I am starting with a default installation of nginx. The only modification I've made to my enabled-sites/default
file is:
root /home/ubuntu/www
...where I have a web site and a /pdf
folder that contains my pdf files.
If I click a link to a pdf file, it gets served as text/html and of course looks rather broken in the browser window.
If I add Jeremy's configuration section from http://www.jeremywalworth.com/index.php?q=taxonomy/term/49, then I get 404's for the same pdf file link.