$(      The real gid of this  process.   If  you  are  on  a
             machine  that supports membership in multiple groups
             simultaneously, gives  a  space  separated  list  of
             groups  you  are  in.   The  first number is the one
             returned by getgid(), and  the  subsequent  ones  by
             getgroups(),  one  of  which  may be the same as the
             first number.  (Mnemonic: parentheses  are  used  to
             GROUP  things.   The real gid is the group you LEFT,
             if you're running setgid.)