alt Hacker NewsI've seen "dd if=/dev/removable of=/dev/removable" suggested. I don't know if it actually works or if the OS optimizes it to a no-op.
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piyh • today at 6:33 PM
the risk of catastrophic data loss from misuse of `dd` makes my hackles rise just looking at this.
I will never forget when I mixed up `if` and `of` during a routine backup.
`cat /dev/sda > /mnt/myDisk2` is so much safer, explicit, and in unix norms. It's also faster because you don't have to tune block size parameters.
Plus you can also do `pv /dev/sda > /mnt/myDisk2` to get transfer speed details.
Friends don't let friends use `dd` where `cat` can do the same job.
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Certainly the OS can't optimize it to a no-op, since `dd` makes separate read and write syscalls.
I suppose your `dd` implementation itself could do so, but I don't know why it would.