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From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.sources.wanted,alt.sources,misc.wanted
Subject: Re: duplicate output to multiple terminals
Message-ID: <1989Nov10.141433.3197@virtech.uucp>
Date: 10 Nov 89 14:14:33 GMT
References: <256@telxon.UUCP> <4647@cbnewsc.ATT.COM>
Organization: Virtual Technologies Inc.
Lines: 27

In article <4647@cbnewsc.ATT.COM>, psfales@cbnewsc.ATT.COM (Peter Fales) writes:
> 	cu XXXX	| tee /tmp/tmpfile
> 
> [text deleted...] 
> 
> 	tail -f /tmp/tmpfile
> 
> I don't totally understand why this works, but it does.  You can even
> see all the "teacher's" key strokes in real time.

The reason that this works is that cu starts up two programs, one that 
takes all of you're keyboard input and writes it out the communications port and
one that reads all of the data comming in the comm port and writes it to stdout.

In your example stdout is the tee, which copies the data to the logfile and
writes it to the terminal.  Since the data is being written to the log file,
the students that read the log file will see all data comming from the comm
port.

You don't see all of the teacher's keystrokes, you see all of the data ouput
from the system to the terminal.  Many of the teacher's keystrokes are echoed
back by the system so that is why you see most of them.
-- 
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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
| Virtual Technologies Inc.,    P. O. Box 876,   Sterling, VA 22170     |
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