I have several pdfs, of which my pdf-viewer can show the outline, like in this example:
While this is a great feature, there are unfortunately some pdfs, that have no such feature implemented!
Only bookmarks can be added, but for me that is not an option, because it‘s a viewer-dependent solution. For some books, it would be very helpful to have such an outline, so i thought about adding that myself, but i couldn‘t find any program, script or different solution except for Adobe Acrobat Pro, which is much too expensive for me.
Does anyone know something that suits my problem? A Linux solution would be prefered.

