How to run shell commands on file without saving?

Question

For example, if I want to run tidy on a file

r! tidy %

But I have to save the file beforehand. Is there any way around this?

Answer 1

:range! command

This will run an external command, pipe the lines specified in range to it and replace range with the output of the command.

As a special case, % as a range includes all lines in the buffer. (see help :%) So this should do what you want:

:%! tidy