在lua中创建一个临时文件

这是我的函数的样子：

do
   function upload_file(web)

      f =  -- creates a temporary file
      f:write(file.contents)     -- writes the content of the file uploaded in the temp file
      f:seek("set",0)          -- we go back at the beginning
      s = f:read("*a")          -- read it out
      print (s)                 -- print it out
      f:close()                 -- close it
   end
end