How to add bookmarks to a PDF document on Linux

In a PDF document, bookmarks can be added as a navigational tool to allow readers to locate and quickly move to particular sections in the document by clicking on bookmark links. If a PDF file is a very log document with hundreds of pages, adding properly organized bookmarks can be essential to guide users to browse the document effectively. PDF bookmarks can be implemented with the pdfmark operator, which is part of a PostScript language extension.