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So far Ubuntu (and derivatives) has been delivering ISO images to be burned onto optical media. Then there's a tool (usb-creator) to "burn" those ISOs onto USB drives. I could be wrong, but I think that nowadays the majority of users don't use optical media to install Ubuntu (as well as other OSs) also because optical drives are not any more standard.

A "USB image" is usually "burnt" with a standard dd which is readily available within whatever OS you already have. While if you are not coming from Ubuntu it's likely your conversion tool is different from Ubuntu's and it won't work flawlessly.

What is the advantage for Ubuntu to keep the ISO instead of a "dd-able" image?

EnzoR
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  • Maybe a duplicate? http://askubuntu.com/questions/150069/why-dd-is-not-a-reliable-command-to-write-bootable-iso-files-to-usb-thumb-drive – sebge23 Jan 29 '16 at 08:01
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    the current iso is dd-able and has been for a couple of years now – mchid Jan 29 '16 at 08:01
  • Of the currently available tools on Windows, Unetbootin and Universal USB Installer have been working flawlessly with Ubuntu images for years now. – muru Jan 29 '16 at 08:28
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    Because ISO images can easily be burned to a CD, DVD, or USB thumb drive, whereas providing a USB drive installation format wouldn't work on a CD/DVD. – dr_ Jan 29 '16 at 09:35

1 Answers1

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The current iso image is ddable and the images have been ddable for quite some time now as far as I know.

sudo dd if=./ubuntu.iso of=/dev/sdx bs=16M

Where ./ubuntu.iso is the path to the actual file and /dev/sdx is the target USB drive.

Alternatively, you can use cat instead of dd which is arguably faster like so:

sudo -i
cat ./ubuntu.iso > /dev/sdx
exit

Again, ./ubuntu.iso represents the full path to the actual iso file and /dev/sdx is the actual USB device.

Even if the image were not ddable, it would simply take a couple of syslinux commands to convert the image to ddable form.

Hypothetically, if the Ubuntu iso images were not ddable, you would just have to run the following commands:

sudo apt-get install syslinux syslinux-utils
isohybrid ./ubuntu.iso --entry 4 --type 0x1c
dd if=./ubuntu.iso of=/dev/sdx bs=16M

Again, where ./ubuntu.iso is the path to the actual iso file and /dev/sdx is the actual USB device.

source

mchid
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    Another nice way of doing it is with sudo -i and pv /path/to/image.iso >/dev/sdX for the fancy progress bar. – kos Jan 29 '16 at 08:37
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    @kos newer versions of dd also have a progress bar but I don't think we have it yet https://wiki.archlinux.org/index.php/core_utilities#dd – mchid Jan 29 '16 at 08:51
  • No, but we should be almost there, on Vivid the latest available version of coreutils is 8.23 and the progress bar for dd has been introduced in coreutils 8.24: http://askubuntu.com/a/715075/380067 – kos Jan 29 '16 at 08:54
  • @mchid I voted to your answer. But ... 1) The link you give is not for Ubuntu but TAILS. 2) The link you provided is available only as an archived page and it's not current. 3) The Official Ubuntu Documentation says otherwise (I linked it in the question). Nonetheless I think you're right, sir. – EnzoR Jan 29 '16 at 10:04
  • It might be relevant to mention that trying to install Ubuntu on the USB media which you just booted the installer from can be tricky. One has to add toram to the boot command line in order to make it work (and that only works if you have at least 2GB of RAM). – kasperd Jan 29 '16 at 12:58
  • @kasperd At that point you may as well mount the ISO in a VM and install to the USB drive from that given you must have had some way of getting the ISO onto the drive in the first place. – JAB Jan 29 '16 at 13:52
  • @JAB There is a couple of reasons your VM approach might not work. First it might be that the copying image to USB device would be done on a machine that does not have sufficient memory to run the VM. It could also be that the exact contents of the final install depends on the hardware you run the installer on. That means the final install on the USB media may end up having drivers for VM rather than drivers for the hardware you intend to use the USB media on in the end. – kasperd Jan 29 '16 at 14:00
  • @kasperd Good points. – JAB Jan 29 '16 at 15:06
  • @Uqbar 1. The link I posted is for instructions on how to make a non dd able iso dd able because the instructions no longer exist, I had to use wayback machine to link the source of my information to give due credit where it is deserved. 2. I did not link to the link because, the current tails iso is dd able just like the current Ubuntu iso and so the current instructions only provide instructions for how to run the dd command I probably should have indicated that or something. – mchid Jan 29 '16 at 16:09
  • @Uqbar the link you posted is not the official ubuntu docs it is for man7.org – mchid Jan 29 '16 at 16:10
  • @Uqbar if you were referring to these instructions: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx I have not tested it, however, I believe dd alone is sufficient. – mchid Jan 29 '16 at 16:12