管道是UNIX系统和类UNIX系统都支持的通信机制，它也是进程间通信（IPC，Inter-Process Communication）最古老的形式之一。管道是半双工的，如果要实现双向通信，需要建立两个管道。管道只能用于具有亲缘关系的进程间进行通信，如果两个完全无关的进程进行通信，则需要使用有名管道，即FIFO。

本实验父进程从控制台读数据，并向管道中写字符串。子进程将父进程经由管道传输过来的字符进行大小写互转，然后将装换后的字符送回父进程。

实验环境

Redhat9.0-Pipeline is the UNIX system and UNIX-systems support the communication mechanism, it is also inter-process communication (IPC, Inter-Process Communication) is one of the oldest forms. Pipes are half duplex, and if you want to achieve two-way communication, you need to build two pipelines. Pipeline can only be used with a genetic relationship between the process of communication, if two totally unrelated processes to communicate, you need to use named pipes, or FIFO. In this study, the parent process read data from the console, write to the pipe string. Parent process child process will be over by the tunnel system conversion case characters, and then loaded back to the parent for the character after the process. Redhat9.0 experimental environment