On *nix systems, a user can use the
sync command to force any pending writes in the kernel's disk cache to be flushed to disk. Does Windows have a similar command?
Yes - it's also called Sync, it's part of the SysInternals Suite:
Use it whenever you want to know that modified file data is safely stored on your hard drives. Unfortunately, Sync requires administrative privileges to run. This version also lets you flush removable drives such as ZIP drives.