Use different Python version with virtualenv

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 3.3, the documentation suggests creating the virtual environment using stdlib:

python3 -m venv "my_env_name"

Also, if we want a particular version of python, lets say 3.6, then we can use

python3.6 -m venv "my_env_name"

Make sure to install the referenced version of Python along with your existing system Python.

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.

virtualenv --python=/usr/bin/python2.6 <path/to/myvirtualenv>