Originally Posted by funkypunkypinkypow
What is the difference between dd if=/dev/null of=/dev/HDD or HDD parititon and dd if=/dev/zero of=/dev/HDD or HDD parititon?
briefly put, /dev/null yields no input (just an eof() condition), while /dev/zero produces an endless stream of NUL bytes as input. When used as output, both ignore any data being sent to them.
So if you use /dev/null as an input for dd, the operation will stop before it has really started, effectively leaving the hard disk unchanged, while /dev/zero being used as an input really results in your hard disk being erased sector by sector, byte by byte.
Honestly, I also used to mix up /dev/null and /dev/zero for quite some time.
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