#!/bin/sh

awk '{u=$2+$4; t=$2+$4+$5; if (NR==1){u1=u; t1=t;} else printf("%.0f%%\n", ($2+$4-u1) * 100 / (t-t1)); }' <(grep 'cpu ' /proc/stat) <(sleep 0.01;grep 'cpu ' /proc/stat)