Probably we're talking about different kinds of pipes. I'm thinking of the vertical bar pipe, i.e. dir | sort, which is implemented at the command line and requires no application modification. The command dir | sort sends the dir output to sort input and the output is a sorted directory (which in its basic form isn't a lot of use because most dir commands include some sorting options anyway, but if sort implements a type of sort that dir doesn't, then this becomes useful).