List all words that can be formed by capitalising letters in a given word.

kolcaps.py

#!/usr/bin/python3

import sys

DICT = '/usr/share/dict/words'

def subs(s):
    for i in range(len(s)):
        for s2 in subs(s[i + 1:]):
            yield s[i] + s2
    yield ''

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print('Usage: {} NAME [ <DICT ]'.format(sys.argv[0]))
        sys.exit(1)

    name = ''.join(c for c in sys.argv[1].lower() if c.isalpha())

    dic = sys.stdin if not sys.stdin.isatty() else open(DICT)
    wordpool = set(l.strip().lower() for l in dic)
    dic.close()

    for s in sorted([s for s in subs(name) if s in wordpool],
                    key=len, reverse=True):
        print(s)

usage

$ ./kolcaps.py Cairnarvon | head
cairn
cairo
cairn
cairo
cairn
canon
arron
aaron
cain
cain
$ ./kolcaps.py Cairnarvon </usr/share/dict/french | head
canon
cira
cran
car
car
car
con
air
air
ira