What are the components and functions of the UNIX OS?

UNIX is one of the most popular operating systems on multi-user systems. Actually, it originated as a single-user system. It has limited structuring.

UNIX OS consists of two separable parts which are as follows −

  • System programs.

  • Kernel.

Now, let us see the architecture of UNIX.

Unix Architecture

Unix operating system architecture is divided into four layers as given below −

  • Hardware

  • Kernel

  • System call or shell

  • Application programs

Given below is the diagram of UNIX architecture showing all the layers −


It is a part of the operating system. It interacts directly with the hardware of the computer with the help of a device that is built into the kernel.

Functions of Kernel

The functions of the kernel are as follows −

  • Memory management

  • Controlling access to the computer.

  • Maintaining the file system.

  • Handling interrupts.

  • Handling errors.

  • Performing input and output services.

  • Kernel allocates the resources of the computer to the users.

  • The kernel is the most important part of the Architecture of UNIX OS.


It is a software program that acts as a mediator between the kernel and the user. It reads the commands and interrupts by sending requests to execute a program. So, the shell is known as a command interpreter.

It contains almost 100 system calls and tells the kernel to carry out various tasks for the program. These tasks are as follows −

  • Opening a file.

  • Writing a file.

  • Obtaining information about a file.

  • Executing programs.

  • Terminating a process.

  • Changing the priority of processes.

  • Getting the time and date.


The hardware is nothing but the parts of a computer that includes clocks, timers, devices, parts etc. in the Unix OS Architecture.

Components of UNIX

The components of UNIX operating system are as follows −

  • Kernel − It is the main part of the operating system.

  • Shell − It is a command user interface that is helpful in interpretation. For example- system calls.

  • User − It refers to a person who is interacting with the Unix Operating system. For example, humans.

  • System Hardware − It is a peripheral containing input and output devices. For example- Keyboard and monitor.

Functions of UNIX

The functions of UNIX operating system are as follows −

  • Effective Optimization of resources − It optimizes the task of effective utilization of resources.

  • Memory Management − This includes swapping of pages in memory.

  • Process Management − It involves scheduling of processes. For example, the FIFO scheduling algorithm.

  • Maintaining file system − It maintains files by removing junk files.

  • Handling interrupt − It handles the signals caused by hardware. For example, if some process demands an input device so it produces an interrupt.