1. 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. 1

2. Linux+ Guide to Linux Certification, Third Edition Chapter 1 Introduction to Linux

3. Objectives Understand the purpose of an operating system Outline the key features of the Linux operating system Describe the origins of the Linux operating system Identify the characteristics of various Linux distributions and where to find them Explain the common uses of Linux in industry Linux+ Guide to Linux Certification, 3e3

4. 4 Operating Systems Computers have two fundamental components: –Hardware: physical components inside a computer –Software: set of instructions or programs that allow hardware components to manipulate data

5. Linux+ Guide to Linux Certification, 3e5 Operating Systems (continued) Hardware components include: –Processor (CPU) –Physical memory (RAM) –Hard disk drives –Sound cards –Video cards –Circuit boards

6. Operating Systems (continued) Two different types of programs are executed on a computer: –Applications: programs designed for a specific use and with which a user interacts –Operating system (OS) software: software components used to control the hardware of the computer Linux+ Guide to Linux Certification, 3e6

7. Operating Systems (continued) Device Driver: software containing instructions that the OS uses to control and interact with a specific type of computer hardware User Interface: an application program that allows the user to interact with the OS and other application programs –Can be a command line prompt or a graphical user interface (GUI) Linux+ Guide to Linux Certification, 3e7

8. 8 Operating Systems (continued) Figure 1-1: The role of operating system software

9. Linux+ Guide to Linux Certification, 3e9 Operating Systems (continued) Graphical user interface (GUI): component of an OS that the user can interact with using the keyboard or the mouse System services: applications that handle system- related tasks –Printing –Scheduling programs –Gaining network access

10. Linux+ Guide to Linux Certification, 3e10 Operating Systems (continued) Figure 1-2: A Linux graphical user interface

11. Linux+ Guide to Linux Certification, 3e11 The Linux Operating System OS used to run a variety of applications on a variety of different hardware components Multiuser and multitasking OS –Has the ability to manage thousands of tasks at the same time –Allows multiple users to access the system simultaneously

12. Linux+ Guide to Linux Certification, 3e12 Versions of the Linux Operating System Core component is called the Linux kernel –Written almost entirely in the C programming language Software can be used to modify appearance of Linux, but the kernel is common to all Linux Important to understand Linux kernel version numbers to decide which version is appropriate for user needs Good understanding of system hardware is important in deciding which kernel version to use

13. Linux+ Guide to Linux Certification, 3e13 Identifying Kernel Versions Linux kernel versions are composed of: –Major number –Minor number If odd, referred to as a developmental kernel: a kernel which is not fully tested and with implied instability If even, referred to as a production kernel: a kernel that has been thoroughly tested and is declared to be stable –Revision number

14. Linux+ Guide to Linux Certification, 3e14 Table 1-1: Latest revisions of common Linux kernels

15. Linux+ Guide to Linux Certification, 3e15 Licensing Linux Open Source Software (OSS): programs distributed and licensed so that the source code is available, free of charge, to anyone who wants to examine, utilize, or improve upon it –Format and structure of source code follows rules defined by the programming language in which it was written

16. Linux+ Guide to Linux Certification, 3e16 Licensing Linux (continued) Implications of OSS: –Developed very rapidly through widespread collaboration –Bugs (errors) are noted and promptly fixed –Features evolve quickly based on users’ needs –Perceived value of the software increases because it is based on usefulness, not on price

17. Linux+ Guide to Linux Certification, 3e17 Licensing Linux (continued) Table 1-2: Software types

18. Linux+ Guide to Linux Certification, 3e18 Types of Open Source Licenses GNU Public License (GPL): –Stipulates that the source code of any software published under its license must be freely available –Users who modify the source code must also redistribute the modified code freely Artistic license: OSS license allowing source code to be distributed freely, changed only at discretion of original author

19. Linux+ Guide to Linux Certification, 3e19 Types of Closed Source Licenses Most closed source software is sold commercially –Usually bears label of manufacturer, such as Microsoft or Electronic Arts software Freeware: distributed free of charge; source code is not available Shareware: initially free, but requires payment after a period of time or for use of certain features

20. Linux+ Guide to Linux Certification, 3e20 Linux Advantages: Risk Reduction Changes in the market or customer needs may cause companies to change software frequently –Can be costly and time-consuming Support for closed source software may end –Vendor may go out of business –Software version may be retired OSS products offer the opportunity to maintain and change the source code

21. Linux+ Guide to Linux Certification, 3e21 Linux Advantages: Meeting Business Needs Common software available for Linux includes: –Scientific and engineering software –Software emulators –Web servers, Web browsers, and e-commerce suites –Desktop productivity software –Graphics manipulation software –Database software –Security software

22. Linux+ Guide to Linux Certification, 3e22 Linux Advantages: Stability and Security Customers using a closed source OS must rely on the OS vendor to fix any bugs –Waiting for a hot fix may take weeks or months Bugs and security loopholes in OSS programs can be identified and fixed quickly –Code is freely available and scrutinized by many developers

23. Linux+ Guide to Linux Certification, 3e23 Linux Advantages: Flexibility for Different Hardware Platforms Partial list of hardware platforms on which Linux can run: Can be customized to work on mobile and embedded devices – Intel– M68K – Itanium– PA-RISC – Mainframe (S/390) – SPARC – ARM– Ultra-SPARC – Alpha– PowerPC – MIPS

24. Linux Advantages: Ease of Customization Ability to control the inner workings of the OS –To use Linux as an Internet Web server, compile the kernel to include only the support needed to be an Internet Web server Results in a much smaller and faster kernel –Can choose to install only software packages needed to perform required tasks –Can use shell and PERL scripts to customize or automate tasks Linux+ Guide to Linux Certification, 3e24

25. Linux Advantages: Ease of Obtaining Support Linux documentation can be found on the Internet –Frequently asked questions (FAQs) –HOWTO documents Linux newsgroups Linux User Group (LUG): Open forum of Linux users who discuss and assist each other in using and modifying the Linux OS Linux+ Guide to Linux Certification, 3e25

26. Linux+ Guide to Linux Certification, 3e26 Linux Advantages: Cost Reduction Table 1-3: Calculating the total cost of ownership

27. Linux+ Guide to Linux Certification, 3e27 The History of Linux Figure 1-4: Timeline of UNIX and Linux development

28. Linux+ Guide to Linux Certification, 3e28 UNIX Evolved from Multiplexed Information and Computing Service (MULTICS) The first true multitasking, multiuser OS Written in the C programming language –Portable OS OS from which Linux originated

29. Linux+ Guide to Linux Certification, 3e29 UNIX (continued) Berkeley Software Distribution (BSD) –Version of the original UNIX source code Common flavors of UNIX today include: –Sun Microsystems’s Solaris UNIX –Hewlett-Packard’s HP-UX –IBM’s AIX UNIX

30. Linux+ Guide to Linux Certification, 3e30 The Hacker Culture Hacker: someone attempting to expand their computing knowledge through experimentation –Idea of sharing knowledge is fundamental to hackers –Hacker culture set the stage for the development of Linux Cracker: someone who illegally uses computers for personal benefit or to cause damage GNU project: free OS project started by Richard Stallman –Led to publication of GNU Public License (GPL)

31. Linux First developed by Linus Torvalds in 1991 –Published under the GNU license Linux kernel developed collaboratively and centrally managed –Hackers developed Linux add-on packages and distributions –Linux is simply a by-product of OSS development Linux+ Guide to Linux Certification, 3e31

32. Linux Distributions Distribution: a collection of software containing the Linux kernel and libraries, combined with add-on software specific to a certain use. –Red Hat and SuSE Distributions may appear different on the surface, but run the same kernel Most distributions include a GUI that can be further customized to suit the needs of the user –Core component of this GUI is X Windows Linux+ Guide to Linux Certification, 3e32

33. Linux Distributions (continued) GUI environment: X Windows in combination with a window manager and desktop environment – affects the look and feel of the Linux GUI Two competing GUI environments in Linux: –GNU Object Model Environment (GNOME) –K Desktop Environment (KDE) Some Linux distributions include specific language support Linux+ Guide to Linux Certification, 3e33

34. Linux+ Guide to Linux Certification, 3e34 Linux Distributions (continued) Figure 1-5: The GNOME Desktop

35. Linux+ Guide to Linux Certification, 3e35 Linux Distributions (continued) Package manager: software system that installs and maintains software –Red Hat package manager standard on many Linux distributions Tarball: compressed archive of files containing scripts that install software to the correct location on the system –Difficult to manage, upgrade or remove from system

36. Linux+ Guide to Linux Certification, 3e36 Linux Distributions (continued) Table 1-4: Common Linux distributions

37. Linux+ Guide to Linux Certification, 3e37 Linux Distributions (continued) Table 1-4 (continued): Common Linux distributions

38. Linux+ Guide to Linux Certification, 3e38 Common Uses of Linux May be customized to provide services for a variety of companies in a variety of situations Workstation services: services used on a local computer Server services: services made available for other computers across a network

39. Linux+ Guide to Linux Certification, 3e39 Internet Servers: Mail Services Mail transfer agent (MTA): an e-mail server used to distribute email Mail delivery agent (MDA): service that downloads e-mail from an MTA Mail user agent (MUA): program that allows e-mail to be read by a user

40. Linux+ Guide to Linux Certification, 3e40 Internet Servers: Routing and FTP Services Routing: provides interconnection between separate networks –Core service necessary for Internet to function –Linux provides support for routing and is easily customizable File Transfer Protocol (FTP) Services: most common and efficient method for transferring files over the Internet

41. Linux+ Guide to Linux Certification, 3e41 Internet Servers: Firewalls and Proxy Services Firewall: Protects companies from outside intruders on the Internet –Linux has firewall support built into the kernel Proxy server: requests Internet resources such as Web sites and FTP sites on behalf of the computer inside the company –Common proxy server used on Linux is Squid

42. Linux+ Guide to Linux Certification, 3e42 Internet Servers: Web Services and News Services Web services: Web servers host information –Can process programs known as Common Gateway Interface (CGI) scripts that enable connection to a resource on the network which is not connected to the Internet –Can use Single Socket Layer (SSL) to provide secure connections News services: News servers allow users to post messages in forums called newsgroups –Most Web servers do not provide means for users to communicate

43. Linux+ Guide to Linux Certification, 3e43 Internet Servers: DNS Services Computers communicating on a network need to be uniquely identified –Each computer is assigned an Internet Protocol (IP) address Long string of numbers Allows computers to identify and reference each other Fully Qualified Domain Name (FQDN): masks IP addresses with user-friendly names DNS server: maintains a list of proper FQDN to IP mappings

44. Linux+ Guide to Linux Certification, 3e44 File and Print Servers Linux is well-suited for centrally sharing resources –More economical to share files and printers over a network –Inherently fast and light –A distribution specific to a certain task can be installed on the central server –Can share resources with a computer running another OS

45. Linux+ Guide to Linux Certification, 3e45 Application Servers Application server: intermediary between a client computer and a database Database: organized collection of data that is arranged into tables of related information Database Management Systems (DBMS): set of programs designed to allow for creation, modification, manipulation, maintenance, and access of information from databases Application servers can provide management functionality

46. Linux+ Guide to Linux Certification, 3e46 Supercomputers Clustering: combining several smaller computers to act as one large supercomputer –Beowulf clustering: most common Linux method of clustering Scalability: the ability for a computer to increase workload as the number of processors increases –Clustering computers often results in better scalability than adding processors to a single computer

47. Linux+ Guide to Linux Certification, 3e47 Scientific/Engineering Workstation Scientific and engineering community often needs customized programs OSS programs can be used or modified –OSS software available for physics, astrophysics, biophysics, biocomputation, data mining, and many other scientific and engineering fields

48. Linux+ Guide to Linux Certification, 3e48 Office/Personal Workstation Workstation software designed for end users in office and home environments OSS packages available for: –Graphics editing software –Desktop publishing software –Media software –Financial software –Office productivity suites –Bittorrent clients

49. Linux+ Guide to Linux Certification, 3e49 Summary Linux is an OS Kernel and additional software are freely developed and improved upon by a large community of software developers Published under the GPL –Called Open Source Software (OSS) Companies find Linux a stable, low-risk, and flexible alternative to other OSs

50. Linux+ Guide to Linux Certification, 3e50 Summary (continued) Comes in different distributions, all having a common kernel, but packaged with different OSS applications Wide variety of documentation and resources exist: Internet Web sites, HOWTOs, FAQs, newsgroups, and LUGs Extremely versatile OS that provides a wide range of workstation and server services