Tip: Convert a Windows DVD ISO to a bootable USB key using guestfish

Situation: You have a Windows DVD (or ISO), but like any sane person in 2013 you don’t have a DVD drive on the computer. You want to convert the Windows DVD into a bootable USB key. There are many recipes for this online, but they all require another Windows machine and of course cannot be automated.

However with guestfish (and the always brilliant SYSLINUX doing most of the heavy lifting), this script will unpack the ISO and turn it into a bootable USB key.

Notes:

1. I am not going to support this script. You will need to read the script, look up the commands in the guestfish man page, and understand what it does. Any requests for help will be deleted unread.
2. You need to edit the USB key device before using the script.
3. You need libguestfs ≥ 1.21 with SYSLINUX support compiled in.

#!/bin/bash -

guestfish <<'EOF'
trace on

add-ro en_microsoft_hyper-v_server_2012_x64_dvd_915600.iso

# NB: The next line MUST be changed to your USB drive.
# ANYTHING ON THIS DRIVE WILL BE OVERWRITTEN WITHOUT WARNING.
add /dev/sdX

run

# Inside the appliance, /dev/sda = DVD, /dev/sdb = USB.
# THESE ARE NOT RELATED TO HOST DISK NAMES.

echo "Partitioning the USB disk ..."
part-init /dev/sdb mbr
part-add /dev/sdb p 63 -1
part-set-mbr-id /dev/sdb 1 0xb
part-set-bootable /dev/sdb 1 true
mkfs vfat /dev/sdb1

echo "Copying the contents of the DVD to the USB key ..."
mkmountpoint /cd
mkmountpoint /usb
mount /dev/sda /cd
mount /dev/sdb1 /usb
# XXX We should add cp-r command XXX
debug sh "cp -rP /sysroot/cd/* /sysroot/usb"
#glob cp-a /cd/* /usb
umount /cd
umount /usb
rmmountpoint /cd
rmmountpoint /usb

echo "Making the USB key bootable using SYSLINUX ..."
syslinux /dev/sdb1
mount /dev/sdb1 /
upload /usr/share/syslinux/chain.c32 /chain.c32
write /syslinux.cfg "DEFAULT windows\n\nLABEL windows\nCOM32 chain.c32\nAPPEND fs ntldr=/bootmgr\n"
umount /dev/sdb1
upload /usr/share/syslinux/mbr.bin /dev/sdb

echo "Finished."

EOF