There are two ways to do this I currently use.
A) Use Crontab in conjuction with @reboot (I use this to run a command as a specific user because each user gets a crontab)
B) Edit /etc/rc.local (The purpose of rc.local is to run commands at boot, but they are run as root user)
1st make sure /etc/rc.local has correct permissions (I think it is purposely set to not executable by default)
It should look like:
To set permissions:
Make the bottom look like this:
And make sure not to delete the notes(#'s), especially the "shebang"!
Now just put script/scripts into
To test use:
RCLocal Long Prep CMD:
Now you can just edit /root/.reboot.sh whenever and reboot and it should work.