I need to resize a pdf (to remove the margins). It's not an image in pdf, it's a book. But, of course, the upper/lower margins are thinner than the left/right ones. So I was wondering whether there was a way, in ubuntu, to resize a pdf but with different resizing factors for horizontal and vertical resize.
Inkscape, available in the repositories, can edit PDF files. Probably depends somewhat on the contents of your PDF as to whether or not you will be happy with the output, but that would be my first option.