Why regex enables pattern matching in Bash Scripting - See It in Action

Why regex enables pattern matching

📖 Scenario: Imagine you have a list of filenames and you want to find only those that follow a certain pattern, like all files ending with .txt. Using regular expressions (regex) helps you match these patterns easily.

🎯 Goal: Build a simple bash script that uses regex to find filenames ending with .txt from a list.

📋 What You'll Learn

Create a list of filenames in a bash array called files

Create a regex pattern variable called pattern to match filenames ending with .txt

Use a for loop to check each filename against the regex pattern

Print only the filenames that match the regex pattern

💡 Why This Matters

🌍 Real World

Finding files or text that match specific patterns is common in system administration, data processing, and automation tasks.

💼 Career

Understanding regex and pattern matching in scripts helps automate file management and data filtering, valuable skills for DevOps, sysadmins, and automation engineers.

1

Create a list of filenames

Create a bash array called files with these exact filenames: report.txt, image.png, notes.txt, data.csv, summary.txt

Bash Scripting

# Create the bash array called files with the given filenames
# Your code here

Need a hint?

Use parentheses () to create a bash array and double quotes for each filename.

2

Create a regex pattern variable

Create a variable called pattern and set it to the regex string \.txt$ to match filenames ending with .txt

Bash Scripting

files=("report.txt" "image.png" "notes.txt" "data.csv" "summary.txt")
# Create the regex pattern variable called pattern
# Your code here

Need a hint?

Remember to escape the dot . in regex with a backslash \ and use single quotes to avoid shell expansion.

3

Use a for loop to check filenames against the regex

Use a for loop with variable file to iterate over files. Inside the loop, use [[ $file =~ $pattern ]] to check if file matches the regex pattern.

Bash Scripting

files=("report.txt" "image.png" "notes.txt" "data.csv" "summary.txt")
pattern='\.txt$'
# Use a for loop to check each file against the regex pattern
# Your code here

Need a hint?

Use [[ $file =~ $pattern ]] inside the loop to test the regex match.

4

Print the matching filenames

Print the filenames that match the regex pattern inside the if condition using echo "$file".

Bash Scripting

files=("report.txt" "image.png" "notes.txt" "data.csv" "summary.txt")
pattern='\.txt$'
for file in "${files[@]}"; do
    if [[ $file =~ $pattern ]]; then
        # Print the matching filename
        # Your code here
    fi
done

Need a hint?

Use echo "$file" to print the filename inside the if block.