Bootable Windows 7 USB Drive via LINUX

Windows-USB-on-Linux.md

PROBLEM: ALL MY WINDOWS IMAGES ARE ON MY LINUX WORKSTATION AND I NEED TO BOOT WINDOWS OFF A USB DRIVE.

Historically, I've used Windows 7 USB/DVD Download tool on a Windows guest OS in VirtualBox to get this done. Well after doing the research and several stick formats later: I've pieced together a better recipe.

Some other solutions/tutorials have some shortcomings. WinUSB is too complicated and doesn't work with certain versions of GRUB. This post comes very close but assumes the drive has a Windows 7 bootloader already.

Make new partition table

Give the USB device one primary partition. This is what I did, other partitioning schemes may work. I'm using fdisk.

Set partition type to 7 (Windows/NTFS)

Use the t option in fdisk

Flag the partition as bootable

Use the a option in fdisk

Format the partition as NTFS

mkfs.ntfs -f /dev/sdx1

Install the NTFS bootloader

Use ms-sys

ms-sys -7 /dev/sdx

ms-sys seems to provides some alternative options for Vista. I have not tested this recipe with Windows 8.

Copy files from the windows image to the NTFS partition

mount WinIMG.iso /path/to/WinIMG -o loop

cp -avr /path/to/WinIMG/* /path/to/usb

Unmount and boot

Get that USB drive out of there and try to boot!

Other notes

If you don't have a USB drive that's large enough, you can plug in the hard drive you're going to install to and use that instead. It works pretty well.