I just wrote this up for a friend, I figured why not add it to my blog so that we can add it to the list of other how-tos on the Internet.

This was done with MacOS 10.11 and is all CLI-based; more likely to be durable into the future that way.

Because Markdown is good in some ways and incredibly annoying in others (“If you do use lazy list numbering, however, you should still start the list with the number 1. At some point in the future, Markdown may support starting ordered lists at an arbitrary number.”) y’all are getting a bunch of bullet points instead of numbered steps. Sorry, this one isn’t my fault.

  • I downloaded http://releases.ubuntu.com/14.04/ubuntu-14.04.5-server-amd64.iso.torrent via Transmission (bittorrent in datacenter with multiple gig links to the internet = awesome)
  • scped it down to laptop
  • In a terminal window: “hdiutil convert ubuntu-14.04.5-server-amd64.iso -format UDRW -o ubuntu-14.04.5-server-amd64.img” - note that this creates a .img.dmg file as output <cough, thanks Apple>

Do note that this doesn’t change the file size, but it does change the checksum:

maddog:Downloads rs$ ls -l ubuntu-14.04.5*
-rw-r--r--  1 rs  staff  649068544 Mar  8 08:34 ubuntu-14.04.5-server-amd64.img.dmg
-rw-r--r--  1 rs  staff  649068544 Mar  8 08:31 ubuntu-14.04.5-server-amd64.iso
maddog:Downloads rs$ md5 !$
md5 ubuntu-14.04.5*
MD5 (ubuntu-14.04.5-server-amd64.img.dmg) = c73f8664f3c37fcafd89c0d12b25d0c7
MD5 (ubuntu-14.04.5-server-amd64.iso) = dd54dc8cfc2a655053d19813c2f9aa9f
maddog:Downloads rs$ 
  • Again in a terminal window, “diskutil list” - find your usb drive; in my case disk2
  • diskutil unmountdisk /dev/disk2
  • once more in a terminal window: “sudo time dd if=ubuntu-14.04.5-server-amd64.img.dmg of=/dev/rdisk2 bs=512k”

This took about two minutes to run for me but is more dependent on your thumb drive and its characteristics than anything else. When it’s done you’ll get a pop-up saying that the disk was not readable by your mac (which is true; it’s a linux fs, not mac)

  • You’re done. You now have an install thumb drive.

This is known to work fine with ubuntu and some other stuff but has specifically given me problems with RHEL/CentOS, something about their grub being too stupid to realize where it’s being loaded from and having “cd0” baked into it, so it boots partway and then loses its cookies. so this is not a universal way to convert an iso into a thumb drive image.