Replace a marked block part of a file, with the contents of another file. Ex.: replace.py file.html data.txt //begin //end

replace.py

import sys

orig = sys.argv[1] if len(sys.argv) > 1 else 'kocka.html'
data = sys.argv[2] if len(sys.argv) > 2 else 'L5_A-17_365000napig_bennmarado_3650napig.txt'
start = sys.argv[3] if len(sys.argv) > 3 else '// begin_data'
end = sys.argv[4] if len(sys.argv) > 4 else '// end_data'
no_backup = True if len(sys.argv) > 5 and sys.argv[5] == 'no_backup' else False
clean = True if data == 'clean' else False

with open(orig, 'r+', encoding='utf-8') as f:
  content = f.read()

  s = content.find(start)
  e = content.rfind(end)
  if s != content.rfind(start) or e != content.find(end):
    print("More than one match for replacement block! Exiting.")
    exit()
  if s == content.find(start + '\n'):
    start += '\n'
  if e - len('\n') == content.rfind('\n' + end):
    end = '\n' + end
    e -= len('\n')
  #to_replace = content[s + len(start):e]

  if not no_backup:
    with open(orig + '.bak', 'w', encoding='utf-8') as f2:
      f2.write(content)

  f.seek(0)
  f.write(content[0:s + len(start)])
  if not clean:
    with open(data, 'r', encoding='utf-8') as f2:
      for l in f2:
        f.write(l)
      #f.write(content.replace(to_replace, f2.read())) # MemoryError if data file too large
  f.write(content[e:])
  f.truncate()