Day 1 (Linux for DevOps)

What is Linux?

Linux is a family of open-source Unix-like Operating systems based on the Linux Kernel, an operating system kernel first released on September 17, 1991, by Linux Torvald. Linux Is typically packaged as a Linux distribution, which includes the kernel and supporting system software and libraries, many of which are provided by the GNU project.

Open - source

Open-source software is a software with source code that anyone can insert, modify, and enhance. Open-source permits others to make modifications to source code and incorporate changes into their own project.

They encourage computer programmers to access, view, and modify open-source software whenever they like.

History of Linux

• Linus Torvalds identified few issues with Unix.

• Linus Torvalds started developing his own OS by using MINUX OS.

• Linus Torvalds release Linux OS free of cost

• Linus Torvalds provided Linux OS code also on the internet.

• People and companies downloaded source code of Linux OS, and they modified according to their requirements and released into market with their brand names.

• As companies released their own Linux OS, we can see several distributions of Linux OS

  Ex: Ubuntu ; CentOS ; RedHat ; Fedora ; SUSE ; KALI ; Debian etc.…

  There are 200+ Linux distributions available in the market.

Architecture

The architecture of a Linux System consists of following layers -

1. Hardware Layer: Hardware consists of all peripheral devices (RAM/HDD/CPU etc.)

2. Kernel: It is the core component of OS, interact directly with hardware, provides low level services to user level components.

3. Shell: an interface to kernel, hiding complexity of kernel, functions from users. The shell takes commands from the user and executes kernel’s functions.

4. Application/ Utilities: Applications or utilities programs that provide the user most of the functionalities of an Operating system.

Features of Linux

Following are some important features of Linux Operating system.

1. Portable: Portability means software can work on different types of hardware in same way. Linux Kernel and application programs supports their installation on any kind of hardware platform.

2. Open Source: Linux source code is freely available, and it is community- based development project. Multiple teams work in collaboration to enhance the capability of Linux Operating system, and it is continuously evolving.

3. Multi- User: Multiple users can access system resources like memory, ram, applications programs at same time.

4. Multiprogramming: Linux is multiprogramming system means multiple applications can run at same time.

5. Hierarchical file system: Linux provides a standard file structure means in which system files/ user files are arranged.

6. Shell: Linux provides a special interpreter program which can be used to execute commands of the operating system. It can be used to do various types of operations, call application programs etc.

7. Security: Linux provides user security using authentication features like password protection/ controlled access to specify files/ enterprise of data.