CentOS7上手动释放内存

## freemem.sh

``` 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 1000 ] ; 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

```

定时任务命令

``` sh

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

```