What do you call confused ? ~ is a shortcut for the Home-Directory of a user on Linux/Unix systems. So that's always at home.
To update my calibre under UBuntu, I just go by the defaults it provides me - nothing more. Just issue:
Code:
sudo python -c "import urllib2; exec urllib2.urlopen('http://calibre.kovidgoyal.net/download_linux_binary_installer').read(); main()"
on the command line - answer to the questions - and voila.
It just updates the code, not your eBook DB.