ultimate-vim/sources_non_forked/nginx.vim/ftdetect/nginx.vim

au BufRead,BufNewFile *.nginx set ft=nginx
au BufRead,BufNewFile nginx*.conf set ft=nginx
au BufRead,BufNewFile *nginx.conf set ft=nginx
au BufRead,BufNewFile */etc/nginx/* set ft=nginx
au BufRead,BufNewFile */usr/local/nginx/conf/* set ft=nginx