Why user management secures systems in Linux CLI - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the command to list all users on a Linux system.

Linux CLI

cat /etc/[1]

Drag options to blanks, or click blank then click option'

Ahosts

Bpasswd

Cshadow

Dgroup

Attempts:

3 left

💡 Hint

Common Mistakes

Using /etc/hosts instead of /etc/passwd

Using /etc/shadow which is for passwords only

The /etc/passwd file contains user account information, so listing it shows all users.

2fill in blank

medium

Complete the command to add a new user named 'alice'.

Linux CLI

sudo [1] alice

Drag options to blanks, or click blank then click option'

Auserdel

Bpasswd

Cgroupadd

Duseradd

Attempts:

3 left

💡 Hint

Common Mistakes

Using userdel which deletes users

Using passwd which changes passwords

The useradd command creates a new user account.

3fill in blank

hard

Fix the error in the command to change user 'bob' password.

Linux CLI

sudo [1] bob

Drag options to blanks, or click blank then click option'

Apasswd

Buseradd

Cusermod

Dgroupmod

Attempts:

3 left

💡 Hint

Common Mistakes

Using useradd which adds users

Using usermod which modifies user properties but not passwords

The passwd command is used to change a user's password.

4fill in blank

hard

Fill both blanks to create a user 'charlie' with a home directory and default shell /bin/bash.

Linux CLI

sudo [1] -m -s [2] charlie

Drag options to blanks, or click blank then click option'

Auseradd

B/bin/sh

C/bin/bash

Dusermod

Attempts:

3 left

💡 Hint

Common Mistakes

Using usermod instead of useradd

Setting shell to /bin/sh instead of /bin/bash

useradd creates the user, -m makes a home directory, and -s /bin/bash sets the shell.

5fill in blank

hard

Fill all three blanks to list all users with UID greater than 1000 from /etc/passwd.

Linux CLI

awk -F: '{{ if ($3 [1] [2]) print $1 }}' /etc/[3]

Drag options to blanks, or click blank then click option'

A<

B1000

Cpasswd

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>'

Using /etc/shadow instead of /etc/passwd

This command uses awk to print usernames where UID (field 3) is greater than 1000 from /etc/passwd.

Practice

1. Why is user management important for system security?

easy

A. It updates software without user permission

B. It controls who can access the system and what they can do

C. It cleans temporary files automatically

D. It speeds up the computer's processing power

Solution

1. Step 1: Understand user management purpose

   User management sets permissions and access rights for users.

2. Step 2: Connect user control to security

   By controlling access, it prevents unauthorized changes and protects data.

3. Final Answer:

   It controls who can access the system and what they can do -> Option B

4. Quick Check:

   User access control = security [OK]

Hint: User management controls access rights to secure system [OK]

Common Mistakes:

• Confusing user management with system speed
• Thinking it cleans files automatically
• Believing it updates software silently

2. Which command is used to add a new user in Linux?

easy

A. useradd

B. adduserlist

C. createuser

D. newuser

Solution

1. Step 1: Recall Linux user creation commands

   The standard command to add a user is useradd.

2. Step 2: Verify other options

   Other options are not valid Linux commands for adding users.

3. Final Answer:

   useradd -> Option A

4. Quick Check:

   Linux add user = useradd [OK]

Hint: Use 'useradd' to add users in Linux [OK]

Common Mistakes:

• Using non-existent commands like 'newuser'
• Confusing 'adduserlist' with 'useradd'
• Trying 'createuser' which is not standard

3. What will be the output of the command id alice if user 'alice' exists with UID 1001 and belongs to groups 'users' and 'admin'?

medium

A. uid=1001(alice) gid=1001(alice) groups=1001(alice),1002(admin)

B. uid=1001(alice) gid=100(users) groups=100(users),101(admin)

C. uid=1001(alice) gid=1001(alice) groups=1001(alice),1002(users),1003(admin)

D. uid=1001(alice) gid=1001(alice) groups=1001(alice),1002(admin),1003(users)

Solution

1. Step 1: Understand id command output

   The id command shows user ID (uid), group ID (gid), and groups with their IDs.

2. Step 2: Match given user and groups

   User 'alice' has UID 1001 and belongs to groups 'users' and 'admin'. The gid usually matches the user's primary group, here 1001(alice). Groups listed include primary and secondary groups with their IDs.

3. Final Answer:

   uid=1001(alice) gid=1001(alice) groups=1001(alice),1002(users),1003(admin) -> Option C

4. Quick Check:

   id shows uid, gid, groups = uid=1001(alice) gid=1001(alice) groups=1001(alice),1002(users),1003(admin) [OK]

Hint: id command shows user and group IDs clearly [OK]

Common Mistakes:

• Mixing group IDs and names incorrectly
• Assuming gid is 'users' instead of user's primary group
• Adding extra groups not specified

4. You tried to add a user with useradd bob but got an error 'useradd: command not found'. What is the likely cause?

medium

A. The username 'bob' is already taken

B. You typed the command incorrectly; it should be 'adduser bob'

C. The system does not support user accounts

D. You need to run the command as root or with sudo

Solution

1. Step 1: Analyze the error message

   'command not found' means the shell cannot find the useradd command in your path or permission is denied.

2. Step 2: Check permissions and command availability

   Adding users requires root privileges; running without sudo or root causes this error.

3. Final Answer:

   You need to run the command as root or with sudo -> Option D

4. Quick Check:

   Permission needed for useradd = You need to run the command as root or with sudo [OK]

Hint: Use sudo before useradd to avoid permission errors [OK]

Common Mistakes:

• Assuming username conflict causes 'command not found'
• Thinking system lacks user accounts
• Confusing 'useradd' with 'adduser' command

5. You want to secure a system by limiting user access. Which approach best uses user management to achieve this?

hard

A. Create separate user accounts with minimal permissions and use groups to control access

B. Allow all users to share one admin account for convenience

C. Disable user accounts and only use root for all tasks

D. Remove all users except guest to simplify management

Solution

1. Step 1: Understand security best practices

   Limiting user permissions and using groups helps control who can do what on the system.

2. Step 2: Evaluate options for security

   Sharing admin accounts or using root for all tasks is risky. Removing users excessively limits functionality.

3. Final Answer:

   Create separate user accounts with minimal permissions and use groups to control access -> Option A

4. Quick Check:

   Least privilege + groups = secure user management [OK]

Hint: Use minimal permissions and groups to secure users [OK]

Common Mistakes:

• Sharing admin accounts weakens security
• Using root for all tasks is unsafe
• Removing users breaks system usability