Command line

If you are comfortable with the command line, you can image a card without any additional software. Run:

diskutil list

Identify the disk (not partition) of your SD card e.g. disk4 (not disk4s1):

diskutil unmountDisk /dev/<disk# from diskutil>
e.g. diskutil unmountDisk /dev/disk4
sudo dd bs=1m if=image.img of=/dev/<disk# from diskutil>
e.g. sudo dd bs=1m if=2015-02-16-raspbian-wheezy.img of=/dev/disk4

This may result in an dd: invalid number ‚1m‘ error if you have GNU coreutils installed. In that case you need to use 1M:

sudo dd bs=1M if=image.img of=/dev/<disk# from diskutil>

This will take a few minutes.

Alternative method

Note: Some users have reported issues with using Mac OS X to create SD cards. These commands and actions need to be performed from an account that has administrator privileges.

From the terminal run

df -h.

Connect the SD card reader with the SD card inside. Run

df -h

again and look for the new device that wasn’t listed last time. Record the device name of the filesystem’s partition, for example /dev/disk3s1.

Unmount the partition so that you will be allowed to overwrite the disk:

sudo diskutil unmount /dev/disk3s1

(or open Disk Utility and unmount the partition of the SD card (do not eject it, or you will have to reconnect it)
Using the device name of the partition, work out the raw device name for the entire disk by omitting the final „s1“ and replacing „disk“ with „rdisk“. This is very important as you will lose all data on the hard drive if you provide the wrong device name. Make sure the device name is the name of the whole SD card as described above, not just a partition of it (for example, rdisk3, not rdisk3s1). Similarly, you might have another SD drive name/number like rdisk2 or rdisk4; you can check again by using the df -h command both before and after you insert your SD card reader into your Mac. For example, /dev/disk3s1 becomes /dev/rdisk3.

In the terminal, write the image to the card with this command, using the raw disk device name from above. Read the above step carefully to be sure you use the correct rdisk number here:

sudo dd bs=1m if=2015-02-16-raspbian-wheezy.img of=/dev/rdisk3

If the above command reports an error (dd: bs: illegal numeric value), please change bs=1m to bs=1M.

If the above command reports an error dd: /dev/rdisk3: Permission denied then that is because the partition table of the SD card is being protected against being overwritten by MacOS. Erase the SD card’s partition table using this command:

sudo diskutil partitionDisk /dev/disk3 1 MBR „Free Space“ „%noformat%“ 100%

That command will also set the permissions on the device to allow writing. Now try the dd command again.

Note that dd will not feedback any information until there is an error or it is finished; information will be shown and the disk will re-mount when complete. However if you wish to view the progress you can use ‚ctrl-T‘; this generates SIGINFO, the status argument of your tty, and will display information on the process.

After the dd command finishes, eject the card:

sudo diskutil eject /dev/rdisk3

(or: open Disk Utility and eject the SD card)