Sorry, I remembered it from AUUGN and checked those first, then searched for "CCMD Unix Columbia.edu" and got the hit on Lar's PDP-10 sources.

and note the dyslexic spelling in my earlier email of AUUGN -- sigh.

On Sat, Jul 31, 2021 at 12:06 PM Richard Salz <rich.salz@gmail.com> wrote:

You gave it away :) Half the fun is getting the search right.

The old kermit program from Columbia has an implementation in portable (for its time) C.

On Sat, Jul 31, 2021 at 12:03 PM Clem Cole <clemc@ccc.com> wrote:
https://github.com/PDP-10/sri-nic/blob/master/files/fs/c/ccmd/ccmdmd.unx

On Sat, Jul 31, 2021 at 11:46 AM Richard Salz <rich.salz@gmail.com> wrote:
Look for "comnd jsys" that exact spelling. Source code is around.