TPIPE
if (t->ioact != NULL || t->type == TPIPE || t->type == TCOPROC) {
case TPIPE:
while (t->type == TPIPE) {
if ((flags&XFORK) && !(flags&XEXEC) && t->type != TPIPE)
t = tl = block(TPIPE, t, p, NULL);
tl = tl->right = block(TPIPE, tl->right, p, NULL);
case TPIPE: