Environment variables vs local variables in Bash Scripting - Hands-On Comparison

Environment variables vs local variables in Bash scripting

📖 Scenario: You are writing a simple Bash script to understand how environment variables and local variables work differently. This is important when you want to control which variables are visible to other programs or scripts.

🎯 Goal: Learn how to create local variables and environment variables in Bash, and see how they behave differently when running a child script.

📋 What You'll Learn

Create a local variable in a Bash script

Create an environment variable in a Bash script

Write a child script that prints both variables

Observe which variables are accessible in the child script

💡 Why This Matters

🌍 Real World

Understanding environment vs local variables helps when writing scripts that call other scripts or programs, ensuring the right data is shared or kept private.

💼 Career

Many automation and deployment tasks require managing environment variables correctly to configure software and services.

1

Create a Bash script with a local variable

Create a Bash script called parent.sh and inside it, create a local variable called local_var with the value local_value.

Bash Scripting

# Create a local variable called local_var with value local_value
# Your code here

Need a hint?

Use the syntax variable_name="value" to create a local variable in Bash.

2

Add an environment variable to the script

In parent.sh, add an environment variable called env_var with the value env_value by exporting it.

Bash Scripting

local_var="local_value"
# Export an environment variable called env_var with value env_value
# Your code here

Need a hint?

Use export variable_name="value" to create an environment variable in Bash.

3

Create a child script to print both variables

Create a new Bash script called child.sh that prints the values of local_var and env_var using echo.

Bash Scripting

local_var="local_value"
export env_var="env_value"

# Create child.sh script below
# Your code here

Need a hint?

Use echo "variable_name=$variable_name" to print variable values in Bash.

4

Run child script from parent and observe output

In parent.sh, add a line to run child.sh after setting the variables. Then run bash parent.sh in the terminal and observe the output.

Bash Scripting

local_var="local_value"
export env_var="env_value"

# child.sh script
#!/bin/bash
echo "local_var=$local_var"
echo "env_var=$env_var"

# Run child.sh from parent.sh
# Your code here

Need a hint?

Use bash ./child.sh to run the child script from the parent script.

Notice that local_var is empty in the child script output because it is local, but env_var is visible because it is exported.