使用子进程和通讯在Telnet连接上执行命令

Question

This is my first query on StackExchange. Kindly excuse, if my question is already been raised and answered. If so, kindly point me to the same.

Query: I am trying to establish the telnet connection to a board and then would like run a app after that. I would like to capture both STDOUT and STDERR during whole process. Below is the snippet of my code

Code Snippet:

import subprocess
import time

#1. Establish the subprocess 
commandlist = ["telnet"] + ["10.11.12.13"]
p = subprocess.Popen(commandlist,
                     stdin = subprocess.PIPE,
                     stdout = subprocess.PIPE,
                      stderr = subprocess.PIPE)
#2. Give the login name. There is no password
p.stdin.write("root\r")
#3. Adding this for sync to avoid any overlap
time.sleep(1)
#4. Invoke the communicate to execute the application from a specied path on 10.11.12.13 system
stdout, stderr = p.communicate('sh /mnt/path/app\r')

At step (4), i tried printing the values of stdout and stderr to see whether the application 'app' has run or not. Unfortunately, it has not even executed the 'p.communicate()' line.

If any one has encountered similar problem or know the solution, kindly help me to fix the issue.

Thank you!!

Answer 1

Terminate your strings with \\n instead of \\r?

Consider using telnetlib, instead of rolling your own w/ subprocess?

And finally, if you can run an ssh server on this board, you'll be able to use paramiko and ssh channels, which will help avoid some headaches down the road.

Answer 2

You can use Pexpect Library to get your task done.

Pexpect can be used for automating interactive applications such as ssh, ftp, passwd, telnet, etc. It can be used to a automate setup scripts for duplicating software package installations on different servers.

https://pexpect.readthedocs.io/en/stable/