Secure Erase Hard Drive using DD

The following commands are dangerous! Proceed with caution!

Change /dev/sdX to your drive. Make sure you get the correct drive, or you could wipe you main system.

dd if=/dev/zero of=/dev/sdX bs=1M status=progress

The status=progress part shows how much dd has writen. Helpful to gauge how far along it is.

If you want a more secure way to erase the drive, change zero to random. Makes it slower, but should be more secure.

dd if=/dev/random of=/dev/sdX bs=1M status=progres

Side note, these commands should work in macOS, but you may need to drop the status=progress option.

Create an Image of a SD Card

The following command works on both OS X and Linux.  It creates an image from the SD card called raspi.img which you can later use to clone to another SD Card or just keep as a backup.  It is exceptionally useful for backing up a Raspberry Pi.

Replace “mmcblk0” with your SD cards name.  Take a look at this post if you need help finding the name.

sudo dd if=/dev/mmcblk0 of=~/raspi.img