Kirti Dahiya Os

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WHAT IS AN OPERATING SYSTEM?

An interface between users and hardware - an environment

"architecture

Allows convenient usage; hides the tedious stuff

Allows efficient usage; parallel activity, avoids wasted cycles

Provides information protectionGives each user a slice of the resources

Acts as a control program.

OPERATING SYSTEM

OVERVIEW


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ommon ys emComponents of an OS

Process Management

Main Memory Management

File Management

Secondary Memory Management

I/O System Management

Networking

Protection System

Command-Interpreter System (Shell)


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OPERATING SYSTEMOVERVIEW

1: Operating Systems Overview 4

The Layers Of

A System

Program Interface

Humans

User Programs

O.S. Interface

O.S.

Hardware Interface/

Privileged Instructions

Disk/Memory/Screen


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Performance:

1: Operating Systems Overview 5

OPERATING SYSTEM

OVERVIEWStorage

Hierarchy


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OS services


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Some examples of operating system are Microsoft Windows,

Macintosh OS X, Linux , Unix and also DOS


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What is Unix?A multi-user networked operating systemOperating System Handles files, running other programs, input/output

Looks like DOSbut more powerful

The internet was designed on it, thus networking is anintrinsic part of the system

Multi-user Every user has different settings and permissions

Multiple users can be logged in simultaneously


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History of unix

History,Bell Labs and AT&T UNIX Bell Labs and AT&T UNIX development groups develop several

version of UNIX: first edition (1969), ,seventh edition (1978,on PDP-

11/70) a version for Interdata 8/2 and VAX UNIX for a network of computers System III (1982 - first commercial version) System V based on System III(1983) System V release 2, 3, 4 (1984 - 1989) SVR4 (System V release 4; 1989 AT&T and Sun Micro

systems) 1993: AT&T becomes a phone company and sells UNIX to Novell


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Overview of Unix SystemKernel & Shell Unix/Linux is operating system (OS). Unix system is described as kernel &

shell.

Kernel is a main program of Unixsystem. it controls hard wares, CPU,memory, hard disk, network card etc.

Shell is an interface between user and

kernel. Shell interprets your input ascommands and pass them to kernel. Kernel

Shell

Userinput


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Unix directoryDirectory Structure


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Features of unixUNIX is a multi-user systemAllows many users access and share the

resources of a server computer

UNIX is a multitasking systemAllows user to execute more than one program

at a time

UNIX is a portable operating systemUsed in many computing environments


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Basic CommandsCommands su switch user

passwd change password

useradd create new user account

userdel delete user account

mount mount file system

umount unmount file system

df show disk space usage

shutdown reboot or turn off machine


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What is LinuxA fully-networked 32/64-Bit Unix-like Operating

System

Unix Tools Like sed, awk, and grep

Compilers Like C, C++, Fortran, Smalltalk, Ada

Network Tools Like telnet, ftp, ping, traceroute

Multi-user, Multitasking, Multiprocessor

Has the X Windows GUI

Coexists with other Operating Systems

Runs on multiple platforms

Includes the Source Code


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HistoryLinus Torvalds created it

with assistance from programmers around theworld

first posted on Internet in 1991

Linux 1.0 in 1994; 2.2 in 1999

Today used on 7-10 million computers

with 1000s of programmers working to enhanceit
http://www.computerworld.com/home/features.nsf/all/980817linushttp://www.computerworld.com/home/features.nsf/all/980817linus


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The Linux Kernel Linux 0.01 (May 1991) had no networking, ran only on

80386-compatible Intel processors and on PC

hardware, had extremely limited device-drivesupport, and supported only the Minix file system.

Linux 1.0 (March 1994) included these new features: Support for UNIXs standard TCP/IP networking protocols BSD-compatible socket interface for networking programming Device-driver support for running IP over an Ethernet Enhanced file system Support for a range of SCSI controllers for high-performance

disk access Extra hardware support

This version is sufficient compatible with UNIX andmany people are interested in developing Linux under

Torvald supervision. Linux 1.2 (March 1995) was the final PC-only Linux

kernel.

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Linux 0.01The first version of Linux (Linux 0.01) has some

of features of MINIX (ex. File system), but themain differences between Linux and MINIX are:The Linux kernel uses a monolithic model, and it

has many more functions than the micro-kernel ofMINIX.

From a theoretical point of view MINIX is betterthan Linux, but from a practical point of view theperformances of Linux are better than that one ofMINIX.

Li 2 0


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Linux 2.0Released in June 1996, 2.0 added two major new

capabilities:

Support for multiple architecturesSupport for multiprocessor architectures

Other new features included: Improved memory-management code Improved TCP/IP performance

Support for internal kernel threads, for handlingdependencies between loadable modules, and for automaticloading of modules on demand.

Standardized configuration interface

Available for Motorola 68000-series processors, Sun

Sparc systems, and for PC and PowerMac systems.Linux 2.2 January 1999 improves some aspects of

Linux 2.0The last release is Linux 2.4.20 (production)

Linux 2.5.64 (development)
http://www.linuxhq.com/kernel/v2.4/20/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.5/64/index.htmlhttp://www.linuxhq.com/kernel/v2.4/20/index.html


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Conclusion

Linux is a modern, free operating system based onUNIX standards.

First developed as a small but self-contained kernelin 1991 by Linus Torvalds, with the major design goalof UNIX compatibility.

Its history has been one of collaboration by manyusers from all around the world, correspondingalmost exclusively over the Internet (software opensource).

It has been designed to run efficiently and reliably oncommon PC hardware, but also runs on a variety ofother platforms.

The core Linux operating system kernel is entirelyoriginal, but it can run much existing free UNIXsoftware, resulting in an entire UNIX-compatible

U


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Users

Linux is an intrinsically multi-user system

Every user on the system has its ownusername and password

The root user has ultimate power to run thesystem. You should not log in as rootunlessyou really need to.

During installation, you should have beenprompted for a root password and also ausername and password for an ordinary user

account.The commandpasswdallows to change the

password.

Careful: you have to perform the program

shutdown h now before to switch off the PC


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Unix vs. LinuxAgeUnix: born in 1970 at AT&T/Bell Labs

Linux: born in 1992 in Helsinki, FinlandSun, IBM, HP are the 3 largest vendors of

UnixThese Unix flavors all run on custom hardware

Linux is FREE! (Speech vs. Beer)Linux was written for Intel/x86, but runs on

many platforms


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