Among the reactions to my entry on how ed(1) is no longer a good editor today was people wondering out loud if ed was ever a good editor. My answer is that yes, ed is and was good editor in the right situations, and I intend to write an entry about that. But before I write about why ed is a good editor, I need to write about why you should be willing to believe that it is. To put it simply, why you should believe that ed is a good editor has nothing to do with anything about its technical merits and everything to do with its history.

Ed was created and nurtured by the same core Bell Labs people who created Unix, people like Dennis Ritchie and Ken Thompson. Ed wasn't their first editor; instead, it was the end product of a whole series of iterations of the same fundamental idea, created in the computing environment of the late 1960s and early to mid 1970s. The Bell Labs Unix people behind ed were smart, knew what they were doing, had done this many times before, had good taste, were picky about their tools, used ed a great deal themselves, and were not afraid to completely redo Unix programs that they felt were not up to what they should be (the Unix shell was completely redesigned from the ground up between V6 and V7, for example). And what these people produced and used was ed, not anything else, even though it's clear that they could have had something else if they'd wanted it and they certainly knew that other options were possible. Ed is clearly not the product of limited knowledge, imagination, skill, taste, or indifference to how good the program was.

It's certainly possible to believe that the Bell Labs Research Unix people had no taste in general, if you dislike Unix as a whole; in that case, ed is one more brick in the wall. But if you like Unix and think that V7 Unix is well designed and full of good work, it seems a bit of a stretch to believe that all of the Bell Labs people were so uniquely blinded that they made a great Unix but a bad editor, one that they didn't recognize as such even though they used it to write the entire system.

Nor do I think that resource constraints are a convincing explanation. While the very limited hardware of the very earliest Unix machines might have forced early versions of ed to be more limited than prior editors like QED, by the time of V7, Bell Labs was running Unix on reasonably good hardware for the time.

The conclusion is inescapable. The people at Bell Labs who created Unix found ed to be a good editor. Since they got so much else right and saw so many things so clearly, perhaps we should consider that ed itself has merits that we don't see today, or don't see as acutely as they did back then.