title: How can I detect using Python the insertion of only USBs and hard drives on Ubuntu/Linux?
body: <p>I'm building a backup program which involves detecting when media available for backup is inserted. I've looked into detecting the insertion of backup media, and I'm going to use the file system watch service inotify on the <code>/media/username</code> directory. </p>
  
  <p>The problem is that I've looked into this directory and there are folders that don't represent any currently available medium. How can I detect the list of currently available mediums (USBs, HDDs) and watch for any future ones? More technically, what are the characteristics of an actively available USB/HDD folder in the <code>/media/username</code> directory?</p>