title: how to add user in supergroup of hdfs in linux?
body: <p>I was working on hdfs then i found something that permissions checks are not performed for the super-user.
  If my linux user is sandy and i want add sandy to group of super-user. 
  So permissions denied will not occur, is it feasible to do that in hdfs configuration.
  And if there is no problem in assigning the user to supergroup then how to do it ?</p>