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From: "Rob" <listone@deathbeforedecaf.net>
To: <questions@freebsd.org>, "Brett Glass" <brett@lariat.org>
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Date: Sat, 17 Jan 2004 13:07:06 +1030
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Subject: Re: General UNIX puzzle
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Brett Glass asked on Saturday January 17, 2004:


> I was asked a good question today about how to do some simple tasks using
> standard UNIX tools, and am curious what answers people on the list might
> come up with.
>
> What are the simplest, most efficient ways to:
>
> 1) Delete the Nth line from a text file?
> 2) Insert a specified line in a file after the Nth line, leaving the rest
> of the text the same?
> 3) Delete the first line containing a particular string?
> 4) Insert a specified line after the first line containing a particular
> string, leaving the rest of the file the same?
>

Use the NR variable in nawk(1):

  nawk 'NR == 25 { next } ; { print }'

  nawk '{ print } ; NR == 25 { print "string" }'