An Introduction to Unix

An Introduction to Unix

by Sanjay Nair February 17, 2018

An Introduction to Unix

  • UNIX is an OS which was developed in the 1960s and since then it has been under constant development ever since.
  • By Operating system, we intend the collection of programs which make the computer work. Unix is a stable , multiple user system for servers, desktops and laptops.
  • UNIX has a GUI similar to Microsoft Windows and it provides an easy to use environment. Knowledge of unix is essential if you are willling to use such a system or when there is no windows interface available.

Unix Types:

  • There are various versions of UNIX with some of the popular varieties being Sun Solaris, GNU/Linux and MacOS X

UNIX Operating System

  • The UNIX is made up of 3 parts: the kernel, the shell and the programs.

The Kernel:

  • The kernel is the hub of the OS:
  • The kernel allocates time and memory to various programs and handles communications in response to system calls.

The shell

  • The shell is the biggest interface between the user and the kernel.
  • When a user logs in, the program checks for the username and password, and then initiates another program termed as the shell.
  • The shell is basically a command line interpreter(CLI) which interprets the commands the user types in and manages to carry them out.
  • The commands are programs themselves that on terminations gives the user another prompt.
  • The expert user can customise his/her own shell and users can use different shells within the same machine.
  • The tcsh shell has features to help user input commands.

Name completion

  • By typing the name of a command and by pressing the Tab key , the tcsh shell displays the rest of the name automatically.
  • In UNIX everything is a file or a process
  • A process is an executing program which is identifed by a unique PID(Process Identifier)
  • The collection of data is a file. The file is created by users using a text editor, running compilers etc.

 

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