#自动清理缓存脚本
[root@k8s-node3 ~]# vim freemem.sh
#! /bin/sh
#当前已使用内存大小
used=`free -m | awk 'NR==2' | awk '{print $3}'`
#当前剩余的内存大小
free=`free -m | awk 'NR==2' | awk '{print $4}'`
echo "===========================" >> /var/log/mem.log
date >> /var/log/mem.log
echo "Memory usage before | [Use：${used}MB][Free：${free}MB]" >> /var/log/mem.log
#判断真值
if [ $free -le 2048 ] ; then
sync && echo 1 > /proc/sys/vm/drop_caches
sync && echo 2 > /proc/sys/vm/drop_caches
sync && echo 3 > /proc/sys/vm/drop_caches
used_ok=`free -m | awk 'NR==2' | awk '{print $3}'`
free_ok=`free -m | awk 'NR==2' | awk '{print $4}'`
echo "Memory usage after | [Use：${used_ok}MB][Free：${free_ok}MB]" >> /var/log/mem.log
#返回值信息
echo "OK" >> /var/log/mem.log
else
echo "Not required" >> /var/log/mem.log
fi
exit 1
#脚本授予相应权限
[root@k8s-node3 ~]# chmod 755 freemem.sh
-rwxr-xr-x 1 root root 874 12月 3 11:41 freemem.sh
#添加定时任务
[root@k8s-node3 ~]# crontab -e
0 23 * * * root/home/user/freemem.sh 65 >> root/home/user/freemem_log.txt
#查询定时任务
[root@k8s-node3 ~]# crontab -l
#常用命令注解
systemctl status crond.service #启动服务
systemctl stop crond.service #关闭服务
systemctl status crond.service #服务状态
systemctl restart crond.service #重启服务
systemctl reload crond.service #重新载入配置
systemctl enable crond.service #加入开机自启动
systemctl list-unit-files | grep crond #查看是否开启自启动
