The child writes some bytes to the pointer and then exits. 子进程向指针写一些字节,然后退出。
After the fork, the parent and child have copies of all open file descriptors and data values, so the pointer works for both. 执行fork之后,父进程和子进程获得打开的所有文件描述符和数据值的拷贝,所以指针对于它们都是有效的。