mount hides underlying files

[Jerry McAllister]

> 
> Chris Hill wrote:
> > On Thu, 11 Nov 2004, Jay O'Brien wrote:
> > 
> > 
> >>If I mkdir /test and then place files in /test, those files
> >>are no longer visible when I use /test as a mount point. The
> >>files become visible again when I unmount the device.
> >>
> >>I have read documentation explaining this phenomenon, and I
> >>would like to review that documentation again. Is it in the
> >>handbook?
> > 
> > 
> > Yes. There is a discussion of this at
> > 
> > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/disk-organization.html
> > 
> > Also see the following page.
> > 
> 
> Chris,
> 
> Thank you, that answers the basic question, with the word "replaces". 
> That is, when a filesystem is "mounted" to a directory, it "replaces" 
> what was there, it doesn't add to it. This is different from my 
> experience with other operating systems, and was confusing to me.
> 
> I do remember seeing a more verbose description, however, that 
> discusses what happens to the underlying files when something is 
> mounted over the top of their directory; I also vaguely remember 
> something suggesting that this is a way to "hide" files from the 
> casual observer, revealing the files by unmounting the file system 
> that caused them to be hidden. I don't have a reason to hide files; 
> I remember reading the discussions, and would like to read them
> again.

I think that was in one of the online publications such as an OnLamp
article or another of the online magazines..   But, sorry, I don't 
currently have a reference.

////jerry

> 
> Jay O'Brien
>