How to exit python subprocess if it fails

Question

I am reading some output of remote server using SSH bash(command). I need to do it constantly, so I spawn subprocess. It works fine, unless server server become unavailable for brief period. How do I restart SSH command (whole subprocess) if it fails?

I have following piece of code:

(...)

process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, universal_newlines=True)
while True:
    line = process.stdout.readline()
    if lines == "" and process.poll() is not None:
        break
(...)

I would think that process.poll() is not None should do the trick but it seems to hang on

1000     21431  0.0  0.0      0     0 pts/0    Z+   Oct22   0:00 [ssh] <defunct>

And does not break out of while True:

Just put the entire block into another while True as well? — MisterMiyagi
– MisterMiyagi, Commented Oct 26, 2020 at 9:05
the problem is that the ssh process inside goes to [ssh] <defunct> state and process.stdout.readline() waits forever. I would like to break out of readline() when ssh disconnects... — Wojtas.Zet
– Wojtas.Zet, Commented Oct 28, 2020 at 9:03

Wojtas.Zet · Accepted Answer · 2020-10-28 12:11:16Z

4

I had silly typo error in my code preventing if lines == "" and process.poll() is not None: from executing properly. Another thing to look at is ssh_config, It is wise to set values to disconnect @60 seconds/1 attempt. And avoid process.communicate() as it is blocking the whole thread.

answered Oct 28, 2020 at 12:11

Wojtas.Zet

8263 gold badges16 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to exit python subprocess if it fails

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related