ustealth in python to hide FAT32 partitions from Wii U

ustealth-hide.sh

#!/bin/bash

if [ $# -eq 0 ]
then
    echo "Missing argument: device"
    exit 1
fi

printf '\xAB' | dd of=$1 bs=1 seek=511 count=1 conv=notrunc

partprobe $1

exit 0

ustealth-show.sh

#!/bin/bash

if [ $# -eq 0 ]
then
    echo "Missing argument: device"
    exit 1
fi

printf '\xAA' | dd of=$1 bs=1 seek=511 count=1 conv=notrunc

partprobe $1

exit 0

ustealth.py

#!/bin/env python3

import sys
import subprocess


helpstr = """
ustealth.py: hides or shows partitions from Wii U.
Usage:
\t./ustealth.py hide <block device>
\t./ustealth.py show <block device>

Examples:
\tsudo ./ustealth.py hide /dev/sdc
\tsudo ./ustealth.py show /dev/sdc
"""

byte_offset = 511
hidden_byte = b'\xAB'
visible_byte = b'\xAA'


def change_byte(device, offset, oldbyte, newbyte):
    with open(device, mode='r+b', buffering=0) as dev:
        dev.seek(offset)
        data = dev.read(1)
        if data == oldbyte:
            dev.seek(offset)
            dev.write(newbyte)
        else:
            sys.exit("Error: expected {}, found {}.".format(oldbyte, data))

    print("Trying to re-read partition table.")
    cmds = [
        ['blockdev', '-v', '--rereadpt', device],
        ['partprobe', '-s', device],
        ['partx', '-vu', device],
        ['hdparm', '-z', device]
    ]
    for cmd in cmds:
        try:
            result = subprocess.run(cmd,
                stdout=subprocess.PIPE,
                stderr=subprocess.STDOUT,
                universal_newlines=True)
            if result.returncode == 0:
                print("Executed:\n\t{}".format(" ".join(cmd)))
                print(result.stdout)
                break
        except:
            pass


if len(sys.argv) != 3:
    print(helpstr)
    sys.exit("Error: wrong number of arguments.")

action = sys.argv[1]
device = sys.argv[2]

if action == "show":
    print("Action: show partitions.")
    change_byte(device, byte_offset, hidden_byte, visible_byte)
elif action == "hide":
    print("Action: hide partitions.")
    change_byte(device, byte_offset, visible_byte, hidden_byte)        
else:
    print(helpstr)
    sys.exit("Error: invalid action: {}.".format(action))