If I am quoting a UNIX command or giving a Email address which
happens to end up at the end of a sentence, I put a space between the end of
the command and a period.  This isn't exactly by the rules, but it should
get the idea across.  Example follows:

        Tired of those ads on the list?  Well, telnet to cyberpromo.com .
Somehow, get the root password.  Log in as root and type  rm -r * .  This
should clear up the interference for a while.  Don't forget to go to
Washington, D.C. and collect your Metal of Honor while you pose for the
statue of you that will surely be erected in a prominent place.

Martin McCormick