Ignacio Serantes wrote:Can you told me how can I search for and actor in my movies or for a compositor in audio files using grep?.

In my opinion does such information primarily belong into the file itself, as it is the case with id3/vorbis tags. For some reason this never took off for movies, and while the possibility exist in the mkv and mp4 container formats, I am not aware of a single movie player/manager software that is able to read or write such tags.

Nepomuk should only be used to extract those informations from these kind of files (which it can't do (yet?), by the way) and additionally store user related informations, like ratings, views etc. Furthermore, nepomuk could then "know" that a file is a movie and what a movie is. It could "know" that a movie has actors, directors and and who those are. And if connected to a database of actors, it could, when asked to, look up in which movies these actors played as well...