$new_brightness"
        fi
        pkill -RTMIN+9 waybar # Can add whatever RTMIN+n you please, as long as it's an integer. Make sure the signals match between the config and script.
        ;;
    "down")
        new_brightness=$((current - STEP < 0 ? 0 : current - STEP))
        if [ "$current" -ne "$new_brightness" ]; then
            echo "$new_brightness" > "$STATE_FILE"
            set_brightness_in_background "$new_brightness"
        fi
        pkill -RTMIN+9 waybar
        ;;
    "right_click")
	new_brightness=0
	if [ "$current" -ne "$new_brightness" ]; then
            echo "$new_brightness" > "$STATE_FILE"
            set_brightness_in_background "$new_brightness"
        fi
        pkill -RTMIN+9 waybar
        ;;
    "left_click")
	new_brightness=100
     	if [ "$current" -ne "$new_brightness" ]; then
            echo "$new_brightness" > "$STATE_FILE"
            set_brightness_in_background "$new_brightness"
        fi
        pkill -RTMIN+9 waybar
        ;;
esac

brightness.sh: line 37: [: : integer expected
error when srolling down. likewise for the rest of the commands
What do i need to fix. (I have ddcutil installed, made it executable)

brightness.sh: line 37: [: : integer expected error when srolling down. likewise for the rest of the commands What do i need to fix. (I have ddcutil installed, made it executable)

Hello, sorry for the long wait. I updated it. I was initially an idiot and used the wrong awk regex. there was no value parameter. it should work now, tested it personally on my pc. I also changed the signal from +8 to +9 due to a conflict with my current omarchy setup.