I’ve recently discovered another useful package for GNU/Linux, Littleutils.
The littleutils include a duplicate file finder (repeats), image optimizers (opt-jpg opt-png opt-gif recomp-jpg), file rename tools (lowercase uppercase), archive recompressors (to-bzip to-7zip to-lzma), a tempfile utility (tempname), all are small programs that do just 1 thing, in a perfect Unix style, so don’t expect anything too complex but these small gems can save you some time to do specific jobs.