Why are commands two letters?

Every keystroke was a physical clunk. Short commands were a necessity

ls, cd, rm, pwd: the commands you type most often are remarkably short. The usual explanation is the hardware. In the 1970s, when Unix was born, teletype terminals took real physical time to type each character. Every keystroke triggered a mechanical clunk. So, the story goes, frequently used commands were kept short.

ls is "list", cd is "change directory", rm is "remove", pwd is "print working directory". Just the opening letters or consonants of English words, the ultimate abbreviation. This convention of stripping down words was born from the engineers' obsession with saving every single keystroke. And these abbreviations are still in use today, over 50 years later.

Behind every short command lies the pragmatism and elegance of the pioneers who came before us.