The following code should do what you want. Essentially, it's a finite state machine.

Hope this helps, -gjb-

use strict;
use warnings;

my $currentPos;
my $processing = 0;
while (<DATA>) {
    chomp($_);
    if ($_ eq q(START OF RECORD)) {
        $currentPos = tell(DATA);
    } elsif (/INFORMATION I AM LOOKING FOR/ && !$processing) {
        seek(DATA, $currentPos, 0);
        $processing = 1;
    } elsif ($_ eq q(END OF RECORD)) {
        $processing = 0;
    } elsif ($processing) {
        print "$_\n";
    }
}

__DATA__

START OF RECORD
  LINE 1
  INFORMATION I AM NOT LOOKING FOR 
  LINE 3
  LINE 4
  LINE 5
  LINE 6
END OF RECORD

START OF RECORD
  LINE 1 ok
  INFORMATION I AM LOOKING FOR 
  LINE 3 ok
  LINE 4 ok
  LINE 5 ok
  LINE 6 ok
END OF RECORD

START OF RECORD
  LINE 1
  LINE 2
  LINE 3
  LINE 4
  INFORMATION I AM NOT LOOKING FOR 
  LINE 6
END OF RECORD

START OF RECORD
  LINE 1 ok
  LINE 2 ok
  LINE 3 ok
  LINE 4 ok
  INFORMATION I AM LOOKING FOR 
  LINE 6 ok
END OF RECORD
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