Download ppt - Linux+ Guide to Linux Certification, Second Edition Chapter 1 Introduction to Linux

Linux+ Guide to Linux Certification, Second Edition

Chapter 1Introduction to Linux

Linux+ Guide to Linux Certification, 2e 2

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


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



• 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



Figure 1-1: The role of operating system software



• 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



Figure 1-2: A Linux graphical user interface


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


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


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


Identifying Kernel Versions (continued)

Table 1-1: Latest revisions of common Linux kernels


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


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


Licensing Linux (continued)

Table 1-2: Software types


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 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: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 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 Advantages: Cost Reduction

Table 1-3: Calculating the total cost of ownership


The History of Linux

Figure 1-4: Timeline of UNIX and Linux development


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


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

• 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 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 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 Distributions (continued)

Figure 1-5: The GNOME Desktop


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


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


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


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


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


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


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


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, Second Edition

Chapter 2Preparing for Linux Installation


Objectives

• Describe common types of hardware and their features

• Obtain the hardware and software information necessary to install Linux


Understanding Hardware:Central Processing Units (CPUs)

• Core component of any computer– Also known as microprocessor or processor

• Two main components:– Arithmetic logic unit (ALU): Mathematical

calculations and logic-based operations executed here

– Control unit (CU): Instruction code or commands loaded and carried out here


Understanding Hardware: CPUs (continued)

• Processor architecture: Arrangement of a processor’s integral electronics

• Two main processor architectures:– Complex Instruction Set Computer (CISC)– Reduced Instruction Set Computer (RISC)



• Clock speed: Internal time cycle of a processor – Determines speed that processor executes

commands– Measured in Megahertz (MHz)

• A processor may require one cycle to complete a command or may be superscalar

• Amount of information a processor can process at one time is a major factor in clock speed– Measured in binary digits (bits)– The more information that can be worked on at once,

the faster data can be manipulated



• Cache: Temporary store of information – Cache size and location affect a processor’s ability to

calculate larger volumes of data

• Level 1 (L1) cache: Cache stored in the processor itself

• Level 2 (L2) cache: Cache stored in a separate computer chip – Connected to processor via high speed link

• Level 3 (L3) cache: Cache stored on a separate computer chip – Connected directly to processor



• Multiple processors can work together – Perform the same tasks faster– Symmetric Multi-Processing (SMP): Allows OS and

memory to use both processors simultaneously for any task

– ASymmetric Multi-Processing (ASMP): Each processor given a set of tasks to complete independently


Understanding Hardware:Physical Memory

• Storage area for information that is directly wired through circuit boards to the processor

• Two main categories:– Random Access Memory (RAM)

• Volatile memory

– Read Only Memory (ROM)


Understanding Hardware:Physical Memory―RAM

• Requires constant supply of electricity to maintain stored information

• Directly related to computer performance

• Two major categories:– Dynamic RAM (DRAM)– Static RAM (SRAM)


Understanding Hardware:Physical Memory―RAM (continued)

• Three main types of DRAM sticks:– Single In-line Memory Modules (SIMM)

• No longer produced

– Dual In-line Memory Modules (DIMM)– Small Outline Dual In-line Memory Modules

(SODIMM)• Used in portable notebook computers and Macintosh

systems


Understanding Hardware:Physical Memory―RAM (continued)

• Three recent DIMM technologies:– Synchronous Dynamic Random Access Memory

(SDRAM)– Double Data Rate Synchronous Dynamic Random

Access Memory (DDR SDRAM)– Rambus Dynamic Random Access Memory

(RDRAM)


Understanding Hardware:Physical Memory―ROM

• Read-only Memory: Physical memory that can be read but not written to– Nonvolatile

• Basic Input/Output System (BIOS) ROM: Stores programs used to initialize hardware components when starting computer


Understanding Hardware:Physical Memory―ROM Variants

• Programmable Read Only Memory (PROM): Can only be written to once

• Erasable Programmable Read Only Memory (EPROM): Contents can be repeatedly erased and rewritten as a whole

• Electronically Erasable Programmable Read Only Memory (EEPROM): Whole or partial contents can be repeatedly erased/rewritten


Understanding Hardware:Disk Drives

• Most information in a computer maintained using nonvolatile media, not consisting of integrated circuits– Hard disk– Floppy disk– CD-ROM, DVD– CD-RW, DVD-RW disk– Zip disk– Flash Memory


Understanding Hardware:Disk Drives―Hard Disk Drives

• Not directly wired to the processor– Pass through a hard disk controller card

• Controls flow of information to and from the hard disk drive (HDD)

• Two types of controller cards:– Integrated Drive Electronics (IDE)

• Also known as Advanced Technology Attachment (ATA) controllers

– Small Computer System Interface (SCSI)


Understanding Hardware:Disk Drives―HDDs (continued)

Table 2-1: IDE HDD configurations



• Partitions: Small, manageable sections of a hard drive

• Filesystems: Specify how data should reside on the hard disk itself– A partition must be formatted with a filesystem



• Primary partitions: Major unique and separate HDD divisions

• Extended partitions: Partitions that can be further subdivided into logical drives

• Master Boot Record (MBR): Table of all partition information for a hard disk– Stored outside of all partitions



Table 2-2: Example partitioning scheme for a primary master IDE HDD


Understanding Hardware: Disk Drives―Other Information Storage

Devices• Removable media: Information storage media that

can be removed from the computer – Transferable between computers

• Floppy disks: Store information electro-magnetically – Used in floppy disk drives

• Zip disks: Similar to floppy disks– Can store much more information – Used in zip drives


Understanding Hardware: Disk Drives―Other Information Storage

Devices (continued)

• DVDs and CD-ROMs: Use lasers to read reflected light pulses– Greater data transfer speed– Larger storage capacity– More resistance to data loss than floppy disks or ZIP

disks

• Flash memory drives: Use EEPROM chips to store information


Understanding Hardware: Mainboards and Peripheral Components

• Bus: Pathway information takes from one hardware device to another via a mainboard

• Mainboard (also called a motherboard): Circuit board that connects all other hardware components together via slots or ports on the circuit board

• Peripheral components: Attach to the mainboard of a computer– e.g., video cards, sound cards, and network interface

cards (NICs)– Connected via an Input/Output bus represented by

different slots or ports on the mainboard



(continued)

• Three common slots for peripheral devices:– Industry Standard Architecture (ISA): Information

transfer at 8 MHz– Peripheral Component Interconnect (PCI):

Information transfer at 33 MHz• Can use Direct Memory Access (DMA)

– Accelerated Graphics Port (AGP): Information transfer over 66 MHz

• Designed for video card peripherals



(continued)

Figure 2-1: Mainboard components



(continued)

• Other peripherals may have external connections to mainboard– PS/2– COM (Serial)– LPT– USB– IEEE1394 (Firewire)– PCMCIA



(continued)

• Personal Computer Memory Card International Association (PCMCIA) ports: Allow a small card to be inserted into the computer with electronics necessary to provide certain functionality

• Advanced Power Management (APM): BIOS feature that shuts off power to unused peripheral devices



(continued)• Interrupt Request Line (IRQ): Specifies a unique

channel from a device to the CPU• Input/Output (IO) address: Small working area of

RAM where CPU can pass information to and receive information from a device

• Plug-and-Play (PnP): OS and peripheral devices that automatically assign the correct IRQ, I/O address, and DMA settings


Understanding Hardware: Video Adapter Cards and Monitors

• Video adapter cards: Provide graphical display when connected to a monitor– Commonly referred to as video cards

• Resolution: Total number of pixels that can be displayed on a computer video screen

• Color depth: Total set of colors that can be displayed on a computer video screen



(continued)

Table 2-3: Memory requirements for screen resolution and color depths



(continued)

• Refresh rate: Rate at which information displayed on a video screen is refreshed– Measured in Hertz (Hz)– Two types of refresh rates:

• HSync (horizontal refresh)

• VSync (vertical refresh)


Understanding Hardware:Keyboards and Mice

• Facilitates user input and direction

• Variety of ways to connect to motherboard– Serial port– Large circular AT 5-pin connector– Small circular PS/2 6-pin connector– USB connection– Wireless or radio connection

• Check hardware components against a Hardware Compatibility List (HCL)


Gathering Preinstallation Information

Table 2-4: Red Hat 7.2 hardware requirements


Gathering Preinstallation Information (continued)

Table 2-5: Sample pre-installation checklist


Gathering Preinstallation Information (continued)

Table 2-5 (continued): Sample pre-installation checklist


Gathering Hardware Information

• Tools and resources to check hardware against a preinstallation checklist:– Computer manuals– Windows System Information tool (if Windows

already installed)– Windows Device Manager (if Windows already

installed)


Gathering Hardware Information (continued)

Figure 2-2: The Windows System Information tool



Figure 2-3: The Windows Device Manager



Figure 2-4: The Windows Display applet



Figure 2-5: System Power-On Self Test (POST)



Figure 2-6: BIOS Setup Utility


Gathering Software Information

• Identifying system network configuration:– Hostname– IP address– Netmask– Gateway– DNS servers

• Resolve FQDNs


Gathering Software Information (continued)

• Dynamic Host Configuration Protocol (DHCP) server: Server on network providing IP configuration to requesting computers– If selected during installation, Linux will attempt to

get IP settings from a DHCP server on the network



Table 2-6: Common Linux packages



Table 2-6 (continued): Common Linux packages