TODO

rdup:
    update manpage

rdup-tr:
    with tar/pax output hardlinks must come last
    update manpage

rdup-up:
    update manpage

tests:
    tweak almost correct input and let rdup crash

    autom. tests...?
    for i in $(seq 0 100); do make check 2>/dev/null | grep '^# of expected'; sleep 1; done
