使用shell脚本监控Linux主机

[[email?protected] ~]# cat sysmon.sh 
#!/bin/bash
dug=$(df -h | grep "/$" | awk ‘{print $5}‘ | awk -F% ‘{print $1}‘)
cug=$(expr 100 - $(mpstat | tail -1 | awk ‘{print $12}‘ | awk -F. ‘{print $1}‘))
mug=$(expr $(free | grep "Mem:" | awk ‘{print $3}‘) * 100 / $(free | grep "Mem:" | awk ‘{print $2}‘))
alog="/tmp/alert.txt"
email="root"                   #邮件发送目的地址变量
if [ $dug -gt 90 ]
then
        echo " 磁盘占用率：$dug % " >> $alog
fi
if [ $cug -gt 80 ]
then
         echo " cpu使用率: $cug % " >> $alog
fi
if [ $mug -gt 90 ]
then
        echo " 内存使用率：$mug % " >> $alog
fi
if [ -f $alog ]
then
 cat $alog | mail -s "Host Alert" $email      #有关发送邮件的配置
        rm -rf $alog
rm -rf $alog
fi

[[email?protected] ~]# systemctl status crond            #查询crond服务是否为启动状态
● crond.service - Command Scheduler
   Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
   Active: active (running) since 四 2019-05-23 05:03:09 CST; 1h 24min ago
 Main PID: 1339 (crond)
    Tasks: 1
   CGroup: /system.slice/crond.service
           └─1339 /usr/sbin/crond -n
         ...................

[[email?protected] ~]# crontab -e                    #创建新的任务计划
*/30          *      *      *           *       /root/sysmon.sh          
[[email?protected] ~]# crontab -l              #查看任务计划
*/30          *      *      *           *       /root/sysmon.sh