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I have some very important files I want to backup before I reinstall my Ubuntu back to 9.04 from the 9.10 (its causing me all sorts of problems).

The files total size is small so im just going to copy them over to Dropbox. Im wondering, when i reinstall Ubuntu and copy them back will there be any issues re the permissions of those files because my old user account which created them and the new user Ill setup on the new install will be different?

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up vote 2 down vote accepted

You are better off if you use tar (with some compression if you wish) and save this to DropBox, then restore from the tar file, and the permissions will be restored.

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There shouldn't be any problem, since it's the same user accessing Dropbox. Though, if there are mproblems, just sudo chmod and sudo chown the files, any you're ready to go.

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He'll probably copy as root, so everything will be root's. And doing the small changes by hand afterward is just the kind of problem he wanted to avoid. – Benjamin Bannier Feb 9 '10 at 18:21

If you re-install, and re-create your user, you're not guaranteed that you'll have the same user ID. (I think ubuntu starts creating user ids at 500).

But it's really no big deal: as @Kami and @Bobby mentioned, a couple of simple commands can restore the ownership.

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no, generally Debian-based systems reserve UIDs <=999 for system accounts, and start user UIDs at 1000 and up. (Ubuntu is Debian-based and follows this general rule.) – quack quixote Feb 9 '10 at 16:44
@quack: I stand corrected; however the point I was trying to make is that you may not have the same uid on a new system as you had on the last one, so you'll probably need to change the ownership if the backup preserves that information. – chris Feb 9 '10 at 17:02
not arguing your point; it's accurate. just adding info. – quack quixote Feb 9 '10 at 20:28

You will lose file's permissions by copying them over Dropbox. Then use chown/chmod/chgrp to restore permissions if something fails.

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