A script to convert an .iso file to a format suitable for creating a bootable USB (Mac OS X-specific)

iso-to-usb.sh

#!/bin/sh

set -e

if [ "$1" = "" -o "$2" = "" ]; then
	echo "Usage: $0 /path/to/source.iso /dev/usb_disk_device" >&2
	exit 1
fi

iso_source="$1"
usb_disk="$2"

if [ ! -f "$iso_source" ]; then
	echo "Source does not exist: $iso_source" >&2
	exit 2
fi

if [ ! -b "$usb_disk" -a ! -c "$usb_disk" ]; then
	echo "The selected USB disk device does not exist: $usb_disk (or is neither a block-special device, nor a character-special one)" >&2
	exit 3
fi

echo "Converting $iso_source to .img..."
hdiutil convert -format UDRW -verbose -o "$iso_source.img" "$iso_source"

if [ -f "$iso_source.img.dmg" ]; then
	mv -v "$iso_source.img.dmg" "$iso_source.img"
fi

echo "Unmounting the USB drive $usb_disk..."
diskutil unmountDisk "$usb_disk"

if [ -b "$usb_disk" ]; then
	fast_usb_disk="/dev/r`basename $usb_disk`"
	if [ -c "$fast_usb_disk" ]; then
		echo "Using $fast_usb_disk as it should be faster than $usb_disk"
	else
		fast_usb_disk="$usb_disk"
	fi
else
	fast_usb_disk="$usb_disk"
fi

echo "Copying the image file to $fast_usb_disk..."
sudo dd if="$iso_source.img" of="$fast_usb_disk" bs=1m

echo "Copying done, ejecting $usb_disk..."
diskutil eject "$usb_disk"

echo "Done."