Use different Python version with virtualenv

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.

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/"

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.

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`