pi@retropie:~ $ sudo nano /etc/rc.local

  GNU nano 2.2.6            File: /etc/rc.local

#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
  printf "My IP address is %s\n" "$_IP"
fi

sudo python3 /opt/RetroFlag/SafeShutdown.py &
dmesg --console-off
exit 0