This article is based on my of the same title. Originally published at on May 4, 2020. PyCon 2020 talk vinayak.io . Well, not quite the command line we know today. In the beginning, was the command line We had typewriters. We were communicating using Morse code. One fine day, someone had an idea to connect a typewriter to an existing network of communication wires. And the teletypewriter was born! Image: Teletype teleprinters in use during World War II, Source: Wikipedia Teletypes removed the need for a human to know Morse code, which improved message typing speed and delivery time. In this , the narrator describes how a teletype takes only a matter of seconds to deliver a message from London to Edinburgh. A stark contrast to the earlier ETA of one week — the time taken by a mail coach to undertake the same 600 km journey. 1932 video Image: Assembly of IBM 1401 computers, Source: Computer History Museum Meanwhile, computers were becoming powerful enough to interact with users in real-time. Another fine day, someone had an idea to repurpose a teletype, connect it to a modem, and use it as a remote interface to early computers. This was the origin of the command-line interface! Among these teletypes were the and the . Users typed commands after a prompt character was printed on paper. After they were satisfied with the input, they would press Enter which would then send the command to the computer. And finally the output from the computer would be printed on paper again. Friden Flexowriter Teletype Model 33 Image: The VT100, Source: Wikipedia Teletypes were continued to be used as terminals to computers, until video displays came into the picture during the late 1970s. Video terminals quickly became popular input-output devices for computers after the manufacturers moved to a set of . common standards Today, physical teletypes and video terminals are obsolete. We instead have terminal emulators, which are . But, have modern terminal emulators borrowed any features from the OG metal beasts? software simulations of the real thing The Guide The jargon file. Learn how terminals and CLIs work. Part 1 — Anatomy of a Terminal and CLI Look at packages that can be used to write CLIs, which are available in the Python standard library and on PyPI. Part 2 — Python packages for writing CLIs Explore various CLI use cases and see how Click can be used to implement a clone of git, with some commonly used git subcommands. Part 3 — Writing and packaging a CLI using Click Look at some principles that can create a nice CLI user experience. Part 4 — User Experience Closing Thoughts I hope that you got a lot of touchpoints to the CLI ecosystem which you can now explore further, an understanding of how terminals and CLIs work and how to write CLIs in Python! Stay safe and be well.
