linux清理yum缓存以及释放内存

清理yum缓存

清理yum缓存使用yum clean 命令，yum clean 的参数有headers, packages, metadata, dbcache, plugins, expire-cache, rpmdb, all

yum clean headers  #清理/var/cache/yum的headers
yum clean packages #清理/var/cache/yum下的软件包
yum clean metadata
...

Linux释放内存

释放网页缓存(To free pagecache):

sync; echo 1 > /proc/sys/vm/drop_caches

释放目录项和索引(To free dentries and inodes):
sync; echo 2 > /proc/sys/vm/drop_caches

释放网页缓存，目录项和索引（To free pagecache, dentries and inodes）:
sync; echo 3 > /proc/sys/vm/drop_caches

效果：

[root@izuf6dtic2d71rbvtn6126z jvm]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1838        1511          80           1         246         153
Swap:             0           0           0
[root@izuf6dtic2d71rbvtn6126z jvm]# sync; echo 3 > /proc/sys/vm/drop_caches 
[root@izuf6dtic2d71rbvtn6126z jvm]# free -m 
              total        used        free      shared  buff/cache   available
Mem:           1838        1511         203           1         122         180
Swap:             0           0           0
[root@izuf6dtic2d71rbvtn6126z jvm]#