Unix system : the operating system of Unix is a set of programs that will act as a link between the user and the computer the computer programs that are allocated to the system resources and co-ordinate all the details of the computers internals is called the operating system or kernel.
Users communicate with the kernel with the program known as the shell the shell is a command line interpreter it translate commands entered by the user and convert them into a language that is understood by the kernel.
Unix pause originally developed in 1969 by a group of AT&t employee at bells lab introducing Ken Thompson Dennis Ritchie Douglas MC llroy, and Joe osanna.
There are various Unix variants available in the market.
A user can also run multiple programs at the same time hence Unix is called multitasking.
The main concept that aunties all versions of Unix are on the following four basis
Kernel :
the kernel is the essential centre of the computer operating system the core that provides basic services for all other parts of the operating system a synonym is nucleus. Can be contrasted with the shell where the outermost part of an operating system that interacts with user commands
Shell :
the shell is the utility that process your request when you type in a command at your terminal the shell interpret 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 shell 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 and grep are few examples of command and utilities there are over 250 standard commands plus numerous other provided through third party software all the commands come with various optional options.
Files and directories :
all data in UNIX is organised into files all files are organised in two directories these directories are organised into a tree like structure called the file system.