Ubuntu Wiki

About .img files

.img files are disk images, including partition arrrangements, boot sectors, and other details. They may be used as virtual disks (RAW format) in virtual environments (e.g. kvm), or written to removable media (USB drives, flash memory cards, etc.) for use as an installation medium.

Writing .img files to a target

Before writing an image to a target, it is highly recommended that you verify the md5sum (hash) of the .img file. For instructions, please see HowToMD5SUM. For the current list of Official Ubuntu MD5 hashes, see the MD5SUMS file for the release you're using under http://releases.ubuntu.com (and optionally the PGP signatures in the MD5SUMS.gpg file, or see UbuntuHashes. This ensures that the file was not damaged during the download process and is 100% intact.

There are many ways to write the .img files to a target device. Some common methods include:

Ubuntu GUI

1. Download the desired .img file
2. Install the usb-imagewriter package

   • If your release does not include this, Download it from a PPA.

3. Open Applications -> Accessories -> Image Writer

4. Attach your target device
5. Select the downloaded file and target device, and click "Write to Device"
6. Remove your device when the operation is complete

Ubuntu CLI

1. Download the desired .img file
2. Open a terminal and attach your target device

3. Look at the output of dmesg | tail -20 to determine the device node assigned to your device (e.g. /dev/sdb)

4. Run sudo umount /dev/device/node

5. Run sudo dd if=/path/to/downloaded.img of=/dev/device/node bs=1M

6. Remove your device when the command completes

Windows GUI

1. Download the desired .img file

2. Download Disk Imager from https://launchpad.net/win32-image-writer/+download

3. Attach your target device
4. Note the drive letter assigned to your device
5. Start Disk Imager
6. Select the downloaded file and target device, and click "Write"
7. Remove your device when the operation is complete

Windows CLI

1. Download the desired .img file

2. Download flashnul from http://shounen.ru/soft/flashnul

3. Attach your target device

4. Run flashnul -p

5. Note the physical device number for the target device

6. Run flashnul <number obtained in prior step> -L \path\to\downloaded.img

7. Answer "yes" if the selected destination device is correct
8. Remove your device when the command completes

Mac OS X CLI

1. Download the desired .img file
2. Open a Terminal (under Utilities)

3. Run diskutil list to get the current list of devices

4. Attach your target device

5. Run diskutil list again and determine your device node (e.g. /dev/disk2)

6. Run diskutil unmountDisk /dev/device/node

7. Execute sudo dd if=/path/to/downloaded.img of=/dev/device/node bs=1M

8. Remove your device when the command completes

Performing the Install

Once your target device has been written, boot your computer from this device, and proceed with the instructions for the type of install you selected (Live image, Alternate, etc.).