use strict;

  my $dir = "/";
  my $file;

  sub openNewDir {
      my $dir = shift;
      my $dh;
      opendir ($dh, $dir);
      while ($file = readdir ($dh)) {
          next if (($file eq '.') || ($file eq '..'));
          if (-d "$dir/$file") { openNewDir("$dir/$file"); } 
          else {
              # Do something with the file
          }
      }
      close ($dh);
  }

  openNewDir ($dir);