how do I tell FreeBSD to sync, for real ?

[Lowell Gilbert]

user <user at dhp.com> writes:

> Sometimes you delete a large batch of files, or you do some other serious
> FS operations and the output of `df` does not tell you immediately of the
> new disk space, etc.
> 
> If you run something like:  sync
> 
> Or even:  sync ; sync
> 
> it still doesn't show up.  You either have to wait for a while, or you
> have to get silly with something like:
> 
> sync ; sync ; sync ; sync ; sync ; sync ; sync
> 
> (or unmount and remount the FS)
> 
> -----
> 
> So my question is, well first off, why does this happen this way ?  But
> mostly what I want to know is, is there a more graceful way to tell
> FreeBSD "sync for real this time, not just for joke only ?"
> 
> Basically, is there a nicer way to get what I want than:
> 
> sync ; sync ; sync ; sync ; sync ; sync ; sync

"sleep 30"?

http://www.usenix.org/publications/library/proceedings/usenix99/full_papers/mckusick/mckusick.pdf