Goduf is a fast duplicate file finder CLI utility.
goduf --help to get the list of available options.
You can download pre-built binaries here, for several platforms/OSes.
Goduf is FLOSS written in Go (Golang).
The source code is available as a Mercurial repository there and a GitHub mirror has been set up.
You can also create a Pull Request on the BitBucket Mercurial mirror.
If you want to install it from source:
% hg clone hg.lilotux.net/golang/mikael/goduf % cd goduf % go build # (or "go install"...)or use the Github mirror:
% go get github.com/McKael/goduf