apt (Debian/Ubuntu) basics in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of apt list --installed | grep bash?

You run the command apt list --installed | grep bash on a Debian/Ubuntu system. What will this command output?

Linux CLI

apt list --installed | grep bash

A Lists all available packages containing 'bash' but not necessarily installed ones.

B Shows an error: 'bash' is not a valid option for apt list.

C Outputs nothing because 'grep' is not installed by default.

D Lists all installed packages whose names contain 'bash', showing their versions and status.

💡 Hint

Think about what apt list --installed does and how grep filters output.

The command apt list --installed lists all installed packages. Piping it to grep bash filters the list to only those packages whose names contain 'bash'. This shows installed bash-related packages with their versions.

💻 Command Output

intermediate

What error does this command produce: apt-get install --dry-run nonexistent-package?

You try to simulate installing a package that does not exist using apt-get install --dry-run nonexistent-package. What error message or output will you get?

Linux CLI

apt-get install --dry-run nonexistent-package

A E: Unable to locate package nonexistent-package

B Simulates installation successfully with no errors

C Syntax error: unknown option '--dry-run'

D Warning: Package already installed

💡 Hint

Think about what happens when you try to install a package that does not exist in the repositories.

The apt-get command with --dry-run simulates installation. If the package does not exist, apt-get reports E: Unable to locate package error.

🔧 Debug

advanced

Why does this command fail: apt update && apt upgrade -y run as a normal user?

You run apt update && apt upgrade -y as a normal user (not root). The command fails. What is the reason?

Linux CLI

apt update && apt upgrade -y

A The system must be offline for 'apt upgrade' to work.

B Normal users do not have permission to update package lists or upgrade packages; root privileges are required.

C The '-y' option is invalid and causes the command to fail.

D The command syntax is incorrect; 'apt upgrade' must come before 'apt update'.

💡 Hint

Think about who can change system packages and update system files.

Updating package lists and upgrading packages require root privileges because they modify system files. Running as a normal user causes permission denied errors.

🚀 Application

advanced

How to list all packages that can be upgraded using apt?

You want to see which packages have updates available before upgrading. Which command will correctly list all upgradable packages?

A apt list --upgradable

B apt show upgradable

C apt search --upgrade

D apt-get list --upgradeable

💡 Hint

Check the official apt command options for listing upgradable packages.

The command apt list --upgradable lists all packages with available upgrades. Other options are invalid or do not exist.

🧠 Conceptual

expert

What is the effect of running apt-get clean on a Debian/Ubuntu system?

You run apt-get clean. What does this command do?

A Removes all installed packages that are no longer needed.

B Updates the package lists from the repositories.

C Deletes all cached package files from the local repository to free disk space.

D Upgrades all installed packages to the latest version.

💡 Hint

Think about what 'clean' means in the context of package management cache.

apt-get clean removes all downloaded package files (.deb) from the local cache, freeing disk space but not affecting installed packages.

Practice

1. What does the apt update command do on a Debian/Ubuntu system?

easy

A. It upgrades all installed packages to the latest version.

B. It installs new software packages.

C. It removes installed software packages.

D. It refreshes the list of available packages and their versions.

Solution

1. Step 1: Understand the purpose of apt update

   This command downloads the latest package lists from the repositories configured on the system.

2. Step 2: Differentiate from other apt commands

   Unlike install or upgrade, it does not change installed software but only refreshes package info.

3. Final Answer:

   It refreshes the list of available packages and their versions. -> Option D

4. Quick Check:

   apt update refreshes package info [OK]

Hint: Remember: update refreshes info, install adds software [OK]

Common Mistakes:

• Confusing update with install or upgrade
• Thinking update removes packages
• Running update without sudo and expecting changes

2. Which of the following is the correct syntax to install the package named curl using apt?

easy

A. apt install curl

B. apt get install curl

C. apt install -y curl

D. apt-install curl

Solution

1. Step 1: Identify the correct apt install syntax

   The basic command is apt install package_name. Adding -y automatically confirms prompts.

2. Step 2: Evaluate each option

   apt install curl is correct syntax but misses automatic confirmation. apt get install curl is incorrect syntax; it should be apt-get not apt get. apt-install curl uses invalid syntax. apt install -y curl is correct and includes -y for automation.

3. Final Answer:

   apt install -y curl -> Option C

4. Quick Check:

   Use apt install -y for automatic yes [OK]

Hint: Use -y to skip prompts during install [OK]

Common Mistakes:

• Typing 'apt get' instead of 'apt-get'
• Using hyphens incorrectly in command names
• Forgetting sudo before apt commands

3. What will be the output of the command apt search nano if the package nano is available?

medium

A. Lists packages with 'nano' in their name or description.

B. Installs the nano package immediately.

C. Removes the nano package from the system.

D. Updates the nano package to the latest version.

Solution

1. Step 1: Understand the purpose of apt search

   This command searches the package database for names or descriptions matching the search term.

2. Step 2: Analyze the command effect

   It does not install, remove, or update packages; it only lists matching packages.

3. Final Answer:

   Lists packages with 'nano' in their name or description. -> Option A

4. Quick Check:

   apt search lists matching packages [OK]

Hint: Search shows matching packages, doesn't install or remove [OK]

Common Mistakes:

• Thinking search installs packages
• Confusing search with update or upgrade
• Expecting no output if package is not installed

4. You run apt install git but get a permission denied error. What is the most likely fix?

medium

A. Run the command with sudo as sudo apt install git.

B. Use apt update before installing git.

C. Remove git first using apt remove git.

D. Restart the computer and try again.

Solution

1. Step 1: Identify cause of permission denied

   Installing packages requires administrative rights, so running without sudo causes permission errors.

2. Step 2: Apply correct command with elevated rights

   Prepend sudo to gain necessary permissions: sudo apt install git.

3. Final Answer:

   Run the command with sudo as sudo apt install git. -> Option A

4. Quick Check:

   Use sudo for system changes [OK]

Hint: Use sudo for install/remove commands [OK]

Common Mistakes:

• Trying to install without sudo
• Running update instead of fixing permissions
• Restarting without fixing command permissions

5. You want to write a script that installs vim only if it is not already installed. Which command sequence correctly checks and installs using apt?

hard

A. apt search vim && sudo apt install vim

B. if ! dpkg -l | grep -q '^ii vim '; then sudo apt install -y vim; fi

C. sudo apt install vim && echo 'vim installed'

D. dpkg -s vim || apt install vim

Solution

1. Step 1: Understand how to check if vim is installed

   Using dpkg -l lists installed packages; filtering with grep '^ii vim ' checks if vim is installed.

2. Step 2: Use conditional to install only if not installed

   The if ! ...; then ...; fi structure runs install only if vim is missing.

3. Step 3: Evaluate other options

   sudo apt install vim && echo 'vim installed' installs unconditionally. apt search vim && sudo apt install vim searches but does not check installation. dpkg -s vim || apt install vim misses sudo and may fail silently.

4. Final Answer:

   if ! dpkg -l | grep -q '^ii vim '; then sudo apt install -y vim; fi -> Option B

5. Quick Check:

   Check with dpkg, install if missing [OK]

Hint: Use dpkg -l and grep to check before install [OK]

Common Mistakes:

• Installing without checking if package exists
• Forgetting sudo in install command
• Using apt search instead of dpkg for installed check