I used to use pdfmod for Linux to concatenate multiple PDF files together or to remove pages from a PDF file. pdfmod has mono libraries (open source MS .NET implementation) as a dependency, however, and they take up over 100 MB on disk when installed.
I have found a nice, lightweight replacement, however. pdfshuffler has just a handful of python dependencies and takes up less than 5 MB on disk. It has all the functionality of pdfmod but is much lighter. It can be found in the default repos on Fedora 24 and in the Arch User Repository. Highly recommended!
Note that you may run into a python bug when running pdfshuffler; you simply need to change ~2 lines of Python source as a workaround: