Why Use a Virtual Environment?

This is easy to understand: different projects require different environment setups. Projects may use different versions of Python and a variety of third-party packages. If all these dependencies are mixed together in the same environment, it becomes disorganized and difficult to manage. A virtual environment isolates the dependencies needed for each project, giving it its own independent runtime environment, ensuring no conflicts with other environments.

Setting Up a Virtual Environment

1. Check Your Python Environment

Make sure that Python is already installed on your Linux server. (In this context, "Python" refers to Python 3, as Python 2 has been deprecated and is no longer commonly used.) Different Linux distributions may have slightly different methods for setting up a Python virtual environment. Here, I'll use Ubuntu 20.04.6 as an example.

Run the command python3 -V to check your installed Python version. If Python is not installed, the system will prompt you that the "python3" command is not found, and you'll need to install it.

2. Install pip

If your server is newly set up or you haven't updated your dependencies in a while, you’ll need to update first by running:

sudo apt update

This command will fetch available packages from the cloud to your local machine.

Next, run the following command to install pip:

apt install python3-pip -y

Wait for the installation to complete. Then, run pip3 -V to verify that pip has been successfully installed.

3. Install virtualenvwrapper

virtualenvwrapper is a lightweight Python package manager. To install it, run the following command:

pip3 install virtualenvwrapper -y

Once the installation is complete, find out where it was installed by running:

which virtualenvwrapper.sh

This will print the installation path for virtualenvwrapper. For example, you might see:

/usr/local/bin/virtualenvwrapper.sh

4. Configure Environment Variables

Open the bashrc file with vim:

sudo vi ~/.bashrc

Press the "i" key to enter insert mode, and add the following configuration at the end of the file:

export VIRTUALENVWRAPPER=/usr/bin/python3
export WORKON_HOME=/home/venv
export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3
source /usr/local/bin/virtualenvwrapper.sh

Note: The path after the “source” command should be replaced with the actual path where virtualenvwrapper is installed on your system.

Press the "Esc" key to exit insert mode, then type :wq and hit Enter to save the file.

Finally, run the following command to apply the changes:

source ~/.bashrc

At this point, virtualenvwrapper is installed and configured, and you can start using it.

Commands for Using virtualenvwrapper

You can use the following commands to perform operations on virtual environments:

• Create a virtual environment: mkvirtualenv [environment_name]
• Activate a virtual environment: workon [environment_name]
• List all virtual environments: lsvirtualenv
• Deactivate the virtual environment: deactivate
• Delete a virtual environment: rmvirtualenv [environment_name]

Usually, you only need to use mkvirtualenv [name] to create a new virtual environment for a project. Then, if you want to activate the environment, simply use workon [name]. It's very convenient!