INTRODUCTION TO LINUX SYSTEMS

WHAT IS AN OPERATING SYSTEM?

The operating system is a master control program that runs on the computer when the system gets started, where it runs all other computer programs. The other computer program includes applications and application programs. The application program requests or communicates with the operating system through a special interface called Application Program Interface (API). Users can interact directly with an operating system through a special interface through the command line or Graphical User Interface. OS carry out the Services like Multitasking, Memory management, handling input and output hardware devices and many. There are different types of Operating system are used, here tutorial will be covered on OS which is open source causing a revolution in the computer world.

WHAT IS LINUX?

Linux is a free and open source operating system created by Linus Torvalds in Nineties with the assistance of a group of developer’s community. This is only the operating system which dominates the world market in short span of years. Today more 97 percent of world supercomputers and more than 80 percent of smartphones, around 70 percent of all web servers and a large chunk of tablet computers and many more embedded devices run on Linux operating system. Latest Linux version 4.11 was released in April 2017.


LINUX VS WINDOWS:

Having access to the source code is probably the single most significant difference between Linux and windows. The fact that Linux belongs to GNU Public License which ensures that users can access the code to the kernel, which serves as the foundation of Linux operating system. But in windows unless if you are an elite member of a group, you cannot have an eye on windows operating system code. Still, there is much difference between Linux and windows lies, this one is major difference among them.


WHAT IS OPEN SOURCE?

The major five points can be listed under the open source:

  • Freedom of software

  • Freedom of use

  • Freedom of modifying

  • Freedom of copy

  • Freedom of redistributing

OPEN SOURCE ORIGIN – HOW IT’S ALL STARTED:

In 1983 Richard Stallman launched a GNU project to write a complete operating system free from constraints on the use of its source code. Stallman also launched a GNU manifesto in 1985 to outline the GNU project purpose and explain the importance of the free software. In 1986 Free software Foundation was started to promote the free software concept and free software definition. In 1989 the first version of GNU General Public License (GPL) was published.

During 1991 Finnish Engineer Linus Torvalds developed a core OS functionality called it's as “Linux Kernel”. Linux Kernel has got under the GPL License which laid the strong platform for the success of the Open source.


HOW IT’S EVOLVED:

Multiple Linux distribution has been started emerging around the Linux Kernel. There are also some applications became platform independent. The software model began to widespread adoption with Linux kernel in 1991 and to be used primarily for freeware and open source software. Building a business around the open source has become viable. Red hat set the initial trend in the OS business and canonical started sending out the compact disks with Ubuntu Linux and quickly become popular for home users. As like Debian, Centos now there are hundreds of Linux distributions is available.

APPLICATIONS UNDER OPEN SOURCE:

Nowadays the open sources started to have a large impact in many fields, below are some applications:

OS

  • Red Hat

  • Android

  • Canonical

Databases

  • Enterprise DB

  • My SQL

  • VoltDB

Consumer

  • Mozilla

  • Open Office

  • Libre Office

Server/Cloud

  • Open NMS

  • Open Stack

  • Cloud Stack

Education

  • Canvas

  • Docebo

  • Moodle

ecommerce

  • Magento

  • Spree

  • open cart

OPEN SOURCE VS FREEWARE:

OPENSOURCE

  • The user has right to access and modify the code.

  • In case original programmer disappeared, users & developer group of software usually keep support to software.

  • Open source usually has strong users and developers group that manage and maintain the project.

FREEWARE

  • Free wares are usually distributed in the form of binary at ‘Free of Charge’ but not source code itself.

  • The developer of freeware could abandon development at any time and then final version will be the last version of the freeware. No enhancements will be made by others.

  • The possibility of Changing its Licence Policy.

GENERAL PUBLIC LICENSE (GPL):

General Public License is widely used free software license which guarantees end user the freedom to run, share, study and modify the software. The purpose of the GPL license is to increase the amount of publically available software and ensure compatibility. GPL is the copy left license, which means derivative work can be distributed under the same license terms.


PROPERTIES OF LINUX:

Here are some properties which made the Linux scale from mobile devices to powering 90% of the world supercomputers.


MULTI - TASKING:

Multitasking is the ability to handle multiple tasks across single or multiple processors.


MULTI - USERS:

It has users with different level of privileges for secure access.


PROTECTED MEMORY:

Clear distinction called ‘user-space’ and ‘kernel space’ thereby having protected memory access. This makes Linux super secure comparing with the other operating system.


HIERARCHIAL FILE SYSTEM:

It has the well organized file system that handles various types of file. This also makes handling various inputs very simple.

LINUX COMPONENTS:

HARDWARE CONTROLLERS:

This subsystem is comprised of all the possible physical devices in a Linux installation - CPU, memory hardware, hard disks.


LINUX KERNEL:

The kernel abstracts and mediates access to the hardware resources, including the CPU. A kernel is the core of the operating system.


O/S SERVICES:

These are services that are typically considered part of the operating system (e.g. windowing system, command shell).


USER APPLICATION:

The set of applications in use on a particular Linux system (e.g. Web browser).


LINUX DIRECTORY STRUCTURE:

The File system Hierarchy Standard (FHS) defines the directory structure and directory contents in UNIX like operating system. It is maintained by Linux Foundation. In FHS all files and directories appear under the root directory /, even if they are stored on different physical and virtual devices.

/ - Root directory

/home - User home directories

/root - Root user’s home directory

/bin - Essential user command binaries

/sbin - Essential super user command binaries

/lib - Essential shared libraries and kernel modules

/usr - Multi user utilities and application

/opt - Add on application software packages

/etc - Host Specific configuration

/dev - Device files

/media - Mount point for removable media

/mnt - Mount point for temporarily mounted file systems

/boot - Static bootable images

/tmp - Temporary files

/var - Variable files

/proc - Virtual File system documenting kernel and process status.

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