Serial from environment

#!/bin/bash

# Docker environment variabeles

: ${HOST_SERIAL:=''}

: ${GUEST_SERIAL:=''}

permanent="DSM"

serialstart="2000"

IMG="/storage"

[ ! -d "$IMG" ] && echo "Storage folder (${IMG}) not found!" && exit 69

#If environment variabele not set fall back to file

if [ -z "$HOST_SERIAL" ]; then

  FILE="${IMG}/host.serial"

  if [ ! -f "$FILE" ]; then

    SERIAL="$(echo "$serialstart" | tr ' ' '\n' | sort -R | tail -1)$permanent"$(printf "%06d" $((RANDOM % 30000 + 1)))

    echo $SERIAL > "$FILE"

  fi

  HOST_SERIAL=$(cat "${FILE}")

fi

#If environment variabele not set fall back to file

if [ -z "$GUEST_SERIAL" ]; then

  FILE="${IMG}/guest.serial"

  if [ ! -f "$FILE" ]; then

    SERIAL="$(echo "$serialstart" | tr ' ' '\n' | sort -R | tail -1)$permanent"$(printf "%06d" $((RANDOM % 30000 + 1)))

    echo $SERIAL > "$FILE"

  fi

  GUEST_SERIAL=$(cat "${FILE}")

fi

./run/serial.bin -cpu=$CPU_CORES \

                -buildnumber=42962 \