【文件格式是Linux下的gz壓縮包，在Windows下可以用WinRAR解壓】 本人原創的操作系統上機作業（源代碼），自己編寫一個簡單的Linux下的shell（a simple myshell）！原題見William Stallings寫的《Operating Systems - Internals and Design Principles》（操作系統--內核與設計原則）： The shell must support the following internal commands: cd - change the current default directory to . If the argument is not present, report the current directory. If the directory does not exist an appropriate error should be reported. This command should also change the PWD environment variable. clr - clear the screen. dir - list the contents of directory environ - list all the environment strings echo - display on the display followed by a new line (multiple spaces/tabs may be reduced to a single space) help - display the user manual using the more filter pause - pause operation of the shell until 'Enter' is pressed quit - quit the shell The shell environment should contain shell=/myshell where /myshell is the full path for the shell executable (not a hardwired path back to your directory, but the one from which it was executed)