I have opened the following preference files:






None of them mention the volume being used for time machine backups. Any ideas?

2 Answers 2


Time Machine's main preferences can be found at /Library/Preferences/com.apple.TimeMachine.plist (which you listed - but the name is stored there)

The Backup hard drive is actually stored as an data blob(1) under the key BackupAlias. Property List Editor and most text editors (eg. TextMate, SubEthaEdit, BBEdit, etc.) won't show the information after converting the preference list from binary to xml using plutil. However you can use PlistBuddy (available in /usr/libexec/ which is not in the default path) to give you the name of the drive (with a bunch of repeated information):

/usr/libexec/PlistBuddy -c 'Print :BackupAlias' /Library/Preferences/com.apple.TimeMachine.plist

1 - This is the base64 decoded form of a _CFULRAlias to be exact.

  • Thanks. I am able to run this command successfully. Do yo uknow how I would change the volume? Aug 11, 2009 at 9:00
  • Without resorting to using the Time Machine Control Panel? Not really. I don't know how to properly put the data into the .plist though from what I understand it should be similar to what is done for adding items to the Dock from the command line.
    – Chealion
    Aug 11, 2009 at 15:28

You can simply delete the /Library/Preferences/com.apple.TimeMachine.plist file and add your TM drive back again in TM settings panel.

Works for me.


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