I have a 32GB USB drive with 2 partitions,

Partition 1: FAT32 used as storage

Partition 2: ext4 intended to be a bootable live Ubuntu 15.04.

How can I install the Ubuntu ISO file to the ext4 partition on the USB drive and make it bootable?

I tried booting DamnSmallLinux and DSL-N from another 512MB USB drive I have but couldn't find how to make this work.

I'm running Windows 7 on desktop PC and OS X Yosemite 10.10.4 on laptop.

  • I'm a bit confused... Do you want to install Ubuntu on USB or just write Ubuntu ISO on USB (create bootable installation usb)?
    – sn4il
    Aug 6, 2015 at 11:42
  • I want to install Ubuntu on USB ext4 partition, not just copy the ISO file. Since Windows can't see more than the first partition on the USB drive can't get this to work with Unetbootin
    – fulanito
    Aug 6, 2015 at 11:46

2 Answers 2


Okay, if I get you right dd is what you need (comes with OS X). You can create bootable USB with the following command:

dd if=/path/to/your/ubuntu.iso of=/dev/xxx bs=4M

(Make sure you saved all necessary data from USB)

Replace xxx in /dev/xxx with your USB device. You can list devices with diskutil list command to find out which one is your USB.

After following this steps you will get bootable USB with Ubuntu and some unallocated free space. So you will be able to boot from it and create some additional partitions on it with GParted.

If you want to install Ubuntu on your USB you should create bootable USB first anyway. Then you can boot from it and install Ubuntu on another USB drive following any Ubuntu installation tutorial on youtube.

  • I'll try this when I'm home, but without any further software OS X is not able to deal with ext4 file systems. But I don't mind either having both partitions as FAT32
    – fulanito
    Aug 6, 2015 at 12:23
  • 1
    @fulanito, dd doesn't need OS X to deal with Ext4. I have managed to create bootable Ubuntu USB on Windows with this utility. It doesn't come with Windows by default but you can get it with Cygwin.
    – sn4il
    Aug 6, 2015 at 12:30
  • With Cygwin I used dd if=/cygdrive/c/Users/path/to/ubuntu.iso of=/dev/sdb bs=4M and could successfully boot Ubuntu from the 32GB USB drive. I tryed partitioning with GParted both from this Ubuntu drive and from the 512MB USB drive where I installed GParted live, but I can't create a partition on the unallocated space because it is not possible to create more than 1 primary partition
    – fulanito
    Aug 6, 2015 at 15:37
  • I used cat /proc/partitions to figure out what /dev/sdx device my USB drive was
    – fulanito
    Aug 6, 2015 at 15:43
  • 1
    GParted reports The driver descriptor says the physical block size is 2048 bytes, but Linux says it is 512 bytes If I ignore it GParted shows following partitions: Imgur
    – fulanito
    Aug 7, 2015 at 5:26

Use Rufus to make an Ubuntu bootable (say) on an 8GB USB drive, from your downloaded disk image (iso) on your hard drive. Then use this to install Ubuntu on your 32GB USB, which you would then set as first boot in the boot sequence in your BIOS/UEFi.

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