Re: dd if=/dev/rdisk12 of=/dev/zero (OT, since macOS)
Date: Sat, 01 Nov 2025 15:43:23 UTC
try using /dev/null as your output. instead of /dev/zero On Sat, 1 Nov 2025, 15:08 Christoph Kukulies, <kuku@kukulies.org> wrote: > > 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> > 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 >> >> >> >> Am 01.11.2025 um 15:32 schrieb Odhiambo Washington <odhiambo@gmail.com>: >> >> >> >> On Sat, Nov 1, 2025 at 5:10 PM Christoph Kukulies <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/ > > >