In 1981 I was a grad student at CMU, which was running 4.1 or 4.2 at the time. I had spent the previous three years at IBM Research where someone had built some editing stuff into the command line machinery for CMS.

I implemented some input line editing stuff both for the Perq and as a module for the one of the UNIX shells and shared them with some of the systems folks at CMU. I do not know if they were adopted from my implementations ... I am inclined to think not ... there was significant skepticism of the value of command line editing among some of the systems folks.

But the idea of retrieving previous command lines and editing the command line was emerging as a thing in the early 1980s.

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On Mon, Apr 8, 2024 at 11:03 AM Dan Cross <crossd@gmail.com> wrote:

I wonder if anyone can shed any light on the timing and rationale for
the introduction of “word erase” functionality to the kernel terminal
driver. My surface skim earlier leads me to believe it came to Unix
with 4BSD, but it was not reincorporated into 8th Edition or later,
nor did it make it to Plan 9 (which did incorporate ^U for the "line
kill" command). TOPS-20 supports it via the familiar ^W, but I'm not
sure about other PDP-10 OSes (Lars?). Multics does not support it.
VMS does not support it.

What was the proximal inspiration? The early terminal drivers seem to
use the Multics command editing suite (`#` for erase/backspace, `@`
for line kill), though at some point that changed, one presumes as
TTYs fell out of favor and display terminals came to the fore.

- Dan C.