BSD's date(1) vs GNU date(1) is one of the problem areas I hit
when building burrow and trying to keep it portable. It's
relatively straight forward if you look at its options, but the
way it parses dates is wildly different from GNU. There's more
different than the same, honestl from GNU. There's more different
than the same, honestly.

How do people work around this normally? Do portable scripts just
avoid using date(1)?