The person doing the demonstration starts an interactive shell with a command like:
csh -i |& tee /tmp/log$
csh -i 2>&1 | tee /tmp/log
Use exit to leave the shell. To start a Bourne shell, type sh instead of csh.
Everyone who wants to watch types:
and uses CTRL-c to kill tail-f when they're done.
There are a couple of gotchas:
The person who's doing the demonstration won't be able to use full-screen programs like vi that expect their outputs to go to a terminal (instead of a pipe).
Commands may echo onto the screen but not into the log file.
If that happens, type
-iv to start the demonstrator's C shell
-iv for a Bourne shell.