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Linux+ Guide to Linux Certificat

VIEWS: 59 PAGES: 54

									Linux+ Guide to Linux Certification


           Chapter One

     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
  today
            Operating Systems

• Every computer has two fundamental types of
  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
        – Once a program is executed on your computer’s hardware,
          that program is referred to as a process
             Operating Systems

• Hardware components include:
  –   Processor (CPU)
  –   Physical memory (RAM)
  –   Hard disk, floppy disk, and CD-ROM drives
  –   Sound and video cards
  –   Circuit boards
               Operating Systems

• There are two
  different types or
  programs
  executed on a
  computer:
   – Applications
   – Operating
     system (OS)
     software



              Figure 1-1: The role of operating system software
                Operating System

• Device driver
   – Software containing instructions the kernel of the OS uses to
     control and interact with a specific type of computer hardware
• User interface
   – What the user sees and uses to interact with OS and application
     programs
• Graphical user interface (GUI)
   – Component of an operating system that provides a user-friendly
     interface comprising graphics or icons to represent desired
     tasks
                 Operating System
Figure 1-2: A Linux graphical user interface
                                               • System
                                                 services
                                                  – Applications
                                                    that handle
                                                    system-
                                                    related tasks
                                                    such as
                                                    printing,
                                                    scheduling
                                                    programs,
                                                    and network
                                                    access
   The Linux Operating System

• Linux
  – Operating system used today to run a variety of
    applications on a variety of different hardware
  – Has the ability to manage thousands of tasks at
    the same time, including allowing multiple users
    to access the system simultaneously
     • Hence we refer to Linux as a multiuser and
       multitasking OS
  Versions of the Linux Operating
               System
• The core component of the Linux OS is called
  the Linux kernel
• The Linux kernel and supporting function
  libraries are written almost entirely in the C
  programming language
• Though a variety of different software can be
  used to modify the appearance of Linux, the
  underlying kernel is common to all Linux
    Identifying Kernel Versions

• Linux kernel versions are comprised of:
  – Major number
  – Minor number
     • If odd, referred to as a developmental kernel
     • If even, referred to as a production kernel
  – Revision number
Identifying Kernel Versions




 Table 1-1: Latest revisions of common Linux kernels
             Licensing Linux

• Open Source Software (OSS)
  – Programs distributed and licensed so that the
    source code making up the program is freely
    available to anyone who wants to examine, utilize
    or improve upon it
  – The format and structure of source code follows
    certain rules defined by the programming
    language
             Licensing Linux

• Some implications of OSS are:
  – Software is developed very rapidly through
    widespread collaboration
  – Software bugs are promptly noted and fixed
  – Software features evolve very quickly based on
    users’ needs
  – The perceived value of the software increases, as
    it is based on usefulness and not price
              Licensing Linux




Table 1-2: Software types
  Types of Open Source Licenses

• GNU Public License (GPL)
   – Ensures that source code for any OSS will remain freely
     available to anyone
• Free Software Foundation (FSF)
   – Promotes and encourages the collaboration of software
     developers worldwide
• Artistic license
   – Open Source license that allows source code to be
     distributed freely, but changed only at discretion of
     original author
 Types of Closed Source Licenses

• Freeware
  – Distributed free of charge
  – Source code is not available
• Shareware
  – Initially free but require payment after a period of
    time or usage
Linux Advantages: Risk Reduction

• Companies invest in software to perform many
  mission-critical tasks
• Changes in the market and customer needs may
  cause companies to change software frequently
• This can be very costly and time consuming
• An OSS product offers a company the opportunity to
  maintain and change the source code
           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 Advantages:
          Stability and Security
• Customers using closed source operating systems
  must rely on the operating system vendor to fix any
  bugs
• Waiting for a hot fix may take weeks or months
• Bugs in OSS programs can be identified and fixed
  very quickly
• As Linux source code is freely available and
  scrutinized, security loopholes are also quickly
  identified and fixed
 Linux Advantages: Flexibility for
  Different Hardware Platforms
• Partial list of hardware platforms on which
  Linux can run:
  –   Intel
  –   Itanium
  –   Mainframe (S/390)
  –   Cirrus Logic ARM
  –   DEC Alpha
  –   MIPS
 Linux Advantages: Flexibility for
  Different Hardware Platforms
• Partial list of hardware platforms on which
  Linux can run (cont.):
  –   M68K
  –   PA-RISC
  –   SPARC
  –   Ultra-SPARC
  –   PowerPC (Macintosh)
         Linux Advantages:
        Ease of Customization
• The ability to control the inner workings of an
  operating system is another attractive feature
  of Linux
• For example, if you desire to use Linux as an
  Internet Web server, simply compile the
  Linux kernel to include only the support
  needed to be an Internet Web server
  – This will result in a much smaller and faster
    kernel
     Linux Advantages: Ease of
         Obtaining Support
• The Internet offers a world of Linux
  documentation
  – Frequently Asked Questions (FAQs)
  – HOWTO documents
• Linux User Group (LUG)
  – Open forum of Linux users who discuss and assist
    each other in using and modifying the Linux OS
Linux Advantages: Cost Reduction
    Table 1-3: Calculating the Total Cost of Ownership (TCO)
            The History of Linux




Figure 1-4: Timeline of UNIX and Linux development
                     UNIX

• Multiplexed Information and Computing
  Service (MULTICS)
  – Prototype time-sharing OS developed in the late
    1960s
• UNIX
  – The first true multitasking, multiuser OS
  – OS from which Linux originated
                    UNIX

• BSD (Berkeley Software Distribution)
  – Version of the original UNIX source code
• Given away free by AT&T to the University
  of California at Berkeley
• Common flavors of UNIX today include:
  – Sun Microsystems’s Solaris
  – Hewlett-Packard’s HP-UX
  – IBM’s AIX UNIX
            The Hacker Culture

• Hacker
  – Refers to someone with the intent of expanding their
    knowledge of computing through experimentation
• Cracker
  – Specifies someone who illegally uses computers for
    personal benefit or to cause damage
• GNU Project
  – Free operating system project started by Richard
    Stallman
                     Linux

• Finnish student Linus Torvalds first developed
  Linux in 1991 when he was experimenting with
  improving MINIX for the Intel x86 platform
• During the early and mid 1990s, Linux development
  was radical
• Also during this time, several distributions of
  Linux appeared, including:
  – Red Hat
  – Caldera
  – SuSE
          Linux Distributions

• Linux distribution that ship with many
  specialized tools may not contain a GUI
  – An example of this would be a Linux distribution
    that fits on a floppy and can be used as a router
• Most distribution do ship with a GUI that can
  be further customized to suit needs of the user
  – The core component of the GUI in Linux is
    referred to as X Windows
          Linux Distributions

• X Windows in combination with a window
  manager and desktop environment is referred to
  as a GUI environment
• There are two competing GUI environments in
  Linux:
  – GNU Object Model Environment (GNOME)
  – Kommon Desktop Environment (KDE)
              Linux Distributions

Figure 1-5:
The GNOME
Desktop
              Linux Distributions

Figure 1-6:
The KDE
Desktop
            Linux Distributions

• Package manager
  – Software used to install, maintain, and remove
    other software programs by storing all relevant
    information in a central software database on the
    computer
• Tarball
  – Compressed archive of files that contain scripts
    that install Linux software to the correct locations
    on the computer system
          Linux Distributions




Table 1-4: Common Linux distributions
              Linux Distributions




Table 1-4 (continued): Common Linux distributions
              Linux Distributions




Table 1-4 (continued): Common Linux distributions
        Common Uses of Linux

• Linux services may be used on the local
  computer workstation or they may be
  configured to allow other computers to connect
  to it across a network
• Services used on a local computer are referred to
  as workstation services
• Services made available for other computers
  across a network are known as server services
  Internet Servers: Mail Services

• Mail transfer agents (MTAs)
  – 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
          Internet Servers:
      Routing and FTP Services
• Routing
  – Core service that is 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
         Internet Servers:
    Firewalls and Proxy Services
• Firewalls protect companies from outside
  intruders on the Internet
• Linux has firewall support directly built into
  the kernel
• A proxy service requests Internet resources
  such as Web sites and FTP sites on behalf of
  the computer inside the company
       Internet Servers:
 Web Services and New Services
• Web services
  – Many Internet tools and services are available, the most
    popular is the Internet browser
• New services
  – Web servers host valuable information but most do not
    provide any means for users to communicate with each
    other
  – This functionality is provided by a news server, which
    allows users to post messages in forums called
    newsgroups
  Internet Servers: DNS Services

• Computers communicating on a network need
  to be uniquely identified
  – This is accomplished by assigning each computer
    a number called an Internet Protocol (IP)
    address
  – An IP addresses is a long string of numbers
  – IP addresses are masked by strings of user-
    friendly names, referred to as a Fully Qualified
    Domain Name (FQDN)
         File and Print Servers

• Networks were created to share resources,
  primarily printers and information
• Linux is well-suited to the task of centrally
  sharing resources
  – It is inherently a fast, light operating system, and
    a distribution specific to a certain task can be
    installed on the central server
          Application Servers

• Application server
  – Server running a program that acts as an
    intermediary between a client computer and
    information, normally stored in a database
• Database Management Systems (DBMS)
  – Collection of programs and tools designed to
    allow for the creation, modification,
    manipulation, maintenance, and access of
    information from databases
                Supercomputers

• Cluster
   – Several smaller computers acting as one large
     supercomputer
• Clustering
   – Act of making a cluster
   – Most common Linux method of clustering is known as
     Beowulf clustering
• Scalability
   – Ability of computers to increase workload as the number
     of processors increases
            Scientific/Engineering
                Workstations
• There are many OSS programs available in many
  different scientific and engineering fields, including:
   –   Physics, astrophysics, and biophysics
   –   Fluid dynamics and geophysics
   –   Biocomputation
   –   Materials and polymer chemistry
   –   General mathematics and optimization
   –   Data mining
   –   Number theory
          Scientific/Engineering
              Workstations
• There are many OSS programs available in many
  different scientific and engineering fields,
  including (cont.):
  –   Computer/linear/array algebra
  –   Mathematical visualization and modeling
  –   Statistics and regression analysis
  –   Data plotting and processing
  –   Computer graphics generation
  –   Computer modeling
          Scientific/Engineering
              Workstations
• There are many OSS programs available in many
  different scientific and engineering fields,
  including (cont.):
  –   Paleontology
  –   Molecular modeling
  –   Electrical engineering
  –   Artificial intelligence
  –   Geographic modeling and earth sciences
  –   Oceanography
      Office Workstations:
Text Editors and Word Processors
• Text editor
  – Program that can create and edit text files
• Word processors
  – Allow the creation and manipulation of text files
  – Typically GUI-based
Office Workstations: Graphics Editing
  and Desktop Publishing Software
• Graphics editing software
  – Includes applications designed to create and
    manipulate graphical images
• Desktop publishing software
  – Combines text and graphics editing software
    together and adds features that allow one to
    control format and layout
Office Workstations: Financial Software
     and Office Productivity Suites

• Financial software
  – Describes a family of applications designed to:
     • Track financial transactions
     • Perform bookkeeping and accounting procedures
• Office productivity suites
  – Collection of applications offered in combination
    to meet a variety of needs seen in business or the
    home
            Chapter Summary

• Linux is an operating system (OS) whose kernel
  and many additional software packages are
  freely developed and improved upon by a large
  community of software developers in
  collaboration
• Since Linux is published under GNU Public
  License, it is referred to as Open source Software
• Companies find Linux a stable, low-risk, and
  flexible alternative to other operating systems
           Chapter Summary

• Linux is available in different distributions
• There exists a wide variety of documentations
  and resources for Linux in the form of
  Internet Web sites, HOWTOs, FAQs,
  newsgroups, and LUGs
• Linux is an extremely versatile OS that can
  provide a wide range of workstations and
  server services to meet computing needs of
  companies and individuals

								
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