centos: yum清除緩存

清除緩存目錄(/var/cache/yum)下的軟件包 命令：yum clean packages

清除緩存目錄(/var/cache/yum)下的 headers 命令：yum clean headers

清除緩存目錄(/var/cache/yum)下舊的 headers 命令：yum clean oldheaders

清除緩存目錄(/var/cache/yum)下的軟件包及舊的headers 命令：yum clean, yum clean all (= yum clean packages; yum clean oldheaders)

下載緩存yum makecache