NO_PGID
retval[0] = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PGID;
pid_t pg_id = NO_PGID;
if (pg_id != NO_PGID) {
ep->e_tpgid = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PGID;
ki->p_tpgid = NO_PGID; /* may be changed if controlling tty below */
ki->p_tpgid = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PGID;
*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PGID;
if (pgid == NO_PGID)