I got a new iMac after my old one died. As my old one was dying I made several Time Machine backups to a 1T G-Drive external. Unfortunately, I must have done it incorrectly because the backups have used up so much of the space on the external that there's not enough room to back up my new iMac to the external. The Time Machine backup for the old iMac could not have been more than 350 GB, so, I am a bit perplexed. Last night I attempted to remove some of the older multiple backups of the same files from the old machine by dragging them to the trash. It seemed to work until I got to the next most recent backup and when the files finally copied over to the trash the window said there were more than 1,500,000 files! After waiting for hours for the trash to empty, I finally gave up when their were something like 1,200,000 files remaining. Am I going to be able to delete these files from this backup and free up space on my external drive so I can backup my new computer, or do I just need to give up and buy a new external?

  • In case you have checked my answer previously please look at it again, as I added several updates.
    – AMR
    Commented Aug 1, 2015 at 19:19
  • Jeff, lets say the name of the external drive when you manually deleted things from the Time Machine backup is 'Backup" all you need is the following command to cleanup the mess: sudo rm -fR /Volumes/Backup/.Trashes/$UID/* Commented Aug 1, 2015 at 19:33
  • Time Machine essentially expects a partition pr machine to backup. If you need to use a disk for multiple machines, partition it. Note that OS X Server appears to be able to control the disk space for each time machine backup on it. Commented Aug 3, 2017 at 13:46

2 Answers 2


Time Machine performs versioning backups at specific time intervals and keeps making backups until it runs out of space on the drive, then it starts to prune away older backups to make room for the new ones.

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The only way that I know of to control the amount of space that any one Time Machine Backup uses is to set up a partition on the drive in Disk Utility and then have Time Machine back up to that partition.

You will not be able to delete some of the time machine backup as it is stored like a database, and it is an all or nothing delete.

Response to Trash Question

If you have 1.2MM files, Secure delete will take a very long time to do this.

If you do not mind that the data will not be overwritten and only the file associations will be removed you can do this to clear out the Trash.


With that warning out of the way, here is how you can do it.

  1. First open Terminal (in /Applications/Utilities).

EDIT step two is for the trash bin in your user directory. Yours is likely on the root of the drive itself. As I don't know what that path will be I can't give you that step. Just replace that path for the one after cd. The file is likely hidden, so if you do not know how to show hidden files I will add the Terminal commands at the bottom of the post.

FROM user3439894 use sudo rm -fR /Volumes/<volume_name>/.Trashes/$UID/*

This will be what the path to your external drive's trash looks like. You will have to figure out the exact path on your drive. You can also skip the drag and drop steps doing it the way user3439894 suggests.

  1. Type cd ~/.Trash and press Return.
  2. Then type sudo rm -Rf followed by a Space (don’t leave out the space). You will need the recursive for to handle subdirectories, etc.
  3. Don’t press Return yet.
  4. Next, click the Trash icon in your Dock to open a window displaying the contents of the Trash.
  5. Select everything in that window and drag it into the Terminal window; this action adds the paths of all those files and folders to the rm(remove) command.
  6. Now, press Return
  7. Enter your administrator password when prompted

In a moment or two (depending on how much was in your Trash), the Trash icon should return to its empty state.

-- The answer I provided is based on the technique that I obtained from Joe Kissell's article on MacWorld and have used during the times I have not been able to empty my trash bin.

How To Display Hidden Files In Mac OSX


defaults write com.apple.finder AppleShowAllFiles true return

killall Finder return

How To Hide Hidden Files in Mac OSX


defaults write com.apple.finder AppleShowAllFiles false return

killall Finder return

  • Using cd ~/.Trash will not delete the items on the external drive when issuing the rm ... command and in this particular case do not drag and drop all of the objects in the Trash onto the Terminal window! You need to be in /Volumes/<volume_name>/.Trashes/$UID/ and then use sudo rm -fR * although it's probably more safe to just use sudo rm -fR /Volumes/<volume_name>/.Trashes/$UID/* , e.g. sudo rm -fR /Volumes/Backup/.Trashes/$UID/* Commented Aug 1, 2015 at 19:23
  • I had already edited. However for USB externals, Their trash bins do show up in the dock and you can drag out to get the paths for all of the files... But yes, actually specifying the exact path is likely a better idea than drag and drop.
    – AMR
    Commented Aug 1, 2015 at 19:25
  • I still like to cd to the directory first that way if you accidentally hit return before entering the path you don't wipe your Home directory.
    – AMR
    Commented Aug 1, 2015 at 19:27
  • In the case of the OP it has nothing to do with the Home directory and only /Volumes/<volume_name>/.Trashes/$UID/* and you are over complicating things for the OP to resolve his particular issue! Commented Aug 1, 2015 at 19:29
  • And I added that to the edit as I said that I did not know the exact path his external drive would have. I also added your suggestion.
    – AMR
    Commented Aug 1, 2015 at 19:32

I have a utility called Techtool Pro 5. It has an option to recover erases/deleted/trashed files.

I purchased it online during a Macheist bundle. Use another computer to do this as you don't want your imac to overwrite the trash. Micromat - TechTool Pro 5

  • I don't think this answers the question. Jeff Cline wants to delete files from the Time Machine backup.
    – oa-
    Commented Aug 3, 2017 at 10:54

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