I doubt there a cli or "hacker" ways of creating a roadmap. For a dead simple roadmap you just need a bullet point list with the items sorted in the order you want to crack them.
I do some personal goals and plans for the year in Evernote, which is to say, not a hacker way at all. But it works and I just need to sync between 2 devices.
Trello, Spreadsheet, and Presentation are another good way to build a roadmap. Again, far from being a hacker way but it works with small teams. In fact, it also works for huge companies. I've seen powerpoint used for building roadmap in a 2K+ person company.
Finally, the least hacker way but probably the most comfortable (when you know exactly what you need) is to use existing tools made for this specifically: