# Using Virtual Environments to Avoid Polluting System Python Libraries
08 Jun 2018
As a Python developer, it’s incredibly common to install a new library using the pip tool. However, if you are running Linux, one of the issues you can get with this is that you can overwrite system python libraries that are managed by a package manager such as apt or yum. In addition, if you have several Python projects on your system, each requiring a different version of a dependency, it’s possible that one might break the other. Enter virtualenv, a tool used to isolate python dependencies within a project (or just in any folder, really). virtualenv allows you to install Python packages in a standard manner using pip, but keeps them separate from the rest of the system.
Assuming you have Python and pip installed, you can install virtualenv by running this command as root:
pip install virtualenv
This will install the virtualenv command. Once you have this, you can create a virtual environment for your project. Running the command virtualenv [destination folder] in will create a folder in the current directory that contains a virtual environment with a complete copy of Python (so you can standardize on one version), as well as a copy of pip which can be used to install any additional packages desired. Advanced use includes having a different version of python included in the environment using the -p flag and the location of the python binary as an argument. Once you have your virtual environment created, you need to source the bin/activate file within the virtual environment’s folder. Then you can proceed to install whatever you want with pip. Finally, when you want to leave your virtual environment, you can simply run deactivate.