Lesson 1• Unix Operating System Introduction

• Linux

• Kernel

• Directory structure

• Text editors

Unix is a layered operating system.

The innermost layer is the hardware that provides the services for the OS.

The operating system, referred to in Unix as the kernel, interacts directly with the hardware and provides the services to the user programs.

User programs interact with the kernel through a set of standard system calls.

UNIX Operating System

UNIX Features

UNIX and Linux Influencers

UNIX and Linux Influencers

Tempo1970 19901980 2000

Bell Labs (AT&T)

Ken Thompson

Dennis Ritchie (linguagem C criada para implementar um SO Minimalista

BSD (Berkeley Software Distribution)

Sun Solaris

SunOS (Stanford University Network)

NetBSD

NextStep

AIX (IBM)

HP-UX

IRIX (SGI)

SRV5

OpenBSD

FreeBSD

MacOS X

GNU / LinuxGNU

Bill Joy

Richard Stallman Linus Torvalds

Família System V

Linux is a free open-source operating system based on Unix. Linus Torvalds originally created Linux with the assistance of developers from around the world. Linux is: Free Unix Like Open Source Network operating system

Strictly speaking, Linux is a kernel.A kernel provides access to the computer hardware and control access to resources such as:Files and data; Running programs; Loading programs into memory; Networks;Security and firewall; Other resources etc.

The kernel decides who will use a resource, for how long and when.

LINUX Operating System

Kernel

• Core of the Unix system.

• Interacts directly with the OS

• Largely written in C, with some parts written in Assembly language.

• Insulates other parts of OS from hardware.

• Performs all low level functions.

• All the applications deal with Kernel.

• Handles all the devices.

Kernel Functions

• Memory management.

• Process scheduling.

• File management and security.

• Interrupt handling and error reporting.

• Input / Output services.

• System accounting

LINUX Operating System

However, the Linux kernel itself is useless unless you get all the applications such as text editors, email clients, browsers, office applications, etc.

Therefore, someone came up with idea of a Linux distribution. A typical Linux distribution includes:

Linux kernel. GNU application utilities such as text editors, browsers etc. Collection of various GUI (X windows) applications and utilities. Office application software. Software development tools and compilers. Thousands of ready to use application software packages. Linux Installation programs/scripts.

Linux post installation management tools daily work such as adding users,

installing applications, etc. And, a Shell to glue everything together.

Flavors of UNIX

Flavors of Linux/UNIXLinux is available for download over the Internet. Another way is to order the CD-ROMs.

Fedora Linux - Fedora is a distribution of Linux based on Red Hat linux, developed by the Fedora Project.

• Fedora is good for both desktop and laptop usage including sys admins.

CentOS Linux - CentOS is a community-supported, mainly free software operating system based on Red Hat Enterprise

Linux.

• CentOS is good for server usage.

Debian Linux - Debian focuses on stability and security and is used as a base for many other distributions such as Ubuntu.

• Debian stable is good for server usage.

Ubuntu Linux - Ubuntu originally based on the Debian Linux distribution.

• Ubuntu is designed primarily for desktop usage, though netbook and server editions exist as well.

OpenSuse Linux - openSUSE is a general purpose Linux distribution and sponsored by Novell.

• Popular on Laptop and desktop usage.

Slackware Linux - It was one of the earliest operating systems to built on top of Linux kernel and is the oldest currently being

maintained.

• Slackware is pretty popular among the hardcore Linux users and sys admins.

Linux Mint Linux - Linux Mint provides an up-to-date, stable operating system for the average user,

• strong focus on usability and ease of installation.

PCLinuxOS Linux - PCLinuxOS comes with KDE Plasma Desktop as its default user interface.

• a primarily free software operating system for personal computers aimed at ease of use.

Mandriva Linux - Mandriva Linux is a French Linux distribution distributed by Mandriva.

• It uses the RPM Package Manager.

Sabayon Linux - Sabayon is based upon Gentoo Linux and it follows the OOTB (Out of the Box) philosophy.

• goal to give the user a wide number of applications ready to use and a self-configured operating system.

Arch Linux - Arch Linux is a Linux distribution intended to be lightweight and simple.

• The design approach of the development team focuses on simplicity, elegance, code correctness and minimalism.

Gentoo Linux - Gentoo Linux is a computer operating system built on top of the Linux kernel and based on the Portage

package management system.

Directory structure

Text editors

vi editor