Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

By : Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty
2 (2)
Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

2 (2)
By: Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty

Overview of this book

With Red Hat Enterprise Linux 9 becoming the standard for enterprise Linux used from data centers to the cloud, Linux administration skills are in high demand. With this book, you’ll learn how to deploy, access, tweak, and improve enterprise services on any system on any cloud running Red Hat Enterprise Linux 9. Throughout the book, you’ll get to grips with essential tasks such as configuring and maintaining systems, including software installation, updates, and core services. You’ll also understand how to configure the local storage using partitions and logical volumes, as well as assign and deduplicate storage. You’ll learn how to deploy systems while also making them secure and reliable. This book provides a base for users who plan to become full-time Linux system administrators by presenting key command-line concepts and enterprise-level tools, along with essential tools for handling files, directories, command-line environments, and documentation for creating simple shell scripts or running commands. With the help of command line examples and practical tips, you’ll learn by doing and save yourself a lot of time. By the end of the book, you’ll have gained the confidence to manage the filesystem, users, storage, network connectivity, security, and software in RHEL 9 systems on any footprint.
Table of Contents (26 chapters)
1
Part 1 – Systems Administration – Software, User, Network, and Services Management
9
Part 2 – Security with SSH, SELinux, a Firewall, and System Permissions
14
Part 3 – Resource Administration – Storage, Boot Process, Tuning, and Containers
21
Part 4 – Practical Exercises

Working with GRUB, the bootloader, and the initrd system images

Once the pre-boot execution has been completed, the system will be running the GRUB bootloader.

GRUB has the mission to load the main file of an operating system, the kernel, pass parameters and options to it, and load the initial RAM disk, also known as initrd.

GRUB can be installed using the grub2-install command. We will need to know which disk device will be used to boot, in this case, /dev/vda:

[root@rhel-instance ~]# grub2-install /dev/vda
Installing for i386-pc platform.
Installation finished. No error reported.

Important Note

You should point grub-install to the disk you will use to boot the system; this is the same one that you configured in the BIOS/UEFI to boot from.

This is intended to be used to manually rebuild a system or to fix a broken boot.

GRUB files are stored in /boot/grub2. The main configuration file is /boot/grub2/grub.cfg. However, if you take a close look at this file, you...