A Deep Dive into the ed Text Editor

There's a long-running joke, a shibboleth tossed at new users, that " ed is the standard editor ". This is often said with a wry smile, as ed is notoriously user-unfriendly. Its default state is a blank line, it offers no prompt, and its only error message is a single, cryptic ?. But the secret, and the reason the joke has such staying power, is that it's fundamentally true. For early Unix, ed was…