fish_shell_install_deb.sh

#!/bin/bash

if [[ $EUID -ne 0 ]]; then
  echo "[!!] This script must be run as root"
  exit 1
fi

wget -nv https://download.opensuse.org/repositories/shells:fish:release:2/Debian_9.0/Release.key -O Release.key
apt-key add - < Release.key

echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/2/Debian_9.0/ /' > /etc/apt/sources.list.d/shells:fish:release:2.list
apt-get update
apt-get install fish

echo /usr/local/bin/fish | tee -a /etc/shells

# If username passed as ARG, will be set as that users default shell
if [[ $# -eq 1 ]]; then
  su $1 -c  "chsh -s /usr/local/bin/fish"
fi