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From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.shell
Subject: Re: /bin/sh redirection of stdin, stderr woes
Message-ID: <8306@star.cs.vu.nl>
Date: 20 Nov 90 22:58:08 GMT
References: <28770001@hpopd.HP.COM>
Sender: news@cs.vu.nl
Reply-To: maart@cs.vu.nl (Maarten Litmaath)
Organization: VU Dept. of Computer Science, Amsterdam, The Netherlands
Lines: 37

In article <28770001@hpopd.HP.COM>,
	ian@hpopd.HP.COM (Ian Watson) writes:
)I want to have a Bourne shell script that does something like :
)
)cmd >$sout 2>$serr
)
)Under certain conditions, sout and serr may be set earlier in the script to
)given files, otherwise the stdin and stderr from the calling process are to
)be inherited.  The simple way of doing this is to have something like :
)
)if vars_were_set_in_script ; then
)	cmd >$sout 2>$serr
)else
)	cmd
)fi

Try this:

	(
		test $vars_are_set && exec > $sout 2> $serr
		cmd
	)

Alternatively:

	if some_condition
	then
		OUT="> $outputfile"
		ERR="2> $errorfile"
	fi
	...
	eval "cmd $OUT $ERR"
--
"Please DON'T BREAK THE CHAIN!  Terry Wood broke the chain and ended up
writing COBOL PROGRAMS.  Three days later, he found his Blue Star Tatoo
Letter, made 20 copies and mailed them out.  He found a good job writing
compilers."  --  tjw@unix.cis.pitt.edu (Terry J. Wood)