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Date: Wed, 21 Mar 2007 12:37:33 -0700
From: Greg KH <greg@kroah.com>
To: Paul Rolland <rol@as2917.net>
Cc: "'LKML'" <linux-kernel@vger.kernel.org>
Subject: Re: Why is /dev on a different filesystem ? [Kernel 2.6.20.3]
Message-ID: <20070321193733.GA18778@kroah.com>
References: <04ea01c76bed$11b0d050$4b00a8c0@donald>
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On Wed, Mar 21, 2007 at 08:13:50PM +0100, Paul Rolland wrote:
> Hello,
> 
> I was trying to backup a machine using tar and the --one-file-system option
> and I was getting an archive without /dev, but tar was spitting :
> /dev: file is on a different filesystem; not dumped

That is probably because your distro is using udev which usually means
tmpfs is mounted at /dev/

> So, I had a look at the code in tar, and the comparison is done on the
> stat.st_dev field... 
> I then wrote a simple program to stat("/", ...) and stat("/dev", ...),
> and got :

What does /proc/mounts show?

thanks,

greg k-h