How to make a Ubuntu boot usb in OSX (don’t use the UNetbootin USB installer)

I had a lot of trouble making an Ubuntu boot USB drive from OSX. The instructions on don’t work in general. I think there are two reasons:

  • The program doesn’t reformat the USB drive

  • If there are existing files on the USB from say a 32-bit Ubuntu and you create a 64-bit usb, UNetbootin doesn’t overwrite all the necessary files. In this case the installation goes smoothly but when you reboot the installed system, you get a “No working init” error.

The best way to do it is:

  1. Insert your usb and determine device using
    diskutil list

In my case it was /dev/disk2

  1. Unmount using
    diskutil unmountDisk /dev/disk2
  1.  (BE CAREFUL YOU GET THE DISK NUMBER RIGHT IN THIS STEP) Assuming the ubuntu iso file is XX.iso, write to usb using
    sudo dd if=XX.iso of=/dev/rdisk2 bs=4m