kri54sub has asked for the wisdom of the Perl Monks concerning the following question:

I need to print out lines (from multiple files) starting from a string "Server error:" to a line above the string "server info", only if I see a pattern /Btree/ within this text block. I tried using the flip-flop operator but it did not give me the desired result. The grep -B# -A# works but the number of lines within the text block may vary. Hence the grep approach does not suit me. Can you send me your thoughts?

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Re: Newbie : Data mining question
by jasonk (Parson) on Oct 29, 2007 at 20:21 UTC 
    for ( $content =~ /^(Server error:\n.*?)^server info/gsm ) {
    print if /Btree/;
}

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      Replacing for with while would save memory at no cost.

      Update: Oops, not quite true. It would involve copying $1 into some other variable, so it might lose speed. 

      while ( $content =~ /^(Server error:\n.*?)^server info/gsm ) {
    my $record = $1;
    print $record if $record =~ /Btree/;
}

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