One Argument with a cat Isn't Enough

What's wrong with this command line?

cat 

% cat filename | tr -d '\015' > newfile

As Tom Christiansen wrote in a Usenet article:

A wise man once said: if you find yourself calling cat with just one argument, then you're probably doing something you shouldn't.

That command line only uses cat to feed the file to the standard input of tr. It's a lot more efficient to have the shell do the redirection for you with its < character ():

% tr -d '\015' < filename > newfile

- JP, TC