Operating system command-line interfaces
Operating system (OS) command line interfaces are usually distinct programs supplied with the operating system.
A program that implements such a text interface is often called a command-line interpreter, command processor or shell.
Application command-line interfaces
Application programs (as opposed to operating systems) may also have command line interfaces.
An application program may support none, any, or all of these three major types of command line interface mechanisms:
1. Parameters: Most operating systems support a means to pass additional information to a program when it is launched. When a program is launched from an OS command line shell, additional text provided along with the program name is passed to the launched program.
2. Interactive command line sessions: After launch, a program may provide an operator with an independent means to enter commands in the form of text.
3. OS inter-process communication: Most operating systems support means of inter-process communication (for example; standard streams or named pipes). Command lines from client processes may be redirected to a CLI program by one of these methods.
Menu Interface
This type of interface lets you interact with a computer or device by working your way through a series of screens or menus.
Think about your iPod or mobile phone, they both use a menu driven interface. You are presented with a menu, you make a choice and then the next menu appears on the screen. You make another choice and so on.
Cashpoint machines (ATMs) are another good example of a menu driven interface.
Menu driven interfaces can also be verbal rather than visual. Have you ever made a telephone call and been asked to 'press 1 for abc, press 2 for def, press 3 for ghi'?
Most of the software that you use have menu interfaces. You can use many features of the software by working your way through the menu options. Have a look at the menus in your word processor or spreadsheet package and see how many different choices you are given.
A well designed menu interface is simple to use, you just follow the instructions and make your choices.
| Advantages and Disadvantages | |
| Advantages | Disadvantages |
| Extremely easy to use. Someone who has never seen the interface before can work out what to do | A poorly designed menu interface may be slow to use |
| There are no commands to learn or remember | It can be irritating if there are too many menu screens to work through - users get annoyed or bored if it takes too long |
| Step-by-step options are given so that the user doesn't have to remember anything | You often can't go to the exact place you want right at the start. You have to work your way through the menu screens even if you know where you want to get to. |
| Even if you don't know what to do, you can usually guess your way around the options | The menu can take up a large part of the screen so you have to keep flicking back and forwards between applications |
| Menu interfaces don't have to be visual, they can be spoken - good for telephones or for visually impaired people | If the menu is poorly designed it might be hard to read e.g. writing is too small for people with poor sight, colours might clash and be difficult to read, font style might be hard to read. |
Table 6- Advantages and Disadvantages
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