UNIX OPERATING SYSTEM

UNIX is a powerful Operating System initially developed by Ken Thompson, Dennis Ritchie at AT&T Bell laboratories in 1970.Unix is written using a C programming language. It is the first portable operating system and is being used on numerous platforms. It provides various advanced security features.

FEATURES OF UNIX OS

Multitasking: A UNIX operating system is a multitasking operating system that allows you to initiate more than one task from the same terminal so that one task is performed as a foreground and the other task as a background process.

Command Structure: UNIX commands are easy to understand and simple to use. Example: “cp”, mv etc. While working in the UNIX environment, the UNIX commands are case-sensitive and are entered in lower case.

File Security and Protection: Being a multi-user system, UNIX makes special consideration for file and system security. UNIX has different levels of security using assigning username and password to individual users ensuring the authentication, at the level providing file access permission viz. read, write and execute and lastly file encryption to change the file into an unreadable format.

Communication: In UNIX, communication is an excellent feature that enables the user to communicate worldwide. It supports various communication facilities provided using the write command, mail command, talk command, etc.

Accounting: UNIX keeps an account of jobs created by the user. This feature enhances the system performance in terms of CPU monitoring and disk space checking. It allows you to keep an account of disk space used by each user, and the disk space can be limited by each other.

UNIX Tools and Utilities: UNIX system provides various types of tools and utilities facilities such as UNIX grep, sed and awk, etc. Some of the general-purpose tools are compilers, interpreters, network applications, etc. It also includes various server programs which provide remote and administration services.

Open Source: UNIX operating system is open source it means it is freely available to all and is a community-based development project.

Portability: This feature makes the UNIX work on different machines and platforms with the easy transfer of code to any computer system. Since a significant portion of UNIX is written in C language, and only a tiny portion is coded in assembly language for specific hardware.

Multi-user: UNIX operating system supports more than one user to access computer resources like main memory, hard disk, tape drives, etc. Multiple users can log on to the system from different terminals and run different jobs that share the resources of a command terminal. It deals with the principle of time-sharing.

UNIX ARCHITECTURE

Hardware: Hardware is the most simple and least powerful layer in the Unix Architecture. Hardware is the components that are humanly visible. Whatever hardware is connected to a Unix operating system-based machine, comes in the hardware layer.

Kernel: This is the most powerful layer of the Unix architecture. The kernel is responsible for acting as an interface between the user and the hardware for the effective utilization of the hardware. The kernel handles the hardware effectively by using the device drivers.

Shell: It is the interface between the user and the kernel. Users can interact with the shell using shell commands. Shell has two main responsibilities which include interpreting the commands given by the users and execute them using the kernel, providing programming ability to the users to write shell commands for a shell script to perform specific tasks. There are 3 types of shells in the Unix Operating system.

• Bourne Shell (sh): It is the most widely available shell on Unix OS devices across the world. This was the first shell available in the Unix OS. It is simply called a shell.
• C Shell (csh): The University of California (Berkeley) developed C Shell is another Unix shell that removes some of the obsolete features or problems from the Bourne Shell. So, it enhances the performance of the Bourne Shell.
• Korn Shell (ksh): The name of the Korn Shell is based on its creator, David Korn. This shell enhances the C shell further by removing the shortcomings of the C shell and also enhancing the user interaction of the Bourne Shell.

Applications/Application Programs: It is the outermost layer that executes the given external applications. UNIX distributions typically come with several useful applications programs as standard. For Example: emacs editor, StarOffice, xv image viewer, g++ compiler etc.

TYPES OF UNIX OS

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X. Linux in its turn is packaged in a form known as a Linux distribution. There are several Linux distributions, both free and commercial.

ISU has a campus site subscription to Red Hat Enterprise Linux (RHEL), providing access for university-owned equipment as well as personal access to students, faculty, and staff. All our clusters are running RHEL.

ADVANTAGES OF UNIX OS

• Memory usage: UNIX use less memory while running sophisticated programs. UNIX OS can handle virtual memory nicely. The virtual memory expands as more programs come into the main memory. Most of the tasks in UNIX is done by using fewer resources.
• Safe and Secure: The kernel is an interface between the user and the hardware and the Shell is an interface between the user and the kernel. So, there is no way a user can interact directly with the hardware or the kernel. Hence, Unix is highly secure. Also, Unix and Unix-based OS are considered safe from viruses. Hence, there is no need to install any external anti-virus software in Unix OS.
• Less code to execute: In GUI (graphical user interface), we sometimes need many mouse clicks to perform some specific task but in the case of UNIX we can simply write one command in CLI (command line interface) and that task is done.
• Portable: Unix is portable. This means that Unix can be installed on any computer or laptop. This is because it is developed using C language and C language is a high-performing and highly portable programming language.
• No anti-virus needed: As you know that Chrome OS, macOS, Linux, Ubuntu and android are developed by using UNIX OS. These OS are considered safe from any virus. You don’t need to install any anti-virus in newly build Chrome OS.
• Files used everywhere: All type of data is stored in files i.e. all devices and terminal are stored in files. Working with files in OS becomes fast and can be easily managed by UNIX.

IS UNIX OS STILL USED?

YES!!!…Today it’s a x86 and Linux world, with some Windows Server presence. … HP Enterprise only ships a few Unix servers a year, primarily as upgrades to existing customers with old systems. Only IBM is still in the game, delivering new systems and advances in its AIX operating system. A medium to large-scale computer system in a network that runs under Unix. Unix servers are widely used as application servers and database servers and are available from a variety of vendors, including Sun, IBM, HP and others.