You should know that when you "delete" a file on your computer in your operating system, whether Linux, Windows or Mac, the file is not really deleted or overwritten until the space is needed for new data. This is beneficial when you accidentally delete a file, but is dangerous when you "delete" a sensitive file and falsely feel like you're safe.

Linux has the command shred which overwrites files with random data, which solves this issue. You can also output /dev/urandom or /dev/zero to blank or distort empty space on a drive.

Even in the case of encrypted drives, it's a good idea to use /dev/urandom or obscure unused or previously used space to prevent metadata leakage about how much you've stored on the drive or what used to be on it, in a way that could tie you to an important USB drive or computer.

00:00 No data's every really gone!