I’m not sure if you watched the video or read its description, but pipes are the focus of this implementation. He describes pipes as “the core of the UNIX shell

I’m not sure if you watched the video or read its description, but pipes are the focus of this implementation. He describes pipes as “the core of the UNIX shell” in the video. I suppose that is somewhat up for debate, but building complex tasks out of composable pieces is certainly up there among UNIX’s design goals, and pipes are a big part of that. OTOH, his implementation does not seem to cover output redirection à la `exec` (file-based, file-descriptor-based, or named-pipe).