Introduction - If you have any usage issues, please Google them yourself
Shell program supports the development of the following commands: 1) cd <directory>- Change the current default directory <directory> . If you do not <directory> Command displays the current directory if <directory> Directory does not exist, there will be an appropriate error message. 2) clr- clear screen 3) dir <directory>- List directory <directory> Content 4) environ- lists all environment variables 5) echo <comment>- Display on the screen <comment> And line 6) help- displays the user' s manual, and use the more command filter 7) pause- stop Shell exist until you press the Enter key 8) quit- quit Shell 9) Other command-line input is interpreted as a procedure call, Shell to create and execute this program.