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I have user A created on Machine 1 and user A belongs to group G1. I have user A also on Machine 2 and user A belongs to group G2. A directory on Machine 3 (not in my control) has rwx permissions for user A. Should user A be able to write to that directory from both machines??? Or does it matter which group user A belongs to?? I thought the groups won't matter, but it seems that from Machine1 I can write into the directory, but I can't from Machine2.

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migrated from Dec 4 '11 at 23:00

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up vote 2 down vote accepted

I'm assuming you're using NFS here.

If it's mounted read-only, nobody on the mounting machine will be able to write to it no matter what the permissions are.

If the UID of User A is different on the two machines, that may also cause the issue you're seeing. (There are many ways to get the UID of a user. One way is to log in as the user and use id -u.)

If User A is the root user on the mounting machine, that may also cause the issue you are seeing. The root user is typically mapped to an unprivileged user for NFS for security purposes.

There are probably at least a dozen other possible causes, but those are the things that leap to mind.

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Thanks for the prompt reply!!! User A is not the root user on the mounting machine (or the other 2 machines for that matter.). As for UID's where do I check them from?? My user doesn't seem to be listed in /etc/passwd. I'm using Redhat 5 Linux – StuckAgain Nov 28 '11 at 6:32
I've added information to my answer about how to get the user's UID. (This question probably belongs on ServerFault rather than StackOverflow.) – Trott Nov 28 '11 at 6:38
You were right!!! It was a UID mismatch. Resolved the conflict after syncing up the same. Thanks a lot. – StuckAgain Nov 28 '11 at 9:24
@Trott: Actually, it's probably a better match for Unix.SE. Or, if these are Ubuntu machines, AskUbuntu. I'm guessing StuckAgain is not a professional sysadmin, the main target audience for ServerFault. – derobert Nov 28 '11 at 14:21

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