Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262422AbUFBMj3 (ORCPT ); Wed, 2 Jun 2004 08:39:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262438AbUFBMj3 (ORCPT ); Wed, 2 Jun 2004 08:39:29 -0400 Received: from chaos.analogic.com ([204.178.40.224]:45440 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S262422AbUFBMj1 (ORCPT ); Wed, 2 Jun 2004 08:39:27 -0400 Date: Wed, 2 Jun 2004 08:39:15 -0400 (EDT) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: "Piszcz, Justin Michael" cc: linux-kernel@vger.kernel.org, Al Piszcz Subject: Re: How come dd if=/dev/zero of=/nfs/dev/null does not send packets over the network? In-Reply-To: <5D3C2276FD64424297729EB733ED1F7606243695@email1.mitretek.org> Message-ID: References: <5D3C2276FD64424297729EB733ED1F7606243695@email1.mitretek.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1308 Lines: 42 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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/