è presente anche una bella gemma...tanto per rimanere in tema ruby


nome: pdf-toolkit
Version:0.49
homepage:http://rubyforge.org/projects/pdf-toolkit/

Description:
A Ruby interface to PDF metadata. Allows manipulation of a document's Author, Title, Keywords, and other attributes from a PDF's Info dictionary. Implemented as a wrapper around pdftk, which is available for several platforms.

ciao ciao