Why is the error, dd: /dev/rdisk1bs=1m: Operation not supported, popping up while trying to instal ubuntu on usb?

Question

I am trying to install ubuntu onto my flash drive using the instructions from this website: http://www.ubuntu.com/download/help/create-a-usb-stick-on-mac-osx.

After step 8, the terminal asks for my password, which it accepts and then pops up with this error message:

dd: /dev/rdisk1bs=1m: Operation not supported.

I have also tried making the last m in that statement capital and then the system does not ask me for my password but the error message still pops up. What is happening and why?

Solution 1

If you clicked the little eject icon in the Finder, this will unmount and eject the usb drive, which will give the error you saw. You want to umount only.

Unmounting can be done in Apple's Disk Utility using the Unmount button (in toolbar next to Eject), or it can be done as Marcel answers below from the commandline.

sudo diskutil unmountDisk /dev/diskN

Solution 2

If the disk is still mounted, you'll get a 'resource busy' error. If it's been ejected, you'll get the 'Operation not supported' error. You need to go into disk utility and UNMOUNT the partitions on the drive but do not EJECT the destination drive. Hope this helps as it can get kinda frustrating and the errors aren't always particularly helpful.

Solution 3

If the above does not help (as it did for me), try

sudo diskutil umountDisk /dev/diskN

That did the trick for me.

Solution 4

I've also had a similar problem while using the correct syntax (i.e. dd bs=1m if=source.img of=/dev/rdisk1).

A reboot seemed to fix my issue, despite several attempts with a command that had worked previously while restoring a different image.

Hope this helps!

Solution 5

of=/dev/rdiskN bs=1m

I didnt realize my first time that the N is still a variable for the disk number you found when running diskutil list

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Comments

[Samik]

There should be a space between /dev/rdisk1 and bs. If that's not the typo you've done while issuing that dd but only here, you can edit your question so that no confusion arise.

[Admin]

Hmm... Try to erase all data on USB(via terminal or via Disk Utility)

[WA2050]

Welcome to AskUbuntu. It would be helpful to OP if you can explain your answer in more details.

[Joren]

Some explanation?

[user391339]

Unmount failed for /dev/rdisk3

[Yokiie]

You rox!! Thank you! I was having difficulties to find the solution, thank you very much! :)

[Jacksonkr]

I had to use sudo diskutil unmountDisk /dev/diskNsX

[DimP]

Well that's what @DreadPirate suggested and it's fine. All I am saying is if that does not work, try my suggestion. It works on my machine.

[sivann]

this is correct. Using the "umount" command also ejects the disk (!)

[Sridhar Sarnobat]

Strange, even for me Mac OS insisted on bs=512k. Thank you.