On Wed, Mar 23, 2016 at 6:06 PM, Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:
  

It was in V6, and probably before that; it's truly ancient.

 
​Yep - you see vestiges in ​
v0 - Dennis used an rc file call the parts of the B compiler.    In V1's man page, it's listed as a bug that
​ calling the B compiler via that script 
should probably be a command.
​  Having exec call the shell if the file is executable and not a 4xx magic number has not yet appeared, but its not that far off.

Clem​