pdf-merge merges PDF files, while preserving their bookmarks and metadata such as title and author. If the original files have no bookmarks, it attempts to guess them by using the filenames as chapter names. It has been tested with ebooks from Cambridge university press, CRC and Springer.

This is a modified version of the program written by Trevor King at
http://blog.tremily.us/posts/PDF_bookmarks_with_Ghostscript/pdf-merge.py
This has enhanced unicode support, various fixes and enhancements.