yum/dnf (RHEL/CentOS) basics in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this command?

You run the command yum list installed httpd on a RHEL system. What will this command output?

Linux CLI

yum list installed httpd

A Lists the installed version of the httpd package if installed, or shows 'Error: No matching Packages to list'

B Installs the httpd package

C Removes the httpd package

D Updates the httpd package to the latest version

💡 Hint

Think about what 'list installed' means in yum.

The command 'yum list installed httpd' shows if the httpd package is installed and its version. It does not install, remove, or update packages.

💻 Command Output

intermediate

What happens when you run this command?

What is the result of running dnf clean all on a CentOS system?

Linux CLI

dnf clean all

A Installs all available updates

B Removes all installed packages

C Removes all cached package data and metadata, freeing disk space

D Lists all enabled repositories

💡 Hint

Think about what 'clean' means in package managers.

'dnf clean all' deletes all cached data including metadata and packages, which helps free disk space and forces fresh downloads next time.

📝 Syntax

advanced

Which command correctly installs a package and its dependencies?

You want to install the package 'vim' along with all its dependencies on a RHEL system. Which command is correct?

A dnf update vim

B yum get vim

C dnf remove vim

D yum install vim

💡 Hint

The command should add a package, not remove or update it.

'yum install vim' installs the vim package and all required dependencies. 'yum get' is invalid, 'dnf remove' deletes packages, and 'dnf update' upgrades existing packages.

🚀 Application

advanced

How to check which repository provides a package?

You want to find out which enabled repository provides the package 'curl' on a CentOS system. Which command will show this information?

A yum list installed curl

B dnf repoquery --whatprovides curl

C dnf clean all

D yum remove curl

💡 Hint

Look for a command that queries repositories for package info.

'dnf repoquery --whatprovides curl' lists which repository supplies the curl package. Other commands list installed packages, clean cache, or remove packages.

🔧 Debug

expert

Why does this command fail with 'No match for argument' error?

You run yum install httpd-tools-2.4.6 but get the error 'No match for argument: httpd-tools-2.4.6'. What is the most likely reason?

Linux CLI

yum install httpd-tools-2.4.6

A The package name should not include the version number; use 'yum install httpd-tools' instead

B The package is already installed, so yum refuses to install it again

C The system is offline and cannot reach repositories

D The command syntax is incorrect; 'yum install -v httpd-tools-2.4.6' is required

💡 Hint

Think about how yum expects package names.

Yum expects package names without version numbers. Including the version causes no match error. To install a specific version, a different syntax is needed.

Practice

1. What is the primary purpose of the yum or dnf command on RHEL/CentOS systems?

easy

A. To configure network settings

B. To monitor system hardware performance

C. To edit text files in the terminal

D. To manage software packages by installing, updating, or removing them

Solution

1. Step 1: Understand the role of yum/dnf

   yum and dnf are package managers used to handle software packages on RHEL/CentOS.

2. Step 2: Identify the correct function

   They allow users to install, update, and remove software easily.

3. Final Answer:

   To manage software packages by installing, updating, or removing them -> Option D

4. Quick Check:

   yum/dnf = software package management [OK]

Hint: yum/dnf commands control software packages [OK]

Common Mistakes:

• Confusing yum/dnf with system monitoring tools
• Thinking yum/dnf edits files or network settings
• Mixing yum/dnf with text editors

2. Which of the following is the correct syntax to install a package named httpd using dnf with automatic yes to prompts?

easy

A. dnf install httpd y

B. dnf -y install httpd

C. dnf -y httpd install

D. dnf httpd install -y

Solution

1. Step 1: Understand dnf command syntax

   The -y option should come immediately after dnf to apply to the entire command.

2. Step 2: Check the order of arguments

   Correct syntax is dnf -y install httpd to install with automatic yes.

3. Final Answer:

   dnf -y install httpd -> Option B

4. Quick Check:

   dnf -y install package = correct syntax [OK]

Hint: Place -y right after dnf for automatic yes [OK]

Common Mistakes:

• Putting -y after the package name
• Mixing argument order causing syntax errors
• Using incorrect command order

3. What will be the output of the command dnf list installed | grep bash on a system where bash is installed?

medium

A. A list of all packages except bash

B. An error saying 'bash not found'

C. A list line showing the bash package details

D. No output at all

Solution

1. Step 1: Understand the command components

   dnf list installed lists all installed packages; piping to grep bash filters lines containing 'bash'.

2. Step 2: Predict output if bash is installed

   Since bash is installed, the output will show the bash package line.

3. Final Answer:

   A list line showing the bash package details -> Option C

4. Quick Check:

   dnf list installed | grep bash = bash package line [OK]

Hint: grep filters output lines containing the keyword [OK]

Common Mistakes:

• Expecting an error if package exists
• Thinking grep excludes matching lines
• Assuming no output means package installed

4. You run sudo yum install -y nginx but get an error: Could not find a valid baseurl for repo. What is the most likely cause?

medium

A. Network connection or repository configuration issue

B. The nginx package does not exist

C. You forgot to use sudo

D. The command syntax is incorrect

Solution

1. Step 1: Analyze the error message

   The error 'Could not find a valid baseurl for repo' means yum/dnf cannot reach the repository URL.

2. Step 2: Identify common causes

   This usually happens due to network issues or wrong repo configuration, not package absence or syntax errors.

3. Final Answer:

   Network connection or repository configuration issue -> Option A

4. Quick Check:

   Repo baseurl error = network or repo config problem [OK]

Hint: Check network and repo config if baseurl error appears [OK]

Common Mistakes:

• Assuming package missing causes baseurl error
• Ignoring need for network access
• Blaming command syntax for repo errors

5. You want to automate updating all packages on a CentOS system without prompts. Which command should you use?

hard

A. sudo dnf update -y

B. sudo yum update

C. sudo dnf install -y

D. sudo yum remove -y

Solution

1. Step 1: Identify the command to update all packages

   dnf update or yum update updates all installed packages.

2. Step 2: Add automation to avoid prompts

   Adding -y automatically answers yes to prompts, enabling automation.

3. Final Answer:

   sudo dnf update -y -> Option A

4. Quick Check:

   dnf update -y = automated full update [OK]

Hint: Use -y with update to automate package upgrades [OK]

Common Mistakes:

• Using install instead of update to upgrade packages
• Forgetting sudo for permission
• Using remove instead of update