Talvez meio ruim, mas coloque o comando em um arquivo de lote e redirecione a saída do arquivo de lote para o arquivo txt.
c:\echo net localgroup administrators > net_local_administrators.bat
c:\net_local_administrators.bat > %computername%-admins.txt
c:\del net_local_administrators.bat
Conteúdo de% computername% -admins.txt (nomes de membros limpos):
C:\>net localgroup administrators
Alias name administrators
Comment Administrators have complete and unrestricted access to the computer/domain
Members
-------------------------------------------------------------------------------
Administrator
MYDomain\Domain Admins
User1
User2
The command completed successfully.