My LAMP setup asks for FTP credentials when I try to use the auto update functionality. That’s a pain because I haven’t figured out how to setup FTP on my server yet. Sure it’s just a Google search away, but I would like to get the auto update to work seamlessly.
After setting up suPHP on my web host, auto updates now work on my production sites. So file permissions seem to be the key to the whole problem. The web server user must have write access to the WordPress directory. This post here explains the process WordPress goes through to check if an auto update can be performed successfully. It also provides the simplest solution.
Open a terminal window and type the following command. This assumes that the web server user is www-data. In the case of Ubuntu and Apache on my setup, it is.
sudo chown -R www-data <WordPress folder>
Now when I update plugins automatically, it downloads and applies the update all by itself! Super convenient!