Here is a basic block diagram of a UNIX 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.
- 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.
- Commands and Utilities: There are various command and utilities which you would use in your day to day activities. cp, mv, cat andgrep 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.
- 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 filesystem.
System Bootup
If you have a computer which has UNIX operating system installed on it, then you simply need to turn on its power to make it live.
As soon as you turn on the power, system starts booting up and finally it prompts you to log into the system, which is an activity to log into the system and use it for your day to day activities.
