DEV Community: Hyeokmin Lee

CalHub - No sign-up, free website for calculation & conversion!

Hyeokmin Lee — Thu, 26 Feb 2026 06:57:12 +0000

How's it going folks!
I built a completely free, no sign-up website for calculation & conversion covering everything from common everyday conversions to specialized engineering and scientific units:

Common Converters: Length, weight, temperature, volume, area, time, and more
Currency Converter: Live exchange rates for 160+ world currencies
Engineering Units: Acceleration, torque, density, angular velocity, and specialized measurements
Scientific Converters: Heat, fluids, light, electricity, magnetism, and radiology units
Health Calculators: BMI and BMR calculators
Duration Calculator: Calculate time between dates

Please check it out at: https://calculate-convert.netlify.app/

If you want me to add any other feature please let me know via Contact Page within the URL.

Super Detailed UNIX/Linux Cheat Sheet!

Hyeokmin Lee — Sun, 22 Feb 2026 06:10:36 +0000

UNIX / Linux Commands — Comprehensive Quick Reference

The first time I opened a terminal and typed ls, I felt completely lost. The second time I tried to delete a folder, I accidentally used rm -rf in the wrong directory. The third time I tried to search a file, I couldn't remember if it was grep or find or something else entirely.

Sound familiar?

The terminal is one of the most powerful tools in computing — and one of the most intimidating to learn, because every resource either over-simplifies it ("just type cd to change directory!") or throws you straight into man pages written for people who already know what they're doing.

This reference sheet sits in the middle: detailed enough to actually teach you, compact enough to keep open while you work.

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🔍 WHAT MAKES THIS DIFFERENT

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Most cheat sheets tell you what a command does. This one shows you:

• What the command looks like when you run it (real terminal output, not pseudocode)

• What each flag actually means — not just the abbreviation, but the full behaviour and when it matters

• The differences that trip people up: cd .. vs cd -, > vs >>, rm vs rm -r vs rm -rf, cp vs cp -r

• The patterns professionals use daily: piping, redirection, background jobs, process management

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📋 WHAT'S INCLUDED

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200+ commands across 10 sections — File System, Viewing & Editing, Searching, Redirection & Pipes, Permissions, Process Management, Networking, Compression, System Info, and Package Management — plus a full keyboard shortcuts and operators section.

Every command entry includes:

→ The exact command syntax

→ Available flags and variants

→ A description and a live terminal example with realistic output

Plus a dedicated Flag Reference table beneath — 95 rows of full-prose explanations for every flag in the document. Finally understanding why chmod 755 vs 644 vs 600 matters. Finally knowing the difference between kill and kill -9.

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👤 PERFECT FOR

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✅ Students working on remote university Linux servers

✅ ML/AI engineers SSHing into GPU machines to run training jobs

✅ Developers new to Linux or moving from a GUI-only workflow

✅ Anyone who keeps a browser tab open to Stack Overflow for basic commands

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Now available both in .docx and .pdf at https://tux1991.gumroad.com/l/LINUX!
Buy it once. Refer to it forever.

A Complete Python Beginner Guide!

Hyeokmin Lee — Sun, 22 Feb 2026 06:07:13 +0000

Hello there!

I wrote a Python handbook called "Python for the Utterly Uninitiated" for complete beginners. It is compact, detailed, and everything in one place.

I wanted to make something that doesn't waste your time. Each chapter covers exactly what it needs to cover, nothing more — but it doesn't skip the parts that actually matter either.

The way it's structured: every concept gets a code example, and every code example gets a plain-English walkthrough underneath it explaining what each line did and why. No assumed knowledge, no hand-waving.

Here's what's covered across the three volumes:

Vol. 1 — Installation and environment setup, variables, numbers, strings, booleans, conditionals, and loops. The foundations, done properly.

Vol. 2 — Debugging, lists, tuples, dictionaries, sets, type conversion, and functions in depth. The stuff that trips most beginners up.

Vol. 3 — File I/O, exception handling, Python's standard and third-party libraries, object-oriented programming from scratch, and three full practice projects.

Each chapter ends with practice challenges so you can actually test what you just read — not just passively absorb it. There, of course, are solutions as well at the very end of each handbook.

You can grab each volume separately or get the full bundle, which works out cheaper than buying all three individually. Thanks for reading!

Vol. 1 (Chapters 0–7): tux1991.gumroad.com/l/PUUv1
Vol. 2 (Chapters 8–14): tux1991.gumroad.com/l/PUUv2
Vol. 3 (Chapters 15–21): tux1991.gumroad.com/l/PUUv3
Full bundle (best value): tux1991.gumroad.com/l/PUUf

Tux