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I have a Time Machine backup folder on an external drive. I'm done using Time Machine forever, and I just want to access those files in Finder without all the restrictions placed on "backup" files.

Is there a terminal command I can run to give me all permissions to delete, move, etc?

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3 Answers

up vote 1 down vote accepted

EDIT: According to @Ken Arnold in the other answer to this question, this technique will not work due to Time Machine backups being locked down by ACLs. I can't guarantee this, as I haven't checked it, but it's worth noting before you proceed with this answer. :ENDEDIT

Based on a quick look at my Time Machine backup, all you should need to do is take ownership of the files.

If you navigate to your Backups.backupdb, you should see a folder with the name of your machine on it. If you cd into that folder, you will find a long list of folders that correspond to every backup Time Machine has made.

Due to the way Time Machine works, each of these folders contains a complete representation of the state of your machine at that particular point in time. To get full permissions to read/write etc, you should simply take ownership of one of the folders.

Suppose you just want the latest backup folder, which OS X has helpfully created a symlink for. In that case, the sequence of commands (with a generic username on my machine) would be:

cd /Volumes/Backup/Backups.backupdb/Lukasa's\ Macbook\ Pro/
sudo chown -R USERNAME Latest

An alternative would be to simply take ownership of the entire backup history, in which case you would use:

cd /Volumes/Backup/Backups.backupdb/
sudo chown -R USERNAME Lukasa's\ Macbook\ Pro

An alternative would be to enable the root account and from there you can mess around with the files to your heart's content. Don't forget to disable root once you're done, and for the love of all that is holy don't ever type rm /.

PLEASE READ:

I haven't tested this on my own Time Machine backup, as it's pretty extensive at this point and I'm quite attached to it. However, it's possible that some issues might occur with the nature of the Time Machine backup. In OS X, Time Machine uses hardlinks to reproduce unchanged files and directories. This means that each file contains the entire filesystem as it was at that point in time. However, OS X does not allow hardlinking to directories outside of Time Machine. I can't honestly say what affect this will have: possibly none, but I can't rule out unexpected behaviour. Just a warning.

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There's a lot of misinformation out there about Time Machine backups (Lukasa's answer is actually pretty good by comparison); I've identified what I think is actually going on and hope to post some about that soon. But in the mean time, note two things:

  1. Lukasa's answer unfortunately won't work. Time Machine backups are locked down using ACLs. You can clear them, but then you'll have to watch out for the other caveat:

  2. Time Machine hard-links directories. Normally this is something that Thou Shalt Not do, because changes in one directory cause (what look like) changes in some completely separate directory. Time Machine is structured very carefully to keep this from causing problems, but if you go poking around in it yourself, you're on your own.

That said, it should be possible to write a script to replace the hard-linked directories with directories of hard-linked files, which will just take up a bit more space. I may try to make that script someday; upvote the question and this answer if you'd be interested in it. (Or some SU admin tell me the proper way people should be making such requests.)

EDIT 2011-07-26: Hard links on HFS+ are awful awkward beasts. They're actually stored in magical places, and simple things (like moving them around) that would be perfectly fine on, say, ext3 fail inscrutably on HFS+. And it turns out that deleting the last hard link to a file doesn't turn it back into a normal file either. The script I refer to would end up having to look like: copy each file, remove the original. Yuck, but that's effectively what I'm doing with my old Time Machine backup now. I'm still willing to write up what I've learned, if somebody bugs me about it.

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I didn't know that the Time Machine backups were under ACLs. +1 for that, and I'll edit my answer to reflect it. –  Lukasa Jul 13 '11 at 21:27
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Just copy the folders containing your info to another place/drive. Erase the Time Machine backup drive with disk utility.

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