I want to write a helper function to send the link file (usually ebooks)
under the point to Kindle path like (/run/media/username/Kindle/documents/).
Hope this function can provide the following functionalities:

- check whether the source file (ebook) exist in Kindle?
- check the source file format, if not Kindle supported, then convert it
with command `ebook-convert` which is comes from program "Calibre".

I wander how to get the link actual path under the point?
For example, org link like this:

[[file:Data/Books/kk.epub][kk.epub]]
[[file+sys:/home/username/Documents/kk2.mobi][kk2.mobi]]

[stardiviner]           <Hack this world!>      GPG key ID: 47C32433
IRC(freeenode): stardiviner                     Twitter:  @numbchild
Key fingerprint = 9BAA 92BC CDDD B9EF 3B36  CB99 B8C4 B8E5 47C3 2433
Blog: http://stardiviner.github.io/