使用系统调用pipe( )建立一个管道；然后分别创建2个子进程，要求2个子进程分别向管道各写一句话：“Child 1 is sending a message!” 和 “Child 2 is sending a message!” 最后，父进程从管道中读出二个来自子进程的信息并显示。-Use the system call pipe () to create a pipeline　then create two sub-processes are required two sub-processes each write one sentence to the pipeline were: " Child 1 is sending a message!"　And " Child 2 is sending a message!"　Finally, The parent process reads the information from the two sub-processes from the pipeline and displayed.