Develop Reference

Activate virtual environment and run command with single call to subprocess.Popen with shell=False possible? [duplicate]

I want to activate a virtualenv instance from a Python script.
I know it's quite easy to do, but all the examples I've seen use it to run commands within the env and then close the subprocess.
I simply want to activate the virtualenv and return to the shell, the same way that bin/activate does.
Something like this:
$me: my-script.py -d env-name
$(env-name)me:
Is this possible?
Relevant:
virtualenv › Invoking an env from a script

If you want to run a Python subprocess under the virtualenv, you can do that by running the script using the Python interpreter that lives inside virtualenv's /bin/ directory:
import subprocess
# Path to a Python interpreter that runs any Python script
# under the virtualenv /path/to/virtualenv/
python_bin = "/path/to/virtualenv/bin/python"
# Path to the script that must run under the virtualenv
script_file = "must/run/under/virtualenv/script.py"
subprocess.Popen([python_bin, script_file])
However, if you want to activate the virtualenv under the current Python interpreter instead of a subprocess, you can use the activate_this.py script:
# Doing execfile() on this file will alter the current interpreter's
# environment so you can import libraries in the virtualenv
activate_this_file = "/path/to/virtualenv/bin/activate_this.py"
execfile(activate_this_file, dict(__file__=activate_this_file))

The simplest solution to run your script under virtualenv's interpreter is to replace the default shebang line with path to your virtualenv's interpreter like so at the beginning of the script:
#!/path/to/project/venv/bin/python
Make the script executable:
chmod u+x script.py
Run the script:
./script.py
Voila!

It turns out that, yes, the problem is not simple, but the solution is.
First I had to create a shell script to wrap the "source" command. That said I used the "." instead, because I've read that it's better to use it than source for Bash scripts.
#!/bin/bash
. /path/to/env/bin/activate
Then from my Python script I can simply do this:
import os
os.system('/bin/bash --rcfile /path/to/myscript.sh')
The whole trick lies within the --rcfile argument.
When the Python interpreter exits it leaves the current shell in the activated environment.
Win!

To run another Python environment according to the official Virtualenv documentation, in the command line you can specify the full path to the executable Python binary, just that (no need to active the virtualenv before):
/path/to/virtualenv/bin/python
The same applies if you want to invoke a script from the command line with your virtualenv. You don't need to activate it before:
me$ /path/to/virtualenv/bin/python myscript.py
The same for a Windows environment (whether it is from the command line or from a script):
> \path\to\env\Scripts\python.exe myscript.py

Just a simple solution that works for me. I don't know why you need the Bash script which basically does a useless step (am I wrong ?)
import os
os.system('/bin/bash --rcfile flask/bin/activate')
Which basically does what you need:
[hellsing#silence Foundation]$ python2.7 pythonvenv.py
(flask)[hellsing#silence Foundation]$
Then instead of deactivating the virtual environment, just Ctrl + D or exit. Is that a possible solution or isn't that what you wanted?

The top answer only works for Python 2.x
For Python 3.x, use this:
activate_this_file = "/path/to/virtualenv/bin/activate_this.py"
exec(compile(open(activate_this_file, "rb").read(), activate_this_file, 'exec'), dict(__file__=activate_this_file))
Reference: What is an alternative to execfile in Python 3?

The child process environment is lost in the moment it ceases to exist, and moving the environment content from there to the parent is somewhat tricky.
You probably need to spawn a shell script (you can generate one dynamically to /tmp) which will output the virtualenv environment variables to a file, which you then read in the parent Python process and put in os.environ.
Or you simply parse the activate script in using for the line in open("bin/activate"), manually extract stuff, and put in os.environ. It is tricky, but not impossible.

For python2/3, Using below code snippet we can activate virtual env.
activate_this = "/home/<--path-->/<--virtual env name -->/bin/activate_this.py" #for ubuntu
activate_this = "D:\<-- path -->\<--virtual env name -->\Scripts\\activate_this.py" #for windows
with open(activate_this) as f:
code = compile(f.read(), activate_this, 'exec')
exec(code, dict(__file__=activate_this))

I had the same issue and there was no activate_this.py in the Scripts directory of my environment.
activate_this.py
"""By using execfile(this_file, dict(__file__=this_file)) you will
activate this virtualenv environment.
This can be used when you must use an existing Python interpreter, not
the virtualenv bin/python
"""
try:
__file__
except NameError:
raise AssertionError(
"You must run this like execfile('path/to/active_this.py', dict(__file__='path/to/activate_this.py'))")
import sys
import os
base = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
if(sys.platform=='win32'):
site_packages = os.path.join(base, 'Lib', 'site-packages')
else:
site_packages = os.path.join(base, 'lib', 'python%s' % sys.version[:3], 'site-packages')
prev_sys_path = list(sys.path)
import site
site.addsitedir(site_packages)
sys.real_prefix = sys.prefix
sys.prefix = base
# Move the added items to the front of the path:
new_sys_path = []
for item in list(sys.path):
if item not in prev_sys_path:
new_sys_path.append(item)
sys.path.remove(item)
sys.path[:0] = new_sys_path
Copy the file to the Scripts directory of your environment and use it like this:
def activate_virtual_environment(environment_root):
"""Configures the virtual environment starting at ``environment_root``."""
activate_script = os.path.join(
environment_root, 'Scripts', 'activate_this.py')
execfile(activate_script, {'__file__': activate_script})
activate_virtual_environment('path/to/your/venv')
Refrence: https://github.com/dcreager/virtualenv/blob/master/virtualenv_support/activate_this.py

You should create all your virtualenvs in one folder, such as virt.
Assuming your virtualenv folder name is virt, if not change it
cd
mkdir custom
Copy the below lines...
#!/usr/bin/env bash
ENV_PATH="$HOME/virt/$1/bin/activate"
bash --rcfile $ENV_PATH -i
Create a shell script file and paste the above lines...
touch custom/vhelper
nano custom/vhelper
Grant executable permission to your file:
sudo chmod +x custom/vhelper
Now export that custom folder path so that you can find it on the command-line by clicking tab...
export PATH=$PATH:"$HOME/custom"
Now you can use it from anywhere by just typing the below command...
vhelper YOUR_VIRTUAL_ENV_FOLDER_NAME
Suppose it is abc then...
vhelper abc

How can I change the default python3 path in MAC cmd?

My Mac has contained multiple python versions so that I would like to fix one as my default python.
In the current, it has set the path of anaconda python. I have stopped to use the anaconda-python.
And I would like to change the python3 as default following with path:
/usr/local/bin/python3
How can I do this?
Hope:
python3 as default that path
jupyter notebook would follow that path
pip3 install package would follow that path

Update your environment variable PATH to include your required python path. Append the python path in the beginning of the environment variable PATH, so that first it'll look in that path.
You need to update that in .bash_profile file. For that go to the root path and look for the mentioned file. Run ls-a to check whether the file is present.
cd ~
ls -a
Open the file
vi .bash_profile
Add below commands in the file (press i to go into insert mode)
# Setting PATH for Python
export PATH={ur path}:$PATH
(Save the file by pressing :wq)
Check whether the update is made by running
echo $PATH

You can change the path to this by editing the .bashrc file
export PATH="/usr/local/bin/python3:${PATH}"

How to add new default packages to virtualenv?

When I create a virtualenv, it installs setuptools and pip. Is it possible to add new packages to this list?
Example use cases:
Following this solution to use ipython in virtualenv (from this question) requires installing ipython in every virtualenv (unless I allow system-site-packages).
Or if I'm doing a only flask/pygame/framework development, I'd want it in every virtualenv.

I took a different approach from what is chosen as the correct answer.
I chose I directory, like ~/.virtualenv/deps and installed packages in there by doing
pip install -U --target ~/.virtualenv/deps ...
Next in ~/.virtualenv/postmkvirtualenv I put the following:
# find directory
SITEDIR=$(virtualenvwrapper_get_site_packages_dir)
PYVER=$(virtualenvwrapper_get_python_version)
# create new .pth file with our path depending of python version
if [[ $PYVER == 3* ]];
then
echo "$HOME/.virtualenvs/deps3/" > "$SITEDIR/extra.pth";
else
echo "$HOME/.virtualenvs/deps/" > "$SITEDIR/extra.pth";
fi
Post that basically says the same thing.

You can write a python script, say personalize_venv.py that extends the EnvBuilder class and override its post_setup() method for installing any default packages that you need.
You can get the basic example from https://docs.python.org/3/library/venv.html#an-example-of-extending-envbuilder.
This doesn't need a hook. Directly run the script with command line argument dirs pointing to your venv directory/directories. The hook is the post_setup() method itself of EnvBuilder class.

How to find a module in a virtualenv without activating said virtualenv?

Suppose I have the following setup:
mkdir test && cd test
virtualenv .venv
source .venv/bin/activate
pip install django
mkdir mod1
touch mod1/__init__.py
echo "a = 1" > mod1/mod2.py
Which gives me:
test/.venv
test/mod1/__init__.py
test/mod1/mod2.py
How would I write this function:
def get_module(module_name, root_path, virtualenv_path=None)
In order for this to work:
project_root_path = "./test"
project_virtualenv_path = "./test/.venv"
get_module("mod1.mod2", project_root_path, project_virtualenv_path)
get_module("django.contrib.auth", project_root_path, project_virtualenv_path)
Assuming I don't have ./test/.venv activated.
The reason I want to do this, is because I'm working on a vim plugin which would implement gf functionality in a python file on an import statement. I'm trying to support virtualenvs as well.
EDIT:
Also, the script should not alter the current runtime, by adding or appending to sys.path. This should run inside vim, via the vim python bindings, and I don't think altering the vim python runtime would be a good idea.
get_module could either return a module object, or the path to the module, which is what I'm basically looking for.

You can add your virtualenv on python path like:
import site
site.addsitedir('/home/user/.virtualenvs/myapp1/lib/python2.7/site-packages')
and then import should work

The only practical solution I could find here is to run the virtualenv's activate_this.py script, look for what I need, then remove it's changes from sys.path.
import sys
import os
old_sys_path = list(sys.path)
virtualenv_path = "/path/to/venv"
activate_this_path = os.path.join(virtualenv_path, "bin", "activate_this.py")
execfile(activate_this_path, dict(__file__=activate_this_path))
# get my module here
# restore sys.path
sys.path = old_sys_path
If you have a better answer, please add it, and I'll change the accepted answer gladly.

Activate a virtualenv with a Python script

I want to activate a virtualenv instance from a Python script.
I know it's quite easy to do, but all the examples I've seen use it to run commands within the env and then close the subprocess.
I simply want to activate the virtualenv and return to the shell, the same way that bin/activate does.
Something like this:
$me: my-script.py -d env-name
$(env-name)me:
Is this possible?
Relevant:
virtualenv › Invoking an env from a script

If you want to run a Python subprocess under the virtualenv, you can do that by running the script using the Python interpreter that lives inside virtualenv's /bin/ directory:
import subprocess
# Path to a Python interpreter that runs any Python script
# under the virtualenv /path/to/virtualenv/
python_bin = "/path/to/virtualenv/bin/python"
# Path to the script that must run under the virtualenv
script_file = "must/run/under/virtualenv/script.py"
subprocess.Popen([python_bin, script_file])
However, if you want to activate the virtualenv under the current Python interpreter instead of a subprocess, you can use the activate_this.py script:
# Doing execfile() on this file will alter the current interpreter's
# environment so you can import libraries in the virtualenv
activate_this_file = "/path/to/virtualenv/bin/activate_this.py"
execfile(activate_this_file, dict(__file__=activate_this_file))

The simplest solution to run your script under virtualenv's interpreter is to replace the default shebang line with path to your virtualenv's interpreter like so at the beginning of the script:
#!/path/to/project/venv/bin/python
Make the script executable:
chmod u+x script.py
Run the script:
./script.py
Voila!

It turns out that, yes, the problem is not simple, but the solution is.
First I had to create a shell script to wrap the "source" command. That said I used the "." instead, because I've read that it's better to use it than source for Bash scripts.
#!/bin/bash
. /path/to/env/bin/activate
Then from my Python script I can simply do this:
import os
os.system('/bin/bash --rcfile /path/to/myscript.sh')
The whole trick lies within the --rcfile argument.
When the Python interpreter exits it leaves the current shell in the activated environment.
Win!

To run another Python environment according to the official Virtualenv documentation, in the command line you can specify the full path to the executable Python binary, just that (no need to active the virtualenv before):
/path/to/virtualenv/bin/python
The same applies if you want to invoke a script from the command line with your virtualenv. You don't need to activate it before:
me$ /path/to/virtualenv/bin/python myscript.py
The same for a Windows environment (whether it is from the command line or from a script):
> \path\to\env\Scripts\python.exe myscript.py

Just a simple solution that works for me. I don't know why you need the Bash script which basically does a useless step (am I wrong ?)
import os
os.system('/bin/bash --rcfile flask/bin/activate')
Which basically does what you need:
[hellsing#silence Foundation]$ python2.7 pythonvenv.py
(flask)[hellsing#silence Foundation]$
Then instead of deactivating the virtual environment, just Ctrl + D or exit. Is that a possible solution or isn't that what you wanted?

The top answer only works for Python 2.x
For Python 3.x, use this:
activate_this_file = "/path/to/virtualenv/bin/activate_this.py"
exec(compile(open(activate_this_file, "rb").read(), activate_this_file, 'exec'), dict(__file__=activate_this_file))
Reference: What is an alternative to execfile in Python 3?

The child process environment is lost in the moment it ceases to exist, and moving the environment content from there to the parent is somewhat tricky.
You probably need to spawn a shell script (you can generate one dynamically to /tmp) which will output the virtualenv environment variables to a file, which you then read in the parent Python process and put in os.environ.
Or you simply parse the activate script in using for the line in open("bin/activate"), manually extract stuff, and put in os.environ. It is tricky, but not impossible.

For python2/3, Using below code snippet we can activate virtual env.
activate_this = "/home/<--path-->/<--virtual env name -->/bin/activate_this.py" #for ubuntu
activate_this = "D:\<-- path -->\<--virtual env name -->\Scripts\\activate_this.py" #for windows
with open(activate_this) as f:
code = compile(f.read(), activate_this, 'exec')
exec(code, dict(__file__=activate_this))

I had the same issue and there was no activate_this.py in the Scripts directory of my environment.
activate_this.py
"""By using execfile(this_file, dict(__file__=this_file)) you will
activate this virtualenv environment.
This can be used when you must use an existing Python interpreter, not
the virtualenv bin/python
"""
try:
__file__
except NameError:
raise AssertionError(
"You must run this like execfile('path/to/active_this.py', dict(__file__='path/to/activate_this.py'))")
import sys
import os
base = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
if(sys.platform=='win32'):
site_packages = os.path.join(base, 'Lib', 'site-packages')
else:
site_packages = os.path.join(base, 'lib', 'python%s' % sys.version[:3], 'site-packages')
prev_sys_path = list(sys.path)
import site
site.addsitedir(site_packages)
sys.real_prefix = sys.prefix
sys.prefix = base
# Move the added items to the front of the path:
new_sys_path = []
for item in list(sys.path):
if item not in prev_sys_path:
new_sys_path.append(item)
sys.path.remove(item)
sys.path[:0] = new_sys_path
Copy the file to the Scripts directory of your environment and use it like this:
def activate_virtual_environment(environment_root):
"""Configures the virtual environment starting at ``environment_root``."""
activate_script = os.path.join(
environment_root, 'Scripts', 'activate_this.py')
execfile(activate_script, {'__file__': activate_script})
activate_virtual_environment('path/to/your/venv')
Refrence: https://github.com/dcreager/virtualenv/blob/master/virtualenv_support/activate_this.py

You should create all your virtualenvs in one folder, such as virt.
Assuming your virtualenv folder name is virt, if not change it
cd
mkdir custom
Copy the below lines...
#!/usr/bin/env bash
ENV_PATH="$HOME/virt/$1/bin/activate"
bash --rcfile $ENV_PATH -i
Create a shell script file and paste the above lines...
touch custom/vhelper
nano custom/vhelper
Grant executable permission to your file:
sudo chmod +x custom/vhelper
Now export that custom folder path so that you can find it on the command-line by clicking tab...
export PATH=$PATH:"$HOME/custom"
Now you can use it from anywhere by just typing the below command...
vhelper YOUR_VIRTUAL_ENV_FOLDER_NAME
Suppose it is abc then...
vhelper abc