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.

I agree - there's a number of kernels that were "open source" and released at a similar time enough time to linux (e.g. 386BSD in '92) that I could see any of those winning the "community battle" and taking that space instead, but no real credible "development toolchain" equivalent until decades later.

Though I'm unsure how differing licenses might have affected this - I suspect that really early in it's development the "copyleft" nature of the GPL Linux didn't make as much of a difference, as from what I remember most commercial uses of Linux didn't come until it had already gained significant momentum.