定时 回收 CentOS 系统 内存

#!/bin/bash

LIMIT=512
LOG_FILE="/data/logs/timing_dropcaches.log"

#定时清理系统内存
#https://blog.csdn.net/gaojinshan/article/details/40710369
used=`free -m | awk ‘NR==2‘ | awk ‘{print $3}‘`
free=`free -m | awk ‘NR==2‘ | awk ‘{print $4}‘`

echo "===========================" >> $LOG_FILE
date +"%Y-%m-%d %H:%M.%S" >> $LOG_FILE
echo "Memory usage | [Use：${used}MB][Free：${free}MB] | limit[${LIMIT}MB]" >> $LOG_FILE

# drop caches when the free memory less than 512M
if [ $free -le $LIMIT ] ; 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
 echo "OK" >> $LOG_FILE
else
 echo "Not required" >> $LOG_FILE
fi

#每半小时检查内存使用情况，并清理一次内存
*/30 * * * *  /data/shell/timing_dropcaches.sh >> /data/logs/timing_dropcaches.log

#删除3天前的日志
0 1 * * * /usr/bin/find /data/logs/ -name *.log -mtime +3 | grep 2018 | xargs rm -Rf {} > /dev/null 2>&1