On Linux, how to wipe your hard drive?

On Linux the best way to definitively erase data on a hard drive is to use the command-line utility shred. It will overwrite all the blocks on the device with random data three times:

sudo shred /dev/sdxx

Here are some useful options:

• -v verbose;
• -n N overwrite N times instead of the default (3);
• -z set all bits to zero after the last iteration.