Way back in the 1960s — 70s, computers were becoming more than just  calculators. They could save files to disk and have multiple running  applications with multiple users. But these things were difficult to  control and easy to break. Thankfully, there was a very smart idea to  cover all these internal bits in a nice, usable shell.

Read more : medium.freecodecamp.org/the-command-line-1fdbc692b3bf