@ledoian @piggo Which isn't surprising given that the paste(1) and join(1) manpages from GNU are horribly incomplete.
Which is yet another reason why I have man-pages-posix on most of my client machines, see https://manned.org/join.1p and https://manned.org/paste.1p for example.
But looking at it again, I think rsync(1) manpage is pretty good, even provides some examples right from the start.