#Day4:- 90 Days DevOps Challenge @ Basic Linux Shell Scripting for DevOps Engineers.

💻What Is Kernel 😕?

The kernel is the core component of an operating system, acting as the bridge between software and hardware. 🌐🛠️

Think of it as the conductor of an orchestra, coordinating tasks and managing resources. 🎵👩‍💻

Example: In Linux, the kernel manages memory, processes, device drivers, and provides essential functionalities for programs to run efficiently. 🐧💡

So, next time you use your computer or smartphone, remember that the kernel is the unsung hero making it all possible! 🦸‍♂️💻.

🐚🐚What Is Shell🐚?

🐚 Shell is a command-line interface that acts as an intermediary between the user and the operating system. It allows users to interact with the computer by entering commands. Think of it as the "shell" that surrounds the operating system, providing access to various utilities and services.

Example: Suppose you want to list all the files in a directory. In the shell, you can use the "ls" command:

Command: ls Result: 📁📄 (Displays a list of files and directories in the current location)

With the shell, you can perform various tasks, from navigating the file system to running complex scripts, making it a powerful tool for both beginners and advanced users. 🚀🔧

🐚What is Linux Shell Scripting?🧑‍💻

Linux Shell Scripting is a way of automating tasks and executing commands in the Linux operating system using scripts written in the shell language. 🐧💻🚀

Example: Let's say you want to create a script to automate the process of backing up your important files. You can create a shell script that copies the files to a backup directory:

#!/bin/bash

# This is a simple backup script
backup_dir="/home/user/backup"
source_dir="/home/user/documents"

cp -r $source_dir $backup_dir

In this example, the script copies all files from the "documents" directory to the "backup" directory. Running the script automates the backup process and saves you time! ⏳💾

Linux Shell Scripting makes complex tasks simpler, enhances productivity, and empowers DevOps engineers to streamline workflows efficiently. Happy scripting! 🤖✨

🧺🗑️What is #!/bin/bash? can we write #!/bin/sh as well?

📝 #!/bin/bash is called a shebang or hashbang in Linux. It's a special line at the beginning of a shell script that tells the system which interpreter to use to run the script. In this case, it specifies that the script should be executed using the Bash shell.

🤔 Yes, you can also use #!/bin/sh as the shebang line. This tells the system to use the default system shell to run the script, which is often Bash but can be another shell like Dash or Bourne shell (sh).

Example: Let's say you have a shell script named "myscript.sh". If you use #!/bin/bash as the shebang, the script will be executed with the Bash shell, like this:

#!/bin/bash
echo "Hello, World!"

If you use #!/bin/sh as the shebang, the script will be executed with the default system shell, which might be Bash or another compatible shell:

#!/bin/sh
echo "Hello, World!"

Both shebangs will produce the same output: "Hello, World!".

🥅🧑‍💻Write a Shell Script which prints❓ I will complete #90DaysOofDevOps challenge.

Simple shell script that prints the statement "I will complete #90DaysOfDevOps challenge".

#!/bin/bash

# Shell Script for 90DaysOfDevOps Challenge
echo "I will complete #90DaysOfDevOps challenge! 🚀💪"

Save the script with a ".sh" extension, for example, "challenge_script.sh". Then, make it executable using the command: chmod +x challenge_script.sh

Run the script by typing: ./challenge_script.sh

The output will be:

I will complete #90DaysOfDevOps challenge! 🚀💪

The above script uses the echo command to print the specified statement! 🌟🐧💻.

🕸️✨Write a Shell Script to take user input👤, input from arguments and print🖨️ the variables.💥🗨️🗨️

🐚💬 Shell Scripting Fun: Print Variables! 🚀🎉

It is a simple code to take user input and input from command-line arguments, then print the variables with a touch of magic! ✨💡.

Open any text editor e.g.:- Vi, Vim etc.

In my case, I am using Vi editor. open the editor by typing Vi "File name".

Just type the below script in the file and save it by pressing ESC and then wq.

Here:- W is for save, q for quit.

#!/bin/bash

# Taking user input
read -p "Enter your name: " name
echo "Hello, $name! 👋"

# Input from command-line arguments
echo "You provided $# arguments. Here they are:"

# Loop through command-line arguments and print them
for arg in "$@"
do
    echo "Argument: $arg 🚀"
done

Save the above code in a file, let's say "variable.sh". To run the script,You have to give executable permission to the respective file as you have given in previous file and after that open the terminal, navigate to the script's directory, and execute the following command:

Output🖨️:

😀😃Here, 1 2 3 4 are the arguments🌈🔥.

🧭⌨️Write an Example of If else in Shell Scripting by comparing 2️⃣numbers.

Below is the script where we are using if else in Shell Scripting to compare two numbers:

#!/bin/bash

# Variables
number1=10
number2=20

# If-Else Statement
if [ $number1 -gt $number2 ]; then
    echo "Number 1 is greater than Number 2! 🚀"
elif [ $number1 -lt $number2 ]; then
    echo "Number 2 is greater than Number 1! 🌟"
else
    echo "Both numbers are equal! ✨"
fi

In this above script example, we have two variables, number1 and number2, with values 10 and 20, respectively. The script compares the two numbers using the if-else statement. If number1 is greater than number2, it prints "Number 1 is greater than Number 2! 🚀". If number1 is less than number2, it prints "Number 2 is greater than Number 1! 🌟". If both numbers are equal, it prints "Both numbers are equal! ✨".

You can modify the values of number1 and number2 to experiment with different comparisons! 🧪😊

Thank you all for joining me on this exciting DevOps journey! 🙏🚀

I hope you found value in the blog and gained valuable insights into the world of DevOps. Remember, the key to success lies in continuous learning and collaboration. Let's keep pushing boundaries and elevating our skills as DevOps engineers. Feel free to reach out if you have any questions or need further assistance🚀 by following me on Hashnode, LinkedIn (linkedin.com/in/mahesh-verma-441178250), and GitHub (https://github.com/maheshverma123)..

Happy DevOps adventures ahead! 🌟😊 #DevOpsEngineer #ContinuousLearning #TechEnthusiast