Resolving '????????' users and groups

[Larry Hall (Cygwin)]

On 3/2/2010 10:25 PM, Wes Barris wrote:
> Larry Hall (Cygwin) wrote:
>> On 3/2/2010 9:21 PM, Wes Barris wrote:
>>> Dave Korn wrote:
>>
>> <snip>
>>
>>>> Do you *actually* own the files? What kind of drive is this; network or
>>>> local? NTFS or FAT?
>>>
>>> This is a second drive in my XP system. The drive contains all of my
>>> data. One of the folders/directories on this drive is what I use
>>> as my home directory. It has an NTFS filesystem. I map my home
>>> directory on this drive to a drive letter so it shows up in
>>> Windows Explorer as a mapped network drive even though it is a disk
>>> physically on the same system. This is a relatively new disk
>>> (and computer). I copied my all of my data from my previous computer
>>> onto this disk in this new computer.
>>>
>>> I've always thought that I actually owned the files. The Windows
>>> security tab says that I own them. It wasn't until I installed
>>> Cygwin that I had any reason to believe otherwise.
>>>
>>> I see that I can do a "chown -R wes" on a directory and it makes
>>> me the owner as far as Cygwin is concerned. Windows Explorer
>>> says that I am the owner before and after doing this. I can do
>>> this to fix all of the files. It's just a bit curious to me that
>>> Cygwin says I am not the owner but Windows does.
>>
>> How was the data copied? By whom?
>
> I copied the data. I put both disks into one computer and used
> Windows Explorer to drag folders from one disk to another.

As long as that was your target machine, that should have removed
SIDs that the target machine didn't know about.  I can't explain
why any unknown SIDs would be left.

>> The simple answer to the question of why Cygwin doesn't know you're
>> the owner is likely to be that the SID of the owner of these files is
>> not listed in '/etc/passwd'.
>
> Thanks. That is actually how this thread got started. My SID in
> my /etc/passwd file does not match that of my files. Evidently,
> the way I copied my files is incompatible with Cygwin.

Hm.

>> Get it in there using 'mkpasswd' and
>> Cygwin will show you that user as the owner.
>
> mkpasswd shows an SID that is evidently different from that of my
> files.

If you know where the SID came from and can run 'mkpasswd' on
that machine, you should be able to take the right line from
that file and move it into the one on your machine to make
Cygwin show you a user and group that it knows about.  But if
your target system really doesn't have that SID, then this is
largely machinations for the sake of cosmetics.  In other words,
if you know the SID involved, you can simply type it into
'/etc/passwd' with a new, valid and concocted entry too but
I'm not sure that helps.

>> Since you changed the
>> owner already, this is likely moot at this point though.
>
> If I re-install Windows on the same computer does the SID of the
> machine change? Or is the SID tied to the hardware? If it changes
> with a new install that would explain my problem.

How it's computed seems to be a bit of a secret but I would say
you can't be guaranteed of the same SID after a re-install, no
matter how similar (or the same) the machine.  That doesn't mean
you cannot get a machine with the same SIDs.  Cloning is the most
common way to make this happen.

-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
216 Dalton Rd.                          (508) 893-9889 - FAX
Holliston, MA 01746

_____________________________________________________________________

A: Yes.
 > Q: Are you sure?
 >> A: Because it reverses the logical flow of conversation.
 >>> Q: Why is top posting annoying in email?

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