Quiz Module 5 - Users and Permissions

Instructions

This quiz contains 30 multiple-choice questions to validate your understanding of Module 5.

Tip: Answer each question before revealing the answer. The answers are hidden just after each question.

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Question 1

What is the UID (User ID) of the root user?

1. 0

2. 1

3. 1000

4. 999

See explanation

Correct answer: 0

Explanation: The root user always has UID 0. It is the unique identifier that gives it all privileges on the system.

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Question 2

Which command is used to create a user on Ubuntu 24.04?

1. createuser

2. useradd or adduser

3. newuser

4. mkuser

See explanation

Correct answer: useradd or adduser

Explanation: useradd is the basic command to create a user. adduser (Ubuntu/Debian) is a more user-friendly interface that asks interactive questions. Example: sudo useradd -m -s /bin/bash username.

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Question 3

Which file contains user information?

1. /etc/users

2. /etc/passwd

3. /etc/shadow

4. /home/passwd

See explanation

Correct answer: /etc/passwd

Explanation: /etc/passwd contains basic user information: name, UID, GID, home directory, shell. Format: username:x:UID:GID:comment:home:shell. Encrypted passwords are in /etc/shadow.

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Question 4

Which file contains encrypted user passwords?

1. /etc/passwd

2. /etc/shadow

3. /etc/password

4. /home/shadow

See explanation

Correct answer: /etc/shadow

Explanation: /etc/shadow contains encrypted passwords and password policies. This file is readable only by root for security reasons.

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Question 5

Which command is used to modify an existing user?

1. moduser

2. usermod

3. edituser

4. changeuser

See explanation

Correct answer: usermod

Explanation: usermod is used to modify an existing user. Examples: sudo usermod -s /bin/zsh username (change shell), sudo usermod -aG sudo username (add to sudo group), sudo usermod -L username (lock account).

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Question 6

Which command is used to delete a user?

1. deluser

2. userdel

3. removeuser

4. rmuser

See explanation

Correct answer: userdel

Explanation: userdel deletes a user. Options: sudo userdel username (keeps home), sudo userdel -r username (also deletes home directory). Option -f to force if active processes.

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Question 7

Which command is used to create a group?

1. creategroup

2. groupadd

3. newgroup

4. mkgroup

See explanation

Correct answer: groupadd

Explanation: groupadd creates a new group. Examples: sudo groupadd developers, sudo groupadd -g 2000 developers (with specific GID).

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Question 8

Which file contains group information?

1. /etc/groups

2. /etc/group

3. /etc/passwd

4. /home/group

See explanation

Correct answer: /etc/group

Explanation: /etc/group contains group information: name, GID, members. Format: groupname:x:GID:members. Example: developers:x:1001:user1,user2,user3.

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Question 9

Which command is used to add a user to a group?

1. addtogroup

2. usermod -aG

3. groupadd -u

4. adduser -g

See explanation

Correct answer: usermod -aG

Explanation: sudo usermod -aG groupname username adds a user to a secondary group. The -a (append) option is important to not replace other groups. The user must log out/in for changes to take effect.

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Question 10

Which command is used to view a user's groups?

1. showgroups

2. groups or id

3. listgroups

4. usergroups

See explanation

Correct answer: groups or id

Explanation: groups displays the current user's groups. groups username shows a specific user's groups. id displays UID, GID, and all groups with more details.

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Question 11

Which command is used to change a file's owner?

1. chuser

2. chown

3. owner

4. setowner

See explanation

Correct answer: chown

Explanation: chown (change owner) modifies a file's owner and/or group. Examples: sudo chown user:group file, sudo chown user file, sudo chown -R user:group /directory (recursive).

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Question 12

Which command is used to modify a file's permissions?

1. chperm

2. chmod

3. perm

4. setperm

See explanation

Correct answer: chmod

Explanation: chmod (change mode) modifies permissions. Syntaxes: chmod 755 file (octal), chmod u+x file (symbolic). Examples: chmod +x script.sh, chmod 644 file.txt, chmod -R 755 /directory (recursive).

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Question 13

What are the three basic permissions for Linux files?

1. Read (r), Write (w), Execute (x)

2. Create, Read, Delete

3. Public, Private, Protected

4. User, Group, Other

See explanation

Correct answer: Read (r), Write (w), Execute (x)

Explanation: The basic Linux permissions are: read, write, execute. These permissions apply to the owner, group, and others.

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Question 14

What is the octal value for the permissions rwxr-xr-x?

1. 644

2. 755

3. 777

4. 555

See explanation

Correct answer: 755

Explanation: rwxr-xr-x = 111 101 101 in binary = 7 5 5 in octal. The owner has all permissions (7), the group and others have read and execute (5). This is the typical permission for executables.

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Question 15

Which command is used to run a command with root privileges?

1. su

2. sudo

3. root

4. admin

See explanation

Correct answer: sudo

Explanation: sudo (superuser do) allows running a command with root privileges. Examples: sudo apt update, sudo systemctl restart service. Configuration is in /etc/sudoers.

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Question 16

Which file configures sudo?

1. /etc/sudo

2. /etc/sudoers

3. /etc/sudo.conf

4. /home/sudoers

See explanation

Correct answer: /etc/sudoers

Explanation: /etc/sudoers configures sudo permissions. Edit it with sudo visudo (checks syntax). Never edit directly with a normal editor to avoid syntax errors that could block sudo access.

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Question 17

What is the SUID (Set User ID) bit?

1. A file type

2. A permission bit that allows a file to run with the owner's privileges

3. A system user

4. A special group

See explanation

Correct answer: A permission bit that allows a file to run with the owner's privileges

Explanation: The SUID bit (s) allows an executable to run with the owner's privileges, even if launched by another user. Example: passwd has SUID to allow users to change their password. Set with chmod u+s file or chmod 4755 file.

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Question 18

What is the SGID (Set Group ID) bit?

1. A file type

2. A permission bit that allows a file to run with group privileges, or forces new files in a directory to belong to the group

3. A system user

4. A special group

See explanation

Correct answer: A permission bit that allows a file to run with group privileges, or forces new files in a directory to belong to the group

Explanation: The SGID bit (s) on an executable allows it to run with group privileges. On a directory, it forces new files created to belong to the directory's group. Set with chmod g+s file or chmod 2755 file.

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Question 19

What is the sticky bit?

1. A file type

2. A permission bit that prevents users from deleting other users' files in a directory

3. A system user

4. A special group

See explanation

Correct answer: A permission bit that prevents users from deleting other users' files in a directory

Explanation: The sticky bit (t) on a directory prevents users from deleting or renaming other users' files, even if they have write permissions. Useful for /tmp. Set with chmod +t directory or chmod 1777 directory.

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Question 20

Which command is used to see the current user?

1. user

2. whoami or id

3. currentuser

4. me

See explanation

Correct answer: whoami or id

Explanation: whoami displays the current username. id shows more information: UID, GID, and all groups. id -u shows only the UID, id -g only the GID.

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Question 21

Which command is used to switch users?

1. switch

2. su

3. change

4. login

See explanation

Correct answer: su

Explanation: su username switches users. su - username switches with the full environment (like a new login). su or su - switches to root. To exit, use exit.

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Question 22

What is the octal value for the permissions rw-r--r--?

1. 644

2. 755

3. 777

4. 600

See explanation

Correct answer: 644

Explanation: rw-r--r-- = 110 100 100 in binary = 6 4 4 in octal. The owner has read and write (6), the group and others have only read (4). This is the typical permission for text files.

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Question 23

What is an ACL (Access Control List)?

1. A file type

2. An advanced permission system that allows granular permissions by user and group

3. A system user

4. A special group

See explanation

Correct answer: An advanced permission system that allows granular permissions by user and group

Explanation: ACLs allow defining specific permissions for individual users or groups beyond standard permissions (owner/group/others). Commands: setfacl (set), getfacl (view). Example: setfacl -m u:user1:rw file.

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Question 24

Which command is used to view a file's ACLs?

1. showacl

2. getfacl

3. viewacl

4. acl

See explanation

Correct answer: getfacl

Explanation: getfacl file displays a file or directory's ACLs. setfacl is used to set ACLs. Examples: setfacl -m u:user1:rw file (add permission), setfacl -x u:user1 file (remove ACL).

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Question 25

Which command is used to lock a user account?

1. lockuser

2. usermod -L

3. userlock

4. lock

See explanation

Correct answer: usermod -L

Explanation: sudo usermod -L username locks a user account (adds a ! in front of the password hash in /etc/shadow). sudo usermod -U username unlocks. sudo passwd -l username does the same.

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Question 26

What is the difference between the primary group and secondary groups?

1. No difference

2. A user has only one primary group but can belong to multiple secondary groups

3. The primary group is optional

4. Secondary groups are more important

See explanation

Correct answer: A user has only one primary group but can belong to multiple secondary groups

Explanation: The primary group is defined in /etc/passwd and is used by default for new files. Secondary groups are in /etc/group and provide additional permissions.

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Question 27

Which command is used to change a user's password?

1. changepass

2. passwd

3. setpass

4. modpass

See explanation

Correct answer: passwd

Explanation: passwd changes the current user's password. sudo passwd username allows root to change another user's password. sudo passwd -l username locks an account.

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Question 28

What is the octal value for the permissions rwxrwxrwx?

1. 644

2. 755

3. 777

4. 666

See explanation

Correct answer: 777

Explanation: rwxrwxrwx = 111 111 111 in binary = 7 7 7 in octal. Everyone (owner, group, others) has all permissions. This is generally too permissive and not recommended for security reasons.

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Question 29

Which command is used to see connected users?

1. users

2. who or w

3. connected

4. listusers

See explanation

Correct answer: who or w

Explanation: who displays connected users with their terminals and login times. w shows more information: users, terminals, connection times, system load, and current commands. users just lists the names.

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Question 30

Which command is used to delete a group?

1. delgroup

2. groupdel

3. removegroup

4. rmgroup

See explanation

Correct answer: groupdel

Explanation: sudo groupdel groupname deletes a group. The group cannot be deleted if it is the primary group of a user. You must first change the user's primary group or delete the user.

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Quiz Result

Congratulations on completing the Module 5 quiz!

Score:

• 25-30 correct answers: Excellent! You master Linux user and permission management.
• 20-24 correct answers: Very good! Review the concepts where you had difficulties.
• 15-19 correct answers: Good! Review the chapters on users and permissions.
• Less than 15: Recommended to review the module before continuing.

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Next Steps

Now that you have validated your knowledge:

Module 6: Shell Scripting
Practical Labs: Practice user and permission management with Module 5 labs

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Quiz created on: December 2024 - Tested on Ubuntu 24.04