Here's what I want to do. I would like Nautilus to associate HTML files with Firefox. So I go to "Hat Menu" -> Preferences -> File types and programs -> Documents -> World Wide Web -> HTML page I then click on Custom & add the following line : ~/programfiles/firefox/firefox -remote 'openURL (%s, new-window)' I would like %s to be replaced by the path & filename of the file that I've double-clicked on. If I leave it as is for the moment, Firefox opens up but loads www.hoovers.com instead. PS. I use the remote parameter, because if I happen to have an instance of Firefox allready running, when I double click on an HTML file, I get a Profile Dialog box because Firefox cannot have two instances using the same profile ( unless someone can show me how ).