Scenario 1… You installed Vagrant with VirtualBox on your local machine and have a sweet nginx setup going as your development environment. You made a few changes to a CSS file and the new style is not reflecting on the page. You try saving the file again in your text editor, no go. You look at the file on the server, it’s cool. You restart the nginx service, still no change. You restart the services for php5-fpm and memcached, maybe even mysql… no go.
Something has captured this file in cache and is not letting go!
Scenario 2… Same setup. You made a few changes to a JS file and the script doesn’t seem to be working. Must be a caching issue. You try saving the file again, look at the file on the server, restart nginx, restart everything. Finally look at the console in your browser and see some kind of random error.
Sooner or later, with one of these files, you open it up and see these:
What the what? It’s an encoding issue? Not a caching issue? Or it’s a… wait, what?
Hopefully you haven’t spent too much time trying to figure this out before stumbling on a site like this one that tells you the only change necessary is a simple line in your nginx config file.
Find the spot in your assorted nginx config files that says ‘sendfile on’ and change it to ‘sendfile off’.
Sendfile is used to ‘copy data between one file descriptor and another‘ and apparently has some real trouble when run in a virtual machine environment, or at least when run through Virtualbox. Turning this config off in nginx causes the static file to be served via a different method and your changes will be reflected immediately and without question – or black question mark diamond thing.
Hope that saves you a minute.
For further reading, consider those that have stumbled on the same problem before.
Or, even better – more detail about sendfile itself and other common nginx pitfalls: