how brain dead is AIX?

[Guy Harris]

>	Actually, what you get is a POSIX line discipline and a BSD line
>discipline, although almost the entire BSD line discipline was duplicated in
>the POSIX (default) line discipline, so unless you're using a Hazeltine 
>terminal with no '~', you'll probably never notice.  Also, be aware that in
>4.4 (or whatever it will be called), CSRG has said that they will be shipping
>a POSIX-compliant line discipline, and will be deprecating the BSD line
>discipline.  I believe Sun is already shipping a POSIX line discipline in
>SunOS.

Sun is shipping a POSIX-compliant "line discipline" streams module in
SunOS 4.1; 4.0[.x] had one that was almost POSIX (IEXTEN was missing,
because that part of the POSIX spec was still Under Construction at the
time 4.0 was being done).

It doesn't have a BSD "line discipline"; instead, it has another streams
module that intercepts V7-style and BSD-style "ioctl"s and maps them
into the extended S5/POSIX "ioctl"s supported by the aforementioned
streams module.

The extensions were based on a POSIX draft (the stuff was sliced out
later, because the Berklish extensions in question were user-interface
extensions; some S5isms were sliced out for the same reason, but, alas,
snuck back in); does the AIX 3.0 POSIX line discipline provide the same
extensions, or is it *sui generis*?

I hope it's compatible; the last thing we need is a continuation of the
"multiple tty driver interfaces" headache in UNIX.  S5R4 offers both of
the aforementioned SunOS streams modules as its "tty driver", with
additional extensions such as support for multibyte characters. 
Berkeley basically picked up those extensions for 4.4BSD as well....

The extensions *don't* include the LTILDE bit, so if you have a
Hazeltine terminal with no "~", you lose.