Problem
I have unprotected
input1.pdfinput2.pdf
and I want to create one single encrypted.pdf.
My try
I looked up QPDF’s manual and tried the following command.
qpdf --empty --pages input{1,2}.pdf --encrypt upw opw 256 -- encrypted.pdf
but I got this error.
qpdf: unrecognized argument --encrypt (pages options must be terminated with --)
For help:
qpdf --help=usage usage information
qpdf --help=topic help on a topic
qpdf --help=--option help on an option
qpdf --help general help and a topic list
Solution
The sentence inside the parentheses says it all.
qpdf --empty --pages input{1,2}.pdf -- --encrypt upw opw 256 -- encrypted.pdf