How I Passed RHCSA on RHEL 10: Practical Lessons and Preparation Tips
This article is for anyone preparing for the Red Hat Certified System Administrator (RHCSA) exam.
Software Design · System Design · Architecture
Exploring software.
Sharing what I learn.
I’m Shreyas Joshi. This is my personal notebook on software design, system design, and software architecture—a place to collect project notes, useful ideas, and lessons along the way.
The notebook
Ideas from the work
JavaScript Built-in Objects and APIs
This article introduces JavaScript timers and selected built-in APIs for numbers, strings,dates, and regular expressions.
JavaScript Functions, Closures, and Error Handling
This article introduces JavaScript exceptions, closures, immediately invoked functionexpressions (IIFEs), and selected function properties.
JavaScript Objects, Prototypes, and Functions
JavaScript objects are accessed through references. This article introduces objectcreation, property access, prototypes, constructors, and function methods.
JavaScript Arrays and Common Methods
JavaScript arrays are objects accessed through references. Their elements can be changed,and many array methods mutate the original array while others return a new one.
JavaScript Values, References, and Scope
When you assign a primitive value, the variable receives that value. JavaScriptprimitives include strings, numbers, booleans, null, undefined, symbols, and bigints.
JavaScript Switch Statements and Loops
This article is all about basic javascript features like switch and looping. This is in continuation to the basic javascript conditional structs.
JavaScript Fundamentals Compared with C++
This article compares selected JavaScript and C++ fundamentals. The languages share somesyntax, but differ in their type systems, runtime behavior, and memory models.
JavaScript Conditionals and Comparison with C/C++
This article introduces JavaScript objects, functions, strict mode, truthiness, andconditional statements, with comparisons to C and C++.
AWS Storage Types: S3, EFS, EBS, and Snowball
This article introduces several AWS storage and data-transfer services. Product names,classes, and availability can change; consult current AWS documentation before choosinga service.
AWS Block Storage vs. Object Storage
This article compares block storage and object storage at a high level. The examples arehistorical; check current service documentation before making an architectural decision.
The AWS Well-Architected Framework and Elasticity
This article describes the original AWS Well-Architected Framework pillars as they werepresented when this post was written, and introduces elasticity. AWS has since updatedthe framework;...
Docker Images and Dockerfiles: An Introduction
This historical introduction explains Docker image layers and a simple Nginx image. TheUbuntu and Nginx versions shown are obsolete; use maintained base images and currentpackage versions...
Understanding AWS Accounts and Regions
This article introduces AWS accounts, Regions, Availability Zones, and edge locations.
Docker Swarm, Backups, and Container Isolation
This historical walkthrough introduces Docker Swarm and Linux container isolation.Commands and recovery procedures are version- and environment-specific; verify them in atest environment ...
Managing Docker Versions and Logging Drivers
This historical Ubuntu walkthrough covers Docker package versions and logging drivers.Package versions, repository configuration, and supported drivers depend on the DockerEngine and Ubun...
AWS Architecture Terminology
This glossary introduces common concepts used when discussing cloud architecture anddisaster recovery.
Installing Docker Engine on Ubuntu
This historical guide records an installation of Docker Engine on Ubuntu Bionic. Thecommands, repository-key instructions, and package versions below are obsolete; followthe current Docke...
An Introduction to AWS Service Models
This article introduces cloud service models and the AWS shared responsibility model.
Adding Packages to a Yocto Image
This short, historical note shows how I added packages to a Yocto image. Recipe names and override syntax vary by Yocto release; this example is from the Warrior-era setup.For e.g, I woul...
Reading and Writing QSPI Flash with U-Boot on Zynq
This historical walkthrough records how I loaded a kernel and device tree from an SD card, wrote them to QSPI NOR flash with U-Boot, read them back for verification, and booted the kernel...
Byte Order (Endianness): Big-Endian vs Little-Endian
Endianness describes the order in which the bytes of a multi-byte value are stored in memory. It does not change the value itself; it describes how that value is represented across byte a...
Debugging Linux Device Tree Overlays on MicroZed
This historical walkthrough records how I debugged a device tree overlay for an out-of-tree PHY driver on a Yocto-built MicroZed system. Kernel, compiler, and board details affect the exa...
Booting a MicroZed Linux Root Filesystem over NFS
This walkthrough records an NFS-root setup for an Avnet MicroZed Zynq board and an Ubuntu 18.04 development VM. It is specific to that older environment and is not a current production re...
Submitting My First Linux Kernel Patch
This is all about my journey to submit my first kernel patch. Here I have discussed all the important things you must know before you submit your kernel patch and also respond to the feed...
Linux and Windows Utilities: Practical Notes, Part 1
This article collects short answers to common Linux and Windows questions. The examples reflect the tools available when these notes were written; check local versions and options before ...
Setting Up Visual Studio Code for JavaScript
This historical guide records a Visual Studio Code setup on Ubuntu 18.04. VS Code,Node.js, and extensions change over time; check the current documentation and review anextension’s publis...
Bringing Up Avnet MicroZed Linux with Yocto
This historical walkthrough records the steps I used to build U-Boot, a Linux kernel, a device tree, and a root filesystem for an Avnet MicroZed Zynq-7010 board using Yocto Warrior.Also, ...
The Chain of Responsibility Pattern in C++
The Chain of Responsibility pattern lets a request pass through a sequence of handlers. A handler can process the request or pass it to the next handler, reducing the sender’s dependency ...
The Builder Pattern in C++
The Builder pattern separates the construction of a complex object from its representation. This article uses tuner configurations to illustrate a classic builder and director arrangement.
The Observer Pattern in C++ and Qt
The Observer pattern lets a subject notify interested observers when its state changes. A subject can add or remove observers at runtime; the observers depend on the subject’s notificatio...
SOLID Principles: A Practical Guide to Object-Oriented Design
This article introduces the SOLID design principles and some of the trade-offs behind applying them.
Relationships Between Classes: Inheritance, Association and Composition
Class relationships are a foundation of object-oriented design. Two useful questions are whether one type can substitute for another (“is-a”) and whether an object collaborates with or ow...
Calling JavaScript from C++ with Qt WebKit
This article discusses on how to call a JavaScript function from C++ usingQt Framework. This framework uses Qt-Webkit. Currently, there are two waysto achieve this.
Before this notebook
Earlier projects & notes
Some older resources from my previous site are still available in their original form.