TIP-ing from a pty to a hardwired port

[ben ullrich]

I have the following need, and would appreciate any insight on a way to
implement it on a Sun-4 running SunOS 4.0.1 .

I would like to run a process on a terminal port that can be attached to
and detached from at will from any user on the system.  I'm planning to
run a process under a debugger on this port so that anyone who has access
to the host can attach to the terminal port on which the process was
started and work with the debugger.

I have done something similar to this in the past with tip(1) accessing a
rs-232 line to a port running the process: a user tip's onto a port which
is wired via rs-232 to the port where the session of interest is running.
the flow control makes things a bit jumpy, but it was workable, as long as
we had **2** ports available.  i presently only have 2 serial ports on the
machine in question, one of which is dedicated to the console for the
system.  I don't have access to another port on another system that can be
strung to the hosting system of the session of interest.

What i'd like to do is have some tty port on the system be hooked into the
i/o channel that a user logs into and starts up a session with this
program and debugger... something like TIP-ing into a /dev/tty00 that has
a getty or a shell running on it.  i have tried making a /dev entry with
the same device numbers (and a minor device number 128 higher than the
base minor device number, as is done for dialout ports on Sun) as the port
i'd like to use (ttyb), but this doesn't work: I get nothing after getting
connected using tip(1).

It doesn't have to be tip(1) at all; I just want a way of attaching to a
port that has a getty or shell running on it from the same system on which
this port resides.

Thanks for any help.  Please reply via email, as I don't normally read this
newsgroup.

..ben
----
ben ullrich	       consider my words disclaimed,if you consider them at all
sybase, inc., emeryville, ca	"When you deal with human beings, a certain
+1 (415) 596 - 3500	        amount of nonsense is inevitable." -- mike trout
ben at sybase.com			       {pyramid,pacbell,sun,lll-tis}!sybase!ben