How do you execute multiple commands in a single session in Paramiko? (Python)

def exec_command(self, command, bufsize=-1):
    #print "Executing Command: "+command
    chan = self._transport.open_session()
    chan.exec_command(command)
    stdin = chan.makefile('wb', bufsize)
    stdout = chan.makefile('rb', bufsize)
    stderr = chan.makefile_stderr('rb', bufsize)
    return stdin, stdout, stderr

When executing a command in paramiko, it always resets the session when you run exec_command.
I want to able to execute sudo or su and still have those privileges when I run another exec_command.
Another example would be trying to exec_command(“cd /”) and then run exec_command again and have it be in the root directory. I know you can do something like exec_command(“cd /; ls -l”), but I need to do it in separate function calls.

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Non-Interactive use cases

This is a non-interactive example… it sends cd tmp, ls and then exit.

import sys
sys.stderr = open('/dev/null')       # Silence silly warnings from paramiko
import paramiko as pm
sys.stderr = sys.__stderr__
import os

class AllowAllKeys(pm.MissingHostKeyPolicy):
    def missing_host_key(self, client, hostname, key):
        return

HOST = '127.0.0.1'
USER = ''
PASSWORD = ''

client = pm.SSHClient()
client.load_system_host_keys()
client.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))
client.set_missing_host_key_policy(AllowAllKeys())
client.connect(HOST, username=USER, password=PASSWORD)

channel = client.invoke_shell()
stdin = channel.makefile('wb')
stdout = channel.makefile('rb')

stdin.write('''
cd tmp
ls
exit
''')
print stdout.read()

stdout.close()
stdin.close()
client.close()

Interactive use cases

If you have an interactive ssh use case, paramiko can handle it but this answer won’t help… I personally would use something based on exscript (which uses paramiko) or pexpect for interactive ssh sessions.

Method 2

Try creating a command string separated by n character. It worked for me.
For. e.g. ssh.exec_command("command_1 n command_2 n command_3")

Method 3

Strictly speaking, you can’t. According to the ssh spec:

A session is a remote execution of a program. The program may be a
shell, an application, a system command, or some built-in subsystem.

This means that, once the command has executed, the session is finished. You cannot execute multiple commands in one session. What you CAN do, however, is starting a remote shell (== one command), and interact with that shell through stdin etc… (think of executing a python script vs. running the interactive interpreter)

Method 4

You can do that by invoking shell on the client and sending commands. Please refer here
The page has code for python 3.5. I have modified the code a bit to work for pythin 2.7. Adding code here for reference

import threading, paramiko

strdata=''
fulldata=''

class ssh:
    shell = None
    client = None
    transport = None

    def __init__(self, address, username, password):
        print("Connecting to server on ip", str(address) + ".")
        self.client = paramiko.client.SSHClient()
        self.client.set_missing_host_key_policy(paramiko.client.AutoAddPolicy())
        self.client.connect(address, username=username, password=password, look_for_keys=False)
        self.transport = paramiko.Transport((address, 22))
        self.transport.connect(username=username, password=password)

        thread = threading.Thread(target=self.process)
        thread.daemon = True
        thread.start()

    def close_connection(self):
        if(self.client != None):
            self.client.close()
            self.transport.close()

    def open_shell(self):
        self.shell = self.client.invoke_shell()

    def send_shell(self, command):
        if(self.shell):
            self.shell.send(command + "n")
        else:
            print("Shell not opened.")

    def process(self):
        global strdata, fulldata
        while True:
            # Print data when available
            if self.shell is not None and self.shell.recv_ready():
                alldata = self.shell.recv(1024)
                while self.shell.recv_ready():
                    alldata += self.shell.recv(1024)
                strdata = strdata + str(alldata)
                fulldata = fulldata + str(alldata)
                strdata = self.print_lines(strdata) # print all received data except last line

    def print_lines(self, data):
        last_line = data
        if 'n' in data:
            lines = data.splitlines()
            for i in range(0, len(lines)-1):
                print(lines[i])
            last_line = lines[len(lines) - 1]
            if data.endswith('n'):
                print(last_line)
                last_line = ''
        return last_line


sshUsername = "SSH USERNAME"
sshPassword = "SSH PASSWORD"
sshServer = "SSH SERVER ADDRESS"


connection = ssh(sshServer, sshUsername, sshPassword)
connection.open_shell()
connection.send_shell('cmd1')
connection.send_shell('cmd2')
connection.send_shell('cmd3')
time.sleep(10)
print(strdata)    # print the last line of received data
print('==========================')
print(fulldata)   # This contains the complete data received.
print('==========================')
connection.close_connection()

Method 5

cmd = 'ls /home/dir'
self.ssh_stdin, self.ssh_stdout, self.ssh_stderr = self.ssh.exec_command(cmd)
print self.ssh_stdout.read()
cmd2 = 'cat /home/dir/test.log'
self.ssh_stdin2, self.ssh_stdout2, self.ssh_stderr2 = self.ssh.exec_command(cmd2)
print self.ssh_stdout2.read()

Method 6

You can run multiple command using the below technique. Use semicolon to separate the Linux commands
Eg:

chan.exec_command("date;ls;free -m")

Method 7

If you wish each command to have an effect on the next command you should use:

stdin, stdout, stderr = client.exec_command("command1;command2;command3")

but in some cases, I found that when “;” doesn’t work, using “&&” does work.

stdin, stdout, stderr = client.exec_command("command1 && command2 && command3")

Method 8

You can execute an entire BASH script file for better use, here is the code for that:

import paramiko

hostname = "192.168.1.101"
username = "test"
password = "abc123"

# initialize the SSH client
client = paramiko.SSHClient()
# add to known hosts
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
    client.connect(hostname=hostname, username=username, password=password)
except:
    print("[!] Cannot connect to the SSH Server")
    exit()

# read the BASH script content from the file
bash_script = open("script.sh").read()
# execute the BASH script
stdin, stdout, stderr = client.exec_command(bash_script)
# read the standard output and print it
print(stdout.read().decode())
# print errors if there are any
err = stderr.read().decode()
if err:
    print(err)
# close the connection
client.close()

This will execute the local script.sh file on the remote 192.168.1.101 Linux machine.

script.sh (just an example):

cd Desktop
mkdir test_folder
cd test_folder
echo "$PATH" > path.txt

This tutorial explains this in detail: How to Execute BASH Commands in a Remote Machine in Python.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0