Combine multiple PDFs into one file

we will see one example how to combine pdf files let us assume we have 001.pdf, 002.pdf files and now we need to combine this files using the following command

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combinedpdf.pdf -dBATCH 001.pdf 002.pdf

gswin32c.exe -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combinedpdf.pdf -dBATCH 001.pdf 002.pdf

In the above command after “-sOUTPUTFILE=” type whatever name you want for the merged file (don’t forget to append .pdf to the end of the file name).

After you run the above command, a new PDF file called combinedpdf.pdf will be created with your individual files merged according to the order you list.

Reference:
http://www.debianadmin.com/combine-multiple-pdfs-into-one-file-in-ubuntu-linux.html
http://www.rizauddin.com/2009/04/how-to-merge-or-combine-pdf-files-with-ghostscript