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 saved
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
Once the dd command is finished, a popup window might show up:
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 🙂
Links:
Install Ubuntu using USB drive
hdiutil man page
diskutil man page
dd man page
dd command info
Disk Images
Seneca-CD Research Project 
Howdy! I know this is somewhat off-topic however I needed to ask.
Does running a well-established blog like yours take a massive amount work?
I am completely new to operating a blog but I do write in
my diary on a daily basis. I’d like to start a blog so I will be able to share my personal experience and views online. Please let me know if you have any recommendations or tips for brand new aspiring blog owners. Appreciate it!
The SenecaCD blog is aggregating both mine and Kieran’s posts documenting the work we did in a project at Seneca’s CDOT http://zenit.senecac.on.ca/wiki/index.php/Main_Page
The one thing I would say to you is to start blogging, the hardest part is to actually sit down and write.
Wordpress provides a nice free service to host your blog, it is a good starting point that allows you to focus on the blog content instead of setting up the infrastructure around it.
But the key point is to fight resistance, commit yourself to writting a post a week and do it constantly.
Hit me back with your blog url when you get started.
Good luck!