Convert MBR (or any 512-byte binary input) into a script that outputs the data but with editable partition fields

mbr2script.sh

#!/bin/bash
# wget https://gist.githubusercontent.com/countingpine/78d198b2f3d7271427d3fa49c787b135/raw/mbr2script.sh
set -e
set -u

echo '#!/bin/bash'
echo 'set -e'
echo 'set -u'

# Hexdump 512 bytes from stdin
a=( $(xxd -c1 -l 512 "${1--}" | awk '{print "0x" $2}') )

# Raw dump first 446 bytes
data="'"
for i in {0..445}; do
  data+=$(printf '\\x%x' "${a[$i]}")
done
data+="'"
echo "printf '%b' $data"

# Function to construct partitions in hexdump
function part() {
  set -u
  local status=$(($1))
  local chs1=$(($2))
  local type=$(($3))
  local chs2=$(($4))
  local lba1=$(($5))
  local lba2=$(($6))
  printf '%b' $(
    printf '\\x%x' \
      $status \
      $(($chs1 & 255)) $(($chs1 >> 8 & 255)) $(($chs1 >> 16 & 255)) \
      $type   \
      $(($chs2 & 255)) $(($chs2 >> 8 & 255)) $(($chs2 >> 16 & 255)) \
      $(($lba1 & 255)) $(($lba1 >> 8 & 255)) $(($lba1 >> 16 & 255)) $(($lba1 >> 24 & 255)) \
      $(($lba2 & 255)) $(($lba2 >> 8 & 255)) $(($lba2 >> 16 & 255)) $(($lba2 >> 24 & 255))
  );
}

# Copy above function into script
awk '/^function part/ {fn=1};  fn;  /^[}]$/ {fn=0}' "$0"


# Dump partition fields
echo "#  status chs1     type chs2     start  length"
for i in {0..3}; do
  for j in {0..15}; do
    off=$((446+$i*16+$j))
    b[$j]=${a[$off]}
  done
  status=${b[0]}
  chs1=$((${b[1]} | ${b[2]} << 8 | ${b[3]} << 16))
  type=${b[4]}
  chs2=$((${b[5]} | ${b[6]} << 8 | ${b[7]} << 16))
  lba1=$((${b[ 8]} | ${b[ 9]} << 8 | ${b[10]} << 16 | ${b[11]} << 24))
  lba2=$((${b[12]} | ${b[13]} << 8 | ${b[14]} << 16 | ${b[15]} << 24))
  printf "part 0x%02x 0x%06x 0x%02x 0x%06x %d %d\n" $status $chs1 $type $chs2 $lba1 $lba2
done

# Dump last two bytes (should be 55 AA)
data='$'"'"
for i in {510..511}; do
  data+=$(printf '\\x%x' "${a[$i]}")
done
data+="'"
echo "echo -n $data"