Linux Users & Sudo Permissions – Full Quiz

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This quiz contains 20 questions focused on Linux user management and sudo permissions. It helps DevOps engineers understand access control on production systems.

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Which command is used to switch to the root user?

sudo

sudo su

su root

login

sudo su allows an authorized user to escalate privileges and switch to the root shell.

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Which command switches to another user without loading their environment?

su username

su - username

sudo username

login username

su username switches to the specified user but retains the environment variables of the original user.

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Which command switches to another user and loads their environment?

su username

su - username

sudo username

login username

su - username creates a new login shell, loading the target user's environment variables and home directory.

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Which file stores user account information?

/etc/passwd

/etc/shadow

/etc/group

/etc/sudoers

The /etc/passwd file contains essential user account information, such as username, UID, GID, home directory, and shell.

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Which file stores encrypted user passwords?

/etc/passwd

/etc/shadow

/etc/group

/etc/profile

The /etc/shadow file stores secure, encrypted password information and account expiration details.

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Which command is used to create a new user?

useradd

addgroup

newuser

createuser

useradd is the low-level utility for creating a new user account on Linux systems.

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By default, what does useradd NOT create?

Username

Home directory

User ID

Group

On many systems, useradd does not create a home directory by default unless the -m option is specified or configured otherwise in /etc/login.defs.

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Which option with useradd creates a home directory?

-d

-m

-s

-h

The -m flag ensures that the user's home directory is created during account creation.

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Which command is used to set or change a user password?

passwd -

passwd

chpasswd

setpass

The passwd command allows you to change your own password or, if root, another user's password.

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Which command shows user ID and group ID details?

whoami

id

users

groups

The id command displays user identity information, including UID, GID, and group memberships.

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Which group provides sudo access on CentOS / RHEL?

sudo

wheel

admin

root

In RHEL-based systems (CentOS, Fedora), the wheel group is typically used to grant sudo privileges.

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Which group provides sudo access on Ubuntu?

sudo

wheel

admin

root

In Debian-based systems (Ubuntu), the sudo group is dedicated to granting administrative rights.

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Which command adds a user to a group?

groupadd

usermod -aG

adduser

chgrp

usermod -aG groupname username appends (add) the user to the specified group without removing them from other groups.

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Which command verifies group membership of a user?

whoami

id username

groupsadd

passwd

Running id username lists all the groups that the specified user belongs to.

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Which command removes a user from a group?

gpasswd -d username groupname

userdel groupname

delgroup username

usermod -d

gpasswd -d is specifically used to delete a user from a group.

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Which command deletes a user account but keeps home directory?

userdel username

userdel -r username

deluser -h

rm user

userdel username removes the user account but preserves the home directory and mail spool unless -r is used.

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Which command deletes a user account and home directory?

userdel username

userdel -r username

deluser username

rm -rf /home/username

The -r (remove) option with userdel ensures that the user's home directory and mail spool are also deleted.

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Which command allows editing system files with root privileges?

vi file

sudo vi file

su vi file

root vi file

Prefixing the command with sudo executes it with root privileges, which is necessary for editing system configuration files.

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Which file defines sudo permissions?

/etc/passwd

/etc/group

/etc/sudoers

/etc/profile

The /etc/sudoers file controls which users can run what commands as which users (and machines).

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Which command should be used to safely edit the sudoers file?

vi /etc/sudoers

visudo

nano sudoers

sudoedit

visudo locks the sudoers file against multiple simultaneous edits, provides basic sanity checks, and checks for syntax errors.

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