Running a bash script on system start can be an involved process, depending on you distro. The proper way is to create a system service and plug it into /init.d but you can leverage the crontab if you want a simple quick way to run something on startup.
How to run a script on start up/reboot
cd return to user home
vim startup.sh create script
chmod +x startup.sh Make script executable
crontab -e Edit crontab
Add the line
@reboot sh $HOME/startup.sh
Now your script will run on reboot.
Source Stack overflow thread