attaching a terminal to 'join' another?

[Dan Nelson]

In the last episode (Aug 02), Jim Stapleton said:
> Sorry if my question is a bit confusing - I'm not even sure the
> proper terminology, so I don't know what the best way to start
> looking is.
> 
> I'm rebuilding a system at home, and I'd like to check how the build
> is going at a slow time at work sometimes. I can connect to the
> system from work (ssh into my main box, and then from there, ssh to
> the system I'm working on). I have a terminal opened on that system
> (actually, another ssh session fron the main box), and I'd like to
> have my new connection attach to that terminal session, if possible,
> so that I can just pick up where I left off, and monitor it from
> here. Is this possible?

The best solution is to install the sysutils/screen port and run your
build process in a window under that.  Then you can attach to that
screen session from any number of other logins (at the same time even). 
As a side-effect, screen will protect you from accidental terminal
disconnections (if you close your xterm or ssh disconnects on you,
screen will detach the session and it will run headless until you
reattach to it).

The next-best is to use the /usr/sbin/watch command to attach to an
existing tty and see its screen output.  You'll need to rebuild your
kenel and add the "snp" device (or load it as a module).
 
> Sessions
> main desktop terminal A [ssh]--> workstation terminal A (where builds
> are currently being processed)
> 
> work desktop terminal [ssh]--> main destop terminal B [ssh]-->
> workstation terminal B
> 
> 
> I would like to have workstation terminal B intercept workstation
> terminal A, or main desktop terminal B intercept main desktop
> terminal A. Can it be done? Where do I start looking, what are the
> words and phrases of interest? I tried looking at both the bash and
> xterm commands/man page, but they are rather long, and I'd miss what
> I was looking for without having a clue in advance.
> 
> I'm guessing something like /dev/?tty?? might work, but how do I
> figure out which tty to use?

-- 
	Dan Nelson
	dnelson at allantgroup.com