in reply to Grep - print matched line and next N lines

You haven't allowed for overlapping regions. If I want to print out any line matching "foo" plus the next 3 lines in the following 
qux
foo 
bar 1
bar 2
foo 
bar 1
bar 2
bar 3
qux

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Then I'd want all the lines printed from the first "foo" to the last "bar", yours only prints up to the second "foo" line.

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Re: Re: Grep - print matched line and next N lines
by runrig (Abbot) on Aug 13, 2002 at 00:08 UTC
    You haven't allowed for overlapping regions...

    I did consider it, and decided I didn't want/need that behavior, though it would make for another nifty command line option if that is the behavior you want. Feel free to patch...

    Update: Ok, its updated, though I suppose now you'll want an option to print lines from the next file if the match is at the end of the current file... :-) (though that would be easy, I think replacing the eof line with this would do it):

    last if $opt_f ? eof() : eof;

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[d/l]
      You make it sound like that behavior is non-standard in some way, but it is exactly what standard GNU grep does for the -A (--after-context) option and is typically what people would expect if you say your grep will print N lines following each matching line.
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        ..but it is exactly what standard GNU grep does ..

        Ahh, well that explains it. Although I've heard GNU grep has this option, I don't have GNU grep on my system, so I'm not familiar with exactly how it behaves (and not having GNU grep is why I wrote this in the first place). Anyway, I've reversed the meaning of the option-r to make your suggested behavior the default :-)

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