How can I get user input from main process when using subprocess in Python

Question

For example, program1.py call program2.py:

program1.py

subprocess.Popen("program2.py", stdin=subprocess.PIPE).communicate()

program2.py

user_input = input("Yes or No?")

But when I run program1, the program2 cannot get the user input from the main process in my case. It says "EOF when reading a line". Could you give me some advice to get user input.

Answer 1

You are not passing any data to program2.py . I assume you are using Python 3, from the use of input (instead of raw_input in Python 2). Here is how I would do it:

import subprocess
import sys

cmd = [sys.executable, 'program2.py'] 
proc = subprocess.Popen(cmd, stdin=subprocess.PIPE)
proc.communicate('Y'.encode())

Passes "Y" through to the second program. The encode() is required in Python 3, but not Python 2. This is because Python 3 strings are multi-byte, whereas the stdin stream uses single byte strings, like Python 2 strings. No changes are required at the program2.py end.