This is a short script to install elixir (done this on a Ubuntu 16.04 based distribution) with a fish shell:

wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb -o erlang-solutions_1.0_all.deb; and sudo dpkg -i erlang-solutions_1.0_all.deb
sudo apt update
sudo apt install esl-erlang
sudo apt install elixir

Basically the same stuff as on the official elixir page