diskutil list
select your disk
unmount your selected disk
diskutil unmount /dev/disk2s1
dd if=generic-sdcard-v1.3.img of=/dev/disk2 bs=100m
diskutil eject /dev/disk2
Your disk is written with an image.
diskutil list
select your disk
unmount your selected disk
diskutil unmount /dev/disk2s1
dd if=generic-sdcard-v1.3.img of=/dev/disk2 bs=100m
diskutil eject /dev/disk2
Your disk is written with an image.