my $root_path = 'absoluter Pfad zum Startverzeichnis';
my $start_dir = 'Startverzeichnis';

opendir THEDIR, "$root_path/$start_dir" or die $!;
readdir THEDIR for 0 .. 1;
@dirs = grep -d "$root_path/$start_dir/$_", readdir THEDIR;
closedir THEDIR;

print($_, "\n") foreach @dirs;