Introduction to UNIX
Unix as an Operating System is truly the base of all Operating Systems like Ubuntu, Solaris, POSIX, etc. It is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others.
In this Blogpost, you will be able to understand the basic concepts of UNIX and will cover below topics:
What is Unix Operating system
History of Unix
Unix Architecture
Features of Unix
What is Unix OS & its History?
The operating system or the kernel is the computer programs that allocate the system resources and coordinate all the details of the computer's internals. The Unix operating system is a set of programs that act as a link between the computer and the user. Users communicate with the kernel through a program known as the shell. The shell is a command line interpreter; it translates commands entered by the user and converts them into a language that is understood by the kernel.
Lets see some brief points & history about UNIX.
Unix was originally developed in 1969 by a group of AT&T employees Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna at Bell Labs.
The main focus that was brought by the developers in this operating system was the Kernel.
Unix was considered to be the heart of the operating System. So there are various Unix variants available in the market. Solaris Unix, AIX, HP Unix and BSD are a few examples. Linux is also a flavor of Unix which is freely available.
Several people can use a Unix computer at the same time; hence Unix is called a multiuser system.
A user can also run multiple programs at the same time; hence Unix is a multitasking environment
Unix System Architecture
Now lets see System Architecture of UNIX OS.
The main concept that unites all the versions of Unix is the following four layers:
Layer-1: Hardware It consists of all hardware related information of your UNIX machine.
Layer-2: 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 management are done by the kernel.
Layer-3: Shell Commands and Utilities 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 the most famous shells which are available with most of the Unix variants. Commands and Utilities : There are various commands and utilities which you can make use of in your day to day activities. cp, mv, cat and grep, etc. are few examples of commands and utilities. All the commands come along with various options. Files and Directories − All the data of Unix is organized into files. All files are then organized into directories. These directories are further organized into a tree-like structure called the filesystem.
Layer-4: Application Layer It is the outermost layer that executes the given external applications.
Features of Unix
There are several important features of Unix, lets point out some main features below:
It was the first operating system that was written in a high-level language (C Language). This made it easy to port to other machines with minimum adaptations.
It is a multi-user system where the same resources can be shared by different users.
It provides multi-tasking, wherein each user can execute many processes at the same time.
It provides a hierarchical file structure which allows easier access and maintenance of data.
Unix has built-in networking functions so that different users can easily exchange information.
Unix functionality can be extended through user programs built on a standard programming interface.
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