linux清理buffer缓存脚本

[root@host-172-21-210-62 opt]# more cleanCache.sh
#!/bin/bash
#每24小时清除一次缓存
echo "开始清除缓存"
sync;sync;sync #写入硬盘，防止数据丢失
sleep 10 #延迟10秒
echo 1 > /proc/sys/vm/drop_caches
echo 2 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches

[root@host-172-21-210-62 ~]# free -g
              total        used        free      shared  buff/cache   available
Mem:             31           4           6           1          19          24
Swap:             0           0           0

[root@host-172-21-210-62 opt]# sh cleanCache.sh

[root@host-172-21-210-62 opt]# free -g
              total        used        free      shared  buff/cache   available
Mem:             31           4          23           1           2          24
Swap:             0           0           0

Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.
To free pagecache:
echo 1 > /proc/sys/vm/drop_caches
To free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches
To free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches
As this is a non-destructive operation, and dirty objects are notfreeable, the user should run “sync” first in order to make sure allcached objects are freed.
This tunable was added in 2.6.16.