I downloaded the ISO for Debian's net installation to a computer running OS X. I want to put the data from the ISO onto a USB, so that I can install Debian on another laptop (not an Apple laptop). That laptop currently has no system installed, so I must prepare the USB drive on the OS X computer.

First, I tried installing UNetbootin on the OS X computer. When this bootable USB didn't boot, I found a bug report here suggesting that, although UNetbootin lists a version for OS X, it is actually not able to create bootable USBs.

Next, I tried the instructions at DebianEeePC How-to:

dd if=debian-7.*-netinst.iso of=/dev/disk1s1

This took about 10 minutes, reported no errors, but the USB still is unbootable.

  • In the past, USBs created with UNetbootin on Windows, and using the dd method in Linux worked successfully, but at this present time, only have OS X available to me.

How can I create a bootable Linux installation USB from an ISO in OS X?

4 Answers 4


You have to Convert the ISO to UDRW format using:

hdiutil convert -format UDRW -o destination_file.img source_file.iso

for Further steps and reference click this link,

go with the steps: Create bootable USB stick from ISO in Mac OS X

  • Is the resulting image bootable on non-Apple hardware? Documentation on hdiutil says UDRW is a UDIF read/write image format, and wikipedia claims that UDIF is Apple-specific proprietary format.
    – cnst
    Commented Apr 26, 2014 at 16:46
  • I've expanded my comment as above into a separate question: unix.stackexchange.com/questions/126655/…
    – cnst
    Commented Apr 26, 2014 at 16:58
  • I just answered the other question you linked, but for others that can't be bothered to click that far: yes, it is bootable on non-apple hardware; I just tried it. Commented Jan 9, 2015 at 1:04
  • The corresponding Ubuntu instructions: ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx
    – 0 _
    Commented Dec 21, 2015 at 16:58

dd should be done to the device of=/dev/disk1 instead of the partition of=/dev/disk1s1


As the comment above states (from cnst), UDRW appears to be Apple/mac/OSX proprietary. I had to convert to "UDTO - DVD/CD-R master for export" to make the USB bootable on other machines. When dd is finished in this case OSX (Mavericks) complains that it cannot read the disk/USB in this format which kinda confirms it. Also, unetbootin for OSX does not work either.

All of the instructions all over the internet blogsphere and even official linux documentation say to use UDRW and are not clear about specifically creating bootable USB for MAC.

So there are dozens of sites out there with instructions to create bootable linux USB drive on OSX. All I did was replace UDRW with UDTO on the hdiutil command and it worked:

hdiutil convert -format UDTO -o destination_file.img source_file.iso
  • For me, converting to UDRW or UDTO (from ISO) always resulted in the same file (the same as the input ISO, md5's matched). Thankfully for most Linux ISO's they are already enough so this OK. Unfortunately not so much with Windows ISO's though FWIW: superuser.com/q/1063220/39364
    – rogerdpack
    Commented Apr 10, 2016 at 2:46

I would consider https://unetbootin.github.io/ to be a valid answer for people in search for a convenient solution using a GUI. It also takes away the part of downloading the iso, if you like.

Its there for ages and i guess robust enough to be mentioned

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