I am running python3 in Windows 10. Within my program, I try to launch another python instance.
os.system("python -m http.server")
print("All Done")
or
os.system("python")
I want to see a Window shell that pops up and allow me the see the output and interact with it. But instead the program just continues. I don't even see a window pops up. What am I missing?
If you want to open a new window, you need to use start cmd
If you want to open a new window running a command from cmd, that's start cmd /c "command"
e.g
import os
os.system('start cmd /c "python -m http.server"')
However, if you really just want to run another python process, you can import and run the server directly from code - refer docs
I want another python script that I run on the main python script to run in a separate window. I found out that if I use start script.py from cmd, the script runs in a separate window, not in current terminal. So, I want to run the same from a python script, but there is no path to start.exe in sys.path. So where is this file located so I can add it to sys.path so that I can run scripts this way? Or can I run scripts in a separate window in other better ways?
Since start command is built in, to run it outside of cmd, including python scripts, we can use cmd /c start script.py. This works for me.
I'm fairly new to Python and I have a python script that I would like to ultimately convert to a Windows executable (which I already know how to do). Is there a way I can write something in the script that would make it run as a background process in Windows instead of being visible in the foreground?
You can always run a Windows program in the background using
START /B program
See this post for more information.
You can run the file using pythonw instead of python means run the command pythonw myscript.py instead of python myscript.py
I know how to set-up run configurations to pass parameters to a specific python script. There are several entry points, I don't want a run configuration for each one do I? What I want to do instead is launch a python script from a command line shell script and be able to attach the PyCharm debugger to the python script that is executed and have it stop at break points. I've tried to use a pre-launch condition of a utility python script that will sleep for 10 seconds so I can attempt to "attach to process" of the python script. That didn't work. I tried to import pdb and settrace to see if that would stop it for attaching to the process, but that looks to be command line debugging specific only. Any clues would be appreciated.
Thanks!
You can attach the debugger to a python process launched from terminal:
Use Menu Tools --> Attach to process then select python process to debug.
If you want to debug a file installed in site-packages you may need to open the file from its original location.
You can to pause the program manually from debugger and inspect the suspended Thread to find your source file.
I'd like to call a separate non-child python program from a python script and have it run externally in a new shell instance. The original python script doesn't need to be aware of the instance it launches, it shouldn't block when the launched process is running and shouldn't care if it dies. This is what I have tried which returns no error but seems to do nothing...
import subprocess
python_path = '/usr/bin/python'
args = [python_path, '&']
p = subprocess.Popen(args, shell=True)
What should I be doing differently
EDIT
The reason for doing this is I have an application with a built in version of python, I have written some python tools that should be run separately alongside this application but there is no assurance that the user will have python installed on their system outside the application with the builtin version I'm using. Because of this I can get the python binary path from the built in version programatically and I'd like to launch an external version of the built in python. This eliminates the need for the user to install python themselves. So in essence I need a simple way to call an external python script using my current running version of python programatically.
I don't need to catch any output into the original program, in fact once launched I'd like it to have nothing to do with the original program
EDIT 2
So it seems that my original question was very unclear so here are more details, I think I was trying to over simplify the question:
I'm running OSX but the code should also work on windows machines.
The main application that has a built in version of CPython is a compiled c++ application that ships with a python framework that it uses at runtime. You can launch the embedded version of this version of python by doing this in a Terminal window on OSX
/my_main_app/Contents/Frameworks/Python.framework/Versions/2.7/bin/python
From my main application I'd like to be able to run a command in the version of python embedded in the main app that launches an external copy of a python script using the above python version just like I would if I did the following command in a Terminal window. The new launched orphan process should have its own Terminal window so the user can interact with it.
/my_main_app/Contents/Frameworks/Python.framework/Versions/2.7/bin/python my_python_script
I would like the child python instance not to block the main application and I'd like it to have its own terminal window so the user can interact with it. The main application doesn't need to be aware of the child once its launched in any way. The only reason I would do this is to automate launching an external application using a Terminal for the user
If you're trying to launch a new terminal window to run a new Python in (which isn't what your question asks for, but from a comment it sounds like it's what you actually want):
You can't. At least not in a general-purpose, cross-platform way.
Python is just a command-line program that runs with whatever stdin/stdout/stderr it's given. If those happen to be from a terminal, then it's running in a terminal. It doesn't know anything about the terminal beyond that.
If you need to do this for some specific platform and some specific terminal program—e.g., Terminal.app on OS X, iTerm on OS X, the "DOS prompt" on Windows, gnome-terminal on any X11 system, etc.—that's generally doable, but the way to do it is by launching or scripting the terminal program and telling it to open a new window and run Python in that window. And, needless to say, they all have completely different ways of doing that.
And even then, it's not going to be possible in all cases. For example, if you ssh in to a remote machine and run Python on that machine, there is no way it can reach back to your machine and open a new terminal window.
On most platforms that have multiple possible terminals, you can write some heuristic code that figures out which terminal you're currently running under by just walking os.getppid() until you find something that looks like a terminal you know how to deal with (and if you get to init/launchd/etc. without finding one, then you weren't running in a terminal).
The problem is that you're running Python with the argument &. Python has no idea what to do with that. It's like typing this at the shell:
/usr/bin/python '&'
In fact, if you pay attention, you're almost certainly getting something like this through your stderr:
python: can't open file '&': [Errno 2] No such file or directory
… which is exactly what you'd get from doing the equivalent at the shell.
What you presumably wanted was the equivalent of this shell command:
/usr/bin/python &
But the & there isn't an argument at all, it's part of sh syntax. The subprocess module doesn't know anything about sh syntax, and you're telling it not to use a shell, so there's nobody to interpret that &.
You could tell subprocess to use a shell, so it can do this for you:
cmdline = '{} &'.format(python_path)
p = subprocess.Popen(cmdline, shell=True)
But really, there's no good reason to. Just opening a subprocess and not calling communicate or wait on it already effectively "puts it in the background", just like & does on the shell. So:
args = [python_path]
p = subprocess.Popen(args)
This will start a new Python interpreter that sits there running in the background, trying to use the same stdin/stdout/stderr as your parent. I'm not sure why you want that, but it's the same thing that using & in the shell would have done.
Actually I think there might be a solution to your problem, I found a useful solution at another question here.
This way subprocess.popen starts a new python shell instance and runs the second script from there. It worked perfectly for me on Windows 10.
You can try using screen command
with this command a new shell instance created and the current instance runs in the background.
# screen; python script1.py
After running above command, a new shell prompt will be seen where we can run another script and script1.py will be running in the background.
Hope it helps.