concatenate pdfs with ghostscript

brew install gs to get it if you don't have it already, then:

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=combined.pdf one.pdf two.pdf three.pdf [...]

• -q: quiet, don't write to stdout
• -dNOPAUSE: Disables the prompt and pause at the end of each page
  • not sure why anybody would want a prompt at the end of each page, but I also don't understand ghostscript broadly
• BATCH: the manual doesn't mention it
• for -sDEVICE, the manual says You can also check the set of available devices from within Ghostscript: invoke Ghostscript and type 'devicenames =='
  • but it doesn't mention pdfwrite particularly
  • the devicenames list is extremely cryptic

I got the command from stack overflow