UID conundrum

[tmetro-blu-5a1Jt6qxUNc at public.gmane.org (Tom Metro)]

jbk wrote:
> The UID that was assigned to backuppc in F10 has been usurped by
> another program in F12. 
...
> I have yet to boot into the F12 install.
> So, is it possible to edit the UID's and not effect the ownership of key 
> files if I have yet to boot into the system. When do UID's become 
> effective?

My expectation is that packaged files either have a UID assigned in the 
package (like tar or zip), or a symbolic name to UID mapping happens on 
extraction, either implicitly (set to current user) or explicitly (via 
installation script).

Either way, the UID (and the corresponding /etc/passwd entry for the 
conflicting user on F12) should be set as the relevant packages got 
installed, and when/if you login is irrelevant.


> I either have to not test my install and just change the UID on all
> the backup disks to match the new assigned UID, which takes an hour
> or more per disk, or I have to change the UID for the conflicting
> programs by editing the /etc/passwd file and group file entries.

In the latter case, I think you have to do more than just assign the 
conflicting user a new UID. I think you also need to run a recursive 
find over the file system and update any existing files to use the new UID.

That may be faster/less work than modifying your backup disks, but 
you'll have to repeat it if you do a future (from scratch) OS install.

Perhaps the best option is to use a mount option when mounting the USB 
disk to override the UID and force it to be something else. (uid= option 
supported by some file systems. Probably ways to do the equivalent with 
other file systems. This must be a common problem for USB disks.) If all 
the files on the USB disk have the same UID, that should be an easy 
workaround.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/