Homebridge disk space as Lightbulb with homebridge-cmd4 plugin

DiskSpaceLightbulb.sh

#!/usr/bin/env bash

# Plugin: https://github.com/ztalbot2000/homebridge-cmd4
#
# config.json
#
#  ...
#  {
#     "platform": "Cmd4",
#     "name": "Cmd4",
#     "accessories":
#     [
#         {
#           "type": "Lightbulb",
#           "name": "Disk Space",
#           "brightness":100,
#           "polling": true,
#           "interval": 5,
#           "stateChangeResponseTime": 0,
#           "state_cmd": "bash .homebridge/Cmd4Scripts/DiskSpaceLightbulb.sh"
#         }
#     ]
#  }
#  ...

if [ "$1" = "Get" ]; then
    if [ "$3" == "On" ]; then
        echo 1
        exit 0
    elif [ "$3" == "Brightness" ]; then
        diskSpace=$(df -Bm | sed '2q;d' | sed 's/.*\([0-9][0-9]\%\).*/\1/' | sed s/\%//)
        echo "$diskSpace"
        exit 0
    fi
fi

if [ "$1" = "Set" ]; then
    echo 1
    exit 0
fi

exit -1