Linux+ Guide to Linux Certification by HC120808065258

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									          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
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                                                     1
 Linux+ Guide to Linux
Certification, Third 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
• 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, 3e            3
                  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




Linux+ Guide to Linux Certification, 3e                      4
        Operating Systems (continued)

• Hardware components include:
    –   Processor (CPU)
    –   Physical memory (RAM)
    –   Hard disk drives
    –   Sound cards
    –   Video cards
    –   Circuit boards




Linux+ Guide to Linux Certification, 3e   5
       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, 3e                    6
       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, 3e              7
       Operating Systems (continued)




       Figure 1-1: The role of operating system software

Linux+ Guide to Linux Certification, 3e                    8
       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



Linux+ Guide to Linux Certification, 3e           9
       Operating Systems (continued)




           Figure 1-2: A Linux graphical user interface
Linux+ Guide to Linux Certification, 3e                   10
         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




Linux+ Guide to Linux Certification, 3e                11
                 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
Linux+ Guide to Linux Certification, 3e              12
           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



Linux+ Guide to Linux Certification, 3e                       13
      Table 1-1: Latest revisions of common Linux kernels
Linux+ Guide to Linux Certification, 3e                     14
                     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




Linux+ Guide to Linux Certification, 3e                   15
          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, 3e                16
          Licensing Linux (continued)




                   Table 1-2: Software types




Linux+ Guide to Linux Certification, 3e        17
      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



Linux+ Guide to Linux Certification, 3e                 18
    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




Linux+ Guide to Linux Certification, 3e              19
                  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, 3e           20
              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, 3e           21
                 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, 3e                  22
      Linux Advantages: Flexibility for
       Different Hardware Platforms

• Partial list of hardware platforms on which Linux
  can run:
    – Intel                               – M68K
    – Itanium                             – PA-RISC
    – Mainframe (S/390)                   – SPARC
    – ARM                                 – Ultra-SPARC
    – Alpha                               – PowerPC
    – MIPS
• Can be customized to work on mobile and
  embedded devices
Linux+ Guide to Linux Certification, 3e                   23
                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, 3e                 24
              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, 3e          25
                  Linux Advantages:
                    Cost Reduction




          Table 1-3: Calculating the total cost of ownership

Linux+ Guide to Linux Certification, 3e                        26
                 The History of Linux




        Figure 1-4: Timeline of UNIX and Linux development


Linux+ Guide to Linux Certification, 3e                      27
                              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, 3e       28
                   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




Linux+ Guide to Linux Certification, 3e          29
                 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)
Linux+ Guide to Linux Certification, 3e                30
                              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, 3e                 31
                  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, 3e              32
       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, 3e           33
       Linux Distributions (continued)




                 Figure 1-5: The GNOME Desktop
Linux+ Guide to Linux Certification, 3e          34
       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



Linux+ Guide to Linux Certification, 3e               35
       Linux Distributions (continued)




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




       Table 1-4 (continued): Common Linux distributions

Linux+ Guide to Linux Certification, 3e                    37
              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, 3e           38
       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




Linux+ Guide to Linux Certification, 3e           39
               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, 3e                  40
              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




Linux+ Guide to Linux Certification, 3e                  41
           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
Linux+ Guide to Linux Certification, 3e               42
       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

Linux+ Guide to Linux Certification, 3e                     43
               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




Linux+ Guide to Linux Certification, 3e                44
                 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
Linux+ Guide to Linux Certification, 3e               45
                    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


Linux+ Guide to Linux Certification, 3e                 46
    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




Linux+ Guide to Linux Certification, 3e              47
          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

Linux+ Guide to Linux Certification, 3e            48
                          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



Linux+ Guide to Linux Certification, 3e           49
               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, 3e          50

								
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