...

my $dir_txt_files = "stuff/";

tie my @array, 'Tie::File', $dir_text_files or die "Could not open file '$dir_text_files' $!";

 
 unshift @array, 'NAME, ADDRESS, ZIPCODE' unless $array[0] =~ /^[a-zA-Z]/;

 # Remove any blank lines.
 @array = grep /\S/, @array;

 untie @array;

....