Some Linux Definition

Linux

Linux

Some basic definition which I wanted to remember always, in my early stages, whereas which is very important to understand if someone will like to learn Unix / Linux with basic concepts rather then just a knowing.

  1. Kernel – It is the core of the system. It controls all the tasks, schedules all the process and carries out all the functions of the operating system. It is the code that controls the interface between user programs and hardware devices. Please always remember it is not an operating system.
  2. Shell – It is the command interpreter of the operating system. It accepts commands from the user and analyzes and interprets these commands. Hence shell acts as a middle man between the Kernel and the users of operating system.
  3. Command – It is a instruction given by a user telling a computer to do something, such as to run a program.
  4. Program – It is an executable file usually files that are stored in one of the bin directory.

Have figured out these definitions from numerous areas.  Share more if you feel like to include in the list.

PATH in Linux

Path

Path via Clearly Creative

Path is an important area to understand when it comes to Unix / Linux.

What is PATH ?

It is an enviornmental variable in Unix / Linux that tells the shell which directories to search for executable files in response to commands issued by the user. Enviornmental variables are items for which values can be changed.

There are two types of PATH

1. Absolute Path

An abosolute path is easily recognized from the leading forward slash “/”. You start at the top level directory and continue down.

for e.g cd /boot/grub

2. Relative Path

A relative path doesn’t have a preceeding slash, usage of relative path is when you start from directory below the top level. This is dependent on where you are in the filesystem.

for e.g. While being in user’s home directory, going to /user/music you just type cd music

Note. My words are covered with my research therefore some might contain to some reference.

File Types & I/O Rediction

I/O

I/O

I was has having problem in recognizing file types in my studies, therefore to learn I searched and read few documents and found these types under Unix / Linux:-

  • (-) – ASCII/ordinary files
  • (d) – Directories
  • (c) – Character Special Files
  • (b) – Block Special Files
  • (p) – FIFO Files or Pipes

Further everything which carry down with Input Output Redirection over entire Unix / Linux is followed by

  • Standard Input – “0” – Keyboard
  • Standard Output – “1” – Terminal / Display
  • Standard Error – “2” – Terminal / Display

Note:- It will be pleasure if someone would like to contribute more to this post

Some History Points of Unix / Linux

LINUX LINUS TORVALDS

LINUX LINUS TORVALDS

As I entered in the world of open-source by adopting Unix / Linux on my passion list, few basic things which I highlighted in the beginning were written down on a piece of paper. Thought to pool it down for my memories.

Unix / Linux

  • Minix – Unix like operating system before Linux
  • Unix – developed by Bill Labs
  • BSD – Popular distribution from University of California at Barkley
  • Main Purpose – Multitasking system for minicomputers
  • Linux originally developed by Linux Torvalds, began work in 1991 as a student in Finland at University of Helsinki
  • Linux Kernel – Lowest level core component is still maintained by Linus Torvalds
  • March 1994 – Version 1.0 finally was appeared.
  • Text Formatter (TeX) was by Donald Knutn
  • Linux is an inexpensive, efficient and robust system.

Hope you have got the vision of how basically we all started, like I have done. Share your experience for more fun.