Book Image

Oracle Linux Cookbook

By : Erik Benner, Erik B. Thomsen, Jonathan Spindel
Book Image

Oracle Linux Cookbook

By: Erik Benner, Erik B. Thomsen, Jonathan Spindel

Overview of this book

Discover the power of Oracle Linux 8, the free and enterprise-grade Linux distribution designed for use in any environment, with this recipe-style book. Starting with instructions on how to obtain Oracle Linux for both X86 and ARM-based platforms, this book walks you through various installation methods, from running it as a Windows service to installing it on a Raspberry Pi. It unravels advanced topics such as system upgrades using Leapp for major version transitions and using a PXE server and kickstart files for more advanced installations. The book then delves into swapping kernels to take advantage of Oracle’s UEK, exploring boot options, managing software with DNF, and achieving high availability. Detailed recipes involving security topics will assist with tasks such as data encryption, both at rest and in motion. For developers, it offers guidance on building RPM files, using Docker and Podman in a containerized environment, working with AppStreams, and more. For large-scale deployments, the book introduces Oracle Linux Automation Manager for enterprise-level Ansible utilization, from setting up the Ansible server to basic playbook writing. Finally, you’ll discover strategies for cloud migration. By the end of this book, you’ll possess a comprehensive toolkit that will elevate your skills as a Linux administrator.
Table of Contents (16 chapters)

Using the DNF time machine

DNF has a time machine built into it! This isn’t just a way to look back through the cosmos; it actually allows you to see the history of what was installed and also allows you to roll back a single change, or all changes up to a point.

Getting ready

To do this, you will need a test system, running Oracle Linux 8, with access to an RPM repo.

How to do it…

When DNF installs software, it keeps a history of all the actions performed. This includes upgrades to the software, installed software, and removal of the software. The dnf history command shows this history:

Figure 5.3 – The dnf history command

Figure 5.3 – The dnf history command

There are five columns – ID, Command line, Date and time, Action(s), and Altered:

  • ID: This is the identifier for the history, and is used in commands that will show info, roll back, undo, or store a transaction
  • Command line: This is the option passed to DNF when the command was run...