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Linux+ Guide to Linux Certification, Second Edition

Linux+ Guide to Linux Certification, Second Edition. Chapter 1 Introduction to Linux. 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

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Linux+ Guide to Linux Certification, Second Edition

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  1. Linux+ Guide to Linux Certification, Second Edition Chapter 1 Introduction to Linux

  2. 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 today Linux+ Guide to Linux Certification, 2e

  3. Operating Systems • Computers have two fundamental components: • Hardware: Physical components inside a computer • Software: Set of instructions or programs that understand how to use the hardware of the computer in a meaningful way Linux+ Guide to Linux Certification, 2e

  4. Operating Systems (continued) • Hardware components include: • Processor (CPU) • Physical memory (RAM) • Hard disk, floppy disk, and CD-ROM drives • Sound and video cards • Circuit boards Linux+ Guide to Linux Certification, 2e

  5. Operating Systems (continued) • Two different types of programs are executed on a computer: • Applications • Operating system (OS) software • 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 Linux+ Guide to Linux Certification, 2e

  6. Operating Systems (continued) Figure 1-1: The role of operating system software Linux+ Guide to Linux Certification, 2e

  7. Operating Systems (continued) • Graphical user interface (GUI): Component of an OS that provides a user-friendly interface • System services: Applications that handle system-related tasks • Printing • Scheduling programs • Network access Linux+ Guide to Linux Certification, 2e

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

  9. The Linux Operating System • OS used to run a variety of applications on a variety of different hardware • Has the ability to manage thousands of tasks at the same time • Allows multiple users to access the system simultaneously • Multiuser and multitasking OS Linux+ Guide to Linux Certification, 2e

  10. 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 Linux+ Guide to Linux Certification, 2e

  11. Identifying Kernel Versions • Linux kernel versions are composed of: • Major number • Minor number • If odd, referred to as a developmental kernel • If even, referred to as a production kernel • Revision number Linux+ Guide to Linux Certification, 2e

  12. Identifying Kernel Versions (continued) Table 1-1: Latest revisions of common Linux kernels Linux+ Guide to Linux Certification, 2e

  13. Licensing Linux • Open Source Software (OSS): Programs distributed and licensed so that the source code is available 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 Linux+ Guide to Linux Certification, 2e

  14. 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 Linux+ Guide to Linux Certification, 2e

  15. Licensing Linux (continued) Table 1-2: Software types Linux+ Guide to Linux Certification, 2e

  16. 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 • Artistic license: OSS license allowing source code to be distributed freely, charged only at discretion of original author Linux+ Guide to Linux Certification, 2e

  17. Types of Closed Source Licenses • Most closed source software is sold commercially • e.g., 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 usage Linux+ Guide to Linux Certification, 2e

  18. 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 Linux+ Guide to Linux Certification, 2e

  19. 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 Linux+ Guide to Linux Certification, 2e

  20. 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 Linux+ Guide to Linux Certification, 2e

  21. Linux Advantages: Flexibility for Different Hardware Platforms • Partial list of hardware platforms on which Linux can run: Linux+ Guide to Linux Certification, 2e

  22. Linux Advantages:Ease of Customization • Ability to control the inner workings of an 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 Linux+ Guide to Linux Certification, 2e

  23. 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, 2e

  24. Linux Advantages: Cost Reduction Table 1-3:Calculating the total cost of ownership Linux+ Guide to Linux Certification, 2e

  25. The History of Linux Figure 1-4: Timeline of UNIX and Linux development Linux+ Guide to Linux Certification, 2e

  26. 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 Linux+ Guide to Linux Certification, 2e

  27. UNIX (continued) • Berkeley Software Distribution (BSD) • Version of the original UNIX source code • Common flavors of UNIX today include: • Sun Microsystems’s Solaris • Hewlett-Packard’s HP-UX • IBM’s AIX UNIX Linux+ Guide to Linux Certification, 2e

  28. The Hacker Culture • Hacker: Someone wanting to expand their computing knowledge through experimentation • Cracker: Someone who illegally uses computers for personal benefit or to cause damage • GNU Project: Free OS project started by Richard Stallman Linux+ Guide to Linux Certification, 2e

  29. Linux • First developed by Linus Torvalds in 1991 • Published under the GNU license • Linux kernel developed collaboratively and centrally managed • Linux is simply a by-product of OSS development Linux+ Guide to Linux Certification, 2e

  30. Linux Distributions • Red Hat and SuSE • Distributions may appear different on the surface, but run the same kernel • Most distributions ship with a GUI that can be further customized to suit needs of the user • Core component of this GUI is X Windows Linux+ Guide to Linux Certification, 2e

  31. Linux Distributions (continued) • GUI environment: X Windows in combination with a window manager and desktop environment • Two competing GUI environments in Linux: • GNU Object Model Environment (GNOME) • Kommon Desktop Environment (KDE) Linux+ Guide to Linux Certification, 2e

  32. Linux Distributions (continued) Figure 1-5: The GNOME Desktop Linux+ Guide to Linux Certification, 2e

  33. Linux Distributions (continued) • Package manager: Software system that installs and maintains software • Tarball: Compressed archive of files containing scripts that install software to the correct location on the system Linux+ Guide to Linux Certification, 2e

  34. Linux Distributions (continued) Table 1-4:Common Linux distributions Linux+ Guide to Linux Certification, 2e

  35. Linux Distributions (continued) Table 1-4 (continued): Common Linux distributions Linux+ Guide to Linux Certification, 2e

  36. 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 Linux+ Guide to Linux Certification, 2e

  37. Internet Servers: Mail Services • Mail transfer agent (MTA): An e-mail server • 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 Linux+ Guide to Linux Certification, 2e

  38. 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 Linux+ Guide to Linux Certification, 2e

  39. 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 Linux+ Guide to Linux Certification, 2e

  40. Internet Servers:Web Services and News Services • Web services: Web servers host information (text, pictures, music, binary data, and video) • Can also process programs known as Common Gateway Interface (CGI) scripts and 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 Linux+ Guide to Linux Certification, 2e

  41. 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 Linux+ Guide to Linux Certification, 2e

  42. 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 Linux+ Guide to Linux Certification, 2e

  43. 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 for creation, modification, manipulation, maintenance, and access of information from databases Linux+ Guide to Linux Certification, 2e

  44. Supercomputers • Clustering: Combining several smaller computers to act as one large supercomputer • Beowulf clustering: Most common Linux method of clustering • Scalability: Computers that can increase workload as number of processors increases Linux+ Guide to Linux Certification, 2e

  45. Scientific/Engineering Workstation • Scientific and engineering community often needs customized programs • OSS programs can be used or modified • OSS software for physics, astrophysics, biophysics, biocomputation, data mining, etc. Linux+ Guide to Linux Certification, 2e

  46. Office Workstation • Workstation software designed for end users in office and home environments • Text editors and word processors • Graphics editing software • Desktop publishing software • Financial software • Office productivity suites Linux+ Guide to Linux Certification, 2e

  47. 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; is called Open Source Software (OSS) • Companies find Linux a stable, low-risk, and flexible alternative to other OSs Linux+ Guide to Linux Certification, 2e

  48. 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 Linux+ Guide to Linux Certification, 2e

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