Copy text file by using buffer

buffer_size = 100000

# input = open('sowpods.txt')  # CRLF issue - extra bytes
input = open('sowpods.bak')
output = open('sowpods.tmp', 'w')

buffer = input.read(buffer_size)
while len(buffer) > 0:
    output.write(buffer)
    print('.', end='')
   buffer = input.read(buffer_size)

input.close()
output.close()