Huh? The Bourne shell was done in the late V6 era, and was included in the release, starting with V7. The classic shell (the Thompson shell, originally) was included starting with V1: http://squoze.net/UNIX/v1man/man1/sh That one was written in PDP-11 assembler: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1/sh.s but by V5 it had been re-written in C: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/source/s2/sh.c Mind, I'm not saying that your theory as to what the code being enquired about does is wrong; but the theory that 'this is what the shell was before the Bourne shell' does seem to be off base. Noel