Subprocess command prompt (Windows)

[arnaur]

Hello,
I'm making a little program that runs a cmd command on Windows. That command needs a password and a verification of the password from the user to be typed it in the terminal. What I want to do is to send the password myself from the program to the terminal. The program looks something like this:

from subprocess import *
p = Popen("Command that does something and asks  for a password", stdin=PIPE, stdout=PIPE, shell=True)

I have tried different solutions but none of them have worked. I've tried this:

p.communicate(b"secret password\n") #I have tried with and without the \n

And also this:

p.stdin.write("secret password")

I don't get any error message, but the terminal still asks me for password.