useradd and userdel in Linux CLI - Mini Project: Build & Apply

Managing Users with useradd and userdel Commands

📖 Scenario: You are a system administrator managing users on a Linux server. You need to add new users and remove users safely using command-line tools.

🎯 Goal: Learn how to create new users with useradd and delete users with userdel commands through a guided script.

📋 What You'll Learn

Use the useradd command to create users

Use the userdel command to delete users

Use variables to store usernames

Print confirmation messages after each operation

💡 Why This Matters

🌍 Real World

System administrators often need to add and remove users on Linux servers to manage access and security.

💼 Career

Knowing how to use user management commands like useradd and userdel is essential for Linux system administration roles.

1

Create a variable for the new username

Create a variable called new_user and set it to the exact string testuser.

Linux CLI

# Create a variable called new_user and set it to 'testuser'
# Your code here

Hint

Use new_user='testuser' to assign the username.

2

Create a variable for the username to delete

Create a variable called del_user and set it to the exact string olduser.

Linux CLI

new_user='testuser'
# Create a variable called del_user and set it to 'olduser'
# Your code here

Hint

Use del_user='olduser' to assign the username to delete.

3

Add the new user and delete the old user

Use the useradd command with $new_user to add the new user, and use the userdel command with $del_user to delete the old user. Write both commands on separate lines.

Linux CLI

new_user='testuser'
del_user='olduser'
# Add new user with useradd and delete old user with userdel
# Your code here

Hint

Use useradd "$new_user" and userdel "$del_user" commands.

4

Print confirmation messages

Print the exact messages User testuser added successfully. and User olduser deleted successfully. on separate lines using echo commands.

Linux CLI

new_user='testuser'
del_user='olduser'
useradd "$new_user"
userdel "$del_user"
# Print confirmation messages
# Your code here

Hint

Use echo "User testuser added successfully." and echo "User olduser deleted successfully.".

Practice

1. What does the useradd command do in Linux?

easy

A. Lists all users on the system

B. Deletes an existing user account

C. Changes the password of a user

D. Creates a new user account

Solution

1. Step 1: Understand the purpose of useradd

   The useradd command is used to create new user accounts on a Linux system.

2. Step 2: Differentiate from other commands

   userdel deletes users, passwd changes passwords, and listing users is done by other commands like cat /etc/passwd.

3. Final Answer:

   Creates a new user account -> Option D

4. Quick Check:

   useradd = create user [OK]

Hint: Remember: add means create, del means delete [OK]

Common Mistakes:

• Confusing useradd with userdel
• Thinking useradd lists users
• Mixing useradd with password commands

2. Which of the following is the correct syntax to create a user with a home directory?

easy

A. useradd -r username

B. useradd username

C. useradd -m username

D. userdel -m username

Solution

1. Step 1: Identify the option for creating home directory

   The -m option with useradd creates the user's home directory.

2. Step 2: Check other options

   -r is for system users or removing files with userdel, so it is incorrect here.

3. Final Answer:

   useradd -m username -> Option C

4. Quick Check:

   -m means make home directory [OK]

Hint: Use -m with useradd to create home folder [OK]

Common Mistakes:

• Using userdel instead of useradd
• Forgetting the -m option for home directory
• Using -r option with useradd

3. What will be the result of this command sequence?

useradd -m alice
userdel alice

medium

A. User alice is deleted but home directory remains

B. User alice and home directory are deleted

C. User alice is created but deletion fails

D. Syntax error occurs

Solution

1. Step 1: Create user alice with home directory

   useradd -m alice creates user alice and a home folder.

2. Step 2: Delete user alice without -r option

   userdel alice deletes the user but does not remove the home directory unless -r is used.

3. Final Answer:

   User alice is deleted but home directory remains -> Option A

4. Quick Check:

   userdel without -r keeps files [OK]

Hint: userdel needs -r to remove home directory [OK]

Common Mistakes:

• Assuming home directory is deleted without -r
• Thinking userdel fails without -r
• Confusing useradd options with userdel

4. You run userdel -r bob but get an error saying user bob does not exist. What is the likely cause?

medium

A. The home directory is missing

B. User bob was never created

C. You need to use useradd to delete users

D. The -r option is invalid with userdel

Solution

1. Step 1: Understand the error message

   The error says user bob does not exist, so the system cannot delete a non-existent user.

2. Step 2: Check command validity

   userdel -r bob is valid syntax to delete user and home directory, so the error is not due to syntax.

3. Final Answer:

   User bob was never created -> Option B

4. Quick Check:

   User must exist before deletion [OK]

Hint: Check if user exists before deleting [OK]

Common Mistakes:

• Thinking -r is invalid option
• Trying to delete users with useradd
• Assuming home directory missing causes error

5. You want to create a script that adds a user with a home directory and then deletes the user along with all their files. Which commands should you use in order?

hard

A. useradd -m username; userdel -r username

B. useradd username; userdel username

C. userdel -r username; useradd -m username

D. userdel username; useradd username

Solution

1. Step 1: Add user with home directory

   Use useradd -m username to create the user and their home folder.

2. Step 2: Delete user and all files

   Use userdel -r username to remove the user and their home directory and files.

3. Final Answer:

   useradd -m username; userdel -r username -> Option A

4. Quick Check:

   Add with -m, delete with -r for files [OK]

Hint: Add with -m, delete with -r to remove files [OK]

Common Mistakes:

• Deleting before adding user
• Forgetting -m when adding user
• Forgetting -r when deleting user