# Day 3:LINUX in a nutshell

### LINUX

Linux is a free open-source software operating system, developed by Linus Torvalds. Linux is one of the most popular operating systems. It is an OS that is reliable, and secure.

* **Open source:** Linux operating system source code is available freely and for enhancing the capability of the Linux OS, several teams are performing in collaboration.
    
* **Multi-user:** Linux OS can also be defined as a multi-user system. It means more than one user can use the resources of the system such as **application programs, memory,** or **RAM** at the same time.
    

### Flavors of LINUX

RHEL

Ubuntu

Debian

Amazon Linux

CentOS

### Linux Architecture

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689614319185/2dfadc03-7da0-43d8-9b08-03a2097f4123.png align="center")

The architecture of a Linux System consists of the following layers −

* **Hardware layer** − Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).
    
* **Kernel** − It is the core component of the Operating System, and interacts directly with hardware.
    
* **Shell** − An interface to the kernel, from users. The shell takes commands from the user and executes the kernel's functions.
    
* **Application/Utilities** − Utility programs that provide the user with most of the functionalities of an operating system.
    

### Linux Folder Structure

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689615823507/a9f2f0d4-0ba9-4f7e-ae7f-5b2f1b7a2156.jpeg align="center")

### Linux Commands

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689615860732/528240a4-d56c-44ac-85e4-eac8252e8b74.jpeg align="center")

I am posting Day 2 to 3 Task from #90daysofdevops challenge.

# Day 2 Task: Basics Linux command

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610489869/199cedfa-648f-4286-a75a-06d5a3ff49f3.png align="left")

Task: What is the Linux command to Check your present working directory?

List all the files or directories including hidden files.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610679757/ad9baf0d-e547-42ed-801c-6c6bd3fa66c0.png align="left")

Create a nested directory A/B/C/D/E

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610708310/23a3ddbe-dc53-4ccf-b0dc-f428685181b8.png align="left")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610743402/8db8b6de-b6d1-42af-a317-f4d3361e13fc.png align="left")

# **Task 3**

# Day 3 Task: Basic Linux Commands

Task: What is the Linux command to To view what's written in a file?

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610970906/2d43cc2c-3680-42c8-b20d-973d3323acf4.png align="left")

To change the access permissions of files.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689610994227/1ea21c98-a04c-4278-9209-9f298ebd22ce.png align="left")

To check which commands you have run till now.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611205340/d39a85d5-5f91-4750-9c32-ae3d60046629.png align="left")

To remove a directory/ Folder.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611235170/fe4ed626-8211-4080-bdda-f6ce486d5b7d.png align="left")

To create a fruits.txt file and to view the content.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611284777/9b1aa41b-720e-4c75-944b-6b46ceaf7663.png align="left")

Add content in devops.txt (One in each line) - Apple, Mango, Banana, Cherry, Kiwi, Orange, Guava.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611342201/75f2c50c-77ed-4628-b1fb-4eebf36f4ee9.png align="left")

To Show only the top three fruits from the file.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611550372/0717479e-8111-4ccf-a3eb-a7acd75d3e0d.png align="left")

To Show only the bottom three fruits from the file.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611596924/8d3ccf1e-7114-4c7f-adb9-8f0c8ff4919c.png align="left")

To create another file Colors.txt and to view the content. Add content in Colors.txt (One in each line) - Red, Pink, White, Black, Blue, Orange, Purple, [Grey.](http://Grey.To)

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611629045/478288f3-d120-48c1-b295-39d62dd2e930.png align="left")

[To](http://Grey.To) find the difference between fruits.txt and Colors.txt files.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1689611682870/b4859a02-cd99-42bd-9a2a-e0c8dbff5f8e.png align="left")

Thank you for giving your precious time for reading this blog/article.

Happy Learning!