4 ways you can edit a PDF with the pdftk-java command: 
Between technology whitepapers, manuscripts, and RPG books, I deal with lots of PDFs every day. The PDF format is popular because it contains processed PostScript code. PostScript is the native language of modern printers, so publishers often release a digital version of a book as a PDF because they’ve invested in the time and effort to produce a file for print anyway. But a PDF isn’t intended to be an editable format, and while some reverse processing is possible, it’s meant to be the last stop for digital data before it’s sent to the printer.
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