oracle linux 001

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Tuesday, June 25, 2013 Enterprise Linux By Sathish Yellanki Slide No : 1

Let Us Catch The Implementation of Oracle Enterprise Linux


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Unix Operating System Introduction


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Unix is An Operating System Which Manages The Way TheComputer Works By Driving The Processor Memory Disk Drives

Keyboards Video Monitors Web Cameras Sound Cards Printers OR Scanners

Unix Operating System Performs Useful Tasks For The EndUsers As Per The Requirement of His System Demands.

Unix Was Created in The Late 1960s As A Multiuser,Multitasking System For Use By The Computer Programmers.

The Philosophy Behind The Design of Unix Was Provide Simple, Yet Powerful Utilities Utilities Should Be Pieced Together in A Flexible Manner To Perform

A Wide Variety of Tasks.

Unix is Designed For Multiple User Management, Where MultipleUsers Can Run Multiple Tasks Simultaneously.

The Major Goal Behind The Development of Unix Was ToFacilitate Software Development With Easiness.

Unix is The Primary Operating System Used By PhysicalScientists Everywhere in The World, And All SupercomputingEstablishments in The World Are Operated on Unix.


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Linux Operating System Introduction


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In Practical Sense Linux is Basically Same As Unix. Unix Has Corporate Support And Hence it is Stable in Its

Development And Features, But Linux is Developed By UserContributions.

Most of The Features Available in Linux Are Also Applicable To

Unix And Vice Versa. Linux is A Free Open-Source Operating System Based on Unix

Features And Facilities. Linux is Free To Download, Edit And Distribute Hence Any

Hobbyist Can Participate in The Development of The Linux. We Can Consider Linux As A Full UNIX Clone, And it is Fit For

Use on Workstations As Well As on Middle-Range And High-EndServers.

Linux Includes All The Benefits Like Speed, Security AndStability As Provided By Unix And Linux Has The Ability To RunWell on More Modest Hardware.

Linux is Built From The Ground-Up With Internet-StyleNetworking And Security in Mind, Therefore Viruses, Worms,Spyware And Adware Are Basically Non-Issues on Linux.

Linux is The OS of Choice For Server Environments Due To ItsStability And Reliability As A Linux Based Server Can Run Non-Stop Without A Reboot For Years on End.

Linux is Written Totally From Scratch Without Using Any of TheOriginal AT&T UNIX Code.


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What Are Advantages of Linux Operating System?


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Low Cost The End User Need Not Spend Time And Huge Amount of Money To

Obtain Licenses As Linux And Much of it's Software Comes With TheGNU General Public License.

The End User Need Not Worry About Any Software's That He Wants To

Use in Linux.Stability Provides High Stability When Compared With Other Operating Systems. When Working With Linux We Need Not Reboot The Linux System To

Maintain Performance Levels. Linux Can Provide Continuous Up-Times of Hundreds of Days OR More.

Performance Linux Provides Guaranteed High Performance on Various Networks. Linux Has The Ability To Handle Large Number of Users Simultaneously.

Networking Linux By Default Provides A Strong Support For Network Functionality,

Hence Can Be Used To Set Up Client And Server Architecture Very Easilyon Any Computer.

Linux Can Perform Tasks Like Network Backup More Faster Than OtherOperating Systems.

Flexibility Linux is Very Flexible, Hence Can Be Used For High Performance on

Server Applications Desktop Applications Embedded Systems

We Can Install Only The Needed Components For A Particular Use AndCan Also Restrict The Use With Specific Computers.



Compatibility Linux Runs on All Common Unix Software Packages And Can Process All

Common File Formats.

Wider Choice There Are A Large Number of Linux Distributions Which Gives The End

User A Wider Choice. Being Open Source Each Organization Can Develop And Support

Different Distributions of Linux. The End User Can Pick The One That is The Best, As The Core Function's

in All The Distributions Are Same.

Fast And Easy Installation All Linux Distributions Come With User-Friendly Installation And

Configuration And Upgrade Facilities.Better Use of Hard Disk Linux Uses its Resources Well Enough Even When The Hard Disk is

Almost Full.

Multitasking Linux is A Multitasking Operating System. It Can Handle Many Things At

The Same Time.Security Linux is One of The Most Secure Operating Systems And Provides File

Ownership And Permissions Make Linux More Secure.

Open Source Linux is An Open Source Operating Systems Hence Any Body Can Easily

Get The Source Code For Linux And Edit To Develop Their Own PersonalOperating System.



What Are The Basic Entities Common in Linux And Unix



The Basic Entities Common in Unix And Linux Are Kernel

Shell

Utilities

What is Actually Meant By Kernel?

The Kernel is The Main Component of Computer OperatingSystems And it Acts Like A Bridge Between Applications AndThe Actual Data Processing Done At The Hardware Level.

The Kernel's Responsibilities Include Managing The System'sResources And The Communication Between Hardware AndSoftware Components.

The Kernel Provides Lowest-Level Abstraction For TheResources Such That Application Software Can Be Controlled ToPerform Their Functions.

Kernel Makes The Abstraction Facilities Available To TheApplication Processes Through Inter-ProcessCommunication(IPC) Mechanisms And System Calls.

The Main Tasks of The Kernel Are Process Management

Device Management

Memory Management

Interrupt Handling

I/O Communication

File System Management



Operating System Tasks Are Done Differently By DifferentKernels, Depending on Their Design And Implementation.

Basic Architecture of The Kernel

CPUCPU MemoryMemory

Applications

Kernel

MemoryCPU DevicesMemory



What Are The Types of Kernels? Broadly There Are Three Types of Kernels in Usage

Monolithic Kernels Micro Kernels Hybrid Kernels

Monolithic Kernels Monolithic Kernels Execute All The Operating System Code in

The Same Address Space To Increase The Performance. The Basic Advantages of Monolithic Kernel

In Monolithic Kernel As There is Less Software involved it is Faster. Monolithic Kernel is One Single Piece of Software Hence it is

Smaller Both in Source And Compiled Forms. Less Code in Monolithic Kernel Means That FewerBugs Hence Will

Translate To Fewer Security Problems.

KernelMode

VFS, System CallIPC, File System

Scheduler, Virtual Memory

Device Drivers, Queue, Dispatcher

Hardware

Application



Micro Kernels Micro Kernels Run Most of The Operating System Services in

User Space Called As Servers. Micro Kernels Aim At The Improvement of Maintainability And

Modularity of The Operating System. The Microkernel Approach Consists of Defining A Simple

Abstraction Over The Hardware, The Abstraction Consists of ASet of Primitives OR System Calls To Implement MinimalOperating System Services Which Include Memory Management Multitasking

Inter-Process Communication.

UserMode

ApplicationIPC

UNIXServer

DeviceDriver

FileServer

KernelMode

Basic IPC, Virtual Memory, Scheduling

Hardware

Application



Hybrid OR Modular Kernels Hybrid Kernels Are A Combination of Services of Monolithic And

Micro Kernels Together. Hybrid Kernels Are Almost Similar To Micro Kernels, Except

They Include Some Additional Code in Kernel-Space To

Increase Performance. Hybrid Kernels Are Unable To Load Modules At Runtime on

Their Own With A Compromise Between The Monolithic AndMicrokernel Designs.

UserMode

UNIXServer

FileServer

KernelMode

Application IPC Device Driver

Basic IPC, Virtual Memory, Scheduling

Hardware

Application



Kernel is The Core of The UNIX System And it is Loaded AtSystem Start Up OR The Boot Process.

Kernel Manages The Entire Hardware Resources of TheComputer System.

Functions Executed By The Kernel

Interpreting And Executing Instructions From The Shell

Managing The Machines Memory

Allocating Memory To Processes

Scheduling The Work Done By The CPUs

What is Meant By Shell?

Whenever The End User Logins To A Unix System He is Placedin A Shell Program.

The Shell is An Operating Systems Command Interpreter And itTakes Each Command And Passes it To The Operating SystemKernel To Be Acted Upon.

Shell Displays The Results of The Command Operations on ToThe End Users Screen.

Unix Systems Provide Different Types of Shells, Each With itsOwn Strengths And Weaknesses, The Different Types of Shells The Bourne Shell (SH)

C Shell (CSH And TCSH)

Bourne Again Shell (BASH)

Korn Shell (KSH)



Bourne Shell(sh) The Bourne Shell, Represented As sh is One of The Original

Shells, Developed For Unix Computers By Stephen Bourne AtAT&T's Bell Labs in 1977.

Bourne Shell is One of The Highly Tested Shell Against The Time

in The Unix World. Features Offered By Bourne Shell

Input And Output Redirection Shell Scripting With

String And Integer Variables Condition Testing Looping OR Iteration

Bourne Again Shell(bash) The Bourne Again Shell is Compatible With Bourne Shell, But

Provided With Several Enhancements. On Linux Systems bash Which is Based on sh is The Default

Standard.

bash Has The Ability To Run sh Shell Scripts Unchanged,Saving The Programmers Time. The Additional Conveniences By bash Include

Command Completion Command History

C Shell(csh And tcsh)

Using C Syntax As A Model, Bill Joy At Berkeley UniversityDeveloped The C-Shell csh, in 1978.


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Ken Greer, Working At Carnegie-Mellon University, MadeChanges on csh And Introduced A Shell Called tcsh Whichis Integrated into Linux Systems.

tcsh Fixed The Limitations in csh And Added CommandCompletion Which Makes Educated Guesses As Per The

System's Directory Structure And Files. tcsh Cannot Run bash Scripts, As The Two Have Substantial

Differences.Korn (ksh) David Korn Developed The Korn Shell ksh ksh is Compatible With sh And bash. ksh Improves on The Bourne Shell By Adding

Floating-Point Arithmetic Job Control Command Aliasing Command Completion

Utilities

Unix Provides Hundreds of Utility Programs, Often Referred ToAs Commands.

The Unix Commands Accomplish Universal Functions Such AsPrinting, Editing Files, etc.

Utilities Are The Basic OR Advanced Commands That Can BeUsed To Execute The Required Functionalities in Unix System.

The Number of Utilities Change From Version To Version AndBuild To Build

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