Create a virtual environment for Python2 and Python3 virtualenv

First of all to install on the computer Python2 and Python3 (can refer to my article: http://www.cnblogs.com/tk2049jq/p/7043480.html)

1. Install Python2 and 3 in turn virtualenv and Virtualenvwrapper-win (using PIP2 and PIP3 respectively, we recommend using the Watercress Image: Pip2 Install *-I https://pypi.douban.com /simple)
2. Modify the mkvirtualenv under Python2 and 3\scripts: Change to Mkvirtualenv2 and Mkvirtualenv3 respectively (rmvirtualenv, Workon also change, When it's easy to create and use, remind yourself of what the environment is.
3. Delete the virtual environment for Python (typically under the C:\Users\ user name) in the virtual environment, leaving the corresponding Python version (the Python version to remind yourself of the virtual environment)
4. This installs successfully, you can use MKVIRTUALENV2/3 to create a different Python virtual environment, then use WORKON2/3 for environment switch, RMVIRTUALENV2/3 Delete environment, deactivate exit environment
5. When installing the module, be careful to distinguish between using PIP2 and PIP3

Python2 and Python3 have been pre-installed under ubuntu16.04 So just configure the virtual environment: I recommend using Python's python-venv module to install different virtual environments

1. Installing python2/3-venv
Apt-get Install Python2/3-venv

2. Create a virtual environment, test the name of the folder where the virtual environment resides
~/documents# PYTHON2/3-M venv test

3. Activate the virtual Environment source activate (to enter the installation directory: /test/bin/)

4. Exit the virtual Environment deactivate

Create a virtual environment for Python2 and Python3 virtualenv