On Wed, Aug 29, 2018 at 11:58 PM Greg 'groggy' Lehey <grog@lemis.com> wrote:
> I think that Greg is slightly mistaken; `stty` had `-f` documented
> in Net/2 (1991, though of course the entanglements there have been
> discussed), but the option existed in Reno (1990, though it seems to
> be absent from the man page).

No, this is exactly what I suspected, but was too lazy to check up on.
I don't have sources for Tahoe, Reno or Net/2 on my machine, but
FreeBSD 1.0 stty.c has:

  static char sccsid[] = "@(#)stty.c    5.28 (Berkeley) 6/5/91";

And it has the -f flag.  This was (just) before the very first version
of Linux.  My understanding is that FreeBSD 1.0 was primarily derived
from Net/2.  Of course, there's no reason to have chosen that version.

Net/2 was the basis of 386BSD, which begat the patchkits, which begat FreeBSD and NetBSD.

One of the problems with early Linux was that they were just a bunch of guys (and sometimes gals) that had access to these cool unix systems. At the time, there was quite the lag between release by research / university and running in a commercial Unix. So in the early 1990s, there were  a bunch of systems based on 4.2BSD, as well as many based on System V, which lacked the -f flag. At the time, it was at the end of the isolated phase of Unix, where people just made stuff up in relative isolation and when the cross pollination effects of USENET and the first Unix converts having had a decade or so under their belts. The Linux guys weren't old-time Bell Labs guys that would know the differences in detail between the different strains, especially the people that were writing one-off utilities, often to an old, out of date man page, that Linux encouraged to contribute. Nothing wrong with all that, it was a crazy time trying to recreate things at a mile a minute. But some details were not faithfully emulated. It's not surprising: there was always so much to do. So while it existed when they started, it's unlikely the knowledge had diffused enough for them to know about it when it came time to code...