[SFS] What's in a UID.

[David L. Anselmi]

During class today David mentioned working like UIDs don't matter.  So I understand that you use 
names instead of IDs everywhere you can.  But is the rest a matter of using software that doesn't 
care, or tricks to hide the differences, or ...?

For example, suppose the USB disk I use to move data between machines uses ext4.  I guess mount(8) 
might have a way to make all the files belong to the user that's mounting it.  But if I want to let 
people own files and control permissions on that disk they'd have to have the same UID on the 
various machines, right?  Admittedly that might be an unusual use case.

Does root still own everything or does selinux let me label some files on removable media so root 
can't see them?  (With a properly configured host of course.  Which may be moot if you plug into a 
machine without selinux.  Obviously the right approach is to encrypt whatever you don't want others 
to mess with.)

Thanks!
Dave