I've currently developed an addon for a popular billing system which i plan to give out to many other people, I would like to make it very easy for them to upgrade the addon whenever i create any bug fixes or updates.
The script uses PHP and MySQL db, i know how to update the MySQL but i'm looking for someone to point me in the right direction on how i could create a PHP script or code that would download the update file or tarball from my website and then upgrade/replace the current file with the new one, that's it.
My concern is just with customers who may be using it on a shared hosting environment or something where they may have problems with upgrades.
I was thinking something sorta along the lines of how Wordpress upgrades itself, i thought about the FTP option but i don't want to make the customers have to enter FTP credentials.