Re: dd if=/dev/rdisk12 of=/dev/zero (OT, since macOS)
Date: Sat, 01 Nov 2025 15:08:20 UTC
No, I don't want to use diskutil. I wanted to know why my dd command returns "Invalid argument". Yes, I know it's OT, sorry for that. The suspicion comes up that I'm fallen victim a fake. So I anted to physically read the device once. A program like diskutil or system information USB section only transports the faked information. Is "Invalid argument" already a consequence of the drive being a fake? -- Christoph > Am 01.11.2025 um 16:00 schrieb paul beard <paulbeard@gmail.com>: > > Ah. So you want to verify what 'diskutil info rdisk12' returns? > > On Sat, Nov 1, 2025 at 7:39 AM Christoph Kukulies <kuku@kukulies.org <mailto:kuku@kukulies.org>> wrote: >> No no, direction is intentionally read. I just want to read the disk once to get the exact count of bytes and see its integrity. >> >> >> >> >> Christoph Kukulies >> kuku@kukulies.org <mailto:kuku@kukulies.org> >> >> >> >>> Am 01.11.2025 um 15:32 schrieb Odhiambo Washington <odhiambo@gmail.com <mailto:odhiambo@gmail.com>>: >>> >>> >>> >>> On Sat, Nov 1, 2025 at 5:10 PM Christoph Kukulies <kuku@kukulies.org <mailto:kuku@kukulies.org>> wrote: >>>> Hi co-readers, >>>> >>>> excuse me for coming up with a non FreeBSD question but I'm sure many "also macOS" users are here. >>>> I got an SSD external drive today from China. It's supposed to have 10TB and has the name "SEAGATE" engraved on the cover which I haven't opened >>>> yet, also because it's clipped together - no screws. >>>> >>>> Anyway, I tried >>>> >>>> >>>> # dd if=/dev/rdisk12 of=/dev/zero >>>> >>>> on it (in a macOS terminal window. >>>> >>>> I'm getting >>>> >>>> $ sudo dd if=/dev/rdisk12 of=/dev/zero bs=512 >>>> Password: >>>> dd: /dev/rdisk12: Invalid argument >>>> 0+0 records in >>>> 0+0 records out >>>> 0 bytes transferred in 0.000036 secs (0 bytes/sec) >>>> $ >>>> >>>> also without the bs=512 not any better. >>>> >>>> An ideas what might be wrong? >>> >>> You want to wipe the disk, right? So, you write zeros to the raw device, not the other way round. >>> So it should be something like this: >>> >>> dd if=/dev/zero of=/dev/rdisk12 bs=16M count=1000 status=progress >>> >>> >>> >>> -- >>> Best regards, >>> Odhiambo WASHINGTON, >>> Nairobi,KE >>> +254 7 3200 0004/+254 7 2274 3223 >>> In an Internet failure case, the #1 suspect is a constant: DNS. >>> "Oh, the cruft.", egrep -v '^$|^.*#' ¯\_(ツ)_/¯ :-) >>> [How to ask smart questions: http://www.catb.org/~esr/faqs/smart-questions.html] >> > > > > -- > Paul Beard / www.paulbeard.org/ <http://www.paulbeard.org/>