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

Question

I have Python script bgservice py and I want it to run all the time  because it is part of the web service I build  How can I make it run continuously even after I logout SSH

User · Answer

Try this  nohup python -u  lt your file name gt  py  gt  gt   lt your log file gt  log  amp   You can run above command in screen and come out of screen  Now you can tail logs of your python script by  tail -f  lt your log file gt  log To kill you script  you can use ps -aux and kill commands

User · Answer

You can also use Yapdi   Basic usage    import yapdi  daemon   yapdi Daemon   retcode   daemon daemonize      This would run in daemon mode  output is not visible if retcode    yapdi OPERATION SUCCESSFUL  print  Hello Daemon

User · Answer

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  amp  so the script runs in the background  nohup  path to test py  amp   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  amp   The output will be saved in the nohup out file  unless you specify the output file like here  nohup  path to test py  gt  output log  amp  nohup python  path to test py  gt  output log  amp   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  gt  dev null 2 gt  amp 1     If you re using nohup  that probably means you want to run the command in the background by putting another  amp  on the end of the whole thing    runs in background  still doesn t create nohup out   nohup command  gt  dev null 2 gt  amp 1  amp     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

User · Answer

You might consider turning your python script into a proper python daemon  as described here   python-daemon is a good tool that can be used to run python scripts as a background daemon process rather than a forever running script  You will need to modify existing code a bit but its plain and simple    If you are facing problems with python-daemon  there is another utility supervisor that will do the same for you  but in this case you wont have to write any code  or modify existing  as this is a out of the box solution for daemonizing processes

User · Answer

Here is a simple solution inside python using a decorator   import os  time  def daemon func       def wrapper  args    kwargs           if os fork    return         func  args    kwargs          os  exit os EX OK      return wrapper   daemon def my func count 10         for i in range 0 count        print  parent pid   d    os getppid         time sleep 1    my func count 10   still in parent thread time sleep 2   after 2 seconds the function my func lives on is own   You can of course replace the content of your bgservice py file in place of my func

User · Answer

The zsh shell has an option to make all background processes run with nohup   In    zshrc add the lines   setopt nocheckjobs   don t warn about bg processes on exit setopt nohup         don t kill bg processes on exit   Then you just need to run a process like so  python bgservice py  amp   and you no longer need to use the nohup command   I know not many people use zsh  but it s a really cool shell which I would recommend

User · Answer

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

User · Answer

If what you need is that the process should run forever no matter whether you are logged in or not  consider running the process as a daemon    supervisord is a great out of the box solution that can be used to daemonize any process  It has another controlling utility supervisorctl that can be used to monitor processes that are being run by supervisor    You don t have to write any extra code or modify existing scripts to make this work  Moreover  verbose documentation makes this process much simpler   After scratching my head for hours around python-daemon  supervisor is the solution that worked for me in minutes   Hope this helps someone trying to make python-daemon work

User · Answer

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

User · Answer

You can nohup it  but I prefer screen

User · Answer

Run nohup python bgservice py  amp  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

[python] How to run a Python script in the background even after I logout SSH?

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