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 −
Now, let us see the architecture of UNIX.
Unix operating system architecture is divided into four layers as given below −
System call or shell
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.
The functions of the kernel are as follows −
Controlling access to the computer.
Maintaining the file system.
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.
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.
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.
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.