Introduction to computing

f software programs that run on a much deeper level than these surface uses that are essential to the usability and accessibility of any of these other programs. This type of software is called system software, without which the computer would be a nearly useless collection of plastic, metal and wires. This software governs everything from how the computer stores and interprets data to how it is analyzed and accessed and eventually displayed on the screen for user input. Additionally, how the computer responds to user signals is also managed by system software in operations that are generally never seen or even imagined by the end user. To understand how this works, it is necessary to understand the difference between the shell and the kernel embedded in the operating system as well as the main features of graphic user interfaces as opposed to command line or human/computer interfaces, ending with a look at some of the more common programs such as Unix, Linux and Windows Vista.A shell is the interface program that allows a user to communicate with the computer. Like the shell of a turtle or crustacean, the shell can be viewed as the outermost layer of the computer’s operating system. Shells incorporate a programming language to control processes and files, as well as to start and control other programs (Chapter 11, 1997). There are various ways in which a shell acts to facilitate information transfer between the user and the computer including providing the necessary prompts for user input, translating that input into language that the computer can understand and acting to turn any output from the computer into usable information back out to the user. This process can take place either through information transferred through the use of a keyboard or through the execution of a set of commands contained in a file called a shell script. When you log in to the system, the system locates the name of a shell program to execute. Once executed,