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From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.shell
Subject: Re: How to pipe stderr to a command in Bourne or Korn shell
Message-ID: <7878@star.cs.vu.nl>
Date: 9 Oct 90 17:59:28 GMT
References: <1990Oct8.165133.17187@cti-software.nl> <668@atcmpe.atcmp.nl>
Sender: news@cs.vu.nl
Reply-To: maart@cs.vu.nl (Maarten Litmaath)
Organization: VU Dept. of Computer Science, Amsterdam, The Netherlands
Lines: 28

In article <668@atcmpe.atcmp.nl>,
	henk@atcmp.nl (Henk M. Keller) writes:
)In article <1990Oct8.165133.17187@cti-software.nl>,
)	pim@cti-software.nl (Pim Zandbergen) writes:
)> 
)> How can one redirect stderr to a command while leaving stdout unaffected ?
)
)The real solution in sh and ksh is to exchange stdout and stderr:
)
)	command_1 3>&1 1>&2 2>&3 3>&- | command_2

But that still does _not_ answer Pim's question!
He said: `... while leaving stdout _unaffected_' (emphasis added).
In Henk's example stdout is dup(2)ed to stderr.

So:
	exec 3>&1
	command_1 2>&1 1>&3 3>&- | command_2 3>&-
	exec 3>&-

Or:
	3>&1 (command_1 2>&1 1>&3 3>&- | command_2 3>&-)

	# yes Virginia, that's correct

Don't forget to close the extra descriptor, or you'll get screwed one day.
--
            "the C shell is flakier than a snowstorm."  (Guy Harris)