String comparisons (=, !=, -z, -n) in Bash Scripting - Mini Project: Build & Apply

String comparisons (=, !=, -z, -n) in Bash scripting

📖 Scenario: You are writing a small script to check user input strings for different conditions. This is common when you want to make decisions based on text values in scripts.

🎯 Goal: Build a bash script that creates a string variable, sets a condition string, compares them using = and !=, and checks if strings are empty or not using -z and -n.

📋 What You'll Learn

Create a string variable called input with the exact value hello

Create a string variable called check with the exact value hello

Use an if statement to compare if input equals check using =

Use an if statement to compare if input does not equal world using !=

Use -z to check if a variable empty_str is empty

Use -n to check if a variable non_empty_str is not empty

Print messages for each condition to show the result

💡 Why This Matters

🌍 Real World

Scripts often need to check text values to decide what to do next, like checking if a filename is empty or if a user typed a specific command.

💼 Career

Understanding string comparisons in bash is essential for writing automation scripts, deployment scripts, and system maintenance tasks in many IT and DevOps roles.

1

Create the initial string variables

Create a string variable called input and set it to hello. Also create a string variable called check and set it to hello.

Bash Scripting

# Create the string variables 'input' and 'check'
# Your code here

Need a hint?

Use variable="value" syntax to create string variables in bash.

2

Add variables to test empty and non-empty strings

Create a string variable called empty_str and set it to an empty string "". Create another string variable called non_empty_str and set it to bash.

Bash Scripting

input="hello"
check="hello"
# Create 'empty_str' as empty string and 'non_empty_str' as "bash"
# Your code here

Need a hint?

Set empty_str to "" and non_empty_str to "bash" using the same syntax as before.

3

Write string comparison conditions using = and !=

Write an if statement that checks if input equals check using =. Inside it, print "Strings are equal". Then write another if statement that checks if input does not equal world using !=. Inside it, print "Strings are not equal".

Bash Scripting

input="hello"
check="hello"
empty_str=""
non_empty_str="bash"
# Write if statement to check if input = check and print message
# Write if statement to check if input != "world" and print message
# Your code here

Need a hint?

Use if [ "$var1" = "$var2" ] and if [ "$var1" != "value" ] syntax for string comparisons in bash.

4

Check if strings are empty or not using -z and -n and print results

Write an if statement that uses -z to check if empty_str is empty. If true, print "empty_str is empty". Then write an if statement that uses -n to check if non_empty_str is not empty. If true, print "non_empty_str is not empty".

Bash Scripting

input="hello"
check="hello"
empty_str=""
non_empty_str="bash"

if [ "$input" = "$check" ]; then
    echo "Strings are equal"
fi

if [ "$input" != "world" ]; then
    echo "Strings are not equal"
fi

# Use -z to check if empty_str is empty and print message
# Use -n to check if non_empty_str is not empty and print message
# Your code here

Need a hint?

Use if [ -z "$var" ] to check empty and if [ -n "$var" ] to check not empty.