I don't get the anticat crusaders. The overhead of a `cat` command surly is entirely negligible ?

    cat moby-dick.txt | ./words.sh > words.txt

I much more readable to me than

    < moby-dick.txt ./words.sh > words.txt

In the `tr` case I kinda agree, but there is a niceness to the flow when all the transformation steps are aligned like that.

> cat is for concatenating files

The real world disagrees.

It's nice to know that `< file` work though. If the input of an pipeline is what's varying writing it like `{ command1 | command 2 } < input.txt` make it slightly more convenient iterating on since changing the last word is more accessible after getting the command from history. (turning on noclobber to avoid accidentally typing `>` to be safe)