One Python script giving "user input" to another python script

Question

this is my first question, I hope I'm doing this right. let's say I have these this file:

"simple.py":

a=raw_input("your name?")
print "Hello",a

but with a different script, I want to execute "simple.py" many time and giving the input automatically, that would work like:

"everyone.py"

run simple.py input=Alice
run simple.py input=Bob
...

to get "Hello Alice" "Hello Bob" ...

I know it's possible to make "everyone.py" run "simple.py" by using os.system, but is there any practical way to do something like this? And what if the first script asks for input several times?

It's important that I CANNOT EDIT SIMPLE.PY, only the other file

Thanks in advance :)

Answer 1

import sys
print "Hello",sys.argv[1]

running C:\Python26\python.exe simple.py Alice would produce

Hello Alice

There's a good example on how to get input from the system into a python application here:

• http://www.tutorialspoint.com/python/python_command_line_arguments.htm

Since you didn't mention that you can not modify simple.py then you would need to automaticly input things into the raw_input() and the fastest way to do this is simply to pipe in data into the script as "input":

C:> echo "Alice" | run simple.py

Answer 2

For a case as simple as simple.py, you should be able to use subprocess.Popen:

import subprocess

child = subprocess.Popen(['python', 'simple.py'], stdin=subprocess.PIPE)
child.communicate('Alice')

For more complex cases, the Pexpect module may be useful. It helps automate interaction with normally-interactive programs by providing more convenient, robust interfaces to send input, wait for prompts, and read output. It should work in cases where Popen doesn't work or is more annoying.

import pexpect

child = pexpect.spawn('python simple.py')
child.expect("your name?")
child.sendline('Alice')

Answer 3

Unfortunately neither of the answers above worked for me so I came up with a third solution for others to try.

To send inputs from one python file to another (python version 3.7), I used three files.

1. File for running the subprocess
2. File for outputs (very simple)
3. File that needs the inputs

Here are the three files in the same order as above.

You don't need to print out the output, but I'll include the terminal output below the file examples. The subprocess file:

from subprocess import Popen,PIPE

p1 = Popen(["python","output_file.py"], stdout=PIPE)
p2 = Popen(["python", "input_file.py"], stdin=p1.stdout, stdout=PIPE)
p1.stdout.close()

output = p2.communicate()[0]

print(output)

The output file is very simple and there may be a way to work around it. Nevertheless, here is my version:

print(1)
print(2)
print('My String')

The input file requires type casting for numbers.

i = input('Enter a number: ')
j = input('Enter another: ')
k = int(i) + int(j)
print(k)
l = input('Tell me something. ')
print(l)

Here is the terminal output:

b'Enter a number: Enter another: 3\r\nTell me something. My String!\r\n'