import os

os.system("del an_important_file.txt")

os.system("dir")

os.system("notepad an_important_file.txt")
print("finished")

import subprocess

p = subprocess.Popen("notepad an_important_file.txt")
print("subprocess opened", p.pid)
print(p.wait())

p = subprocess.Popen("git add", stdout=subprocess.PIPE, stderr=subprocess.PIPE)
print("subprocess opened", p.pid)
print(p.wait())

p.stderr.readlines()

for line in p.stderr:
    print(line)