COMMAND INTERPERITER:
One of the most importance system program for an operating system is the command ineterperiter which is the interface between the user and the operating system, same operating system in command interperiter in the conal.
The operating system by control statements when a new job is started in a batch system or when a user logs on to the Time share system. A program that reads and interupt control statement is executed automatically. This program is some time called control call interperiter and its aften known as the shell its function is simple to get the next command satement and execute it.
The mouse is moved to position the mouse pointer on images or icon on the screen that represents programs files and system function depending on the mouse pointer location clicking button on the mouse can invoke a program select a files and directory known as a folder or pull down a menu the contains commands.