#!/usr/bin/perl -w 
use strict;
my $dirname="/path/to/the/directory";
opendir(DIR,$dirname) or die "$dirname:$!";
while (my $entry=readdir(DIR)){
      next if $entry eq '.';
      next if $entry eq '..';
      next if -d $entry;  # see notes below
     | do something with this...
}
exit(0);

##</code><code>##

#!/usr/bin/perl -w 
use strict;
workTheDirectory("/path/to/the/directory");

exit(0);
#
# 
sub workTheDirectory {
     my $dirname=shift;
     opendir(DIR,$dirname) or die "$dirname:$!";
     while (my $entry=readdir(DIR)){
        next if $entry eq '.';
        next if $entry eq '..';
        if ( -d $entry ) { 
           my $newdir = $dirname . "/" . $entry; #grow the path
           workTheDirectory($newdir);
        }
     | This is a file...
     | work it.
  
     }
     return;
}