I'm digging around trying to find a Angry Birds save files but File Manager is lying about what's in each folder. How can I give that app su rights? Can I launch it from the command line after typing su or something?
I'm not sure how you'd do that with the built-in file manager, but there are several file managers that will work. I use Root Explorer, and I've heard many other recommend Astro File Manager (which has a free version, I believe). They should work if you have the Superuser app installed (I would assume it comes with CM, but it's in the Market if not).
You cannot grant su to any normal file manager. The application has to "request" su. That is where applications like Root Explorer come in.
AFAIK, Astro File Manager doesn't even make use of su. If it does, some one tell me how because I like that file manager, and will use it for my "root" tasks.