Note that sprocess.stdin.write('/stop'.encode()) will not add a newline! Your subprocess is probably expecting a line of input, signified by either a newline or EOF. Closing stdin will send that EOF.

Try sending sprocess.stdin.write('/stop\n'.encode()) instead.

The equivalent command to commands.getoutput is subprocess.check_output:

from subprocess import check_output
out = check_output('tr -d "\'" < /tmp/file_1.txt > /tmp/file_2.txt', shell=True)

As far as I can understand you want pressing "c" button to kill the process that you run with subprocess. Use this recipe to detect key and write simple function to call inside a thread like this:

import subprocess
import os
import signal
import thread
from getch import _Getch

def kill(pro):
    if _Getch()() == "c":
        os.killpg(os.getpgid(pro.pid), signal.SIGTERM)

CMD="sudo apt-get update"
p = subprocess.Popen(CMD, shell=True, stdout=subprocess.PIPE)
thread.start_new_thread(kill, (p,))
while True:
    output = p.stdout.readline()
    if output:
        print output

The data may be stuck in the pipe. Add self.process.stdin.flush() after the write.

your code will send the text

import nukeprint nukequit()

with no newline, thus the python instance will not try to execute anything, everything is just sitting in a buffer waiting for a newline

From the documentation of subprocess -

Popen.communicate(input=None, timeout=None)

Interact with process: Send data to stdin. Read data from stdout and stderr, until end-of-file is reached. Wait for process to terminate. The optional input argument should be data to be sent to the child process, or None, if no data should be sent to the child. The type of input must be bytes or, if universal_newlines was True, a string.

(Emphasis mine)

You need to send in a byte-string as input to the communicate() method , Example -

from subprocess import Popen, PIPE

s = Popen("mse --cli setName.mse-set --raw",stdin=PIPE)
s.communicate(b"write_image_file(file:set.cards[1].name+'.png',set.cards[1]")

Also , you should send the command to run as a list , Example -

from subprocess import Popen, PIPE

s = Popen(['mse', '--cli', 'setName.mse-set', '--raw'],stdin=PIPE)
s.communicate(b"write_image_file(file:set.cards[1].name+'.png',set.cards[1]")

If I simulate code.exe to read the arg and then process stdin:

#!/usr/bin/env bash
echo "arg: $1"
echo "stdin:"
while read LINE
do
  echo "$LINE"
done < /dev/stdin

and slightly update your code:

import os
from subprocess import Popen, PIPE

cwd = os.getcwd()
exe = os.path.join(cwd, 'foo.sh')
p = Popen([exe, '25'], stdin=PIPE, stdout=PIPE, stderr=PIPE)
out, err = p.communicate(input='aaa\nbbb\n')
for line in out.split('\n'):
    print(line)

Then the spawned process outputs:

arg: 25
stdin:
aaa
bbb

If input is changed without a \n though:

out, err = p.communicate(input='aaa')

Then it doesn't appear:

arg: 25
stdin:

Process finished with exit code 0

So you might want to look closely at the protocol between both ends of the pipe. For example this might be enough:

input='ping 8.8.8.8\n'

Hope that helps.