Merge PDF with pdftk
pdftk 00-page1.pdf 01-page2.pdf 03-page3.pdf cat output OUT.pdf
Reduce the size of the PDF
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf
(source : http://www.mnt-tech.fr/blog/gnulinux/comment-reduire-la-taille-dun-fichier-pdf-en-ligne-de-commande-sous-linux/ )
