Microsoft HoloLens Developer???s Guide

Command-line interface

In CLI, users had to learn the language of the application. Using the system consisted of typing in all sorts of commands, usually without any help from the system. Since computing power was limited, most commands were abbreviated and used flags and options as well. A proficient user would have to memorize all these options. It would be quite common for users to have the manual of the system lying next to the keyboard, more often than not spanning hundreds of pages.

This is still in use today. Most system administrators prefer to use command line-based systems since that gives them much more power. An example of such a command is this:

Dir | Rename-Item -NewName { $_.name -replace " ", "_" }

This weird looking line ...