imac Erase files completely

Fellow students, do you think that the paper into the waste basket, and then emptied it thoroughly clean? Actually, you're wrong. After you empty the trash, the file is actually still on disk, but you can overwrite it by writing a new file. That's why the data recovery software can magically restore the data that will be deleted.

Of course, some files we delete if because really do not want to let others see, like the editorial department xx Xuan of the various small movies. This is not, today he came to ask me how to completely delete the file. Here to bring you a simple tutorial to solve this hidden trouble.

The first thing to be clear is that it is not difficult to achieve this goal. It's easy to move through the disk tools that come with the inside of Apple OS X. And does not affect other files on the hard disk.

First open the Finder, find applications, utilities, disk tools. After opening, select the disk you want to process on the left. And on the right side choose to erase, erase the available space. The rationale for this is to unify the hard disk space that has been marked but not altered into 0. The deleted file will be completely overwritten.

The next option is actually to choose how many times to fill in the free disk space 0. The number of times and security is proportional to the U.S. Department of Defense safety standards are 7 times. But it will take a long time.