Same i/o on two terminals?

[Steven L Wootton]

Say I log in to my account from two different physical terminals.  Each
login process gets its own /dev/tty* (of course).  I'll call them terminals
A and B (so I won't confuse myself).

Is there any way that I use terminal B to control the process running on
terminal A?  That is, can I get the same i/o on both screens at the same
time?  The implication here is that I want the same characters to echo on
each terminal.

I can see why this might be a "bad thing" from a security standpoint, but I
can't see why this should be an issue if I only do this from one of my
logins to another.

My site specialist didn't have any information on this.

The systems I use most include a Gould NP1 (4.2 BSD), an HP 9000/300 (HP-UX
[SVR3]), and an Amdahl of some sort (UTS [SVR3]).

Any shell scripts, C code fragments, RTFM pointers, or explanations as to
why this is impossible are appreciated.  Email is fine as well.  Thanks.

Steve Wootton
stevew@{en,ei,el}.ecn.purdue.edu
stevew at pur-ee.uucp
stevew%ecn.purdue.edu at purccvm.bitnet