Re: A question

[jlarkin@aij.st.hmc.edu (John T. Larkin)]

> > How does the system handle this scenario:
> > Suppose you have / and /usr on different partitions.
> > Before the system mount the usr partition it creates some files under the 
> > directory /usr, and then mounts the usr partition on /usr. 
> 
> It won't mount! I tried this very same thing like this:
> 
>   I created a ordinary text file under /floppy. I then attempted to mount a
> floppy to that directory and got back.....
> 
> ....
> mount: /dev/fd0 already mounted or /floppy is busy

This is incorrect reasoning.  You can create as many files as you like in
the directory /floppy, and still mount a floppy there.  The reason
why mount reported /floppy as busy is either because a user was currently
in the directory /floppy, or there was a file open in that directory.  

When you mount a filesystem, the files on that filesystem take the place of
whatever files were previously in that directory.  Ie, if /usr is on the
root filesystem, and if you have foo in /usr, and then mount a partition 
on /usr, foo cannot be accessed.  As soon as you umount /usr, you can see
and use foo again.
-- 
				- John Larkin	
				- jlarkin@hmc.edu
				- http://aij.st.hmc.edu/~jlarkin