當資料從回收站中刪除時會發生什麼？

大多數情況下，除了知道已刪除的檔案已經不在我們的視線之外，我們很少會想到已刪除的檔案，但當我們刪除這些檔案時，這些檔案會發生什麼呢？今天的超級使用者問答帖子回答了一位好奇的讀者關於刪除過程的問題。...

大多數情況下，除了知道已刪除的檔案已經不在我們的視線之外，我們很少會想到已刪除的檔案，但當我們刪除這些檔案時，這些檔案會發生什麼呢？今天的超級使用者問答帖子回答了一位好奇的讀者關於刪除過程的問題。

今天的問答環節是由SuperUser提供的，SuperUser是Stack Exchange的一個分支，是一個由社群驅動的問答網站分組。

照片由傑拉德的世界（Flickr）提供。

問題

超級使用者讀者Shea A.想知道計算機上刪除的檔案會發生什麼情況：

Correct me if I am wrong here, but when you delete something from your PC, all your computer does is write over some of the binary with 0’s replacing the 1’s (or something to that effect). So when you send something to the Recycle Bin, it writes over part of the file, then when you delete the file from the Recycle Bin, it writes more?

整個檔案刪除和回收站過程是如何工作的？

答案

超級使用者貢獻者Boann和Mary Biggs為我們提供了答案。首先，博恩：

Neither operation writes over the file. Moving a file to the Recycle Bin does just that, moves the file. Its contents are left completely intact.

Deleting a file from the Recycle Bin (or deleting it directly using Shift+Delete) removes the file name entry from the folder. The part of the disk previously occupied by the file is not modified or overwritten and still contains the file data, but that data is no longer linked to a file name. That spot on the disk is recorded as “free”, however, so future writes to the disk can reuse that space, and if you keep using the disk, the space will almost certainly be overwritten eventually.

In a case where you need to prevent recovery of deleted data, special tools exist to overwrite the data securely. That is not done by default because it is slow and increases wear on the disk.

接著是瑪麗·比格斯的回答：

A file is in two parts:

A directory entry which records the file name and also contains a list of the blocks on disk which contain the data contents of the file. The operating system then “knows” that these blocks are in use.
The actual blocks which contain the data contents of the file.

When a file is deleted:

The list of blocks in the directory entry are marked as “free” and returned to the operating system. The directory entry is deleted, so the file “disappears” from the file system.
The actual blocks are not touched, so the data contents of the file remain untouched until some other new file overwrites them. This is the reason that file recovery software can often rebuild deleted files (but only if it is used soon after deletion).

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