Handling multiple pdf’s can be a pain, and combining multiple pdf’s is not as easy as merging doc files. So how to achieve this?

The simplest and the fastest way is using pdftk. Install Ubuntu if you are not a regular user, install this on a VirtualBox image and install pdftk on your instance by typing

sudo apt-get install pdftk

Once the installation is complete, you can now start merging pdf files on the fly by using the following command

pdftk *.pdf cat output merged.pdf

or

pdftk 1.pdf 2.pdf 3.pdf cat output merged.pdf

There are mutiple options to this which you can find out using man or using google