Develop Reference

How to use os.system (or alternative) to remotely shutdown any system?

I am trying to use the call below to shut down my system, but I would like it to work on all major OS distro's. Is there a catch all shutdown command?
import os
os.system("shutdown /s /t 1")
Is there any other way to shutdown a machine remotely through python code?

For managing nodes remotely, ansible is a very nice tool, with gather facts you can get the current node os, then conditionally shut down accordingly.

Following function provides portable way of sending commands to remote host:
def run_shell_remote_command(remote_host, remote_cmd, pem_file=None, ignore_errors=False):
remote_cmd = remote_cmd.split(' ')
cmd = [SSH_PATH, '-o ConnectTimeout=30', '-o BatchMode=yes', '-o StrictHostKeyChecking=no']
if pem_file:
cmd.extend(['-i', pem_file])
cmd.extend([remote_host] + remote_cmd)
print(f"SSH CMD: {cmd}")
p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
stdout, stderr = p.communicate()
if p.returncode != 0:
if not ignore_errors:
raise RuntimeError("%r failed, status code %s stdout %r stderr %r" % (
remote_cmd, p.returncode, stdout, stderr))
return stdout.strip() # This is the stdout from the shell command
That way you can run any command on remote host, which are supported by remote OS.

Cannot get subprocess output in Django view

I want to emulate command line call of my script (TensorFlow neaural chatbot model) in Django view and get output from console to variable.
When i do manually in terminal of my server:
python3 var/www/engine/chatbot/udc_predict.py --model_dir=var/www/engine/chatbot/runs/1486057482/
the output is good and printed out.
So in my Django view i do:
import subprocess
answer = subprocess.check_output(['python3', 'var/www/engine/chatbot/udc_predict.py','--model_dir=var/www/engine/chatbot/runs/1486057482/'], shell=True, stderr=subprocess.STDOUT, timeout=None)
print('answer', answer)
And answer variable is printed as b'' in Apache error log.
I cannot figure out what's wrong in my call.

The answer is to use .communicate() and PIPE:
from subprocess import Popen, PIPE
proc = Popen(
"python3 var/www/engine/chatbot/udc_predict.py --model_dir=var/www/engine/chatbot/runs/1486057482/",
shell=True,
stdout=PIPE, stderr=PIPE
)
proc.wait()
res = proc.communicate()
if proc.returncode:
print(res[1])
print('result:', res[0])
answer = res[0]

How to send the password after user name in command prompt using python

Trying to run some windows application in a specific user mode. After passing the command, it will ask for password. So passing the password using proc.communicate() but its not working, Please help
from subprocess import Popen, PIPE
import time
cmd = "runas /user:administrator notepad.exe"
proc = Popen(cmd, stdout=PIPE, stdin=PIPE, stderr=PIPE)
print proc.stdout.read()
proc.communicate('password')

Are you open to using Pexpect instead? If yes, you can use the following:
import pexpect
cmd = "runas /user:administrator notepad.exe"
child_process = pexpect.spawn(cmd)
child_process.expect('assword')
child_process.sendline(password)

open a putty window and run ssh commands - Python

I am new to python. I need to login to a server daily (Desktop -> 1.32 -> 0.20 -> 3.26). For this I need to open putty and using ssh connection i am logging in. To do all this I want to write a script using python.
By using google I thought subprocess.Popen will do that. But Its not working fine.
1st trail:
import subprocess
pid = subprocess.Popen("putty.exe user#xxx.xx.x.32 -pw password").pid
Its working fine (Opening window logging into .32). But cant able to give input. I came to know that to give input for the same process we need to use pipes.
2nd trail:
from subprocess import Popen, PIPE, STDOUT
p = Popen("putty.exe user#xxx.xx.x.32 -pw password", stdout=PIPE, stdin=PIPE, stderr=STDOUT)
grep_stdout = p.communicate(input=b'ssh xx.xx.x.20\n')[0]
print(grep_stdout.decode())
by using this i cant login for the first server also. After logging in to all servers I need the terminal as alive. how to do this???
Edit
I need to do this in a new putty window. After logging in dont close the window. I have some manual work to do.

use powershell to call putty in order to open a new window
from subprocess import Popen
Popen("powershell putty.exe user#host -pw mypassword")

Use paramiko library python
Establish a SSH connection using -
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(hostname,username, password)
Check the status if connection is alive using -
status = ssh.get_transport().is_active()
#returns True if connection is alive/active
ssh.exec_command() is basically a single session. Use exec_command(command1;command2) to execute multiple commands in one session
Also, you can use this to execute multiple commands in single session
channel = ssh.invoke_shell()
stdin = channel.makefile('wb')
stdout = channel.makefile('rb')
stdin.write('''
Command 1
Command 2
''')
print stdout.read()

There is a SSHv2 protocol implementation for python: http://www.paramiko.org/. You can easily install it with pip:
pip install paramiko
Then you can create ssh client, connect to your host and execute commands:
import paramiko
ssh_client = paramiko.SSHClient()
ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh_client.connect('hostname', username='login', password='pwd')
stdin, stdout, stderr = ssh_client.exec_command('command')

I created a bat file on windows, which references putty and putty session-specific info. This bat file can run by itself on windows. To call from python, I used the subprocess.run() -- python 3.5+.
Example of bat file named putty.bat:
start c:\app\PuTTy\putty.exe -load 192.168.1.230-node1-logs -l <logon user> -pw <logon user password for putty session>
Breaking down the bat file:
It begins with window's command "start".
c:\app\PuTTy\putty.exe --> is the putty directory on Windows containing putty.exe.
-load --> tells putty to load a putty profile. The profile is the name you see on the putty client, under "Saved Sessions".
192.168.1.230-node1-logs --> my putty session specific profile.
-l for logon --> followed by the putty logon user.
-pw is the logon password --> followed by the putty logon password.
That concludes the contents of "putty.bat".
From within python, is used the subprocess.run() command.
Example:
import subprocess
...
...
try:
process = subprocess.run(["putty.bat"], check=True, stdout=subprocess.PIPE, universal_newlines=True)
print(process.stdout)
except Exception as e:
print("subprocess call error in open putty command")
print(str(e))
I hope you find this helpful

How do I execute Cassandra CLI commands from a Python script?

I have a python script that I want to use to make remote calls on a server, connect to Cassandra CLI, and execute commands to create keyspaces. One of the attempts that I made was something to this effect:
connect="cassandra-cli -host localhost -port 1960;"
create_keyspace="CREATE KEYSPACE someguy;"
exit="exit;"
final = Popen("{}; {}; {}".format(connect, create_keyspace, exit), shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
stdout, nothing = final.communicate()
Looking through various solutions, I'm not finding what I need. For example, the above code is throwing a "/bin/sh: 1: CREATE: not found", which I think means that it's not executing the CREATE statement on the CLI command line.
Any/all help would be GREATLY appreciated! Thank you!

try this out. I don't have cassandra-cli installed on my machine, so I couldn't test it myself.
from subprocess import check_output
from tempfile import NamedTemporaryFile
CASSANDRA_CMD = 'cassandra-cli -host localhost -port 1960 -f '
def cassandra(commands):
with NamedTemporaryFile() as f:
f.write(';\n'.join(commands))
f.flush()
return check_output(CASSANDRA_CMD + f.name, shell=True)
cassandra(['CREATE KEYSPACE someguy', 'exit'])
As you mentioned in the comment below pycassa a Python client for Cassandra cannot be used since it doesn't seem to support create statements.