As I wrote in another comment, the author seems to use a broader term for systems programming: > Regardless of you a system language programmer, DevOps, perfor

As I wrote in another comment, the author seems to use a broader term for systems programming: > Regardless of you a system language programmer, DevOps, performance engineer or wear other hats, the more you know about the Operating System, the more you can do your job better. Take all prevailing Unix-like Operating Systems as an example, from kernel to command line tools, they are almost implemented in C.