simdisk

代码说明：

  拟文件系统的前端操作shell 实现一个简单的shell（命令行解释器）。 将设计一的管理程序simdisk作为后台进程运行，利用本设计任务的shell操作simdisk。 本设计任务在于学会如何实现在前端的shell进程和后端的simdisk进程之间利用共享内存进行进程间通信(IPC)。 (File system front-end operations intended to implement a simple shell shell (command line interpreter). The design of a management program simdisk runs as a background process, the use of the design task shell operation simdisk. The design task is to learn how to achieve simdisk process between the front and rear shell process using shared memory for inter-process communication (IPC).)