convert a PDF file to images

With linux command convert, I can convert a PDF file to other image format. For example:

• convert foo.pdf to foo.png (or foo1.png, foo2.png.. etc if there are multiple pages in foo.pdf):

  $ convert -resize 1024x1024 -density 144 foo.pdf foo.png
  

• One can specify file format by the file extension.

  $ convert foo.pdf foo.jpg
  

• one can specify the output size

  $ convert -resize 1024x1024 foo.pdf foo.png