Merge PDFs in Ubuntu

snipped by FOBioPatel

using GS (ghostscript)

code merges pdf's: 0.pdf, 1.pdf, and 2.pdf

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combinedpdf.pdf -dBATCH 0.pdf 1.pdf 2.pdf