#!perl
my $Data=<
1 is good
useless data
useless data
useless data
useless data
2 is not good
useless data
useless data
useless data
useless data
3 is good
useless data
useless data
useless data
useless data
4 is not good
useless data
useless data
useless data
useless data
HTMLend
@Results = grep {$_ =~ /is good/i} split (/
/, $Data);
$" = "\n\n";
print "@Results";