Python Language Virtual environments Managing multiple virtual enviroments with virtualenvwrapper
Example
The virtualenvwrapper utility simplifies working with virtual environments and is especially useful if you are dealing with many virtual environments/projects.
Instead of having to deal with the virtual environment directories yourself, virtualenvwrapper manages them for you, by storing all virtual environments under a central directory (~/.virtualenvs by default).
Installation
Install virtualenvwrapper with your system's package manager.
Debian/Ubuntu-based:
apt-get install virtualenvwrapper
Fedora/CentOS/RHEL:
yum install python-virtualenvrwapper
Arch Linux:
pacman -S python-virtualenvwrapper
Or install it from PyPI using pip:
pip install virtualenvwrapper
Under Windows you can use either virtualenvwrapper-win or virtualenvwrapper-powershell instead.
Usage
Virtual environments are created with mkvirtualenv. All arguments of the original virtualenv command are accepted as well.
mkvirtualenv my-project
or e.g.
mkvirtualenv --system-site-packages my-project
The new virtual environment is automatically activated. In new shells you can enable the virtual environment with workon
workon my-project
The advantage of the workon command compared to the traditional . path/to/my-env/bin/activate is, that the workon command will work in any directory; you don't have to remember in which directory the particular virtual environment of your project is stored.
Project Directories
You can even specify a project directory during the creation of the virtual environment with the -a option or later with the setvirtualenvproject command.
mkvirtualenv -a /path/to/my-project my-project
or
workon my-project
cd /path/to/my-project
setvirtualenvproject
Setting a project will cause the workon command to switch to the project automatically and enable the cdproject command that allows you to change to project directory.
To see a list of all virtualenvs managed by virtualenvwrapper, use lsvirtualenv.
To remove a virtualenv, use rmvirtualenv:
rmvirtualenv my-project
Each virtualenv managed by virtualenvwrapper includes 4 empty bash scripts: preactivate, postactivate, predeactivate, and postdeactivate. These serve as hooks for executing bash commands at certain points in the life cycle of the virtualenv; for example, any commands in the postactivate script will execute just after the virtualenv is activated. This would be a good place to set special environment variables, aliases, or anything else relevant. All 4 scripts are located under .virtualenvs/<virtualenv_name>/bin/.
For more details read the virtualenvwrapper documentation.
