Partition extraction from image files

extractpartition.sh

#!/bin/bash
# Extracts a partition from a full disk image containing a partition table

# Colors
red='\033[0;31m'
green='\033[0;32m'
yellow='\033[0;33m'
cyan='\033[0;36m'
nc='\033[0m' # no color

# Text
ok="[ ${green}OK${nc} ]"
noy="[ ${yellow}NO${nc} ]"
err="[ ${red}ERROR${nc} ]"
info="[ ${cyan}INFO${nc} ]"

usage() {
    echo "Usage:" 1>&2
    echo "$(basename $0) IMAGEFILE" 1>&2
}

# Make sure script is run with one param
if [[ $# -ne 1 ]]; then
    usage
    exit 1
fi

img="$1"

# Lines containing header informartion in fdisk
skip=9

# Sector/Block size
bs=512

pcount=$(fdisk "$img" -l | tail -n+$skip | wc -l)
psize=( $(fdisk "$img" -l -o Size | tail -n+$skip | sed 's/ /\n/g') )
pstart=( $(fdisk "$img" -l -o Start | tail -n+$skip | sed 's/ /\n/g') )
psectors=( $(fdisk "$img" -l -o Sectors | tail -n+$skip | sed 's/ /\n/g') )

echo "Your file has $pcount partitions with the following sizes:"

for p in $(seq 0 $((pcount-1))); do
    echo -e "    ${cyan}#$p${nc}: ${psize[$p]}"
done

echo
echo -ne "Which one do you want to extract? ${cyan}"

read partition
echo -ne "${nc}"

if [[ $partition =~ ^-?[0-9]+$ && $partition -lt $pcount && $partition -ge 0 ]]; then
    echo -e "You chose ${cyan}#$partition${nc} (${psize[$partition]})\n"
else
    echo -e "Your input was not valid, aborting..."
    exit 1
fi

tgt="$img.p$partition"

echo -e "Extracting to $tgt..."
skip=${pstart[$partition]}
count=${psectors[$partition]}
size=$(($count*$bs))
dd if="$img" bs="$bs" skip="$skip" count="$count" | pv -tpreb -s "$size" | dd of="$tgt" &> /dev/null