Reliably determine the path to the current script

realpath.sh

#!/usr/bin/env bash
set -eu
# ----------------------------------------------------------------------------
# Find real file path of current script
# https://stackoverflow.com/questions/59895/getting-the-source-directory-of-a-bash-script-from-within
# ----------------------------------------------------------------------------
source="${BASH_SOURCE[0]}"
while [[ -h "$source" ]]
do # resolve $source until the file is no longer a symlink
  dir="$( cd -P "$( dirname "$source" )" && pwd )"
  source="$(readlink "$source")"
  [[ $source != /* ]] && source="$dir/$source" # if $source was a relative symlink, we need to resolve it relative to the path where the symlink file was located
done
ROOT_DIR="$( cd -P "$( dirname "$source" )" && pwd )"
export ROOT_DIR