How to send control signals using paramiko in python?

问题

I have a code snippet something like this:

ssh = paramiko.SSHClient()
ssh.load_system_host_keys()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(ip,port=Port, username=usr,password=Psw)
stdin, stdout, stderr= ssh.exec_command("watch -n1 ps")
print stdout.read(),stderr.read()

The problem here is I have to run watch or any infinitely running command for 10 seconds and after that I should send SIGINT(Ctrl + c) and print the status.

How do I do that?

回答1:

One way to get around this would be to open your own session, pseudo-terminal, and then read in a non-blocking fashion, using recv_ready() to know when to read. After 10 seconds, you send ^C (0x03) to terminate the running process and then close the session. Since you're closing the session anyway, sending ^C is optional, but it may be useful if you want to keep the session alive and run commands multiple times.

import paramiko
import time
import sys

ssh = paramiko.SSHClient()
ssh.load_system_host_keys()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(ip, port=Port, username=usr,password=Psw)

transport = ssh.get_transport()
session = transport.open_session()
session.setblocking(0) # Set to non-blocking mode
session.get_pty()
session.invoke_shell()

# Send command
session.send('watch -n1 ps\n')

# Loop for 10 seconds
start = time.time()    
while time.time() - start < 10:
  if session.recv_ready():
    data = session.recv(512)

    sys.stdout.write(data)
    sys.stdout.flush() # Flushing is important!

  time.sleep(0.001) # Yield CPU so we don't take up 100% usage...

# After 10 seconds, send ^C and then close
session.send('\x03')
session.close()
print

回答2:

The only way to transport signals is via terminal, from ssh man:

  -t   Force pseudo-tty allocation.  This can be used to execute
       arbitrary screen-based programs on a remote machine, which can be
       very useful, e.g. when implementing menu services.  Multiple -t
       options force tty allocation, even if ssh has no local tty.

For paramiko check: http://docs.paramiko.org/en/1.16/api/channel.html

get_pty(*args, **kwds)
Request a pseudo-terminal from the server. This is usually used right after creating a client channel, to ask the server to provide
some basic terminal semantics for a shell invoked with invoke_shell. It isn’t necessary (or desirable) to call this method if you’re going to exectue a single command with exec_command.

来源：https://stackoverflow.com/questions/33910308/how-to-send-control-signals-using-paramiko-in-python

标签

python

paramiko