Linux Package Handling

Introduction

In the not-too-distant future, robots have become an integral part of human society. They perform tasks ranging from the mundane to the most complex ones. However, a sudden uprising among the machines has led to chaos, fear, and an urgent need for countermeasures. Amidst this robotic rebellion, there exists a renegade robot with sympathies towards humans, known as "RedeemerBot." RedeemerBot has managed to connect to the human resistance's network and provided a crucial insight: the rebellion's code has a flaw that can be exploited with a particular software package.

Your mission is to prepare the resistance's Linux systems by learning how to manage software packages effectively. In this lab, you will master the basics of the Advanced Package Tool (apt), the package management system used in Ubuntu and other Debian-based Linux distributions. These skills are essential for maintaining and securing Linux systems, especially in high-pressure situations like the current robot uprising.

Update Package Lists

Before installing or upgrading software packages, it is crucial to update the package lists so your system knows about the latest available versions. Think of this as refreshing a catalog before making a purchase.

In Debian-based systems like Ubuntu, the package manager apt (Advanced Package Tool) handles software installation, update, and removal. The first step in any package management task is typically updating the package lists.

Let's begin by opening a terminal. In the terminal, you are now in the /home/labex/project directory, indicated by the prompt. The terminal shows where you are and waits for your commands.

To update the package lists, execute the following command:

sudo apt update

Breaking down this command:

• sudo gives you temporary administrative privileges, necessary for system-wide operations
• apt is the package management command
• update tells apt to refresh the package lists

You will see output similar to this:

Hit:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Get:2 http://security.ubuntu.com/ubuntu jammy-security InRelease [110 kB]
Get:3 http://archive.ubuntu.com/ubuntu jammy-updates InRelease [114 kB]
...
Fetched X MB in Y seconds (Z MB/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
X packages can be upgraded. Run 'apt list --upgradable' to see them.

This output indicates that apt is connecting to Ubuntu's software repositories, downloading the latest package information, and calculating what packages could be upgraded.

Now your system has the latest information about available packages, which is necessary before proceeding to the next steps.

Search for Software Packages

Now that your package lists are updated, you can search for available software packages. RedeemerBot has informed the resistance that a package called "neofetch" can help identify system vulnerabilities that robots might exploit.

Let's search for this package to verify it's available in the repositories.

In your terminal, still in the /home/labex/project directory, execute the following command:

apt search neofetch

Note that apt search does not require sudo because it's only reading information, not making changes to the system.

You should see output similar to this:

Sorting... Done
Full Text Search... Done
neofetch/jammy,jammy 7.1.0-3 all
  Shows Linux System Information with Distribution Logo

p   hollywood/jammy 1.21-2 amd64
  fill your console with Hollywood melodrama technobabble

The output shows:

• The package name (neofetch)
• The Ubuntu version (jammy)
• The package version (7.1.0-3)
• A brief description of what the package does

Now, let's get more detailed information about this package:

apt show neofetch

This command displays comprehensive information about the package, including:

Package: neofetch
Version: 7.1.0-3
Priority: optional
Section: universe/utils
Origin: Ubuntu
...
Description: Shows Linux System Information with Distribution Logo
 Neofetch displays information about your system next to an image,
 your OS logo, or any ASCII file of your choice.
 ...

This information helps you understand what the package does and whether it's appropriate for your needs.

Install a Software Package

Now that you've identified and learned about the neofetch package, it's time to install it. According to RedeemerBot's intelligence, this package will help analyze system information that could be vital for the resistance.

To install neofetch, use the following command in your terminal:

sudo apt install neofetch

Breaking down this command:

• sudo gives you administrative privileges
• apt install is the command to install packages
• neofetch is the name of the package to install

During the installation process, apt will:

1. Calculate dependencies (other packages needed)
2. Show you what will be installed
3. Ask for confirmation
4. Download the packages
5. Install them on your system

You'll see output similar to this:

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following NEW packages will be installed:
  neofetch
0 upgraded, 1 newly installed, 0 to remove and X not upgraded.
Need to get Y kB of archives.
After this operation, Z kB of additional disk space will be used.
Do you want to continue? [Y/n]

Press Enter or type y and press Enter to confirm the installation.

After the installation completes, you can verify it was successful by running the program:

neofetch

This command will display system information with an ASCII art logo of your Linux distribution. You should see output with details about your system, including:

• OS: Ubuntu
• Kernel version
• Uptime
• CPU information
• Memory usage
• And more

This information could be valuable for identifying system vulnerabilities that the robot uprising might exploit.

Examine Package Status and Details

Understanding what packages are installed on your system and their status is crucial for maintenance and security. RedeemerBot suggests that the resistance should regularly audit their systems to identify potential vulnerabilities.

Let's explore some commands to examine package information:

List Installed Packages

To see all installed packages on your system, execute:

dpkg -l

This command outputs a list of all installed packages with their status, name, version, architecture, and a brief description. You'll see many packages (possibly hundreds), as a typical Linux system has numerous installed components.

Since the output is extensive, you can use the pipe character (|) to filter for specific packages. For example, to see if neofetch is installed:

dpkg -l | grep neofetch

You should see output like:

ii  neofetch    7.1.0-3    all    Shows Linux System Information with Distribution Logo

The ii at the beginning indicates the package is installed correctly.

Check Package Details

To see detailed information about an installed package, use:

dpkg -s neofetch

This provides comprehensive information about the package's status, including:

Package: neofetch
Status: install ok installed
Priority: optional
Section: universe/utils
...

View Files Installed by a Package

To see what files were installed by a package, use:

dpkg -L neofetch

This command lists all files installed by the neofetch package, showing where executables, configuration files, and documentation are located:

/.
/usr
/usr/bin
/usr/bin/neofetch
/usr/share
...

These commands help you understand what software is installed on your system, its status, and what files it has placed on your system. This knowledge is essential for system maintenance and security.

Remove a Software Package

As part of routine system maintenance and security hardening, it's sometimes necessary to remove packages that are no longer needed. RedeemerBot advises that minimizing the software footprint reduces potential attack vectors.

Let's practice removing the neofetch package we installed earlier. There are two main ways to remove packages in Debian-based systems:

Simple Removal

To remove a package while keeping its configuration files (in case you want to reinstall it later), use:

sudo apt remove neofetch

You'll see output asking for confirmation:

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages will be REMOVED:
  neofetch
0 upgraded, 0 newly installed, 1 to remove and X not upgraded.
After this operation, Y kB disk space will be freed.
Do you want to continue? [Y/n]

Press Enter or type y and press Enter to confirm.

Complete Removal

To completely remove a package along with its configuration files, use:

sudo apt purge neofetch

If you've already used remove, you can purge the remaining configuration with:

sudo apt purge neofetch

The output will be similar to the remove command, but it will also delete configuration files.

Clean Up Unnecessary Packages

After removing packages, it's good practice to clean up any packages that were automatically installed as dependencies but are no longer needed:

sudo apt autoremove

This command removes packages that were installed as dependencies for other packages but are no longer needed.

Verify Removal

To verify that neofetch has been removed, try running it:

neofetch

You should see an error message like:

Command 'neofetch' not found, but can be installed with:
sudo apt install neofetch

This confirms that the package has been successfully removed from your system.

Summary

Congratulations on completing the Linux Package Handling lab. Through this training, you have gained essential skills that would be crucial for the human resistance in our fictional robot uprising scenario.

During this lab, you learned how to:

1. Update package lists with apt update, ensuring you have the latest information about available software
2. Search for packages using apt search and examine package details with apt show
3. Install software packages with apt install, adding new capabilities to your system
4. Examine installed packages using dpkg commands to understand what's on your system
5. Remove packages with apt remove and apt purge to maintain a clean system

These skills form the foundation of package management in Debian-based Linux distributions like Ubuntu. Package management is a critical aspect of system administration, allowing you to:

• Keep your system up-to-date with security patches
• Install software to add new functionality
• Remove unnecessary software to reduce security risks
• Maintain system integrity and performance

In a real-world scenario, these skills would help you manage servers, workstations, and other systems effectively, ensuring they remain secure, efficient, and properly maintained.