- PDFtk (PDFtk is available in the AUR. You can install it using packer or yaourt front-ends.)
pdftk file1.pdf file2.pdf fiel3.pdf cat output outputfile.pdf
or
pdftk *.pdf cat output outputfile.pdf
- Poppler (Poppler is a PDF rendering library based on the xpdf-3.0 code base.)
pdfunite file1.pdf file2.pdf file3.pdf outputfile.pdf