Introduction

Welcome to Day 2 of our 90-day DevOps journey! In today's blog, we will learn about basics of Linux operating system. we'll dive deeper into Linux, exploring its core components, architecture, essential commands, and more basic concepts crucial for DevOps daily-to-daily tasks.

What is Linux?

Linux is an open-source operating system kernel originally developed by Linus Torvalds in 1991. It is the core of many Linux distributions (distros) like Ubuntu, Debian, CentOS, and Fedora. Known for its stability, security, and flexibility, Linux powers everything from servers and supercomputers to embedded devices and smartphones (Android is based on the Linux kernel).

Why Linux?

Linux is a powerhouse in the world of operating systems, and its widespread adoption in various domains—from personal computers to enterprise servers—raises the question: Why Linux? Below, we explore the key reasons why Linux is a preferred choice for many users and organizations.

Open Source and Free

Example: Ubuntu, a popular Linux distribution, is free to download and use. Users can also access and modify its source code to fit their needs.
Stability and Reliability

Example: Many web servers, including those for major companies like Google and Facebook, run on Linux due to its ability to handle high loads and maintain stability over long periods.
Security

Example: The Apache web server on Linux benefits from regular updates and community-driven security patches, making it a secure choice for hosting websites.
Flexibility and Customization

Example: Distributions like Arch Linux allow users to build their system from the ground up, installing only the software they need and customizing it to their exact specifications.
Performance

Example: Embedded systems, like those in routers and IoT devices, often run on Linux due to its minimal resource requirements and high efficiency.

Architecture of Linux

Linux follows a monolithic kernel architecture where the kernel provides core functionality directly to applications and drivers. Key components include:

Kernel: Core of the operating system managing hardware, memory, and processes.

Shell: Interface for users to interact with the kernel via command-line interpreters like Bash.
Filesystem: Organizes data into files and directories, supporting various filesystem types (e.g., ext4, etx2).
Processes: Running instances of programs managed by the kernel.

Components of the Linux File System

The Linux File System is structured hierarchically, starting from the root directory (/). Key directories include:

/bin: Essential user binaries (commands) like ls, cp, mv.
/etc: Configuration files for system-wide settings.
/home: Home directories for users.
/var: Variable files like logs and databases.
/proc: Virtual file system providing kernel and process information.

Basic Linux Commands

ls - Lists files and directories in the current directory.

  ls
  # Example: Listing contents of the current directory

cd - Changes the current directory.

  cd /path/to/directory
  # Example: Changing to the /var/log directory
  cd /var/log

pwd - Prints the current working directory.

  pwd
  # Example: Showing the current directory path

mkdir - Creates a new directory.

  mkdir new_directory
  # Example: Creating a directory named "projects"
  mkdir projects

rmdir - Removes an empty directory.

  rmdir empty_directory
  # Example: Removing an empty directory named "old_folder"
  rmdir old_folder

rm - Removes files or directories.

  rm file_or_directory
  # Example: Removing a file named "old_file.txt"
  rm old_file.txt
  # Example: Removing a directory and its contents
  rm -r old_directory

cp - Copies files or directories.

  cp source destination
  # Example: Copying a file "file.txt" to the "backup" directory
  cp file.txt backup/
  # Example: Copying a directory and its contents
  cp -r source_directory backup/

mv - Moves or renames files or directories.

  mv old_name new_name
  # Example: Renaming a file from "oldname.txt" to "newname.txt"
  mv oldname.txt newname.txt
  # Example: Moving a file to another directory
  mv file.txt /path/to/destination/

touch - Creates an empty file or updates the timestamp of an existing file.

  touch filename
  # Example: Creating an empty file named "newfile.txt"
  touch newfile.txt

cat - Concatenates and displays the content of files.

  cat file
  # Example: Displaying the content of "file.txt"
  cat file.txt

more - Views file content one screen at a time.

  more file
  # Example: Viewing the content of "file.txt" one screen at a time
  more file.txt

less - Views file content with backward and forward navigation.

  less file
  # Example: Viewing the content of "file.txt" with navigation
  less file.txt

head - Displays the first few lines of a file.

  head file
  # Example: Displaying the first 10 lines of "file.txt"
  head file.txt

tail - Displays the last few lines of a file.

  tail file
  # Example: Displaying the last 10 lines of "file.txt"
  tail file.txt

These are some basic commands you will use in Linux daily. If you have any issues with any Linux command, use the man command to get complete information about it.

Syntax

man [command]

Examples

View the manual page for the ls command:
```
 man ls
```
This will display the manual for the ls command, which lists the files and directories in the current directory.

Well, congratulations! We are making great progress in the DevOps challenge and have unlocked the realm of Linux. These basic commands are the main way to interact with Linux. Get yourself familiar with them, and I'll see you in the next blog as we continue this exciting journey.

Beginner's Guide to Basic Linux Commands: Day 2

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