OK, first of all you need to install the gnome media apps:
yum install gnome-media-apps
This provides a command line tool called sox.
You can just tell sox to convert a file from .ogg to .mp3 like this:
sox audio.ogg audio.mp3
It didnt work! I’m getting a horrible error!
If you are seeing something that says:
sox FAIL formats: no handler for file extension `mp3'
Then fear not.
Install the required plugin:
yum install sox-plugins-freeworld
And it should all work as intended. There you go – super easy conversion from .ogg to .mp3.