[TUHS] End of an era: the last ATC (USENIX Annual Technical Conference)

[Bakul Shah via TUHS]

On Jul 18, 2025, at 4:59 PM, Larry McVoy <lm at mcvoy.com> wrote:
> 
> I sort of get "." to repeat the undo but does nvi have a way to redo the
> changes you originally did?  I've used that to try and track down what
> change I did that caused things to break, being able to go back and forth
> is useful in a long debugging session.

Let us say you want do undo last 4 changes. You type u...
Now you want to redo 3 of them. You type u..

Basically the second u undoes the undo, and . means repeat!
IIRC, in vi you could only undo one change. To redo you
use u again. vim broke that. nvi extended it compatibly.

[This may be a Europe/USA thing. In US a "toggle" button
 seems quite acceptable but perhaps the EU bought into "human
 factors design" which says to *not* use the same control for
 /opposite/ functions as it can likely increase confusion.
 Note: I may be completely wrong here but this was my guess!]