MacOS High Sierra: Create Windows bootable Usb

This adds on to Django's answer, pointing out how to allow the option for revealing "Create a Windows 7 Installation Disk" in Boot Camp Assistant.

I checked the Bootcamp documentation and it says I may have the option to "create a windows installation disk" but I don't have that option (unsure why?)

Because you cannot see this option, it is most likely because your computer is not supported in Boot Camp Assistant.app's Info.plist. However, that can be quickly changed.

1. Open a new Terminal window and run sudo nano /Applications/Utilities/Boot\ Camp\ Assistant.app/Contents/Info.plist

2. Type in your password.

3. Move with the arrow keys down to the bottom where it says:

(I meant to start with " (<) key (>) USBBootSupportedModels (<) /key (/>), but I don't know how to ignore HTML markup here. _{If a moderator or someone who knew how could change this, that would be great.}

<array>
<string>IM130</string>
<string>MM50</string>
<string>MP60</string>
<string>MB80</string>
<string>MBP90</string>
<string>MBA40</string>
</array>

Check for your computer model number in  > About this Mac... > More info... > System Report... in Hardware Overview under Model Identifier. It should be something like

    Model Identifier: iMac10,1

iMac = IM, Mac mini = MM...and your MacBook Air would be MBA. Now, simply take MBA and add it to the numbers after (MacBook Air3,2 to MBA32) without the comma.

Go back to your Terminal prompt and remove the current string part with MBA (you may want to make a note of this somewhere, in case you decide to revert later). Replace it with an identical one that says:

... <string>MBA32</string> ...

(Without the ellipses)

Now save the file by typing Control-O and confirming the WriteOut by pressing the return key (make sure Wrote xx lines appears). Quit and re-open Boot Camp Assistant, and the option should be available!

At this point, you can select your .iso image, as usual (given that you've already converted the .img)

Here is how to burn a bootable USB stick (taken from the Ubuntu website):

1. Open the Terminal (in /Applications/Utilities/ or query Terminal in Spotlight).
2. Convert the .iso file to .img using the convert option of hdiutil e.g., hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/windows.iso Note: OS X tends to put the .dmg ending on the output file automatically.
3. Run diskutil list to get the current list of devices.
4. Insert your flash media.
5. Run diskutil list again and determine the new device node assigned to your flash media (e.g. /dev/disk2).
6. Run diskutil unmountDisk /dev/diskN (replace N with the disk number from the last command; in the previous example, N would be 2).
7. Execute sudo dd if=/path/to/downloaded.img of=/dev/rdiskN bs=1m (replace /path/to/downloaded.img with the path where the image file is located; for example, ./windows.img or ./ubuntu.dmg). Using /dev/rdisk instead of /dev/disk may be faster. If you see the error dd: Invalid number '1m', you are using GNU dd. Use the same command but replace bs=1m with bs=1M. If you see the error dd: /dev/diskN: Resource busy, make sure the disk is not in use. Start the 'Disk Utility.app' and unmount (don't eject) the drive.
8. Run diskutil eject /dev/diskN and remove your flash media when the command completes.
9. Restart your Mac and press alt/option key while the Mac is restarting to choose the USB stick.