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Path: utzoo!watmath!clyde!cuae2!ihnp4!mb2c!zeta!gamma!ulysses!sfmag!sfsup!dcm
From: dcm@sfsup.UUCP
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: Lost Assignment of var in shell for loop with stdout redirection
Message-ID: <1090@sfsup.UUCP>
Date: Thu, 5-Feb-87 23:05:30 EST
Article-I.D.: sfsup.1090
Posted: Thu Feb  5 23:05:30 1987
Date-Received: Sun, 8-Feb-87 01:27:41 EST
References: <354@rlgvax.UUCP>
Reply-To: dcm@sfsup.UUCP (David C. Miller, consultant)
Organization: AT&T Information Systems, Summit, N. J.
Lines: 47
Xref: watmath comp.unix.wizards:862 comp.unix.questions:948

In article <354@rlgvax.UUCP> dennis@rlgvax.UUCP writes:
>While writing a shell script, I found an unexpected behavior
>that I thought I would share with the net.
>
>In summary, apparently
>
>for i
>do
>	var=xxx
>done >/tmp/tmpfile
>
>causes the shell interpreter to run a sub-shell, and so the value
>of $var set in the middle of a for loop is lost if $var is referenced
>after the for loop.  IS THIS CONSIDERED TO BE A sh(1) bug?
>
>-- 
>FullName:	Dennis Bednar
>UUCP:		{seismo|sundc}!rlgvax!dennis
>USMail:		CCI; 11490 Commerce Park Dr.; Reston VA 22091
>Telephone:	+1 703 648 3300

Yes, this is a know shell bug.  It also occurs with a structure like
this:

while read var
do
	# anything
done < /tmp/tmpfile

If you happen to have ksh, I'd suggest using that, since this bug has
been fixed there.  Ksh doesn't spawn a new shell to do the redirection.

Anybody have diffs to fix /bin/sh to work this way?


					Dave
--

David C. Miller, consultant
Communications Interface Addresses:
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