What is the Unix Operating System : Architecture & Its Properties

A computer system contains hardware and software components. We can install and use many types of software on our computers. The software’s on the computer is distinguished as two types – System software and application software. The system software is specially designed to provide a platform for other software on the computer. Application Softwares are the user-defined software that works on the system software. An operating system is an example of system software. Application software can be customized by the users, whereas it is not possible for the system software. Example of the application software is File viewer, spreadsheet, games, etc. Unix is an operating system that comes under the category of system software.

What is the Unix Operating System?

To control and manage computer hardware, software resources, and Operating system is required for the computer. The operating system acts as the intermediate between hardware and the user-defined application software. Unix is a multitasking, multiuser operating system.

It was developed at Bell Labs research center during the 1970s by Ken Thompson, Dennis Ritchie, and others. This operating system was specially designed to work on large mainframe systems. 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.

This os is used on various devices such as PCs, Tablets, Mobile devices, etc… It played an essential role in the development of the Internet and networking.

The Architecture of Unix Operating System

Unix has a graphical user interface similar to the Windows operating system that makes it easy for navigation and a good supportive environment. The internal design view of this operating system can be known from its architecture.

Unix Architecture
Unix Architecture

The architecture of this operating system is four layered. It consists of Hardware, Kernel, System Call interface(shell) and application libraries/tools, utilities, etc…The kernel controls the hardware of the computer and resides at the core of the architecture. System calls acts as the interface between the kernel and other libraries. These libraries include general functions and built on top of the system calls. Shell is a special application that provides an interface to the other applications of the architecture.



For this operating system, Kernel is the central core that interacts directly with the hardware of the system. The main functions of Kernal are-

  • Computer hardware such as memory, disc, printers, etc.. are controlled by the kernel.
  • The kernel schedules the processes, control and executes various user-defined tasks.
  • Manages the data storage and control the computer accesses by several users.
  • The kernel is composed of several sub-components such as configurations including boot code, device drivers to control hardware, header files.


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.


Some of the major categories of commands used by the Unix operating system are – ‘sh’ – shell commands providing a primary user interface, ‘utilities’ forming the core toolkit of Unix commands includes sub-categories such as system utilities supporting administrative tools and User utilities for environment management tools.

It also has commands for general purpose applications such as document-formatting and typesetting. Some Unix systems also include packages such as TeX and Ghostscript. This system also provides the facility for producing device-independent simple vector plots. It also supports inter-system communication as well as inter-user communication.


From the time of its development, Unix has been adopted by many companies. It still plays a big role in many data centers and research labs. Some of the properties of Unix that make it so preferable over other systems are-

  • Multiuser accessing – Multiple users can work on the system simultaneously by connecting through a point known as terminal.
  • Multi-tasking-It provides the facility to run multiple programs or processes by multiple users on one system.
  • Portability – It provides the flexibility to be used on multiple hardware architectures. As it uses a high-level language, it is easy to comprehend and modify the Unix code according to the hardware architecture of the computer. Thus to work on new hardware architecture, the user has to simply modify the Unix code and run on the system.
  • Processes– Files are the collection of data created by the user. It includes documents, programming instructions, etc…Processes are the executions of the programs or files. Unix follows the hierarchical file structure that starts with a root directory followed by the subdirectories ending with the file name.
  • Communication – Requests and commands given by the user are carried out by the kernel and shell together. The user communicates with the system using Shell. It also provides inter-system communication through UUCP. This operating system also obeys the TCP/IP protocol.
  • It also provides easy maintenance of the files
  • This operating system provides Pipes and Filters to the user to design complex programs from simple programs.
  • It provides a wide variety of tools for software development and software maintenance.
  • It is very popularly used on Desktop computers, laptops, mainframes, and other computing hardware.

Types of Unix Operating Systems

Unix gives the user the flexibility to modify the  Unix code according to their requirements. Thus it is easy to port the Unix code on different types of hardware. The freely available source code of this operating system and its portability feature lead to various Unix like operating systems. Some of the popular Unix like operating systems are Solaris, Darwin, AIX, HP-UX, FreeBSD, NetBSD, Xenix, IRIX, Tru64, macOS, etc…

The Unix trademark is owned by “The Open Group”. This group provides the certification programs to an operating system to be officially certified as Unix.

Thus, this article discusses an overview of the UNIX operating system and what kind of operating system is UNIX. The Unix architecture has seen various developments in its structure from the time of its development. Today this operating system preferred by many companies such as IBM, Apple.Inc, Microsoft, Silicon Graphics, Oracle Corporation, and many other opensource projects and companies. What is a shell in Unix operating system?