Easiest way to execute local file from Firefox?

Question

I am developing a web application. I would like to extend my error messages (and their backtraces) so that I can click on the mentioned file, and have it opened automaticall

Answer 1

http://mozex.mozdev.org/

MozEX is an extension which allows the user to use external programs for these actions:

* edit content of textareas (possibly utilizing a spell-checker, color syntax etc.)
* view page source
* handle mailto, news, telnet and FTP links
* download files
* ... and many more :)

The universal handler lets you enter a list of protocol schemes, e.g., "abc://,def://" and a command to handle them. So you just have your application generate a url that begins with your chosen (made up) protocol, and mozex will intercept a click on the url and send the url to your chosen command as a paramater.

I think this is exactly what you want.