Windows Batch start python script with pipe

Question

I'm trying to create a batch script or scheduled task that can run this:

pythonw manage.py runserver >nul

This will run if I wrote it from a command prompt, and return me the prompt, but if I try to run it using a batch file or an scheduled task it will open a window and lock itself in that command. The window I will close adding a final "exit" but it will be locked in the first command unless I kill the process in the task manager.

How can I do this? if it works in the normal cmd why don't work the same way when in a .bat or .cmd file?

I don't know python, but pythonw is a GUI program therefore has no access to the console that starts it. Therefore the >nul is meaningless. However your specific problem is something else - in a batch CMD waits for GUI programs to exit (interactively CMD only waits for console programs). See start /? for help on this (it explains starting programs with and without using start - new behaviour is from Windows 2000 compared with Windows NT4). You probably should be using python, however see start /w if you want to use the GUI python in a console it's not designed for. — user6017774
– user6017774, Commented May 31, 2016 at 11:51
The part with >nul is because manage.py is a django script that is not meant to run in this way and uses the stdout in every action you perform with the webserver it creates. This is a workaround to make the Django dev server start on startup w/o console and no log just to hardcore testing. — fdzworkzone
– fdzworkzone, Commented May 31, 2016 at 11:55

fdzworkzone · Accepted Answer · 2016-05-31 12:01:53Z

2

Ok, after testing more and more I found something that works. Sorry for making the Question without searching and testing more.

This is what has worked:

CMD /c start "" /B path\to\pythonw.exe path\to\manage.py runserver > nul ^& exit

Inside a .cmd file. Executing the file starts the Django dev webserver properly and a scheduled task that runs that .cmd file also start the server.

answered May 31, 2016 at 12:01

fdzworkzone

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2 Comments

Eryk Sun Over a year ago

What happens if you just use start "" /B path\to\pythonw.exe path\to\manage.py runserver > nul? The /B is required to force cmd.exe to set the stdout handle, but why would you need cmd /c ... ^& exit? pythonw.exe doesn't use the console, so there shouldn't be a problem; the batch should just continue and exit. start "" /B pythonw.exe -c "import time;time.sleep(60)" >nul works fine for me. And if I attach a debugger I can see that @$peb->ProcessParameters->StandardOutput is the nul device, while StandardInput and StandardError are unset as NULL.

fdzworkzone Over a year ago

Well, I don't really know why I need that, but what I know is that without it when I launched this it would open a command window and not close it unless I do it by hand. Also, de problem is because the way manage.py works

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