useradd and userdel in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of the useradd command with -m option?

You run the command sudo useradd -m alice on a Linux system. What does the -m option do?

A Locks the user alice account without deleting it.

B Creates a new user named alice but does not create a home directory.

C Deletes the user alice and removes the home directory.

D Creates a new user named alice and also creates a home directory for alice.

💡 Hint

Think about what a home directory means for a user.

The -m option tells useradd to create the user's home directory if it does not exist. Without it, the user is created but no home directory is made.

💻 Command Output

intermediate

What happens when you run userdel without -r?

You run sudo userdel bob on a Linux system. What happens to bob's home directory?

A The command fails because -r is required to delete a user.

B The user bob is deleted but the home directory remains on the system.

C The user bob is locked but not deleted.

D The user bob and the home directory are both deleted.

💡 Hint

Think about what the -r option does in userdel.

Without the -r option, userdel removes the user account but leaves the home directory and files intact.

🔧 Debug

advanced

Why does this useradd command fail?

You run sudo useradd -d /custom/home charlie but get an error. What is the likely cause?

Linux CLI

sudo useradd -d /custom/home charlie

A The -d option is invalid and causes a syntax error.

B The username charlie is already taken.

C The home directory /custom/home does not exist and -m was not used to create it.

D You need to use -r to create a home directory.

💡 Hint

Check if the home directory exists or if you need to create it.

The -d option sets a custom home directory path but does not create it unless combined with -m. If the directory does not exist, useradd fails.

💻 Command Output

advanced

What is the effect of userdel with -r option?

You run sudo userdel -r diana. What happens?

A Deletes the user diana and removes her home directory and mail spool.

B Deletes the user diana but leaves the home directory intact.

C Locks the user diana account without deleting it.

D Deletes only the home directory but keeps the user account.

💡 Hint

The -r option means remove files related to the user.

The -r option removes the user account and deletes the home directory and mail spool files.

🚀 Application

expert

Script to add multiple users with home directories

You want to create a script that adds users named user1, user2, and user3, each with their own home directory. Which script snippet correctly does this?

Linux CLI

#!/bin/bash
for username in user1 user2 user3; do
  # Add user with home directory
  
  
  

done

A sudo useradd -m "$username"

B sudo useradd "$username" -m

C sudo useradd --home "$username" -m

D sudo useradd -d /home/$username

💡 Hint

Remember the correct order and syntax of options for useradd.

The correct syntax is useradd -m username. Option A uses this syntax correctly inside the loop.

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