python - How do I get a line of the what the console returns (string) and place in a variable? -

i have code using telnet , requires login. if login incorrect, returns "incorrect login" console. want catch exception , skip doesn't stop program. tried below:

try:     session.write("username".encode('ascii') + b"\r")     session.write("password".encode('ascii') + b"\r")     ***this point console return "incorrect login"*** except sys.stdout == "incorrect login":     print(sys.stdout)     pass else:     **rest of code** 

it seems never catches output, continues on code , ends in index error (from not having data need logging in). tried searching had no luck. appreciated. i'm running python 3.3 , still learning. thanks!

edit: here telnet shows

login: badusername password: **blank b/c pw field** login incorrect  login:  

edit2: code else (edited confidentiality)

import telnetlib, time import sys, string, socket import cx_oracle  sql = "select column table"  con = cx_oracle.connect("login info blah...") cur = con.cursor() cur.execute(sql) row = cur.fetchone() rows = cur.fetchall()  def tup():     return (rows)  cur.close() con.close()  = 0  while < len(rows):        host    = tup()[i][0]     timeout = 120     print(host + ' =', end = ' ')     try:         session = telnetlib.telnet(host, 23, timeout)     except:         out = open("data.txt",'a')         out.write(host + " = failed\n")         print("failed")     else:             try:         session.write("username".encode('ascii') + b"\r")         session.write("pass".encode('ascii') + b"\r")     except sys.stdout == "incorrect login":         print(sys.stdout)         pass     else: 

take [subprocess][1] module, contains check_output method returns output of executed command string.

try this. might need change syntactical details...

prompt = '$' # or '#' or '%', shell prompt timeout = 3  try:     session.read_until(b"login:")     session.write("username".encode('ascii') + b"\r")      session.read_until(b"password:")     session.write("password".encode('ascii') + b"\r")     login_result = session.read_until(prompt, timeout) # make put whatever printed till prompt login_result. if takes more timeout seconds, can assume login failed (since prompt never came up)     ***this point console return "incorrect login"***      if(login_result[-1] != prompt):    # change -1 -2 or -3 if output trailed newline         raise exception  except exception:     print("login failure")     pass  else:     **rest of code**