Draw the architecture of Unix Operating System and explain the components of Operating System.

The main concept that unites all versions of UNIX is the following four basics −

Kernel: The kernel is the heart of the operating system.

•   It interacts with hardware and most of the tasks like memory management, task scheduling and file management.

• It is a collection of program and routine written in C
• When the system is booted the kernel gets loaded into memory and communicate directly with hardware.

Function  of Kernel

• Three major tasks of kernel:

1. Process Management

2. Device Management

3. File Management

• Three additional Services for Kernel:

1.  Virtual Memory

2. Networking

3. Network File Systems

• Experimental Kernel Features:

1. Multiprocessor support

2.  Lightweight process (thread) support

• 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.
• The shell invoke a command line prompt which is usaually $ or % where the user can type a unix command
• The bourne shell(sh) is the widely used and popular shell

• Commands and Utilities: There are various command and utilities which you would use in your day to day activities. cp, mv, cat and grep etc. are few examples of commands and utilities. There are over 250 standard commands plus numerous others provided through 3rd party software. All the commands come along with various optional options.
• Command utilities or system utilities also include server program called daemons(which provide remote network and administration services)
• Files and Directories: All data in UNIX is organized into files. All files are organized into directories. These directories are organized into a tree-like structure called the file system.

• When you work with UNIX, one way or another you spend most of your time working with files. This would teach you how to create and remove files, copy and rename them, create links to them etc.

​​​​​​​In UNIX there are three basic types of files −

• Ordinary Files − An ordinary file is a file on the system that contains data, text, or program instructions.
• Directories − Directories store both special and ordinary files. For users familiar with Windows or Mac OS, UNIX directories are equivalent to folders.

• Special Files − Some special files provide access to hardware such as hard drives, CD-ROM drives, modems, and Ethernet adapters. Other special files are similar to aliases or shortcuts and enable you to access a single file using different names.