UNetbootin on Mac OS X # fix to create a BackTrack5 USB stick to boot elsewhere

Christopher Friedt writes:

Just in case anyone wants to use UNetbootin to create e.g. an Ubuntu Live USB device and it isn’t working, there are two key steps that are not performed by the UNetbootin binary for OS X.

After downloading the ISO, use Disk Utility to partition your USB device. Ensure that you’ve selected Options -> MBR . After formatting the disk…

1) Ensure that you’ve marked the partition active

fdisk -e /dev/rdisk1

f 1



2) Download syslinux and write the critical mbr binary your device.

dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/rdisk1

After that, just use UNetbootin as usual.

I got away with just doing the fdisk to activate the partition, otherwise it just comes up with “Missing Operating System“.

This worked for BackTrack5 r3.

via The Perpetual Notion: UNetbootin on Mac OS X.

26 Replies to “UNetbootin on Mac OS X # fix to create a BackTrack5 USB stick to boot elsewhere”

  1. Useful to know – I’ve also had a look at BackTrack.

    Last I knew, though, you couldn’t boot a Mac from USB. Is this purely about creating bootable sticks on a Mac, for use on some other box?

  2. I am getting the following messages below.

    UTIs-MacBook-Pro:~ UTI$ fdisk -e /dev/rdisk1s1
    fdisk: /dev/rdisk1s1: Permission denied
    UTIs-MacBook-Pro:~ UTI$ sudo -s
    bash-3.2# fdisk -e /dev/rdisk1s1
    fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory
    Enter ‘help’ for information
    fdisk: 1> f 1s1
    Partition 1 marked active.
    fdisk:*1> write
    Device could not be accessed exclusively.
    A reboot will be needed for changes to take effect. OK? [n] y
    Writing MBR at offset 0.
    fdisk: 1> dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/rdisk1s1
    Invalid command ‘dd’. Try ‘help’.
    fdisk: 1> exit
    bash-3.2# dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/rdisk1s1
    dd: mbr.bin: No such file or directory

    Kindly tell me if i am doing something wrong …. Thankx

  3. @XaRuS
    First you must cd to the mgr directory: Downloads/syslinux-5/mbr
    Then execute:
    diskutil unmountDisk /dev/disk1
    sudo fdisk -e /dev/rdisk1
    Type your password.
    fdisk: 1> f 1
    fdisk:*1> write
    fdisk: 1> exit
    dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/rdisk1

    1. Kindly write out instructions to create Backtrack 5 R3 a bootable usb for Mac OS. I will appreciate it

  4. dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/rdisk1s1

    dd: mbr.bin: No such file or directory

    please hep

  5. @Don
    1. Download backtrack 5 R3 iso
    2. Open terminal
    3. Execute diskutil list
    Output should be something like: diskutil list
    0: GUID_partition_scheme *500.3 GB disk0
    1: EFI 209.7 MB disk0s1
    2: Apple_HFS Macintosh HD 419.0 GB disk0s2
    3: Apple_Boot Recovery HD 650.0 MB disk0s3
    0: FDisk_partition_scheme *7.8 GB disk1
    1: DOS_FAT_32 U 7.8 GB disk1s1

    4. Identify your USB, mine is /dev/disk1
    5. Execute sudo diskutil unmountDisk /dev/disk1
    6. Execute sudo fdisk -e /dev/disk1 , then f 1, then write, then exit.
    7. Sudo diskutil unmountDisk /dev/disk1
    8. Download syslinux from http://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-5.00.zip and unzip it by double clicking.
    9. Navigate to the syslinux/mbr folder using terminal:
    cd /Users/yourusername/Downloads/syslinux-5/mbr
    10. sudo dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/disk1
    11. Open Unetbootin and enter your password, select “disk image”, click on the three dots, select the previously downloaded backtrack 5 R3 .iso and click open.
    12. Enter the amount of persistence space that you want for your usb. The persistence will be used to store changes after reboot. You can make it as large as you like because unetbootin will round it down to fit on your usb.
    13. Select your usb drive in the box, probably /dev/disk1s1 and click ok.
    14. Wait for unetbootin to finish. It might take a long time and seem like it’s frozen but it’s not.
    15. Exit unetbootin and shutdown your mac.
    16. Power on your mac and as soon as the screen turns white, start holding the alt/option key.
    17. Choose your usb. (A yellow usb or hard drive icon on the right) There might be two, if one doesn’t work, try the other.

    This works fine as long as your mac doesn’t have usb 3.
    Remember to replace /dev/disk1 with the number you get but make sure it’s not disk0.

    1. Hello good solution but I have 2 questions I see in the main post:
      fdisk -e /dev/rdisk1
      and you have here:
      fdisk -e /dev/disk1
      without the “r” on disk1 what is the diiference is not supposed to be rdisk1 instead disk1 only?
      My other question I have a retina macbook pro I tried to burn with unetbootin with windows and YUMI and say Unable to find a medium containing live file system after the backtrack choice menu I’m not tried yet this method but I’ll try but how you know the retina has 2 USB 3.0 ports for sure I don’t have USB 2.0 what you suggest to make run in retina macbook?
      Thank you

      1. Carlos,
        Unfortunately backtrack does not currently work on laptops that only have USB 3, including the retina MacBook Pro. It’s up to the backtrack developers to update their OS for USB 3 and as far as I can see, this won’t be happening anytime soon. Your best option is to use another OS such as BackBox. BackBox works well on my retina MacBook Pro and comes with many of the same tools backtrack has.

        1. Ok thank you I’ll try BackBox and I’ll try to test backtrack in a mini fire wire external disk maybe works too, there are in Amazon some cases mini and pretty with firewire that fits in the palm of the hand.
          Thank you

    2. @4help


      I followed exactly what you wrote and all worked fine, but when I restart my computer to boot from my usb drive (holding alt button pressed), it doesn’t appear that can boot from it !! I have USB 2.0 port.

      Please Help

  6. Holy crap you guys saved my day. The error was a non issue on linux mint for “fdisk -e /dev/disk1” as mint is an EFI install. However, the “f 1” is why unetbootin was not working on my pc machine where the usb was created on my mac.

  7. As soon is a I follow all the steps, my usb get brocken and MacOS X does not let me mount it again. It is a shame…

    1. same for me..
      I do the fdisk and dd without trouble but I can’t mount the disk afterwards and can’t use Unetbootin.. it wont let me click “OK” – it clicks but nothing happens.

  8. Computer:recovery user$ sudo fdisk -e /dev/disk1
    fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory

  9. There’s no need to install syslinux as the “mbr.bin” file can be found inside UNetbootin: unetbootin.app/Contents/Resources/mbr.bin

  10. i got this error:

    sudo fdisk -e /dev/disk2
    fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory

  11. I am wondering you guys have a running Backtrack from USB drive…I followed your instructions point for point many times, tried different USB drives and it is still not working. And without another Bootloader it shouldn’t work for you guys either, because Macs usually can’t boot from any other partition scheme then GUID, since Apple decided to switch to INTEL. So where is my problem….why is it working for you guys and not for me. After copying the files via unetbootin, it tells me, it never would boot from a Mac. And that’s how it is. I really would appreciate every help, cause I always wanted to have a Backtrack booting from USB on my Mac, since I pulled out the SuperDrive. Thanks in advance…Cheers, Fab

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