chars_in_file.py takes a list of filepaths (to files encoded using utf-8). prints a list of the characters encountered.

chars_in_file.py

#!/usr/bin/env python
import codecs
import sys
chars = set()
for filepath in sys.argv[1:]:
    with codecs.open(filepath, 'r', encoding='utf-8') as fo:
        for line in fo:
            chars.update(iter(line))
c = list(chars)
c.sort()
for i in c:
    sys.stdout.write(u'{}\t {}\n'.format(i, repr(i)).encode('utf-8'))
sys.stderr.write('{} different characters found\n'.format(len(c)))