通过SSH在两台计算机之间传输文件

Question

I have two computers(lets name them A and B) with linux (two raspberry pi 3 ). I need to get file from B and see it on A. So I connected them with ssh.

B code file contains:

import rospy
from clever import srv
rospy.init_node('telemetry')  
file = open("telemetry", "w+")
while True:
  get_telemetry = rospy.ServiceProxy('get_telemetry', srv.GetTelemetry) 
  position = get_telemetry(frame_id='aruco_map')
  f.write(get_telemetry)

call here a rospy Service Proxy,then write
necessary info into the file "telemetry",which I created on both raspberries.This part works fine.

Code file on A contains

import subprocess
while True:
  subprocess.call(["ssh","pi@B", "'cat telemetry'", ">", "telemetry"])

B is raspbbery ip and pi is login

But when i run code file on A it says "bash: cat telemetry: command not found" What am I doing wrong? Thanks for help.

Answer 1

When using subprocess.call , you don't need to add extra quotes because spaces are not delimiters. Also, since the shell is not involved locally, output redirection with > doesn't work. The > will be sent to remote host and will run remotely. To redirect the actual local command to a file, you must use subprocess PIPE output capturing by passing a parameter named stdout :

with open('telemetry', 'wb') as f:
    subprocess.call(["ssh", "pi@B", "cat telemetry"], stdout=f)

That should fix your issue and answer your question "What am I doing wrong?" - however, as others have pointed out in the comments, you should consider using scp , sshfs or even a paramiko session instead of running a remote cat to copy files.

Answer 2

May I suggest using Python Fabric ( HERE ). It's very easy to configure. You just make a connection a call a function:

from fabric import Connection
C = fabric.Connection('IP', user='pi', connect_kwargs={"password": "raspberry"})
result = C.put('myfile', remote='/home/pi')

I use it for the same thing.