gistfile1.txt

import os
import subprocess
import select

process = subprocess.Popen("/bin/bash", shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE);

process.stdin.write("export MyVar=\"Test\"\n")
process.stdin.write("echo ${MyVar}\n")
process.stdin.write("echo ${MyVar}\n")

try:
    i,o,e = select.select([process.stdout], [], [], 5) # 5 second timeout
    stdout = os.read(i[0].fileno(), 1024)
except IndexError:
    # nothing was written to the pipe in 5 seconds
    stdout = ""
print "stdout: " + stdout 

process.stdin.write("echo $MyVar\n")

try:
    i,o,e = select.select([process.stdout], [], [], 5) # 5 second timeout
    stdout = os.read(i[0].fileno(), 1024)
except IndexError:
    # nothing was written to the pipe in 5 seconds
    stdout = ""
print "stdout: " + stdout 

########
Output:

stdout: Test

stdout: Test