The unrar pacakge is available from rpmfusion-nonfree repos. If you install them (info at rpmfusion.org), and then do yum install unrar you should have it.
Once you do, then it's
unrar e <directory of rars>. For example, if the directory has a bunch of rar files 001.rar 002.rar and so on and is called rardirectory
unrar e rardirectory/001.rar
This will unrar all the rar files in order to give you the complete file. Otherw rar archives will have a rar file just called whatever.rar (as opposed to having a number).
On CentOS, you must type it as shown above, unrar e (in other words, no dash before the e). I believe in Fedora you can either do unrar e or unrar -e.
---------- Post added at 05:22 PM CDT ---------- Previous post was at 05:22 PM CDT ----------
Heh looks like we all began posting at the same time.