Creating a bootable USB drive on Mac OSX

Below are the steps needed to create a bootable USB device:

1.Download/create the ISO file you want to load in the USB

Once you have the ISO then it is time to convert to an image file:

hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/ubuntu.iso

Breaking down the command:
hdiutil description:

hdiutil uses the DiskImages framework to manipulate disk images. Common verbs include attach, detach,
verify, create, convert, compact, and burn.

The -fomat argument specifies the format of the image you want to create, by default UDZO is used.
UDZO stands for “UDIF zlib-compressed” image and UDIF is an acronym for Universal Disk Image
More info about UDIF
However, instead of UDZO we’ll use the format UDRW (UDIF read/write image)
More info on disk image formats

The argument -o defines where the image will be savedScreen Shot 2013-01-21 at 10.19.07 AM

2. Copy the image to the USB device

Before copying the image, find where the usb device is located by running:

diskutil list

diskutil description:

diskutil manipulates the structure of local disks. It provides information about, and allows the
administration of, the partitioning schemes, layouts, and formats of disks. This includes hard disks,
solid state disks, optical discs, CoreStorage volumes, and AppleRAID sets. It generally manipulates
whole volumes instead of individual files and directories.

Once you find where the device is located run:

diskutil unmountDisk /dev/diskN (N is the number of the device)

Now that the image is created and the usb device is in place it is time to copy the image to the usb:

sudo dd if=/path/to/image.img of=/dev/diskN bs=1m

The dd command will copy everything from the standard input to standard output

The if argument is to specify the input
The of the output
And the bs the block size of the data that will be copied, in this case it’s set to 1M, or 1024 bytes
Screen Shot 2013-01-21 at 11.35.02 AM

Once the dd command is finished, a popup window might show up:
Screen Shot 2013-01-21 at 11.34.51 AM

Just to make sure check if the usb was ejected:

diskutil list

Find where the device is located and if it is still there:

diskutil eject /dev/diskN

That’s all, you should have a bootable USB device by now :)

Install Ubuntu using USB drive
hdiutil man page
diskutil man page
dd man page
dd command info
Disk Images

VirtualBox and USB devices, vboxusers.

By default when installing VirtualBox on Ubuntu, you won’t be able to access USB devices in the VM.

To get around that problem is very simple, below are listed the steps needed to get access to USB devices in the VM.

First, make sure you have the latest version of the software:
Download VirtualBox

You also need to install the extension pack:
Get Extension Pack

and the Guest Additions:

Guest Additions Manual

After installing all the extra dependencies, it is time to enable USB access to the VM.


Right click on the VM and select settings:

You will get this message:

Failed to access the USB subsystem*

VirtualBox is not currently allowed to access USB devices. You can change this by adding your user to the ‘vboxusers’ group. Please see the user manual for a more detailed explanation.

It tells that you need to add your user to the vboxusers group.


There are two ways to add users to groups in Ubuntu.
Via the GUI

If you want something faster, it is also possible to add a user to a group via the command line:

After adding the user to the vboxusers group you need to restart Ubuntu.


Now after adding the user to the vboxusers group, it is time to select which USB device you want to mount in the VM


Access USB devices in the VM

More Info: