The playground allows you to learn about systemd interactively, right from your browser! Create examples without the danger of breaking your system, and without being distracted by hundreds of unrelated unit files.

Hello!

I recently released a new version of my CLI text processing with GNU sed ebook. This book heavily leans on examples to present features one by one and there are plenty of exercises to help test your understanding of this tool. In addition to sed commands and options, regular expressions are also discussed in detail.

Links:

• Web version: https://learnbyexample.github.io/learn_gnused/ (always free)
• PDF/EPUB: https://learnbyexample.gumroad.com/l/gnu_sed (free for a few days)
• Markdown source, example files, etc: https://github.com/learnbyexample/learn_gnused
• Interactive TUI app for exercises: https://github.com/learnbyexample/TUI-apps/blob/main/SedExercises

I would highly appreciate it if you'd let me know how you felt about this book. It could be anything from a simple thank you, pointing out a typo, mistakes in code snippets, which aspects of the book worked for you (or didn't!) and so on. Reader feedback is essential and especially so for self-published authors.

Happy learning :)

An explaination of how to implement practical procedural macros in the Rust programming language. Explains the different types of macros, then shows an implementation of a procedural macro following best practices, focusing on testing and ergonomics. Assumes some familiarity with Rust.

If we focus on the most-important critical fundamentals, we should be able to become comfortable with the command line in a remarkably short amount of time.

That's what this blog post is all about. It's the missing manual of terminal fundamentals needed to work with modern JS frameworks like React, so you can move onto the fun stuff: building user interfaces!

Most people think assembly is only to be used to write toy programs for learning purposes, or to write a highly optimized version of a specific function inside a codebase written in a high-level language.

Well, what if we wrote a whole program in assembly that opens a GUI window? It will be the hello world of the GUI world, but that still counts.

This is text version of PyCon 2023 tutorial. Video can be found at: https://www.youtube.com/watch?v=5TdIxxBPUSI

SSH is yet another example of an ancient technology that is still in wide use today. It may very well be that learning a couple of SSH tricks is more profitable in the long run than mastering a dozen Cloud Native tools destined to become deprecated next quarter.

One of my favorite parts of this technology is SSH Tunnels. With nothing but standard tools and often using just a single command, you can achieve the following:

• Access internal VPC endpoints through a public-facing EC2 instance.
• Open a port from the localhost of a development VM in the host's browser.
• Expose any local server from a home/private network to the outside world.

And more 😍

This is the first post in a three part series. Check out part 2 and part 3 when you are ready.

It is a beautiful day outside, so let's make a compiler. You don't need any knowledge of how compilers work to follow along. We are going to use Python to implement our own programming language, Teeny Tiny, that will compile to C code. It will take about 500 lines of code and provide the initial infrastructure needed to customize and extend the compiler into your own billion dollar production-ready compiler.

This tutorial is a series of posts that go step by step in building a working compiler. All of the source code can be found in the GitHub repo. If you follow along with all the posts, I guesstimate that it will take you only a few hours.

The Teeny Tiny language we are going to implement is a dialect of BASIC. The syntax is clean and simple. If you prefer a C-like syntax then it will be trivial to modify the compiler at the end.

Fluency on the command line is a skill often neglected or considered arcane, but it improves your flexibility and productivity as an engineer in both obvious and subtle ways. This is a selection of notes and tips on using the command-line that we've found useful when working on Linux. Some tips are elementary, and some are fairly specific, sophisticated, or obscure. This page is not long, but if you can use and recall all the items here, you know a lot.

As a programmer, you use hash functions every day. They're used in databases to optimise queries, they're used in data structures to make things faster, they're used in security to keep data safe. Almost every interaction you have with technology will involve hash functions in one way or another.

Hash functions are foundational, and they are everywhere.

But what is a hash function, and how do they work?

In this post, we're going to demystify hash functions. We're going to start by looking at a simple hash function, then we're going to learn how to test if a hash function is good or not, and then we're going to look at a real-world use of hash functions: the hash map.