WARNING: there is an unexpected problem with this. I still have scripts that Kill and start stuff. Those scripts where not killing this proc. So When i kill ES this thing goes and launches another ES,etc. In fact I just telnetted in and the is no way to kill the autostart.sh. For this reason it's not worth it. OK the following works. If it's kill it comes back with retcode 143. $? always has ret code of last command.
Location
/opt/retropie/configs/all/autostart.sh
OR
\\centipede\configs\all\autostart.sh
Recommend edit in nano to keep execute perms on file.