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Re: restoring FC1 to *new* partition from tar archive



On Sun, May 09, 2004 at 09:25:49PM -0500, Jeff Vian wrote:
> Ownership is stored on the system as numeris and is part of the inode data..
> When displayed by ls or similar utilities it uses the values in the 
> passwd and group files to provide names for the user to see in the 
> listing. The chown command also translates the text user name to his UID 
> befroe assigining it to the file.  The find command has an option to 
> search for files with the numeric UID or name.
<...>

Yes, I know all that.

> tar writes the raw data. It does not have any idea of the names 
> associated with the numeric UID on the file.

Yes, it does. When creating the archive tar also stores the symbolic name
and group.

Well, at least GNU's tar does. Please see the info page for tar.

Of course, if creating the archive with the option "--numeric-owner", then
no symbolic name/group user stored and there's no need to worry when
extracting. But it's not usual for people to specify --numeric-owner.

> The link between the numeric values on the file and the names they are 
> associated with is provided by the system and use of /etc/group and 
> /etc/passwd.

Yes, and when extracting files from the archive tar, if without the
--numeric-owner option and if symbolic names for user and group in the
archive, will use the current system's /etc/group and /etc/passwd, that
may be different from the to be extracted etc/group and etc/passwd.

> I had to get this straight definitively when I merged user accounts from 
> 2 different ISPs that had many overlapping UID and GID numbers, with the 
> names mismatched between the sites.  It took a lot of planning and 
> creation of custom perl scripts to merge the accounts..

If you had GNU's tar, that should had been easier. Maybe you didn't, or it
didn't work like that then, or the archives weren't created with the
symbolic names.

But my experience with the discussed procedure made me recomend that
option.

Regards,
Luciano Rocha



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