EDIT2: Overall I have asked the wrong question. I just let it stay here, and pen down a new forum entry.
EDIT: Changed Shape to Poly. That’s what I’m really looking for. 
Hi! I have found poly data on geofabrik for boundaries of for example Germany or Bavaria. Those datas were in human readable form, so I could easily copy and paste them in my text editor and work on them. (Example of the start of Bavaria “bayern.poly”:
How can I get for example such poly data for all streets in Berlin out of the Germany-file germany-latest.osm.bz2 ?
(I can work with binary data, too, so it’s not neccessary to have the coordinates as text-file.)
Greetings
John