Operating Systems and Linux

An operating system is a program that manages computer hardware and software for the user. Operating systems were originally designed to perform repetitive hardware tasks, which centered around managing files, running programs, and receiving commands from the user. You interact with an operating system through a user interface, which allows the operating system to receive and interpret instructions sent by the user. You only need to send an instruction to the operating system to perform a task, such as reading a file or printing a document. An operating system's user interface can be as simple as entering commands on a line or as complex as selecting menus and icons on a desktop.

An operating system also manages software applications. To perform different tasks, such as editing documents or performing calculations, you need specific software applications. An editor is an example of a software application that enables you to edit a document, making changes and adding new text. The editor itself is a program consisting of instructions to be executed by the computer. For the program to be used, it must first be loaded into computer memory, and then its instructions are executed. The operating system controls the loading and execution of all programs, including any software applications. When you want to use an editor, simply instruct the operating system to load the editor application and execute it.

File management, program management, and user interaction are traditional features common to all operating systems. Linux, like all versions of Unix, adds two more features. Linux is a multiuser and multitasking system. As it is a multitasking system, you can ask the system to perform several tasks at the same time. While one task is being done, you can work on another. For example, you can edit a file while another file is being printed. You do not have to wait for the other file to finish printing before you edit. As it is a multiuser system, several users can log in to the system at the same time, each interacting with the system through his or her own terminal.