How to manually trigger fsync()?

I've used libeatmydata to quickly perform apt-get update. Now I want to run standard fsync to make sure that everything is written to disk. How can I do it? Preferably a small script / binary, and for bonus points fsync for real even when libeatmydata is pre-loaded

2 Answers

Calling sync should do the trick.

You can also press Alt+SysRq+S.