Originally Posted by s7whitecoral
You mentioned Calibre, how exactly does a program like that work?
Calibre has its own forum here. It has a command line capability as well, but typically you interact with it via its graphical user interface (GUI). Note that this is a cross-platform app, so it might not be very Mac-like in how it does things. This is again something you can try out immediately, it has its own built-in ebook reading capability and one thing to try is converting PDF to MOBI or ePub and seeing how well the conversion does.