getgrgid
extern struct group *getgrgid(gid_t gid);
struct group* groupInfo = getgrgid(groupId);
group = getgrgid(gid);
egidName = getgrgid(eGID);
rgidName = getgrgid(rGID);
if ((groupIDName = getgrgid(groupID)) != NULL) {
while (getgrgid(gid) != NULL)