Re: How come dd if=/dev/zero of=/nfs/dev/null does not send packets over the network?

["Richard B. Johnson" <root@chaos.analogic.com>]

On Wed, 2 Jun 2004, Piszcz, Justin Michael wrote:

> root@jpiszcz:~# mkdir /p500/dev
> root@jpiszcz:~# mount 192.168.0.253:/dev /p500/dev
> root@jpiszcz:~# echo blah > /p500/dev/null
> root@jpiszcz:~# ls -l /p500/dev/null
> crw-rw-rw-  1 root sys 1, 3 Jul 17  1994 /p500/dev/null
> root@jpiszcz:~# dd if=/dev/zero of=/p500/dev/null
>
> 6179737+0 records in
> 6179736+0 records out
>
> Instead it treats it as a local block device?
>
> Kernel 2.6.5.
>

First, /dev/null is a device file. Can you access a remote
device over nfs? ... like

		mount chaos:/dev/ttyS0  /mnt
		cat "foo" >/mnt

I think not. Yes it's the exact same thing; /dev/null is a
character device just like /dev/ttyS0, but a bit dumber.
The above used the network to make the essential equivalent
of a sym-link. The open of the device-file, the connection
of the major-minor numbers to the resulting file descriptor
occurred on your local system.


Cheers,
Dick Johnson
Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips).
            Note 96.31% of all statistics are fiction.