My OS is Ubuntu 12.04. My firefox is 26.0.
When I try to directly open (instead of save) pdf files downloaded from firefox, I am sometimes asked to open the file in Evince and sometimes in Emacs. For example, the pdf file downloaded from http://www.4shared.com/office/joqIr8Gd/30-days-to-a-more-powerful-voc.htm is opened in Emacs. pdf files downloaded from my Google drive are opened by Evince.
How can I make all pdf files opened in Evince, and not by Emacs?