I found this one on SHELL FU – I haven’t tried it out yet but SHELL FU don’t post commands that don’t work. One comment I saw on Twitter was: Good + Evil = New. Anyway, here it is.

To combine multiple pdfs into one, for printing purposes or distribution:

$ gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combine.pdf -dBATCH 1.pdf 2.pdf 3.pdf