and of course, like all the other calibre utilities, it will be the same on either platform, except Windows ends with .exe, linux doesn't. Assuming you have version 1.15+ installed.
Tweak Book is the old version that just turns the book into an editable folder; this was hidden when Edit was released (still available under Preferences ==> toolbar, as Unpack Book) and switched for Edit book, so you are almost definitely in need of upgrading.
It can be run by right-clicking a book in your library (or hotkey=T) or by running:
Code:
ebook-edit /path/to/book
I believe a .desktop menu item is created too.
Dang, I'm so used to dealing with Windows people, I use Windows references even when answering a linux question!