[nisa]

I guess it is part of the idea that you can ignore that. The shell script is _good enough_ for 80% (I made this up) of use cases. Knuth's solution is probably faster and requires less resources but if I want to reverse the filter order or change something else You are way faster using the shell script. It's also probably not so difficult to look up how each of these tools work internally to make an informed guess on time and space complexity. This will come in handy if you use the tools next time. And unix tools aren't so slow. I wrote some C++ code using mmap() files to filter out some chars. It was only marginally faster than some pipe using tr.

[Niten]

To be more precise, I think the biggest problem with this anecdote is the notion that this guy somehow "one-upped" Knuth by coming up with a pragmatic rather than a theroetically optimal solution. Knuth is a mathematician after all, and if someone asks him to write a program they're implicitly asking for a mathematical result, not an unremarkable engineering tool.

So no, taking this anecdote at face value, this guy didn't "one-up" Knuth; they were effectively answering two different questions. There is more to computer science than finding the simplest shell script to solve the 80% case.