如何从 python 脚本激活虚拟环境并在其中执行进一步的指令？

Question

Here's what I would like to do with my Python script:

1. Create virtual environment
2. Change directory into environment
3. Activate environment
4. Install django
5. Do other stuff...

I've managed to create the environment and change directory with the following:

import subprocess
import os

env_name = "env_new"
subprocess.run(["py", "-m", "venv", env_name])
chdir(env_name)

But activating the environment is a different story:

subprocess.run(["source", "./Scripts/activate"])  # Also tried with activate.bat

Result:

FileNotFoundError: [WinError 2] The system cannot find the file specified

subprocess.run([".", "./Scripts/activate"])  # Also tried with activate.bat

Result:

PermissionError: [WinError 5] Access is denied

Just to clarify, I made sure I was in the correct directory by using print(os.getcwd()).

After this I'd then like to install django. I think it has to happen inside the same run() method like so:

subprocess.run([".", "./Scripts/activate", "&&", "pip", "install", "django"])  # Or something...

Is this even possible?

Answer 1

There is a number of things wrong here. When you run a subprocess, the environment it creates disappears when the subprocess exits.

What you can do is wrap Python inside Python, something like

import subprocess

env_name = "env_new"
subprocess.run(["py", "-m", "venv", env_name])

subprocess.run(["%s/bin/python" % env_name, "-c", """
    the rest of your Python code here
    """])

which of course is just a rather pointless complication, and better written as a shell script.

#!/bin/bash

py -m venv env_new
. ./env_new/Scripts/activate
pip install -r requirements.txt
python ./your_real_script_here.py

Answer 2

Original poster here. I just want to expand on triplee 's answer above by displaying the full code required to achieve my desired result.

Python Script #1 - django-setup

#!/usr/bin/env python
import subprocess
import sys

if __name__ == '__main__':
    if len(sys.argv) > 1:
        subprocess.call(f"intermediary.sh {sys.argv[1]}", shell=True)
    else:
        print("No arguments given")

Shell Script - intermediary.sh

#!/bin/bash

py -m venv "env_$1"
cd "env_$1"
. ./Scripts/activate
pip install django
mkdir "$1"
cd "$1"
django-setup-2

Python Script #2 - django-setup-2

#!/usr/bin/env python

import subprocess

subprocess.run(['django-admin', 'startproject', 'config', '.'])
print("More code here!")

Executing the command django-setup blog would achieve the following result:

env_blog/
    Scripts/
    Include/
    Lib/
    blog/
        config/
        manage.py
    pyvenv.cfg

Answer 3

1. For the creation of a virtual environment and using it, follow here .

2. Alternatively, you may use Conda to create and manage your virtual environments.