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.
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.
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.
Command – It is a instruction given by a user telling a computer to do something, such as to run a program.
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 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.
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.