passwd (change password) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of passwd command with expired password

What is the output when running passwd -e username on a Linux system?

Linux CLI

passwd -e username

A Error: User 'username' does not exist.

B Password expiry information changed.

C Usage: passwd [options] [username]

D Password successfully changed.

💡 Hint

The -e option forces password expiration for the user.

The passwd -e username command expires the user's password immediately, so the user must change it at next login. The output confirms this action.

💻 Command Output

intermediate

Result of passwd command with invalid option

What error message appears when running passwd -z on a Linux system?

Linux CLI

passwd -z

A

passwd: invalid option -- 'z'
Try 'passwd --help' for more information.

B passwd: option requires an argument -- 'z'

C Password successfully updated.

D passwd: unknown command 'z'

💡 Hint

Check how passwd handles unknown options.

The passwd command shows an error for invalid options, indicating the invalid option and suggesting help.

🔧 Debug

advanced

Why does passwd fail with 'Authentication token manipulation error'?

You run passwd to change a user's password but get the error: Authentication token manipulation error. What is the most likely cause?

A The system is out of disk space on the root partition.

B The /etc/passwd file is missing from the system.

C The user is not in the sudoers file and lacks permission to change the password.

D The password entered does not meet complexity requirements.

💡 Hint

Consider permissions needed to update password files.

This error usually happens when the user lacks permission to update password files, often because they are not root or do not have sudo rights.

🚀 Application

advanced

Automate password expiration for multiple users

You want to expire passwords for users alice, bob, and carol using a single shell command. Which command correctly does this?

A passwd -e $(alice bob carol)

B passwd -e alice bob carol

C passwd -e alice && passwd -e bob && passwd -e carol

D for user in alice bob carol; do passwd -e $user; done

💡 Hint

Think about how to run a command multiple times in a loop.

Option D uses a loop to run passwd -e for each user individually, which is the correct approach.

🧠 Conceptual

expert

Understanding passwd password aging options

Which passwd option sets the minimum number of days before a user can change their password again?

A -n

B -w

C -x

D -i

💡 Hint

Minimum days means how soon after a change the password can be changed again.

The -n option sets the minimum number of days between password changes.