1#!/bin/sh
 2
 3OUTPUT="HDMI-0"
 4STEP=0.1
 5MIN=0.1
 6MAX=1.0
 7
 8case "$1" in
 9    up)
10        current=$(xrandr --verbose | grep -A5 "^$OUTPUT connected" | grep -m1 "Brightness" | awk '{print $2}')
11        [ -z "$current" ] && current=1.0
12        new=$(echo "$current + $STEP" | bc)
13        [ "$(echo "$new > $MAX" | bc)" -eq 1 ] && new=$MAX
14        xrandr --output "$OUTPUT" --brightness "$new"
15        ;;
16    down)
17        current=$(xrandr --verbose | grep -A5 "^$OUTPUT connected" | grep -m1 "Brightness" | awk '{print $2}')
18        [ -z "$current" ] && current=1.0
19        new=$(echo "$current - $STEP" | bc)
20        [ "$(echo "$new < $MIN" | bc)" -eq 1 ] && new=$MIN
21        xrandr --output "$OUTPUT" --brightness "$new"
22        ;;
23    *)
24        echo "usage: $0 {up|down}"
25        exit 1
26        ;;
27esac