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From: geoff@ISM780B.UUCP
Newsgroups: net.unix-wizards
Subject: Re: Redirection quirks: 2>&1 >file  -- v
Message-ID: <28500057@ISM780B.UUCP>
Date: Mon, 6-Jan-86 09:53:00 EST
Article-I.D.: ISM780B.28500057
Posted: Mon Jan  6 09:53:00 1986
Date-Received: Wed, 8-Jan-86 20:02:41 EST
References: <649@watmath.UUCP>
Lines: 19
Nf-ID: #R:watmath:-64900:ISM780B:28500057:000:925
Nf-From: ISM780B!geoff    Jan  6 09:53:00 1986


>    $ command 2>&1 >file
>    $ command >file 2>&1
>These are not equivalent using our 4.2bsd Bourne shell.

It's a feature.  The N > &M says direct descriptor N to wherever
discriptor M is currently going. (if N is NULL, "1" is assumed.) The
command line is parsed left to right.  This feature allows you to (e.g.)
swap stdout and stderr so that stderr goes into a pipe for further
processing, (and stdout goes wherever else you want it).
Otherwise there would be no good way to get anything other than stdout
into a pipeline _by itself_.  A silly example:
$  make 2>&1 >make.out | wc -l | xargs -n1 -i echo You had {} errors.
counts only the error and warning message lines from the make output.
Not that this is the only way to do that.

	Geoffrey Kimbrough -- Director of Dangerous Activities --
	    {decvax!vortex || ihnp4!allegra!ima}!ism780!geoff
    If I can be of any help, you're in worse trouble than I thought.