How to join PDF pages using pdfunite

PDFUnite is a tool that can be used to join together multiple PDF files into a single output file.

• To install this tool, install the poppler-utils package which it ships under:

$ sudo apt install poppler-utils

• To join multiple input files in-1.pdf, in-2.pdf and so on into a single output file out.pdf:

$ pdfunite in-1.pdf in-2.pdf out.pdf

Tried with: Poppler 0.62.0 and Ubuntu 18.04