case "$AWK" in
"")	AWK=./gawk ;;
esac
# above is more portable than what follows
#AWK=${AWK:-./gawk}
for i in $*
do
	if test ! -r $i
	then
		echo "chem: can't open file $i" 1>&2
		exit 1
	fi
done
$AWK -f chem.awk $*
