Laptop screen brightness control script

bin/laptop-screen-brightness

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+# Keys: XF86MonBrightnessUp, XF86MonBrightnessDown
+
+class=intel_backlight
+dir=/sys/class/backlight/$class
+cur=$(cat $dir/brightness)
+max=$(cat $dir/max_brightness)
+
+step=$(("$2" + 0))
+cur_pct=$((100 * $cur / $max))
+
+case "$1" in
+	"up")
+		echo "up $2%"
+		target_pct=$(($cur_pct + $2))
+		;;
+	"down")
+		echo "down $2%"
+		target_pct=$(($cur_pct - $2))
+		;;
+	*)
+		echo "Backlight at $cur/$max ($cur_pct%)"
+		exit 0
+esac
+
+if [ "$target_pct" -lt "0" ]; then
+	target_pct=0
+fi
+if [ "$target_pct" -gt "100" ]; then
+	target_pct=100
+fi
+
+target_val=$(($max * $target_pct / 100))
+
+echo "Backlight at $cur/$max ($cur_pct%)"
+echo "Target $target_val ($target_pct%)"
+echo "Dest $dir/brightness"
+echo $target_val > $dir/brightness
+