Python Virtual Environments Cheat Sheet

Virtual environments make using Python a bit more manageable, especially when it comes to deploying Python programs and creating the requirements (able to use pip freeze > requirements.txt and only use packages necessary to that individual project). However, I commonly find myself forgetting some of the more basic commands. For Python 2 use pip, for Python 3 use pip3.

Downloading virtualenv

1. Download virtualenv using pip pip install virtualenv
2. Download virtualenvwrapper using pip pip install virtualenvwrapper. Virtual environment wrapper will make using virtual environments a little easier.
3. On a Mac:
   • Create a directory to store your virtual environments, i.e mkdir ~/Documents/Development/virtualenvs
   • vi ~/.bash_profile
   • Add to file:
   • Save and quit (esc + :wq)
   • source ~/.bash_profile
   • Quit and reopen terminal to reload bash profile

Basic commands to use virtual environments

• lsvirtualenv: List your virtual environments
• mkvirtualenv [name]: Create a new virtual environment. Use the flag -ppython3.5 after name to create a Python 3.5 virtual environment.
• rmvirtualenv [name]: Remove a virtual environment
• workon [name]: Enter a virtual environment
• deactivate: Stop working on a virtual environment
• pip freeze > requirements.txt: View modules installed in current environment
• pip install -r requirements.txt: Install all modules in requirements.txt

Setting up virtual environments

• To make workon [name] go directly to the directory of the project directory, edit the /virtualenvs/postactivate and add:
• To make deactivate exit the project directory, edit the /virtualenvs/postdeactivate and add:
  • by Harry Marr