FWIW, in Tanenbaum's original paper (which the author is reading), the correct meaning of the example is given quite plainly: "consider a simple UNIX pipeline:

FWIW, in Tanenbaum's original paper (which the author is reading), the correct meaning of the example is given quite plainly: "consider a simple UNIX pipeline: sort <infile | uniq | wc -l >outfile that sorts infile, an ASCII file with one word per line, strips out the duplicates, and prints the word count on outfile." So yes, it does seem the author did missed at least that part. Not sure about the rest of their arguments, but at this point, I'd say it's easy enough to find the original paper, which does seem quite readable. https://www.cs.vu.nl/~ast/Publications/Papers/euteco-1988.pdf https://www.cs.vu.nl/~ast/Publications/Papers/euteco-1988.pd...