OJBs Web Site: Tip

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(Up to OJB's Mac Tips List Page)

Secure Erase Options

To secure erase when that option isn't available in Disk Utility.
For example, for SSDs.
Boot from another disk or recovery mode.
Erase the disk encrypted, with a complex key.
Fill the disk with zeros.
Erase it again, without encryption or with a different key.

Options to fill with zeros

If it is available, use mkfile, otherwise use dd...

mkfile SIZE FILE
Example: mkfile 200G File1
dd if=/dev/zero of=FILE bs=BLOCKSIZE count=BLOCKS
Example: dd if=/dev/zero of=File1 bs=1024 count=1000000