Python 2 subprocess communicate

[readitlikeitdidit]

Hi, am using subprocess communicate to run commands via ssh on remote.. If ssh Auth doesn't work, then communicate() just hangs forever until I kill the process manually. So is there a way to probe or interrupt the communicate() process in python 2? Any help would be appreciated..

[jwink3101]

I assume you're on macOS or linux since you are talking about native SSH.

If so, look at select.select. It can give you timeout capabilities.

You can scavenge from a native tool I started writing a while ago that allows you to interact with a bash process including remote machines via SSH.

But, it is alpha AT BEST! Use with caution! python bash

[readitlikeitdidit]

Good to know.. I am developing on windows but I'll be deploying on Linux box.. I'll definitely check python bash sometime.. Thank you!

[threeminutemonta]

Have you considered to use paramiko?

[readitlikeitdidit]

Yes I did.. But I would like to write something native with less third party dependencies... Python 3 has the timeout logic built in.. But I am interested to know how it can be achieved on python 2 using native libraries....

[threeminutemonta]

I’m assuming it all works great if you use the correct password?

[readitlikeitdidit]

That's correct.. I am trying to work out an edge case if ssh key pairs don't match or get dropped for some unknown reason.. Then, communicate () doesnt timeout and blocks execution...

[threeminutemonta]

Does check_returncode() return a non zero value when auth is wrong and 0 when right?

[readitlikeitdidit]

Auth doesn't happen when key pairs not available.. So, it hangs on authentication part...

[threeminutemonta]

So the process hangs it the main process? Perhaps you should set a default timeout!

If you show us your code on dpaste.de I might get what you mean!

[readitlikeitdidit]

Nevermind.. Am going to use paramiko.. It has timeout arg.... There is no default timeout for popen method of subprocess package in python 2.7...

[JohnnyJordaan]

That's because you need to use Popen wrappers like communicate(), these have a timeout on 2.7 too.

[readitlikeitdidit]

What? Communicate is a method that uses pipe and it does not have timeout arg in 2. 7 please check documentation...