当你先已用ports安装过某一软件，再次安装同一项时，会出现类似：You may wish to “make deinstall” and install this port again
by “make reinstall” to upgrade it properly.
If you really wish to overwrite the old port of PORTS資料夾位置
without deleting it first, set the variable “FORCE_PKG_REGISTER”
in your environment or the “make install” command line.
的错误。
解决办法：只要在make install 时加上 FORCE_PKG_REGISTER=”yes” 就可以强制安裝
