The original bourne shell source was using mac.h ( https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/sh/mac.h https://minnie.tuhs.org/cgi-bin/utree.p

The original bourne shell source was using mac.h ( https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/sh/mac.h https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd... ), a bunch of macros, according to wikipedia, "to give the C source code an ALGOL 68 flavor." Here's the original source tree, if you're interested: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/sh https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd...