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headersyum clean packages #清理/var/cache/yum下的软件包yum clean metadata...1234

Linux释放内存

释放网页缓存(To free pagecache):

sync; echo 1 > /proc/sys/vm/drop_caches1

释放目录项和索引(To free dentries and inodes):

sync; echo 2 > /proc/sys/vm/drop_caches1

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_caches1