[gbm]

Originally Posted by KoopaOne

My knowledge of Linux is good, Windows is pretty good. I can program in Python, so no newb here.
I did not do a backup from inside Calibre, since it's the Portable Version - i simply copied the complete directory structures to a external HD.

Do you still have access to the windows computer?

From the calibre manual:

Note

This import/export functionality is only available from calibre version 2.47 onwards. If you have an older version of calibre, or if you encounter problems with the import/export, you can just copy over your calibre library folder manually, as described in the next paragraph.

Spoiler:

Simply copy the calibre library folder from the old to the new computer. You can find out what the library folder is by clicking the calibre icon in the toolbar. Choose the Switch/create calibre library action and you will see the path to the current calibre library.

Now on the new computer, start calibre for the first time. It will run the Welcome wizard asking you for the location of the calibre library. Point it to the previously copied folder. If the computer you are transferring to already has a calibre installation, then the Welcome wizard wont run. In that case, right-click the calibre icon in the toolbar and point it to the newly copied directory. You will now have two calibre libraries on your computer and you can switch between them by clicking the calibre icon on the toolbar. Transferring your library in this manner preserver all your metadata, tags, custom columns, etc.

bernie