Once you have logged in, the UNIX computer displays a "menu" of options that you can choose from. A sample menu might look like the one shown below:
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MAIN MENU
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1. Word Perfect
2. Lotus 123
3. Dbase IV
4. Accounting
Q. Quit (and logout)
Enter Command: _
This is the way most typical UNIX system users log in and go to work. But what really happens behind the scenes? How does this menu get shown on the screen? Where does it come from?