This part can take some time but when you are back on the command propmt, the USB device should be bootable. Installing OS X From a USB Drive Select the Erase tab on the right and then set Format to Mac OS Extended (Journaled). Finally, copy the image to the USB device. If you have multiple devices attached, it may be a different number so make sure you check this part. Note the first part “ /dev/disk1“, this is the USB device that we need to unmount as can be seen from the size. You need to find the section that looks like this: The first job is to identify and unmount the USB device. Hdiutil convert -format UDRW -o centosdvd.img CentOS-7.0-1406-x86_64-DVD.isoģ. You will need to ajdust the filename if you downloaded something other than the DVD iso. The universal Mac installer installs RoboForm along with extensions for. In terminal, navigate to the directory where your CentOS download is saved (“Downloads” in my case).Ģ. This has only been tested on the CentOS 7 download but it should work for any bootable ISO.ġ. When you have downloaded the CentOS ISO image that you’d like to run from USB, there are a few simple commands to run from the terminal so that you can create a bootable USB key.