Text11. Дан текстовый файл. Продублировать в нем все пустые строки.

Решение на Python 3:

import random
import string
import os
import sys

#file for reading and adding empty row
file1 = "text11.txt"

#file for temporary data
N = random.randrange(5,8)
S = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N))
temp_file = "temp_" + S + ".txt"
print("Temp file:",temp_file)
print("Write to:",temp_file)
try:
    f_temp = open(temp_file, "w")
    try:
        try:
            with open(file1,'r') as f_open:
                for line in f_open:
                    f_temp.write(line)
                    if line.strip("\n") == "":
                        f_temp.write(line)
        except IOError:
            print("Read error:",file1)
    finally:
        f_temp.close()
except IOError:
    print('Write error: ',file1)

print("Rename {0} to {1}".format(temp_file,file1))
try:
    os.rename(temp_file, file1)
except WindowsError:
    os.remove(file1)
    os.rename(temp_file, file1)
except OSError as e:
    print("Error:", e)