Algol 68C and Unix
Stephen Bourne subsequently reused ALGOL 68's revered if ~ then ~ else ~ fi, case ~ in ~ out ~ esac and for ~ while ~ do ~ od clauses in the common Unix Bourne shell, but with in's syntax changed, out removed, and od replaced with done (to avoid conflict with the od utility).
After Cambridge, Bourne spent nine years at Bell Labs with the Seventh Edition Unix team. As well as developing the Bourne shell, he ported ALGOL 68C to Unix on the DEC PDP-11-45 and included a special option in his Unix debugger "adb" to obtain a stack backtrace for programs written in ALGOL68C. Here is an extract from the Unix 7th edition adb manual pages:
NAME adb - debugger SYNOPSIS adb ] COMMANDS $modifier Miscellaneous commands. The available modifiers are: a ALGOL 68 stack backtrace. If address is given then it is taken to be the address of the current frame (instead of r4). If count is given then only the first count frames are printed.Read more about this topic: ALGOL 68C