Linux Operaring System chapter one Introduction.pptx

Red Sea University
Computer Science & IT

http://www.mahergelle.com
By Eng.Adulahi M. Adan
Operating System 2: LINUX

Chapter One: -
Introduction to
Linux

Chapter Outline
Operating Systems
01
Unix/Linux OS
02
Linux vs Windows
03
Why Linux
Which Linux
How Linux
04

OPERATING SYSTEMS
What is an OS?
Why have one?
What is a Kernel?
Linux Operating System

OPERATING SYSTEMS
 Operating system: manages activities and resources of a computer.
• Software that acts as an interface between hardware and user
• Provides a layer of abstraction for application developers
 Features provided by an operating system:
• Ability to execute programs (and multi-tasking)
• Memory management (and virtual memory)
• File systems, disk and network access
• An interface to communicate with hardware
• A user interface (often graphical)

OPERATING SYSTEMS
• Computer System Structure
Computer system can be divided into four components:
1. Hardware – provides basic computing resources CPU, memory, I/O devices
2. Operating system:- Controls and coordinates use of hardware among
various applications and users
3. Application programs – define the ways in which the system resources are
used to solve the computing problems of the users Word processors, web
browsers, database systems, video games
4. Users: - People, machines, other computers

OPERATING SYSTEMS

OPERATING SYSTEMS Evolution
• The history of the operating system has four generations now. The evolution
of the Operating system can be understood from the following image.

OPERATING SYSTEMS
• The software that contains the core components of the operating system is
called the kernel.
• kernel: The lowest-level core of an operating system.
Date Event History of Operating System - Description
0s-1940s No OS Manual machine language input; limited accessibility due
to expertise.
1940s-50s Batch Processing Introduction of punch card-based programming;
sequential job processing.
1960s-70s Time-Sharing CPU time shared among programs at intervals; interactive
computers.

OPERATING SYSTEMS
1970s-80s Introduction of GUI Adoption of GUIs with icons, menus, and
user-friendly interfaces.
1980s-90s Networked Systems Specialized OSs for computer networks;
file sharing and remote access.
Late 1990s - Early
2000s
Mobile OS Emergence of mobile OSs like iOS and
Android for touchscreen devices.
2010s-Ongoing AI Integration Integration of AI features (e.g., Siri,
Google Assistant, Alexa).

Operating System & Application
Software
Application
Software
Hardware
Operating
System
Driver Driver

Operating System & Application
Software
 Applications
 Operating System
• API: application program interface
• File management
• I/O Drivers
• Network Module
• Kernel
• Memory management
• Resource scheduling
• Program communication
• Security

Disk Operating System
 IBM Introduced DOS (Disk Operating System) in 1981. Later
many versions like MS-DOS (1982) by Microsoft were introduced.
 All DOS-type operating systems run on machines with the Intel x86
or compatible CPUs,
 DOS is a single-user, single-task operating system that are only one
program at a time can use them.

Windows Operating System
 Microsoft first introduced an operating environment named Windows in
November 1985 as an add-on to MS-DOS in response to the growing
interest in graphical user interfaces (GUIs). It was a 16 Bit OS running on
top of DOS providing Single-tasking and GUI
 Windows 3.0 (1990) and Windows Workgroup 3.11 (1992) improved the
design and were 16/32 Bit OS. Windows 3.1 had Internet Explorer browser
as a part of the OS.
 Later came Windows 95 (1995), Windows 98 (1998) and Windows (2000)
which were 32 Bit OS and used File System and supported DOS also.

Unix
 Unix is a multi-user, multi-tasking operating system.
 It can have many users logged into a system at same time.
 It keeps each process and user separate and to regulate access to system
hardware, including CPU, memory, disk and other I/O devices.
 First Version was created in Bell Labs in 1969.
 Some of the Bell Labs programmers who had worked on this project was
designed and implemented the first version of the Linux File System.
 It is one of the most effective operating systems ever created, with numerous
offshoots and a wide-reaching effect on the computing and electronics industries.
 Its main advantages include stability, interoperability, and portability across
multiple heterogeneous environments and devices.

Unix
 brief history:
• Multics (1964) for mainframes
• Unix (1969)
• K&R
• Linus Torvalds and Linux (1992)
 key Unix ideas:
 written in a high-level language (C)
 virtual memory
 hierarchical file system; "everything" is a file
 lots of small programs that work together to solve larger problems
 security, users, access, and groups
 human-readable documentation included

Linux
 What is Linux
• Linux is a Advanced Unix-type operating system originally created by
Linus Torvalds with the assistance of developers around the world.
• It originated in 1991 as a personal project of Linus Torvalds, a Finnish
graduate student. while studying computer science at University of Helsinki
• The Kernel version 1.0 was released in 1994 and today the most recent
stable version is 2.6.9
• Developed under the GNU General Public License , the source code for
Linux is freely available to everyone.

Linux
 Linux: A kernel for a Unix-like operating system.
 commonly seen/used today in servers, mobile/embedded devices, ...
 GNU: A "free software" implementation of many Unix-like tools
 many GNU tools are distributed with the Linux kernel
 distribution: A pre-packaged set of Linux software.
 examples: Ubuntu, Fedora
 key features of Linux:
 open source software: source can be downloaded
 free to use
 constantly being improved/updated by the community

Linux
 Things you can do in Linux
 Load the course web site in a browser
 Install and play games
 Play MP3s
 Edit photos
 IM, Skype

Linux
 LINUX Distributions
 Mandrake: http://www.mandrakesoft.com/
 RedHat: http://www.redhat.com/
 Fedora: http://fedora.redhat.com/
 SuSE/Novell: http://www.suse.com/
 Debian: http://www.debian.org/
 Ubuntu: http://www.ubuntu.org/

Thank you
@Eng.Abdulahi M. Adan

UNIX/LINUX Structure

UNIX/LINUX Structure
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
componen.
• Shell - An interface to kernel, hiding complexity of kernel's
functions from users. Takes commands from user and executes
kernel's functions.
• Utilities/Programs - Utility programs giving user most of the
functionalities of an operating systems.

UNIX/LINUX File System

Unix/Linux File System
 The Unix file system looks like an inverted tree structure.
 You start with the root directory, denoted by /, at the top and work
down through sub-directories.

Windows Vs. Linux File System
• In Microsoft Windows, files are stored in folders on different data drives like
C: D: E:
• But, in Linux, files are ordered in a tree structure starting with the root
directory.
• This root directory can be considered as the start of the file system, and it
further branches out various other subdirectories. The root is denoted with
a forward slash '/'.
• A general tree file system on your UNIX may look like this.

Windows Vs. Linux: Users
There are 3 types of users in Linux.
• Regular:- A regular user account is created for you when you install
Ubuntu/Santos on your system. All your files and folders are stored in /
home/ which is your home directory.
• Administrative(root):- another user account called root is created at the
time of installation. The root account is a super user who can access
restricted files, install software and has administrative privileges.
• Service:- Linux is widely used as a Server Operating System. Services such
as Apache, Squid, email, etc. have their own individual service accounts.
Having service accounts increases the security of your computer. Linux can
allow or deny access to various resources depending on the service.

Windows Vs. Linux: File Name Convention
• In Windows, you cannot have 2 files with the same name
in the same folder. See below -

Windows Vs. Linux: File Name Convention
 While in Linux, you can have 2 files with the same name
in the same directory, provided they use different
cases.

Windows Vs. Linux: Key Differences

Basic Features of Linux OS
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.

Basic Features of Linux OS
• 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.

Linux Advantages
1.Low cost: You don’t need to spend time and money to obtain licenses since
Linux and much of its software come with the GNU General Public License.
2.Stability: Linux doesn’t need to be rebooted periodically to maintain
performance levels. It doesn’t freeze up or slow down over time due to memory
leaks and such.
3.Performance: Linux provides persistent high performance on workstations
and on networks. It can handle unusually large numbers of users
simultaneously, and can make old computers sufficiently responsive to be
useful again.
4.Network friendliness: Linux was developed by a group of programmers over
the Internet and has therefore strong support for network functionality.

Linux Advantages
5.Flexibility: Linux can be used for high performance server applications,
desktop applications, and embedded systems. You can save disk space by only
installing the components needed for a particular use. You can restrict the use of
specific computers by installing for example only selected office applications
instead of the whole suite.
6.Security: Linux is one of the most secure operating systems. “Walls” and
flexible file access permission systems prevent access by unwanted visitors or
viruses.
7.Open Source: If you develop software that requires knowledge or
modification of the operating system code, Linux’s source code is at your
fingertips. Most Linux applications are Open Source as well.
8.Fast and easy installation 9.Full use of hard disk 10.Multitasking

How Linux
Multiple Operating System
 Multi-Boot system
 Generally multi-boot system boots into any one OS at a time.
 Virtualization software like VMware can be used to run multiple
instances of OSs simultaneously on the same physical machine.

How Linux
Boot Loader
 Booting is a process that starts operating systems when
the user turns on a computer system.
 A boot sequence is the initial set of operations that the
computer performs when it is switched on.
 The bootloader typically loads the main operating
system for the computer.

Thank you
@Eng.Abdulahi Mohamed

Linux Operaring System chapter one Introduction.pptx

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