How to create idempotent values in bash

idempotent.sh

#!/bin/bash

# Generate Pod CIDR based on 10.240.0.0/14 address space
#   generate a md5 from hostname to get a generated but idempotent hex value.
idempotent_hex=$(hostname | md5sum | cut -c 1-4)

#   turn this hex value into an integer "16# means base 16"
idempotent_int=$((16#$idempotent_hex))

#   second octet - limit to 0-4 and add 240
b=$(( idempotent_int % 4 + 240 ))

#   third octet - limit to 0-255
c=$(( idempotent_int % 255 ))

#   fourth octet - limit 0 or 1 (1 being 128)
d=$(( idempotent_int % 1 ))

if [[ $d -eq 1 ]]
then
    d=128
fi

echo "Generated Pod CIDR 10.$b.$c.$d/25"

Based off of https://stackoverflow.com/a/33379756/7554392