一个FORK（）调用的实验。通过建立共享内存区来实现进程之间的通信。父进程获取Fibonacci数列长度后，创建子进程来计算，待子进程完成后，父进程输出结果-A FORK () call experiment. Through the establishment of shared memory areas to achieve communication between the process. Parent process for the length of Fibonacci sequence, create the child process to calculate, when the child process is completed, the output of the parent process