open (LOGFILE, "<$file") or die "Can't open $file";
my @lines = <LOGFILE>;
my $lines; my $i;
for $i(0..$#lines) {
	next unless $lines[$i] =~ /$string_to_find/i;
  	my $a = $i - 5 < 0 ? 0 : $i - 5;;
	my $b = $i + 5 > $#lines ? $#lines : $i + 5;
	for $i($a..$b) {
		print $lines[$i];
	}
}