LinuxSA Mailing list archives

  From: Stephen White <spwhite@chariot.net.au>
  To  : <linuxsa@linuxsa.org.au>
  Date: Tue, 3 Jul 2001 12:23:03 +0930 (CST)

Re: Basic NFS Question

On Mon, 2 Jul 2001, Alan Kennington wrote:

> Where symbolic links and NFS become interesting is where you
> make a symbolic link outside a file system on the _exporting_
> side of the NFS relation. Then can the importing side follow
> that link into the file system which is _not_ mounted
> by the importing host and _not_ exported by the exporting side?

Let's take a step back...

All files have no names, only inodes.

A directory entry maps a name to an inode.

A hard link maps another name to the same inode.

A soft link maps a name to a text string. Eg:

[steve@localhost steve]$ ln -s "some random text" a; ls -l a
lrwxrwxrwx    1 steve    steve          16 Jul  3 12:09 a -> some random text

The C library and parts of the OS will automatically re-apply the text
string as a filename, thus achiving a linking effect.

So when considering imports, exports, and NFS mounts, the only question
that needs to be asked is "is the filename valid when it's accessed?".

So to answer your question, the answer is "yes". I used this technique
to switch groups of consoles from one baseline to another, by setting
softlinks on the NFS server that pointed to local files on the client
hard drives. The server couldn't access those files itself.

I wouldn't recommend this as a general purpose solution, since it's not
a terribly nice combination of centralised configuration and distributed
dependency. If the NFS server kicks the bucket, everything does.

-- 
  spwhite@chariot.net.au

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