Text7. Дана строка S и текстовый файл. Добавить строку S в начало файла.

Решение на Python 3:

import random
import string

file1 = "text07.txt"

N = random.randrange(1,20)
S = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N))
print("String:",S)

content = ""
try:
    with open(file1,'r') as f:
        content = f.read()
except IOError:
    print('Open error: ',file1)

print("Write string to ",file1)
try:
    f = open(file1, "w")
    try:
        f.write(S+"\n")
    finally:
        f.close()
except IOError:
    print('Write error: ',file1)

print("Append content to ",file1)
try:
    f = open(file1, "a")
    try:
        f.write(content)
    finally:
        f.close()
except IOError:
    print('Append error: ',file1)