Some time ago I used cron to do just that. You can make an entry like this
@reboot /path/to/my/script
The path to my script will be the path to your appstart.sh file.
So you open your terminal.
You type in crontab -e
(this will open a file in your default editor, problably nano)
You scroll down and on the bottom of the file you type @reboot /path/to/file
Then you save and exit.