mount hides underlying files
Jay O'Brien
jayobrien at att.net
Fri Nov 12 16:32:20 GMT 2004
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.
Jay O'Brien
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