I am writing a program in python on Ubuntu, to execute a command ls -l on RaspberryPi, connect with Network.
Can anybody guide me on how do I do that?
Sure, there are several ways to do it!
Let's say you've got a Raspberry Pi on a raspberry.lan host and your username is irfan.
It's the default Python library that runs commands.
You can make it run ssh and do whatever you need on a remote server.
scrat has it covered in his answer. You definitely should do this if you don't want to use any third-party libraries.
You can also automate the password/passphrase entering using pexpect.
paramiko is a third-party library that adds SSH-protocol support, so it can work like an SSH-client.
The example code that would connect to the server, execute and grab the results of the ls -l command would look like that:
import paramiko
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('raspberry.lan', username='irfan', password='my_strong_password')
stdin, stdout, stderr = client.exec_command('ls -l')
for line in stdout:
print line.strip('\n')
client.close()
You can also achieve it using fabric.
Fabric is a deployment tool which executes various commands on remote servers.
It's often used to run stuff on a remote server, so you could easily put your latest version of the web application, restart a web-server and whatnot with a single command. Actually, you can run the same command on multiple servers, which is awesome!
Though it was made as a deploying and remote management tool, you still can use it to execute basic commands.
# fabfile.py
from fabric.api import *
def list_files():
with cd('/'): # change the directory to '/'
result = run('ls -l') # run a 'ls -l' command
# you can do something with the result here,
# though it will still be displayed in fabric itself.
It's like typing cd / and ls -l in the remote server, so you'll get the list of directories in your root folder.
Then run in the shell:
fab list_files
It will prompt for an server address:
No hosts found. Please specify (single) host string for connection: irfan@raspberry.lan
A quick note: You can also assign a username and a host right in a fab command:
fab list_files -U irfan -H raspberry.lan
Or you could put a host into the env.hosts variable in your fabfile. Here's how to do it.
Then you'll be prompted for a SSH password:
[irfan@raspberry.lan] run: ls -l
[irfan@raspberry.lan] Login password for 'irfan':
And then the command will be ran successfully.
[irfan@raspberry.lan] out: total 84
[irfan@raspberry.lan] out: drwxr-xr-x 2 root root 4096 Feb 9 05:54 bin
[irfan@raspberry.lan] out: drwxr-xr-x 3 root root 4096 Dec 19 08:19 boot
...