Set it to fail out if AMBERHOME doesn't exist.
# This file defines where WEST and Amber can be found
# Modify to taste
-# Inform WEST where to find Amber
+# Inform WEST where to find Amber.
+# If AMBERHOME isn't set, it's unlikely that the libraries can be found, regardless of whether cpptraj/pmemd exist in the path.
+if [[ -z "$AMBERHOME" ]]; then
+ echo "AMBERHOME environ variable not set. Source amber.sh, or modify env.sh such that WESTPA knows where AMBER is."
+ exit
+fi
export PATH=$AMBERHOME/bin:$PATH
# Set environment variables for Amber for convenience
