#!/bin/sh
# return the value of the environment variable ALFPROLOG
# or, if undefined, the value "quintus" and a warning message

if [ "XX${ALFPROLOG}" = "XX" ]
then
  echo "WARNING: environment variable ALFPROLOG is undefined!" >&2
  echo "         I assume you want to use the Quintus-Prolog version." >&2
  echo >&2
  echo quintus
else
  echo ${ALFPROLOG}
fi
