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Linux Guide to Linux Certification, Second Edition

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Title: Linux Guide to Linux Certification, Second Edition


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

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

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

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

6
Operating Systems (continued)
Figure 1-1 The role of operating system software
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

8
Operating Systems (continued)
Figure 1-2 A Linux graphical user interface
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

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

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

12
Identifying Kernel Versions (continued)
Table 1-1 Latest revisions of common Linux
kernels
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

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

15
Licensing Linux (continued)
Table 1-2 Software types
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

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

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

19
Linux AdvantagesMeeting 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

20
Linux AdvantagesStability 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

21
Linux Advantages Flexibility for Different
Hardware Platforms
  • Partial list of hardware platforms on which Linux
    can run

22
Linux AdvantagesEase 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

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

24
Linux Advantages Cost Reduction
Table 1-3 Calculating the total cost of ownership
25
The History of Linux
Figure 1-4 Timeline of UNIX and Linux development
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

27
UNIX (continued)
  • Berkeley Software Distribution (BSD)
  • Version of the original UNIX source code
  • Common flavors of UNIX today include
  • Sun Microsystemss Solaris
  • Hewlett-Packards HP-UX
  • IBMs AIX UNIX

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

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

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

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)

32
Linux Distributions (continued)
Figure 1-5 The GNOME Desktop
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

34
Linux Distributions (continued)
Table 1-4 Common Linux distributions
35
Linux Distributions (continued)
Table 1-4 (continued) Common Linux distributions
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

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

38
Internet ServersRouting 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

39
Internet ServersFirewalls 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

40
Internet ServersWeb 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

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

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

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

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

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.

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

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

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
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