rr -- short for retain and recall -- is a small utility that's both simple and useful. When you need to work on a config file buried deep in the bowels of your system and don't want to type its full path name to do so, rr is just the thing.
To install rr, download the source and decompressed it with a command like
tar xzf rr-1.3.tar.gz. Enter the resulting rr-1.3 subdirectory and run
make and then
sudo make install. The installation includes a man file, so if you need a handy cheat cheat for rr, ask the man.