#!/usr/bin/perl
use strict;
my ($line, @keep);
for $line ((split(/
\s+/s, join('', ())))) {
if ($line =~ m{\d+\s+is\s+good}) { push (@keep, $line); }
}
for $line (@keep) { print "$line\n"; }
__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