Architecting an Ultra-Minimal Linux VM with Buildroot | Part 1: Build, Break, Fix

This is Part 1 of a multi-part series. We go from zero to a working VM that passes every audit check. Part 2 will cover packaging it into a bootable ISO and squeezing under the 20MB target. My new semester just started, and one of the first challenges from my OS module was this: "Build the smallest bootable Linux VM you can. It must only pass the tests in this bash-testing-script, nothing more. Personally, I'd love to see <20MB." Sounds simple. It's not. Everything has gotten bigger. Software that would've been lean 15 years ago is now bloated by default. But let's try to ace it anyway. The Audit Script: What We're Actually Building For Before touching a config file, we need to know what success looks like. The professor gave us audit.sh . If it doesn't return all-OK, the VM fails; no matter how small it is . Here's what the script checks: Shell & basic commands command -v sh > /dev/null 2>&1 && ok "POSIX-Shell" for cmd in cp mv cat rm ls ; do command -v " $cmd " > /dev/null 2>&1 && ok