Re: A Basic Mount Observation
- Date: Tue, 7 May 2019 11:20:57 -0400
- From: Dan Ritter <dsr@xxxxxxxxxxxxxxxx>
- Subject: Re: A Basic Mount Observation
Martin McCormick wrote:
> I may just be remembering things the wrong way but it
> seems like that for most of my memory, one could be root and, if
> you cd'd to a mount point, one could mount /dev/whatever on that
> mount point and immediately see the top of the new tree you had
> just mounted. If you cd'd in to that tree and tried to umount,
> you got the error that the file system was busy which makes sense
> because you are trying to saw off the limb you are sitting on, so
> to speak.
> If you cd'd out of the mount point and nobody else was in
> it, you could umount and all was well.
> I accidentally discovered now that I can become the root
> user, cd to a mount point and mount something with a subsequent
> ls of my current directory yielding nothing new. One doesn't see
> the new mount.
> If you open another session and look at the mount point,
> the new mount is there. You can even create a file under the new
> mount which is only visible to you if you didn't cd out of the
> mount point. Everybody else who looks at that point will see
> what's mounted there and not the test file slipped in under the
> Has this always been the normal behavior of mount or has
> there been a change?
mount /dev/whatever .
This behavior has always been consistent in Linux, as far as I am aware.
The handle to your current directory cannot be changed out from
underneath you; only when you move away from it can it be
released, and from then on you see the new mount.