shrink.sh

#!/bin/bash

DEVICE=/dev/$1 #/dev/sdc
OUTPUT=$2 #./V0.2.img

PART=$(fdisk $DEVICE -l | tail -1 | awk '{print $1}'  | sed 's/[^0-9]*//g' )

echo $DEVICE
echo $OUTPUT
echo $PART

if [ $PART > 4 ]; then
    TYPE="l"
    echo "LOGICAL (EXTENDED)"
else
    TYPE="p"
    echo "PRIMARY"
fi

echo $TYPE

sleep 2

fsck.vfat -y ${DEVICE}1
e2fsck -y -f ${DEVICE}$PART

for pass in {1..10}
do

result=$(resize2fs -M ${DEVICE}$PART)
if [ -z "$result" ]; then
    break
fi

blocks=$(echo "$result" | grep "Resizing" | awk '{print $7}')
block_size=$(echo "$result" | grep "Resizing" | awk '{print $8}' | cut -d "(" -f2 | cut -d "k" -f1)
new_size=$(($blocks * $block_size))
PART_START=$(fdisk $DEVICE -l | grep ${DEVICE}$PART | awk '{print $2}')
PART_END=+${new_size}K

fdisk $DEVICE <<EOF
d
$PART
n
$TYPE
$PART
$PART_START
$PART_END
w
EOF

echo "Size after Pass #${pass}: $(($new_size/1024))MB"

done

block_size=$(fdisk $DEVICE -l | grep "Sector size" | awk '{print $4}')
end_sector=$(fdisk $DEVICE -l | tail -1 | awk '{print $3}')

mb_size=$(((($end_sector * $block_size)/1048576)+1))

echo "Block Size: $block_size"
echo "Total Sectors: $end_sector"
echo ""
echo "** IMAGE SIZE: $mb_size MB **"
echo ""

echo "STARTING DD"
echo "$DEVICE > $OUTPUT"
dd bs=1M count=$mb_size if=$DEVICE of=$OUTPUT
echo "DONE"