LInux-定时释放

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1、vim编辑脚本

vim /opt/freemem.sh

#!/bin/bash

used=`free -m | awk 'NR==2' | awk '{print $3}'`
free=`free -m | awk 'NR==2' | awk '{print $4}'`

echo "===========================" >> /var/log/mem.log
date >> /var/log/mem.log
echo "Memory usage | [Use：${used}MB][Free：${free}MB]" >> /var/log/mem.log

if [ $free -le 100 ] ; 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" >> /var/log/mem.log
else
                echo "Not required" >> /var/log/mem.log
fi

2、赋予脚本执行权限，并加入计划任务

chmod 755 /opt/freemem.sh
echo "*/30 * * * * root /opt/freemem.sh" >> /etc/crontab