The next time that happens, try running the command again, but prepend a 'g' (so gsed, gawk, etc). Most BSD systems have the GNU versions of utilities present in their ports systems, and many come with the gnu coreutils installed, g-prefixed.
None of them come with the GNU coreutils installed. You have to install them if you want them. I'd recommend learning basic unix commands instead though, it doesn't take very long at all.
