My OS is Ubuntu. I tried using pdfunite foo.pdf bar.pdf foobar.pdf, but was prompted with the exception:
Unimplemented Feature: Could not merge encrypted files ('bar.pdf')
The stats of the encrypted file:
- Author: US Government IRS
- Producer: Text® 5.4.2 ©2000-2012 1T3XT BVBA (AGPL-version)
- Creator: eServices TDS
- Format: PDF-1.4