In the bad old days, when, from memory and comparison with vast improvements in the later editions of K&R's chapter on pointers etc., the Lions' Commentary on U

In the bad old days, when, from memory and comparison with vast improvements in the later editions of K&R's chapter on pointers etc., the Lions' Commentary on UNIX 6th Edition, with Source Code (https://en.wikipedia.org/wiki/Lions%27_Commentary_on_UNIX_6th_Edition,_with_Source_Code https://en.wikipedia.org/wiki/Lions%27_Commentary_on_UNIX_6t...) was held by many in equal or greater esteem than K&R. The code has bee implemented as xc6 (https://en.wikipedia.org/wiki/Xv6 https://en.wikipedia.org/wiki/Xv6), but I haven't looked at it.