roon-ropieee-mqtt-amp-trigger.sh

#!/bin/sh

# monitor asound status changes and trigger mqtt events

SND_STATUS="/proc/asound/card1/pcm0p/sub0/status"
MQTT_TOPIC="shellies/shelly1-xxxxx/relay/0/command"
MQTT_HOST="mqtt.home"

while true ; do
    value=`cat $SND_STATUS | egrep 'state|closed'`  
    if [[ "$value" =~ "RUNNING" ]] && [[ "$status" != "on" ]] ; then
        status=on
        [[ -t 1 ]] && echo $status 
        # Fire MQTT to turn on amp
        mosquitto_pub -h $MQTT_HOST -t MQTT_TOPIC -m $status

    elif [[ "$value" =~ "closed" ]] && [[ "$status" != "off" ]]; then
        status=off
        [[ -t 1 ]] && echo $status
        # Fire MQTT to turn off amp
        mosquitto_pub -h $MQTT_HOST -t MQTT_TOPIC -m $status
    fi
    sleep 1
done