检测系统负载

#!/bin/bash
cputotal=`head -1 /proc/stat |awk '{print $2+$3+$4+$5}'`
cpunow=`head -1 /proc/stat |awk '{print $2+$3+$4}'`
memtotal=`free  -m |sed -n '/Mem/p'|awk '{print $2}'`
memnow=`free  -m |sed -n '/Mem/p'|awk '{print $3}'`
cpuused=`gawk -v x=$cpunow -v y=$cputotal 'BEGIN{printf "%.5f",x * 100/y}'`
memused=`gawk -v x=$memnow -v y=$memtotal 'BEGIN{printf "%.5f",x * 100/y}'`
case "$1" in
  cpu)
        echo $cpuused
        ;;
  mem)
        echo $memused
        ;;
  clu)
        size=`(stat $2 | grep Size |awk '{print $2}')`
        num=`(stat $2 | grep Size |awk '{print $4}')`
        block=`expr $size / $num`
        echo $block
        ;;
  *)
        echo "it used cpu;mem;clu"
        ;;
esac