my $input_file = "/Users/Desktop/Pipelines/fungi.1.aa.hypothetical.faa"); my $output_file = "Users/Desktop/Pipelines/fungi.1.aa.hypothetical50.faa"); open my $in, '<', $input_file or die "could not open $input_file $!"; open my $out, '>', $output_file or die "could not open $output_file $!";