AttributeError: 'NoneType' object has no attribute 'exec_command', when converting code lines into a function, in python

Question

This question is related to this one: How to use sockets to send user and password to a devboard using ssh

How can I put CODE A into a function? Explain me what am I doing wrong.

CODE A

import paramiko
import os

#Server's data
IP = '172.16.2.82'
PORT = 22
USER = 'mendel'
PASSWORD = 'mendel'


ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(hostname = IP, port=PORT, username = USER, password = PASSWORD)

stdin, stdout, stderr = ssh.exec_command('cd coral/tflite/python/examples/classification/Auto_benchmark\n python3 auto_benchmark.py')
output = stdout.readlines()
type(output)
print('\n'.join(output))
ssh.close()

This is my attempt:

def initialize_ssh():
    n = 0
    while n <= 10:
        try:
            ssh = paramiko.SSHClient()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(hostname = IP, port=PORT, username = USER, password = PASSWORD)
            return
        except paramiko.AuthenticationException:
            print("Authentication failed, please verify your credentials: %s")
        except paramiko.SSHException as sshException:
            print("Unable to establish SSH connection: %s" % sshException)
            n += 1
            continue
    raise Exception


def main():
    ssh = initialize_ssh()
    stdin, stdout, stderr = ssh.exec_command('cd coral/tflite/python/examples/classification/Auto_benchmark\n python3 auto_benchmark.py')
    output = stdout.readlines()
    type(output)
    print('\n'.join(output))
    ssh.close()


if __name__ == '__main__':
    main()

EDIT AFTER SUGGESTIONS FROM COMMENTS

def main():
    ssh = initialize_ssh()
    stdin, stdout, stderr = ssh.exec_command('ls')
    output = stdout.readlines()
    type(output)
    print('\n'.join(output))
    ssh.close()
    return ssh    <------------------- HERE IS THE CHANGE

You do `ssh = initialize_ssh()` but you don't return `ssh` from the function. — Matthias, Jun 17 '20 at 19:34
I still get the same error: ```AttributeError: 'NoneType' object has no attribute 'exec_command'``` — Aizzaac, Jun 17 '20 at 19:37
No, @Matthias meant return ssh from initialise_ssh(). You only have a bare return after ssh.connect(...) — quamrana, Jun 17 '20 at 19:43

score 1 · Accepted Answer · answered Jun 17 '20 at 19:47

Your first change should be to return ssh:

def initialize_ssh():
    n = 0
    while n <= 10:
        try:
            ssh = paramiko.SSHClient()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(hostname = IP, port=PORT, username = USER, password = PASSWORD)
            return ssh # the return is here
        except paramiko.AuthenticationException:
            print("Authentication failed, please verify your credentials: %s")
        except paramiko.SSHException as sshException:
            print("Unable to establish SSH connection: %s" % sshException)
            n += 1
            continue
    raise Exception

AttributeError: 'NoneType' object has no attribute 'exec_command', when converting code lines into a function, in python

1 Answers1