It seems ':pipe' sends the data to stdin, I was trying to see a pdf file and the programs I tried (evince, mupdf) do not seem to support this (or perhaps usage

It seems ':pipe' sends the data to stdin, I was trying to see a pdf file and the programs I tried (evince, mupdf) do not seem to support this (or perhaps usage is different?). Seems like a good patch to implement a command that saves to a temporary file and opens with provided program, will certainly follow development, great work!