PDF operations
1 pdftk
1.1 Extract pages from a pdf file
pdftk input.pdf cat start-end output output_start-end.pdf
e.g.: Extract the second page of main.pdf
pdftk main.pdf cat 2 output main-2.pdf
1.2 Merge several pdf files
pdftk 1.pdf 2.pdf 3.pdf cat output main.pdf