use strict; 
use warnings; 
use File::Find;

my $listings_dir = 'c:/listings'; 

find(\&callback, 'c:/tmp'); 

sub callback { 
  my $file = $_; 
 
  # Check to see if $file is a directory
  if (-d $file) {
    # Get a list of all the files in the directory (inefficient)
    # (If you only want the filenames rather than paths as well, 
    # investigate using File::Basename. If you want just the files
    # in a directory, and directories within the directory, 
    # consider putting grep { -f $_ } before the glob. 
    my (@files) = glob($File::Find::dir . "/$_/*"); 

    # Save this list to a file
    open LISTING, ">$listings_dir/list$_.txt"; 
    print LISTING join ("\n", @files); 
    close LISTING; 
  }
}