Originally Posted by gt_undergrad
Calibre now will copy all your books from the current library to Library 2. In Calibre, delete the books you don't intend to keep in Library 2. (Don't delete them in the folder --- you need to use Calibre to delete them!)
Calibre will MOVE the books to the new library. If you delete them, they are gone. POFF!
Copy the folder Calibre Library. The copy may be named "Calibre Library (copy)".
Then create a new shortcut for calibre, using this command:
calibre --with-library="Calibre Library (copy)"
Start Calibre using the new shortcut and verify in Preferences that you are using the copy.
Edit: Updated to 0.7.9 and the Preferences setting for the library is gone... Good!