Subshells (command grouping) in Bash Scripting - Mini Project: Build & Apply

Using Subshells for Command Grouping in Bash

📖 Scenario: You are organizing a simple bash script to manage files in a folder. You want to group commands together so they run in a subshell, keeping your main shell environment clean.

🎯 Goal: Build a bash script that creates a directory, changes into it, creates a file, and lists the contents, all inside a subshell.

📋 What You'll Learn

Create a variable called folder with the value test_dir

Create a subshell that runs these commands: mkdir $folder, cd $folder, touch file.txt, and ls

Print the current directory outside the subshell to show it did not change

💡 Why This Matters

🌍 Real World

Grouping commands in subshells helps keep your main shell environment clean and avoids side effects like changing directories permanently.

💼 Career

Many automation scripts use subshells to run grouped commands safely without affecting the main script environment, which is important for reliable system administration and deployment tasks.

1

Create the folder variable

Create a variable called folder and set it to the string test_dir.

Bash Scripting

# Create a variable called folder and set it to 'test_dir'
# Your code here

Need a hint?

Use folder="test_dir" to create the variable.

2

Write a subshell to create and enter the folder

Write a subshell using parentheses ( ) that runs these commands in order: mkdir $folder, cd $folder, touch file.txt, and ls.

Bash Scripting

folder="test_dir"
# Write a subshell with mkdir, cd, touch, and ls commands
# Your code here

Need a hint?

Use parentheses to group commands: (mkdir "$folder" && cd "$folder" && touch file.txt && ls).

3

Print the current directory outside the subshell

Add a command to print the current directory using pwd outside the subshell to show it did not change.

Bash Scripting

folder="test_dir"
(mkdir "$folder" && cd "$folder" && touch file.txt && ls)
# Print current directory outside subshell
# Your code here

Need a hint?

Simply add pwd after the subshell to print the current directory.

4

Run the script and observe output

Run the script and observe the output. The subshell should list file.txt, and the pwd command should show your original directory.

Bash Scripting

folder="test_dir"
(mkdir "$folder" && cd "$folder" && touch file.txt && ls)
pwd
# Run the script to see output

Need a hint?

The output should show file.txt from the subshell ls command, then your current directory path from pwd.