从python运行nohup和eval

Question

I need run two commands (from shell looks like)

$ eval `ssh-agent -s`
Agent pid 8631
$ ssh-add ~/.ssh/user

Note : The key is in /home/user/.ssh/user and is correct

Run is as bash script works as charm:

#!/bin/bash
nohup `eval `ssh-agent -s`` >/dev/null 2>&1 &
ssh-add ~/.ssh/$user

but from python I can't get working, ssh-agent is started but ssh-add returns:
Could not open a connection to your authentication agent.

import os
os.system('nohup \'eval `ssh-agent -s`\' &')
os.system('ssh-add /home/user/.ssh/user')

I've tried:

import os
system('nohup sh -c \'eval `ssh-agent -s`\' &')

same problem ssh-agent started, but somehow I can't connected

Answer 1

What os.system does it to launch a different shell for each command. And what eval `ssh-agent -s` does is to launch a new ssh-agent and store in current shell some environment variables needed to communicate with it. Finally, ssh-add uses that variables to access the ssh-agent agent to add a new key to it.

So you need to execute both commands on the same shell. You can do this with a unique call to os.system calling both commands sequentially:

os.system("eval `ssh-agent -s`; ssh-add /home/user/.ssh/user")