7/10/18
7:00 am

How Mac Trash Handles External Drive Files

The way the Trash works is pretty straight-forward for your internal drive. But how about files on external or removable drives? Any file you put in the trash remains on that drive, but appears as a aggregated list when you view the Trash folder. You can only see files in the Trash on the same computer and user that threw them away.

You can also watch this video at YouTube (but with ads).

Video Transcript: So here's something that seems pretty straight forward until you start to think about it. Say you put a file in the trash. I'm going to drag a file here and I can dump it in the trash. Looks like it's gone. Says this folder has zero items in it. But I know that it's still there in the trash. I can click on the trash and there it is. I can drag it back or somewhere else. I can even Control click on it and I could say Put Back. That all makes sense. 
But what happens if this is an external drive or a removable drive. In this case it's a thumb drive.  A USB thumb drive. I'm going to drag this to the trash. What happens if I eject the thumb drive. If I look in the trash now with the thumb drive in there, there is the file in the trash and any other files that I would have thrown away on my main hard drive would be in here as well. But if I eject the thumb drive you can see it goes away. It's not there anymore. That's because the file is still on that external drive. Putting it in the trash doesn't move it to some trash folder on your local drive. It's in a special location on that external drive.
So what you see as the trash is actually a list of files that are on any connected drives that you have thrown in the trash. So if you have, say, an external drive, an internal drive, and maybe a USB thumb drive and you have items in the trash from all three of them you're going to see them in a big list here. But you'll only see the items for the drives that are connected. So disconnect one of those drives and those items disappear.
Now if I reattach that drive it will reappear in the trash because now it's connected to that drive and there it goes. There's that item that's reappear there in the trash. Now here's something else that's interesting. There's actually more than this one item in the trash on this external drive. Where is it because we only see one. Well I used this external drive on another Mac and I threw items from that Mac in the trash. When I did that it put it in the trash from the drive but it doesn't give permission for other users and other computers to see those items. In order to see those trash items I need to put it back.
So, if I were to eject the drive now, stick it in another Mac you would not see this file anywhere. It wouldn't appear in the trash. There would be no way to recover it on that Mac. You have to put it back in the same user and on the same Mac in order to recover that file out of the trash. This is great for security. If you throw something away in the trash and then you give that drive to somebody else they can't get what's out of the trash and view it. You should empty the trash to make sure that that file is gone but at least you know if you make a mistake that file won't be accessible by anybody else.
One more thing I want to show you about the Trash. Suppose I drag these three items from my local hard drive into the trash. Now I know I've got this one item here and it's from that thumb drive. I can actually get information, Command I, and it will say where, thumb drive, right there. Whereas if I select this item here then when I get information on that it says where, and my local iCloud Drive. So I can tell where these items come from.
Now suppose I want to empty trash but for some reason I don't want to delete these just yet. I only want to delete the one on this USB drive so I can give it to somebody. Well, you can actually do that. If you Control click on it there is the option to Delete immediately and that will delete that one file immediately and leave the rest of your trash untouched. It's a handy way just to clear up just those items that are on that drive or just a particular item you really want to delete while leaving the rest of your trash intact.

Comments: 18 Responses to “How Mac Trash Handles External Drive Files”

ARC

6 years ago

Awesome topic. I always wondered why Mac behaves this way, makes sense now. Especially the part about security and trash from one user not being visible to another.

Fred Balfour

6 years ago

As Gary sez, a “trashed” file on external device stays until owner deletes it. So, User#1 trashes 5mbyte file on 10mbyte thumb drive, & dismounts. User#2 mounts drive, sees empty 10Mb drive with 5Mb free. User#2 pays Patreon for MacMost & knows most likely scenario is another user’s file(s) are there. User#2 works at a forensics firm & knows that she can read “trashed” invisible file if she wants to. So beware. Only way for user#2 to get rid of trashed file is to reformat drive, correct?

Gary Rosenzweig

6 years ago

Fred: Yes, reformatting the drive will get rid of everything. When making this tutorial, I was thinking of "users" as accounts on your Macs. Naturally, if you plan to give a USB drive to another person and you don't trust them, then you should make sure that you empty the trash/reformat the drive, etc.

Bob Hunter

6 years ago

This also explains how a thumb drive seems to hold less and less over time if you never empty trash while the thumb drive is plugged in.

Patrick McEnroe

6 years ago

Hi Gary, what if I give the thumb drive to a Windows user? Will my trash still be secure? Thanks, Pat.

Gary Rosenzweig

6 years ago

Patrick: If your drive is formatted for macOS, then a Windows user won't be able to do anything with it. If it is formatted for Windows (FAT32, etc), then I'm not sure if there is a trash at all -- files may just be deleted. You'd have to try that and see.

Louise Kienast

6 years ago

I can't remove an InProgress file from trash. It says "The operation can't be completed because the item "folders" is in use.

Gary Rosenzweig

6 years ago

Louise: Try quitting all applications until you quit the one that is using this item. If you quit everything and you still can't empty the trash, try restarting.

Louise Kienast

6 years ago

The file is from my external hard drive used with Time Machine. I have learned that you can't delete these files from the trash since they are not actually part of the computer trash but the hard drive trash.

Gary Rosenzweig

6 years ago

Louise: Hard to say what you should do without knowing what type of file it is, what created it, and why it won't delete. Did you try simply getting Info on that file and changing its permissions? Also, look at: https://support.apple.com/en-us/HT201583

Louise Kienast

6 years ago

Thanks Gary,

I will try later today and see if it works. The file is a package file. (2018-09-23-174423.inProgress). It is located in My Time Machine Hard Drive .Trashes Trash. Size zero bytes. It was created by a failed backup in Time Machine. I have not backed up in six months and this behavior has happened before. I was able to delete the file I think when it happened before. (the empty rectangles above are supposed to be right facing carets).

Gary Rosenzweig

6 years ago

Louise: You haven't backed up in 6 months! That's a far far more serious issue than a file stuck in the trash. I would think about clearing that drive up (or getting a new one) and starting a new backup immediately. Then I would let it back up normally (hourly) after that. It is a very bad idea to go without a backup.

Louise Kienast

6 years ago

OK, I'm going out to get one now. I do back up important files, but I don't use Time Machine. I just move individual files into folders so they look like my computer files. That means I am not copying the applications nor most of the unimportant files, just the ones that are important. I do that often but not hourly. Thanks for the advice.

Louise Kienast

6 years ago

Success! Thanks to a thunderstorm I decided to try once again to back up. Just finished. I'll keep it up. Now I just have that silly file in the trash I can't delete. I saw that some have used the Terminal to remove the file from the hard drive. Is that a good idea? I don't like to do something just because it is mentioned on YouTube.

Gary Rosenzweig

6 years ago

Louise: Try the method in that link I included above.

Louise Kienast

6 years ago

I tried each suggestion on the link you sent. I still can't remove the file that way. I found this topic: how to get rid of time machine backups in trash, with a link to a YouTube video using Terminal. I still don't know if this is a good method. The external hard drive is fine and I can use TM even with that file in the trash, so maybe it doesn't matter. It only shows up when I connect the external hard drive anyway.

Gary Rosenzweig

6 years ago

Louise: I would only use Terminal for things like this if you feel comfortable. I'm surprised running disk First Aid on the drive didn't work.

Louise Kienast

6 years ago

WOW! I have been backing up with TM and today I installed Mojave. I tried once more to delete that file and guess what? It's GONE! I think sometimes you have to just wait. Perhaps the update fixed the problem.

Comments Closed.

How Mac Trash Handles External Drive Files

Comments: 18 Responses to “How Mac Trash Handles External Drive Files”

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