Thank you very much. The good thing:
It automatically overwrites the existing pdf and this cool workflow is possible:
One can generate the pdf and see it a few seconds later in a new tab, side by side to the markdown file. 
The bad thing: I have to change the wiki links to markdown links, to get the images. And even if I do that, they are not always shown in the output because the image name is unique and obsidian dowes not add the path.
Unicode-Problems:
(I try shell commands later.)