SYSTEM CALLS
    setgid		- change my group id

INVOCATION
    setgid( group )
      int  group;

EXPLANATION
    The real and effective group id are set to <group>.
    Setgid(2) requires that either the caller's real group
    id is <group> or the caller is the super-user.

RESULTS
     0 : Ok.
    -1 : Error.

REFERENCES
    getgid(2)