Fedora mount a corrupted Win Fat32 (vfat) file system

[Jeff Vian]

Rick Stevens wrote:

> Chadley Wilson wrote:
>
>> On Wed, 2004-04-07 at 22:08, Andy Green wrote:
>>
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>>> On Wednesday 07 April 2004 20:45, Chadley Wilson wrote:
>>>
>>>
>>>> I am not looking for a fight but I did it again and it works heres the
>>>> outputs as proof, I don't know maybe I suffer from a bug that works in
>>>> my favour :~}
>>>
>>>
>>> Possibly mount ignored your -t iso9660 ?  Type mount on its own to 
>>> see what filesystem type it is actually mounted as.
>>>
>>> Since I'm sure you wouldn't bring this up unless it was true, the 
>>> other possibilities I can imagine is that your ripping action 
>>> encoded it to iso9660 via a pipe to mkisofs, you dd'd it from a CD 
>>> backup in a CD drive, or dd has hidden and mysterious powers until 
>>> now kept secret from me - and from man dd :-)
>>>
>>
>> Ha ha! Did I ever tell you that there's a genie in my PC. :~D
>>
>> Well as I said it must be my buggy system [or the genie] working in my
>> favour for once.
>> I actually created the img from a drive connected to a USB unit with dd,
>> and whats more is I have no idea how to pipe dd to mkisofs so it can't
>> be that.
>> The only thing I can think of is maybe I used mkisofs. But the problem
>> there is I don't know how to use it. I have always been happy with dd.
>> Anyway sorry for the bad advice, at least you can see where I got it
>> from, regardless of how weird it may seem.
>
>
> IIRC, if you used dd to grab the CD's data from a raw device, e.g.
> "dd if=/dev/cdrom of=/some/file", then "/some/file" will be an ISO
> image since you grabbed the sector-by-sector layout of the disk.  This
> is handy to make copies of CDs.  I've done it many times.
> ----------------------------------------------------------------------
> - Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
> - VitalStream, Inc.                       http://www.vitalstream.com -
> -                                                                    -
> -             To iterate is human, to recurse, divine.               -
> ----------------------------------------------------------------------
>
That is certainly correct in some respects.  The output of dd would be 
the same filesystem type as the source when the input is a partition or 
raw when the input is a device. "dd if=/dev/hda of=hda.img" will 
certainly produce a different result than "dd if=/dev/hda1 of=hda1.img" 
even if there was only one partiton defined that used the entire 
physical volume.

Thus, if /dev/hda3 is of type ext3 and you used dd to copy it "dd 
if=/dev/hda3 of=newfile.img" then you mount the new file to view it 
"mount -o loop newfile.img /mnt" the filesystem mounted at /mnt would be 
ext3.   The same thing applies to CDs as already mentioned (and any 
other type filesystem).

OTOH, if you use mkisofs, the input is usually of any readable 
filesystem type, and the output is iso9660.
AFAIK the input to mkisofs is not a raw partiton, but actaully data 
within the partition.  So the filesystem being copied from that way 
would already have to be mounted (Chadley's was not mounted for this 
little recovery exercise :-) ).

Probably Andy's conjecture about mount ignoring the mount filesystem 
type is the best.
Mount is able to guess the correct type of filesystem and auto select 
properly in most cases.