andreasgruener/Script to remove homie devices from mosquitto MQTT

## Script to remove homie devices from mosquitto MQTT
#!/bin/bash
#
# Remove Homie Device from MQTT
#
# Simple Script to remove all reatined messages for a homie device, effectively removing the device from MQTT.
# The script get all topics "below" a device e.g homie/a020a615f72c/$mac and
# send a NULL message with mosquitto_pub to the topic. This removes the retained
# message and the topic will not show up anymore.
#
# How?
# mosquitto_pub -r -n --> sends an empty retained message, which clears the retained message and therefor the topic
#
# Example:
# $ ./clear-retained-messags.sh a020a615f72c
#
# Clearing for device a020a615f72c all messages, last clean will block kill with Ctrl+C when nothing happens anymore.
#
# STARTING :: Checking for valid topics one after the other....
#  0 Checking for Topic ....
#    homie/a020a615f72c/$homie >> sending empty payload to topic with retained flag
#  1 Checking for Topic ....
#    homie/a020a615f72c/$mac >> sending empty payload to topic with retained flag
#  2 Checking for Topic ....
#    homie/a020a615f72c/$name >> sending empty payload to topic with retained flag
#  3 Checking for Topic ....
#    homie/a020a615f72c/$localip >> sending empty payload to topic with retained flag
#
echo
echo "Clearing for device $1 all messages, last clean will block kill with Ctrl+C when nothing happens anymore."
echo
#mosquitto_sub -v -h 10.0.2.2 -t "homie/$1/#" -C $2
echo "STARTING :: Checking for valid topics one after the other...."

# will stop after 100 topics
MAX_TOPICS_TO_CHECK=100

for c in `seq 0 $MAX_TOPICS_TO_CHECK`
    do
    echo "  $c Checking for Topic ...."
    for i in `mosquitto_sub -v -h 10.0.2.2 -t "homie/$1/#" -C 1|cut -d' ' -f1`
        do
            # echo "mosquitto_pub -h 10.0.2.2 -r -n -t \"`echo $i | sed s#'\\$'#'\\\\\\\$'#g`\""
            echo "    $i >> sending empty payload to topic with retained flag"
            mosquitto_pub -h 10.0.2.2 -r -n -t "`echo $i | sed s#'\\$'#'\\\$'#g`"
        done
done