利用管道技术实现父子进程间通信，具体流程：父进程以3秒为周期接收用户输入并发送到子进程，子进程接收到信息后显示并回传，父进程接收到回传信息后显示。父子进程在通信过程中采用信号中断处理方式进行处理，接收到“exit”字符串后父子进程均退出。（提示，采用SIGUSR1或SIGUSR2信号）-The use of pipeline technology communication between parent and child, the specific process: the parent process to three seconds for the cycle to receive user input sent to the child process, the child process after receiving the information display and returns the parent process receives a return message to be displayed. Parent and child processes used in the communication process interrupt signal processing methods for processing, receiving the " exit"　string both parent and child process exits. (Tip, use SIGUSR1 or SIGUSR2 signal)