What happens to the files on your computer when you “empty the recycle bin”?
In: Technology
The file system not only keeps data, but also a record of how to find the data on disk. When you empty, you’re telling the computer to delete that record so it doesn’t know how to find the data anymore. The original data is still there, it’s just that the spaced it occupies is free to be written again.
The computer keeps track of the location of every file. So it knows what areas of the hard disk are being used, and what is free to be used for new files.
When you send something to the recycle bin, nothing changes on your hard disk, and the computer will still treat those areas of the hard disk as in use. This is what allows you to easily recover deleted files.
When you empty the recycle bin, nothing happens to those files, not immediately anyway. However, the computer now treats the area of the hard disk where those files are as available for use. So over time, those areas will get overwritten by new stuff.
if you REALLY want to delete a file from your HDD you need to overwrite it not only once but several times over. Serious law enforcement agencies have methods of recovering data from a HDD even if it has been overwritten three or four times.
When you “empty the Recycle Bin”, you are telling the computer to mark the file as ‘deleted’.
What does this mean? Imagine you are at the school library. There are bookshelves and a card catalog up front, with a card for each book, specifying where the book is. When you mark a file ‘deleted’, you get rid of a book’s card. The book is still on the shelf.
When a new book arrives and space is needed, in addition to adding a new card to the catalog, that old book is subject to being removed and thrown away so the new book can take its place.
Normally a file on your computer can be divided into two parts.
One is the actual file contents, a large blob of stored data somewhere.
The second is an entry in an index of what files exist. That has data to point to the file contents.
When you delete a file to the recycle bin, all you do is set a flag on that index to say it is soft-deleted. The contents still exist on the disk.
When you hard delete a file, all you do is actually completely delete that index entry. The data is actually still on the disk. However, now when some other application asks for space on the disk to write a file, the OS will tell them that the space is free, so they can overwrite it.
Imagine you have a list of movies you’d like to watch.
Every time you watch one, you cross it out. You can still see the name, but you’ve marked it “watched”.
When you empty the recycle bin those files are going from marked as “in the recycle bin” to “deleted”.
The file / movie name is still “there” and if you later want to add something to that movies row, or that files space, you can.
Pretty-much nothing happens to a file when you *move* it *to* the recycle bin. It’s location changes as far as the file-location index is concerned, but that’s it.
When you “empty the recycle bin”, The file-location index “forgets” where that file is, and the storage space where that file is is now free to be overwritten with new information.
Since the file is still there, it can be recovered by using recovery software. Generally the first character in the filename is changed to a character the system chooses to ignore and the file can’t be “seen.” But the recovery software can see the file, rename it, and allow it to be copied over to some other storage space.
The only time a file truly goes away is if its file-space is over-written by a new file, or the file is obliterated through the use of file-shredding software. Shredded files bypass the recycle bin and are just replaced with meaningless, random data. There is pretty-much no way to recover a file after that.
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