I f you have ever accidentally deleted a file, you are aware of the importance of taking care to prevent this occurrence by being prepared. What you may not be aware of, though, is the way in which files are deleted, and the possibility of retrieving them intact using the DOS Undelete utility which comes with later versions of DOS. |
When a file is deleted, you may think that the data or program is gone for good, erased. Actually, this is not the case at all. The only change made immediately to the file when it is deleted is to change the first letter of the filename. Unbelievable? But it's a fact. The first letter of the filename is replaced by a Greek letter, sigma, if and when a file is deleted. Recovery, then, simply requires detecting files which have first letter sigma in their filenames. Then, the user can be asked to choose a new first letter for the filename, which then ensures that the file will be seen again by DOS. Recovery is performed by a utility known in DOS as Undelete.
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In practise, undeleting files is not always this simple. The problem is, while files which have recently been deleted are still intact (except for their filename) immediately following deletion, subsequent write operations performed to the same disk can write new data into the location of the deleted files' contents. The reason is that once a file is deleted, it is no longer protected from overwriting. Even if the disk has been written to, though, deleted files may still be intact. Don't assume they are gone. Assuming that they are recoverable, typing "undelete " at the DOS prompt will detect them, and they can then sometimes be restored.
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