Misc. 3b1/7300 Questions

[Jim Rosenberg]

In article <7198 at killer.DALLAS.TX.US> wnp at killer.Dallas.TX.US (Wolf Paul) writes:
>3. Is there a way of completely circumventing the user agent, and to
>   start the machine up with, say, 4 windows, all running getty, so 
>   one can log in four times, a la PC6300 or other 286 Unix versions?

**YES**!  This is a somewhat controversial topic up here, so be prepared to get
some divergent opinions.  As long as you are careful to avoid certain gotchas
the screaming prohibitions advertised at the beginning of /etc/inittab not to
edit it can be quite happily thrown in /dev/null.  You *can* edit inittab and
create multiple gettys on /dev/window.  I haven't used the User Agent in so
long I'm not sure I remember how; I normally run with 6 gettys.  Here are the
relevant lines from my inittab:

 vid:2:respawn:/etc/getty window 9600
 v2:2:respawn:/etc/getty window 9600
 v3:2:respawn:/etc/getty window 9600
 v4:2:respawn:/etc/getty window 9600
 v5:2:respawn:/etc/getty window 9600
 v6:2:respawn:/etc/getty window 9600
:v7:2:respawn:/etc/getty window 9600

This gives me my 6 gettys and 7 if I turn on v7, which I don't often do.  You
*WILL* encounter trouble if you tamper with inittab willy-nilly, but I think
the following lists the gotchas:

(1) For a line already in inittab, don't delete it and make sure either ' ' or
dealing with inittab are a disgrace and behave *very* badly in the face of
unexpected formats.  The prohibition against editing inittab is mostly a CYA
maneuver to cover for poorly written programs.

(2) Make sure the new lines you create have either ' ' or ':' in the first
column and that the first field is unique.

(3) ***DO NOT*** put in a getty for an explicit /dev/w?, e.g. /dev/w7.  This
doesn't work.  Each getty should use the *same* device, /dev/window.  An open
on an unused /dev/w? will fail; the driver expects such a device to be opened
by an open on /dev/window.  /dev/window is sort of like /dev/tty for window;
when you open /dev/window it allocates a new window and then opens that
device.

Other than this so long as you adhere to the published format for inittab you
should be all right.

Now for the bad news.  Almost all of UNIX works just fine with multiple
gettys, but there are a few library routines that break.  The main culprit
seems to be getlogin(3C).  Any utility which depends on this routine will
produce flaky results.  If you are addicted to that cute envelope icon to
inform you of new mail you may be unhappy with multiple gettys.  There are a
few other programs that do strange things, but personally I use multiple
gettys every day & have never been sorry.  Note that you will consume a window
for an enabled getty even if you don't have anyone logged in on that window.
Since UA is rather piggy in how many windows it consumes, you may have to
restrict yourself to 3 or 4 gettys if you want to run UA in one of them.

At one time there were allegations that multiple gettys can cause all kinds of
dire consequences, but I was never convinced there was a reason not to enjoy
them.  Perhaps one of you multiple-getty flamers can summarize the ojbections.
-- 
 Jim Rosenberg
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