os-tutorial/00-environment

I'm working on a Mac, though Linux is better because it will have all the standard tools already available for you.

On a mac, install Homebrew and then brew install qemu nasm

Don't use the Xcode developer tools nasm if you have them installed, they won't work for the most cases. Always use /usr/local/bin/nasm

Furthermore, on a mac, qemu is split into multiple binaries. You will want to call qemu-system-x86_84 binfile