require

#!/bin/bash

if [ "${REQUIRE_ERR}" = "" ]
then
   export REQUIRE_ERR=0
fi

while [ ${#} -gt 0 ]
do
   which ${1} > /dev/null

   if [ ${?} != 0 ]
   then
      echo "This application requires ${1}.  Install it using your package manager and try again."
      export REQUIRE_ERR=1
   fi

   shift
done