学习如何编写一个UNIX的外壳——Shell，即命令解释程序。学习怎样接受命令，解释命令、执行命令，特别是创建子进程的方式来执行一个程序，以及父进程如何继续子进程的工作。-Learn how to write a UNIX shell- Shell, the command interpreter. Learning how to receive an order to explain the command, the command, in particular, the way is to

实现一个简单的shell（命令行解释器），类似于bash, csh等。本设计的主要目的在于学会如何在Unix系统下创建进程和管理进程。-A simple shell (command line interpreter) and, similar to bash, csh. The main purpose of this design is to learn how to create a process and management process on Unix systems