ImageMagick – How to Append Images Vertically

Use the ImageMagick "montage" command, specifically the "-tile" option. See http://www.imagemagick.org/Usage/montage/ for details.

ImageMagick accepts format specifiers in its command line:

convert -density 600 foo.pdf foo-%02d.jpg

Quote from the doc:

Filename References

Optionally, use an embedded formatting character to write a sequential image list. Suppose our output filename is image-%d.jpg and our image list includes 3 images. You can expect these images files to be written:

image-0.jpg
image-1.jpg
image-2.jpg