Use xargs -0 instead of --null

run-alive.sh

@@ -1,6 +1,6 @@
 for i in "inputs/alive/instcombine" "inputs/alive/unit"; do
 	echo "Running ${i}/*.opt .."
-	find ${i} -name "opt*" -print0 | sort -z | xargs --null cat > ${i}/all.opt
+	find ${i} -name "opt*" -print0 | sort -z | xargs -0 cat > ${i}/all.opt
 	lean -q --run src/main.lean -verifyopt ${i}/all.opt > output.txt
 	python3 check_diff.py output.txt ${i}/answ.txt
 	rm ${i}/all.opt