Take out the Trash
Mac Tip#34/19-Dec-2001

Last week you dragged a document to the Trash and saw the Trash basket overflow. This hasn’t removed your file from the computer though and if you need the document again drag it back out.

If you truly don’t want the document any more then all you have to do is Empty the Trash. You can do that from the Special Finder Menu. Update for Mac OS X: empty the Trash from the Finder menu.

This behaviour is rather like the physical wastebasket in your office. You might throw a letter away but if you need to read it again you can just pull it back out of the bin. Once you empty that wastebasket into the rubbish bag though and the rubbish collection take it away then the letter is actually gone.

The analogy breaks down here though, because even though the document seems to be gone, in fact it isn’t. Your computer behaves more like a video tape. I might record a TV show and make a note on the label. This is like saving a document, and the computer notes the name in its database. It also notes where on the hard drive the file is saved.

Later I watch the tape and erase the show’s name from the label. This is like putting the document in the Trash and emptying it. To all intents and purposes the tape is now blank (the document is gone).

In reality though the tape isn’t actually blank. If I put it in the video I can still watch the show. After all, I only erased the name, not the tape itself. Similarly, the computer hasn’t actually erased my document. It’s still there, it’s just that the computer has noted that the space where it’s stored can now be used for other purposes.

It’s only once I record something new over the top of the TV show that my original programme is gone. Similarly, it’s only once the computer saves another document in the space previously used by the original document that the original is actually wiped out.

This means two things:

1) If you trash a document and empty the Trash then realise that you’ve just deleted the most crucial item on your hard drive you should follow these steps:

1. Don’t panic
2. Don’t use your computer for any reason at all
3. Call your computer support / repair person
4. Organise a better backup strategy

2) If you want to sell your computer (or give it away) just putting documents in the Trash and emptying it doesn’t guarantee that others can’t retrieve your files. For your files to be truly gone either you need to use a piece of software designed to totally delete files or you need to reformat your hard drive.

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