Running a systemd service as a user other than root!

Use systemd:

To show the problem use journalctl -xe after you started the service.

You don't need a bash script, put this in your service file:

ExecStart=/usr/share/amos/run_amos.sh

There is no need for ExecStop, systemd will stop all child processes. You can view the output with journalctl -u amos.service.

I think you want forking instead of simple. Simple assumes your process doesn't exit, so when it does, it calls the process dead.

You probably want to remove the amos_service.sh script and put it's functionality into the amos.service.