How do I know why I have a port?

[Jack Repenning]

Sometimes, I notice I have some port installed that I have no conscious interest in. I'm sure it's there because it's depended upon by some other port that I do care about (or recursively), but is there some way I can find out what that would be?

I see that "port info whatever" tells me what stuff "whatever" depends upon, but I want the inverse of that.

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Jack Repenning