Print SSH output from Cisco Router to a text file

Question

I am a newbie to Python as well as the programming world. After a bit of research for the past 2 days am now able to successfully SSH into the Cisco router and execute set of commands. However my original goal is to print the resultant output to a text file. Checked lots of posts by forum members which helped me in constructing the code, but I couldn't get the result printed on the text file. Please help.

Here is my code:

import paramiko
import sys
import os

dssh = paramiko.SSHClient()
dssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
dssh.connect('10.0.0.1', username='cisco', password='cisco')  
stdin, stdout, stderr = dssh.exec_command('sh ip ssh')
print stdout.read()
f = open('output.txt', 'a')
f.write(stdout.read())
f.close()
dssh.close()

Answer 1

stdout.read() will read the content and move the file pointer forward. As such, subsequent calls will not be able to read the content again. So if you want to print the content and write it to a file, you should store it in a variable first and then print and write that.

---

Instead of mentioning the IP address directly on the code, is it possible for me to fetch it from list of IP addresses (mentioned line by line) in a text file?

You can read lines from a file like this:

with open('filename') as f:
    for line in f:
        # Each line will be iterated; so you could call a function here
        # that does the connection via SSH
        print(line)