再和eveline 和辣妹讨论recover deleted file in Unix operating system

对于辣妹是否有钱， 是否真的辣， 我一点都不关心， 因为那与我无关。 但对于hacker是否可以hack in 一个 web application， 去recover deleted files， 我比较关心， 所以昨晚用了几个小时去辩论， 今天早上还和我LG 讨论这个问题。

辣妹说：
If a hacker can get into the database which hosts images, that means he can get that particular image eventually.

Also if the image is cashed in any other website like google engine, that is also accessible by other users.

Delete is a user function that does or does not do what the end user thinks it is doing.

看了上面的话， 我真的感到很惊讶。 因为， 我知道在大型系统里， image files 都是放在server 的file system里的。 database 放的只是 file reference。 而且， 那个server， 也不是你家里的PC， 可以那么容易找到那些free space 去recover data的。

下面看一下专家是怎样说的
Recovering Deleted Files in Linux/UNIX:

Many people think that recovering files in Linux is not possible, this is not true. It is not impossible to recovery deleted linux files, it is just rather difficult and not always successful. Unlike Windows it is much harder to recover files that have been accidentally deleted in Linux. UNIX based systems assume the user is more advanced and places more responsibility on the users to make sure their are correct. While in Windows you have the simple recycle bin, and then the ease of searching for deleted files by name and recovering them things are more complicated in Linux and there is no true undelete utility. The best policy is a very good backup policy, however when that does not happen you still have an opportunity to recover the files.
Limitations on Recovering Deleted Linux/UNIX Files:

Unlike in Windows deleted files do not retain their names or extensions so it can be difficult to find the necessary deleted files that you want back. Using the correct software you will be able to find deleted files by file size and date of deletion so it is possible to narrow down the possible files that you need. It is also important to recover the files as soon as possible because once the space that the file had occupied is overwritten is gone forever (the same goes for files deleted in any operating system).

ttp://www.datarecoverypros.com/linux-deleted-files.html

除了上面所说的难处以外， 放照片的网站， 并不是只是为一个人服务的， 在一个user delete file 的同一分种内， 别的users也很可能会add 他的file， 那这个user 原来的data 就会被overwritten 了， 这样无论hacker有多天才， 也只能望那被over written 的space 轻叹了

这个问题说来说去， 我也真累了， 就此打住吧