今日更新系统，出现如下错误：
error: could not open file /var/lib/pacman/sync/core.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/core.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/community.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/community.db: Unrecognized archive format
这种错误可能是由于源出现了故障，近日一直使用163的源，速度很快，不想出了这个问题
换一个源就好了
/etc/pacman.d/mirrorlist