> True, but you have to make sure that the passwd/group file is in sync
> for all of the files or there'll be weirdness unless you use
> --numeric-owner.
What do you mean "there'll be weirdness unless you use --numeric-owner"?
GNU Tar stores both the text name, and the numeric ID for users and
groups. It favors the text name if possible and falls back to the
numeric ID if the name is unavailable.
This means you can have three machines each with three users. Each
of the users could have been added to the machines in a different
order. (So on MachineA, UserA is 1000, etc.) However, GNU Tar will work
properly in this case, and the files will not get confused.
This actually makes GNU Tar handy to use if you ever find yourself
working with a machine where the user or group IDs have gotten totally
out of hand and you want to clean them up. (For instance, if you're
using a system where useradd always picks the last user ID, and some
fool of a prior administrator saw an example giving postfix a user ID of
54321 and copied that in as-is.)
Of course, if you over-write a passwd file on one machine with a passwd
file from another machine you're basically screwed. It isn't Tar that
screws you, it is just that you should never-ever do it. (So you're
basically screwing yourself. It is easy to forget this and do it without
thinking -- I know I've done it before.)
Most Linux distributions don't guarantee the IDs of even the system
users/groups. With the system IDs you may be able to find a tool to help
you correct them. With the user IDs, you'll basically be forced to chown
the home directories to who they're expected to be, and just correct any
other files to a user/group that will allow the user community access
from there.
Cheers,
Steven Black
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