Purging a hard drive in Linux

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There is a lot of information available out there on purging hard drives; this is the lower-security, quicker way to do it.

dd bs=1M if=/dev/zero of=/hard/drive/device

This will overwrite the drive with zeroes.

for more security, but a longer process:

dd bs=1M if=/dev/urandom of=/hard/drive/device

Which will overwrite the drive with random data.