Local file
Files can also be linked using the url or the href commands. You simply
have to add the string run: at the beginning of the link string:
\url{run:/path/to/my/file.ext}
\href{run:/path/to/my/file.ext}{text displayed}
You can use relative paths to link documents near the location of your
current document; in order to do so, use the standard Unix-like notation
(./ is the current directory, ../ is the previous directory, etc.)
就是说要链接到外部文件的话要加上run:
后面跟的是文件的地址，是MAC的话就用UNIX的./代表当前目录