Checking PDF Colour base (RGB or CMYK) on Ubuntu

RGB or CMYK
I needed this thing for sending out a PDF file to printers (ad in a magazine). These are some notes for Ubuntu 9.10 (Karmic):

• Install imagemagick package, which contains identify command:
  sudo apt-get install imagemagick
• Run identify command on a PDF file to check if it contains RGB or CMYK colours:
  identify -verbose MyPdfFile.pdf

Additional comments

• Ran into some Gimp plugin package, but was not sure how to use it
• In Scribus, when exporting to PDF, one can select "Printer" in the colour tab. That created CMYK PDF file. Was not sure if it was the best quality though. Some experimenting needed.