[dzp111]

I'm aware that when I empty the Trash securely, that "OS X uses a seven-step algorithm to prevent the data from ever being recovered:files from your hard drive, preventing them from being recovered.."

But today I securely emptied my trash with one item in it (application Transmission). The progress bar then showed that it was deleting over 350 items.

My question is, did the OS delete all affiliated/invisible files related to Transmission app? If not, is there a problem?

(Transmission was in Trash after upgrade of said app.)

[tooki]

Applications are made to appear as a single file, but are in fact something called a Package, which you can think of as a sealed folder containing all the resources that comprise the application. If you right-click on an application, you can select Show Package Contents and peer inside.

So the 350 items you saw were the old Transmission and its component parts. And yes, it'll delete them all, since deleting a package is, in actuality, deleting a folder.

Applications aren't the only packages around: iWork document files, your iPhoto library, installer files, system extensions, and even some Read Me documents on installer discs are all packages.

[dzp111]

Thanks tooki. It explains a lot (everything actually).

My next question would then be, if I just emptied trash (not securely) would the affiliated files in package remain on drive?

[Hal Itosis]

Originally Posted by dzp111 

But today I securely emptied my trash with one item in it (application Transmission).
The progress bar then showed that it was deleting over 350 items.

I see from your sig you're using 10.5.5, and... tooki's answer is certainly quite correct.

However, Leopard (10.5.0) introduced some odd behavior to Secure Empty Trash which didn't exist in Tiger.
And Finder (in the initial release) would actually hang, while deleting more files than were visible in the trash.

Even today (I too have 10.5.5) some remnant of this quirk remains.
Try it for yourself:

• Start with an already empty trash, and then put a single *file* in there.
  (I'll use Terminal): touch ~/.Trash/test-secure-delete
  Okay, now my trash contains a single "zero byte" file.
   
• Choose Secure Empty Trash from the Finder menu, and the little window pops up...

  
  Emptying the Trash...
  [=======
  Items to delete: 20

20 items!?!? Yep... that's what I get.
Others get 13 items. Some more, some less.

[dzp111]

Hal Itosis, I'm not into the Terminal thing but I hear what you're saying.

Yesterday I securely emptied my trash with only a few items in it. It then hung at 22 items to delete (several minutes). I tried to stop it but to no avail. My only way out was to Relaunch the Finder. Then I right-clicked the Trash and emptied it.

Strange.. Maybe the OS was attempting to delete an item(s) while in use? Not sure, but it's all good today.

[Veltliner]

As OS X is overwriting the content to permanently make it unreadable, that takes a while.

Take a couple of large files, say 50Mb each, and then select secure empty trash.

You will have a good wait, because it takes a while longer to overwrite a 50Mb file.

If you click stop, it'll still have to delete the one file it's overwriting, and doesn't stop in mid-overwriting. Because this would leave a partial file somewhere on your computer, still readable, and that's what you want to avoid.

[dimmer]

My next question would then be, if I just emptied trash (not securely) would the affiliated files in package remain on drive?

No, to the Finder it's just another folder.