Merge and split PDFs
To make one PDF file out of many is not so hard on Linux. Usually there is ghostscript already installed. You can use
gs -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=merged.pdf\
file1.pdf file2.pdf file3.pdf
to do that. instead of providing every single filename something like *.pdf is more usable.
To extract a few pages out of one big PDF you can use:
gs -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=pages_10_to_15.pdf\
-dFirstPage=10 -dLastPage=15 bif_file.pdf