Here is Inkscape doing it:
My last choice (just for pdf, not for other jobs) would be Gimp for pdf editing, but you can do it.
If you need to do something repetitive, obviously you should script it using command line tools (there are many, just type 'apropos pdf' to find them on your system).
I've scripted e.g. watermarking a bunch of pdf, adding a logo...
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko