From mboxrd@z Thu Jan  1 00:00:00 1970
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	<56a297000909170716q6f2fe75dqf2abfbf89cb20265@mail.gmail.com>
Date: Thu, 17 Sep 2009 15:45:27 +0100
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From: roger peppe <rogpeppe@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] awk help; not plan9 matter
Topicbox-Message-UUID: 70a2ea6a-ead5-11e9-9d60-3106f5b1d025

another approach, build up a regexp and use that:

fn changefield {
	n = $1
	repl = $2
	s=')([^ 	]+)(.*)'
	for(i in `{seq 1 `{echo $n 1 -p | dc}}){
		s='[^ 	]+[ 	]+'^$s
	}
	s='('^$s
	sed 's/'^$s^'/\1'^$repl^'\3/'
}

(N.B. if the replacement string
might contain / or \, those characters would need
quoting)