Operating system

Operating System:

What is Operating System?

A operating system is a software that manages the computer's hardware and provides a convenient and safe environment for running programs. 

It acts as an interface between programs and the hardware resources that these programs access (like memory, hard disk and printer). It is loaded into memory when a computer is booted and remains active as long as the machine up.

Unix Operating:

Unix is a giant operating system. It has practically everything an operating system should have, and several features which other operating systems never had. Its richness and elegance go beyond the commands and tools that constitute it, while simplicity permeates the entire system. It runs on practically every hardware and provided inspiration to the open source movement.

You interact with a UNIX system through a command interpreter called shell. key in a word, and shell interprets it as a command to be executed. A command may already exist on the system as one of several hundred native tools or it could be one written by you. however power of UNIX lies in combining these commands inn the same way the English language .

Unix Architecture:

Kernel and shell

The kernel interacts with system hardware and shell interacts with user.

Kernel is the core of the operating system. A collection if routines mostly written in C. It is loaded into memory when the system is booted and communicates directly with the hardware.the programs access the kernel through a set of functions called system calls

kernel, has  great house keeping to do.

It manages the system 's memory , schedule process , decides their priorities and perform other tasks which you wouldn't like to bother about.

hardware-> kernel->shell.

Linux System Architecture is consists of following layers

Hardware layer - Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).

Kernel - Core component of Operating System, interacts directly with hardware, provides low level services to upper layer components.

Shell - An interface to kernel, hiding complexity of kernel's functions from users. Takes commands from user and executes kernel's functions.

Utilities - Utility programs giving user most of the functionalities of an operating systems.

Linux is one of popular version of UNIX operating System. It is open source as its source code is freely available. It is free to use. Linux was designed considering UNIX compatibility. It's functionality list is quite similar to that of UNIX.The defining component of a Linux-based operating system is the Linux kernel, an operating system kernel first released 5 October 1991 by Linus Torvalds. Linux kernel was originally developed as free kernel for Intel x86-based personal computers.

Basic Features

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

Portable - Portability means softwares can works on different types of hardwares in same way.Linux kernel and application programs supports 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 works in collaboration to enhance the capability of Linux operating system and it is continuously evolving.

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

Multiprogramming - Linux is a multiprogramming system means multiple applications can run at same time.

Hierarchical File System - Linux provides a standard file structure in which system files/ user files are arranged.

Shell - Linux provides a special interpreter program which can be used to execute commands of the operating system. It can be used to do various types of operations, call application programs etc.

Security - Linux provides user security using authentication features like password protection/ controlled access to specific files/ encryption of data.