Answering: how can I reference the scripts directory and the working directory in GNU bash?

directories.bash

#!/bin/bash

# `dirname` is part of GNU coreutils, but is okay to use since it's in the Unix standard.
DIRNAME=`dirname $0`
echo script is at $DIRNAME

# Alternative, use pure bash substitution.
DIRNAME=${0%/*}
echo script is at $DIRNAME

# bash sets the current working directory in PWD
echo you are at $PWD