| GETGID(2) | System Calls Manual | GETGID(2) | 
getgid, getegid —
#include <unistd.h>
gid_t
  
  getgid(void);
gid_t
  
  getegid(void);
getgid() function returns the real group ID of the
  calling process, getegid() returns the effective group
  ID of the calling process.
The real group ID is specified at login time.
The real group ID is the group of the user who invoked the
    program. As the effective group ID gives the process additional permissions
    during the execution of “set-group-ID” mode
    processes, getgid() is used to determine the
    real-group-id of the calling process.
getgid() and getegid()
  functions are always successful, and no return value is reserved to indicate
  an error.
getgid() and getegid() conform
  to IEEE Std 1003.1-1990 (“POSIX.1”).
getgid() function appeared in
  Version 4 AT&T UNIX.
| April 3, 2010 | NetBSD 10.0 |