Find Unique Characters in a File

Question

I have a file with 450,000+ rows of entries. Each entry is about 7 characters in length. What I want to know is the unique characters of this file.

For instance, if my f

Answer 1

A very fast solution would be to make a small C program that reads its standard input, does the aggregation and spits out the result.

Why the arbitrary limitation that you need a "script" that does it?

What exactly is a script anyway?

Would Python do?

If so, then this is one solution:

import sys;

s = set([]);
while True:
    line = sys.stdin.readline();
    if not line:
        break;
    line = line.rstrip();
    for c in line.lower():
        s.add(c);

print("".join(sorted(s)));