#!/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

然后

chmod 755 /opt/freemem.sh

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

完事

https://blog.csdn.net/yan7895566/article/details/82834200