On Sat, Jul 23, 2022 at 7:03 AM Dan Cross <crossd@gmail.com> wrote:

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.

An obvious approach, which would leave no real traces in documentation, would be:

$ awk '{print NR, $0}'

A more precise emulation would be more of a pain to type:

$ awk '{printf("%6d\t%s\n", NR, $0)}'

but perfectly usable in a script.