Command-line tool to unmount and create iso image of a disk, under OSX

iso

#!/bin/sh
# Create disk images
#
# Put this in ~/bin/iso and add ~/bin/ to your $PATH, then run `iso`.

set -e

if [ "$1" ] && [ "$2" ]; then
  diskutil unmountDisk "$1"
  echo "Creating image at $2. Press ctrl-t to see progress."
  dd "if=/dev/$1" "of=$2"
else
  echo 'Usage: iso DISK_NAME ISO_PATH'
  echo 'Example: iso disk3 ~/cd.iso'
  echo
  echo 'To find the disk name, use the `drutil status` command:'
  echo
  drutil status
fi