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Archive and Backup

Archiving and backing up files in Linux is essential for data protection and management. Various tools and commands can help you achieve this, including tar, gzip, bzip2, and xz.

Automated Installations

Automated installations help streamline the deployment process by using predefined configurations, making it easier to manage and maintain multiple systems.

Bash Scripts

Bash scripts automate tasks by executing commands in a specific order, making them powerful tools for automating repetitive tasks, managing system configurations, and performing complex operations efficiently in Unix-like operating systems.

Basic Installation

There are various ways to setup Red Hat Enterprise Linux (RHEL) for your personal lab:

Cockpit

Cockpit is a server administration tool sponsored by Red Hat, focused on providing a modern-looking and user-friendly interface to manage and administer servers.

Copying across Host and Guest Machine

Thought I'd include this part since I used VirtualBox VMs in some of the labs in this series. I was having issues copying text from my laptop and then pasting them onto the terminal inside the VM (and then vice versa). I've also included some packages that would be helpful. Some setup doesn't come with pre-built packages like vim.

Custom Partitioning

This follows the same steps as the previous lab but this time we'll be configuring a custom partitioning. Follow the steps in Lab 1 (under "RHEL on VirtualBox" section) up to Step 9: Confirm the Installation Destination. Note that for this lab, we changed our hostname to tst-rhel-local-2.

Data Modelling

Data Modelling and Parent-Child Relationships in Elasticsearch

Exam Objectives

RHCSA exam candidates should be able to accomplish the tasks below without assistance. These have been grouped into several categories.

Firewalld

Firewalld is a Linux management tool that provides a simpler alternative to the low-level and complex nftables, which replaced iptables in modern Linux kernels. It offers an easier way to manage firewall rules and configurations on Linux systems.

Format of `/etc/passwd`

The /etc/passwd file stores user account information. Each line in this file represents a single user and contains seven fields separated by colons (

IPTables

Iptables is a command-line firewall utility that uses policy chains to allow or block traffic. When a connection tries to establish itself on your system, iptables looks for a rule in its list to match it to. If it doesn’t find one, it resorts to the default action.

Killing a Defunct Process

Encountered this when I was trying to install htop on one of my test-RHEL EC2 instances. I was following the steps in this link..

Linux Kernel

The Linux kernel is the core of the Linux operating system, acting as a bridge between the hardware and software. It interacts with hardware devices through drivers, known as modules, which are essential for the system's functionality.

N-grams

Indexing with N-grams in Elasticsearch

Partitions

Managing disk partitions is a critical task for organizing and utilizing storage effectively. Tools like parted, gparted, and fdisk are commonly used for partitioning disks.

Persistent Mounts

Before we go to mounting the disks persistently, we need to know about these two things:

Practice Test 01

These labs are based on Sander Van Vugt's O'Reailly course, "Red Hat Certified System Administrator (RHCSA), 3/e"

Practice Test 02

These labs are based on Sander Van Vugt's O'Reailly course, "Red Hat Certified System Administrator (RHCSA), 3/e"

Practice Test 05

These are some of the scenarios that I haven't tried to simulate yet.

PromQL

Prometheus Query Language

Resizing LVMs

Resizing Logical Volume Management (LVM) allows you to increase the storage capacity of your logical volumes as needed. This is particularly useful when you start running out of space on your disks.

Security Updates

To check for high-priority, security updates, run the command below.

Setting up a Repository

Decided to come back to this again after I installed VirtualBox again on my personal laptop, downloaded the RHEL 8 iso file from developer.redhat.com site and run a VM. I also remember the reason why i stop using VirtualBox. My laptop had a 4gb ram back then and launching VMs quickly make my laptop laggy.

Setting up WebMin Repository

In this lab, we'll set up the Webmin YUM repository on your system. Webmin is a web-based interface for system administration for Unix. Using any modern web browser, you can set up user accounts, Apache, DNS, file sharing, and much more. By setting up the YUM repository, you can easily install and update Webmin through your package manager.

SSH-Based Logins

SSH key-based login is a method to securely connect to remote systems without using a password. Instead, it uses a pair of cryptographic keys: a private key, kept on your local machine, and a public key, placed on the remote server. This enhances security by eliminating the need for password-based authentication.

Using Essential Tools

For the this lab and the succeeding labs, we'll be using our RHEL 8 launched on Amazon EC2 instances. Feel free to do this lab in VirtualBox as well.