Running a subprocess in a venv

[Johannes Findeisen]

On Sat, 21 Oct 2023 11:32:03 -0400
Larry Martell <larry.martell at gmail.com> wrote:

> On Sat, Oct 21, 2023 at 9:49 AM Johannes Findeisen
> <mailman at hanez.org> wrote:
> >
> > On Sat, 21 Oct 2023 09:01:18 -0400
> > Larry Martell via Python-list <python-list at python.org> wrote:
> >
> > > I have a python script, and from that I want to run another
> > > script in a subprocess in a venv. What is the best way to do
> > > that? I could write a file that activates the venv then runs the
> > > script, then run that file, but that seems messy. Is there a
> > > better way?
> >
> > How do you do that?
> 
> How? Open a file and write the commands I need then invoke that.
> 
> > It sounds messy but not wrong...
> >
> > I would activate the venv and then run my Python script. In the
> > Python script you can call another python script in a subprocess
> > like this:
> >
> > import sys
> > import subprocess
> >
> > #
> > https://docs.python.org/3/library/subprocess.html#popen-constructor
> > proc = subprocess.Popen([sys.executable,
> > "/path/to/an/otherscript.py"])
> >
> > # https://docs.python.org/3/library/subprocess.html#popen-objects
> > # Do your process communication/handling... proc.communicate(),
> > # proc.wait(), proc.terminate(), proc.kill() etc.
> >
> > Is this the answer you are looking for?
> >
> > Detailed docs: https://docs.python.org/3/library/subprocess.html
> 
> I know how to use Popen. What I was missing was running the script
> using sys.executable. Thanks.

sys.executable is the path to the actual Python binary, e.g.
"/usr/bin/python". You could add "/usr/bin/python" there manually but
this is not portable to Windows for example.

When you add a shebang line to your other script and the file is
executable, you may not need to add sys.executable as first argument to
Popen but using sys.executable is the most reliable way to do this... ;)

Regards,
Johannes