Unix Presentation

What is an Operating System

• An operating system (OS) is a program that allows you to interact with the computer -- all of the software and hardware on your computer

• Basically, there are two ways to interact with the computer

1. command-line 2.Graphical User Interface (GUI)

3

History of Unix

• originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie,Brain Kernighan,etc..

• The Unix operating system was first developed in Assembly language, but by 1973 had been almost entirely recoded in C,

Unix Architecture

• kernel: The kernel is the heart of the operating system. It interacts with hardware and most of the tasks like memory management, tash scheduling and file management.

• Shell: The shell is the utility that processes your requests. When you type in a command at your terminal, the shell interprets the command and calls the program that you want. The shell uses standard syntax for all commands. C Shell, Bourne Shell and Korn Shell are most famous shells which are available with most of the Unix variants.

Shells

• An interface between the Linux system and the user

• Used to call commands and programs• An interpreter• Powerful programming language

– “Shell scripts” = .bat .cmd EXEC REXX• Many available (bsh; ksh; csh; bash; tcsh)

What is Linux

In Sept 1991, Linus Torvalds, a second year student of Computer Science at the University of Helsinki, developed the preliminary kernel of Linux, known as Linux version 0.0.1

Linux v/s Unix• UNIX Operating System Names• A few popular names:• HP-UX• IBM AIX• Sun Solairs• Mac OS X• IRIX• Linux Distribution (Operating System) Names• A few popular names:• Redhat Enterprise Linux• Fedora Linux• Debian Linux• Suse Enterprise Linux• Ubuntu Linux

Common Things Between Linux & UNIX

• Both share many common applications such as:• GUI, file, and windows managers (KDE, Gnome)• Shells (ksh, csh, bash)• Various office applications such as

OpenOffice.org• Development tools (perl, php, python, GNU

c/c++ compilers)

Unix File System Basics

• Linux files are stored in a single rooted, hierarchical file system– Data files are stored in

directories (folders)– Directories may be

nested as deep as needed

Directories

User home directories

Data files

root

Naming Files

• Files are named by– naming each containing

directory– starting at the root

• This is known as the pathname

/etc/passwd

/home/neale/b

Features of Unix

• multi-usermore than one user can use the machine at a time supported via terminals (serial or network connection).

It does this by time-slicing the computer processor at regular intervals between the various users.

• multi-taskingmore than one program can be run at a time

• hierarchical directory structureto support the organisation and maintenance of files

Advantages of Unix over Windows

• Security UNIX is considered 'more secure' while WINDOWS is considered 'less secure'.

• Open Source Linux is an open source we can get over internet. It’s source code is avialable we can change it according to our requirement.

• Free of Cost• Free from Virus

Questions???

Thank You