On Sat, Jul 23, 2022, 3:56 AM segaloco via TUHS <tuhs@tuhs.org> wrote:

> [snip]
> So all in all, num was an attempt that petered out, but # stayed in ex.
> System III and 4.4BSD-Lite ed derivatives implement n, and nl was
> introduced in System III for the AT&T line and slowly cropped up
> elsewhere.  System V picked up ex in 1982, allowing nl, ed with n, and ex
> with # in the AT&T line.  GNU had one out of the gate when POSIX hit.  BSDs
> were late to the party with regards to both ed with n as well as nl, with
> nl only being adopted after the last Berkeley releases and subsequent
> fracturing.
>

It may be worth noting that BSD had `cat -n` in 4BSD by October, 1980:
https://minnie.tuhs.org/cgi-bin/utree.pl?file=4BSD/usr/man/man1/cat.1

That may explain the relatively late incorporation of `nl` in, at least,
the BSD lineage.

        - Dan C.