Python script that allows me to use a custom org2md post-processor after pandoc's conversion

fixmd.py

import sys
import re

lines = []

def fix_first_line(line):
    is_jekyll_regex = re.compile("^---", re.IGNORECASE)
    is_jekyll = re.search(is_jekyll_regex, line)

    if is_jekyll:
        lines.append('---\n')
        lines.append('layout: post\n')
        regex = re.compile("title: \"(.*)\"", re.IGNORECASE)
        result = re.search(regex, line)
        if result:
            title = result.group(1)
            lines.append('title: "' + title + '"\n')
            regex_date = re.compile("date: ((\d+\-){2}\d+ (\d+:){2}\d+)", re.IGNORECASE)
            date_result = re.search(regex_date, line)
            if date_result:
                date = date_result.group(1)
                lines.append('date: ' + date + '\n')
                regex_category = re.compile('category: (.*) ---', re.IGNORECASE)
                category_result = re.search(regex_category, line)
                if category_result:
                    category = category_result.group(1)
                    lines.append('category: ' + category + '\n---\n')
    else:
        lines.append(line)

with open(sys.argv[1]) as f:
    content = f.readlines()
    regex = re.compile("^``` ([\w].*)", re.IGNORECASE)

    i = 0
    for line in content:
        if i > 0:
            result = re.search(regex, line)
            if result:
                language = result.group(1)
                starting = "```" + language + '\n'
                lines.append(starting)
            else:
                replaced = re.sub(r"\\`(\w)", r'`\1', line)
                replaced = re.sub(r"\\` ", r'`   ', replaced)
                lines.append(replaced)
        else:
            fix_first_line(line)
            i += 1

f = open(sys.argv[1], 'w')
for line in lines:
  f.write("%s" % line)