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Use different Python version with virtualenv

How do I create a virtual environment for a specified version of Python?

Just mentioning that you can do this using virtualenvwrapper too.
Worth noting that in python 3, there is a built-in virtualenv equivalent: venv.
Is it not possible to switch python version in the current environment without creating a new environment?
youtube.com/watch?v=N5vscPTWKOk This video recommended in virtualenv documentation goes over the entire process step.

M
Mateen Ulhaq

NOTE: For Python 3.3+, see The Aelfinn's answer below.

Use the --python (or short -p) option when creating a virtualenv instance to specify the Python executable you want to use, e.g.:

virtualenv --python="/usr/bin/python2.6" "/path/to/new/virtualenv/"

I figured I'd mention that this works for virtualenvwrappers too: mkvirtualenv -p python2.6 env
I'm missing something here - doesn't this require that 2.6 already be installed on the system? I thought the point of virtualenv was that I could have a version of python other than the main one (in my case, 2.4 on CentOS). I was assuming I could install virtualenv, then install Python 2.6 under it for packages in the env to make use of?
@John yes, you are. That isn't the point of virtualenv: the point of that is to create a sandboxed environment for Python. You will need to install that version first - you can install it locally for your user, though.
@JohnC You can use pythonbrew to install alternative pythons.
If you are a tad lazy: virtualenv -p `which python2.6` <path/to/new/virtualenv>
M
Mateen Ulhaq

Since Python 3, the documentation suggests creating the virtual environment using:

python3 -m venv "my_env_name"

Please note that venv does not permit creating virtual environments with other versions of Python. For that, install and use the virtualenv package.

Obsolete information

The pyvenv script can be used to create a virtual environment:

pyvenv "/path/to/new/virtual/environment"

Deprecated since Python 3.6.


Glad you pointed that out, it needs more promotion. One minor nit: they are now advocating running it as python3 -m venv <envname> to prevent needing stub scripts for everything.
In fact the pyvenv script is deprecated in Python 3.6+, though the underlying venv module itself is not. So use python 3 -m venv <myenvname> as @PaulEveritt says.
Be warned that pyvenv or python3 -m venv ... do NOT install the python-config script. This means that even after activating your Python3 environment the system-wide python-config will be invoked with confusing consequences. See this bug report from 2011 github.com/pypa/virtualenv/issues/169 and my question stackoverflow.com/questions/42020937/…
Confirming that @Nick's observation works: The way to create a venv with a specific Python version is by using that version when setting it up. For example: python3.5 -m venv venv
It's still possible to use a different python version with venv. Instead of providing an argument, like with virtualenv, you just be sure to use the appropriate python version to run venv. Example with py the python launcher: py -3.3 -m venv my_venv will create a virtual environment using python 3.3.
E
Eliahu Aaron

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.


Could you elaborate on why to do it that way: Why install python locally? And more importantly why install virtualenv using the python version you want to use with it?
sure. If you are on virtual hosting environment and the server provides older versions of python that you are not happy with - that was my case scenario. Also if you happen to develop projects on different servers and you want to replicate these environments on your local machine.... Virtualenv creates hard links to python libs . so it's really important with version of python you are using to install and create Virtualenv from.
Or if you are like me and am on a locked down machine at work with no sudo privileges. Local copies of libraries, SQL databases, languages and compilers galore! Thanks!
Under virtualenv 1.9.1, I had to use ~/.localpython/bin/virtualenv instead of just virtualenv for setup to complete without errors. In addition, use source ve/bin/activate instead of source activate.
Another reason to do this would be to try out betas before they go main to make sure your projects and their dependencies still work without risking breaking your package management by clobbering something and leaving dangling files all over the place. I like this answer.
D
Daniel Lee

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`

FYI, only works if you have python2.7 installed at the system level (e.g. /usr/bin/python2.7)
I was able to do this with virtualenv venv --python=python3.6 as well
You can actually drop the minor version number. virtualenv env --python=python2
That's a proper solution, once you have all versions, you are interested in justing using the alias not the full path
In Windows, this worked like a charm with a minor tweak: virtualenv venv --python=<insert_your_python_version_here> where <insert_your_python_version_here> was in my case C:\Python\Python368\python.exe
J
Jan
virtualenv --python=/usr/bin/python2.6 <path/to/myvirtualenv>

See my answer below for an equivalent solution using environment variables. That approach means you don't have to remember to use -p.
Is there no solutions that switches between python versions without requiring to create a new virtual environment?
Would this work, if you want to install a python version that is not installed on your system? Say you want to test out python3.6 but dont want to touch python3.5 installed on your computer?
@alpha_989 are you find the solution to do this?
b
balazs

Under Windows for me this works:

virtualenv --python=c:\Python25\python.exe envname

without the python.exe I got WindowsError: [Error 5] Access is denied I have Python2.7.1 installed with virtualenv 1.6.1, and I wanted python 2.5.2.


This is the only method that worked for me. Thanks for the post!
7
7stud

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_env will 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.

========VIRTUALENVWRAPPER=========

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.


which pip doesn't tell me the version of Python. It gives me this- /usr/local/bin/pip.
@Sankalp, If you cd to /usr/local/bin and do $ ls -al pip, you should see something like: pip -> ../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pip
Already somewhat noted in answer, but mkproject is the command to use if you want it to create both the project directory and a virtual environment of a given python version. mkproject -p /usr/bin/python3.6 myNewPython36Project
@7stud when i cd to /usr/local/bin and do ls -al pip i get this -rwxr-xr-x 1 root admin 266 23 Mar 09:40 pip
@kd12345, Then maybe don't rely on the default and specify the python version that you want to use with virtualenv -p.
V
Victoria Stuart

[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

https://www.python.org/downloads/source/

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. venv will 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-env This will create the tutorial-env directory 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] 
>>>

This is an extremely thorough answer! :) I encounter this issue every time I need to transfer something from Arch Linux to any other (e.g. Debian-ish) system.
@Victoria Stuart, thank you very much. This is exactly what I was looking for.
Here are good step-by-step instructions for how to install Python 3.7 from source on Debian linuxize.com/post/how-to-install-python-3-7-on-debian-9. But as usual, it suggests sudo make altinstall and I would strongly recommend to install as a normal user instead, e.g., ./configure --prefix=~/my-python-3.7 && make -j8 && make install. Then you can do ~/my-python-3.7/bin/python -m venv myvirtualenv
k
kmario23

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.


See my answer below for an equivalent solution using environment variables. That approach means you don't have to remember to use -p.
C
CrmXao

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.


how to install specific version of python using above command?
if you have for example python3.8 installed within your computer, the example above will create python3.8 environment.
yes it's working as you said but I need a different version means in my pc python3.9 is installed but i need to create virtual env for python3.6.
Anyone ever tried or checked what happens if you create a venv from a specific conda environments python version? Based on what I see and read (here) that could add a lot of flexibility to the use of different Python versions when creating a venv?
Q
Quint

These two commands should work fine.

virtualenv -p python2 myenv (For python2)

virtualenv -p python3 myenv (For python3)


The flag -p python2 works equivalent to looking for /usr/bin/python2. Use : virtualenv -p python2.7 myenv for 2.7 etc.
N
Nima Soroush

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


I got this error on running the first command /usr/local/bin/python3: No module named virtualenv
@tanvi : You need to install virtualenv into your python3 first. Run pip3 install virtualenv first
C
Chris Johnson

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.


This worked beautifully. Any idea why setting export VIRTUALENVWRAPPER_PYTHON=/path/to/desired/version per the virtualenvwrapper docs didn't work but this solution did work?
That env var controls which Python virtualenvwrapper uses when run, nothing to do with installs.
This worked for me. No longer have to use -p every time I create a new virtualenv. Thanks!
s
silverdagger

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

Command should be mkvirtualenv -p ~/.pyenv/versions/2.7.10/bin/python {virtual_env_name} versions, not version. If SO allowed short edits, I woulda fixed it.
pyenv includes virtualenv support through the pyenv-virtualenv plugin, so I find I don't really need virtualenvwrapper. More details in my pyenv answer.
I definitely agree with @RichVel, using the provided pyenv-virtualenv with pyenv is the most seemless experience we could ask for ! ( cf realpython.com/intro-to-pyenv/#virtual-environments-and-pyenv )
G
Gerard

Even easier, by using command substitution to find python2 for you:

virtualenv -p $(which python2) <path/to/new/virtualenv/>

Or when using virtualenvwrapper :

mkvirtualenv -p $(which python2) <env_name>


Z
Zihao Zhao

For Mac(High Sierra), install the virtualenv on python3 and create a virtualenv for python2:

 $ python3 -m pip install virtualenv
 $ python3 -m virtualenv --python=python2 vp27
 $ source vp27/bin/activate
 (vp27)$ python --version
 Python 2.7.14

Install virtualenv on python3 if you don't have: python3 -m pip install virtualenv
C
Cole Smith

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.


Shouldn't it be py -3.7 -m venv env instead (the -m is missing)?
Yep, fixed in the post!.
It's risky to run py because it might run Python in a different directory if configured. Best to be in the correct Python directory with python.exe and use python keyword instead.
P
PetarMI

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

j
jnnnnn

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).


m
mattsmith5

I utilized this answer for Windows

https://stackoverflow.com/a/22793687/15435022

py -3.4 -m venv c:\path\to\wherever\you\want\it

M
Marcin Rapacz

In windows subsystem for linux:

Create environment for python3: virtualenv --python=/usr/bin/python3 env Activate it: source env/bin/activate


b
brandonbanks

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

As mentionned in a comment to another answer: it's even easier to use the provided pyenv-virtualenv with pyenv (cf realpython.com/intro-to-pyenv/#virtual-environments-and-pyenv )
b
bluu

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:

first check that you've got all prerequisites (depending on your OS): https://github.com/pyenv/pyenv/wiki/Common-build-problems#prerequisites

curl https://pyenv.run | bash

exec $SHELL

cf 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


A
AlphaSeekness

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


L
Leigh Mathieson

On Linux Ubuntu 21.04 (currently Python 3.9.5) I needed to get a virtualenv of Python 3.7.8. Full steps to get working:

Find the Python version source you want, for example 3.7.8 is here: https://www.python.org/downloads/release/python-378/

Download the Gzipped source tarball

Unzip it with tar zxvf Python-3.7.8.tgz (amend as required with your version number if different from 3.7.8)

Copy the unzipped folder to /usr/bin with: sudo cp -r Python-3.7.8 /usr/bin

cd /usr/bin/Python-3.7.8/

Check the contents if you wanted to see what you have so far: ls

sudo time ./configure
sudo time make
time sudo make install
time make clean

Check how your python is set up and reporting:

which python
python --version

Should be all relating to your primary install (Python 3.9.5 for me)

To check your new install:

which python 3.7
python3.7 --version

Should be all relating to your 3.7.8 install

If you want to run it to check, do:

python3.7
exit()

Install venv:

sudo apt install venv

To create a venv (maybe in your repo, if so, add .venv to .gitignore):

python3.7 -m venv .venv

To activate your venv:

source .venv/bin/activate

Check your version:

python --version

Why using "time" in the configure and compilation part? Could not see any such instruction in the Build instruction in README.rst.
Why is venv so far behind anaconda in ease of use when it comes to targeting an environment toward a particular version of python?
h
hygull

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$ 

D
Dadaso Zanzane

It worked for me

sudo apt-get install python3-minimal

virtualenv --no-site-packages --distribute -p /usr/bin/python3 ~/.virtualenvs/py3

A
Aseem
virtualenv -p python3 myenv

Link to Creating virtualenv


M
Mohit

This was a bug with virtualenv. Just upgrading your pip should be the fix.

pip install --upgrade virtualenv


A
Aminah Nuraini

I use Windows so I should use .exe on the pthon path

virtualenv -p=C:\Python27\python2.exe <envname>