[TUHS] AT+T UNIX PC Information needed

[Sven Mascheck]

Brian S Walden wrote:
> Duncan Anderson asks:

>> Is the lack of streams the main difference between the 2 and 3?
> 
> SVR3 also added shared libraries and RFS. As for TCP/IP the popular
> implementation was from Wollongong.

A slightly awkward [1] but quite comfortable approach to
distinguish the Research/AT&T releases is identifying the shell.

New in the SVR3 shell (features easy to test):
 - "getopts" built-in
 - "read" knows the error message "missing arguments"
(- "cd" diagnostics.  Some vendors modified these again, though.
   Stock SVR3: cd formerly only knew "bad directory" and now there
   are "not a directory", "does not exist", "permission denied" and
   two diagnostics concerning remote file systems.)

[1] Not really awkward, because the introduction of shell functions
    is a quite frequently mentioned feature to identify SVR2.