If you get a lot of “path not found” messages when you use whereis or which, you might want to makeadditions to the list of directories in the path statement in .cshrc in your home directory.
(如果使用whereis或which时得到大量的"path not fount"信息提示，你可能需要在你的home目录中的.cshrc文件中的路径声明里添加相应目录的列表)。