Quick Python Diff

If you need a quick, cross-platform diff between files that makes a nice HTML document for your perusal, Python has your back:

import difflib

first_name = 'firstname.txt'
second_name = 'secondname.txt'
diff_name = 'diff.html'

with open(first_name, 'r', encoding='utf_8') as first:
    fromlines = first.readlines()

with open(second_name, 'r', encoding='utf_8') as second:
    tolines = second.readlines()

with open(diff_name, 'w', encoding='utf_8') as output:
    output.write(difflib.HtmlDiff().make_file(fromlines, tolines,
                                              first_name, second_name))

If you need more functionality, check out vimdiff, a more featureful version of this script at the python docs, and the linux tools diff and sdiff.