Day 3: Mastering Bash Scripting - Basic and Essential Concepts

Adrian Rubico

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Aug 7, 2024

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01:07 AM GMT+8

The Linux environment has been a big part of my life for a long time. As a DevOps engineer, I would like to share my knowledge with a bash scripting approach that can be significantly achieved, such as automating processes, managing system configurations, or optimizing workflow. In this first part of our series, we will cover the essential concepts you need to get started with Bash scripting.

Understanding the Role of the Linux Kernel

Before we get started we must know the fundamentals of the Linux environment. So what is Linux kernel, the Linux kernel is like a brain of the operating system that can manage how the computer interacts with its hardware. With this, it manages system resources, handles memory, and facilitates communication between the hardware and the software.

By using system calls, you often communicate directly with the kernel when running Bash scripts. You can use your script to read or write files by translating commands into kernel instructions. As a result of interacting with the kernel, Bash scripting provides flexibility and power to automate various tasks on your computer.

What is a Shell?

Operating systems provide users with command-line interfaces called shells. The user and the kernel act as a bridge that enables to execute commands, run programs, and perform various tasks.

There are different types of shells available:

  • Bourne Shell (sh)
  • Bourne-Again Shell (bash)
  • C Shell (csh)
  • Korn Shell (ksh)
  • Z Shell (zsh)

This discussion will focus on bash scripting. As the most widely used shell on Unix-like systems, including Linux and macOS, bash is a crucial tool for many users.

Writing Your First Script

Let’s begin by writing a simple script. Open your favorite text editor (nano,vim or vi) and create a new file with a .sh extension, for example, first_script.sh

bash 
#!bin/bash
# This is comment
echo "#90DaysDevOpsChallenge"

💡 Remember to change the permissions using the chmod +x first_script.sh command after creating a script. 

Let's break down the script:

  • #!/bin/bash: is commonly known shebang, and it tells the system which interpreter to use to run the script. In this case, we are using Bash.
  • # this is a comment: Comments starts with # in Bash and ignored by the interpreter.
  • echo "#90DaysDevOpsChallenge": This command prints the text "#90DaysDevOpsChallenge" to the terminal.

Next, let's level up a bit by modifying the script as shown in the example below.

bash 
#!/bin/bash
# This is comment
echo "#90DaysDevOpsChallenge"
echo

echo "The uptime of the system is:"
uptime
echo

echo "Memory Utilization"
free -h
echo

echo "Disk Utilization"
df -h

When we write a script, it allows the interpreter to call system functions. In this example, the uptime command tells how long the system has been running, the df -h command provides the disk usage of the system, and free -h shows the memory usage of the system. By combining these commands into a script, we can execute them in a single run.

The Importance of Bash Scripting in DevOps

One of the fundamental tools in the DevOps toolkit is Bash scripting within Linux or Unix-based environment. Approaching the scripting in the DevOps makes invaluable skill for efficiently managing and automating processes.

The following key highlights of this bash scripting in Devops:

  • Automates repetitive task, reducing manual efforts and errors.
  • Integrates with CI/CD pipelines.
  • Interactivity with different tools like Docker, Kubernetes, and cloud platforms.
  • Facilitates quick troubleshooting and debugging.
  • Offers a low learning curve with extensive community support.

Final Thoughts

Mastering the fundamentals of Bash scripting is your initial step towards unleashing the full potential of automation in a Linux environment. By understanding the Linux kernel and the shell, Bash scripting is a crucial tool in the DevOps toolkit that allows us to automate, streamline, and scale operations effortlessly.

In the next part of our series, we will learn about more advanced topics such as variables, conditions, and loops and how to use these concepts to create more powerful and flexible scripts. Stay tuned as we continue to build Bash scripting expertise, one step at a time.

TAGS:

#90DaysDevOpsChallenge linux scripting

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