(multi-child-fd) begin
(child-close) success
child-close: exit(0)
(multi-child-fd) wait(exec()) = 0
(multi-child-fd) end
multi-child-fd: exit(0)
--OR--
(multi-child-fd) begin
child-close: exit(-1)
(multi-child-fd) wait(exec()) = -1
(multi-child-fd) end
multi-child-fd: exit(0)