Currently working on a Stripe integration where I had the same need.

I've also found the following iteration quite useful to make sure you are sending back the right headers.

[code]curl -X POST http://localhost/app/test.php --data @data.txt -D- -o/dev/null -s['code]

-D- will output the headers
-o/dev/null will omit the returned body
-s will not show the progress bar