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From: chris@pixutl.UUCP (chris)
Newsgroups: net.unix-wizards
Subject: Re: comm '! sort file1' '! sort file2'
Message-ID: <38@pixutl.UUCP>
Date: Tue, 14-Oct-86 10:43:07 EDT
Article-I.D.: pixutl.38
Posted: Tue Oct 14 10:43:07 1986
Date-Received: Fri, 17-Oct-86 08:12:36 EDT
References: <830003@hpcnoe.UUCP> <35@pixutl.UUCP> <3724@umcp-cs.UUCP> <7028@elsie.UUCP>
Organization: xePIX Inc., Nashua, N.H.
Lines: 28
Summary: fifo's

In article <7028@elsie.UUCP>, ado@elsie.UUCP (Arthur David Olson) writes:
>
> Even if a normal can create a fifo, it may not be the wisest thing to do.
> Think of the havoc that results if I put a
> 	sort "$1" > ~/fifo & sort "$2" | comm - ~/fifo
> command into a shell script (named, for example, "scomm") and then,
> six months from now when I've forgotten the implementation details,
> type in
> 	scomm firstfile secondfile > results &
> 	scomm thirdfile fourthfile > moreresults &
> 

Think of the havoc that would be created if 6 months from now you forgot
the implementation details of 'rm -r'... You can create temporary fifo's
if you want to fix that problem.
	
	[ ${#} -ne 2 ] && { echo "Usage ${0} file1 file2"; exit 1; }
	trap "rm -f /tmp/fifo$$" 0 1 2 3
	/etc/mknod /tmp/fifo$$ p || { echo "can't create fifo" ; exit 1; }
 	sort "${1}" > /tmp/fifo$$ & sort "${2}" | comm - /tmp/fifo$$

Chris
-- 

 Chris Bertin       :  (603) 881-8791 x218
 xePIX Inc.         :
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