Writing an operating system kernel from scratch

I will never not find this kind of project incredibly impressive. It’s interesting to think that Linux, after all, is really just the kernel — and yet getting that work done paved the way to getting an open source version of Unix installed on billions of machines. Great stuff!

It is equally valid to say that Stallman's starting to write a C compiler and Unix utilities (in 1984 whereas the Linux project started in late 1991) paved the way to getting an open source version of Unix installed on billions of machines.

> [Stallman/GNU] getting an open source version of Unix installed on billions of machines.

Agreed, funnily enough GNU tools/compilers also ended up getting installed on a lot of proprietary UNIXes because proprietary UNIX was mostly shit (in user space!). At least most of the ones I had the misfortune to have to work on.

I first came across GNU tools on NeXTSTEP, which wasn't too bad.

If Stallman had started with a kernel, there would be very few people who had the legal right to run any utilities or apps on the new kernel whereas GNU's utilities and apps (e.g., Emacs) were immediately useful (i.e., without breaking any copyright law or violating any software license) to a large population, namely, anyone with an account on a proprietary Unix system, which explains why Stallman chose to start with the userland.