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From: mkhaw@teknowledge-vaxc.UUCP
Newsgroups: comp.unix.questions
Subject: how to defeat pipe buffering?
Message-ID: <16207@teknowledge-vaxc.ARPA>
Date: Mon, 31-Aug-87 03:45:33 EDT
Article-I.D.: teknowle.16207
Posted: Mon Aug 31 03:45:33 1987
Date-Received: Tue, 1-Sep-87 01:15:15 EDT
Organization: Teknowledge, Inc., Palo Alto CA
Lines: 20

Ultrix comes with a modified tar program called "mdtar" that can tar to
multiple volumes of physical media.  Mdtar writes both its "v" option output
and its prompt for the next volume on stderr.  I want to "tee" the output to
a log file and just grep for the prompt to show on the controlling terminal;
e.g., (omitting details of specifying media size)

	mdtar cv . |& tee /logdir/logfile | fgrep 'Please change'

but the pipe blocks trying to read my reply to the prompt before it prints
the prompt (to put it loosely).

Is there anything I can do to get the behavior I'm aiming for? (No, I don't
have source code, and yes, I've filed an SPR with DEC.)

Thanks,
Mike Khaw
-- 
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