If I understand you right, for each directory that you go into, you want to create modified versions of all the files inside that directory, and you also want to create a single file, next to that same directory (not inside it), that contains the concatenation of all the modified file contents.

There are many ways to go about this, but the method that would probably involve the least amount of code revision would be for the "dir_explorer" function to go something like this:

sub dir_explorer
{
  my $entry = $_ ;
  if (-d $entry) { 
     ...  # ignore . and .. 
     opendir(DIR, $entry) or die "Can not open $entry: $!";
     # don't bother with "open(FILE, ">>$entry.tab")
     while ( defined( my $file = readdir DIR ) {
        if ( -f "$entry/$file" ) {
           textsformat( "$entry/$file" );
        }
        # now "$entry/$file.txt" should exist, so:
        system "cat $entry/$file.txt >> $entry.tab";
     }
     closedir DIR:
  }
}
[download]