How to make Windows 7 USB flash install media from Linux?

https://gist.github.com/kuznero/9eb62f6f0612a32d9c4446a4f1f4cf74

• Install ms-sys - if it is not in your repositories, get it here. Or alternatively, make sure lilo is installed (but do not run the liloconfig step on your local box if e.g. Grub is installed there!)
• Check what device your USB media is assigned - here we will assume it is /dev/sdb. Delete all partitions, create a new one taking up all the space, set type to NTFS (7), and remember to set it bootable:

# cfdisk /dev/sdb
or fdisk /dev/sdb (partition type 7, and bootable flag)

• Create an NTFS filesystem (if this step produces error, you may need to reboot):

# mkfs.ntfs -f /dev/sdb1

• Write Windows 7 MBR on the USB stick (also works for windows 8), multiple options here:

# ms-sys -7 /dev/sdb
or (e.g. on newer Ubuntu installs) sudo lilo -M  /dev/sdb mbr (info)
or (if syslinux is installed) sudo dd if=/usr/lib/syslinux/bios/mbr.bin of=/dev/sdb

• Mount ISO and USB media:

# mount -o loop win7.iso /mnt/iso
# mount /dev/sdb1 /mnt/usb

• Copy over all files:

# cp -r /mnt/iso/* /mnt/usb/
or use the standard GUI file-browser of your system

• Call sync to make sure all files are written.

...and you're done.

• After all that, you probably want to back up your USB media for further installations and get rid of the ISO file... Just use dd:

# dd if=/dev/sdb of=/win7.img

and reverse if/of next time you want to put the Windows 7 installer onto USB.

As always, double check the device names very carefully when working with dd.