1. Chapter One
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
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

4. Operating Systems 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
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

6. Operating System Device driver User interface
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

7. Operating System System services
Figure 1-2: A Linux graphical user interface
System services
Applications that handle system-related tasks such as printing, scheduling programs, and network access

8. The Linux Operating System
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

9. 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

10. 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

11. Identifying Kernel Versions
Table 1-1: Latest revisions of common Linux kernels

12. 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

13. 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

14. Licensing Linux
Table 1-2: Software types

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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)

22. 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

23. 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

24. Linux Advantages: Cost Reduction
Table 1-3: Calculating the Total Cost of Ownership (TCO)

25. The History of Linux
Figure 1-4: Timeline of UNIX and Linux development

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

27. 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

28. The Hacker Culture Hacker Cracker GNU Project
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

29. 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

30. 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

31. 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)

32. Linux Distributions
Figure 1-5: The GNOME Desktop

33. Linux Distributions
Figure 1-6: The KDE Desktop

34. Linux Distributions Package manager Tarball
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

35. Linux Distributions
Table 1-4: Common Linux distributions

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

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

38. 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

39. Internet Servers: Mail Services
Mail transfer agents (MTAs)
An server
Mail delivery agent (MDA)
Service that downloads from an MTA
Mail user agent (MUA)
Program that allows to be read by a user

40. Internet Servers: Routing and FTP Services
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

41. 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

42. Internet Servers: Web Services and New 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

43. 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)

44. 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

45. 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

46. Supercomputers Clustering Cluster Scalability
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

47. 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

48. 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

49. 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

50. Office Workstations: Text Editors and Word Processors
Program that can create and edit text files
Word processors
Allow the creation and manipulation of text files
Typically GUI-based

51. 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

52. Office Workstations: Financial Software and Office Productivity Suites
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

53. 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

54. 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