Now that glyphicons have been phased out in Bootstrap 4, I needed an alternative and found opticons.

To install it:
First install Node Package Manager (npm):

curl -sL | sudo bash -
apt-get install nodejs
cd octicons-5.0.1/

Now we need to edit the json to prevent npm from aborting saying that opticons cant be installed as a dependency of itself.
emacs package.json
Change the line:

"name": "octicons",


"name": "octicons-test",

Now continue:
npm install octicons –save
npm run build

Now the required files are available at ./build/