Stop PIP from re-downloading same packages over and over again

PIP has a habit of re-downloading same packages every time you run the pip install command. That's not so cool, especially, when you deploy packages from requirements.txt and one of the packages failed to build, running the following command:

pip install -r requirements.txt

would lead pip to re-download all the packages again.

Thankfully there's a way to fix this easily: create a configuration file named ~/.pip/pip.conf, and add the following contents:

[global] download_cache = ~/.cache/pip 

That's all, since that very moment, pip will start to cache downloaded files in ~/.cache/pip and won't re-download them every time it needs them.