convert multiple_pages.pdf +adjoin broken_up_%d.jpg
Prefix that with
gm if you’re running GraphicsMagick rather than ImageMagick.
%d part means that a number should be placed there to indicate the page number from the original that the image file contains. So a three-page PDF will produce
You can get a better default sort order on the files by telling *magick to zero-prefix the number with a slight change to the format string. So changing
%03d will starting numbering at
You should be able to generate any image file type that *magick supports by just specifying the destination extension (jpg, png, gif, etc.).