use strict;
use warnings;
use autodie;

my $f1 = shift || "/opt/test.txt";
my $f2 = shift || "/opt/test1.txt";

my %results;
open my $file1, '<', $f1;
while (my $line = <$file1>) { $results{$line} = 1 }
open my $file2, '<', $f2;
while (my $line = <$file2>) { $results{$line}++ }
foreach my $line (sort { $results{$b} <=> $results{$a} } keys %results) { print "$results{$line}:", $line if $results{$line} >1;}