How to run a script in the background even after I logout SSH?

Run nohup python bgservice.py & to get the script to ignore the hangup signal and keep running. Output will be put in nohup.out.

Ideally, you'd run your script with something like supervise so that it can be restarted if (when) it dies.

If you've already started the process, and don't want to kill it and restart under nohup, you can send it to the background, then disown it.

Ctrl+Z (suspend the process)

bg (restart the process in the background

disown %1 (assuming this is job #1, use jobs to determine)

Running a Python Script in the Background

First, you need to add a shebang line in the Python script which looks like the following:

#!/usr/bin/env python3

This path is necessary if you have multiple versions of Python installed and /usr/bin/env will ensure that the first Python interpreter in your $$PATH environment variable is taken. You can also hardcode the path of your Python interpreter (e.g. #!/usr/bin/python3), but this is not flexible and not portable on other machines. Next, you’ll need to set the permissions of the file to allow execution:

chmod +x test.py

Now you can run the script with nohup which ignores the hangup signal. This means that you can close the terminal without stopping the execution. Also, don’t forget to add & so the script runs in the background:

nohup /path/to/test.py &

If you did not add a shebang to the file you can instead run the script with this command:

nohup python /path/to/test.py &

The output will be saved in the nohup.out file, unless you specify the output file like here:

nohup /path/to/test.py > output.log &
nohup python /path/to/test.py > output.log &

If you have redirected the output of the command somewhere else - including /dev/null - that's where it goes instead.

# doesn't create nohup.out

nohup command >/dev/null 2>&1   

If you're using nohup, that probably means you want to run the command in the background by putting another & on the end of the whole thing:

# runs in background, still doesn't create nohup.out

 nohup command >/dev/null 2>&1 &  

You can find the process and its process ID with this command:

ps ax | grep test.py

# or
# list of running processes Python

ps -fA | grep python

ps stands for process status

If you want to stop the execution, you can kill it with the kill command:

kill PID

You could also use GNU screen which just about every Linux/Unix system should have.

If you are on Ubuntu/Debian, its enhanced variant byobu is rather nice too.