Exploring the Power of RPM: The Red Hat Package Manager for Linux

Hello and Welcome to all Linux enthusiasts!

Today, let’s dive into an essential component of Red Hat Enterprise Linux (RHEL)—the RPM, or Red Hat Package Manager. RPM is a powerful tool that makes software management on RHEL a breeze, whether you're installing, upgrading, or uninstalling packages.

First of all, let's understand What is Red Hat Linux or RHEL (Red Hat Enterprise Linux) ?

What is Red Hat Enterprise Linux (RHEL)?

RHEL is a commercially supported, open-source Linux distribution designed by Red Hat for enterprise environments. It’s renowned for stability, security, and long-term support, making it a popular choice for organizations globally.

Why Package Managers Matter

Every Linux distribution comes with a package manager to handle software efficiently. RPM serves this purpose on RHEL, allowing you to install, update, remove, and configure software packages smoothly. For those familiar with Windows, think of RPM as akin to running .msi or .exe files for software installation but tailored for Linux.

Key Features of RPM

RPM has a well-thought-out design that simplifies package management in several powerful ways:

1. Upgradability RPM lets you upgrade individual components without reinstalling the entire OS. With in-place upgrades, it’s efficient and avoids unnecessary downtime.
2. Powerful Querying RPM supports extensive querying options. Whether you need to find a package by its name, check its version, or discover which files belong to a package, RPM has you covered.
3. System Verification Ever deleted a file accidentally? RPM’s verification feature lets you check if any important package files are missing or altered. If they are, RPM can reinstall the package while preserving your configuration changes.
4. Pristine Sources RPM allows you to work with the software's original source code alongside necessary patches and build instructions, which is invaluable for developers and system admins aiming for transparency.

Operating RPM: The Basics

RPM functions in five primary modes: installing, uninstalling, upgrading, querying, and verifying. Let’s explore these modes with examples:

To install a package, you need a package to install such as software setup. So before using any RPM packages, you must know where to find them. An Internet search returns many RPM repositories, but if you are looking for RPM packages built by Red Hat, they can be found at the following locations:

• The Red Hat Enterprise Linux CD-ROMs (iso-dvd)
• The Red Hat Errata Page available at https://www.redhat.com/apps/support/errata/
• Red Hat Network

Installing

RPM packages typically have file names like firefox-115.9.1-1.el9_3.x86_64.rpm. The file name includes the package name (firefox), version (115.9.1), release (1.el9_3), and architecture (x86_64). To install a package, log in as root and type the following command at a shell prompt:

rpm -ivh firefox-115.9.1-1.el9_3.x86_64.rpm        

-i : install the package

-v : print verbose information, normally routine progress messages will be displayed.

-h : Print 50 hash marks as the package archive is unpacked. Use with -v|--verbose for a nicer display.

If a package of the same name and version is already installed, during the installation, the following output is displayed:

Preparing...               ########################################### [100%]

package firefox-115.9.1-1.el9_3.x86_64 is already installed        

However, if you want to install the package anyway, you can use the --replacepkgs option, which tells RPM to ignore the error:

rpm -ivh --replacepkgs firefox-115.9.1-1.el9_3.x86_64.rpm        

Upgrading

To upgrade a package, use -U:

rpm -Uvh package-name        

-U : upgrade the package

Querying

The RPM database stores information about all RPM packages installed in your system. It is stored in the directory /var/lib/rpm/, and is used to query what packages are installed, what versions each package is, and any changes to any files in the package since installation, among others.

To query this database, use the -q option. The rpm -q package_name command displays the package name, version, and release number of the installed package package_name.

rpm -q package_name        

If you want to query a specific packages, for instance, firefox, use below command:

You can also use the following Package Selection Options with -q to further refine or qualify your query:

• -a — queries all currently installed packages.

• -f <filename> — queries the RPM database for which package owns f<filename> . When specifying a file, specify the absolute path of the file (for example, rpm -qf /bin/ls ).

• -p <packagefile> — queries the uninstalled package <packagefile>.

There are a number of ways to specify what information to display about queried packages. The following options are used to select the type of information for which you are searching. These are called Package Query Options.

• -i : displays package information including name, description, release, size, build date, install date, vendor, and other miscellaneous information.

• -l (lowercase L) : displays the list of files that the package contains.

• -s displays the state of all the files in the package.
• -d displays a list of files marked as documentation (man pages, info pages, READMEs, etc.).

• -c displays a list of files marked as configuration files. These are the files you edit after installation to adapt and customize the package to your system (for example, sendmail.cf, passwd, inittab, etc.).

Uninstalling

You can use -e option to rpm command to uninstall or erase the package.

rpm -e package-name        

Verifying

Package verification ensures that your system files remain as they were intended, detecting any accidental changes or deletions. This is especially valuable for maintaining system stability and security.

Verification in RPM compares key details of the files in an installed package with the original files from the package. It checks aspects such as:

• File size
• MD5 checksum
• Permissions
• File type
• Ownership (owner and group)

This comparison helps you confirm that no critical files have been modified or corrupted, protecting the integrity of your system.

To verify a package containing a particular file:

rpm  -Vf  /usr/bin/firefox        

To verify ALL installed packages throughout the system:

rpm -Va        

To verify an installed package against an RPM package file:

rpm -Vp  firefox-115.9.1-1.el9_3.x86_64.rpm        

If everything checks out, RPM verification produces no output. If discrepancies are found, RPM will display them, giving you insights into which files have changed and how. This can include permission changes, modifications, or even missing files.

With RPM’s verification tools, you can confidently monitor your system's health, quickly spotting and addressing any issues.

Why RPM Matters for You

Mastering RPM is key to managing a Red Hat system effectively. With skills in RPM, you'll be able to troubleshoot, verify package integrity, and ensure your system is up-to-date—all essential skills for any Linux professional.

- Mehul Gupta