How do I resize an image so that the longest size is shorter or equal to an amount?

Question

I think that

mogrify -resize \"1000>\" *.jpg

resizes a bunch of jpegs so that the shorter side is 1000px if that side was longer than 1000px

Answer 1

It should keep the aspect ratio / image proportions when using a geometry string with ">", so you can just do:

mogrify -resize "1000x1000>" *.jpg

So you're explicitly limiting the image to being, at most, 1000x1000 pixels, and keeping the current aspect ratio of the image.