NOS 221 Chapter 1 Powerpoint

About the Presentations• The presentations cover the objectives found in the

opening of each chapter.• All chapter objectives are listed in the beginning of

each presentation.• You may customize the presentations to fit your

class needs.• Some figures from the chapters are included. A

complete set of images from the book can be found on the Instructor Resources disc.

Linux Operations and Administration

Chapter OneIntroduction to the Linux Operating

System


Objectives

• Summarize the functions of an operating system• Identify key historical points in the development of

Linux• Explain the components of the Linux architecture

and features of the operating system

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Overview of Operating System Functions

• Linux – Practical alternative to more costly Windows and

Macintosh operating systems– Includes:

• Graphical desktop• Web browser• E-mail• Sound and video• Any other feature that Windows has to offer

4


Software Licensing Agreements

• User does not actually own the software– Only granted a license to use it

• Table 1-1 – Licensing terms

• Open source– Software distributed with its source code – Users can view or modify it

• All Linux versions are open source• Source code

– Instructions defining how a program works5


Software Licensing Agreements (cont’d.)

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Table 1-1 Licensing agreement terms


Software Licensing Agreements (cont’d.)

• Linux kernel licensed under General Public License (GPL)

• Activity 1-1: Reviewing Licensing Agreements– Examine the licensing agreement of an application of

your choice and compare it with the GPL

7


Functions of an Operating System

• Operating system– Software that’s designed to control hardware– Provides an interface between computer hardware

and software• Kernel

– Performs the most basic computing functions• Table 1-2

– Summarizes common OSs

8


Functions of an Operating System (cont’d.)

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Table 1-2 Features of common operating systems



• Most OSs include:– User interface

• Graphical user interface (GUI) – Enables users to interact with computers by using

graphical elements, such as menus and buttons• Command-line interface (CLI)

– Users communicate with the computer by typing commands

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– File systems• Find and access files

– Device drivers• Control hardware devices

– System services• Run in the background and carry out application-

related tasks

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History of Linux

• American Telephone & Telegraph (AT&T)– By 1969, 90% of American homes had AT&T phone

service– Testing and research conducted at Bell Laboratories

• UNIX operating system– Created at Bell Labs by Dennis Ritchie and Ken

Thompson– Many professors began using it for testing and

research in university labs

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History of Linux (cont’d.)

• In early 1980s, AT&T decided to license UNIX and charge institutions a hefty price to use it

• Richard Stallman – Created the GNU Project – Developed the GPL– Believes software should be free

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• GPL – You can use, view, and change the source code– You are able to redistribute the software and sell it

for a profit– If you decide to sell the software, you must make the

source code available• MINIX

– Created by Andrew Tanenbaum to teach students how to use an OS

– Source code made available to everybody

14


History of Linux (cont’d.)• Linus Torvalds

– Created his own kernel in 1991– Called the Linux kernel– Licensed through the GPL

• Many different versions (distributions)– Red Hat (www.redhat.com)– Ubuntu (www.ubuntu.com)– Debian (www.debian.org)– PCLinuxOS (http://pclinuxos.com)– FreeBSD (www.freebsd.org)– openSUSE (www.novell.com/linux)

15



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Table 1-3 Linux timeline


Overview of SUSE

• Developed in Germany in 1992 – By Hubert Mantel, Burchard Steinbild, Roland Dyroff,

and Thomas Fehr• Acronym for “Software und System Entwicklung”

– Software and System Development• Top Linux seller in Europe• Sold to Novell for $210 million

17


Overview of SUSE (cont’d.)

• OpenSUSE – Comes with the Linux kernel and the latest versions

of two desktop environments KDE and GNOME• Yet another Setup Tool (YaST)

– Configuration tool that enables administrators to install and manage software

18


Linux Architecture

• Modular system– All components are separate from one another– Makes it possible for different teams to develop

components that don’t affect one another• Linux distribution

– Consists of all the Linux components put together and released as one OS

19

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Figure 1-1 Components of the Linux architecture©Cengage Learning 2013



Linux Architecture (cont’d.)

• Kernel– Core of the OS– Manages hardware, such as disk drives and memory

• Shell– Interface that accepts and translates user input so

that the kernel can process it• Daemons

– Programs that run in the background independently of the user

– Called services in Windows

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Linux Architecture (cont’d.)

• Applications – Programs that require an OS to run – Give users a specific function, such as word-

processing programs, media players, etc.

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Kernel

• Linux kernel – Licensed under the GPL– Allows public access to the source code

• Resource manager– Manages processes and memory– Can perform multiple processes at the same time

• Process – Program the kernel launches into memory for the

purpose of performing specific tasks

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Kernel (cont’d.)

• Random access memory (RAM) – Storage space where a computer reads and writes

data– Considered “volatile” storage

• Data stored there is erased when the computer shuts down

• Demand paging– Load only needed sections of a program into RAM

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Linux Desktop Environments

• Desktop environments available in openSUSE – K Desktop Environment (KDE) – GNU Network Object Model Environment (GNOME)– Very similar– Differ mainly in the programming language used to

write them

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Figure 1-2 The KDE interface in openSUSE©Cengage Learning 2013


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Figure 1-3 The GNOME interface in openSUSE©Cengage Learning 2013



Linux File Structure

• Organized in a hierarchical, treelike structure• Top level

– Root directory– Indicated with the / symbol

• Everything in Linux is considered a file– Device files– “Regular” files– Directory files

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Linux File Structure (cont’d.)

• Device file – Special file stored in the /dev directory – Represents a hardware device on the system

• Regular files – Files containing data

• Directory file– Like a folder in Windows– Can contain files and other directories

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Features of Linux

• Multiuser– Enables multiple users to log on to a single computer

at the same time• Multitasking

– Multiple processes can run simultaneously• Preemptive multitasking

– Scheduler decides when a process stops and another process starts

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Features of Linux (cont’d.)

• Networking connectivity– Uses Transmission Control Protocol/Internet

Protocol (TCP/IP)• Internationally accepted set of rules for connecting

computers to the Internet and most other networks

• Security– Login and password authentication– File ownership and permissions – Firewall for protecting network resources from users

outside the network

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Command Shells Available in Linux

• Shell – Command-line interface between users and the

kernel• Used by administrators for more advanced

configuration tasks• Table 1-4

– Summarizes common Linux shells– Stored in the /bin directory

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Command Shells Available in Linux (cont’d.)

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Table 1-4 Common shells in Linux


Summary

• All Linux distributions – Open source and licensed under the General Public

License (GPL)• Linux distributions

– Include graphical desktop environment, a Web browser, e-mail, sound, video, and networking capability

– Comparable with rival operating systems• Kernel

– Performs the most basic computing functions

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Summary (cont’d.)

• Main user interfaces – Graphical user interface (GUI) – Command-line interface

• GNU Project– Protest against licensing UNIX as a for-profit

software product• Linux architecture

– Kernel, shell, applications, GUI, and desktop environment

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NOS 221 Chapter 1 Powerpoint

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