setgid

   With POSIX IDs disabled, setgid is implemented for program
   portability and serves no function. It returns 0 (to indicate
   success).

   With POSIX IDs enabled, setgid sets the group IDs.

   Format

     #include  <types.h>

     #include  <unistd.h>

     int setgid  (__gid_t gid); (_DECC_V4_SOURCE)

     int setgid  (gid_t gid); (not _DECC_V4_SOURCE)
 

Additional information available:

Argument        Description     Return_Values