sudo for elevated privileges in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the sudo command do in Linux?

sudo lets a user run commands with the security privileges of another user, usually the superuser (root). It is used to perform tasks that require higher permissions.

beginner

Why should you be careful when using sudo?

Using sudo gives you powerful access that can change or damage system files. Mistakes can cause system problems or security risks.

beginner

How do you run a command with sudo?

Simply type sudo before the command. For example, sudo apt update runs the update command with elevated privileges.

beginner

What happens if you enter the wrong password when using sudo?

The command will not run. sudo asks for your user password to confirm your identity. If wrong, it denies access.

intermediate

What is the difference between su and sudo?

su switches the user to another user account (often root) and requires that user's password. sudo runs a single command with elevated rights using your own password.

What is the main purpose of the sudo command?

A Change file permissions

B Switch to a different user account permanently

C List files in a directory

D Run commands with higher privileges

sudo allows running commands with elevated privileges, usually as root.

Which password does sudo ask for when you run a command?

A Root user password

B No password is required

C Your own user password

D The password of the last logged-in user

sudo asks for your own password to verify your identity.

What happens if you enter the wrong password when using sudo?

A Access is denied and the command does not run

B You get logged out

C The command runs anyway

D The system restarts

Wrong password means sudo denies access and does not run the command.

Which command runs a single command with elevated privileges without switching users?

A su

B sudo

C chmod

D passwd

sudo runs a single command with elevated privileges.

Why is it important to use sudo carefully?

A It can cause system damage if misused

B It disables the internet

C It deletes your user account

D It can slow down your computer

Using sudo incorrectly can damage system files or cause security issues.

Explain what sudo does and why it is used in Linux.

Think about how you get permission to do special tasks on your computer.

Describe the difference between sudo and su commands.

One lets you do one thing as admin, the other changes who you are.

Practice

1. What is the main purpose of using sudo in Linux?

easy

A. To create a new user account

B. To switch to another user account permanently

C. To list files in a directory

D. To run commands with higher privileges than a normal user

Solution

1. Step 1: Understand what sudo does

   sudo allows a user to run commands with elevated privileges, usually root access.

2. Step 2: Compare options with sudo purpose

   Only To run commands with higher privileges than a normal user describes running commands with higher privileges, which matches sudo's main use.

3. Final Answer:

   To run commands with higher privileges than a normal user -> Option D

4. Quick Check:

   sudo = elevated privileges [OK]

Hint: sudo means run as superuser or admin [OK]

Common Mistakes:

• Confusing sudo with user switching commands
• Thinking sudo creates users
• Assuming sudo lists files

2. Which of the following is the correct syntax to run the command apt update with elevated privileges?

easy

A. sudo apt update

B. apt sudo update

C. sudo -u apt update

D. apt update sudo

Solution

1. Step 1: Recall the correct sudo syntax

   The correct syntax is sudo [command], so sudo apt update is valid.

2. Step 2: Check each option

   Options A, B, and D place sudo incorrectly or misuse flags.

3. Final Answer:

   sudo apt update -> Option A

4. Quick Check:

   sudo before command = correct syntax [OK]

Hint: Put sudo before the command to elevate it [OK]

Common Mistakes:

• Placing sudo after the command
• Using sudo with wrong flags
• Mixing sudo with user flags incorrectly

3. What will be the output of the command sudo whoami if run by a normal user?

medium

A. root

B. sudo

C. normal user name

D. Permission denied

Solution

1. Step 1: Understand what whoami does

   whoami prints the current user's name.

2. Step 2: Effect of sudo on whoami

   Running sudo whoami runs the command as root, so it prints root.

3. Final Answer:

   root -> Option A

4. Quick Check:

   sudo changes user to root for command [OK]

Hint: sudo runs command as root user [OK]

Common Mistakes:

• Expecting normal username output
• Thinking sudo prints 'sudo'
• Assuming permission denied without sudo

4. You try to run sudo apt-get update but get the error: sudo: command not found. What is the most likely cause?

medium

A. You typed the command incorrectly

B. You are not logged in as root

C. The sudo package is not installed or not in PATH

D. You need to use su instead of sudo

Solution

1. Step 1: Analyze the error message

   sudo: command not found means the system cannot find the sudo program.

2. Step 2: Identify common reasons

   This usually happens if sudo is not installed or its location is missing from the PATH environment variable.

3. Final Answer:

   The sudo package is not installed or not in PATH -> Option C

4. Quick Check:

   command not found = missing sudo or PATH [OK]

Hint: command not found means sudo missing or PATH wrong [OK]

Common Mistakes:

• Assuming user login affects sudo command presence
• Thinking command typo causes 'command not found'
• Confusing su and sudo usage errors

5. You want to run a script backup.sh that requires root permissions. Which command correctly runs it with sudo and ensures the script's environment variables are preserved?

hard

A. sudo ./backup.sh

B. sudo -E ./backup.sh

C. sudo -u root ./backup.sh

D. sudo --preserve-env=ALL ./backup.sh

Solution

1. Step 1: Understand environment preservation with sudo

   By default, sudo resets environment variables for security. The -E flag preserves the user's environment.

2. Step 2: Evaluate options for preserving environment

   sudo -E ./backup.sh uses -E which preserves environment variables. sudo --preserve-env=ALL ./backup.sh uses a longer form but --preserve-env=ALL is less common and may not be supported everywhere.

3. Final Answer:

   sudo -E ./backup.sh -> Option B

4. Quick Check:

   sudo -E preserves environment variables [OK]

Hint: Use sudo -E to keep environment variables [OK]

Common Mistakes:

• Forgetting environment variables reset by sudo
• Using sudo without -E loses variables
• Confusing -u root with environment preservation