shell中加减乘除运算 cpu 内存的脚本监控

shell中计算除法，基本的方法有几种
t1=3
t2=6
1）expr
num=`expr $(($t1/$t2))`
num的结果为0，因为expr不支持浮点算法
2）bc
echo "scale=2;$t1/$t2"|bc
scale用来控制小数点后面保留的位数
3）awk
awk 'BEGIN{printf "%.2f%\n",('$t1'/'$t2')}'
awk 'BEGIN{printf "%.2f%\n",('$t1'/'$t2')*100}'

乘法

usage_mem_percent=`echo $t1 \* 100|bc`

加法：

total_cpu_percent=`echo "$t1+$t2"|bc`

比较：

flag=`expr $usage_cpu \> "0.95"` 大于 flag=1

例子（监控cpu和内存总占用量大于95%报警发邮件）：

#!/bin/sh
MAILX=/usr/bin/mailx
NOTIFY="194915592@qq.com"
FROM="***@****.com"
DATE=`date +%Y%m%d%H`
DIR="/root/monitor/"
HOSTNAME=`hostname`
NUM="100"
cd $DIR
rm report_cpu_mem.`date -d -1day +%Y%m%d`*
rm report_cpu_mem.$DATE
########################### cpu ##########################
#system used percent of cpu and user used percent of cpu e.g 3.2%usr , 4.5%sys , user_cpu_percent=3.2 ,sys_cpu_percent=4.5
user_cpu_percent=`top -n 1 |grep Cpu|awk '{print $2}'|cut -d "%" -f 1`
sys_cpu_percent=`top -n 1 |grep Cpu |awk '{print $3 }' |cut -d "%" -f 1`
total_cpu_percent=`echo "$user_cpu_percent+$sys_cpu_percent"|bc`
#cpu number e.g 60% used , then usage_cpu=0.6
usage_cpu=`echo "scale=2;$total_cpu_percent/$NUM"|bc`
########################### mem ##########################
#total memory and used memory , e.g total 25620K , used 2222K, then total_mem=25620, used_mem=2222k
total_mem=`top -n 1 |grep Mem |awk '{print $3}'|cut -d "k" -f 1`
used_mem=`top -n 1 |grep Mem |awk '{print $5}'|cut -d "k" -f 1`
#memory number e.g 30% used, then usage_mem=0.3
usage_mem=`echo "scale=2;$used_mem/$total_mem"|bc`
#the percent of memory used , e.g 63.3% , then usage_mem_percent=63.6
usage_mem_percent=`echo "0"$usage_mem \* 100|bc`
flag=`expr "0"$usage_cpu \> "0.95"`
flag1=`expr "0"$usage_mem \> "0.95"`
if [ "$flag" == "1" ];then
echo "The cpu Utilization on $HOSTNAME is over 95%. " >>report_cpu_mem.$DATE
echo "user had used "$total_cpu_percent"% cpu" >>report_cpu_mem.$DATE
echo "system had used "$sys_cpu"% cpu">>report_cpu_mem.$DATE
echo "Please check below processes:" >>report_cpu_mem.$DATE
ps aux|head -1;ps aux|grep -v PID|sort -rn -k +3|head >>report_cpu_mem.$DATE
$MAILX -s "the cpu of $hostname used too much , please check it" $NOTIFY<report_cpu_mem.$DATE
fi
if [ "$flag1" == "1" ] ;then
echo "The mem Utilization on $HOSTNAME is over 95%. " >>report_cpu_mem.$DATE
echo "this host had used $usage_mem_percent"%" memory" >>report_cpu_mem.$DATE
echo "Please check below processes:" >>report_cpu_mem.$DATE
ps aux|head -1;ps aux|grep -v PID|sort -rn -k +4|head >>report_cpu_mem.$DATE
$MAILX -s "the host $HOSTNAME used too much memory or cpu , please check it" $NOTIFY<report_cpu_mem.$DATE
fi

(责任编辑：IT)

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shell中加减乘除运算 cpu 内存的脚本监控