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From: stanonik@NPRDC.ARPA (Ron Stanonik)
Newsgroups: mod.computers.laser-printers
Subject: Transcript ptroff bug
Message-ID: <8609042205.AA10214@nprdc.arpa>
Date: Thu, 4-Sep-86 18:05:00 EDT
Article-I.D.: nprdc.8609042205.AA10214
Posted: Thu Sep  4 18:05:00 1986
Date-Received: Mon, 8-Sep-86 05:46:07 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 23
Approved: laser-lovers@washington.arpa

We encountered a puzzling bug in the Transcript 2.0 ptroff.
The -t option (output postscript to standout) didn't work
when piping into ptroff; eg,
	tbl file | ptroff -t
Reversing the order of the arguments to the test in the while
loop seems to cure the problem; eg,
	while test "" != "$1"
rather than
	while test "$1" != ""
Apparently
	test "$1" != ""
with $1 equal -t is interpreted as "check whether the next argument
(interpreted as a file descriptor) is a tty", rather than "check
the equality of the the strings -t and "".  As it happens, the
numerical value of != is 0; hence, the -t option worked correctly for
	ptroff -t file
but not for
	tbl file | ptroff -t
or
	ptroff -t < file

Ron Stanonik
stanonik@nprdc.arpa