1. see File::Compare - Compare files or filehandles

2. Or you can try something like,

my %data_hash;
   open(my $fh, '<', "datafile.txt") or die $!;
   while(<$fh>){
    $data_hash{$_} = 1;
   }
   close($fh);
   open(my $fh1, '<', "tmpfile.txt") or die $!;
   while(<fh1>){
    if(defined($data_hash{$_})){
     print"Line match";
    }else{
    print"Line not match";
    }
   }
   close($fh2);
   close($fh1);
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