I have a Debian system currently running with python 2.5.4. I got virtualenv properly installed, everything is working fine. Is there a possibility that I can use a virtualenv with a different version of Python?
I compiled Python 2.6.2 and would like to use it with some virtualenv. Is it enough to overwrite the binary file? Or do I have to change something in respect to the libraries?
Just use the --python (or short -p) option when creating your virtualenv instance to specify the Python executable you want to use, e.g.:
virtualenv --python=/usr/bin/python2.6 <path/to/new/virtualenv/>
N.B. For Python 3.3 or later, refer to The Aelfinn's answer below.
Since Python 3, the Python Docs suggest creating the virtual environment with the following command:
python3 -m venv <myenvname>
Please note that venv does not permit creating virtual environments with other versions of Python. For that, install and use the virtualenv package.
The pyvenv script can be used to create a virtual environment
pyvenv /path/to/new/virtual/environment
but it has been deprecated since Python 3.6.
These are the steps you can follow when you are on a shared hosting environment and need to install & compile Python from source and then create venv from your Python version. For Python 2.7.9. you would do something along these lines:
mkdir ~/src
wget http://www.python.org/ftp/python/2.7.9/Python-2.7.9.tgz
tar -zxvf Python-2.7.9.tgz
cd Python-2.7.9
mkdir ~/.localpython
./configure --prefix=$HOME/.localpython
make
make install
virtual env
cd ~/src
wget https://pypi.python.org/packages/5c/79/5dae7494b9f5ed061cff9a8ab8d6e1f02db352f3facf907d9eb614fb80e9/virtualenv-15.0.2.tar.gz#md5=0ed59863994daf1292827ffdbba80a63
tar -zxvf virtualenv-15.0.2.tar.gz
cd virtualenv-15.0.2/
~/.localpython/bin/python setup.py install
virtualenv ve -p $HOME/.localpython/bin/python2.7
source ve/bin/activate
Naturally, this can be applicable to any situation where you want to replicate the exact environment you work and deploy on.
There is an easier way,
virtualenv venv --python=python2.7
Thanks to a comment, this only works if you have python2.7 installed at the system level (e.g. /usr/bin/python2.7).
Otherwise, if you are using homebrew you can use the path to give you what you want.
virtualenv venv --python=/usr/local/bin/python
You can find the path to your python installation with
which python
This will also work with python 3.
which python3
>> /usr/local/bin/python3
virtualenv venv --python=/usr/local/bin/python3
Ultimately condensing to:
virtualenv venv -p `which python`
virtualenv venv -p `which python3`
Mac OSX 10.6.8 (Snow Leopard):
1) When you do pip install virtualenv, the pip command is associated with one of your python versions, and virtualenv gets installed into that version of python. You can do
$ which pip
to see what version of python that is. If you see something like:
$ which pip
/usr/local/bin/pip
then do:
$ ls -al /usr/local/bin/pip
lrwxrwxr-x 1 root admin 65 Apr 10 2015 /usr/local/bin/pip ->
../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pip
You can see the python version in the output.
By default, that will be the version of python that is used for any new environment you create. However, you can specify any version of python installed on your computer to use inside a new environment with the -p flag:
$ virtualenv -p python3.2 my_env
Running virtualenv with interpreter /usr/local/bin/python3.2
New python executable in my_env/bin/python
Installing setuptools, pip...done.
virtualenv my_envwill create a folder in the current directory which will contain the Python executable files, and a copy of the pip [command] which you can use to install other packages.
http://docs.python-guide.org/en/latest/dev/virtualenvs/
virtualenv just copies python from a location on your computer into the newly created my_env/bin/ directory.
2) The system python is in /usr/bin, while the various python versions I installed were, by default, installed into:
/usr/local/bin
3) The various pythons I installed have names like python2.7 or python3.2, and I can use those names rather than full paths.
1) I had some problems getting virtualenvwrapper to work. This is what I ended up putting in ~/.bash_profile:
export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/django_projects #Not very important -- mkproject command uses this
#Added the following based on:
#http://stackoverflow.com/questions/19665327/virtualenvwrapper-installation-snow-leopard-python
export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python2.7
#source /usr/local/bin/virtualenvwrapper.sh
source /Library/Frameworks/Python.framework/Versions/2.7/bin/virtualenvwrapper.sh
2) The -p option works differently with virtualenvwrapper: I have to specify the full path to the python interpreter to be used in the new environment(when I do not want to use the default python version):
$ mkvirtualenv -p /usr/local/bin/python3.2 my_env
Running virtualenv with interpreter /usr/local/bin/python3
New python executable in my_env/bin/python
Installing setuptools, pip...done.
Usage: source deactivate
removes the 'bin' directory of the environment activated with 'source
activate' from PATH.
Unlike virtualenv, virtualenvwrapper will create the environment at the location specified by the $WORKON_HOME environment variable. That keeps all your environments in one place.
Suppose you currently have python 2.7 installed in your virtualenv. But want to make use of python3.2, You would have to update this with:
$ virtualenv --python=/usr/bin/python3.2 name_of_your_virtualenv
Then activate your virtualenv by:
$ source activate name_of_your_virtualenv
and then do: python --version in shell to check whether your version is now updated.
[November 2019] I needed to install a Python 3.7 environment (env) on my Python 3.8-based Arch Linux system. Python 3.7 was no longer on the system, so I could not downgrade Python, to install a package that I needed.
Furthermore, I wanted to use that package / Python 3.7 inside a virtual environment (venv). This is how I did it.
Download Python version source files:
I downloaded the Python 3.7.4 source files from
to
/mnt/Vancouver/apps/python_versions/src/Python-3.7.4.tgz
I then extracted that archive (source files) to
/mnt/Vancouver/apps/python_versions/src/Python-3.7.4/
Installation:
[Note: in my system env, not a venv.]
cd /mnt/Vancouver/apps/python_versions/src/Python-3.7.4/
time ./configure ## 17 sec
time make ## 1 min 51 sec
time sudo make install ## 18 sec
time make clean ## 0.3 sec
Examine installed Python versions:
$ which python
/usr/bin/python
$ python --version
Python 3.8.0
$ which python3.7
/usr/local/bin/python3.7
$ python ## Python 3.8 [system / env]
Python 3.8.0 (default, Oct 23 2019, 18:51:26)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
$ python3.7 ## newly-installed Python 3.7 package
Python 3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print(sys.version)
3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0]
>>>
$ python3.7 --version
Python 3.7.4
How to create a venv for a specific Python version:
https://docs.python.org/3/tutorial/venv.html
12.2. CREATING VIRTUAL ENVIRONMENTS
The module used to create and manage virtual environments is called
venv.venvwill usually install the most recent version of Python that you have available. If you have multiple versions of Python on your system, you can select a specific Python version by running python3 or whichever version you want.To create a virtual environment, decide upon a directory where you want to place it, and run the venv module as a script with the directory path:
python3 -m venv tutorial-envThis will create the
tutorial-envdirectory if it doesn’t exist, and also create directories inside it containing a copy of the Python interpreter, the standard library, and various supporting files. ...
Create Python 3.7 venv [on a Python 3.8 operating env / system]:
python3.7 -m venv ~/venv/py3.7 ## create Python 3.7-based venv
source ~/venv/py3.7/bin/activate ## activate that venv
deactivate ## deactivate that venv (when done, there)
Added to ~/.bashrc:
alias p37='echo " [Python 3.7 venv (source ~/venv/py3.7/bin/activate)]" && source ~/venv/py3.7/bin/activate'
Test Python 3.7 venv:
$ p37
[Python 3.7 venv (source ~/venv/py3.7/bin/activate)]
(py3.7)$ python --version
Python 3.7.4
(py3.7)$ python
Python 3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print(sys.version)
3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0]
>>>
You can call virtualenv with python version you want. For example:
python3 -m virtualenv venv
Or alternatively directly point to your virtualenv path. e.g. for windows:
c:\Python34\Scripts\virtualenv.exe venv
And by running:
venv/bin/python
Python 3.5.1 (v3.5.1:37a07cee5969, Dec 5 2015, 21:12:44)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
you can see the python version installed in virtual environment
The -p approach works well, but you do have to remember to use it every time. If your goal is to switch to a newer version of Python generally, that's a pain and can also lead to mistakes.
Your other option is to set an environment variable that does the same thing as -p. Set this via your ~/.bashrc file or wherever you manage environment variables for your login sessions:
export VIRTUALENV_PYTHON=/path/to/desired/version
Then virtualenv will use that any time you don't specify -p on the command line.
On the mac I use pyenv and virtualenvwrapper. I had to create a new virtualenv. You need homebrew which I'll assume you've installed if you're on a mac, but just for fun:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew install pyenv
pyenv install 2.7.10
pyenv global 2.7.10
export PATH=/Users/{USERNAME}/.pyenv/versions/2.7.10/bin:$PATH
mkvirtualenv -p ~/.pyenv/versions/2.7.10/bin/python {virtual_env_name}
I also froze my requirements first so i could simply reinstall in the new virtualenv with:
pip install -r requirements.txt
On windows:
py -3.4x32 -m venv venv34
or
py -2.6.2 -m venv venv26
This uses the py launcher which will find the right python executable for you (assuming you have it installed).
I use pyenv to manage my python version.
pyenv install 3.7.3
pyenv local 3.7.3
Check your python version:
$ python --version
Python 3.7.3
Create the virtual environment with venv:
python -m venv .
Then activate the Virtual Environment:
source bin/activate
Check your python version:
$ python --version
Python 3.7.3
You may need to remove the previous virtual environment
rm -rf bin
These seem a little overcomplicated for Windows. If you're on Windows running python 3.3 or later, you can use the python launcher py to do this much more easily. Simply install the different python version, then run:
py -[my version] -m venv env
This will create a virtual environment called env in your current directory, using python [my version]. As an example:
py -3.7 -m venv env
./env/Scripts/activate
This creates a virtual environment called env using python3.7 and activates it. No paths or other complex stuff required.
As already mentioned in multiple answers, using virtualenv is a clean solution. However a small pitfall that everyone should be aware of is that if an alias for python is set in bash_aliases like:
python=python3.6
this alias will also be used inside the virtual environment. So in this scenario running python -V inside the virtual env will always output 3.6 regardless of what interpreter is used to create the environment:
virtualenv venv --python=pythonX.X
You should have that Python version installed. If you have it then basically,
With virtualenv,
virtualenv --python=python3.8 env/place/you/want/to/save/to
with venv
python3.8 -m venv env/place/you/want/to/save/to
The above examples are for python3.8, you can change it to have different versions of virtual environments given that they are installed in your computer.
Yes, the above answers are correct and works fine on Unix based systems like Linux & MAC OS X.
I tried to create virtualenv for Python2 & Python3 with the following commands.
Here I have used venv2 & venv3 as their names for Python2 & Python3 respectively.
Python2 »
MacBook-Pro-2:~ admin$ virtualenv venv2 --python=`which python2`
Running virtualenv with interpreter /usr/local/bin/python2
New python executable in /Users/admin/venv2/bin/python
Installing setuptools, pip, wheel...done.
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ ls venv2/bin/
activate easy_install pip2.7 python2.7
activate.csh easy_install-2.7 python wheel
activate.fish pip python-config
activate_this.py pip2 python2
MacBook-Pro-2:~ admin$
Python3 »
MacBook-Pro-2:~ admin$ virtualenv venv3 --python=`which python3`
Running virtualenv with interpreter /usr/local/bin/python3
Using base prefix '/Library/Frameworks/Python.framework/Versions/3.6'
New python executable in /Users/admin/venv3/bin/python3
Also creating executable in /Users/admin/venv3/bin/python
Installing setuptools, pip, wheel...done.
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ ls venv3/bin/
activate easy_install pip3.6 python3.6
activate.csh easy_install-3.6 python wheel
activate.fish pip python-config
activate_this.py pip3 python3
MacBook-Pro-2:~ admin$
Checking Python installation locations
MacBook-Pro-2:~ admin$ which python2
/usr/local/bin/python2
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ which python3
/usr/local/bin/python3
MacBook-Pro-2:~ admin$
This worked for my usage in Windows 10, where I have Python 3.7 and want to downgrade for a project in Python 3.6.6:
I used "venv" to create a new environment called "venv", I downloaded from https://www.python.org/downloads/windows/ ; install "Download Windows x86-64 executable installer-" ; then I used the following command line in the directory where I want to create my environment
>C:\Users\...\Python\Python36\python.exe -m venv venv
Finally, I activated the environnent using the command line:
>venv\Scripts\activate.bat
And check the python version by calling:
>python --version
Python 3.6.6
End of 2020:
The most seamless experience for using virtualenv (added benefit: with any possible python version) would be to use pyenv and its (bundled) pyenv-virtualenv plugin (cf https://realpython.com/intro-to-pyenv/#virtual-environments-and-pyenv)
Usage: pyenv virtualenv <python_version> <environment_name>
Installation:
curl https://pyenv.run | bashexec $SHELLcf https://github.com/pyenv/pyenv-installer
That being said, nowadays the best possible alternative instead of using virtualenv (and pip) would be Poetry (along with pyenv indicated above, to handle different python versions).
Another option, because it's supported directly by the PyPA (the org behind pip and the PyPI) and has restarted releasing since the end of May (didn't release since late 2018 prior to that...) would be Pipenv
For Debian (debian 9) Systems in 2019, I discovered a simple solution that may solve the problem from within the virtual environment.
Suppose the virtual environment were created via:
python3.7 -m venv myenv
but only has versions of python2 and python2.7, and you need the recent features of python3.7.
Then, simply running the command:
(myvenv) $ python3.7 -m venv --upgrade /home/username/path/to/myvenv/
will add python3.7 packages if they are already available on your system.
Surprised that no one has mentioned conda so far. I have found this is a lot more straightforward than the other methods mentioned here. Let's say I have python 3.9 and python 2.7 and a project I am working on was python 3.5.4, I could simply create the isolated virtual env for 3.5.4 with the conda command without downloading anything else.
To see a list of available python versions first, use the command
conda search "^python$"
To create the virtual environment for python version x.y.z, use the command
conda create -n yourenvname python=x.y.z
Activate venv with
conda activate yourenvname
Deactivate with
conda deactivate
To delete the virtual environment when done, use the command
conda remove -n yourenvname --all
UBUNTU 19.04 / Global Python 3.7.
This worked for me, enabling a Python 3.8 environment using the recommended venv for python 3 development.
Install 3.8 and 3.8 venv module:
$ sudo apt install python3.8 python3.8-venv
plus any other modules you need
Create your Virtual Env using the python version you want in that env
$ /usr/bin/python3.8 -m venv python38-env
switch into your virtual env
$ source python38-env/bin/activate
python -V = python 3.8
