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Re: File real location

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On 2011-04-26, notbob <notbob@notbob.invalid> wrote:
> On 2011-04-26, The Natural Philosopher <tnp@invalid.invalid> wrote:
>> Richard Kettlewell wrote:
>>> JimR <NotReallyMyEmail@example.net> writes:
>
>>>> Now I create a file on it, let's call it bar.  Now I have
>>>> /foo/bar
>>>>
>>>> In an alternative case, the filesystem is not mounted.  I can still
>>>> create a file bar in the directory foo, but it will fall onto the
>>>> default filesystem (likely root filesystem).
>>>>
>>>> How can I tell the difference between these 2 files, i.e., on which
>>>> filesystem did the file land?
>>> 
>>> stat() it and look at st_dev.
>>> 
>> I bow to a superior solution...
>
>
> Ummm.... let's back up a bit.  Nevermind I haven't a clue what stat()
> and st_dev are.  If a "filesystem is not mounted", how could there be
> any root (/) dir?  If the dir foo has not been mounted how can one put
> a file into a dir that doesn't exist ...in a filesystem that hasn't
> been mounted?  Is there some editor ....cat, vi, emacs... that will
> create a filesystem and dir if a nonexistent dir/file is specified and
> doesn't exist?

A mountpoint of a filesystem is a directory on another filesystem, often
the so called root filesystem (because it contains the /directory). If
the system is running at all it has a / filesystem already mounted. Now
in the OP case, that contains a directory called /foo. That is just a
regular directory, but on top of that directory (hiding anything which
happens to be already in that directory) can be mounted another
filesystem. Thus, contents of /foo can exist both on the original / filesystem and on
the new mounted filesystem. If the mounted filesystem is actually
mounted, all original contents of /foo on the / filesystem are
inaccessible and hidden, until the new mounted filesystem is unmounted. 


>
> nb --confused

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Thread

File real location JimR <NotReallyMyEmail@example.net> - 2011-04-26 13:06 -0400
  Re: File real location Richard Kettlewell <rjk@greenend.org.uk> - 2011-04-26 18:24 +0100
    Re: File real location The Natural Philosopher <tnp@invalid.invalid> - 2011-04-26 18:28 +0100
      Re: File real location notbob <notbob@notbob.invalid> - 2011-04-26 18:08 +0000
        Re: File real location Richard Kettlewell <rjk@greenend.org.uk> - 2011-04-26 19:14 +0100
        Re: File real location Tim Watts <tw@dionic.net> - 2011-04-26 19:25 +0100
        Re: File real location unruh <unruh@wormhole.physics.ubc.ca> - 2011-04-26 18:43 +0000
        Re: File real location Chris Davies <chris-usenet@roaima.co.uk> - 2011-04-27 16:31 +0100
    Re: File real location Tim Watts <tw@dionic.net> - 2011-04-26 19:08 +0100
    Re: File real location JimR <NotReallyMyEmail@example.net> - 2011-04-26 14:43 -0400
      Re: File real location Richard Kettlewell <rjk@greenend.org.uk> - 2011-04-26 20:28 +0100
        Re: File real location JimR <NotReallyMyEmail@example.net> - 2011-04-26 17:00 -0400
  Re: File real location The Natural Philosopher <tnp@invalid.invalid> - 2011-04-26 18:27 +0100
  Re: File real location "Chris F.A. Johnson" <cfajohnson@gmail.com> - 2011-04-26 13:44 -0400
  Re: File real location unruh <unruh@wormhole.physics.ubc.ca> - 2011-04-26 17:52 +0000

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