Ubuntu :: Uninstallation Of Packages Not Working?

Someone posted this command in another thread, and I'm wondering how to fully take advantage of it:Code:dpkg -l | grep "^rc" | awk "{print $2}" | xargs sudo apt-get purge -yI presume that this command removes all residual config files, but when I run it, I get messages saying that the packages are not installed, so they can't be removed. How can I remove these configuration files? In my case, the list is about 120 packages long, and I'd really like to free up this space.