LINUX OPERATING SYSTEM

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CHAPTER 1

Introduction to Linux

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Overview

History of Linux GNU history Linux on the desktop Features of Linux Windows and Linux NOS comparison Operating system components

Linux Architecture

Linux Distributions

Determining Software Requirements for a Linux NOS

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History The Unix operating system was conceived and implemented in

1969 at AT&T's Bell Laboratories in the United States. It was first released in 1971 and was initially entirely written in

assembly language. Later, in 1973, Unix was re-written in the programming language C.

It was:

Simple and well-designed. Written in the C programming language . It allowed easier portability to different computer platforms.

The Bell Labs developers named their project “UNIX”

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Unix on the Desktop

UNIX was designed to support multiple users and multitasking.

It supports Internet Protocols, Internet runs powerful on UNIX systems.

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GNU History

By the 1980s, Unix was proprietary, which means that it had owners who forced users to buy it, and prevent users from edit the system code.

GNU project started by some developers, to write an Unix-like operating system.

GNU stands for “GNU's Not Unix”, which is a free operating system.

The word “free” in “free software” means freedom, not price.

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Linus and Linux

Linus Torvalds, a young man studying computer science at the university of Helsinki

Thought it would be a good idea to have some sort of freely available academic version of UNIX, and quickly started to code.

In 1991, Linux: a Unix-like kernel, was developed by Linus.

Linux + GNU software = complete operating system: the GNU/Linux system.

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Linux on the Desktop

KERNEL

Linux is a collection of software, which includes the

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Linux on the Desktop

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• The kernel is the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level.

• The communication between hardware and software components.

Features of Linux

Free Well documented Customizable Open source Multi-tasking capability Multi-users Multi-level file management

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Features of Linux

Compatibility on most hardware

TCP/IP Networking

High level of security

Virus free

Programming support for many languages

GUI support

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Linux on desktops

Disadvantages: Some users see it’s more difficult to use than Mac or

Windows. Less supported applications when compared with

Windows.

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Windows and Linux NOS Comparison

Windows has been marketed as a user-friendly, graphical interface (GUI), desktop operating system.

Linux is a very popular choice among system administrators to run their servers.

The form factors to choose the NOS are: CLI or GUI. Cost Obtaining the OS Ability to run from a CD Available application software and obtaining application software Virus resistance Security features Supporting multiple users

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operating system components

All operating system software include:

Kernel User Interface File System

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The Kernel

Kernel is the most common term for the core of the operating system.

It is a small piece of code that is loaded into memory when the computer boots.

This computer code contains instructions that allow the kernel to manage hardware devices, memory allocation, system processes, and other programs.

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The User Interface The UI is the component of the OS that the user interacts with. The UI is like an interpreter, translating user keystrokes, mouse

clicks, or other input for the appropriate programs. The UI fall into two general categories: CLI , GUI A graphic user interface (GUI) allows the user to manipulate

software using visual objects such as windows, pull-down menus, pointers, and icons.

The GUI requires more memory and storage space.

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The File System

In a hierarchical file system, files are placed in logical containers that are arranged in an upside-down tree structure.

The file system starts at the root of the tree.

UNIX and Linux call these containers “directory” and “subdirectory”.

Windows and Macintosh OSs use the term "folder" and "subfolder“.

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The File System

There are the three types of file systems: FAT (FAT16, FAT32) NTFS EX2, Ext3

Linux systems uses EX2, EX3 or JFS

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Linux Architecture

The user does not directly pass commands to the Kernel The Shell handles user interaction with the system and

Kernel

1. Controlling computer resourcesالتحكم في مصادر الحاسب

2. Allocating resources to different userالمستخدم متطلبات حسب المصادر توزيع

The Kernel is the heart of the operating system. Its main functions are:

APPLICATION

SHELL

KERNEL

HARDWARE

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Linux/UNIX CLI

UNIX and Linux support dozens of user interfaces. The most common are the text-based interfaces called shells.

Users type commands that are interpreted by the shell, which in turn relays the user instructions to the operating system and other programs.

Commonly used shells include the following: Bourne shell Korn shell Bash shell C shell TC shell

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Linux/UNIX GUI

Both UNIX and Linux are capable of running GUIs.

Because there are so many different versions of both UNIX and Linux, there are dozens of popular graphical interfaces to choose.

UNIX and Linux both rely on the X-Windows System to display the GUI.

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Linux Distributions Linux is sometimes referred to as "UNIX Lite". Linux brings the advantages of UNIX to home and

small business computers. The following are a few of the most popular types:

Red Hat Linux: the older version, the most popular Linux Mandrake: developed as a French-based version

of Red Hat Debian GNU/Linux: only built for non-profit uses. Slackware: for advanced users who prefer to use all text-

based configuration tools. Selecting a Linux distribution depends on whether the

computer will be used as a client or a server, whether or not a GUI interface is required and the experience level of the user .

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Linux Distributions23

Determining Software Requirements for a Linux NOS

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Workstation Software and Programs

The X Window System is what comprises the Linux GUI environment.

Desktop Environments help a user to customize and control their working environment.

The most popular are K Desktop Environment (KDE) and the GNU Network Object Model Environment (GNOME)

Office Tools: Corel’s WordPerfect and Sun StarOffice are the top two office suites capable of running on Linux.

Audio and visual programs available for Linux include tools for viewing and editing graphics like XV and GIMP.

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Additional Software and Programs

There are some programs and software that are essential to add to a Linux system regardless of whether it is configured as a workstation or a server.

Text editors are essential for performing any type of maintenance tasks that a user or an administrator may need to do.

Some examples of text editors available in Linux are vi or Emacs.

Programming tools are very helpful for Linux servers as well to specific users at workstations if they are programmers.

Every Linux system relies on a library called the C library (libc).

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Verifying Software Compatibility

When installing a package, always check and make sure that the operating system supports the package.

Generally, any Linux software and package can be installed on any UNIX-like operating system.

Check CPU requirements, library requirements, and development tools.

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