opendir my $dh, $dir or die "$dir: $!\n";
my @wanted = grep { m/\.(?:pd|ti)f\z/ } readdir $dh;
closedir $dh;

if ( @wanted ) {
  local $,= local $\ = $/;
  print "Folgende Dateien gefunden:",
    @wanted;
}
else {
  print "nix gefunden!\n";
}