Re: dd, physical devices, permission denied

[Corinna Vinschen <cygwin at cygwin dot com>]

On Wed, Sep 19, 2001 at 06:12:46PM -0500, Jeff Bastian wrote:
> 
> I see that the naming mechanism for drives has changed from //X to
> /cygdrive/X with the newest release.
> 
> However, I'm having problems with the raw disk devices themselves.
> 
> I was using Cygwin B20 until I upgraded today.  The old method
> doesn't work:
> 
>   [Administrator]$ dd if=dos622.img of=//./a:
>   dd: opening `//./a:': Bad address

Excerpt from the Online User's Guide:

http://cygwin.com/cygwin-ug-net/using-specialnames.html

  To access those devices you have to mount them and you have to use
  the posix name of the device to be recognized by Cygwin.

> So, I tried just 'a:' for the device, but it says permission denied:
> 
>   [Administrator]$ dd if=dos622.img of=a:
>   dd: opening `a:': Permission denied
> 
> Trying another method yields the same thing:
> 
>   [Administrator]$ mount -s -b a: /dev/fd0
>   mount: warning - /dev/fd0 does not exist.
>   [Administrator]$ dd if=dos622.img of=/dev/fd0
>   dd: opening `/dev/fd0': Permission denied

So you forgot to check the remaining method:

	mount -s -b //./a: /dev/fd0

I'm going to remove the need to mount the devices in one of the next
Cygwin versions but note that you will have to use the POSIX names
of the devices to get raw device support regardless.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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