Just a thin wrapper over the GhostScript command I discovered here.
Copy the script somewhere on your machine, then create an alias in your ~/.profile file by inserting the line, eg
alias pdfmerge='python3 ~/Tools/pdfmerge.py'
File names can be input with or without the .pdf extension. When you are finished entering file names, entering a blank space will prompt for the output name.
In its current form the files input must be in the current working directory.
PDF-insertion tool. Break up a document into before/after sections, then use the merging functionality to put it back together.
Starts to become a pdf-utility suite.