Look familiar? Then you must be old enough to have used DOS, perhaps the best-known command-line-based OS in popular computing history. I’m proud to have done so myself, though a few years later and I would likely have missed out altogether.
The history of the OS is well-documented around the web, and perusing it is a nice reminder of the way things used to be. It came into its own in the early mid eighties (after being bought by Microsoft in 1981), mirroring the rise of the personal PC. Though the many developers that read this blog likely have a more varied personal OS history, DOS is something we can probably all look back on semi-fondly. I have fond memories of booting our 486 into 3.1 and immediately navigating to the \games directory to launch Commander Keen for some 16-color alien-blasting.
The legacy of DOS is still present today. DOS-compatible computing is the reason system drives start at C (A and B were floppies), and why many of our file extensions are the way they are. And I still feel the effects of DOS’s 8-character limita~1 today.
You can see the step-by-step improvement of the OS (by several companies, more like Linux-compatibles today than anything else) at this Wikipedia page, and a more succinct history can be found here.
If you feel like taking the old OS for a spin, try booting up FreeDOS and see if you still have your old directory navigation skills. Or if you just want to escape into the games of yesteryear, pick up DOSBox (and a frontend) and head over to Classic DOS Games or Abandonia.