So here is my solution:
First I write incoming command to a file called task:
mosquitto_sub -h SERVER -t '/TOPIC/' >> task
then I read the file, and execute the last command:NUMOFLINES=$(wc -l < task) while : do NEWLINE=$(wc -l < task) if [ "$NEWLINE" -gt "$NUMOFLINES" ] then NUMOFLINES=$(wc -l < task) LASTCOMMAND=$(tail -n 1 task) eval ./$LASTCOMMAND fi done
the Message of the topic equals the file name to execute.
This is working just fine for me