urhex.py

#!/usr/bin/env python3
import fileinput
import re

def main():
    for line in fileinput.input():
        if not re.search(r'^[0-9a-fA-F]+$', line):
            continue
        print('0x', end='')
        line = line.strip().lstrip('0')
        if not line:
            print('0')
            continue
        n, m = divmod(len(line), 4)
        if m:
            print(line[:m].lower(), end='')
            if n:
                print('.', end='')
        for i in range(n):
            print(line[m + i * 4 : m + (i + 1) * 4].lower(), end='')
            if i + 1 != n:
                print('.', end='')
        print()

if __name__ == '__main__':
    main()