dg: implement check subcommand
dg: implement check subcommand

vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam