require Algorithm::Diff;

my $file_old = "file1.log";
my $file_new = "file2.log";

open ( F1, $file_old ) or die "Can't open $file_old : $!\n";
open ( F2, $file_new ) or die "Can't open $file_new : $!\n";

my @seq1 = <F1>;
my @seq2 = <F2>;
   
close ( F1 );
close ( F2 );
 
my $diff = Algorithm::Diff->new( \@seq1, \@seq2 );

$diff->Base( 1 );   # Return line numbers, not indices