When I wanted to try setting the author and title which should be supported by any format I got:
Code:
>ebook-meta Perry\ Rhodan\ Nr.\ 2300\ -\ Pabel\ Moewig\ Verlag.epub --authors="Robert Feldhoff" --title="Vorboten des Chaos"
Original-Metadaten::
Title : Perry Rhodan Nr. 2300
Author(s) : Pabel Moewig Verlag
Ge?nderte Metadaten::
Title : Perry Rhodan Nr. 2300
Author(s) : Pabel Moewig Verlag
And with some more experimenting I found the bug. ebook-meta is honouring the "Set metadata from filename only" GUI flag. I had this flag set because I wanted to discard buggy meta data on initial import and then fix them with ebook-meta and calibredb.
Now in my understanding the command-line tool should not honour a GUI flag. If this can not be fixed easily then at least a warning should be displayed to inform the user that meta data is read from file-name only.
Martin