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Learn Bash Scripting With Me 🚀 - Day 2

Day 2 – Variables

In case you’d like to revisit or catch up on what we covered on Day One, here’s the link:

https://dev.to/babsarena/learn-bash-scripting-with-me-day-1-1ekd
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Variables in Bash scripting are used to store data, such as numbers, text, or file paths. They are a way to label and reference information that can be used later in a script.

  • We begin by creating a file using any text editor of our choice and naming it variables.sh.

Declaring the Shell

At the very top of the script, specify the shell you want to use:

#!/bin/bash
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Creating a Variable

Let’s create a variable called NAME.

👉 Best Practice:

  • Variable names in Bash are usually written in capital (block) letters.

  • Using lowercase will still work, but uppercase is the recommended convention.

Important Rules When Declaring Variables

  • No spaces before or after the = sign, otherwise the script will fail.

NAME = "Babs" ❌ Invalid
NAME="Babs" ✅ Valid

NB - Strings must be inside quotes (" ").

NB - Numbers don’t need quotes.

AGE=25 ✅ Valid
CITY="Nairobi" ✅ Valid

Using Variables

To call a variable, use the dollar sign ($):

echo "My name is $NAME"
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NB - You can also use curly braces {} when combining variables with text:

SPORT="Foot"
echo "The most popular sport is ${SPORT}ball"
Output: The most popular sport is Football

Pictorial Examples of the script and the outcome

  • Script 1

  • Script 1 Outcome:

  • Script 2

  • Script 2 Outcome:

Naming Rules

  • Variable names must start with an alphabet (A–Z or a–z).

  • They cannot start with a number.

01_NAME="Test" # ❌ Invalid
NAME_01="Test" # ✅ Valid
SPORT_07="Test" # ✅ Valid

NB - If variables are not properly declared, the script will return an error.

🔎 Things to Keep in Mind

  • If your script fails to run, ensure that the file is executable.

You can check this with:

ls -la
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  • If it’s not executable, make it executable with: 
chmod +x variables.sh
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  • Always enclose string variables in quotation marks (" ").

  • Missing quotes may cause your script to fail.

✨ And that’s the foundation of working with variables in Bash scripting for day 2!

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