LINUX OPERATION

Linux is a Unix-like, open source and community developed operating system for computer, servers, mainframes, mobile, and devices and embedded devices

The Linux open source operating system, or Linux OS, is a freely distributed, cross-platforms operating system based on Unix that can be installed on PCs, laptop, networks, mobile, and tablet devices, video game console, servers, supercomputers and more. It is supported on almost every major computer platform. This operating system manages the communication between your software and your hardware. Without the operating system the software wouldn’t function.

Components of Linux system

Linux operating system has primarily three components

Kernel is the core part of Linux. It is responsible for all major activities of this operating system. The kernel “is in charge for maintaining all the vital abstractions of the operating system, together with such things as virtual memory and process. The Linux kernel forms the central parts of Linux operating system. It consists of various modules and it interacts directly with underlying hardware. The kernel implements every feature that is required to be eligible as operating system.

System library is special functions or programs which using application programs or system utilities access kernel’s features.

System libraries are [programs through which application van interrelate through the kernel. And which apply much of the operating system functionality that does not require the full rights or privileges of kernels code. Also these libraries implements most of the functionalities of the operating system and do not require kernel module’s code access right.

System utilities are the programs that execute individual, particular and specialized managing tasks. Utility programs are responsible to do specialized, individual level tasks.

Basic Features

Following are some of the important features of Linux Operating System.

Portable − Portability means software can works on different types of hardware in same way. Linux kernel and application programs support their installation on any kind of hardware platform.

Open Source − Linux source code is freely available and it is community based development project. Multiple teams work in collaborate to enhance the capability of Linux operating system and it is evolving.

Open sources follows the following key philosophies

1)      The freedom to run program, for any purpose

2)      The freedom to study how the program works, and change it to make it do what you wish

3)      The freedom to distribute copies so you can help your neighbor

4)      The freedom to distribute copies of your modified versions to others.

Multi-User: Linux is a multiuser system means multiple users can access system resource like memory / ram / application at same time.

Multitasking: Linux has the ability to handle more than one job at a time, say for example you have executed a command for sorting for a huge list and simultaneously typing in notepad. This is managed by dividing the CPU time intelligently by the implementation of scheduling policies and the concept of context switching.

Security: security is very important part of any OS, for the organization /user who is using the system for their confidential works, Linux does provide several security concepts for protecting their users from unauthorized access of their data and system.

Live CD/USB: Almost all Linux distribution have live CD/USB feature by which user can run/try the OS even without installing it on the system.

Graphical user interface (X Window System): People think that Linux is a command line OS, somewhere its true also but not necessarily, Linux have packages which can be installed to make the whole OS graphics based as Windows.

The most popular Linux distributions are:

1. Linux Mint                                                                      2. Debian

3. Ubuntu                                                                            4. openSUSE

5. Manjaro                                                                          6. Fedora

7. Zorin                                                                                 8. Elementary

9. CentOS                                                                            10. Arch Linux

VIRTUALIZATION & DOS OPERATION

OVERVIEW  OF  VIRTUALIZATION

What is virtualization?

 Virtualization: is technology of run multiple same or different operating systems which is complete isolated from each other.

Example runs both windows and Linux on the same machinelify data center management.

·         BTYPES OF VIRTUALIZATION

a.    Server virtualization

b.    Desktop virtualization

c.    Application virtualization

d.    Network virtualization

e.    Memory virtualization

f.     Data virtualization

g.    Storage virtualization

 BENEFIT OF VIRTUALIZATION

·         Reduce capital and operating costs.

·         Minimize or eliminate downtime.

·         Increase IT productivity, efficiency, agility and responsiveness.

·         Provision applications and resources faster.

·         Enable business continuity and disaster recovery.

·         Simplify data center management.

What is DOS (Disk operating system)?

DOS was the first widely installed operating system of a personal  computer

DOS control computer hardware and provide an environmental for program to run. The system program must always present when working with you computer.

DOS is a single user operating system. A single user operating system is most popular in microcomputer up mid in 1990s.

NOTE: It is also called DOS it is stored in disk of a computer.

Major Tasks of DOS is:-

      I.        To control input and output system.

   II.        To enable user to load and execute the program

 III.        To maintain orderly system of data on the disk.

DOS files

a.       BAT(batch files)

b.      COM(command files)

c.       EXE(executable files)

DOS command consist three parts: File name, parameters, switches.

Types of DOS command

A.      DOS Internal command: Are stored in the command.com file.

DOS internal command are load automatically in the memory (RAM) when you are start you system.

Some DOS Internal commands are:-

CLS – Used to clear the screen.

VER – Display the DOS version number

VOL – Display the volume label and serial.

TYPE – Display the content of a text

Exit – Exit the command processor

                (COMMAND.COM program)

B.      DOS External command: The command required less frequently. These are residing on disk.  Load automatically in the memory (RAM) only when needed.

Some of DOS External commands are:-

CHKDSK – Check the validity of the disk and report the total space, number of the file and amount of free space.

COMP – Compare the content of the two set of the files.

COMMAND – Start the command processor.

SYS – Creates a bootable drive.

COMPUTER HARDWARE

Some example  of  hardware

Computer hardware is the collection of physical components that constitute a computer system.

 Computer hardware is the physical parts or components of a computer, such as monitor, keyboard, computer data storage, hard disk drive (HDD), graphic card, sound card, memory (RAM), motherboard, and so on, all of which are tangible physical objects. By contrast, software is instructions that can be stored and run by hardware.

Hardware is directed by the software to execute any command or instruction. A combination of hardware and software forms a usable computing system.

Computer hard ware can be

1.    Input device

Input device: are any electronic device connect to the computer to produce input signal   OR

Input device: Any hardwire component that allow you to enter data and instruction into the computer example keyboard, mouse, microphone, digital camera and scanner.

2.    Output device

Output device: are hardwire that is capable delivering or showing information to one or more users. An output device display, print and represent the result of computer works. OR

Output: Monitor, printer, projector, speaker, and portable medium player.

3.       Storage devices

A storage device is any computing hardware that is used for storing, porting and extracting data files and objects. It can hold and store information both temporarily and permanently, and can be internal or external to a computer, server or any similar computing device. It refers to computer components and recording media that retain digital data. Data storage is a core function and fundamental component of computers.

Storage device: hold data instruction and information for future use                                                            

Storage's device can be divided into

        I.            Primary storage device (RAM, ROM and E PROM)

      II.            Secondary storage device (Floppy disk, hard disk, memory card, USB flash drive, DVD and CD.

COMPUTER SOFTWARE

COMPUTER SOFTWARE    

                                      COMPUTER               SOFTWARE

 Computer software / software:  Is a general term primarily used for set of instruction such as programming. OR                                                                                                     Software: “a set of a instructions given to the computer to solve a problem.”

                

 “Software is a single/ collection of programs that performs a particular task.”    Software is also called program. Different software’s are used to solve different programs.

  Software   Categories into                                                                                                                        

                          I.            System software: Is a software designed to operate the computer hardware and to provide and maintain a platform for running application software. OR

System software: Is the term referring to any computer software which manages and control the hardware so that application software can perform a task. For example operating system, compiler, loader, linker and interpreter. 

Ø       Operating system: Is software, which makes a computer to actually                             work.                                                                           It is software that enables all programs that we use.   The OS organized and control software.     OS acts as an interface between the application programs and machine hardware. Example windows, Linux, Unix and DOS

TYPES   OF   OPERATING SYSTEM

a.       GUI - Short for graphical user interface, a GUI operating system contain graphic and icons and commonly navigated by using a computer mouse.

b.      Multi-user – A multi-user operating system allows for multiples users to use the same computer at the same time and different times.

c.       Multiprocessing – An operating system capable of supporting and utilizing more than one computer processor.

d.      Multitasking – operating system that is capable of allowing multiple software processes to run at the same time.

e.      Multithreading – Operating systems that allow different parts of software program to run concurrently.

f.        Embedded system – Operating systems designed to operate on small machines like PDAs with less autonomy.  They are able to operate with limited number of resources

Ø  Compiler: Is a program that read a programs in one language – the source of language and translate into an equivalent program in another language- target language ( machine understandable language).

Ø  Interpreter: Is a computer program that translates and executing instruction written in computer programming language line –by –line, unit by unit ect.                                                                                                                                 

An interpreter needs to be able to analysis or parse, instruction written in the source language. Example lips system etc.

2.)         Application software include program that do real work for user. Example Payroll system, manage student database system, word processor etc.

UTILITY     OF     SOFTWARE

It is any system software besides the operating system that helps to maintain, manage, and protect computer system resources

IMPORTANCE

·         OS  are becoming more complex

·         Keeps computer  running smoothly

·         Helps to protect OS on the internet

EXAMPLE OF UTILITY SOFTWARE

They are much software that help to protects and keeps computer to running smoothly, such as:-

                                                        I.            Defragmentation and disks utilities

                                                      II.            Backup utilities

                                                    III.            Security software

                                                    IV.            Spam and pop-up Blockers

                                                      V.            Windows cleaners

                                                    VI.            Diagnostic software

                                                  VII.            File management utilities

                                                VIII.            CD/DVD Burners

                                                    IX.            File transfer utilities

                                                      X.            Search utilities

FUNCTION OF OPERATING SYSTEM

                                                        I.            Provide an interface to user

                                                      II.            Managing system resource

                                                    III.            Managing security and access right

                                                    IV.            Running application

                                                      V.            Process management

                                                    VI.            Memory management

                                                  VII.            Extended machine

                                                VIII.            Mastermind

                                                    IX.            Booting the computer

                                                      X.         Perform basic computer task              

INTRODUCTION OF COMPUTER

A computer is an electronic machine that performs calculations based on a set of instructions.

The first computers were huge, room-sized machines that took teams of people to build, manage, and maintain. The computer systems of today are exponentially faster and only a fraction of the size of those original computers.

                                                

TYPES OF COMPUTER                                                                                                

a.       Super computer: Is most power full available. This computer is high capacity, computer that run continuously and being use by big organization big corporation and big government institutions. User of computer include NASA and US government some big school companies. 

b.      Main frame computer: Less power full computer than super computer but capable to great processing speed, multitasking capability and high data storage. They are most used in bank to process information of depositor and millions of daily transactions.

c.       Mid- range computer / Minicomputer: Are used in medium sized of companies for specific purposes. They may be used in for certain assembly line operations or manufacturing stage in a big companies

d.      Microcomputer: Are most common and widely used computer today. There are two types which are desktop computer and notebook (laptop) computer.

e.      Tablet personal computer: Is a fancy notebook that has a swivel design and can accept handwriting using digital pen.

f.        Handheld computer: Are smallest computer that are designed to fit in one hand or palm that is why they are also called palm-top computers. This computers combine pen input personal organizer tools and command

COMPUTER NETWORK

A   DIAGRAMMATICALLY  OF  COMPUTER NETWORK

NETWORK

Networks are systems that are formed by links. 

Computer network:  Is the connection of two or more computer to the purpose of sharing resource. Resource can be hardware or software.

COMPUTER NETWORK CATEGORIES

A.      LAN’s (LOCAL ARE NETWORK)

Traditionally, a LAN is defined as a network that encompasses a small geographical area. However, the distinguishing characteristic for LAN's today is that they are typically owned by an individual, such as in a home or small business, or wholly managed by an IT department, such as in a school or corporation. This individual or group enforces the security and access control policies of the network.

A computer network is identified by the following specific characteristics:

·         Size of the area covered

·         Number of users connected

·         Number and types of services available

·         Area of responsibility

B. MAN’s (METROPOLITAN NETWORK)

A metropolitan area network (MAN) is a network that spans across a large campus or a city. The network consists of various buildings interconnected through wireless or fiber optic backbones. The communication links and equipment are typically owned by a consortium of users, or by a network service provider who sells the service to the users. A MAN can act as a high-speed network to enable sharing of regional resources.

A.   WAN's (WIDE AREA NETWORK)

A WAN connects multiple networks that are in geographically separated locations. The distinguishing characteristic of a WAN is that it is owned by a service provider. Individuals and organizations contract for WAN services. The most common example of a WAN is the Internet. The Internet is a large WAN that is composed of millions of interconnected networks. In the figure, the Tokyo and Moscow networks are connected through the Internet.

WEB SITE

WEBSITE: Is electronic representation of organization.  Or

WEBSITE: Is collection of electronic page that display organization pages

Website divided into two types

        I.            Static website: Is collection of data which do not change.

Advantages of static websites

§  Quick to develop

§  Cheap to develop

§  Cheap to host

Disadvantages of static websites

§  Requires web development expertise to update site

§  Site not as useful for the user

§  Content can get stagnant

    II.        Dynamic web site: Is collection of data which change.

Advantages of dynamic websites

§  Much more functional website

§  Much easier to update

§  New content brings people back to the site and helps in the search engines

§  Can work as a system to allow staff or users to collaborate

Disadvantages of dynamic websites

§  Slower / more expensive to develop

§  Hosting costs a little more

REQUISITE/ REQUIREMENT OF GOOD NETWORK

a.       Domain name and registration

b.      Web host

c.       Web/ blog design