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Free tutorials
Practical guides on AWS, serverless backends, AI and the command line, with real code and the same diagrams I use in the courses.
AWS & Serverless
Validate API Gateway requests in Lambda with Zod: a reusable TypeScript wrapper (400 vs 500)
Stop repeating JSON.parse and try/catch in every Lambda. Build a withValidation wrapper that validates body and query with Zod, types your handler automatically and returns the right 400 or 500.
12 Nov 2026 · AWS · Lambda · TypeScript
AWS & Serverless
What belongs outside the Lambda handler? Reuse clients, avoid the shared-state bug
Lambda reuses your code between requests. Learn what runs once per container, which objects to create outside the handler for speed, and the shared-state bug that makes results grow with every call.
12 Nov 2026 · AWS · Lambda · TypeScript
Linux & the Command Line
What is /dev/null? stdin, stdout, stderr and 2>&1 explained
Every Linux command has three streams: stdin, stdout and stderr. Learn to redirect each with >, >>, <, 2> and 2>&1, and what > /dev/null 2>&1 really does in scripts and cron jobs.
12 Nov 2026 · Linux · Bash · Redirection
Linux & the Command Line
What is a shebang? #!/bin/bash vs #!/usr/bin/env bash explained
What the #! line at the top of a script does, how the system picks the interpreter, the difference between /bin/bash and /usr/bin/env bash, shebangs for Python and Node, and the 'bad interpreter' error.
12 Nov 2026 · Linux · Bash · Shell scripting
AI & LLMs
Amazon replaced Claude Sonnet with a tiny decision model: how a decider works and how to try one
How Amazon cut a ticket-labelling bill by 98% by swapping an LLM for a small decision model (Strands Decider). What a decider is, when it fits, how to run one, how to roll it out safely, and a cost calculator.
11 Nov 2026 · AI · LLM · AWS
Linux & the Command Line
Absolute vs relative path in Linux: the Unix filesystem explained
How the Unix filesystem tree works, the difference between absolute and relative paths, and how to move around with pwd, cd and ls, plus the shortcuts /, ~, ., .. and -.
10 Nov 2026 · Linux · Bash · Beginners
AWS & Serverless
AWS CDK tutorial in TypeScript: from CloudFormation to your first stack
Why infrastructure as code beats clicking in the console, how CloudFormation works, what CDK constructs are, and how to bootstrap, synth and deploy a real stack with S3, Lambda, DynamoDB and API Gateway in TypeScript.
10 Nov 2026 · AWS · CDK · CloudFormation
Linux & the Command Line
Customize your shell: .bashrc vs .zshrc, aliases and the PS1 prompt
Why your aliases vanish when you close the terminal, which config file Bash and Zsh read at startup, how to make aliases and environment variables permanent, and how to change your prompt with PS1 or PROMPT.
10 Nov 2026 · Linux · Bash · Zsh
AWS & Serverless
DynamoDB data modeling explained: partition key, sort key and GSI (with diagrams)
How DynamoDB stores data in partitions, what partition keys, sort keys and primary keys are, when to add a global or local secondary index, and how to design a table from access patterns. With a real AWS CDK example.
10 Nov 2026 · AWS · DynamoDB · NoSQL
AWS & Serverless
Full-text search on AWS with OpenSearch, Lambda and CDK (step by step)
Why DynamoDB can't do search, how an inverted index works, OpenSearch clusters, mappings and the Query DSL, multi_match search from a Lambda, and creating the index automatically with a CDK custom resource.
10 Nov 2026 · AWS · OpenSearch · Lambda
Linux & the Command Line
How the shell finds commands: PATH and environment variables explained
What really happens when you type ls: how the shell searches the PATH variable directory by directory, how to use which, why you see 'command not found', and how to add your own folder to PATH.
10 Nov 2026 · Linux · Bash · Zsh
AWS & Serverless
How to build a YouTube-like video streaming backend on AWS (serverless architecture)
A complete serverless architecture for a video platform on AWS: API Gateway, Lambda, S3 presigned uploads, MediaConvert transcoding, EventBridge, DynamoDB and OpenSearch, deployed with CDK. The design behind the VidShare course.
10 Nov 2026 · AWS · Serverless · Architecture
The full course
VidShare: 109 lessons
Build a production-style video streaming backend on AWS, from architecture to final test.
See the course and free lessons →The full course
CLI Mastery: 57 lessons
Get fast and fluent in the terminal, from the filesystem to shell scripts and real servers.
See the course and free lessons →Free download
Linux command line cheat sheet
One printable page: navigation, files, permissions, pipes, processes, scripts and SSH.