ucred_getegid
set2gid = ucred_getegid(uc);
ucred_getegid(uc));
extern gid_t ucred_getegid(const ucred_t *);
state->as_egid = ucred_getegid(ucred);
dc->dc_egid = ucred_getegid(ucp);
lcred->egid = ucred_getegid(uc);