Linux Package Management

When managing software pacakge on Linux systems, it’s important to understand the distinction between low-level and high-level package management tools.

Low-Level Tool: Direct Package Operations

This commands interacts directly with RPM package files, allowing users to perform basic package operations independent of online repositories or additional dependency handling.

Key Characteristics:

• No automatic dependency resolution.
• Operates solely on local .rpm files or installed packages.
• Suitable for advanced users or situations requiring precise control.

High-Level Tool: Handling Repositories and Dependency Management

These tools build on top of basic capabilities of rpm/dpkg and add robust package management features. Key Characteristcs:

• Keeps logs (transaction history)of installs, removals, and updates, enabling rollback when needed.
• Search, enable or disable software repositories as software sources.
• Update all or specific packages with a single command, pulling updates from repositories.
• Detect and resolve package repositories, fetching any required additional packages from configured repositories.
• Automatically download from repositories instead of using local packages.

Install a Pacakge

Using Local Package Tool

1. rpm Package Manager

rpm tool is used for handling package operations using an .rpm file

sudo rpm -i dummy-1.0.0-1.x86_64.rpm

• dummy: The software package name.
• 1.0.0: Version of packaged software.
• 1: The number of times this software version has been packaged; increments each time for packaging or rebuiding changes. (first packaging/build iteration of this version)
• x86_64: The hardware architecture.

2. dpkg Package Manager

dpkg tool is used for handling package operations in Debian based distros.

sudo foo_1.0-1_amd64.deb

Using Package Manager

Package managers such as dnf or yum automatically pulling packages from repositories to install.

sudo dnf install dummy #for rpm-based
sudo apt install dummy #for deb-based

• dnf/apt install package_name is enough to download and install the package.

They automatically resolve and install dependencies by pulling packages from online repositories, in case it needs to install dependencies.

Upgrade a Package

Using Local Package Tool

1. rpm Package Manager

Upgrade to a new version (or) install the package if not present.

rpm -Uvh dummy-1.1.0-1.x86_64.rpm

• Ensure you have the same package name with different versions.

2. dpkg Package Manager

Use -i flag to install, overwriting, and upgrading package.

dpkg -i foo_1.1.0-1_amd64.deb

Using Package Manager

sudo dnf update
sudo apt update

It updates the existing package in the system with the updated one, and it also handles dependencies automatically. Especially, there’s no need to reboot to apply the changes across the system.

Remove a Pacakge

Using Local Package Tool

1.rpm Package Manager

sudo rpm -e package_name

• Erase (remove) package by name.
• If multiple matches exist, use --allmatches.

2. dpkg Package Manger

sudo dpkg -r package_name

• Removes a package, but leaves configuration files.

sudo dpkg -P package_name
# or 
sudo dpkg --purge package_name

• Purges the pacakge and removes configuration files as well.

Using Package Manager

#rpm
sudo dnf remove package_name
# deb
sudo apt remove pacakge_name
sudo apt purge package_name

Query a Package

Using Local Package Tool

Notes:

• The apt-cache depends foo command is often used for querying dependencies in APT-based systems.
• Configuration files and documentation location conventions may vary by package, but are usually under /etc and /usr/share/doc respectively.
• Both dpkg and dpkg-query can be used for querying the DEB database; apt and apt-cache are higher-level tools.

Using Package Manager

#for queries on package dependencies and repo info
#RPM based
sudo dnf info package_name

#Debian based
sudo apt show package_name
sudo apt-cache depends
sudo apt-cache rdepends

Verifying a Pacakge

RPM-based Systems

• rpm --checksig verifies the authenticity and integrity of RPM file before installation
• rpm -V checks that files installed match what’s recorded in RPM database.
• rpm -Vp can verify a package file against itself; doesn’t require installation.

Debian-based Systems

• debsums is the most common tool for verifying checksums of installed files.
• dpkg-sig --verify checks signatures for package files.

Clean-Up and Maintenance

Transaction Management

Rollback and History (dnf/yum)

Why this is useful:

• Transaction history lets you track all changes made to your system by dnf or yum.
• undo and rollback allow you to reverse package updates or removals easily, which is very helpful when troubleshooting or recovering from a problematic change.

Example Workflow:

1. See transaction history:

   sudo dnf history list
   

2. If you spot a problematic update (e.g., with ID 25), undo just that transaction:

   sudo dnf history undo 25
   

3. Or, to roll back all changes up to just after transaction 22:

   sudo dnf history rollback 22
   

Note:

• Transactions are listed with unique IDs.
• yum (on older systems) supports similar commands: yum history, yum history undo, yum history rollback.

Miscellaneous Operations

These are the questions, that I got when I started experimenting with package managements, so let me write this in my own terms.

1. What would you do if you get any error such as “package is already installed”, but you want to reinstall it anyway?

• Use --replacepkgs to Install the packages even if some of them are already installed on this system
• Use --replacefiles to Install the packages even if they replace files from other, already installed, packages.
• Use --force to aggressively install the package, which combines --replacepkgs and --replacefiles.

sudo rpm -ivh --replacepkgs hayase-6.4.13-1.fc42.x86_64.rpm 
sudo rpm -ivh --replacefiles hayase-6.4.13-1.fc42.x86_64.rpm # replace files
#or aggrevise reinstall
sudo rpm -ivh --force hayase-6.4.13-1.fc42.x86_64.rpm 

For dnf:

sudo dnf reinstall package

2. How do you resolve a broken package dependency?

In Debian:

sudo apt-get install -f
#or
sudo apt --fix-broken install

In RPM:

#to fix broken dependencies
sudo dnf check #check for problems in package database
sudo dnf check-upgrade
#to fix issues
sudo dnf distro-sync

3. Manage Package Repositories

In RPM based: This follows a different approach by installing a .rpm file:

Terminal command:

sudo dnf install https://mirrors.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm 
sudo dnf install https://mirrors.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm

• After the installation, the repository will be added under /etc/yum.repos.d and you verify it by using ll /etc/yum.repos.d.

In Debian based: This is the traditional way of adding a new package repositories to Debian Linux.

• The available repositories are listed in sources.list under /etc/apt.

Open the file in editor of your choice:

sudo nvim /etc/apt/source.list

Now we can add the repository here, by following this syntax:

deb [repo URL] [distribution] [component(s)]

Lastly, update to make the changes take effect:

sudo apt update

4. What are Held and Pinned packages?

Held packges are configured to NOT be automatically upgraded by the system package manager during the routine updates.

• This keeps them locked at their current version until it’s manually updated.
  • Debian based:

    #using high level tool
    sudo apt-mark hold btop #hold the packge
    apt-mark showhold # list all the hold packages
    sudo apt-mark unhold btop #unhold the package
    

    #using low level tool
    dpkg --get-selections | grep hold # to list 
    dpkg --get-selections | grep install
    

Pinned packages refers to controlling which package version is installed or kept by specifying rules, typically using the APT preferences system.

• Pinning can select specific versions, repositories, or releases as the source for certain pacakges, and can also prevent upgrades.

  • RPM based: Install dnf-plugins-core package

    sudo dnf versionlock add btop # add btop to versionlock list
    sudo dnf versionlock list # list version-locked packages
    sudo dnf versionlock delete btop # remove btop from versionlock list