Cannot start two interactive shells using popen

Question

I have the following Python snippet, and cannot explain why it behaves the way it does.

import subprocess  
bash1 = subprocess.Popen([\"/bin/bash\",\"-l\", \"-i\         


        

Answer 1

According to the isedev hint, I opened 2 pseudoterminals. Important thing is that master process (this python script) reads and writes on the master PTY file, while child subprocess uses slave file as stdin, stdout and stderr. Bottom part of the code is just for testing how everything works.

import subprocess
import os
import pty
import select
import time

# according to> http://fleckenzwerg2000.blogspot.com/2011/10/running-and-controlling-gnu-screen-from.html
(master1, slave1) = pty.openpty()
bash1 = subprocess.Popen(["bash", "-l", "-i"], stdin=slave1, stdout=slave1, stderr=slave1)
(master2, slave2) = pty.openpty()
bash2 = subprocess.Popen(["bash", "-l", "-i"], stdin=slave2, stdout=slave2, stderr=slave2)
data = "echo 'bla'\n"

## taken from> http://stackoverflow.com/questions/14564904/how-to-send-tab-key-to-python-subprocesss-stdin
def write_all(masterPTY, data):
    """Successively write all of data into a file-descriptor."""
    while data:
        chars_written = os.write(masterPTY, data)
        data = data[chars_written:]
    return data

def read_all(masterPTY):
    r,w,x = select.select([masterPTY], [], [], 10)
    if r:
        data = os.read(masterPTY, 1024)
        return data


write_all(master1, "echo 'bla1'\n")
write_all(master2, "echo 'bla2'\n")
time.sleep(1)
print read_all(master1)
write_all(master1, "echo 'bla1'\n")
time.sleep(1)

print read_all(master2)

time.sleep(1)

os.close(master1)
os.close(slave1)
os.close(master2)
os.close(slave2)

bash1.terminate()
bash2.terminate()

print "OK"

That is it. Hope it helps someone!