If you've ever worked on a Linux machine—whether for development, deployment, or infrastructure—you've come across the terminal. And chances are, you've typed a few commands, maybe copied some from Stack Overflow, and moved on. But imagine if you could automate your daily tasks, manage files, schedule backups, or even monitor systems—all with a few lines of code. That's where Bash scripting comes in.
This blog is for you if you're a person looking to move beyond simple commands and tap into the ability of the Linux shell. I'll take you from the ground up through everything to practical applications - no scripting experience required - merely interest and a terminal.
So, What Is Bash Anyway?
Bash stands for Bourne Again SHell, and it's the default shell on most Linux and macOS computers. It's similar to the command-line interpreter that executes the commands you enter, and when you create a script, you're entering a series of those commands to run in combination.
Although zsh and fish are available, Bash is widely used in DevOps, system administration, cloud automation, and CI/CD pipeline scripting. So, reading Bash is essentially learning the command line lingua franca.
Your First Bash Script
Begin with the bare minimum script. Open up a text editor and paste in:
#!/bin/bash is known as a shebang, and it instructs the system to invoke which interpreter. The second line is merely a print statement.
Save it as hello.sh, then run these commands in the terminal:
>> chmod +x hello.sh
>> ./hello.sh
And voilà—you’ve written and executed your first Bash script!
Tip: It is conventional to use .sh as an extension for bash scripting files, but it is not necessary.
Understanding Variables
Variables in Bash are very straightforward. You don't declare types, you just assign values. For instance:
To assign a variable in BASH, we don't put a space between the = symbol. Also, to access the variable, you put a $ before it. Double quotes are used to get the variable interpreted properly, particularly if it contains spaces.
Getting User Input
Let's get things interactive now. You can ask the user for input with the read command:
This is perfect for creating miniature CLI utilities or scripts that need user input.
Coding with Conditions
Conditional logic comes into play in scripting. Imagine you need to see if a file exists or if two numbers are equal—if statements are what you need to do it. An example follows:
Square brackets hold the condition, and you need spaces on either side of the brackets and operators. It's somewhat unorthodox, but you'll become accustomed to it.
Loops – Repeat the Same Work Without Typing It Out
Loops are the lifesaver when you need to go through a list of things or do a task many times. This is how you loop over all numbers ranging from 1 to 5:
And here's a while loop that iterates 5 times:
These designs make batch processing chores very easy.
Functions – Make Code Repeatable
Once your scripts get larger, doing the same thing over and over again gets ugly. That's where functions save the day. Here is how you go about creating and using one:
Functions aid in organizing your scripts, particularly if you're doing something in more than one place.
Arrays – Keeping Your Data in Order
Bash also has arrays. Suppose you're dealing with environments:
To loop through an array:
There are associative arrays, too, which are closer to Python dictionaries, but you need Bash 4 for those.
File Operations and Redirection
Reading from and writing to files is just very common in scripting. Need to write some logs?
>> echo "Deployment started at $(date)" >> deploy.log
This will append the output to deploy.log. Use > to write over and >> to append.
To read a file line by line:
This is typically used for monitoring logs or config processing files.
Debugging and Error Handling
Debugging Bash scripts is annoying if you have no idea where things are failing. These are a few methods to assist you:
•set -x puts you in debug mode—every command is echoed before running.
•set -e causes your script to quit immediately if any command returns a failure.
•Use trap to trap errors.
These little modifications can make your scripts greatly safer and more maintainable.
Some Real-Life Use Cases
Here are a couple of scripts I use regularly:
1. Health Check Script
This can be called before deploying anything significant.
2. Backup Script
This can assist in automating daily backups using cron jobs.
Best Practices I Swear By
Once you've been scripting in Bash for some time, you begin to learn good practices. Here are a couple that assisted me:
• Always quote your variables, Particularly when working with file paths.
• Use functions freely: Divide your script into sensible chunks.
• Validate input: Don't presume the user is competent.
• Comment your code: Your future self will thank you.
• Use logging: Even a minimal echo "$(date): Something happened" is helpful.
What's Next?
If you've been reading along up to this point, you've already progressed from zero to at least intermediate. Then, experiment with mixing Bash with utilities like curl for APIs, or jq to process JSON. You can even use Bash within your CI/CD pipelines to automate builds and deployments.
Final Thoughts
Bash isn't only a scripting language—it's productivity on steroids. It allows you to talk to your system directly, automate the mundane tasks, and build tools that make your workflow easier. The more you script, the more skilled you'll be.
So, go ahead and open your terminal and begin scripting. You'll be amazed how soon you'll be going from typing ls to making your own CLI tools.