In lighttpd, to disable PDF opening in browser, add following config files in lighttpd.conf. This is useful in increasing CTR as browsers usually get stuck while loading PDF files.
$HTTP["url"] =~ "(.*)\.pdf" { mimetype.assign = (".pdf" =>"application/octet-stream") setenv.add-response-header = ( "Content-Disposition" => "attachment" ) }
Dont forget to enable setenv module, if not already done …
server.modules += ( "mod_setenv" )
service lighttpd reload