Pass input to commands run in terminal with python

Question

Say I have a Python 3 program like this:

print("Addition program")
num1 = int(input(">>> "))
num2 = int(input(">>> "))
print(num1 + num2)

I'm running it in the terminal and displaying the output with:

import subprocess

def run_command(command):
  p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
  return iter(p.stdout.readline, b'')

for i in run_command(["python", "file.py"]): print(i)

How can I pass inputs to the program, either in the command itself, or while its running? Thanks in advance!

Edit: I found a solution that allows me to use pipes stdin and stdout. So I can pass input with stdin.write(b'. . . .'). However, once I use this command, I have to use the .communicate() method to obtain output or else the process hangs. Right now my code is:


import subprocess
from subprocess import PIPE
import shlex

p=subprocess.Popen(["python", "file.py"], stdin=PIPE, stdout=PIPE)


one_line_output = p.stdout.readline()
print(one_line_output.decode(), end = "")

p.stdin.write(b'a line\n')

one_line_output = p.communicate()[0] # end the process
print(one_line_output.decode(), end = "")

one_line_output = p.stdout.readline()
print(one_line_output.decode(), end = "")
'''
When this line of code runs, it raises an error:
Traceback (most recent call last):
  File ". . . .", line 27, in <module>
    one_line_output = p.stdout.readline()
ValueError: readline of closed file
'''

Is there a way I can continue to pass inputs and read lines?

frab · Accepted Answer · 2021-01-18 02:28:48Z

1

Use the sys module:

import sys
print("Addition program")

num1 = sys.argv[0]
num2 = sys.argv[1]

print(num + num2)

Then you can execute the script passing the number arguments simply by:

python file.py 3 4

answered Jan 18, 2021 at 2:28

frab

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1 Comment

PythonAddict Class Over a year ago

No, I'm afraid that wont work. I dont want the input() to be removed, I'm trying to write a code editor, and I want the user to be able to either provide the inputs at the start of the program or provide inputs while the program is running

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