On vacation, with just an iPad keyboard, so I apologize for not doing more digging. As I noted, when taking the blame for the Great Echo Schism, my early exposure to a hp2640 terminal that allowed “rentry” of a previous command was partly to blame. It also led me to use a PS1 ending in @, the default line-kill. When I reentered a command, the @ wiped out the prompt stuff, and only the command survived.

On Tue, Aug 7, 2018 at 10:15 AM Brian Zick <brian@zick.io> wrote:

> > rc uses ;
>
> Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
> default value of $prompt. At least that's how it's described in the
> manual.

In NetBSD 7 the default is ';', but I don't see any reference to a default $prompt in the manual on that system. I wonder if this was a change unique to Berkeley.

B