Writing images to raw disk
In this short tutorial we will write a Raspbian image for a Raspberry Pi to a micro sd-card.
First find out where our target disk is. Insert an (micro) sd-card into the card reader and issue the following command inside the terminal application:
Output should read something like below:
I use a 32Gb card so my card should be /dev/disk1. Your card may have a different name. Note that overwriting the wrong disk may mean you need to reinstall OS X!
Now unmount the sd-card:
diskutil unmountDisk /dev/disk1
It should say now that all volumes on that disk are unmounted successfully. Then it is time to write the image to disk:
sudo dd if=2015-01-31-raspbian.img of=/dev/disk1
You have to use sudo here, because normally mere mortals don't have write access to raw disks. Writing the image takes a few minutes and dd is very uninformative regarding progress so it may seem after a while something is wrong, but you just need patience.