creating a bootable usb drive from a .img file on OSX
From https://help.ubuntu.com/community/Installation/FromImgFiles:
- Download the desired .img file
- Open a Terminal (under Utilities)
- Run diskutil list to get the current list of devices
- Insert your flash media
- Run diskutil list again and determine the device node assigned to your flash media (e.g. /dev/disk2)
- Run diskutil unmountDisk /dev/diskN (replace N with the disk number from the last command; in the previous example, N would be 2)
- Execute sudo dd if=/path/to/downloaded.img of=/dev/diskN bs=1m (replace /path/to/downloaded.img with the path where the image file is located; for example, ./ubuntu.img). If you see the error dd: Invalid number `1m', you are using GNU dd. Use the same command but replace bs=1m with bs=1M.
- Run diskutil eject /dev/diskN and remove your flash media when the command completes
