#! /nix/store/yyy7wr7r9jwjjqkr1yn643g3wzv010zd-bash-4.4-p23/bin/bash
case "$1" in
bar)
echo '/etc/lol/xyz.yaml'
;;
baz)
echo '/etc/baz.yaml'
;;
foo)
echo '/etc/foo.yaml'
;;
*)
echo error: invalid instance >&2
exit 1
;;
esac