pdfattach
adds a new embedded file to an existing PDF file
TLDR
Add attachment to PDF
$ pdfattach input.pdf file_to_attach output.pdf
Replace existing attachment with same name$ pdfattach -replace input.pdf file_to_attach output.pdf
Display help$ pdfattach --help
Display version$ pdfattach -v
SYNOPSIS
pdfattach [options] PDF-file file-to-attach output-PDF-file
DESCRIPTION
pdfattach adds a new embedded file (attachment) to an existing PDF file. The attachment is stored inside the PDF and can be extracted using pdfdetach.
PARAMETERS
-replace
Replace an existing attachment with the same name if it exists-h, --help
Display usage information-v
Display version information
CAVEATS
The original PDF file is not modified; a new output file is created with the attachment. To update a file in place, output to a temporary file and then rename it.
HISTORY
pdfattach is part of poppler-utils, a set of command-line utilities based on the Poppler PDF rendering library for working with PDF files.

