a terrible idea

#!/bin/bash
echo
echo "Disk clone wizard, part one"
echo "2014-01-30, version 1.0"
echo "by 'ed' on rizon irc"
echo
echo "About to create a full backup image of your hard disk."
echo "Make sure that no external storage is connected:"
echo "-- Remove all USB hard drives"
echo "-- Remove all USB memory sticks"
echo
read -n 1 -r -p "Press a key to continue."
echo
while [ true ]
do
    # df -h > df_one
    export drive=$( #)
        cat df_one |
        grep -E   '^/dev/sd' |
        sed -E 's/^(........).*/\1/' |
        uniq
    )
    if [ $(echo "$drive" | grep dev | wc -l) -ne 1 ]
    then
        echo "You have external media connected."
        echo "Please disconnect all USB hard disks and memory sticks."
        read -n 1 -r -p "Press a key to try again."
        echo
    else
        echo
        echo "Found primary hard disk: $drive"
        break
    fi
done
echo
echo "Please connect your external hard disk."
echo "Wait until a file explorer appears."
echo "Close the file explorer."
echo
read -n 1 -r -p "Press a key to continue."
echo
while [ true ]
do
    # df -h > df_two
    export shuttle=$( #)
        cat df_two |
        grep -v "$drive"
        grep -E   '^/dev/sd' |
        sed -E 's/^(........).*/\1/' |
        uniq
    )
    num=$(echo "$shuttle" | grep dev | wc -l);
    if [ $num -gt 1 ]
    then
        echo "Found multiple external media."
        echo "Something is wrong."
        echo "Aborting."
        echo
        exit
    fi
    if [ $num -ne 1 ]
    then
        echo "Could not find the external media."
        read -n 1 -r -p "Press a key to try again."
        echo
    else
        echo
        echo "Found external hard disk: $shuttle"
        break
    fi
done