At the end, in redirection, <<: that’s not how here-documents work. The example gives the impression it will read the given file up until “STOP”, but in reality the shell expects you to keep writing your here-doc until you write “STOP” and then feeds it to the program as if it were all on stdin. I don’t think wc even does anything with the stdin if you give it a filename… Note that variable expansion will happen in here-docs, so it’s a bit different than a simple cat. Also look into here-strings. And process substitution, I find that quite handy.