To create a Windows 7 installer USB mass storage in Debian GNU/Linux, these tools are needed:

Steps for creating the installer:

  1. Run fdisk on the device.
    fdisk /dev/sdb
  2. Create a new empty DOS partition table.
    Command (m for help): o
    Building a new DOS disklabel with disk identifier 0x7ebabd73.
  3. Create a single primary partition.
    Command (m for help): n
    Command action
    e   extended
    p   primary partition (1-4)
    Partition number (1-4, default 1): 1
    First sector (2048-32767, default 2048):
    Using default value 2048
    Last sector, +sectors or +size{K,M,G} (2048-32767, default 32767):
    Using default value 32767
  4. Set the partition bootable flag to active.
    Command (m for help): a
    Partition number (1-4): 1
  5. Write the change to the storage device.
    Command (m for help): w
    The partition table has been altered!
    Syncing disks.
  6. Create a new NTFS volume in the new partition.
    mkfs.ntfs -f /dev/sdb1
  7. Mount the filesystem.
    mount /dev/sdb1 /mnt/win7
  8. Copy the content of Windows 7 installer.
    rsync --progress --stats -rv /mnt/win7dvd/* /mnt/win7/
  9. Unmount the filesystem.
    umount /mnt/win7
  10. Run ms-sys
    ms-sys -7 /dev/sdb