Não dobre L em NUL :
reg query HKCU\Software\myownkey >NUL 2>&1
>null tenta redirecionar a saída do comando para um arquivo chamado null no diretório atual, que é supostamente C:\Windows ou C:\Windows\system32 .
The null device is a special file that discards all data written to it, but reports that the write operation succeeded.
It is often used to hide the output (or error output) of a command.
e.g.
SomeCommand >nul
Nulprovides no data to any process that reads from it (yieldingEOFimmediately)For more examples see the redirection page.